ELECTROCHEMICAL APPARATUS, ELECTRONIC APPARATUS, AND PREPARATION METHOD OF ELECTROCHEMICAL APPARATUS
20230238585 · 2023-07-27
Assignee
Inventors
Cpc classification
Y02E60/10
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y02P70/50
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H01M10/0525
ELECTRICITY
International classification
H01M4/62
ELECTRICITY
H01M10/0525
ELECTRICITY
Abstract
An electrochemical apparatus includes a positive electrode. The positive electrode includes a current collector, a first material layer, and a second material layer. The second material layer is disposed on at least one surface of the current collector, and the first material layer is disposed between the current collector and the second material layer. The first material layer includes a leveling agent. A difference between the maximum value and the minimum value of thickness of the first material layer is less than or equal to 3 μm. The obtained positive electrode has high uniformity in thickness, and there is strong adhesion between the current collector and the first material layer, and between the second material layer and the first material layer.
Claims
1. An electrochemical apparatus, comprising: a positive electrode; the positive electrode comprises a current collector, a first material layer, and a second material layer; the second material layer is disposed on at least one surface of the current collector, the first material layer is disposed between the current collector and the second material layer; and a difference between a maximum value and a minimum value of thickness of the first material layer is less than or equal to 3 μm.
2. The electrochemical apparatus according to claim 1, wherein the first material layer comprises a leveling agent, and the leveling agent is a polymer with a weight-average molecular weight of less than or equal to 50,000.
3. The electrochemical apparatus according to claim 2, wherein the leveling agent comprises at least one of a polymer of olefin derivatives, a carboxylate polymer, a siloxane polymer, an enoate polymer, an alcohol polymer, or an ether polymer.
4. The electrochemical apparatus according to claim 2, wherein the leveling agent comprises at least one of a sodium carboxylate polymer, a polymer of oxygen-containing propylene hydrocarbon derivatives, or polysiloxane.
5. The electrochemical apparatus according to claim 2, wherein the first material layer further comprises an active material, a binder, and a conductive agent; wherein based on a total mass of the first material layer, a mass percentage of the active material ranges from 50% to 98.89%, a mass percentage of the binder ranges from 1% to 20%, a mass percentage of the conductive agent ranges from 0.1% to 20%, and a mass percentage of the leveling agent ranges from 0.01% to 10%.
6. The electrochemical apparatus according to claim 5, wherein the binder comprises at least one of a copolymer of propylene hydrocarbon derivatives, polyacrylates, an acrylonitrile multipolymer, or a carboxymethyl cellulose salt.
7. The electrochemical apparatus according to claim 6, wherein the binder comprises a polymer formed by polymerization of at least one monomer of acrylonitrile, acrylic salt, acrylamide, or acrylate.
8. The electrochemical apparatus according to claim 1, wherein a thickness of the first material layer ranges from 0.05 μm to 20 μm.
9. The electrochemical apparatus according to claim 1, wherein a resistance of a fully charged positive electrode is greater than 10Ω.
10. The electrochemical apparatus according to claim 5, wherein a median particle size D.sub.v99 of the active material ranges from 0.01 μm to 19.9 μm.
11. The electrochemical apparatus according to claim 5, wherein the conductive agent comprises at least one of lamellar, reticular, linear, or zero-dimensional conductive agents.
12. The electrochemical apparatus according to claim 1, wherein a thickness of the second material layer ranges from 20 μm to 200 μm.
13. The electrochemical apparatus according to claim 2, wherein the leveling agent comprises polyethoxy propoxy propylene hydrocarbon.
14. The electrochemical apparatus according to claim 5, wherein the conductive agent comprises at least one of graphene, reticular graphite fiber, carbon nanotubes, Ketjen black, graphite fiber, or nano-particle conductive carbon.
15. A method for preparing the electrochemical apparatus of claim 1, comprising: forming the first material layer and the second material layer in sequence on at least one surface of the current collector, wherein the difference between a maximum value and a minimum value of the thickness of the first material layer is less than or equal to 3 μm.
16. An electronic apparatus, comprising: an electrochemical apparatus, the electrochemical apparatus comprises a positive electrode, the positive electrode comprises a current collector, a first material layer, and a second material layer; the second material layer is disposed on at least one surface of the current collector, the first material layer is disposed between the current collector and the second material layer, and a difference between a maximum value and a minimum value of thickness of the first material layer is less than or equal to 3 μm.
17. The electronic apparatus according to claim 16, wherein the first material layer comprises a leveling agent, and the leveling agent is a polymer with a weight-average molecular weight of less than or equal to 50,000.
18. The electronic apparatus according to claim 17, wherein the leveling agent comprises at least one of a sodium carboxylate polymer, a polymer of oxygen-containing propylene hydrocarbon derivatives, or polysiloxane.
19. The electronic apparatus according to claim 17, wherein the first material layer further comprises an active material, a binder, and a conductive agent; wherein based on a total mass of the first material layer, a mass percentage of the active material ranges from 50% to 98.89%, a mass percentage of the binder ranges from 1% to 20%, a mass percentage of the conductive agent ranges from 0.1% to 20%, and a mass percentage of the leveling agent ranges from 0.01% to 10%.
