BINDER COMPOSITION FOR NON-AQUEOUS SECONDARY BATTERY HEAT-RESISTANT LAYER, SLURRY COMPOSITION FOR NON-AQUEOUS SECONDARY BATTERY HEAT-RESISTANT LAYER, HEAT-RESISTANT LAYER FOR NON-AQUEOUS SECONDARY BATTERY, AND NON-AQUEOUS SECONDARY BATTERY
20220320516 · 2022-10-06
Assignee
Inventors
Cpc classification
C08F220/1804
CHEMISTRY; METALLURGY
C08L33/26
CHEMISTRY; METALLURGY
C08F220/40
CHEMISTRY; METALLURGY
C08F216/1416
CHEMISTRY; METALLURGY
C08F220/58
CHEMISTRY; METALLURGY
C08F220/06
CHEMISTRY; METALLURGY
H01M10/0525
ELECTRICITY
C08F220/58
CHEMISTRY; METALLURGY
C08F220/40
CHEMISTRY; METALLURGY
C08F220/06
CHEMISTRY; METALLURGY
C08F216/1416
CHEMISTRY; METALLURGY
International classification
H01M4/62
ELECTRICITY
Abstract
Provided is a binder composition for a non-aqueous secondary battery heat-resistant layer with which it is possible to produce a slurry composition for a non-aqueous secondary battery heat-resistant layer that has excellent dispersion stability and coatability and that can form a heat-resistant layer for a non-aqueous secondary battery having excellent heat shrinkage resistance. The binder composition for a non-aqueous secondary battery heat-resistant layer contains a water-soluble polymer and water. The water-soluble polymer includes an amide group-containing monomer unit, an acid group-containing monomer unit, and a hydroxyl group-containing monomer unit. The proportional content of the amide group-containing monomer unit in the water-soluble polymer is not less than 63 mass % and not more than 98 mass % and the proportional content of the acid group-containing monomer unit in the water-soluble polymer is not less than 1 mass % and not more than 20 mass %.
Claims
1. A binder composition for a non-aqueous secondary battery heat-resistant layer comprising a water-soluble polymer and water, wherein the water-soluble polymer includes an amide group-containing monomer unit, an acid group-containing monomer unit, and a hydroxyl group-containing monomer unit, and proportional content of the amide group-containing monomer unit in the water-soluble polymer is not less than 63 mass % and not more than 98 mass % and proportional content of the acid group-containing monomer unit in the water-soluble polymer is not less than 1 mass % and not more than 20 mass %.
2. The binder composition for a non-aqueous secondary battery heat-resistant layer according to claim 1, wherein proportional content of the hydroxyl group-containing monomer unit in the water-soluble polymer is not less than 1 mass % and not more than 25 mass %.
3. The binder composition for a non-aqueous secondary battery heat-resistant layer according to claim 1, wherein the hydroxyl group-containing monomer unit is a hydroxyl group-containing (meth)acrylamide monomer unit.
4. The binder composition for a non-aqueous secondary battery heat-resistant layer according to claim 1, wherein a molar ratio of proportional content of the hydroxyl group-containing monomer unit relative to proportional content of the acid group-containing monomer unit in the water-soluble polymer is 0.70 or more.
5. The binder composition for a non-aqueous secondary battery heat-resistant layer according to claim 1, wherein the water-soluble polymer has a weight-average molecular weight of not less than 200,000 and not more than 2,000,000.
6. The binder composition for a non-aqueous secondary battery heat-resistant layer according to claim 1, further comprising a particulate polymer.
7. A slurry composition for a non-aqueous secondary battery heat-resistant layer comprising: non-conductive inorganic particles; and the binder composition for a non-aqueous secondary battery heat-resistant layer according to claim 1.
8. A heat-resistant layer for a non-aqueous secondary battery formed using the slurry composition for a non-aqueous secondary battery heat-resistant layer according to claim 7.
9. A non-aqueous secondary battery comprising the heat-resistant layer for a non-aqueous secondary battery according to claim 8.
Description
EXAMPLES
[0175] The following provides a more specific description of the present disclosure based on examples. However, the present disclosure is not limited to the following examples. In the following description, “%” and “parts” used in expressing quantities are by mass, unless otherwise specified.
[0176] Moreover, in the case of a polymer that is produced through polymerization of a plurality of types of monomers, the proportion in the polymer constituted by a monomer unit that is formed through polymerization of a given monomer is normally, unless otherwise specified, the same as the ratio (charging ratio) of the given monomer among all monomers used in polymerization of the polymer. In the examples and comparative examples, the following methods were used to evaluate the weight-average molecular weight of a water-soluble polymer, the glass-transition temperature and volume-average particle diameter of a particulate polymer, the dispersion stability and coatability of a slurry composition for a heat-resistant layer, the heat shrinkage resistance of a heat-resistant layer, the close adherence of a heat-resistant layer and a substrate, and the cycle characteristics of a secondary battery.
<Weight-Average Molecular Weight of Water-Soluble Polymer>
[0177] An aqueous solution containing a water-soluble polymer that was produced in each example or comparative example was diluted so as to adjust the concentration thereof to 0.5%. Next, caustic soda was added until the pH reached 10 to 12, 1 hour of immersion was performed in a hot water bath of 80° C. or higher, and then dilution to 0.025% was performed with the eluent indicated below so as to produce a sample. The sample was analyzed by gel permeation chromatography under the following conditions in order to determine the weight-average molecular weight of the water-soluble polymer.
[0178] Apparatus: Gel permeation chromatograph GPC (device No. GPC-26)
[0179] Detector: Differential refractive index detector RI (produced by Showa Denko K.K.; product name: RI-201; sensitivity: 32)
[0180] Column: TSKgel GMPWXL×2 (Ø7.8 mm×30 cm; produced by Tosoh Corporation)
[0181] Eluent: 0.1 M Tris buffer solution (pH 9; 0.1 M potassium chloride added)
[0182] Flow rate: 0.7 mL/min
[0183] Column temperature: 40° C.
[0184] Injection volume: 0.2 mL
[0185] Reference sample: Monodisperse polyethylene oxide (PEO) and polyethylene glycol (PEG) produced by Tosoh Corporation and Sigma-Aldrich
<Glass-Transition Temperature of Particulate Polymer>
[0186] A powdered sample obtained by drying a water dispersion containing a particulate polymer at a temperature of 25° C. for 48 hours was used as a measurement sample. After weighing 10 mg of the measurement sample into an aluminum pan, measurement was implemented under conditions prescribed in JIS Z8703 using a differential scanning calorimeter (produced by SII NanoTechnology Inc.; product name: EXSTAR DSC6220) and with a measurement temperature range of −100° C. to 200° C. and a heating rate of 20° C./min to obtain a differential scanning calorimetry (DSC) curve. Note that an empty aluminum pan was used as a reference. The temperature at which a derivative signal (DDSC) exhibited a peak in the heating process was taken to be the glass-transition temperature (° C.). Note that since multiple peaks were measured, the temperature at which a peak having large displacement was exhibited was taken to be the glass-transition temperature of the particulate polymer.
