Solvent-Free Li-Ion Electrode Formulation for Binder Adhesion
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Solution Overview
Problem
Existing Li-ion battery electrode production methods rely on volatile and toxic organic solvents, leading to environmental issues and high production costs, and there is a need for solvent-free processes that maintain electrode integrity and performance.
Innovation Solution
A solvent-free electrode composition using a mixture of fluoropolymers with different melt viscosities for binders, combined with active and conductive fillers, is applied to a metal substrate and consolidated through heat or thermomechanical treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF binder is used with organic solvents like NMP, then good adhesion and electrochemical stability are achieved, but environmental toxicity and production costs increase
Solution Approach 1:
The invention extracts and eliminates the harmful organic solvent (NMP) from the electrode manufacturing process while retaining the essential binding function. The solvent-free process removes the toxic component completely, achieving both environmental safety and functional performance.
Solution Approach 2:
The invention changes the physical state parameters of the binder system by transitioning from a solvent-based slurry to a solvent-free powder formulation. This parameter change eliminates the harmful solvent while maintaining the binder's adhesion and electrochemical stability through optimized fluoropolymer selection and processing conditions.
2Object-affected harmful factors
If solvent-free process is used, then environmental impact and production costs are reduced, but electrode cohesion and adhesion may deteriorate
Solution Approach 1:
The invention uses composite fluoropolymer formulations combining different fluorinated polymers in specific ratios to achieve optimal mechanical properties without solvent. The composite structure provides both adhesion to current collector and cohesion within the electrode matrix, maintaining strength in the solvent-free process.
Solution Approach 2:
The invention optimizes processing parameters including heat treatment temperature, pressure, and duration to ensure proper binder activation and electrode consolidation in the solvent-free process. These parameter adjustments compensate for the absence of solvent, ensuring adequate cohesion and adhesion.
3Ease of manufacture
If binder content is reduced to lower costs, then production expenses decrease, but electrode mechanical strength and adhesion are compromised
Solution Approach 1:
The invention employs composite fluoropolymer systems with optimized composition ratios that maximize binding efficiency per unit mass. The synergistic combination of different fluorinated polymers provides enhanced adhesion strength at lower overall binder content, reducing material costs while maintaining electrode integrity.
Solution Approach 2:
The invention ensures that binder is strategically distributed and activated at critical interfaces (electrode-current collector contact zones) through optimized formulation and processing. This localized quality approach ensures adequate adhesion strength where most needed, allowing reduced overall binder content and lower costs.
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 process ensures cohesive and mechanically strong electrodes with controlled porosity and adhesion, reducing binder content and production costs while maintaining electrochemical performance.
Implementation Method 1
the binder must ensure close contact between the composite electrode and the current collector (adhesion)
Implementation Method 2
The main purpose of using a binder is to form stable networks of the solid components of the electrodes, that is to say the active materials and the conductive agents (cohesion)
Implementation Method 3
consolidated through heat or thermomechanical treatment
Implementation Method 4
consolidating said electrode by a heat treatment and/or thermomechanical 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 secondary batteries comprising at least one such electrode.