Battery Separator Wrapper Prevents Electrode Displacement
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Solution Overview
Problem
Stack-type nonaqueous electrolyte secondary batteries face issues with electrode displacement due to external vibrations or shocks, leading to potential short-circuits and reduced durability, and existing solutions either fail to prevent displacement effectively or compromise battery capacity by requiring thick support structures that reduce electrolyte retention.
Innovation Solution
The battery design incorporates a separator with a fanfold portion between electrodes and a wrapper portion that extends around the periphery of the electrode stack, providing additional support and preventing displacement without significantly reducing battery capacity or electrolyte retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick electrode stack support body is used to fix the electrode stack, then the electrode displacement is prevented, but the battery capacity and electrolyte retention are reduced
Solution Approach 1:
The separator is extended beyond the electrode stack to form a wrapper portion that acts as a flexible restraining structure. This thin film approach prevents electrode displacement without requiring a thick support body, thereby maintaining battery capacity and electrolyte retention.
Solution Approach 2:
The separator performs dual functions: its fanfold portion provides electrical insulation between electrodes during normal operation, while its extended wrapper portion provides mechanical restraint against displacement. This multi-functionality eliminates the need for separate thick support structures.
2Quantity of substance
If no support structure is used, then the battery capacity and electrolyte retention are maintained, but the electrode displacement occurs under vibrations and shocks
Solution Approach 1:
The extended separator acts as a flexible restraining film that provides mechanical support against vibrations and shocks without forming a rigid thick support structure, thus maintaining electrolyte retention while preventing electrode displacement.
3Reliability
If a rigid support structure is used, then the electrode displacement is prevented, but the battery capacity is reduced due to less electrolyte retention space
Solution Approach 1:
The wrapper portion of the separator provides flexible mechanical restraint without forming a rigid structure that would occupy significant space. This maintains maximum electrolyte retention volume and battery capacity while still preventing electrode displacement.
Solution Approach 2:
The separator is designed with changed dimensional parameters - extending beyond the electrode stack boundaries to provide restraint function. This parameter change enables displacement prevention without adding thick support structures that would reduce battery capacity.
Data Source
AI summary
A stack-type nonaqueous electrolyte secondary battery includes an electrode stack. The electrode stack is housed in an exterior body and includes a plurality of positive electrodes, a plurality of negative electrodes, and a separator. The positive electrodes and the negative electrodes are alternately arranged. The separator includes a fanfold portion including a plurality of intervening elements interposed between the positive electrodes and the negative electrodes. The separator includes a wrapper portion at a portion continuous with the fanfold portion. The wrapper portion extends out of the electrode stack and is disposed to cover at least part of a periphery of the electrode stack.