Prismatic Battery Cell Venting With Melt-Separating Lid Joints
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Solution Overview
Problem
Existing prismatic battery cells face challenges during thermal runaway events, where pressure-based vents may not be sufficient to release all hot gases and electrode particles, leading to local pressure buildup and potential breach of battery cell walls.
Innovation Solution
The battery cell enclosure features a can body with a lid and bottom portion joined using braze filler materials with specific melting temperatures, allowing for controlled venting by separating the lid or bottom from the can body at predetermined temperatures, thereby creating larger vent areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If pressure-based vents are used in battery cells, then venting function is provided, but vent area is insufficient to release all hot gases and electrode particles
Solution Approach 1:
The enclosure is divided into a can body and a removable end cap assembly. The end cap can be separated from the can body to create a large vent area, allowing comprehensive release of hot gases and electrode particles during thermal runaway events.
Solution Approach 2:
The end cap is designed to be removable from the can body, transforming the static enclosure into a dynamic structure that can open up during thermal runaway to provide sufficient venting area for safety.
2Strength
If lid and bottom are permanently attached to can body, then structural integrity is maintained, but venting capability is limited
Solution Approach 1:
The enclosure is segmented into a can body and a separate end cap assembly that includes the lid. This segmentation allows the end cap to be removed during thermal runaway to create a large vent area, while maintaining structural integrity during normal operation.
Solution Approach 2:
The enclosure transitions from a closed, structurally intact state to an open, venting state by removing the end cap. This dynamic capability allows the structure to adapt between maintaining integrity and providing venting area as needed.
3Temperature
If brazed filler material with low melting temperature is used, then controlled venting at lower temperature is achieved, but risk of premature venting increases
Solution Approach 1:
The melting temperature of the brazed filler material is carefully selected and controlled to ensure it activates at an appropriate temperature during thermal runaway, balancing controlled venting with prevention of premature venting that could compromise battery safety.
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 solution effectively releases hot gases and electrode particles during thermal runaway, preventing cell breach and reducing the risk of thermal runaway propagation in the battery pack by providing larger vent areas and controlled temperature-based venting.
Implementation Method 1
a lid portion joined to the first opening of the can body by a first brazed filler material that is arranged between the lid portion and the can body and that has a first melting temperature
Data Source
AI summary
A battery cell comprises a battery cell stack including A anode electrodes; C cathode electrodes; and S separators, where A, C, and S are integers greater than one. An enclosure configured to house the battery cell stack includes a can body defining a first opening and a second opening at opposite ends of the can body; a lid portion joined to the first opening of the can body by a first brazed filler material that is arranged between the lid portion and the can body and that has a first melting temperature; and a bottom portion joined to the second opening of the can body.