Dry-Process Battery Electrode with Uniform PTFE Binder Distribution
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Solution Overview
Problem
The existing methods for producing electrodes for non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, face issues with the uneven distribution of binder and poor in-plane dispersibility of PTFE, leading to decreased tensile strength due to aggregation and adhesion of conductive agents to PTFE rather than the active material.
Innovation Solution
The electrode is manufactured using a dry process where the active material, PTFE, and conductive agents are mixed and then stretched through rollers to form a sheet, ensuring a uniform distribution of PTFE with a standard deviation of less than 6% in adjacent sections, and laminated onto a core, maintaining a specific content ratio across the electrode thickness to enhance tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If PTFE content rate is increased and large shearing force is applied for long time to fibrillate PTFE, then PTFE dispersibility in thickness direction is improved, but conductive agent adheres to PTFE instead of active material and PTFE aggregates, decreasing in-plane dispersibility and tensile strength
Solution Approach 1:
The patent applies different treatment conditions to PTFE based on its required function: minimal fibrillation for conductive agent adhesion (local quality 1) versus controlled dispersion for structural integrity (local quality 2). By optimizing PTFE particle size distribution and controlling shearing force application, the patent achieves uniform thickness distribution without excessive fibrillation that would cause aggregation and conductive agent misadhesion, thereby maintaining tensile strength while improving compositional stability.
2Ease of manufacture
If wet method is used to apply electrode mixture slurry, then electrode mixture can be formed on core, but binder migrates during drying causing uneven distribution in thickness direction
Solution Approach 1:
The patent replaces the wet chemical method (slurry application followed by drying) with a mechanical mixing and lamination approach. The electrode mixture is prepared as a dry powder mixture with controlled PTFE content and particle size, then laminated onto the core using mechanical pressure. This substitution eliminates the drying process that causes binder migration, achieving uniform binder distribution while maintaining ease of manufacture through a simplified process without drying steps.
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 improves the tensile strength of the electrode by ensuring uniform PTFE distribution and adhesion to the active material, preventing aggregation and maintaining battery performance.
Implementation Method 1
measuring a surface of the electrode mixture using energy-dispersive X-ray analysis
Implementation Method 2
kneading and simultaneously stretching the electrode mixture particles by passing the electrode mixture particles through a gap between rollers
Data Source
AI summary
An electrode according to one embodiment of the present disclosure comprises: a core material; and an electrode combined material that is layered onto surfaces of the core material. The electrode combined material comprises an active substance and PTFE. In an image illustrating a composition distribution obtained upon measuring a surface of the electrode combined material using energy dispersion-type X-ray analysis, the standard deviation of the area ratio of PTFE in 30 adjacent sections having a size of 150 μm×133 μm is 6% or less. When the electrode combined material is divided into three equal parts in the thickness direction to create, from the core material side, a first region, a second region, and a third region, the content (a) of PTFE in the first region, the content (b) of PTFE in the second region, and the content (c) of PTFE in the third region satisfy (c−a)/(a+b+c)≤±10%.