Secondary Battery Insulation for Short Circuit Safety
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Solution Overview
Problem
Secondary batteries connected in parallel face reliability issues due to short circuits, where the current interrupting mechanism or fuse part activation can lead to high temperatures, causing insulating members to melt and potentially forming a closed circuit, resulting in abnormal events in connected batteries.
Innovation Solution
Incorporating a second insulating member with higher thermal resistance between the external conductive member and the sealing plate, which maintains a distance and prevents contact between the terminal and the sealing plate even at high temperatures, thus preventing the formation of a closed circuit and reducing the risk of abnormal events in other batteries connected in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current interrupting mechanism or fuse part is disposed in the conduction path to improve reliability, then the battery can terminate current flow during short circuit, but the insulating member may melt at high temperature and form a closed circuit causing abnormal events
Solution Approach 1:
A second insulating member with higher thermal resistance is introduced as an intermediary between the external conductive member and the sealing plate. This mediator prevents direct thermal contact and electrical contact, blocking the harmful effect of high temperature from reaching the first insulating member while maintaining the current interrupting function.
Solution Approach 2:
The second insulating member is disposed beforehand to cushion against the potential harmful effect of high temperature. By placing this thermal buffer in advance, the system prevents the first insulating member from melting even when high temperature occurs during short circuit, thus avoiding the formation of a closed circuit.
2Reliability
If the first insulating member is made of resin to provide electrical insulation, then the terminal is electrically insulated from the sealing plate, but the resin melts at high temperature causing terminal contact with sealing plate
Solution Approach 1:
The system uses a composite insulation structure combining two different insulating members with different thermal resistance properties. The first insulating member (resin) provides basic electrical insulation, while the second insulating member with higher thermal resistance provides thermal stability, creating a composite solution that addresses both electrical and thermal requirements.
Solution Approach 2:
Different regions of the insulation system are assigned different properties: the first insulating member uses resin material optimized for electrical insulation at normal temperatures, while the second insulating member uses material with higher thermal resistance optimized for high-temperature stability. Each part has localized quality suited to its specific function.
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
This design enhances the reliability of secondary batteries and battery packs by preventing the re-establishment of current flow in case of a short circuit, thereby minimizing the occurrence of abnormal events in connected batteries.
Implementation Method 1
A second insulating member having higher thermal resistance than the first insulating member is disposed between the external conductive member and the sealing plate
Data Source
AI summary
Provided are a secondary battery and a battery pack including the secondary battery. A sealing plate has a positive electrode terminal attachment hole. A positive electrode terminal penetrates the positive electrode terminal attachment hole. An external conductive member is connected to a portion of the positive electrode terminal located on the battery outer side with respect to the sealing plate. The conduction path between a positive electrode plate and the positive electrode terminal is provided with a current interrupting mechanism. A first insulating member made of resin is disposed between the sealing plate and the positive electrode terminal. A second insulating member having higher thermal resistance than the first insulating member is disposed between the external conductive member and the sealing plate.