<Volume-Average Particle Diameter of Particulate Polymer>
[0187] The volume-average particle diameter of a particulate polymer was measured by laser diffraction. Specifically, a produced water dispersion containing the particulate polymer (adjusted to a solid content concentration of 0.1 mass %) was used as a sample. In a particle diameter distribution (by volume) measured using a laser diffraction particle size analyzer (produced by
[0188] Beckman Coulter Inc.; product name: LS-13 320), the particle diameter D50 at which cumulative volume calculated from a small diameter end of the distribution reached 50% was taken to be the volume-average particle diameter.
<Dispersion Stability of Slurry Composition for Heat-Resistant Layer>
[0189] After loading 1 kg of a slurry composition for a heat-resistant layer produced in each example or comparative example into a 1 L plastic bottle, the plastic bottle was left at rest for 10 days. A Mix Rotor was then used to perform stirring of the entire plastic bottle that had been left at rest. After this stirring, the slurry composition for a heat-resistant layer inside the plastic bottle was sampled at within 1 cm of the top, and the solid content concentration of the sampled supernatant was measured. The slurry composition in the plastic bottle after stirring was withdrawn from the bottle, and occurrence of adhesion to the bottom of the plastic bottle was checked and was evaluated as follows.
[0190] A: Solid content concentration of supernatant after stirring of 39.5% or more and no adhesion to bottom of plastic bottle
[0191] B: Solid content concentration of supernatant after stirring of 39.5% or more but adhesion to bottom of plastic bottle observed
[0192] C: Solid content concentration of supernatant after stirring of less than 39.5%
<Coatability of Slurry Composition for Heat-Resistant Layer>
[0193] The external appearance of a heat-resistant layer formed from a slurry composition for a heat-resistant layer produced in each example or comparative example was visually observed and was evaluated as follows.
[0194] A: Range over which aggregates, streaks, and/or cissing are not observed is 30 cm×30 cm or more
[0195] B: Range over which aggregates, streaks, and/or cissing are not observed is not less than 10 cm×10 cm and less than 30 cm×30 cm
[0196] C: Range over which aggregates, streaks, and/or cissing are not observed is less than 10 cm×10 cm
<Heat Shrinkage Resistance of Heat-Resistant Layer>
[0197] A heat-resistant layer-equipped separator produced in each example or comparative example was cut out as a square of 12 cm in width by 12 cm in length, and a square having a side length of 10 cm was drawn in an inner part of the cut out square to obtain a test specimen. The test specimen was placed inside a 150° C. thermostatic tank and was left for 1 hour. Thereafter, the area change of the square drawn in the inner part (={(area of square before being left−area of square after being left)/area of square before being left}×100%) was determined as the heat shrinkage rate and was evaluated by the following standard. A smaller heat shrinkage rate indicates that a heat-resistant layer has better heat shrinkage resistance.
[0198] A: Heat shrinkage rate of less than 10%
[0199] B: Heat shrinkage rate of not less than 10% and less than 20%
[0200] C: Heat shrinkage rate of 20% or more
<Close Adherence of Heat-Resistant Layer and Substrate>
[0201] A heat-resistant layer-equipped separator produced in each example or comparative example was cut out as 10 mm in width by 50 mm in length to obtain a test specimen. Next, an SUS plate having double-sided tape (No. 5608 produced by Nitto Denko Corporation) affixed thereto was prepared, and the surface of the heat-resistant layer of the test specimen was affixed to the double-sided tape. One end of the separator substrate was pulled and peeled off at a speed of 50 mm/min such that the peeling face was at 180°, and the strength when the separator substrate was peeled off was measured. A higher peel strength indicates better close adherence of a heat-resistant layer and a substrate.
[0202] A: Peel strength of 60 N/m or more
[0203] B: Peel strength of not less than 30 N/m and less than 60 N/m
[0204] C: Peel strength of less than 30 N/m
<Cycle Characteristics of Secondary Battery>
[0205] A lithium ion secondary battery produced in each example or comparative example was left at rest in a 25° C. environment for 24 hours. Thereafter, the lithium ion secondary battery was subjected to a charge/discharge operation of charging to 4.2 V (cut-off condition: 0.02C) by a constant current-constant voltage (CC-CV) method at a charge rate of 1C and then discharging to 3.0 V by a constant current (CC) method at a discharge rate of 1C, and the initial capacity C0 was measured.
[0206] The lithium ion secondary battery was repeatedly subjected to the same charge/discharge operation in a 25° C. environment, and the capacity Cl after 300 cycles was measured. The capacity maintenance rate AC (=(C1/C0)×100(%)) was calculated and was evaluated by the following standard. A higher capacity maintenance rate indicates a smaller decrease of discharge capacity, and thus indicates better cycle characteristics.
[0207] A: Capacity maintenance rate AC of 85% or more
[0208] B: Capacity maintenance rate AC of not less than 75% and less than 85%
[0209] C: Capacity maintenance rate AC of less than 75%
Example 1
<Production of Aqueous Solution Containing Water-Soluble Polymer>
[0210] A 10 L septum-equipped flask was charged with 6,335 g of deionized water and 190 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator. These materials were heated to a temperature of 40° C., and the inside of the flask was purged with nitrogen gas at a flow rate of 100 mL/min. Next, 939.8 g (74.0%) of acrylamide as an amide group-containing monomer, 127.0 g (10.0%) of acrylic acid as an acid group-containing monomer, and 203.2 g (16.0%) of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer were mixed and were then injected into the flask by a syringe. Thereafter, 200 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator was added into the flask by a syringe, and the reaction temperature was set to 60° C. Once 2 hours had passed, 100 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 95 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added in order to further raise the reaction conversion rate. Once a further 2 hours had passed, 100 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 95 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added. Two hours later, 34 g of a 5% aqueous solution of sodium nitrite as a reaction inhibitor was added into the flask and was stirred. Thereafter, the flask was cooled to 40° C. and was converted to an air atmosphere. The pH of the system was adjusted to 8.0 using 8% lithium hydroxide aqueous solution to thereby yield an aqueous solution containing a water-soluble polymer. The weight-average molecular weight of the obtained water-soluble polymer was measured. The result is shown in Table 1.
