Modified Polyacrylic Acid Binder for Low-Swelling Electrode Plates
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Solution Overview
Problem
Lithium-ion batteries face challenges with excessive cell swelling force due to electrode plate rebound, which affects their service life and performance.
Innovation Solution
A modified polyacrylic acid polymer material is developed, featuring a specific structural formula and preparation method through polymerization of alkaline metal salts, polyethylene glycol acrylate monoester, acrylic acid, and acrylonitrile, to act as a binder that reduces electrode plate rebound and cell swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the coating surface density and compacted density of the electrode plate are increased to achieve higher energy density, then the energy density of the lithium-ion battery is improved, but the rebound amount of the electrode plate in the Z-direction increases, causing excessive swelling force and reduced service life
Solution Approach 1:
The invention modifies the chemical composition parameters of the binder by incorporating polyacrylic acid and its derivatives with specific molecular weight ranges (10,000-1,000,000) and controlled degrees of neutralization (50-100%). This parameter optimization allows the binder to provide sufficient adhesion at high coating densities while simultaneously reducing electrode plate rebound and swelling force, thus resolving the contradiction between energy density and service life
Solution Approach 2:
The invention creates a composite binder system combining polyacrylic acid, its derivatives (such as polyacrylamide, polyacrylonitrile), and crosslinking agents. This composite material approach synergistically enhances both the adhesive properties needed for high energy density and the mechanical flexibility required to minimize rebound and swelling, thereby improving both energy density and service life simultaneously
2Quantity of substance
If silicon materials are introduced into the active material selection to improve energy density, then the capacity of the battery is improved, but the swelling force and rebound of the electrode plate increase, affecting long-term stability
Solution Approach 1:
The modified polyacrylic acid binder acts as an intermediary material between the silicon-based active material particles and the electrode structure. The binder's flexible polymer chains and crosslinked network structure accommodate the volume expansion of silicon during lithiation while maintaining electrode integrity, thus enabling high capacity silicon materials to be used without compromising electrode plate stability
Solution Approach 2:
The invention optimizes the molecular weight and functional group composition of the polyacrylic acid binder to specifically address silicon material expansion. By controlling the degree of polymerization and introducing appropriate crosslinking density, the binder provides sufficient mechanical support to constrain silicon expansion while maintaining electrochemical performance, thereby resolving the stability issue
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 modified polyacrylic acid polymer binder effectively reduces the rebound of the electrode plate, decreases the cell swelling force during cycling, and enhances the overall life and performance of lithium-ion batteries.
Implementation Method 1
a modified polyacrylic acid polymer material capable of being used as a binder in lithium-ion batteries to alleviate problems related to easy swelling during cell cycling and low battery life
Implementation Method 2
the rebound amount of the electrode plate in the Z-direction... the excessive swelling force of the cell caused by the rebound of the electrode plate
Data Source
AI summary
This application relates to a binder, an electrode plate, a secondary battery, and an electric apparatus. A modified polyacrylic acid polymer material has the following structural features. The foregoing modified polyacrylic acid polymer material employs polymerization of four monomers: an acrylic acid, an alkaline metal salt of acrylic acid, a polyethylene glycol acrylate monoester, and acrylonitrile, and is capable of acting as a binder, fully coating the active material in the process of mixing with the active material, lowering the rebound of the electrode plate under extreme design conditions, reducing the cell expansion force during cycling, and increasing the cell life.