Elastic Plates for Battery Cell Compression
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Solution Overview
Problem
Lithium-ion battery cells experience cyclic volumetric changes during charge and discharge, requiring a module assembly structure that can accommodate dimensional changes while maintaining a specified compression force to ensure cell capacity and longevity.
Innovation Solution
Incorporating elastic members with contoured plates between cells, manufactured using common processes like metal stamping or plastic sheet forming, to provide a compression force that accommodates cell expansion and maintains required pressure, ensuring uniform cell support and extended battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid cell support structures are used to maintain compression force, then cell capacity is maintained, but the structure cannot accommodate cyclic volumetric changes during charge and discharge
Solution Approach 1:
The patent employs elastic members with contoured plates that have flexible surfaces capable of deforming to accommodate cell volume changes. These flexible plates maintain compression force while adapting to the cyclic dimensional changes of lithium-ion cells during charge and discharge cycles.
Solution Approach 2:
The elastic members are designed with varying thickness parameters across the plate surface, creating regions of different stiffness. This parameter variation allows the structure to provide appropriate compression force while accommodating dimensional changes, resolving the contradiction between maintaining reliability and adapting to volume changes.
2Reliability
If uniform compression force is applied to cells, then cell capacity is maintained, but cyclic expansion causes non-uniform pressure distribution
Solution Approach 1:
The contoured plates feature locally varied thickness and contour profiles that create different stiffness characteristics in different regions. This local quality variation ensures that pressure is uniformly distributed across the cell surface despite cyclic expansion, as each region of the plate provides appropriate local compliance.
Solution Approach 2:
The plates incorporate curved and contoured surfaces rather than flat rigid surfaces. This curvature allows the plates to conform to the expanding cell geometry while maintaining uniform pressure distribution, preventing localized stress concentrations that would occur with rigid flat plates.
3Ease of manufacture
If simple plate structures are used for elastic members, then manufacturing is simplified, but the ability to provide specified compression force while accommodating expansion is reduced
Solution Approach 1:
The patent achieves complex functional requirements through relatively simple parameter variations in the plate design, such as thickness gradients and contour profiles. These parameter changes can be implemented using standard manufacturing processes like metal stamping or plastic sheet forming, maintaining ease of manufacture while achieving the required compression force and expansion accommodation.
Solution Approach 2:
The use of thin flexible plate structures allows for complex three-dimensional contours to be formed through relatively simple manufacturing processes. The flexibility of thin films enables the plates to accommodate cell expansion while maintaining compression force, achieving both manufacturing simplicity and functional reliability.
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 members effectively manage cyclic expansion, maintain compression force, and maximize battery cell lifetime by allowing for cell growth while ensuring consistent pressure distribution across the cells.
Implementation Method 1
elastic members with contoured plates between cells, manufactured using common processes like metal stamping or plastic sheet forming, to provide a compression force that accommodates cell expansion
Data Source
AI summary
A battery pack includes a battery housing and electrochemical cells disposed in the battery housing in a stacked configuration. Elastic members are disposed between adjacent cells of a cell stack. Each elastic members is formed as a plate (e.g., a single-thickness sheet) having a curved or wavy contour when seen in cross-section, and is configured to serve as a compression spring that provides a predetermined compression force to adjacent cells while accommodating cell growth during use. The elastic members may include surface features such as strategically shaped and/or located protrusions 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.