Solvent-Free Li-Ion Electrode Binder via Fluoropolymer Functionalization
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Solution Overview
Problem
Current Li-ion battery electrode production methods rely on organic solvents, which are environmentally harmful and costly, and solvent-free processes face challenges in achieving adequate adhesion, cohesion, and homogeneity.
Innovation Solution
A solvent-free electrode composition using a mixture of fluoropolymers, where one fluoropolymer is functionalized with carboxylic acid groups to enhance adhesion and cohesion, combined with active and conductive fillers, is deposited and consolidated using thermomechanical mixing and heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic solvents are used in electrode production, then adhesion and cohesion are improved, but environmental harm and production costs increase
Solution Approach 1:
The invention changes the chemical parameters of the binder by using fluoropolymers with different viscosities and molecular weights, and by controlling the functional group content (0.01-15 mol%), to achieve adequate adhesion and cohesion without requiring organic solvents. This parameter optimization allows solvent-free processing while maintaining electrode integrity.
Solution Approach 2:
The invention uses composite binder systems combining fluoropolymers with specific functional groups (carboxylic acid, hydroxyl, amine) to create a material that provides both adhesion to current collectors and cohesion between active material particles, replacing the need for organic solvent-based binders.
2Object-affected harmful factors
If solvent-free process is used, then environmental impact and production costs are reduced, but adhesion, cohesion, and homogeneity deteriorate
Solution Approach 1:
The invention optimizes physical parameters including binder viscosity (50-2500 kPoise), molecular weight, and functional group content to enable proper mixing, deposition, and consolidation in solvent-free conditions, achieving homogeneous electrode formation with adequate adhesion and cohesion.
Solution Approach 2:
The invention introduces functional groups at specific locations on the fluoropolymer chains to provide localized adhesion sites on current collectors and cohesion sites between particles, creating non-uniform chemical properties that enhance overall electrode integrity in solvent-free processing.
3Ease of manufacture
If binder content is reduced, then production costs are reduced, but mechanical strength deteriorates
Solution Approach 1:
The invention uses fluoropolymers containing functional groups that form strong chemical bonds with active material particles and current collectors, creating a composite structure where the binder acts as both adhesive and structural component, maintaining mechanical strength at reduced binder contents (3-10 wt%).
Solution Approach 2:
The invention changes the chemical reactivity parameters of the binder by incorporating functional groups that form strong bonds, allowing reduced binder content while maintaining or improving mechanical strength through enhanced bond energy per unit mass of binder.
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
This approach reduces binder content, improves mechanical strength, and ensures homogeneous electrode formation with enhanced adhesion and porosity control, reducing production costs and environmental impact.
Implementation Method 1
one of which bears one or more functionalities... a fluoropolymer is functionalized with carboxylic acid groups to enhance adhesion and cohesion
Implementation Method 2
deposited and consolidated using thermomechanical mixing and heat treatment
Data Source
AI summary
The present invention relates generally to the field of electrical energy storage in rechargeable secondary batteries of Li-ion type. More specifically, the invention relates to an electrode formulation for a Li-ion battery, comprising a binder based on a mixture of fluoropolymers. The invention also relates to a process for preparing electrodes using said formulation, by a technique of solvent-free deposition on a metal substrate. The invention relates finally to an electrode obtained by this process and also to Li-ion storage batteries comprising at least one such electrode.