Elastic Bladder Battery Cell Compression Spring
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Solution Overview
Problem
Lithium-ion battery cells experience cyclical volume changes due to variations in state of charge, requiring a module assembly structure that can accommodate dimensional changes while maintaining a specified compression force to ensure cell capacity over the life of the battery.
Innovation Solution
Incorporating an elastic member between cells, formed by two sheets bonded along sealed lines and filled with fluid, which acts as a compression spring to provide a predictable and uniform compression force, accommodating cell expansion and contraction while maintaining required compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If cells are arranged in a rigid stack without elastic members, then structural stability is improved, but the structure cannot accommodate cyclical volume changes of cells during charge and discharge
Solution Approach 1:
The patent employs elastic members with flexible membranes that can deform to accommodate cell volume changes while maintaining structural integrity. These flexible elements allow the battery stack to adapt to cyclical expansion and contraction of cells during charge-discharge cycles without compromising overall structural stability.
Solution Approach 2:
The invention introduces dynamic elements (elastic members) into the rigid cell stack structure. These elastic members can dynamically adjust their deformation state based on cell volume changes, transitioning between compressed and relaxed states to accommodate the cyclical nature of battery operation while maintaining structural coherence.
2Adaptability or versatility
If elastic members are added between cells to accommodate volume changes, then adaptability is improved, but device complexity increases
Solution Approach 1:
The elastic members utilize thin flexible membranes that provide the necessary compliance for volume accommodation without requiring complex mechanical structures. The simplicity of the membrane-based design minimizes additional components while achieving the desired adaptability.
Solution Approach 2:
The elastic members are inflated with fluid to provide the necessary elastic force. This pneumatic approach simplifies the structure by using fluid pressure to generate the elastic response, avoiding the need for complex mechanical springs or actuators.
3Reliability
If uniform compression force is applied to cells, then cell capacity is maintained, but the structure cannot accommodate non-uniform expansion of cells
Solution Approach 1:
The elastic members are designed with non-uniform thickness distribution, where different regions of the membrane have different thicknesses to provide varying local stiffness. This allows the structure to apply uniform overall compression while accommodating local non-uniform expansions of the cells through regions with appropriate compliance.
Solution Approach 2:
The invention changes the physical parameters of the elastic members, specifically the thickness of the membrane in different regions. By varying the thickness parameter spatially, the structure achieves both uniform compression force application and localized adaptability to non-uniform cell expansion patterns.
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 elastic member effectively manages cell growth, maintains compression force, and maximizes battery lifetime by allowing controlled expansion and contraction, ensuring consistent performance and longevity.
Implementation Method 1
an elastic member disposed between the first cell and the second cell... acts as a compression spring to provide a predictable and uniform compression force, accommodating cell expansion and contraction
Implementation Method 2
One of the first interior space and the second interior space is at least partially inflated, and the other of the first interior space and the second interior space is less inflated than the one of the first interior space and the second interior space
Data Source
AI summary
A battery pack includes a battery housing and electrochemical cells disposed in the battery housing in a stacked configuration. Elastic bladders are disposed between adjacent cells of a cell stack. The elastic bladders are configured to serve as a compression spring that provide a predetermined compression force to each cell while accommodating cell growth during use. The elastic bladders may include surface features such as strategically shaped and/or located protrusions or restrained regions that are configured to permit compliance and can be tuned to address the requirements of a specific application and permit application of varying stiffness characteristics across a surface of a cell.