Cathode Edge Protection for Lithium-Ion Battery Short Circuit Prevention
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Solution Overview
Problem
Lithium-ion battery cells are prone to internal short circuits due to contaminants getting trapped between the anode and cathode, which can cause latent defects and potentially lead to cell failure or explosion, as the electrodes swell and compress, puncturing the separator.
Innovation Solution
A method of manufacturing lithium-ion battery cells that involves providing a cathode, an anode, and a separator, and covering the edge of the cathode to prevent shorts by calendaring or spraying a protective coating on the cathode edge, or folding the separator to cover the gap, thereby preventing contaminants from causing a short circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the anode is made larger than the cathode to meet battery design requirements, then the battery structure is optimized for performance, but contaminants can be trapped in the pocket between the electrodes causing internal short circuits
Solution Approach 1:
The patent applies preliminary action by forming a protective coating on the cathode edge before assembly, and by designing the separator to extend beyond the cathode edge. This pre-protection prevents contaminants from causing short circuits before they can penetrate the separator during battery operation.
Solution Approach 2:
The patent introduces an intermediary protective coating layer on the cathode edge and extends the separator as an intermediary barrier between the cathode edge and the anode. These intermediary elements prevent direct contact between contaminants and the electrodes, eliminating the harmful effect of contaminant trapping.
2Ease of manufacture
If standard manufacturing processes are used without additional protective measures, then manufacturing simplicity is maintained, but exposed cathode edges create vulnerability to internal short circuits
Solution Approach 1:
The protective coating is applied to the cathode edge during the manufacturing process, and the separator is designed to extend beyond the cathode edge before assembly. This preliminary protection is integrated into the manufacturing flow without requiring complex additional steps, maintaining ease of manufacture while improving reliability.
3Device complexity
If the cathode edge is left exposed during manufacturing, then manufacturing complexity is reduced, but the cathode edge becomes vulnerable to contaminant-induced short circuits during battery operation
Solution Approach 1:
The patent applies local quality by providing protective coating specifically on the cathode edge rather than the entire cathode, and by extending the separator only beyond the cathode edge where needed. This localized protection reduces manufacturing complexity compared to full-surface protection while effectively addressing the edge vulnerability to contaminants.
Data Source
AI summary
Embodiments of methods for preventing internal short circuits in a lithium-ion battery cell. In an embodiment, a method of manufacturing a lithium-ion battery cell may include providing a cathode, providing an anode, providing a separator disposed between the cathode and the anode, and covering an edge of the cathode to prevent a short between the cathode and the anode through the separator. The method may also include winding the cathode, the anode, and the separator into an electrode roll.