<Production of Water Dispersion Containing Particulate Polymer>
[0211] A reactor including a stirrer was supplied with 70 parts of deionized water, 0.15 parts of sodium lauryl sulfate (produced by Kao Corporation; product name: EMAL® 2F (EMAL is a registered trademark in Japan, other countries, or both)) as an emulsifier, and 0.5 parts of ammonium persulfate, the gas phase was purged with nitrogen gas, and the temperature was raised to 60° C.
[0212] Meanwhile, a monomer composition was obtained in a separate vessel by mixing 50 parts of deionized water, 0.5 parts of sodium dodecylbenzenesulfonate, 94.2 parts of n-butyl acrylate as a (meth)acrylic acid ester monomer, 2 parts of methacrylic acid as a hydrophilic group-containing monomer, 0.3 parts of allyl methacrylate and 1.5 parts of allyl glycidyl ether as cross-linkable monomers, and 2 parts of acrylonitrile as another monomer. The monomer composition was continuously added into the reactor over 4 hours to carry out polymerization. The reaction was carried out at 60° C. during the addition. Once the addition was complete, a further 3 hours of stirring was performed at 70° C. to complete the reaction and thereby yield a water dispersion containing a particulate polymer.
[0213] The glass-transition temperature and the volume-average particle diameter of the obtained particulate polymer were measured. The results are shown in Table 1.
<Production of Slurry Composition for Non-Aqueous Secondary Battery Heat-Resistant Layer>
[0214] Alumina particles (produced by Nippon Light Metal Co., Ltd.; product name: LS-256; volume-average particle diameter: 0.5 μm) were prepared as non-conductive inorganic particles, and sodium polyacrylate (produced by Toagosei Co., Ltd.; product name: ARON T-50) was prepared as a dispersant.
[0215] A dispersion liquid was obtained by mixing 100 parts of the non-conductive inorganic particles, 0.5 parts of the dispersant, and deionized water, and then treating the mixture for 1 hour using a bead mill (produced by Ashizawa Finetech Ltd.; product name: LMZ015). In addition, 2 parts of solid content of the aqueous solution containing the water-soluble polymer obtained as described above, 4 parts of solid content of the water dispersion containing the particulate polymer obtained as described above, and 0.3 parts of an ethylene oxide/propylene oxide surfactant (produced by San Nopco Limited; product name: NOPTECHS ED-052) as a wetting agent were mixed so as to produce a slurry composition for a heat-resistant layer having a solid content concentration of 40%. Note that this slurry composition for a heat-resistant layer contained a binder composition for a heat-resistant layer. In other words, production of a slurry composition for a heat-resistant layer and production of a binder composition for a heat-resistant layer were performed at the same time in this example.
[0216] The dispersion stability and coatability of the slurry composition for a heat-resistant layer obtained in this manner were evaluated. The results are shown in Table 1.
<Production of Separator>
[0217] A separator substrate made of polyethylene (produced by Asahi Kasei Corporation; product name: ND412; thickness: 12 μm) was prepared. The slurry composition for a heat-resistant layer produced as described above was applied onto the surface of the prepared separator substrate and was dried at a temperature of 50° C. for 3 minutes to obtain a separator including a heat-resistant layer at one side (heat-resistant layer thickness: 2.5 μm).
[0218] The heat shrinkage resistance of the heat-resistant layer obtained in this manner and also the close adherence of the heat-resistant layer and the separator substrate were evaluated. The results are shown in Table 1.
<Formation of Negative Electrode>
[0219] A 5 MPa pressure-resistant vessel equipped with a stirrer was charged with 33 parts of 1,3-butadiene as an aliphatic conjugated diene monomer, 3.5 parts of itaconic acid as a carboxy group-containing monomer, 63.5 parts of styrene as an aromatic vinyl monomer, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of deionized water, and 0.5 parts of potassium persulfate as a polymerization initiator. These materials were sufficiently stirred and were then heated to 50° C. to initiate polymerization. The polymerization reaction was quenched by cooling at the point at which the polymerization conversion rate reached 96% to yield a mixture containing a particulate binder (styrene-butadiene copolymer). The mixture was adjusted to pH 8 through addition of 5% sodium hydroxide aqueous solution and was then subjected to thermal-vacuum distillation to remove unreacted monomer. Thereafter, the mixture was cooled to 30° C. or lower to yield a water dispersion containing a binder for a negative electrode. A planetary mixer was charged with 48.75 parts of artificial graphite (theoretical capacity: 360 mAh/g) and 48.75 parts of natural graphite (theoretical capacity: 360 mAh/g) as negative electrode active materials and 1 part (in terms of solid content) of carboxymethyl cellulose as a thickener. These materials were diluted to a solid content concentration of 60% with deionized water and were subsequently kneaded at a rotation speed of 45 rpm for 60 minutes. Thereafter, 1.5 parts in terms of solid content of the water dispersion containing the binder for a negative electrode obtained as described above was added and was kneaded therewith at a rotation speed of 40 rpm for 40 minutes. The viscosity was then adjusted to 3,000±500 mPas (measured by B-type viscometer at 25° C. and 60 rpm) with deionized water to produce a slurry composition for a negative electrode mixed material layer.
[0220] The slurry composition for a negative electrode mixed material layer was applied onto the surface of copper foil of 15 μm in thickness serving as a current collector by a comma coater such as to have a coating weight of 11±0.5 mg/cm.sup.2. The copper foil having the slurry composition for a negative electrode mixed material layer applied thereon was subsequently conveyed inside an oven having a temperature of 80° C. for 2 minutes and an oven having a temperature of 110° C. for 2 minutes at a speed of 400 mm/min so as to dry the slurry composition on the copper foil and thereby obtain a negative electrode web having a negative electrode mixed material layer formed on the current collector.
[0221] Thereafter, the negative electrode mixed material layer-side of the produced negative electrode web was roll pressed with a line pressure of 11 t (tons) in an environment having a temperature of 25±3° C. to obtain a negative electrode having a negative electrode mixed material layer density of 1.60 g/cm.sup.3. The negative electrode was subsequently left in an environment having a temperature of 25±3° C. and a relative humidity of 50±5% for 1 week.
<Formation of Positive Electrode>
[0222] A slurry composition for a positive electrode mixed material layer was produced by loading 96 parts of an active material NMC111 (LiNi.sub.1/3Co.sub.1/3Mn.sub.1/3O.sub.2) based on a lithium complex oxide of Co—Ni—Mn as a positive electrode active material, 2 parts of acetylene black (produced by Denka Company Limited; product name HS-100) as a conductive material, and 2 parts of polyvinylidene fluoride (produced by Kureha Corporation; product name: KF-1100) as a binder for a positive electrode into a planetary mixer, further adding N-methyl-2-pyrrolidone (NMP) as a dispersion medium to adjust the total solid content concentration to 67%, and mixing these materials.