20. The electronic apparatus according to claim 16, wherein a thickness of the first material layer ranges from 0.05 μm to 20 μm.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] To describe the technical solutions in this application and the prior art more clearly, the following briefly describes the accompanying drawings required for describing some embodiments and the prior art. Apparently, the accompanying drawings in the following description show merely some embodiments of this application.
[0052]
[0053]
[0054]
[0055]
[0056]
DETAILED DESCRIPTION
[0057] To make the objectives, technical solutions, and advantages of this application clearer, the following further details this application with reference to the accompanying drawings and embodiments. Apparently, the described embodiments are merely some but not all of the embodiments of this application.
[0058] It should be noted that in the specific embodiments of this application, an example in which a lithium-ion battery is used as an electrochemical apparatus is used to illustrate this application. However, the electrochemical apparatus in this application is not limited to the lithium-ion battery.
[0059]
[0060]
[0061]
[0062] The following further details some embodiments of this application by using examples and comparative examples. Various tests and evaluations were performed in the following methods. In addition, unless otherwise specified, “percentage” and “%” are based on weight.
[0063] Test Method and Device
[0064] Thickness Difference Test for First Material Layer:
[0065] (1) The electrode plate coated with the first material layer was removed from a finished battery cell in an environment of (25±3°) C. A residual electrolyte was wiped off a surface of the electrode plate with dust-free paper.
[0066] (2) The electrode plate coated with the first material layer was cut by using plasma to obtain a cross section of the electrode plate.
[0067] (3) The cross section of the electrode plate obtained in (2) was observed by using an SEM, and a thickness of the first material layer on one surface was tested. A distance between adjacent test points ranged from 2 mm to 3 mm. At least 15 different points were tested, and an average value of thicknesses at all test points was recorded as the thickness of the first material layer.
[0068] Weight-Average Molecular Weight Test:
[0069] The gel permeation chromatography (GPC) method was used to test the weight-average molecular weight of the leveling agent and the binder. In this application, the weight-average molecular weight means an average molecular weight based on mass statistics.
[0070] Adhesion Test:
[0071] A Gotech tensile machine was used to test the adhesion between the first material layer and the current collector by using the 90° angle method: the electrode plate provided with the first material layer in the finished lithium-ion battery was cut into a strip-shaped sample with a size of 20 mm×60 mm, where a width and a length of the sample could be adjusted according to an actual situation. The first material layer at one end of the sample was adhered to a steel plate by using a double-sided adhesive tape along a length direction of the sample, and an adhesive length was not less than 40 mm. Then the steel plate was fixed at a corresponding position of the Gotech tensile machine. The other end of the sample not adhered to the steel plate was pulled up, and the electrode plate sample was put into a clamping head by using a connecting part or the electrode plate sample was directly put into the clamping head. An included angle between the part of the sample that was pulled up and the steel plate was 90°. The clamping head pulled the electrode plate at a speed of 5 mm/min to separate the first material layer from the current collector, and finally an average value of the tension measured in a stable range was recorded as the adhesion between the first material layer and the current collector.
[0072] Test of D.sub.v99 of Inorganic Particle
[0073] A laser particle size analyzer was used to test D.sub.v99 of inorganic particles. D.sub.v99 indicates an inorganic particle size where the cumulative distribution by volume reaches 99% as counted from the small particle size side.
[0074] Pass Rate of Nail Penetration Test:
[0075] The lithium-ion battery under test was charged to a voltage of 4.45 V (that is, full-charge voltage) at a constant current of 0.05 C, and then charged to a current of 0.025 C (cutoff current) at a constant voltage of 4.45 V, so that the lithium-ion battery reached a fully charged state. The appearance of the lithium-ion battery before the test was recorded. The battery was subjected to a nail penetration test in an environment of 25±3° C. A diameter of a steel nail was 4 mm, a penetration speed was 30 mm/s, and a nail penetration position was on a side of the lithium-ion battery. After the test was carried out for 3.5 min or a temperature of a surface of an electrode assembly dropped to 50° C., the test was stopped. With 10 lithium-ion batteries as one group, status of the lithium-ion batteries was observed during the test. That the lithium-ion batteries neither caught fire nor exploded was used as the criterion.
Example 1
[0076] (1) Preparation of Binder
[0077] Distilled water was added into a reactor, and the reactor was started for stirring. After nitrogen was introduced for deoxidization for 2 h, the following monomers: acrylonitrile, sodium acrylate, and acrylamide were added to the reactor at a mass ratio of 45:45:10. The reactor was heated to 65° C. in an inert atmosphere and maintained such temperature. Then 20% ammonium persulfate solution was added as an initiator to start a reaction. After 22 hours, the precipitate was taken out and lye was added to neutralize pH to 6.5. A mass ratio of the distilled water, the monomer and the initiator was 89.5:10:0.5. After the reaction, reaction products were filtered, washed, dried, crushed, and screened to obtain a binder.
