Battery Cell Weak-Seal Venting for Thermal Gas Release
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Solution Overview
Problem
Current battery cells face safety issues due to declining thermal stability as voltage and energy density increase, leading to potential hazards during consumer use.
Innovation Solution
A battery cell design featuring an electrode assembly and a packaging bag with a sealing zone that includes a weak zone, where the packaging tension reduces in a predetermined temperature range to release gas outside the cell, thereby reducing heat accumulation and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If voltage and energy density of battery cells are increased, then energy storage capacity is improved, but thermal stability deteriorates leading to safety issues
Solution Approach 1:
The packaging bag is divided into different functional zones: a sealing zone with a weak zone for pressure release and a non-sealing zone for maintaining structural integrity. This segmentation allows the battery cell to maintain high energy density while incorporating a safety mechanism that releases pressure during thermal events, thereby resolving the contradiction between energy density and thermal stability.
Solution Approach 2:
The weak zone acts as an intermediary element between the internal electrode assembly and the external environment. It provides a controlled pressure release path that activates during thermal events, mediating between the high energy storage capability and the thermal stability requirement by preventing uncontrolled pressure buildup.
2Reliability
If packaging tension is reduced in weak zone to release gas, then safety is improved, but sealing performance deteriorates
Solution Approach 1:
Different zones of the packaging bag are assigned different quality characteristics: the sealing zone has high sealing strength to maintain integrity, while the weak zone within it has reduced packaging tension to enable pressure release. This local differentiation allows the packaging bag to simultaneously achieve both sealing performance and safety through controlled pressure release.
Solution Approach 2:
The packaging tension parameter is specifically adjusted in the weak zone to be lower than in other regions, creating a temperature-dependent behavior where the zone remains sealed under normal conditions but releases pressure when thermal events occur. This parameter change enables the packaging bag to adapt its sealing characteristics based on operational conditions.
3Use of energy by moving object
If packaging bag is made more robust to contain high energy, then energy density is maintained, but thermal runaway risk increases
Solution Approach 1:
The weak zone is designed in advance as a pressure relief mechanism that activates before thermal runaway can occur. By providing a predetermined pressure release path, the packaging bag cushions against the buildup of internal pressure during thermal events, preventing catastrophic failure while maintaining the structural integrity needed for high energy storage.
Solution Approach 2:
The potential harm of pressure buildup during thermal events is converted into a beneficial safety mechanism through the weak zone design. The controlled failure of this specific zone provides a pressure release path that prevents uncontrolled thermal runaway, transforming what would be a harmful effect into a protective feature that enables high energy storage.
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 significantly improves the safety performance of battery cells by releasing heated gas and reducing heat accumulation, thus alleviating deformation and preventing safety issues such as short circuits and fires.
Implementation Method 1
the weak zone is formed through thermal fusion of the second sealing adhesive and the packaging bag
Implementation Method 2
in a predetermined temperature range, a packaging tension between the weak zone and the packaging bag reduces to release gas inside the battery cell to the outside of the battery cell
Data Source
AI summary
A battery cell includes an electrode assembly and a packaging bag, where the electrode assembly includes a tab, the packaging bag is configured to accommodate the electrode assembly, a sealing zone is formed on a periphery of the packaging bag, one end of the tab is electrically connected to a body of the electrode assembly, and an other end of the tab protrudes out of the sealing zone; the sealing zone is provided with a weak zone, and in a predetermined temperature range, a packaging tension of the weak zone in the packaging bag reduces to release gas inside the battery cell to the outside of the battery cell.