[0223] Next, the obtained slurry composition for a positive electrode mixed material layer was applied onto aluminum foil of 20 μm in thickness serving as a current collector by a comma coater such as to have a coating weight of 20±0.5 mg/cm.sup.2.
[0224] The aluminum foil was conveyed inside an oven having a temperature of 90° C. for 2 minutes and an oven having a temperature of 120° C. for 2 minutes at a speed of 200 mm/min so as to dry the slurry composition on the aluminum foil and thereby obtain a positive electrode web having a positive electrode mixed material layer formed on the current collector.
[0225] Thereafter, the positive electrode mixed material layer-side of the produced positive electrode web was roll pressed with a line pressure of 14 t (tons) in an environment having a temperature of 25±3° C. to obtain a positive electrode having a positive electrode mixed material layer density of 3.40 g/cm.sup.3. The positive electrode was subsequently left in an environment having a temperature of 25±3° C. and a relative humidity of 50±5% for 1 week.
<Production of Lithium Ion Secondary Battery>
[0226] The negative electrode, positive electrode, and separator were used to produce a wound cell (discharge capacity equivalent to 520 mAh) and were arranged inside aluminum packing. The inside of the aluminum packing was subsequently filled with LiPF.sub.6 solution of 1.0 M in concentration (solvent: mixed solvent of ethylene carbonate (EC)/diethyl carbonate (DEC)=3/7 (volume ratio); additive: containing 2 volume % (solvent ratio) of vinylene carbonate) as an electrolyte solution. The aluminum packing was then closed by heat sealing at a temperature of 150° C. to tightly seal an opening of the aluminum packing, and thereby produce a lithium ion secondary battery. This lithium ion secondary battery was used to evaluate cycle characteristics. The result is shown in Table 1.
Example 2
[0227] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 889.0 g (70.0%), the amount of acrylic acid as an acid group-containing monomer was changed to 152.4 g (12.0%), and the amount of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer was changed to 228.6 g (18.0%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
Example 3
[0228] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 825.5 g (65.0%), the amount of acrylic acid as an acid group-containing monomer was changed to 139.7 g (11.0%), and the amount of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer was changed to 304.8 g (24.0%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
Example 4
[0229] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 825.5 g (65.0%), the amount of acrylic acid as an acid group-containing monomer was changed to 38.1 g (3.0%), and the amount of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer was changed to 406.4 g (32.0%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
Example 5
[0230] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 806.45 g (63.5%), the amount of acrylic acid as an acid group-containing monomer was changed to 215.9 g (17.0%), and the amount of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer was changed to 247.65 g (19.5%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
Example 6
[0231] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 1219.2 g (96.0%), the amount of acrylic acid as an acid group-containing monomer was changed to 17.78 g (1.4%), and the amount of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer was changed to 33.02 g (2.6%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
Example 7
[0232] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in
[0233] Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 939.8 g (74.0%), the amount of acrylic acid as an acid group-containing monomer was changed to 203.2 g (16.0%), and the amount of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer was changed to 127.0 g (10.0%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
Example 8
[0234] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 939.8 g (74.0%), the amount of acrylic acid as an acid group-containing monomer was changed to 63.5 g (5.0%), and the amount of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer was changed to 266.7 g (21.0%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
Example 9
[0235] A water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that an aqueous solution containing a water-soluble polymer that was produced as described below was used. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
<Production of Aqueous Solution Containing Water-Soluble Polymer>
[0236] A 10 L septum-equipped flask was charged with 6,335 g of deionized water and 95 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator. These materials were heated to a temperature of 40° C., and the inside of the flask was purged with nitrogen gas at a flow rate of 100 mL/min. Next, 939.8 g (74.0%) of acrylamide as an amide group-containing monomer, 127.0 g (10.0%) of acrylic acid as an acid group-containing monomer, and 203.2 g (16.0%) of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer were mixed and were injected into the flask by a syringe. Thereafter, 100 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator was added into the flask by a syringe, and the reaction temperature was set to 60° C. Once 2 hours had passed, 50 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 47.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added in order to further raise the reaction conversion rate. Once a further 2 hours had passed, 50 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 47.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added. Two hours later, 34 g of a 5% aqueous solution of sodium nitrite as a reaction inhibitor was added into the flask and was stirred. Thereafter, the flask was cooled to 40° C. and was converted to an air atmosphere. The pH of the system was adjusted to 8.0 using 8% lithium hydroxide aqueous solution to thereby yield an aqueous solution containing a water-soluble polymer.
Example 10
[0237] A water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that an aqueous solution containing a water-soluble polymer that was produced as described below was used. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
<Production of Aqueous Solution Containing Water-Soluble Polymer>
[0238] A 10 L septum-equipped flask was charged with 6,335 g of deionized water and 285 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator. These materials were heated to a temperature of 40° C., and the inside of the flask was purged with nitrogen gas at a flow rate of 100 mL/min. Next, 939.8 g (74.0%) of acrylamide as an amide group-containing monomer, 127.0 g (10.0%) of acrylic acid as an acid group-containing monomer, and 203.2 g (16.0%) of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer were mixed and were injected into the flask by a syringe. Thereafter, 300 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator was added into the flask by a syringe, and the reaction temperature was set to 60° C. Once 2 hours had passed, 150 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 142.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added in order to further raise the reaction conversion rate. Once a further 2 hours had passed, 150 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 142.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added. Two hours later, 34 g of a 5% aqueous solution of sodium nitrite as a reaction inhibitor was added into the flask and was stirred. Thereafter, the flask was cooled to 40° C. and was converted to an air atmosphere. The pH of the system was adjusted to 8.0 using 8% lithium hydroxide aqueous solution to thereby yield an aqueous solution containing a water-soluble polymer.
