Secondary Battery Binder Composition for Low Initial Resistance
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Solution Overview
Problem
Existing binders for lithium-ion secondary batteries, such as polyvinylidene fluoride (PVDF) and styrene-butadiene rubber (SBR), increase the initial resistance value of the battery, posing environmental concerns and limiting battery performance.
Innovation Solution
A binder comprising a polymer compound with specific repeating units, where the total ratio of a lactone structure is less than 2 mol%, is used to reduce the initial resistance value of the secondary battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If styrene-butadiene rubber (SBR) is used as a binder to reduce environmental burden, then the binder becomes more environmentally friendly, but the initial resistance value of the secondary battery increases
Solution Approach 1:
The invention changes the chemical structure parameters of the binder by introducing specific repeating units with carboxyl groups and controlling the ratio of different repeating units. This parameter optimization allows the binder to achieve both low initial resistance and environmental friendliness by balancing electrical conductivity and adhesion properties without using conventional SBR
Solution Approach 2:
The invention creates a composite binder system by combining multiple types of repeating units (acrylic acid-based, vinyl alcohol-based, and lactone-based) in specific ratios. This composite structure synergistically provides good adhesion to active materials, sufficient electrical conductivity, and environmental compatibility, resolving the contradiction between SBR's environmental benefits and its harmful effect on initial resistance
2Reliability
If polyvinylidene fluoride (PVDF) is used as a binder, then good adhesion and electrical conductivity are achieved, but the binder requires organic solvents which increase environmental burden
Solution Approach 1:
The invention changes the solvent compatibility parameter by designing a polymer structure with specific repeating units that enable dissolution in water instead of organic solvents. The carboxyl groups and hydroxyl groups in the repeating units provide hydrophilicity, allowing the binder to be processed in environmentally friendly aqueous solutions while maintaining PVDF-like performance characteristics
Solution Approach 2:
The invention replaces expensive and environmentally problematic organic solvent systems with cheap and environmentally benign water-based systems. The aqueous processing approach eliminates the need for hazardous organic solvents while achieving comparable or superior binder performance, aligning with green chemistry principles
Data Source
AI summary
The present invention provides a binder for a secondary battery that can reduce the initial resistance value of the secondary battery. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains repeating units represented by formulae (1), (2), and (3):in formula (1), R1 is a hydrogen atom or a methyl group, and M is a hydrogen atom or an alkali metal atom; and in formula (3), R2 is a hydrogen atom or a methyl group; andwhen a total ratio of repeating units constituting the polymer compound is taken as 100 mol %, a total ratio of the repeating unit represented by formula (3) is less than 2 mol %.