Battery Electrode Coating Layer for Heat-Resistant Ion Permeation
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Solution Overview
Problem
Conventional separation membranes used in lithium secondary batteries suffer from heat resistance issues, leading to deterioration at high temperatures, and there is a need for improved ion permeability and high temperature stability to enhance energy density.
Innovation Solution
A coating layer comprising rod-shaped inorganic particles and spherical organic particles is applied directly to the electrode active material layer, with a specific ratio of major axis to diameter, enhancing air permeability and heat resistance, thereby replacing the conventional separation membrane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin microporous membrane is used as a separation membrane substrate, then ion permeability is improved, but heat resistance deteriorates (membrane melts at high temperature)
Solution Approach 1:
The invention uses a composite coating layer comprising both inorganic particles (such as alumina, silica, or boehmite) and organic binder resin on the separation membrane. This composite structure combines the heat resistance of inorganic materials with the ion permeability of the polyolefin substrate, resolving the contradiction between heat resistance and ion permeability
Solution Approach 2:
The invention specifies particular parameters for the coating layer including particle size distribution (0.1-10 μm), weight ratio of inorganic particles to binder resin (95:5 to 50:50), and coating thickness (1-20 μm). These parameter optimizations ensure the coating provides sufficient heat resistance while maintaining ion permeability through controlled porosity
2Temperature
If the separation membrane thickness is increased to improve high temperature stability, then heat resistance is improved, but energy density deteriorates
Solution Approach 1:
The invention employs a porous coating layer with controlled porosity (30-70%) that allows ion transport while providing thermal stability. The porous structure achieves high temperature stability without requiring increased membrane thickness, thus maintaining energy density
Solution Approach 2:
Instead of increasing thickness in one dimension to improve heat resistance, the invention adds a functional coating layer on the surface, transitioning the solution to another dimension (surface modification rather than bulk thickening). This maintains the membrane's thin profile and high energy density while achieving thermal stability
3Temperature
If a coating layer with inorganic particles is applied to improve heat resistance, then high temperature stability is improved, but ion permeability may deteriorate
Solution Approach 1:
The invention creates local quality variations in the coating layer by using a bimodal particle size distribution. Larger particles (3-10 μm) provide heat resistance framework while smaller particles (0.1-1 μm) fill gaps and maintain porosity for ion transport. This local differentiation ensures both heat resistance and ion permeability
Solution Approach 2:
The coating layer is designed with controlled porosity (30-70%) through selective particle packing and binder resin distribution. The porous structure allows electrolyte penetration and ion transport while the inorganic particle framework maintains structural integrity at high temperatures
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 coating layer improves energy density and operational stability of secondary batteries by maintaining high temperature stability and reducing thickness, while maintaining excellent ion permeability.
Implementation Method 1
a separation membrane having excellent ion permeability and high temperature stability
Data Source
AI summary
An electrode for a secondary battery according to exemplary embodiments includes an electrode current collector; an electrode active material layer formed on the electrode current collector; and a coating layer formed on the electrode active material layer and including rod-shaped inorganic particles and spherical organic particles, wherein a ratio of a length of major axis of the rod-shaped inorganic particle to a length of diameter of the spherical organic particle may be 3 to 5.