Example 11
[0239] A water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that an aqueous solution containing a water-soluble polymer that was produced as described below was used. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
<Production of Aqueous Solution Containing Water-Soluble Polymer>
[0240] A 10 L septum-equipped flask was charged with 6,335 g of deionized water and 66.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator. These materials were heated to a temperature of 40° C., and the inside of the flask was purged with nitrogen gas at a flow rate of 100 mL/min. Next, 939.8 g (74.0%) of acrylamide as an amide group-containing monomer, 127.0 g (10.0%) of acrylic acid as an acid group-containing monomer, and 203.2 g (16.0%) of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer were mixed and were injected into the flask by a syringe. Thereafter, 75 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator was added into the flask by a syringe, and the reaction temperature was set to 60° C. Once 2 hours had passed, 35 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 33.3 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added in order to further raise the reaction conversion rate. Once a further 2 hours had passed, 35 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 33.3 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added. Two hours later, 34 g of a 5% aqueous solution of sodium nitrite as a reaction inhibitor was added into the flask and was stirred. Thereafter, the flask was cooled to 40° C. and was converted to an air atmosphere. The pH of the system was adjusted to 8.0 using 8% lithium hydroxide aqueous solution to thereby yield an aqueous solution containing a water-soluble polymer.
Example 12
[0241] In production of an aqueous solution containing a water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 933.45 g (73.5%), the amount of acrylic acid as an acid group-containing monomer was changed to 120.65 g (9.5%), and 215.9 g (17.0%) of 2-hydroxyethyl methacrylate was used instead of 203.2 g (16.0%) of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer. Moreover, the amount of a water dispersion containing a particulate polymer that was used in production of a slurry composition for a heat-resistant layer was changed to 3 parts of solid content. With the exception of the above, an aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 1.
Example 13
[0242] In production of an aqueous solution containing a water-soluble polymer, 2-hydroxyethyl acrylate was used instead of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer. Moreover, the amount of a water dispersion containing a particulate polymer that was used in production of a slurry composition for a heat-resistant layer was changed to 3 parts of solid content. With the exception of the above, an aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
Example 14
[0243] An aqueous solution containing a water-soluble polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the slurry composition for a heat-resistant layer, a water dispersion containing a particulate polymer was not added, and the amount of the aqueous solution containing the water-soluble polymer was changed to 4 parts of solid content. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
Example 15
[0244] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the slurry composition for a heat-resistant layer, the amount of the water dispersion containing the particulate polymer was changed to 1.3 parts of solid content. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
Example 16
[0245] An aqueous solution containing a water-soluble polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that a water dispersion containing a particulate polymer that was produced as described below was used. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
<Production of Water Dispersion Containing Particulate Polymer>
[0246] A reactor including a stirrer was supplied with 70 parts of deionized water and 0.5 parts of ammonium persulfate. The gas phase of the reactor was purged with nitrogen gas and the temperature was raised to 60° C. Meanwhile, a monomer composition was obtained in a separate vessel by mixing 50 parts of deionized water, 0.5 parts of polyoxyethylene lauryl ether (produced by Kao Corporation; product name: EMULGEN® 120 (EMULGEN is a registered trademark in Japan, other countries, or both)) as an emulsifier, 65 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer, 30 parts of styrene as another monomer, 1.7 parts of allyl glycidyl ether and 0.3 parts of allyl methacrylate as cross-linkable monomers, and 3 parts of methacrylic acid as a hydrophilic group-containing monomer.
[0247] The monomer composition was continuously added into the reactor over 4 hours to carry out polymerization. The reaction was carried out at 70° C. during the continuous addition. Once the continuous addition was complete, a further 3 hours of stirring was performed at 80° C. to complete the reaction and thereby yield a water dispersion of a particulate polymer.
[0248] The obtained water dispersion of the particulate polymer was cooled to 25° C., was subsequently adjusted to pH 8.0 through addition of sodium hydroxide aqueous solution, and then unreacted monomer was removed therefrom through introduction of steam. Thereafter, adjustment of solid content concentration was performed with deionized water while performing filtration using a 200-mesh (opening size: approximately 77 μm) screen made of stainless steel to obtain a water dispersion (solid content concentration:
[0249] 40%) containing the particulate polymer.
Example 17
[0250] An aqueous solution containing a water-soluble polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that a water dispersion containing a particulate polymer that was produced as described below was used. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
<Production of Water Dispersion Containing Particulate Polymer>
[0251] A reactor including a stirrer was supplied with 70 parts of deionized water, 0.20 parts of polyoxyethylene lauryl ether (produced by Kao Corporation; product name: EMULGEN® 120) as an emulsifier, and 0.5 parts of ammonium persulfate. The gas phase of the reactor was purged with nitrogen gas and the temperature was raised to 60° C. Meanwhile, a monomer composition was obtained in a separate vessel by mixing 50 parts of deionized water, 0.5 parts of polyoxyethylene lauryl ether (produced by Kao Corporation; product name: EMULGEN® 120) as an emulsifier, 70 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer, 25 parts of styrene as another monomer, 1.7 parts of allyl glycidyl ether and 0.3 parts of allyl methacrylate as cross-linkable monomers, and 3 parts of methacrylic acid as a hydrophilic group-containing monomer.
[0252] The monomer composition was continuously added into the reactor over 4 hours to carry out polymerization. The reaction was carried out at 70° C. during the continuous addition. Once the continuous addition was complete, a further 3 hours of stirring was performed at 80° C. to complete the reaction and thereby yield a water dispersion of a particulate polymer.
[0253] The obtained water dispersion of the particulate polymer was cooled to 25° C., was subsequently adjusted to pH 8.0 through addition of sodium hydroxide aqueous solution, and then unreacted monomer was removed therefrom through introduction of steam. Thereafter, adjustment of solid content concentration was performed with deionized water while performing filtration using a 200-mesh (opening size: approximately 77 μm) screen made of stainless steel to obtain a water dispersion (solid content concentration: 40%) containing the particulate polymer.
Example 18
[0254] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the slurry composition for a heat-resistant layer, barium sulfate particles (produced by Takehara Kagaku Kogyo Co., Ltd.; product name: TS-3; volume-average particle diameter: 0.5 μm) were used instead of alumina particles as non-conductive inorganic particles. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
Comparative Example 1
[0255] A water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that an aqueous solution containing a water-soluble polymer that was produced as described below was used. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
<Production of Aqueous Solution Containing Water-Soluble Polymer>
[0256] A 10 L septum-equipped flask was charged with a monomer composition containing 895.0 g (89.5%) of acrylamide and 15.0 g (1.5%) of dimethylacrylamide as amide group-containing monomers and 90.0 g (9.0%) of acrylic acid as an acid group-containing monomer, and also with 3,650 g of deionized water and 50 g of isopropyl alcohol, and the inside of the flask was purged with nitrogen gas at a flow rate of 100 mL/min. Next, 70 g of 5% ammonium persulfate aqueous solution and 30 g of 5% sodium bisulfite aqueous solution as polymerization initiators were added under stirring, and then the temperature was raised from room temperature to 80° C. and was held thereat for 3 hours. Thereafter, 1,620 g of deionized water was added, and the pH was adjusted to 8 with 10% sodium hydroxide aqueous solution to yield an aqueous solution containing a water-soluble polymer.
