Binder Composition for High-Voltage Electrochemical Device
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Solution Overview
Problem
Conventional binder compositions for electrochemical devices suffer significant reductions in discharge capacity when subjected to repeated cycles of charge and discharge at high voltage, necessitating improved high-voltage cycle characteristics.
Innovation Solution
A binder composition comprising a copolymer with a nitrile group-containing monomer unit, an acidic group-containing monomer unit, and a basic group-containing monomer unit, where the nitrile unit constitutes 70.0 mol % to 99.0 mol % and the acidic and basic units together form 0.8 mol % to 10.0 mol %, enhancing adhesion and oxidization resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binder compositions are used, then the electrode can be formed and initial discharge capacity is achieved, but significant reductions in discharge capacity occur when repeatedly charged and discharged at high voltage
Solution Approach 1:
The binder composition uses a copolymer comprising multiple monomer units (nitrile group-containing, acidic group-containing, and basic group-containing monomer units) to create a composite material structure. This composite polymer structure provides both adhesion to the active material and resistance to oxidization at high voltage, resolving the contradiction between initial performance and cycle stability.
Solution Approach 2:
The invention specifies precise compositional parameters for the copolymer: nitrile group-containing monomer unit at 70.0-99.0 mol%, acidic group-containing monomer unit at 0.1-10.0 mol%, and basic group-containing monomer unit at 0.1-10.0 mol%. By controlling these compositional parameters within specific ranges, the binder achieves optimal balance between adhesion and oxidization resistance, maintaining discharge capacity during high-voltage cycling.
2Strength
If the proportion of nitrile group-containing monomer unit is increased to improve adhesion, then adhesion between active material and binder is enhanced, but the total proportion of acidic and basic group-containing monomer units must be maintained to prevent oxidization
Solution Approach 1:
The copolymer structure assigns different functional roles to different monomer units: nitrile group-containing units (70.0-99.0 mol%) provide adhesion through coordination with metal oxides, while acidic group-containing units (0.1-10.0 mol%) and basic group-containing units (0.1-10.0 mol%) provide oxidization resistance through neutralization reactions. This local functional differentiation within the polymer chain resolves the contradiction between adhesion and oxidization resistance.
Solution Approach 2:
The acidic and basic group-containing monomer units act as intermediaries that protect the nitrile group-containing units from oxidization at high voltage. The acidic groups can neutralize basic sites that would otherwise promote oxidization, while basic groups can neutralize acidic byproducts, creating a protective environment that maintains both adhesion and oxidization resistance simultaneously.
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 proposed binder composition improves high-voltage cycle characteristics by maintaining adhesion and preventing cell bulging, thereby enhancing the performance of electrochemical devices.
Implementation Method 1
increase adhesion between the electrode active material and the current collector
Implementation Method 2
preventing oxidization
Data Source
AI summary
A disclosed binder composition comprises a copolymer which comprises a nitrile group-containing monomer unit, an acidic group-containing monomer unit and a basic group-containing monomer unit, wherein the proportion of the nitrile group-containing monomer unit in the copolymer is 70.0 mol % or more and 99.0 mol % or less, and wherein the total proportion of the acidic group-containing monomer unit and the basic group-containing monomer unit in the copolymer is 0.8 mol % or more and 10.0 mol % or less.