Aqueous Binder for Lithium-Ion Electrodes
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Solution Overview
Problem
Conventional binders for lithium-ion battery electrodes face issues with oxidation degradation, high environmental load, and poor performance under high temperature and high voltage conditions, leading to deteriorated charge/discharge cycles and oxidation resistance.
Innovation Solution
A water-based binder comprising constitutional units derived from a monomer with a hydroxyl group and polyfunctional (meth)acrylate monomers, providing strong bondability and flexibility, and a highly crosslinked structure that prevents dissolution in electrolyte solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If SBR-base binder is used for positive electrode, then aqueous binder requirement is met, but oxidation degradation occurs under positive electrode environment
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by using a copolymer containing aromatic vinyl units and conjugated diene units with specific functional groups, rather than conventional SBR. This compositional change enables the binder to resist oxidation under positive electrode conditions while remaining water-based, thus resolving the contradiction between environmental friendliness and oxidation resistance.
Solution Approach 2:
The invention creates a composite binder system by combining aromatic vinyl units, conjugated diene units, and specific functional groups in a copolymer structure. This composite material approach allows the binder to simultaneously achieve aqueous compatibility and high oxidation resistance, overcoming the limitations of single-material binders like SBR.
2Reliability
If polyvinylidene fluoride and polytetrafluoroethylene binders are used, then oxidation resistance is improved, but environmental load increases due to N-methylpyrrolidone solvent
Solution Approach 1:
The invention changes the solvent parameter from N-methylpyrrolidone to water, creating a water-based binder system. The copolymer composition is specifically designed to maintain oxidation resistance while being compatible with aqueous environments, thus resolving the contradiction between oxidation resistance and environmental friendliness.
3Ease of manufacture
If conventional binders are used for high temperature conditions, then manufacturing is simplified, but charge/discharge cycle deteriorates
Solution Approach 1:
The invention changes the thermal stability parameters of the binder through the specific copolymer structure containing aromatic vinyl and conjugated diene units. This structural modification enables the binder to maintain adhesion and flexibility at high temperatures, preserving charge/discharge cycle life while keeping the manufacturing process simple and straightforward.
4Strength
If binder addition amount is increased to secure bondability, then bondability between electrical collector and active material is improved, but electrode performance deteriorates
Solution Approach 1:
The invention changes the chemical affinity parameters of the binder through the specific copolymer structure, enhancing its bonding capability per unit mass. This allows effective bondability between electrical collector and active material at lower binder concentrations, thus improving electrode performance by reducing the non-conductive binder content while maintaining strong adhesion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The binder achieves excellent bondability, flexibility, and long-term cycle life for secondary batteries, with improved heat resistance and reduced environmental impact, maintaining performance at high temperatures and high voltages.
Implementation Method 1
a binder for battery electrode, comprising a polymer comprising: (A) constitutional units derived from a monomer having a hydroxyl group, represented by general formula (1)... (B) constitutional units derived from a polyfunctional (meth)acrylate monomer
Implementation Method 2
a binder for battery electrode, comprising a polymer comprising: (A) constitutional units derived from a monomer having a hydroxyl group... excellent bondability
Data Source
AI summary
The purpose of the present invention is to provide: an aqueous binder having high adhesiveness, that in particular does not exhibit oxidative degradation in an electrode environment, and having little environmental load; and an electrode and a battery that use same. Disclosed is a battery electrode binder containing: (A) a constituent unit derived from a monomer having a hydroxyl group; and (B) a constituent unit derived from a polyfunctional! (meth)acrylate having no more than 5 functions. An electrode is prepared using this binder and is used in a battery such as a lithium-ion secondary battery.