Dispersant For Separator Of Non-Aqueous Electrolyte Battery Including Cyanoethyl Group-Containing Polymer, Separator Of Non-Aqueous Electrolyte Battery, And Non-Aqueous Electrolyte Battery

Abstract

Provided are a dispersant for a separator of a non-aqueous electrolyte battery, the dispersant including a cyanoethyl group-containing polymer, a separator of a non-aqueous electrolyte battery using the same, and a non-aqueous electrolyte battery.

Claims

1. A dispersant composition for a separator of a non-aqueous electrolyte battery, the dispersant composition comprising a cyanoethyl group-containing polymer including a first repeating unit represented by the following Chemical Formula 1, a second repeating unit represented by the following Chemical Formula 2, a third repeating unit represented by the following Chemical Formula 3, and a fourth repeating unit represented by the following Chemical Formula 4, wherein a ratio of the repeating number of the fourth repeating unit to the total repeating number of the first to fourth repeating units in the cyanoethyl group-containing polymer is 1:10000 or less: ##STR00015## in Chemical Formula 1, R1 is hydrogen or an alkyl group having 1 to 3 carbon atoms, ##STR00016## in Chemical Formula 2, R21 is hydrogen or an alkyl group having 1 to 3 carbon atoms; and R22 is an oxyethylene group, ##STR00017## in Chemical Formula 3, R31 is hydrogen or an alkyl group having 1 to 3 carbon atoms; and R32 is an oxyethylene group, ##STR00018## in Chemical Formula 4, R41 is hydrogen or an alkyl group having 1 to 3 carbon atoms; and R42 is an oxyethylene group.

2. The dispersant composition for a separator of a non-aqueous electrolyte battery according to claim 1, wherein a ratio of the repeating number of the second repeating unit to the total repeating number of the first to fourth repeating units in the cyanoethyl group-containing polymer is 0.70 or more and 0.95 or less.

3. The dispersant composition for a separator of a non-aqueous electrolyte battery according to claim 1, wherein a ratio of the repeating number of the third repeating unit to the total repeating number of the first to fourth repeating units is 0.001 or more and 0.070 or less.

4. The dispersant composition for a separator of a non-aqueous electrolyte battery according to claim 1, wherein R1, R21, R31, and R41 are the same as or different from each other, each independently hydrogen or methyl.

5. The dispersant composition for a separator of a non-aqueous electrolyte battery according to claim 1, wherein a weight average molecular weight of the cyanoethyl group-containing polymer is 100,000 g/mol to 500,000 g/mol.

6. A separator of a non-aqueous electrolyte battery, the separator comprising: a heat resistant porous layer including the dispersant composition for a separator of a non-aqueous electrolyte battery according to claim 1; and a porous substrate.

7. The separator of a non-aqueous electrolyte battery according to claim 6, wherein the heat-resistant porous layer further includes an inorganic filler.

8. The separator of a non-aqueous electrolyte battery according to claim 7, wherein the inorganic filler is selected from the group consisting of inorganic oxides, inorganic nitrides, poorly soluble ionic crystal particles, covalently bonded crystals, clay, materials derived from mineral resources, lithium titanium phosphate, and combinations thereof.

9. The separator of a non-aqueous electrolyte battery according to claim 6, wherein the porous substrate is a substrate including one or more resins selected from the group consisting of polyolefin resins, polyester resins, polyacetal resins, polyamide resins, polycarbonate resins, polyimide resins, polyetheretherketone resins, polyethersulfone resins, and combinations thereof.

10. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, the separator of a non-aqueous electrolyte battery according to claim 6, and an electrolyte solution.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0159] Hereinafter, the actions and effects of the present invention will be described in more detail with reference to the specific exemplary embodiments of the present invention. However, these exemplary embodiments are for illustrative purposes only, and the scope of the present invention is not intended to be limited thereby.

[0160] A cyanoethyl substitution ratio was determined as the ratio (%) to mole number of hydroxyl groups originally existing per a repeating unit of a polymer, after calculating the nitrogen content in cyanoethylated polyvinyl alcohol produced in the following Synthesis Example by the Kjeldahl method.

[0161] An amidoethyl substitution ratio was determined by calculating the peak area corresponding to hydrogens bound to a nitrogen atom after obtaining H.sup.1-NMR spectrum of a sample.

[0162] A carboxyethyl substitution ratio was determined by calculating the peak area corresponding to a carboxyl group (—COO—) after obtaining IR spectrum of a sample.

[0163] A weight average molecular weight was analyzed by GPC, and GPC measurement conditions are as follows:

[0164] Apparatus: Gel permeation chromatography GPC (apparatus name: Alliance e2695; manufacturer: WATERS)

[0165] Detector: Differential refractive index detector (apparatus name: W2414; manufacturer: WATERS)

[0166] Column: DMF column

[0167] Flow rate: 1 mL/min

[0168] Column temperature: 65° C.

