Cylindrical Lithium Battery End Venting to Prevent Side Rupture
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Solution Overview
Problem
Large cylindrical lithium secondary batteries face safety issues due to increased heat and gas generation, leading to potential fire or explosion risks, and side rupture can cause flame spread within battery packs.
Innovation Solution
The battery design includes a configuration where the electrode assembly is ejected through one end of the battery can when internal pressure exceeds 21 kgf/cm2, with a distance from the farthest end of the electrode assembly to the opposite end of the battery can being at least 1.25 times the distance between the ends, and features a vent portion that ruptures at specific pressures to release pressure without side rupture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cross-sectional area of the battery is increased to release heat more effectively, then heat dissipation is improved, but the volume increases faster than the cross-sectional area, leading to increased heat generation and explosion risk
Solution Approach 1:
The battery can is divided into two opposite end portions, with vent portions positioned at both ends. This segmentation allows heat and gas to be released from multiple locations simultaneously, improving heat dissipation efficiency without requiring a proportional increase in overall cross-sectional area.
Solution Approach 2:
Instead of relying solely on increasing cross-sectional area for heat release, the invention utilizes the longitudinal dimension by positioning vent portions at both ends of the battery can. This dimensional approach allows effective heat dissipation while maintaining a compact volume.
2Reliability
If vent portions are opened to release internal pressure, then explosion risk is reduced, but side rupture of the battery can occurs, causing flame spread to adjacent batteries
Solution Approach 1:
The harmful function of pressure release is extracted from the side walls and relocated to the end portions of the battery can. The vent portions are specifically positioned at the ends, separating the pressure release function from the side structure, thereby preventing side rupture while maintaining explosion prevention capabilities.
Solution Approach 2:
The internal pressure that could cause side rupture is redirected through controlled vent portions at the ends. The harmful pressure buildup is converted into a controlled ejection of the electrode assembly through the end portions, transforming a potential hazard into a controlled safety mechanism.
3Quantity of substance
If the battery is designed for high capacity with large volume, then energy storage is improved, but the amount of heat and gas generated increases, leading to fire or explosion risks
Solution Approach 1:
The battery can is segmented with vent portions at both end portions, allowing heat and gas to be released from multiple locations. This segmentation enables effective thermal management in high-capacity batteries without compromising energy storage density.
Solution Approach 2:
The vent portions are pre-positioned at the end portions of the battery can before any thermal runaway occurs. This preliminary arrangement ensures that when heat and gas generation becomes critical, the release paths are already in place, preventing fire or explosion while maintaining high capacity.
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 prevents side rupture and local flame occurrence, reducing the risk of fire spread and enhancing safety in battery packs and vehicles by allowing controlled pressure release.
Implementation Method 1
when an internal pressure within the battery can is 21 kgf/cm2 or more, at least a portion of the electrode assembly is ejected through the first end portion of the battery can
Implementation Method 2
features a vent portion that ruptures at specific pressures to release pressure without side rupture
Data Source
AI summary
A lithium secondary battery may include a battery can, an electrode assembly and an electrolyte received in the battery can, and a cap plate to seal the battery can. The battery can includes a first end portion and a second end portion opposite the first end portion. The lithium secondary battery is configured so at least a portion of the electrode assembly is ejected through the first end portion of the battery can when an internal pressure within the battery can is 21 kgf/cm2 or more. After the portion of the electrode assembly is ejected through the first end portion, a distance from an end portion of the electrode assembly located farthest away from the battery can to the second end portion of the battery can is greater than or equal to 1.25 times a distance between the first end portion and the second end portion of the battery can.