Battery Cell End Cover Sealing for Electrolyte Injection Holes
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Solution Overview
Problem
Lithium-ion batteries face issues with electrolyte leakage and impurity ingress due to poor sealing, which reduces their operational life and poses environmental risks.
Innovation Solution
An end cover assembly with a nail body and fixing portion design that includes an annular accommodating portion and sealing members, providing balanced force distribution and increased contact area to enhance sealing performance, along with a locking mechanism for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple through hole design is used for electrolyte injection, then the manufacturing process is simple, but the sealing performance is poor and electrolyte leakage occurs
Solution Approach 1:
The end cover plate is segmented into multiple functional regions: the through hole for electrolyte injection, the fixing portion with inner and outer walls for structural support, and the sealing member positioned between them. This segmentation allows each component to perform its specific function optimally while maintaining overall sealing performance
Solution Approach 2:
A sealing member is introduced as an intermediary component between the nail body and the fixing portion. This sealing member fills the gap and prevents electrolyte leakage, resolving the contradiction between simple manufacturing and reliable sealing by adding a dedicated sealing element
2Reliability
If the nail body is tightly engaged with the fixing portion to improve sealing, then sealing performance improves, but assembly difficulty increases
Solution Approach 1:
The sealing member is made of flexible material that can deform during the assembly process. This flexibility allows the sealing member to be easily inserted and engaged with the fixing portion, reducing assembly difficulty while maintaining tight engagement for reliable sealing performance
Solution Approach 2:
The sealing member is designed to transition from a loose state during assembly to a tightly engaged state during operation. This dynamic behavior allows easy assembly followed by reliable sealing, resolving the contradiction between assembly ease and sealing performance
3Reliability
If the fixing portion is enlarged to increase contact area, then sealing performance improves, but the device complexity increases
Solution Approach 1:
The fixing portion is designed with local quality variations: the inner wall and outer wall are positioned at specific locations to provide optimal contact areas. This localized design increases sealing contact area without requiring a significant enlargement of the entire fixing portion, thereby maintaining structural simplicity
Data Source
AI summary
The present application provides an end cover assembly, a battery cell, a battery pack, apparatus and a liquid injection method. The end cover assembly includes an end cover plate, including a through hole for injecting electrolyte and a fixing portion arranged around the through hole; a nail body, including an accommodating portion for receiving the fixing portion. The accommodating portion is in a shape of annular and includes two inner walls arranged to be spaced apart from each other in a radial direction of the accommodating portion, and an inner wall and an outer wall of the fixing portion are respectively pressed against and engaged with the two inner walls of the accommodating portion to seal the through hole.