Composite Binder Composition for Lithium Battery Electrodes
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Solution Overview
Problem
Lithium batteries face challenges in achieving high energy density and lifespan due to the trade-off between the amount of binder, which affects the dispersibility, binding force, and flexibility of electrode active materials and conductive agents, with existing binders either swelling excessively or providing inadequate properties.
Innovation Solution
A binder composition combining a tetrafluoroethylene polymer binder, a vinylidene fluoride binder, and a non-fluoropolymer binder with an acryl monomer-derived unit, which balances flexibility, binding force, and dispersibility, thereby enhancing the cyclic characteristics of lithium batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the amount of binder is decreased to increase energy density, then energy density is improved, but dispersibility and binding force of electrode active material and conductive agent deteriorate
Solution Approach 1:
The patent uses a composite binder system combining fluoropolymer binder (polyvinylidene fluoride) and non-fluoropolymer binder (acrylonitrile-acrylic acid-alkylacrylate copolymer) in specific weight ratios (fluoropolymer: 30-70%, non-fluoropolymer: 30-70%). This composite approach allows the fluoropolymer to provide structural stability and low swelling while the non-fluoropolymer enhances dispersibility and binding force, achieving both high energy density and reliable electrode integrity with reduced total binder content.
2Stability of the object's composition
If fluoropolymer binder is used to reduce swelling and maintain electrode structure, then electrode structure stability is improved, but dispersibility of conductive agent and binding force of electrode plate deteriorate
Solution Approach 1:
The patent applies local quality by assigning different functional roles to different binder components: the fluoropolymer binder (polyvinylidene fluoride) specifically provides low swelling and electrode structure stability, while the non-fluoropolymer binder (acrylonitrile-acrylic acid-alkylacrylate copolymer) specifically provides dispersibility of conductive agent and binding force. This functional differentiation allows each component to excel at its designated property without compromise.
3Reliability
If non fluoropolymer binder is used to improve dispersibility and binding force, then dispersibility and binding force are improved, but swelling with respect to electrolytic solution increases excessively
Solution Approach 1:
The patent uses the fluoropolymer binder (polyvinylidene fluoride) as a counterbalancing component that compensates for the excessive swelling tendency of the non-fluoropolymer binder. The fluoropolymer's low swelling characteristics counteract the high swelling of the acrylonitrile-acrylic acid-alkylacrylate copolymer, resulting in a composite binder system with controlled, moderate swelling that maintains both high binding force and acceptable volume stability.
4Reliability
If binder amount is increased to improve flexibility and binding force, then flexibility and binding force are improved, but energy density decreases
Solution Approach 1:
The patent optimizes the weight ratio parameters of the binder components to achieve the desired balance. Specifically, the fluoropolymer binder is maintained at 30-70% and the non-fluoropolymer binder at 30-70%, with preferred ranges of fluoropolymer: 40-60% and non-fluoropolymer: 40-60%. This parameter optimization ensures sufficient flexibility and binding force while minimizing total binder content to maximize energy density.
Data Source
AI summary
In an aspect, a binder composition for a secondary battery including a first fluoropolymer binder including a tetrafluoroethylene polymer binder, a second fluoropolymer binder including a vinylidene fluoride binder, and a non fluoropolymer binder is provided.