Secondary Battery Insulation Layer Preventing Electrical Shorts
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Solution Overview
Problem
Lithium ion secondary batteries face issues with unintended electric shorts between the cylindrical can and cap assembly, which can lead to fabrication complexities and module structure complications.
Innovation Solution
A secondary battery design incorporating an insulation layer on the cap assembly, including a polyimide film or hot melt block, interposed between the lead tabs and the cap assembly, prevents electrical shorts and simplifies the module structure by connecting the lead tabs to the cylindrical can and cap assembly in a way that reduces short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead tabs are connected to the cylindrical can and cap assembly without insulation, then electrical connection is achieved, but unintended electric shorts occur between the cylindrical can and cap assembly
Solution Approach 1:
An insulation layer is introduced as an intermediary component between the lead tabs and the cap assembly. This insulation layer prevents direct electrical contact between the cylindrical can and cap assembly while still allowing the lead tabs to establish electrical connections, thereby eliminating the harmful electric shorts without compromising electrical connection reliability.
Solution Approach 2:
The cap assembly is divided into functionally distinct regions: an insulated portion that prevents electric shorts, and a conductive portion that maintains electrical connection. This segmentation allows different parts of the cap assembly to serve different purposes - one part prevents harmful electrical contact while another part facilitates necessary electrical connections.
2Reliability
If insulation structures are added to prevent electric shorts, then reliability improves, but device complexity increases
Solution Approach 1:
The cap assembly is designed to serve multiple functions simultaneously: it provides structural support, enables electrical connection through its conductive portion, and prevents electric shorts through its insulated portion. By making the cap assembly multi-functional, additional components are avoided, and device complexity is minimized while still achieving reliable short prevention.
Solution Approach 2:
The insulation function is merged with the cap assembly structure itself rather than being implemented as a separate standalone component. The insulation layer is integrated onto the cap assembly, combining the protective insulation function with the existing cap structure, thereby preventing electric shorts without significantly increasing overall device complexity.
Data Source
AI summary
A secondary battery includes a cylindrical can; an electrode assembly accommodated in the cylindrical can with an electrolyte; a cap assembly sealing the cylindrical can, a top-end height of the cap assembly being equal to or less than a top-end height of the cylindrical can; and an insulation layer on a surface of the cap assembly that is exposed to the outside of the cylindrical can.