[0078] (2) Preparation of Positive Electrode Plate
[0079] Lithium iron phosphate serving as the positive electrode active material, the binder obtained in step (1), nano-particle conductive carbon serving as the conductive agent, carbon nanotubes serving as the conductive agent, and the polyethoxy propoxy propylene hydrocarbon serving as the leveling agent were mixed at a mass ratio of 95.5:3:0.7:0.5:0.3, and then N-methylpyrrolidone (NMP) was added as the solvent to prepare a slurry stirred uniform with a solid content of 30%. The slurry was applied evenly to the positive electrode current collector aluminum foil with a thickness of 10 μm, and dried at 90° C. to obtain the first material layer with a thickness of 5 μm. D.sub.v99 of the lithium iron phosphate was 4 μm. The weight-average molecular weight of the polyethoxy propoxy propylene hydrocarbon was 20,000.
[0080] Lithium cobaltate (LCO) serving as a positive electrode active material, polyvinylidene fluoride (PVDF) serving as a binder, conductive carbon black serving as a conductive agent, and carbon nanotubes serving as a conductive agent were mixed at a mass ratio of 97.7:1.3:0.5:0.5, and then N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry stirred uniform with a solid content of 75%. The slurry was applied evenly to the first material layer, and dried at 90° C. to obtain the second material layer with a thickness of 85 μm.
[0081] The foregoing steps were repeated on the other surface of the positive electrode plate to obtain a positive electrode plate with two surfaces coated. After coating was completed, the positive electrode plate was cut into a sheet-shaped material with a size of 74 mm×867 mm and then welded with tabs for later use.
[0082] (3) Preparation of Negative Electrode Plate
[0083] Graphite serving as a negative electrode active material, a styrene-butadiene polymer, and sodium carboxymethyl cellulose were mixed at a mass ratio of 97.5:1.3:1.2, with deionized water added as a solvent, to prepare a slurry stirred uniform with a solid content of 70%. The slurry was uniformly applied on a negative electrode current collector copper foil with a thickness of 10 μm, dried at 110° C., and cold pressed to obtain the negative electrode plate with a single surface coated with a negative electrode active material layer, where the negative electrode active material layer was 150 μm in thickness.
[0084] The foregoing steps were repeated on the other surface of the negative electrode plate to obtain a negative electrode plate with two surfaces coated. After coating was completed, the negative electrode plate was cut into a sheet-shaped material with a size of 76 mm×851 mm and then welded with tabs for later use.
[0085] (4) Preparation of Electrolyte
[0086] In a dry argon atmosphere, organic solvents ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate were mixed at a mass ratio of EC:EMC:DEC=30:50:20 to obtain an organic solution, and then a lithium salt lithium hexafluorophosphate was added to the organic solvents for dissolving and uniform mixing, to obtain an electrolyte with a lithium salt concentration of 1.15 mol/L.
[0087] (5) Preparation of Separator
[0088] Aluminum oxide and polyvinylidene fluoride were mixed at a mass ratio of 90:10, and dissolved into deionized water to form a ceramic slurry with a solid content of 50%. Then, the ceramic slurry was uniformly applied to one side of a porous substrate (polyethylene with a thickness of 7 μm, an average pore diameter of 0.073 μm, and 26% porosity) by using the micro gravure coating method, and then dried to obtain a double-layer structure of the ceramic coating and the porous substrate. A thickness of the ceramic coating was 50 μm.
[0089] The polyvinylidene fluoride (PVDF) and polyacrylate were mixed at a mass ratio of 96:4, and dissolved into deionized water to form a polymer slurry with a solid content of 50%. Then, the polymer slurry was uniformly applied to two surfaces of the double-layer structure of the ceramic coating and the porous substrate by using the micro gravure coating method, and then dried to obtain a separator. A thickness of one layer of the coating formed by the polymer slurry was 2 μm.
[0090] (6) Preparation of Lithium-Ion Battery
[0091] The positive electrode plate, the separator, and the negative electrode plate prepared above were stacked in order, so that the separator was sandwiched between the positive electrode plate and negative electrode plate for separation, and was wound to obtain an electrode assembly. The electrode assembly was put into an aluminum-plastic film packaging bag, and was dehydrated at 80° C., and the prepared electrolyte was injected. A lithium-ion battery was obtained after processes such as vacuum sealing, standing, formation, and shaping.
Example 2
[0092] Example 2 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the leveling agent was selected from polycarboxylic acid sodium, and a mass ratio of the lithium iron phosphate and the polycarboxylic acid sodium was 94.8:1.
Example 3
[0093] Example 3 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the leveling agent was selected from polysiloxane, and a mass ratio of the lithium iron phosphate and the polysiloxane was 95.6:0.2.
Example 4
[0094] Example 4 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the leveling agent was selected from methyl polyacrylate, and a mass ratio of the lithium iron phosphate and the methyl polyacrylate was 95.5:0.3.
Example 5
[0095] Example 5 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the leveling agent was selected from polypropylene alcohol, and a mass ratio of the lithium iron phosphate and the polypropylene alcohol was 96.8:2.
Example 6
[0096] Example 6 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the leveling agent was selected from polyethylene ether, and a mass ratio of the lithium iron phosphate and the polyethylene ether was 87.8:8.
Example 7
[0097] Example 7 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polyethoxy propoxy propylene hydrocarbon was 95.79:0.01.
Example 8
[0098] Example 8 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polyethoxy propoxy propylene hydrocarbon was 95.75:0.05.
