Leaf Spring Battery Connector for Venting and Cell Length Variation
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Solution Overview
Problem
Existing connectors for Lithium-Ion battery cells fail to address issues such as restricted outgassing during thermal runaway, excessive heat generation due to rough contact surfaces, and incompatibility with both protected and unprotected cell lengths.
Innovation Solution
A leaf spring connector made of conductive sheet metal, designed with material removals to allow unobstructed outgassing, a header lip fold for maintaining ventilation, and a maximum spring travel distance to accommodate varying cell lengths, providing a low-resistance electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a connector is designed with a rigid structure to ensure stable electrical connection, then electrical contact reliability is improved, but the connector blocks the outgassing path during thermal runaway
Solution Approach 1:
The connector employs a flexible leaf spring structure instead of a rigid connection, allowing the spring to deform and accommodate the expansion of the battery cell during thermal runaway while maintaining electrical contact. The spring's flexibility enables it to yield under pressure, preventing blockage of the outgassing path while preserving stable electrical connection during normal operation.
Solution Approach 2:
The connector is constructed as a thin, flexible leaf spring that can bend and deform to accommodate battery expansion. This flexible structure allows the connector to adapt to changing battery dimensions during thermal runaway events, maintaining electrical contact without obstructing the venting path for safety gas release.
2Adaptability or versatility
If the spring travel distance is increased to accommodate protected cells, then compatibility with both protected and unprotected cells is improved, but the connector structure becomes more complex
Solution Approach 1:
The leaf spring connector is designed with sufficient travel distance to accommodate both protected and unprotected battery cells, making it a universal connector that works with multiple cell types. The spring's length and flexibility are optimized to provide the necessary range of motion for different cell configurations without requiring separate connector designs.
Solution Approach 2:
The connector design adjusts key parameters such as spring length, thickness, and material properties to achieve the required travel distance. By modifying these physical parameters, the connector can accommodate varying cell lengths while maintaining a relatively simple single-piece structure that avoids excessive complexity.
3Reliability
If the connector material is made softer to accommodate rough cell surfaces, then electrical contact quality is improved, but the connector strength decreases
Solution Approach 1:
The connector employs different material properties at different locations: the contact surface is made softer and more compliant to accommodate rough cell surfaces and ensure good electrical contact, while the bulk of the spring maintains higher strength to provide sufficient mechanical support and spring force. This gradient in material properties allows simultaneous optimization of contact quality and structural strength.
Solution Approach 2:
The connector utilizes composite construction or surface treatments where a softer contact layer or coating is applied to the leaf spring. This allows the contact surface to be compliant and adaptive to rough cell surfaces, while the underlying structure retains the strength and rigidity needed for mechanical support and spring function.
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 connector enables safe and efficient outgassing during thermal runaway, reduces heat generation due to improved contact surfaces, and ensures compatibility with both protected and unprotected Lithium-Ion cells.
Implementation Method 1
A non-welded, leaf spring battery cell connector is made from a single piece of conductive sheet metal
Implementation Method 2
a maximum spring travel distance to ensure a ventilation path for outgassing and a minimum spring travel distance to accommodate varying cell lengths
Data Source
AI summary
The present disclosure describes a non-welded leaf spring battery cell connector which allows for unrestricted outgassing during Lithium-Ion thermal runaway. The connector also has a low-resistance electrical connection surface for applications with rough, uneven contact surfaces such as those on refurbished Lithium-Ion battery cells. The connector is compatible with both protected and unprotected Lithium-Ion cells, as it allows for up to about 5 mm of vertical travel to support varying battery cell lengths caused by battery protection circuits. The leaf spring connector for Lithium-Ion battery cells is made of a conductive sheet of metal, cut and folded into a leaf-spring connector for a removable, non-welded battery cell. The leaf spring connector has one or more areas of material removed, as to not block the flow of caustic gasses during emergency outgassing.