Electrode Binder Composition for Low-Viscosity High-Solid Slurries
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Solution Overview
Problem
Conventional electrode production methods for electrochemical elements, such as lithium ion secondary batteries, face challenges in maintaining electrochemical properties and mechanical strength due to the use of high viscosity binders and dispersants, which can lead to deterioration of the electrode composite layer's detachment and bending resistance.
Innovation Solution
A binder composition comprising specific structural units, represented by general formulas (I) and (II), is used in a liquid composition for electrodes, optimizing the composition ratio to enhance binding properties and bending resistance while minimizing the usage of dispersants and binders, thereby improving the electrode's peel strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high solid content concentration liquid composition is used to improve productivity, then the binder viscosity increases to 10³-10⁴ mPa·s, but this causes deterioration of electrode composite layer detachment and bending resistance
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by introducing a specific structural unit with a tertiary amino group (formula I) in combination with structural unit (b) (formula II). This compositional parameter change enables the binder to achieve effective binding properties at lower concentrations (0.1-10 mass%) while maintaining low viscosity, thus resolving the contradiction between productivity and strength
Solution Approach 2:
The invention creates a composite binder system by combining structural unit (a) containing a tertiary amino group with structural unit (b) in a specific ratio (0.1:9.9 to 4:9.6). This composite structure synergistically improves both the binding efficiency and mechanical properties of the electrode composite layer, allowing high productivity without sacrificing detachment and bending resistance
2Reliability
If the usage amounts of dispersant and binder are reduced to maintain electrochemical properties, then the binding strength and bending resistance of the electrode composite layer deteriorate
Solution Approach 1:
The invention changes the chemical structure parameter of the binder by incorporating structural unit (a) with a tertiary amino group, which enhances the binder's interaction with active material particles. This parameter change increases binding efficiency per unit mass, allowing reduced binder content (0.1-10 mass%) while maintaining both electrochemical properties and mechanical strength
Solution Approach 2:
The tertiary amino group in structural unit (a) acts as an intermediary that enhances the interaction between the binder and active material particles. This intermediary function improves binding efficiency, enabling reduced binder usage while maintaining adequate binding strength and bending resistance
Data Source
AI summary
A binder used in a liquid composition containing at least one of a positive electrode active material and a solid electrolyte is provided. The binder includes a structural unit (a) and a structural unit (b) each having specific chemical structures, and a composition ratio (a:b) of the structural unit (a) and the structural unit (b) ranges from “more than 0 mol %:less than 100 mol %” to “100 mol % or less:0 mol % or more”.