Example 9
[0099] Example 9 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polyethoxy propoxy propylene hydrocarbon was 95.7:0.1.
Example 10
[0100] Example 10 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polyethoxy propoxy propylene hydrocarbon was 95.5:0.4.
Example 11
[0101] Example 11 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polyethoxy propoxy propylene hydrocarbon was 95.3:0.5.
Example 12
[0102] Example 12 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polyethoxy propoxy propylene hydrocarbon was 95:0.8.
Example 13
[0103] Example 13 was the same as Example 2 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polycarboxylic acid sodium was 92.8:3.
Example 14
[0104] Example 14 was the same as Example 2 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polycarboxylic acid sodium was 90.8:5.
Example 15
[0105] Example 15 was the same as Example 2 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polycarboxylic acid sodium was 87.8:8.
Example 16
[0106] Example 16 was the same as Example 2 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polycarboxylic acid sodium was 85.8:10.
Example 17
[0107] Example 17 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the weight-average molecular weight of the polyethoxy propoxy propylene hydrocarbon serving as the leveling agent was 5,000.
Example 18
[0108] Example 18 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the weight-average molecular weight of the polyethoxy propoxy propylene hydrocarbon serving as the leveling agent was 30,000.
Example 19
[0109] Example 19 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the weight-average molecular weight of the polyethoxy propoxy propylene hydrocarbon serving as the leveling agent was 50,000.
Example 20
[0110] Example 20 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polyethoxy propoxy propylene hydrocarbon was 95.6:0.2.
Example 21
[0111] Example 21 was the same as Example 20 except that during the preparation of the positive electrode plate in step (2), the positive electrode active material was selected from lithium iron manganese phosphate.
Example 22
[0112] Example 22 was the same as Example 20 except that during the preparation of the positive electrode plate in step (2), the positive electrode active material was selected from lithium manganate oxide.
Example 23
[0113] The Example 23 was the same as Example 1 except that the preparation of the positive electrode plate in step (2) was that: the lithium iron manganese phosphate, the binder obtained in step (1), the carbon nanotubes, and the polyethoxy propoxy propylene hydrocarbon were mixed at a mass ratio of 96.6:3:0.2:0.2, and then N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry stirred uniform with a solid content of 30%; and the slurry was applied evenly to the positive electrode current collector aluminum foil with a thickness of 10 and dried at 90° C. to obtain the first material layer with a thickness of 0.06 and D.sub.v99 of the lithium iron phosphate was 0.02 μm.
Example 24
[0114] Example 24 was the same as Example 23 except that during the preparation of the positive electrode plate in step (2), D.sub.v99 of the lithium iron phosphate was 0.06 μm, and the thickness of the first material layer was 0.15 μm.
Example 25
[0115] Example 25 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the positive electrode active material was selected from lithium iron manganese phosphate; a mass ratio of the binder obtained in step (1), the lithium iron manganese phosphate, the nano-particle conductive carbon, the carbon nanotubes, and the polyethoxy propoxy propylene hydrocarbon was 96:3:0.3:0.5:0.2; the thickness of the first material layer was 2 μm; and D.sub.v99 of the lithium iron manganese phosphate was 0.5 μm.
Example 26
[0116] Example 26 was the same as Example 25 except that during the preparation of the positive electrode plate in step (2), the thickness of the first material layer was 3 μm, and D.sub.v99 of the lithium iron manganese phosphate was 1 μm.
Example 27
[0117] Example 27 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the thickness of the first material layer was 5 μm, and D.sub.v99 of the lithium iron manganese phosphate was 3 μm.
Example 28
[0118] Example 28 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the thickness of the first material layer was 9 μm, and D.sub.v99 of the lithium iron manganese phosphate was 7 μm.
Example 29
[0119] Example 29 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the thickness of the first material layer was 13 μm, and D.sub.v99 of the lithium iron manganese phosphate was 11 μm.
Example 30
[0120] Example 30 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the thickness of the first material layer was 17 μm, and D.sub.v99 of the lithium iron manganese phosphate was 15 μm.
Example 31
[0121] Example 31 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the thickness of the first material layer was 19.5 μm, and D.sub.v99 of the lithium iron manganese phosphate was 18 μm.
Example 32
[0122] Example 32 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the thickness of the first material layer was 20 μm, and D.sub.v99 of the lithium iron manganese phosphate was 19.9 μm.
Example 33
[0123] Example 33 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the conductive agent was selected from graphene.
Example 34
[0124] Example 34 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the conductive agent was selected from reticular graphite fiber.
Example 35
[0125] Example 35 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the conductive agent was selected from Ketjen black.
Example 36
[0126] Example 36 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the conductive agent was selected from graphite fiber.
Example 37
[0127] Example 37 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the carbon nanotubes were replaced with the reticular graphite fiber.
Example 38
[0128] Example 38 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the conductive agent was selected from the reticular graphite fiber, and a mass ratio of the lithium iron manganese phosphate, the binder obtained in step (1), the reticular graphite fiber, the polyethoxy propoxy propylene hydrocarbon was 98.7:1:0.1:0.2.
