Battery End Cover Assembly With Melt-Resistant Terminal Insulation
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Solution Overview
Problem
Lithium battery cells are prone to thermal runaway due to internal short circuits, leading to safety incidents such as fires and explosions, as the electrode terminals can conductively connect during thermal runaway, causing a short circuit between polarities.
Innovation Solution
An end cover assembly with a sealing element that includes a body and a first insulating element with a higher melting point, which insulates the electrode terminal from the cover plate by deforming and exposing the insulating element during thermal runaway, preventing conductive contact and maintaining insulation between the terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sealing element is made of a single material with low melting point, then it can deform easily to seal the electrode lead-out hole, but it will lose insulating properties when melted during thermal runaway
Solution Approach 1:
The sealing element is constructed as a composite structure with a body made of low-melting-point material (e.g., wax, paraffin) and an insulating element made of high-melting-point material (e.g., ceramic, glass) embedded within it. This composite design allows the sealing element to deform and seal effectively at normal temperatures while maintaining insulating properties during thermal runaway, as the high-melting-point insulating element remains intact even when the low-melting-point body softens.
2Reliability
If the insulating element protrudes significantly from the body, then it can provide adequate insulation after melting, but it increases the outline dimensions of the sealing element
Solution Approach 1:
The insulating element is embedded within or nested inside the body of the sealing element, rather than protruding significantly from it. This nested configuration allows the insulating element to be positioned strategically within the sealing structure, providing adequate insulation functionality while minimizing the overall outline dimensions of the sealing element and maintaining a compact design.
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 solution effectively insulates the electrode terminals during thermal runaway, preventing short circuits and enhancing the safety performance of the battery cell by ensuring the terminals remain isolated, thus reducing the risk of safety incidents.
Implementation Method 1
the first insulating element is connected to the body and has a higher melting point than the body; and the first insulating element is configured to insulate the electrode terminal from the cover plate after the body is melted
Data Source
AI summary
An end cover assembly may include: a cover plate provided with an electrode lead-out hole; an electrode terminal located on one side of the cover plate in a thickness direction and covering the electrode lead-out hole; and a sealing element disposed between the electrode terminal and the cover plate so as to seal the electrode lead-out hole along a circumference of the electrode lead-out hole. The sealing element may include a body and a first insulating element. The first insulating element may be connected to the body and have a higher melting point than the body. The first insulating element may be configured to insulate the electrode terminal from the cover plate after the body is melted, so as to keep electrode terminals of two polarities insulated from each other at thermal runaway of a battery cell.