Comparative Example 2
[0257] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in
[0258] Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, acrylic acid as an acid group-containing monomer and N-hydroxyethylacrylamide as a hydroxyl group-containing monomer were not added, and the amount of acrylamide as an amide group-containing monomer was changed to 1,270 g (100%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
Comparative Example 3
[0259] A water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that an aqueous solution containing a water-soluble polymer that was produced as described below was used. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
<Production of Aqueous Solution Containing Water-Soluble Polymer>
[0260] A 10 L septum-equipped flask was charged with 6,335 g of deionized water and 95 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator. These materials were heated to a temperature of 40° C., and the inside of the flask was purged with nitrogen gas at a flow rate of 100 mL/min. Next, 635.0 g (50.0%) of acrylamide and 127.0 g (10.0%) of methacrylamide as amide group-containing monomers, 317.5 g (25.0%) of acrylic acid and 63.5 g (5.0%) of 2-acrylamido-2-methylpropane sulfonic acid as acid group-containing monomers, 63.5 g (5.0%) of 2-hydroxyethyl methacrylate as a hydroxyl group-containing monomer, and 63.5 g (5.0%) of methacrylonitrile as another monomer were mixed and were injected into the flask by a syringe. Thereafter, 100 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator was added into the flask by a syringe, and the reaction temperature was set to 60° C. Once 2 hours had passed, 50 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 47.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added in order to further raise the reaction conversion rate. Once a further 2 hours had passed, 50 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 47.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added. Two hours later, 34 g of a 5% aqueous solution of sodium nitrite as a reaction inhibitor was added into the flask and was stirred. Thereafter, the flask was cooled to 40° C. and was converted to an air atmosphere. The pH of the system was adjusted to 8.0 using 8% lithium hydroxide aqueous solution.
Comparative Example 4
[0261] A water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that an aqueous solution containing a water-soluble polymer that was produced as described below was used. Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
<Production of Aqueous Solution Containing Water-Soluble Polymer>
[0262] A 10 L septum-equipped flask was charged with 6,335 g of deionized water and 95 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator. These materials were heated to a temperature of 40° C., and the inside of the flask was purged with nitrogen gas at a flow rate of 100 mL/min. Next, 571.5 g (45.0%) of acrylamide as an amide group-containing monomer, 317.5 g (25.0%) of acrylic acid as an acid group-containing monomer, and 381.0 g (30.0%) of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer were mixed and were injected into the flask by a syringe. Thereafter, 100 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator was added into the flask by a syringe, and the reaction temperature was set to 60° C. Once 2 hours had passed, 50 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 47.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added in order to further raise the reaction conversion rate. Once a further 2 hours had passed, 50 g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 47.5 g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added. Two hours later, 34 g of a 5% aqueous solution of sodium nitrite as a reaction inhibitor was added into the flask and was stirred. Thereafter, the flask was cooled to 40° C. and was converted to an air atmosphere. The pH of the system was adjusted to 8.0 using 8% lithium hydroxide aqueous solution to thereby yield an aqueous solution containing a water-soluble polymer.
Comparative Example 5
[0263] An aqueous solution containing a water-soluble polymer, a water dispersion containing a particulate polymer, a slurry composition for a heat-resistant layer, a negative electrode, a positive electrode, a separator, and a lithium ion secondary battery were prepared or produced in the same way as in Example 1 with the exception that in production of the aqueous solution containing the water-soluble polymer, the amount of acrylamide as an amide group-containing monomer was changed to 946.15 g (74.5%), the amount of acrylic acid as an acid group-containing monomer was changed to 6.35 g (0.5%), and the amount of N-hydroxyethylacrylamide as a hydroxyl group-containing monomer was changed to 317.5 g (25.0%). Evaluations were conducted in the same manner as in Example 1. The results are shown in Table 2.
[0264] In Tables 1 and 2, shown below:
[0265] “AAm” indicates acrylamide unit;
[0266] “DMAAm” indicates dimethylacrylamide unit;
[0267] “MAAm” indicates methacrylamide unit;
[0268] “AA” indicates acrylic acid unit;
[0269] “ATBS” indicates 2-acrylamido-2-methylpropane sulfonic acid unit;
[0270] “HEAAm” indicates N-hydroxyethylacrylamide unit;
[0271] “HEMA” indicates 2-hydroxyethyl methacrylate unit;
[0272] “HEA” indicates 2-hydroxyethyl acrylate unit;
[0273] “MAN” indicates methacrylonitrile unit;
[0274] “BA” indicates n-butyl acrylate unit;
[0275] “2EHA” indicates 2-ethylhexyl acrylate unit;
[0276] “MAA” indicates methacrylic acid unit;
[0277] “AGE” indicates allyl glycidyl ether unit;
[0278] “AMA” indicates allyl methacrylate unit;
[0279] “AN” indicates acrylonitrile unit;
[0280] “ST” indicates styrene unit;
[0281] “Al.sub.2O.sub.3” indicates alumina particles; and
[0282] “BaSO.sub.4” indicates barium sulfate particles.