Example 39
[0129] Example 39 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the conductive agent was selected from the carbon nanotubes, and a mass ratio of the lithium iron manganese phosphate, the binder obtained in step (1), the carbon nanotubes, the polyethoxy propoxy propylene hydrocarbon was 98.3:1:0.5:0.2.
Example 40
[0130] Example 40 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 96.2:0.1:0.5.
Example 41
[0131] Example 41 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 96:0.3:0.5.
Example 42
[0132] Example 42 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 95.4:0.9:0.5.
Example 43
[0133] Example 43 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 95.2:1.1:0.5.
Example 44
[0134] Example 44 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 95:1.3:0.5.
Example 45
[0135] Example 45 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 94.8:1.5:0.5.
Example 46
[0136] Example 46 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 96:0.5:0.3.
Example 47
[0137] Example 47 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 95.8:0.5:0.5.
Example 48
[0138] Example 48 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 95.6:0.5:0.7.
Example 49
[0139] Example 49 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 95.4:0.5:0.9.
Example 50
[0140] Example 50 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, nano-particle conductive carbon, and the carbon nanotubes was 5.2:0.5:1.1.
Example 51
[0141] Example 51 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the carbon nanotubes were removed, and a mass ratio of the lithium iron manganese phosphate and nano-particle conductive carbon was 95.3:1.5.
Example 52
[0142] Example 52 was the same as Example 51 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the nano-particle conductive carbon was 94.8:2.
Example 53
[0143] Example 53 was the same as Example 51 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, the nano-particle conductive carbon, and the binder was 86.8:5:8.
Example 54
[0144] Example 54 was the same as Example 51 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, the nano-particle conductive carbon, and the binder was 79.8:10:10.
Example 55
[0145] Example 55 was the same as Example 51 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate, the nano-particle conductive carbon, and the binder was 71.8:15:13.
Example 56
[0146] Example 56 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), a mass ratio of the lithium iron manganese phosphate, the nano-particle conductive carbon, the carbon nanotubes, and the binder was 59.8:15:5:20.
Example 57
[0147] Example 57 was the same as Example 21 except that during the preparation of the binder in step (1), the binder was selected from sodium polyacrylate.
Example 58
[0148] Example 58 was the same as Example 21 except that during the preparation of the binder in step (1), the binder was selected from polyacrylamide.
Example 59
[0149] Example 59 was the same as Example 21 except that during the preparation of the binder in step (1), the mass ratio of the acrylonitrile, the sodium acrylate, and the acrylamide was 30:60:10.
Example 60
[0150] Example 60 was the same as Example 21 except that during the preparation of the binder in step (1), the mass ratio of the acrylonitrile, the sodium acrylate, and the acrylamide was 30:10:60.
Example 61
[0151] Example 61 was the same as Example 21 except that during the preparation of the binder in step (1), the mass ratio of the acrylonitrile, the sodium acrylate, and the acrylamide was 55:35:10.
Example 62
[0152] Example 62 was the same as Example 21 except that during the preparation of the binder in step (1), the mass ratio of the acrylonitrile, the sodium acrylate, and the acrylamide was 55:10:35.
Example 63
[0153] Example 63 was the same as Example 21 except that during the preparation of the binder in step (1), the mass ratio of the acrylonitrile, the sodium acrylate, and the acrylamide was 70:20:10.
Example 64
[0154] Example 64 was the same as Example 18 except that during the preparation of the binder in step (1), the following monomers: the acrylonitrile, the sodium acrylate, the acrylamide, and acrylate were added to the reactor at a mass ratio of 42:45:10:3 to prepare the binder.
Example 65
[0155] Example 65 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 97.6:1.
Example 66
[0156] Example 66 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 96.6:2.
Example 67
[0157] Example 67 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 94.6:4.
Example 68
[0158] Example 68 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 93.6:5.
Example 69
[0159] Example 69 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 90.6:8.
Example 70
[0160] Example 70 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 88.6:10.
Example 71
[0161] Example 71 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 86.6:12.
Example 72
[0162] Example 72 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 83.6:15.
Example 73
[0163] Example 73 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 80.6:18.
Example 74
[0164] Example 74 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron manganese phosphate and the binder obtained in step (1) was 78.6:20.
Comparative Example 1
[0165] Comparative Example 1 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the polyethoxy propoxy propylene hydrocarbon serving as the leveling agent was not included, a mass ratio of the lithium iron manganese phosphate, the binder obtained in step (1), the nano-particle conductive carbon, the carbon nanotubes was 95.8:3:0.7:0.5.
Comparative Example 2
[0166] Comparative Example 2 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the mass ratio of the lithium iron phosphate and the polyethoxy propoxy propylene hydrocarbon was 95.795:0.005.
Comparative Example 3
[0167] Comparative Example 3 was the same as Example 1 except that during the preparation of the positive electrode plate in step (2), the leveling agent was selected from polypropylene alcohol, and a mass ratio of the lithium iron phosphate and the polypropylene alcohol was 80.8:15.
Comparative Example 4
[0168] Comparative Example 4 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the positive electrode active material was selected from lithium cobaltate.
Comparative Example 5
[0169] Comparative Example 5 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), the positive electrode active material was selected from the lithium iron phosphate, and a mass ratio of the lithium iron phosphate and the nano-particle conductive carbon was 70.6:25.
