NEGATIVE ELECTRODE BINDER FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, AND NEGATIVE ELECTRODE FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

• Main Author: KURIHARA HITOSHI
• Format: Patent
• Language: English; Japanese
• Published: 20.09.2018
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

PROBLEM TO BE SOLVED: To provide a negative electrode binder for a nonaqueous electrolyte secondary battery, which enables the improvement of the coulomb efficiency and life characteristic of a nonaqueous electrolyte secondary battery.SOLUTION: A binder for forming a mixture layer 3 of a negative electrode 1 for a nonaqueous electrolyte secondary battery together with an active material comprises: a chief binder consisting of a polymer having a molecular weight of 1,000,000-5,000,000 and a repeating unit consisting of an ethylenic unsaturated carboxylic acid compound; and an auxiliary binder consisting of a polymer having a molecular weight of 1000-10,000. The auxiliary binder contains: a copolymer including, in its repeating unit, (a1) an ethylenic unsaturated carboxylic acid compound, and (b) an ethylenic unsaturated compound including an alkyl carboxylic acid ester group having an alkyl part with C1-10 or (a2) an ethylenic unsaturated carboxylic acid compound having an alkyl part with C1-10 on α carbon of a carboxyl group; or a polymer including, as a repeating unit, (a2) the ethylenic unsaturated carboxylic acid compound and (a3) an ethylenic unsaturated carboxylic acid compound other than that.SELECTED DRAWING: Figure 1 【課題】非水電解質二次電池のクーロン効率及び寿命特性が改善できる非水電解質二次電池用負極バインダの提供。【解決手段】活物質と共に非水電解質二次電池用負極１の合剤層３を構成するバインダで、分子量が１００万〜５００万で、繰り返し単位がエチレン性不飽和カルボン酸化合物であるポリマーからなる主バインダと、分子量が１０００〜１万のポリマーである補助バインダと、を含み、補助バインダが、エチレン性不飽和カルボン酸化合物（ａ１）と、Ｃ１〜１０のアルキル部位を有するアルキルカルボン酸エステル基を含むエチレン性不飽和化合物（ｂ）、またはカルボキシル基のα炭素上にＣ１〜１０のアルキル部位を有するエチレン性不飽和カルボン酸化合物（ａ２）、とを、繰り返し単位中に含む共重合体、あるいは（ａ２）とそれ以外のエチレン性不飽和カルボン酸化合物（ａ３）を繰り返し単位として含む重合体からなる。【選択図】図１