Electrode Mixture Composition for Stable Viscosity and Adhesion
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Solution Overview
Problem
Existing electrode mixtures for non-aqueous electrolyte secondary batteries face challenges in maintaining viscosity stability and achieving excellent adhesion and flexibility of the electrode mixture layer to the current collector, which affects the load characteristics and performance of secondary batteries.
Innovation Solution
The electrode mixture comprises an electrode active material, an organic solvent, a binder with a fluorine-containing copolymer comprising a vinylidene fluoride unit and a fluorinated monomer unit, and an additive with a specific repeating unit, where the binder content is 0.1 to 1.6 parts by mass and the additive content is 0.001 to 0.2 parts by mass relative to the electrode active material, enhancing adhesion and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binders are used in electrode mixtures, then the electrode mixture layer can be formed, but the adhesion to current collector and flexibility are insufficient
Solution Approach 1:
The patent uses a composite binder system comprising a fluorine-containing copolymer (with vinylidene fluoride unit and fluorinated monomer unit) combined with a specific polymer additive containing amide or nitrile groups. This composite material approach resolves the contradiction by achieving superior adhesion and flexibility through the synergistic interaction between the fluorine-containing copolymer and the polymer additive, without increasing formulation complexity.
2Strength
If binder content is increased to improve adhesion, then adhesion performance improves, but viscosity increases excessively
Solution Approach 1:
The patent optimizes the binder content to a specific range (0.1 to 1.6 parts by mass per 100 parts by mass of electrode active material) and the polymer additive content to (0.001 to 0.2 parts by mass per 100 parts by mass of electrode active material). This parameter optimization resolves the contradiction by achieving adequate adhesion while maintaining stable viscosity through the enhanced performance of the fluorine-containing copolymer and polymer additive combination.
3Reliability
If conventional polymer additives are used, then the electrode mixture can be formulated, but load characteristics are insufficient
Solution Approach 1:
The patent specifies a polymer additive with particular local chemical characteristics - containing repeating units where R represents a chain or cyclic amide group, a nitrile group, or a substituted alkyl group with specific functional groups. This local quality specification (functional group type) resolves the contradiction by providing sufficient load characteristics through the specific chemical properties of the polymer additive without requiring complex overall formulation.
Data Source
AI summary
Provided is an electrode mixture including: an electrode active material; an organic solvent; a binder; and an additive; wherein the binder contains a fluorine-containing copolymer containing a vinylidene fluoride unit and a fluorinated monomer unit, provided that the vinylidene fluoride unit is excluded from the fluorinated monomer unit; the additive is a polymer material containing the following repeating unit: —[CH2—CHR]— wherein R is a chain or cyclic amide group, a nitrile group, or a substituted alkyl group formed by substituting at least one of hydrogen atoms of an alkyl group having 1 to 4 carbon atoms with a chain or cyclic amide group or a nitrile group; a content of the binder is 0.1 to 1.6 parts by mass with respect to 100 parts by mass of the electrode active material; and a content of the additive is 0.001 to 0.2 parts by mass with respect to 100 parts by mass of the electrode active material.