Battery End Cap Structure for Cylindrical Cell Shorting Protection
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Solution Overview
Problem
Conventional cylindrical lithium-ion cells are vulnerable to accidental shorting due to the thin polymer wrapper being easily damaged during use, which can lead to cell failure, bodily harm, and property damage.
Innovation Solution
The use of mechanically tough, insulative polymer battery endcaps that securely fit over the terminals of lithium-ion cells to create a barrier between the positive and negative terminals, preventing shorting through a ring-shaped or cylindrical design with a central hole for the positive terminal and secure attachment via a snap fit or adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin polymer wrapper is used to cover the cell, then the cell is protected against shorting, but the wrapper can easily be damaged during use
Solution Approach 1:
The protection system is divided into two parts: the original thin polymer wrapper and an additional end cap component. The end cap segments the protection function by specifically covering the vulnerable terminal area, while the wrapper provides general coverage. This segmentation allows each component to be optimized independently - the wrapper remains thin for flexibility while the end cap provides enhanced mechanical protection.
Solution Approach 2:
The solution combines two different protective elements: the existing polymer wrapper and a new end cap made of mechanically tough material. This composite approach integrates the electrical insulation properties of the polymer with the mechanical strength of the end cap material, creating a multi-layered protection system that addresses both reliability and strength requirements.
2Reliability
If a molded silicone case is used to surround the cell, then the terminals are insulated from one another, but the case must be removed while the cell is in use
Solution Approach 1:
Instead of providing uniform protection around the entire cell, the end cap applies protection locally only where it is most needed - at the terminal end of the cell. This local quality approach focuses the protective function on the vulnerable area where terminals are exposed, eliminating the need for a complete surrounding case while maintaining continuous protection during device operation.
Solution Approach 2:
The end cap is pre-installed on the cell before the cell is placed into the electronic device. This preliminary action ensures that protection is already in place and continuous throughout the device's operation, eliminating the need to install or remove protective cases during use. The protection is established in advance and remains in effect continuously.
Data Source
AI summary
Devices for insulating the electrical terminals of cylindrical batteries, such as lithium-ion cells, to prevent the occurrence of shorting. One configuration is a device or apparatus which covers one or more terminals of the cell, thereby providing an insulative barrier, while still allowing the cell to be used. Another configuration is a cell covering partially covering the topmost portions of the negatively charged exterior cell case, closest to the positive terminal of the cell, and attaching the covering via a circumferential appendage which locks onto the cell. In another configuration the cell covering extends axially down the side of the cell case to cover part of, or the entirety of, the side of the negatively charged case.