[0169] Injection amount: 0.100 mL

[0170] Standard sample: polystyrene

[0171] An average particle diameter of the slurry was measured using a particle size analyzer (Mastersizer, Malvern).

[0172] A sedimentation rate of the slurry was measured using a LUMiSizer equipment.

EXAMPLE

[0173] Preparation of Polymer Using Acrylamide Monomer

Example 1-1

[0174] 1 part by weight of polyvinyl alcohol (PVA), 6 parts by weight of acrylonitrile (AN), 2 parts by weight of acrylamide, and 1.32 parts by weight of benzyltrimethylammonium hydroxide (3.83 wt % aqueous solution) as a catalyst were introduced into a reactor equipped with a stirrer, and allowed to react at 50° C. for 90 min.

[0175] 3 parts by weight of acetone and 0.3 parts by weight of water were added thereto, and stirred for 40 min, and then 0.088 parts by weight of acetic acid (25 wt % aqueous solution) was introduced to terminate the reaction, thereby obtaining polyvinyl alcohol, into which a cyanoethyl group and an amidoethyl group were introduced.

[0176] A substitution ratio of the cyanoethyl group was 75.3 mol %, a substitution ratio of the amidoethyl group was 4.2 mol %, and a peak corresponding to the carboxyl group was not observed in IR spectrum (Mw: 390,000).

Example 1-2

[0177] 1 part by weight of polyvinyl alcohol (PVA), 6 parts by weight of acrylonitrile (AN), 2 parts by weight of acrylamide, and 1.32 parts by weight of benzyltrimethylammonium hydroxide (5.5 wt % aqueous solution) as a catalyst were introduced into a reactor equipped with a stirrer, and allowed to react at 50° C. for 90 min.

[0178] 3 parts by weight of acetone and 0.3 parts by weight of water were added thereto, and stirred for 40 min, and then 0.088 parts by weight of acetic acid (25 wt % aqueous solution) was introduced to terminate the reaction, thereby obtaining polyvinyl alcohol, into which a cyanoethyl group and an amidoethyl group were introduced.

[0179] A substitution ratio of the cyanoethyl group was 76.2 mol %, a substitution ratio of the amidoethyl group was 3.1 mol %, and a peak corresponding to the carboxyl group was not observed in IR spectrum (Mw: 362,000).

Example 1-3

[0180] 1 part by weight of polyvinyl alcohol (PVA), 6 parts by weight of acrylonitrile (AN), 2 parts by weight of acrylamide, and 1.32 parts by weight of benzyltrimethylammonium hydroxide (6.49 wt % aqueous solution) as a catalyst were introduced into a reactor equipped with a stirrer, and allowed to react at 50° C. for 90 min.

[0181] 3 parts by weight of acetone and 0.3 parts by weight of water were added thereto, and stirred for 40 min, and then 0.088 parts by weight of acetic acid (25 wt % aqueous solution) was introduced to terminate the reaction, thereby obtaining polyvinyl alcohol, into which a cyanoethyl group and an amidoethyl group were introduced.

[0182] A substitution ratio of the cyanoethyl group was 74.5 mol %, a substitution ratio of the amidoethyl group was 3.5 mol %, and a peak corresponding to the carboxyl group was not observed in IR spectrum (Mw: 402,000).

Example 1-4

[0183] 1 part by weight of polyvinyl alcohol (PVA), 6 parts by weight of acrylonitrile (AN), 3 parts by weight of acrylamide, and 1.32 parts by weight of benzyltrimethylammonium hydroxide (3.83 wt % aqueous solution) as a catalyst were introduced into a reactor equipped with a stirrer, and allowed to react at 50° C. for 90 min.

[0184] 3 parts by weight of acetone and 0.3 parts by weight of water were added thereto, and stirred for 40 min, and then 0.088 parts by weight of acetic acid (25 wt % aqueous solution) was introduced to terminate the reaction, thereby obtaining polyvinyl alcohol, into which a cyanoethyl group and an amidoethyl group were introduced.

[0185] A substitution ratio of the cyanoethyl group was 74.3 mol %, a substitution ratio of the amidoethyl group was 5.0 mol %, and a peak corresponding to the carboxyl group was not observed in IR spectrum (Mw: 399,000).

[0186] Characteristics of the cyanoethyl group-containing polymers prepared in Examples 1 to 4 are summarized in Table 1 below.

TABLE-US-00001 TABLE 1 Cyanoethyl Amide Carboxyl substitution substitution substitution ratio ratio ratio (mol %) (mol %) (mol %) Example 1-1 75.3 4.2 0 (Not detected) Example 1-2 76.2 3.1 0 (Not detected) Example 1-3 74.5 3.5 0 (Not detected) Example 1-4 74.3 5.0 0 (Not detected)

[0187] Preparation of Polymer Left for Predetermined Time after Michael Reaction

[0188] Preparation of Polymer

[0189] 30 g of polyvinyl alcohol (PVA) and 135 g of acrylonitrile (AN) were introduced into a reactor equipped with a stirrer, and maintained at 50° C.