Comparative Example 6
[0170] Comparative Example 6 was the same as Example 21 except that during the preparation of the positive electrode plate in step (2), a mass ratio of the lithium iron phosphate and the binder obtained in step (1) was 75.6:23.
TABLE-US-00001 TABLE 1 Preparation parameters and test results of Examples 1 to 19 and Comparative Examples 1 to 3 Difference between Resistance Weight- maximum of fully Pass rate of average value and charged vertical Percentage molecular minimum value positive side nail of weight of of thickness of electrode penetration Leveling leveling leveling first material plate tests at 90° agent agent agent layer (μm) (Ω) (passes/total) Example 1 Polyethoxy 0.30% 20,000 1.2 30 19/20 propoxy propylene hydrocarbon Example 2 Polycarboxylic 1.00% 20,000 2.0 30 15/20 acid sodium Example 3 Polysiloxane 0.20% 20,000 2.8 30 15/20 Example 4 Methyl 0.30% 20,000 2.5 30 15/20 polyacrylate Example 5 Polypropylene 2.00% 20,000 2.5 30 15/20 alcohol Example 6 Polyethylene 8.00% 20,000 3.0 30 15/20 ether Example 7 Polyethoxy 0.01% 20,000 2.9 30 15/20 propoxy propylene hydrocarbon Example 8 Polyethoxy 0.05% 20,000 2.8 30 15/20 propoxy propylene hydrocarbon Example 9 Polyethoxy 0.10% 20,000 2 30 15/20 propoxy propylene hydrocarbon Example 10 Polyethoxy 0.40% 20,000 1.5 30 19/20 propoxy propylene hydrocarbon Example 11 Polyethoxy 0.50% 20,000 1.5 30 19/21 propoxy propylene hydrocarbon Example 12 Polyethoxy 0.80% 20,000 2.0 30 15/20 propoxy propylene hydrocarbon Example 13 Polycarboxylic 3.00% 20,000 2.0 30 17/20 acid sodium Example 14 Polycarboxylic 5.00% 20,000 2.5 30 15/20 acid sodium Example 15 Polypropylene 8.00% 20,000 3.0 30 15/20 alcohol Example 16 Polypropylene 10.00% 20,000 3.0 30 15/20 alcohol Example 17 Polyethoxy 0.30% 5,000 2.0 30 19/20 propoxy propylene hydrocarbon Example 18 Polyethoxy 0.30% 30,000 1.5 30 19/20 propoxy propylene hydrocarbon Example 19 Polyethoxy 0.30% 50,000 1.8 30 19/20 propoxy propylene hydrocarbon Comparative / / / 5 30 9/20 Example 1 Comparative Polyethoxy 0.005% 20,000 4 30 10/20 Example 2 propoxy propylene hydrocarbon Comparative Polyethoxy 15.00% 20,000 5 30 9/20 Example 3 propoxy propylene hydrocarbon
TABLE-US-00002 TABLE 2 Preparation parameters and test results of Examples 20 to 74 and Comparative Examples 4 to 6 Percentage Mass Adhesion D.sub.v99 of con- per- Thick- between Full- Pass rate Active Mass of active Conductive ductive centage ness first charge of vertical material percentage material agent agent Binder of binder of first material resistance side nail in first of active in first in first in first in first in first material layer of positive penetration material material material material material material material layer and electrode tests at 90° layer in first layer layer layer layer layer (μm) current (Ω) (passes/total) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 280 30 19/20 20 iron particle 0.5% acrylonitrile phosphate conductive (45%) + sodium carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 280 30 19/20 21 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 280 30 19/20 22 manganate particle 0.5% acrylonitrile oxide conductive (45%) + sodium carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 96.6% 0.02 Carbon 0.2% Polymer of 3% 0.06 300 20 12/20 23 iron nanotubes acrylonitrile manganese (45%) + sodium phosphate acrylate (45%) + acrylamide (10%) Example Lithium 96.6% 0.06 Carbon 0.2% Polymer of 3% 0.15 300 15 14/20 24 iron nanotubes acrylonitrile manganese (45%) + sodium phosphate acrylate (45%) + acrylamide (10%) Example Lithium 96.0% 0.5 Nano- 0.3% + Polymer of 3% 2 300 20 19/20 25 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 96.0% 1 Nano- 0.3% + Polymer of 3% 3 280 25 19/20 26 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 3 Nano- 0.7% + Polymer of 3% 5 280 30 19/20 27 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 7 Nano- 0.7% + Polymer of 3% 9 280 30 19/20 28 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 11 Nano- 0.7% + Polymer of 3% 13 280 35 19/20 29 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 15 Nano- 0.7% + Polymer of 3% 17 280 40 19/20 30 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 18 Nano- 0.7% + Polymer of 3% 19.5 280 45 19/20 31 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 19.9 Nano- 0.7% + Polymer of 3% 20 280 45 19/20 32 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 4 Graphene 1.2% Polymer of 3% 5 280 40 19/20 33 iron acrylonitrile manganese (45%) + sodium phosphate acrylate (45%) + acrylamide (10%) Example Lithium 95.6% 4 Reticular 1.2% Polymer of 3% 5 280 20 19/20 34 iron graphite acrylonitrile manganese fiber (45%) + sodium phosphate acrylate (45%) + acrylamide (10%) Example Lithium 95.6% 4 Ketjen 1.2% Polymer of 3% 5 280 30 19/20 35 iron black acrylonitrile manganese (45%) + sodium phosphate acrylate (45%) + acrylamide (10%) Example Lithium 95.6% 4 Graphite 1.2% Polymer of 3% 5 280 30 19/20 36 iron fiber acrylonitrile manganese (45%) + sodium phosphate acrylate (45%) + acrylamide (10%) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 280 25 19/20 37 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate reticular (45%) + graphite acrylamide fiber (10%) Example Lithium 98.7% 