Cross-linked Binder for Lithium Battery Electrode Stability
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in maintaining electrode stability and cycle-life characteristics, particularly with Si-based and Sn-based negative active materials that experience repeated expansion and shrinkage during charge and discharge, leading to deteriorated performance.
Innovation Solution
A binder composition comprising a cross-linked compound of polyacrylic acid substituted with an alkali cation and polyvinyl alcohol is developed, which improves phase stability and cross-linking ratio, enhancing the binding properties and cycle-life characteristics of lithium batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional binder is used to provide adherence of active material, then the electrode can be fabricated, but the cycle-life characteristics and electrode stability deteriorate due to repeated expansion and shrinkage of Si-based and Sn-based negative active materials
Solution Approach 1:
The patent uses a composite binder system comprising polyacrylic acid substituted with alkali cations (such as Li+, Na+, K+, or NH4+) combined with polyvinyl alcohol. This composite material provides both strong adhesion to active materials and flexibility to accommodate the expansion and shrinkage of Si-based and Sn-based negative active materials during charge-discharge cycles, thereby improving both cycle-life characteristics and electrode stability simultaneously
Solution Approach 2:
The patent modifies the chemical and physical parameters of the binder by substituting polyacrylic acid with alkali cations, which changes the pH, ionic conductivity, and binding properties of the binder. This parameter change enables the binder to maintain electrode integrity under the mechanical stress caused by volume changes of silicon-based and tin-based active materials, resolving the contradiction between adhesion strength and flexibility
2Quantity of substance
If Si-based and Sn-based negative active materials are used to increase energy density, then the battery capacity improves, but the electrode stability deteriorates due to repeated expansion and shrinkage during charge and discharge
Solution Approach 1:
The patent applies a binder composition beforehand that is specifically designed to cushion and accommodate the expansion and shrinkage of Si-based and Sn-based active materials. The polyacrylic acid substituted with alkali cations and polyvinyl alcohol combination creates a flexible matrix that预先 (in advance) prepares the electrode structure to handle volume changes, preventing deterioration and maintaining electrode stability throughout the battery's operational cycles
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 composition significantly improves the stability and cycle-life characteristics of rechargeable lithium batteries by increasing viscosity and cross-linking ratio, leading to better electrode adherence and prolonged battery performance.
Implementation Method 1
a binder composition for a rechargeable lithium battery including a cross-linked compound of polyacrylic acid substituted with an alkali cation, and polyvinyl alcohol
Data Source
AI summary
Disclosed are a binder composition for a rechargeable lithium battery including a cross-linked compound of polyacrylic acid substituted with an alkali cation and polyvinyl alcohol and an electrode and rechargeable lithium battery including the same. The cross-linked compound of polyacrylic acid and polyvinyl alcohol is obtained by heating polyacrylic acid and polyvinyl alcohol to effect a cross-linking reaction via esterification. The cross-linked compound of polyvinyl alcohol and polyacrylic acid substituted with an alkali cation may improve phase stability of a binder, and has high cross-linking ratio, thereby providing for excellent performance of a rechargeable lithium battery.