Secondary Battery Insulating Member Prevents Electrical Shorts
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Solution Overview
Problem
Lithium ion secondary batteries face electrical shorts between the cylindrical can and cap assembly due to melting of the insulating gasket, which can lead to electrolyte leakage and moisture infiltration.
Innovation Solution
Incorporating an insulating member with a higher melting temperature than the gasket, located between the cylindrical can and cap assembly, to maintain electrical insulation even when the gasket melts, thereby preventing direct electrical contact and ensuring the sealing capacity is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating gasket is used between the cylindrical can and cap assembly, then electrical insulation is provided, but the gasket melts at elevated temperatures causing electrical shorts
Solution Approach 1:
The insulating member is formed by composite materials including heat-resistant resin (such as polyimide, polyether sulfone, or polyphenylene sulfide) combined with inorganic fillers (such as aluminum oxide, aluminum hydroxide, or magnesium hydroxide). This composite structure provides both electrical insulation and high-temperature resistance, preventing melting at elevated temperatures while maintaining insulating properties.
Solution Approach 2:
The invention changes the thermal parameters of the insulating material by selecting resins with glass transition temperatures of 200°C or higher and incorporating inorganic fillers that raise the decomposition temperature. This parameter change enables the insulating member to maintain its structural integrity and insulating function at temperatures where conventional gaskets would melt.
2Reliability
If conventional insulating materials are used, then electrical insulation is achieved, but insulation fails at high temperatures leading to safety issues
Solution Approach 1:
The insulating member is constructed from composite materials including heat-resistant resin (polyimide, polyether sulfone, or polyphenylene sulfide) and inorganic fillers (aluminum oxide, aluminum hydroxide, or magnesium hydroxide) in a weight ratio of 20:80 to 80:20. This composite provides superior high-temperature resistance compared to conventional insulating materials, preventing electrical shorts and electrolyte leakage even when exposed to elevated temperatures during battery operation or abuse conditions.
Solution Approach 2:
The insulating member is pre-installed at the sealing portion between the cylindrical can and cap assembly before battery assembly. It provides beforehand protection against electrical shorts and electrolyte leakage by maintaining its insulating and sealing functions even under anticipated thermal stress, preventing harmful effects before they can occur during battery operation or failure scenarios.
Data Source
AI summary
Various embodiments of the present invention relate to a secondary battery, wherein a technical problem to be solved is to provide a secondary battery capable of maintaining an electrical insulating state between a case (can) and a cap assembly even after a gasket is melted due to short-circuiting and heat generation. To this end, the present invention provides a secondary battery comprising: a cylindrical can; an electrode assembly received, along with an electrolyte, in the cylindrical can; a cap assembly for sealing the cylindrical can; and a gasket interposed between the cylindrical can and the cap assembly, wherein the gasket further includes an insulating member having a melting temperature higher than a melting temperature of the gasket.