4 Reticular 0.1% Polymer of 1% 5 201 50 12/20 38 iron graphite acrylonitrile manganese fiber (45%) + sodium phosphate acrylate (45%) + acrylamide (10%) Example Lithium 98.3% 4 Carbon 0.5% Polymer of 1% 5 201 45 11/20 39 iron nanotubes acrylonitrile manganese (45%) + sodium phosphate acrylate (45%) + acrylamide (10%) Example Lithium 96.2% 4 Nano- 0.1% + Polymer of 3% 5 280 40 19/20 40 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 96% 4 Nano- 0.3% + Polymer of 3% 5 280 35 19/20 41 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.4% 4 Nano- 0.9% + Polymer of 3% 5 280 30 19/20 42 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.2% 4 Nano- 1.1% + Polymer of 3% 5 280 25 19/20 43 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.0% 4 Nano- 1.3% + Polymer of 3% 5 280 20 17/20 44 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 94.8% 4 Nano- 1.5% + Polymer of 3% 5 280 15 15/20 45 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 96.0% 4 Nano- 0.5% + Polymer of 3% 5 280 35 19/20 46 iron particle 0.3% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.8% 4 Nano- 0.5% + Polymer of 3% 5 280 30 19/20 47 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 4 Nano- 0.5% + Polymer of 3% 5 280 25 19/20 48 iron particle 0.7% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.4% 4 Nano- 0.5% + Polymer of 3% 5 280 20 17/20 49 iron particle 0.9% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.2% 4 Nano- 0.5% + Polymer of 3% 5 280 15 15/20 50 iron particle 1.1% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.3% 4 Nano- 1.5% Polymer of 3% 5 280 30 19/20 51 iron particle acrylonitrile manganese conductive (45%) + sodium phosphate carbon acrylate (45%) + acrylamide (10%) Example Lithium 94.8% 4 Nano- 2.0% Polymer of 3% 5 280 25 19/20 52 iron particle acrylonitrile manganese conductive (45%) + sodium phosphate carbon acrylate (45%) + acrylamide (10%) Example Lithium 86.8% 4 Nano- 5% Polymer of 8% 5 280 30 19/20 53 iron particle acrylonitrile manganese conductive (45%) + sodium phosphate carbon acrylate (45%) + acrylamide (10%) Example Lithium 79.8% 4 Nano- 10% Polymer of 10% 5 280 30 19/20 54 iron particle acrylonitrile manganese conductive (45%) + sodium phosphate carbon acrylate (45%) + acrylamide (10%) Example Lithium 71.8% 4 Nano- 15% Polymer of 13% 5 280 30 19/20 55 iron particle acrylonitrile manganese conductive (45%) + sodium phosphate carbon acrylate (45%) + acrylamide (10%) Example Lithium 59.8% 4 Nano- 15% + 5% Polymer of 20% 5 280 30 19/20 56 iron particle acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 95.6% 4 Nano- 0.7% + Sodium 3% 5 230 30 17/20 57 iron particle 0.5% polyacrylate manganese conductive phosphate carbon + carbon nanotubes Example Lithium 95.6% 4 Nano- 0.7% + Polyacrylamide 3% 5 230 30 17/20 58 iron particle 0.5% manganese conductive phosphate carbon + carbon nanotubes Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 230 30 17/20 59 iron particle 0.5% acrylonitrile manganese conductive (30%) + sodium phosphate carbon + acrylate carbon (60%) + nanotubes acrylamide (10%) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 230 30 17/20 60 iron particle 0.5% acrylonitrile manganese conductive (30%) + sodium phosphate carbon + acrylate carbon (10%) + nanotubes acrylamide (60%) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 260 30 19/20 61 iron particle 0.5% acrylonitrile manganese conductive (55%) + sodium phosphate carbon + acrylate carbon (35%) + nanotubes acrylamide (10%) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 260 30 19/20 62 iron particle 0.5% acrylonitrile manganese conductive (55%) + sodium phosphate carbon + acrylate carbon (10%) + nanotubes acrylamide (35%) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 230 30 17/20 63 iron particle 0.5% acrylonitrile manganese conductive (70%) + sodium phosphate carbon + acrylate carbon (20%) + nanotubes acrylamide (10%) Example Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 230 30 17/20 64 iron particle 0.5% acrylonitrile manganese conductive (42%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) + acrylate (3%) Example Lithium 97.6% 4 Nano- 0.7% + Polymer of 1% 5 201 20 11/20 65 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 96.6% 4 Nano- 0.7% + Polymer of 2% 5 230 20 15/20 66 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 94.6% 4 Nano- 0.7% + Polymer of 4% 5 280 30 19/20 67 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 93.6% 4 Nano- 0.7% + Polymer of 5% 5 290 30 19/20 68 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 90.6% 4 Nano- 0.7% + Polymer of 8% 5 300 35 19/20 69 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 88.6% 4 Nano- 0.7% + Polymer of 10% 5 310 40 19/20 70 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 86.6% 4 Nano- 0.7% + Polymer of 12% 5 310 45 19/20 71 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 83.6% 4 Nano- 0.7% + Polymer of 15% 5 250 50 19/20 72 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 80.6% 4 Nano- 0.7% + Polymer of 18% 5 210 55 19/20 73 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Example Lithium 78.6% 4 Nano- 0.7% + Polymer of 20% 5 201 60 19/20 74 iron particle 0.5% acrylonitrile manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Comparative Lithium 95.6% 4 Nano- 0.7% + Polymer of 3% 5 280 8 0/20 Example cobaltate particle 0.5% acrylonitrile 4 conductive (45%) + sodium carbon + acrylate carbon (45%) + nanotubes acrylamide (10%) Comparative Lithium 71.8% 4 Nano- 25% Polymer of 3% 5 280 9 0/20 Example iron particle acrylonitrile 5 phosphate conductive (45%) + sodium carbon acrylate (45%) + acrylamide (10%) Comparative Lithium 75.60% 4 Nano- 0.7% + Polymer of 23% 5 160 30 8/20 Example iron particle 0.5% acrylonitrile 6 manganese conductive (45%) + sodium phosphate carbon + acrylate carbon (45%) + nanotubes acrylamide (10%)
