Rechargeable Battery Safety Device for Swelling Gas Release
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Solution Overview
Problem
Rechargeable lithium batteries face safety issues due to swelling caused by excessive internal gas pressure from conditions like overcharge, over-discharge, internal shorts, and overheating, which can lead to pouch material failure.
Innovation Solution
Incorporating a safety device within the pouch that includes a bonding member, a fin member with a sharp tip, and a linking member to puncture the pouch and release internal gas when swelling occurs, utilizing a multi-layered structure with thermal bonding and materials like stainless steel and polypropylene to manage swelling and gas release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety device is added to puncture the pouch and release gas, then safety is improved, but device complexity increases
Solution Approach 1:
The safety device is divided into three separate components: a bonding member that attaches to the pouch, a linking member that connects the bonding member to the fin member, and a fin member with a sharp tip that punctures the pouch. This segmentation allows each component to perform its specific function while keeping the overall structure manageable and manufacturable.
Solution Approach 2:
The linking member acts as an intermediary between the bonding member and the fin member. It transfers the movement force from the bonding member (which moves when the pouch swells) to the fin member (which punctures the pouch). This intermediary structure enables the safety mechanism to function without requiring direct connection between the bonding and fin members.
2Strength
If the pouch is made stronger to prevent rupture, then strength is improved, but the ability to release gas controllably worsens
Solution Approach 1:
The fin member is pre-positioned within the pouch with its sharp tip facing an inner side of the pouch, but spaced apart from it. The linking member connects the fin member to the bonding member, which is already bonded to the pouch. When swelling occurs, the pre-arranged structure automatically activates to puncture the pouch at a controlled location, preventing uncontrolled rupture while maintaining pouch strength during normal operation.
Solution Approach 2:
The safety device components are pre-assembled and positioned within the pouch before sealing. The fin member is oriented with its tip facing a specific inner side of the pouch, and the linking member is pre-connected to the bonding member. This preliminary arrangement ensures that when swelling occurs, the gas release happens at a predetermined location in a controlled manner.
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 prevents pouch rupture by allowing controlled gas release during swelling, enhancing the safety and reliability of rechargeable batteries by mitigating the risks associated with excessive internal pressure.
Implementation Method 1
a bonding member bonded to one of the inner sides of the pouch
Data Source
AI summary
A rechargeable battery improving safety by discharging a gas when swelling occurs. The rechargeable battery includes an electrode assembly having a first electrode plate and a second electrode plate arranged at opposite sides of a separator, a pouch to accommodate the electrode assembly, the pouch having a plurality of inner sides, a first tab connected to the first electrode plate and a second tab connected to the second electrode plate, the first tab and the second tab extending to an outside of the pouch and a safety device arranged within the pouch and including a bonding member bonded to one of the inner sides of the pouch, a fin member including a tip facing and being spaced-apart from one of the inner sides of the pouch, and a linking member connecting the fin member to the bonding member.