Battery Current Collector Insulating Layer for Short-Circuit Prevention
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Solution Overview
Problem
Existing electrochemical devices, particularly lithium ion batteries, face safety issues due to potential short-circuits caused by external forces, leading to explosions, as coatings with high resistivity on current collectors lose adhesion in electrolytic solutions, failing to provide effective protection.
Innovation Solution
A specific insulating layer is applied to uncoated regions of the cathode current collector, ensuring adhesion greater than 0.5 N/m, with controlled porosity and composition, to prevent dangerous short-circuits during nail penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating with high resistivity is applied to the current collector to prevent short-circuits, then electrical insulation is improved, but adhesion to the current collector deteriorates in electrolytic solutions
Solution Approach 1:
The patent applies a composite insulating layer comprising multiple materials including polyvinylidene fluoride, carboxymethyl cellulose, and styrene-butadiene rubber. This composite structure provides both high electrical resistivity for insulation and sufficient adhesion to the current collector, resolving the contradiction between insulation performance and bonding strength.
Solution Approach 2:
The patent optimizes the thickness of the insulating layer to a specific range (5-20 micrometers) and controls the weight ratio of components in the coating mixture. By adjusting these parameters, the coating achieves optimal balance between electrical insulation capability and mechanical adhesion to the current collector surface.
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 insulating layer effectively enhances the mechanical safety of lithium ion batteries by maintaining adhesion and preventing short-circuits, improving the nail penetration test pass rate and overall safety performance.
Implementation Method 1
the adhesion between the insulating layer and the first current collector is not less than about 0.5 N/m
Implementation Method 2
coatings with high resistivity on current collectors
Data Source
AI summary
A cell, formed by winding or stacking a first electrode and a second electrode which are arranged at an interval, and a separator is disposed between the first electrode and the second electrode. The first electrode includes a first current collector, and the first current collector includes a coated region coated with a first active material and an uncoated region without the first active material; the uncoated region is at least partially provided with an insulating layer. The adhesion between the insulating layer and the first current collector is not less than about 0.5 N/m.