[0171] It can be learned from Examples 1 to 19 and Comparative Examples 1 to 3 in Table 1 that the pass rate of vertical side nail penetration tests at 90° of the lithium-ion battery with the positive electrode of this application is significantly higher than that of the lithium-ion battery provided in the comparative examples. This indicates that the safety and reliability of the lithium-ion battery provided in this application are significantly improved.
[0172] It can also be learned from Examples 1 to 19 and Comparative Examples 1 to 3 in Table 1 that a difference between the maximum value and the minimum value of a thickness of the first material layer of the positive electrode plate provided in this application is smaller than that of the positive electrode plate provided in the comparative examples. This indicates that the first material layer on the positive electrode plate provided in the application has better uniformity in thickness.
[0173] It can also be learned from Examples 1 to 19 and Comparative Examples 1 to 3 in Table 1 that the positive electrode plate provided in this application can improve the safety and the reliability of the lithium-ion battery in this application, provided that the full-charge resistance falls within the protection scope of this application.
[0174] It can be learned from Examples 20 to 74 and Comparative Example 4 in Table 2 that the pass rate of vertical side nail penetration tests at 90° of the lithium-ion battery with the positive electrode plate of this application is significantly higher than that of the lithium-ion battery provided in the comparative examples. A possible reason may be that all of the lithium iron phosphate, the lithium iron manganese phosphate, and the lithium manganate oxide have greater full-charge resistance than the lithium cobaltate, and are less likely to catch fire or explode when a steel nail passes through. This shows that the safety and the reliability of the lithium-ion battery provided in this application are improved.
[0175] It can be learned from Examples 23 to 32 in Table 2 that with the increase of D.sub.v99 of the active material in the first material layer, the lithium-ion battery has a high pass rate of the nail penetration tests. This shows that provided that D.sub.v99 of the active material falls within the protection scope of this application, a lithium-ion battery with good safety performance can be obtained.
[0176] It can be learned from Examples 65 to 74 and Comparative Example 6 in Table 2 that provided that with a percentage of the binder in the first material layer within the protection scope of this application, the lithium-ion battery with the positive electrode in this application has a high pass rate of the nail penetration tests, thereby improving the safety and the reliability of the lithium-ion battery.
[0177] It can be learned from Examples 20 to 74 and Comparative Examples 4 to 5 in Table 2 that the full-charge resistance of the positive electrode plate provided in this application falls within the protection scope of this application, while the full-charge resistance in Comparative Examples 4 and 5 fall outside the protection scope of this application. A possible reason is that resistance of the lithium cobaltate in Comparative Example 4 is lower, and a percentage of the conductive agent in Comparative Example 5 is higher, thereby resulting in a zero pass rate of the nail penetration tests in Comparative Examples 4 and 5. This shows that the full-charge resistance of the positive electrode plate provided in this application falling within the protection scope of this application can improve the pass rate of the nail penetration tests of the lithium-ion battery, thereby improving the safety and reliability of the lithium-ion battery.
[0178] In conclusion, the positive electrode plate provided in this application has high uniformity in thickness, and there is strong adhesion between the current collector and the first material layer, and between the second material layer and the first material layer. The positive electrode plate is applied to the lithium-ion battery, so that probability of safety accidents caused by external forces such as impact or puncture can be effectively reduced, thereby improving the safety and reliability of the lithium-ion battery.
[0179] The foregoing descriptions are merely preferred embodiments of this application, but are not intended to limit this application. Any modification, equivalent replacement, or improvement made without departing from the spirit and principle of this application shall fall within the protection scope of this application.