[0190] Primarily, 6.6 g of benzyltrimethylammonium hydroxide (4.18 wt % aqueous solution) was introduced thereto, and maintained for 50 min.

[0191] Secondarily, 33.3 g of benzyltrimethylammonium hydroxide (4.18 wt % aqueous solution) was introduced thereto, and maintained for 50 min.

[0192] 72 g of acetone and 9 g of water were added thereto, and allowed to react for 10 hr while collecting product samples according to the reaction time.

[0193] The product samples thus obtained were confirmed to have a weight average molecular weight of about 250,000 g/mol.

[0194] The results are summarized in Table 2 below, and the time summarized in the following Table is based on the time point when water and acetone were introduced.

[0195] As Comparative Example, cyanoethylated polyvinyl alcohol having a weight average molecular weight of about 250,000 g/mol, a cyanoethyl substitution ratio of about 83 mol %, and an amide substitution ratio of 0 mol % was prepared.

TABLE-US-00002 TABLE 2 Cyanoethyl Amide Carboxyl substitution substitution substitution ratio ratio ratio Hour(s) (mol %) (mol %) (mol %) Example 2-1 0 84.9 0.31 0 (Not detected) Example 2-2 1 86.7 0.77 0 (Not detected) Example 2-3 3 82.3 1.43 0 (Not detected) Example 2-4 5 80.3 2.08 0 (Not detected) Example 2-5 6 79.8 2.27 0 (Not detected) Example 2-6 8 75.9 2.68 0 (Not detected) Example 2-7 10 76.4 2.61 0 (Not detected) Example 2-8 12 81.4 3.81 0 (Not detected) Comparative — 83.0 0 0 (Not detected) Example 1

[0196] Preparation of Slurry

[0197] To 320 parts by weight of acetone, 1 part by weight of each polyvinyl alcohol-based polymer obtained in Examples and Comparative Example, and 7 parts by weight of polyvinylidene fluoride-hexafluoropropylene as a binder were added, and dissolved at 50° C. for 12 hr. 72 parts by weight of Al.sub.2O.sub.3 having a number average diameter of 500 nm as inorganic particles was added thereto, and each slurry was prepared using a ball mill method. Particle diameter characteristics and sedimentation rates of the slurries were measured.

[0198] Measurement of Particle Diameter Characteristic

[0199] A particle diameter of each slurry composition prepared above was measured using a particle size analyzer.

[0200] Measurement of Sedimentation Rate

[0201] To examine dispersibility of the binder, the slurries prepared in Examples and Comparative Example were rotated at 1,000 rpm using a dispersion stability analyzer (LUMiSizer), and the sedimentation rate of alumina was measured at 25° C., and the results are shown in Table 3 below. For reference, as the dispersibility of the cyanoethyl group-containing polymer is better, alumina is dispersed well and its sedimentation is slow.

[0202] The measurement results are summarized in Table 3 below.

[0203] Manufacture of Electrode for Adhesion Test

[0204] Artificial graphite, carbon black, CMC, and a binder were mixed with water at a weight ratio of 96:1:1:2 to prepare a negative electrode slurry. The negative electrode slurry was coated on a copper foil having a thickness of 50 μm, dried at 80° C. for 1 hr or longer, and then pressed to manufacture a negative electrode.

[0205] The cyanoethyl group-containing polymer prepared above and the slurry of inorganic particles were applied to one side of a polyethylene porous substrate using a doctor blade and dried to prepare a separator having a porous coating layer.

[0206] The negative electrode and the separator were put in a lamination equipment to be laminated with each other, and this sample was peeled at a speed of 100 mm/min using a UTM equipment, and the force required to peel the adhesion surface between the electrode and the separator was measured.

[0207] The measurement results are summarized in Table 3 below.

TABLE-US-00003 TABLE 3 Sedimentation rate Electrode adhesion (based on 1000 rpm) (gf/15 mm) Example 1-1 9.0 96 Example 1-2 9.3 94 Example 1-3 9.3 93 Example 1-4 8.8 101 Example 2-1 12.0 78 Example 2-2 11.7 80 Example 2-3 10.0 82 Example 2-4 9.8 88 Example 2-5 9.5 90 Example 2-6 9.4 92 Example 2-7 9.4 92 Example 2-8 9.2 95 Comparative 12.7 76 Example 1

[0208] Referring to the above table, the slurries prepared by using the cyanoethyl group-containing polymer according to one exemplary embodiment of the present invention had superior dispersibility, as compared with that of Comparative Example, and therefore, they were able to well disperse alumina, and accordingly, sedimentation thereof was slower than that of Comparative Example.

[0209] In addition, it was clearly confirmed that the separators manufactured using the cyanoethyl group-containing polymer showed very excellent adhesion between the electrode and the separator. In particular, it was clearly confirmed that Example 1-4 realized the adhesive strength 30% higher than that of Comparative Example.