Honeycomb Lithium-Ion Battery Cathode Structure Against Separator Cracks
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Solution Overview
Problem
The issue of short-circuiting due to cracks in honeycomb type lithium ion batteries, caused by shrinkage stress of the binder in the cathode paste leading to contact between the anode and cathode, is addressed.
Innovation Solution
A honeycomb type lithium ion battery design with a separator layer that has Li ion permeability, physically isolating the anode and cathode, and a cathode with a higher binder content in surface areas compared to inner areas to reduce shrinkage stress and maintain the cathode's shape, thereby preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is disposed in through holes of an anode and cathode paste is filled, then the battery structure is formed, but shrinkage stress from the binder causes cracks in the separator leading to short-circuiting
Solution Approach 1:
The cathode is designed with non-uniform binder distribution, where the surface area has a higher binder content (5-15 wt%) compared to the inner area (2-10 wt%). This local quality variation allows the surface binder to absorb shrinkage stress during drying, preventing crack propagation to the separator while maintaining structural integrity.
Solution Approach 2:
The binder in the surface area acts as a cushioning layer that absorbs the shrinkage stress generated during the drying process before it can reach and damage the separator. This beforehand cushioning prevents cracks from forming in the first place, ensuring reliable battery operation.
2Shape
If binder content is increased to retain cathode shape, then shape retention is improved, but shrinkage stress on the separator increases causing cracks
Solution Approach 1:
The cathode structure is designed with spatially varying binder content: the surface area contains higher binder concentration for shape retention, while the inner area has lower binder content to minimize shrinkage stress. This local differentiation allows simultaneous achievement of both shape retention and crack prevention.
Solution Approach 2:
The cathode is segmented into two functional zones based on binder content: the surface area with high binder for structural support and shape retention, and the inner area with low binder for reduced shrinkage stress. This segmentation allows each zone to perform its specific function without compromising the other.
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 design effectively suppresses short-circuiting by reducing cracks in the battery, ensuring the cathode and anode remain insulated.
Implementation Method 1
the separator layer has Li ion permeability, physically isolates the anode and the cathode from each other
Data Source
AI summary
Provided is a honeycomb type lithium ion battery capable of suppressing short-circuiting due to cracks. The honeycomb type lithium ion battery has an anode, a cathode, and a separator layer, wherein the anode has a plurality of through holes extending in one direction, the separator layer has partition separator layers and insulating film separator layers, the cathode has inner areas disposed inside the through holes via the partition separator layers, intermediate areas disposed over faces of the inner areas and faces of the insulating film separator layers, and a surface area with which surfaces of the insulating film separator layers and the intermediate areas are covered, and the cathode contains a binder, wherein the proportion of the content of the binder in the surface area is high compared to the proportion of the content of the binder in the inner areas.