Bottom-Vented Secondary Battery Gap Structure for Safe Degassing
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Solution Overview
Problem
Bottom-vented secondary batteries with vents installed at the bottom of the case can suffer from case destruction during events or thermal runaway due to increased degassing paths, compromising safety and performance.
Innovation Solution
Incorporating a gap-maintaining part within the secondary battery to maintain a consistent gap of at least 0.7 mm between the electrode assembly and the vent, ensuring a reliable gas discharge passage and improving degassing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vent is installed at the bottom of the case in a bottom-vented secondary battery, then the degassing path is increased, but the case may be destroyed during events or thermal runaway
Solution Approach 1:
The invention divides the case into multiple segments: the case body, a separate vent cap assembly, and a gap-maintaining part. This segmentation allows the vent function to be isolated from the main case structure, enabling gas discharge without compromising the overall case integrity during thermal runaway events.
Solution Approach 2:
The gap-maintaining part acts as an intermediary element between the electrode assembly and the vent cap. It maintains a specific gap (0.7mm or more) to ensure proper gas flow path while protecting the case structure from direct exposure to excessive pressure and heat during thermal events.
2Reliability
If the gap between the electrode assembly and vent is increased to ensure gas discharge passage, then degassing performance is improved, but the device complexity increases
Solution Approach 1:
The gap-maintaining part is integrated with the vent cap assembly rather than being a separate component. This merging approach ensures the required gap (0.7mm or more) is maintained while minimizing the number of discrete parts, thus improving gas discharge capability without significantly increasing device complexity.
3Reliability
If a gap-maintaining part is added to maintain the gap between electrode assembly and vent, then gas discharge passage is ensured, but the manufacturing process becomes more complex
Solution Approach 1:
The gap-maintaining part is pre-formed as an integrated feature of the vent cap assembly during the molding process. This preliminary action ensures the correct gap (0.7mm or more) is built-in from manufacturing, eliminating the need for additional assembly steps or adjustments, thereby ensuring reliable degassing performance while maintaining manufacturing simplicity.
Data Source
AI summary
Disclosed herein is a secondary battery including a vent through which gas may be discharged in the event of an internal event, and a method of manufacturing the same, and which provides a structure for ensuring a gas passage within the bottom-vented secondary battery to avoid destruction of a case if an event occurs or during thermal runaway due to an increase in degassing path in the secondary battery. To this end, there are provided a secondary battery, which includes a case, an electrode assembly in the case, a first cap plate coupled to the case, a vent opposite the first cap plate, and a gap-maintaining part for maintaining a gap between the electrode assembly and the vent, a method of manufacturing the same, and a vehicle including the secondary battery.