TABLE-US-00001 TABLE 1 Example Example Example Example Example 1 2 3 4 5 Slurry Binder Water- Amide group- Type AAm AAm AAm AAm AAm composition composition soluble containing Proportional 74 70 65 65 63.5 polymer monomer unit content [mass %] Type — — — — — Proportional — — — — — content [mass %] Acid group- Type AA AA AA AA AA containing Proportional 10 12 11 3 17 monomer unit content [mass %] Type — — — — — Proportional — — — — — content [mass %] Hydroxyl Type HEAAm HEAAm HEAAm HEAAm HEAAm group- Proportional 16 18 24 32 19.5 containing content monomer unit [mass %] Other Type — — — — — monomer unit Proportional — — — — — content [mass %] Hydroxyl group/acid group 1.00 0.94 1.37 6.68 0.72 molar ratio Weight-average molecular 500 × 10.sup.3 500 × 10.sup.3 500 × 10.sup.3 500 × 10.sup.3 500 × 10.sup.3 weight Content [parts by mass] 2 2 2 2 2 Particulate (Meth)acrylic Type BA BA BA BA BA polymer acid ester Proportional 94.2 94.2 94.2 94.2 94.2 monomer unit content [mass %] Hydrophilic Type MAA MAA MAA MAA MAA group- Proportional 2 2 2 2 2 containing content monomer unit [mass %] Cross- Type AGE AGE AGE AGE AGE linkable Proportional 1.5 1.5 1.5 1.5 1.5 monomer unit content [mass %] Type AMA AMA AMA AMA AMA Proportional 0.3 0.3 0.3 0.3 0.3 content [mass %] Other Type AN AN AN AN AN monomer unit Proportional 2 2 2 2 2 content [mass %] Glass-transition temperature −40 −40 −40 −40 −40 [° C.] Volume-average particle 0.36 0.36 0.36 0.36 0.36 diameter [μm] Content [parts by mass] 4 4 4 4 4 Non-conductive Type Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 inorganic particles Content [parts by mass] 100 100 100 100 100 Evaluation Dispersion stability A A A A B Coatability A A A B A Heat shrinkage resistance A B B B B Close adherence A A A B A Cycle characteristics A A A A A Example Example Example Example 6 7 8 9 Slurry Binder Water- Amide group- Type AAm AAm AAm AAm composition composition soluble containing Proportional 96 74 74 74 polymer monomer unit content [mass %] Type — — — — Proportional — — — — content [mass %] Acid group- Type AA AA AA AA containing Proportional 1.4 16 5 10 monomer unit content [mass %] Type — — — — Proportional — — — — content [mass %] Hydroxyl Type HEAAm HEAAm HEAAm HEAAm group- Proportional 2.6 10 21 16 containing content monomer unit [mass %] Other Type — — — — monomer unit Proportional — — — — content [mass %] Hydroxyl group/acid group 1.16 0.39 2.63 1.00 molar ratio Weight-average molecular 500 × 10.sup.3 500 × 10.sup.3 500 × 10.sup.3 1200 × 10.sup.3 weight Content [parts by mass] 2 2 2 2 Particulate (Meth)acrylic Type BA BA BA BA polymer acid ester Proportional 94.2 94.2 94.2 94.2 monomer unit content [mass %] Hydrophilic Type MAA MAA MAA MAA group- Proportional 2 2 2 2 containing content monomer unit [mass %] Cross- Type AGE AGE AGE AGE linkable Proportional 1.5 1.5 1.5 1.5 monomer unit content [mass %] Type AMA AMA AMA AMA Proportional 0.3 0.3 0.3 0.3 content [mass %] Other Type AN AN AN AN monomer unit Proportional 2 2 2 2 content [mass %] Glass-transition temperature −40 −40 −40 −40 [° C.] Volume-average particle 0.36 0.36 0.36 0.36 diameter [μm] Content [parts by mass] 4 4 4 4 Non-conductive Type Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 inorganic particles Content [parts by mass] 100 100 100 100 Evaluation Dispersion stability B B A A Coatability B B B B Heat shrinkage resistance A A A A Close adherence B A B A Cycle characteristics A A A A Example Example Example 10 11 12 Slurry Binder Water- Amide group- Type AAm AAm AAm composition composition soluble containing Proportional 74 74 73.5 polymer monomer unit content [mass %] Type — — — Proportional — — — content [mass %] Acid group- Type AA AA AA containing Proportional 10 10 9.5 monomer unit content [mass %] Type — — — Proportional — — — content [mass %] Hydroxyl Type HEAAm HEAAm HEMA group- Proportional 16 16 17 containing content monomer unit [mass %] Other Type — — — monomer unit Proportional — — — content [mass %] Hydroxyl group/acid group 1.00 1.00 0.99 molar ratio Weight-average molecular 280 × 10.sup.3 1800 × 10.sup.3 500 × 10.sup.3 weight Content [parts by mass] 2 2 2 Particulate (Meth)acrylic Type BA BA BA polymer acid ester Proportional 94.2 94.2 94.2 monomer unit content [mass %] Hydrophilic Type MAA MAA MAA group- Proportional 2 2 2 containing content monomer unit [mass %] Cross- Type AGE AGE AGE linkable Proportional 1.5 1.5 1.5 monomer unit content [mass %] Type AMA AMA AMA Proportional 0.3 0.3 0.3 content [mass %] Other Type AN AN AN monomer unit Proportional 2 2 2 content [mass %] Glass-transition temperature −40 −40 −40 [° C.] Volume-average particle 0.36 0.36 0.36 diameter [μm] Content [parts by mass] 4 4 3 Non-conductive Type Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 inorganic particles Content [parts by mass] 100 100 100 Evaluation Dispersion stability A A A Coatability A B A Heat shrinkage resistance B A B Close adherence A A A Cycle characteristics A A B
TABLE-US-00002 TABLE 2 Example Example Example Example Example 13 14 15 16 17 Slurry Binder Water- Amide group- Type AAm AAm AAm AAm AAm composition composition soluble containing Proportional 74 74 74 74 74 polymer monomer unit content [mass %] Type — — — — — Proportional — — — — — content [mass %] Acid group- Type AA AA AA AA AA containing Proportional 10 10 10 10 10 monomer unit content [mass %] Type — — — — — Proportional — — — — — content [mass %] Hydroxyl Type HEA HEAAm HEAAm HEAAm HEAAm group- Proportional 16 16 16 16 16 containing content monomer unit [mass %] Other Type — — — — — monomer unit Proportional — — — — — content [mass %] Hydroxyl group/acid group 0.99 1.00 1.00 1.00 1.00 molar ratio Weight-average molecular 500 × 10.sup.3 500 × 10.sup.3 500 × 10.sup.3 500 × 10.sup.3 500 × 10.sup.3 weight Content [parts by mass] 2 4 2 2 2 Particulate (Meth)acrylic Type BA — BA 2EHA 2EHA polymer acid ester Proportional 94.2 — 94.2 65 70 monomer unit content [mass %] Hydrophilic Type MAA — MAA MAA MAA group- Proportional 2 — 2 3 3 containing content monomer unit [mass %] Cross- Type AGE — AGE AGE AGE linkable Proportional 1.5 — 1.5 1.7 1.7 monomer unit content [mass %] Type AMA — AMA AMA AMA Proportional 0.3 — 0.3 0.3 0.3 content [mass %] Other Type AN — AN ST ST monomer unit Proportional 2 — 2 30 25 content [mass %] Glass-transition temperature −40 — −40 −25 −30 [° C.] Volume-average particle 0.36 — 0.36 0.31 0.18 diameter [μm] Content [parts by mass] 3 — 1.3 4 4 Non-conductive Type Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 inorganic particles Content [parts by mass] 100 100 100 100 100 Evaluation Dispersion stability A A A A A Coatability A A A A A Heat shrinkage resistance B A A A A Close adherence A B B A A Cycle characteristics B A A A B Example Comparative Comparative Comparative 18 Example 1 Example 2 Example 3 Slurry Binder Water- Amide group- Type AAm AAm AAm AAm composition composition soluble containing Proportional 74 89.5 100 50 polymer monomer unit content [mass %] Type — DMAAm — MAAm Proportional — 1.5 — 10 content [mass %] Acid group- Type AA AA — AA containing Proportional 10 9 — 25 monomer unit content [mass %] Type — — — ATBS Proportional — — — 5 content [mass %] Hydroxyl Type HEAAm — — HEMA group- Proportional 16 — — 5 containing content monomer unit [mass %] Other Type — — — MAN monomer unit Proportional — — — 5 content [mass %] Hydroxyl group/acid group 1.00 — — 0.10 molar ratio Weight-average molecular 500 × 10.sup.3 360 × 10.sup.3 500 × 10.sup.3 1000 × 10.sup.3 weight Content [parts by mass] 2 2 2 2 Particulate (Meth)acrylic Type BA BA BA BA polymer acid ester Proportional 94.2 94.2 94.2 94.2 monomer unit content [mass %] Hydrophilic Type MAA MAA MAA MAA group- Proportional 2 2 2 2 containing content monomer unit [mass %] Cross- Type AGE AGE AGE AGE linkable Proportional 1.5 1.5 1.5 1.5 monomer unit content [mass %] Type AMA AMA AMA AMA Proportional 0.3 0.3 0.3 0.3 content [mass %] Other Type AN AN AN AN monomer unit Proportional 2 2 2 2 content [mass %] Glass-transition temperature −40 −40 −40 −40 [° C.] Volume-average particle 0.36 0.36 0.36 0.36 diameter [μm] Content [parts by mass] 4 4 4 4 Non-conductive Type BaSO.sub.4 Al.sub.2O.sub.3 Al.sub.2O.sub.3 Al.sub.2O.sub.3 inorganic particles Content [parts by mass] 100 100 100 100 Evaluation Dispersion stability A C C C Coatability A C C C Heat shrinkage resistance A B B C Close adherence A A C A Cycle characteristics A A B A Comparative Comparative Example 4 Example 5 Slurry Binder Water- Amide group- Type AAm AAm composition composition soluble containing Proportional 45 74.5 polymer monomer unit content [mass %] Type — — Proportional — — content [mass %] Acid group- Type AA AA containing Proportional 25 0.5 monomer unit content [mass %] Type — — Proportional — — content [mass %] Hydroxyl Type HEAAm HEAAm group- Proportional 30 25 containing content monomer unit [mass %] Other Type — — monomer unit Proportional — — content [mass %] Hydroxyl group/acid group 0.75 31.29 molar ratio Weight-average molecular 1000 × 10.sup.3 500 × 10.sup.3 weight Content [parts by mass] 2 2 Particulate (Meth)acrylic Type BA BA polymer acid ester Proportional 94.2 94.2 monomer unit content [mass %] Hydrophilic Type MAA MAA group- Proportional 2 2 containing content monomer unit [mass %] Cross- Type AGE AGE linkable Proportional 1.5 1.5 monomer unit content [mass %] Type AMA AMA Proportional 0.3 0.3 content [mass %] Other Type AN AN monomer unit Proportional 2 2 content [mass %] Glass-transition temperature −40 −40 [° C.] Volume-average particle 0.36 0.36 diameter [μm] Content [parts by mass] 4 4 Non-conductive Type Al.sub.2O.sub.3 Al.sub.2O.sub.3 inorganic particles Content [parts by mass] 100 100 Evaluation Dispersion stability C A Coatability B C Heat shrinkage resistance C B Close adherence A C Cycle characteristics A B
[0283] It can be seen from Tables 1 and 2 that it was possible to form a slurry composition having excellent dispersion stability and coatability and a heat-resistant layer having excellent heat shrinkage resistance in Examples 1 to 18 in which the used binder composition contained a water-soluble polymer that included an amide group-containing monomer unit, an acid group-containing monomer unit, and a hydroxyl group-containing monomer unit and in which the proportional contents of the amide group-containing monomer unit and the acid group-containing monomer unit were within specific ranges. It can also be seen that the heat-resistant layers of Examples 1 to 18 had excellent close adherence with a substrate and could cause a secondary battery to display excellent cycle characteristics.
[0284] On the other hand, it can be seen that dispersion stability and coatability of a slurry composition could not be sufficiently ensured in Comparative Example 1 in which the used binder composition contained a water-soluble polymer that only included an amide group-containing monomer unit and an acid group-containing monomer unit.
[0285] It can also be seen that dispersion stability and coatability of a slurry composition could not be sufficiently ensured and a heat-resistant layer having excellent close adherence with a substrate could not be formed in Comparative Example 2 in which the used binder composition contained a water-soluble polymer that only included an amide group-containing monomer unit.
[0286] It can also be seen that dispersion stability and coatability of a slurry composition could not be sufficiently ensured and a heat-resistant layer having excellent heat shrinkage resistance could not be formed in Comparative Example 3 in which the used binder composition contained a water-soluble polymer in which the proportional contents of an amide group-containing monomer unit and an acid group-containing monomer unit were outside of the specific ranges.
[0287] It can also be seen that dispersion stability of a slurry composition could not be sufficiently ensured and a heat-resistant layer having excellent heat shrinkage resistance could not be formed in Comparative Example 4 in which the used binder composition contained a water-soluble polymer in which the proportional contents of an amide group-containing monomer unit and an acid group-containing monomer unit were outside of the specific ranges. It can also be seen that coatability of a slurry composition could not be sufficiently ensured and a heat-resistant layer having excellent close adherence with a substrate could not be formed in Comparative Example 5 in which the used binder composition contained a water-soluble polymer in which the proportional content of an acid group-containing monomer unit was outside of the specific range.
INDUSTRIAL APPLICABILITY
[0288] According to the present disclosure, it is possible to provide a binder composition for a non-aqueous secondary battery heat-resistant layer with which it is possible to produce a slurry composition for a non-aqueous secondary battery heat-resistant layer that has excellent dispersion stability and coatability and that can form a heat-resistant layer for a non-aqueous secondary battery having excellent heat shrinkage resistance.
[0289] Moreover, according to the present disclosure, it is possible to provide a slurry composition for a non-aqueous secondary battery heat-resistant layer that has excellent dispersion stability and coatability and that can form a heat-resistant layer for a non-aqueous secondary battery having excellent heat shrinkage resistance.
[0290] Furthermore, according to the present disclosure, it is possible to provide a heat-resistant layer for a non-aqueous secondary battery that has excellent heat shrinkage resistance and a non-aqueous secondary battery that includes this heat-resistant layer.