Battery Pack Separator Structure for Cell Swelling Compression
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Solution Overview
Problem
Existing battery packs in electrically powered vehicles experience significant mechanical stress due to the progressive increase in cell thickness, leading to oversized frames and increased weight, which affects vehicle performance.
Innovation Solution
The use of planar intermediate bodies with a differentiated thickness configuration, where only thicker portions are activated during initial compression phases, reducing the absolute value and gradient of the reaction force transmitted to the frame, allowing for a lighter frame design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If planar intermediate bodies with constant thickness are used between cells, then the cells are separated and compression is accommodated, but the reaction force against the frame increases with a nonlinear gradient leading to oversized and heavy frame design
Solution Approach 1:
The planar intermediate body is designed with non-uniform thickness, featuring a first region with greater thickness and a second region with lesser thickness. This local variation in geometry allows different zones to provide different levels of compression resistance, reducing the peak reaction force transmitted to the frame while maintaining adequate cell separation and compression accommodation throughout the cell's lifecycle.
Solution Approach 2:
The thickness parameter of the planar intermediate body is deliberately varied across different regions rather than maintaining a constant value. By changing the thickness parameter locally, the compression characteristics and reaction force profile are optimized to reduce the gradient during compression, thereby allowing for a lighter frame design that still provides sufficient structural support.
2Reliability
If the frame is sized to withstand the stress from cell thickening, then the battery pack can accommodate cell expansion, but the frame becomes oversized and the battery pack weight increases
Solution Approach 1:
The non-uniform thickness distribution in the planar intermediate body creates zones of varying compliance. The thicker first region provides enhanced cushioning where needed, while the thinner second region allows for controlled compression. This local differentiation enables the system to accommodate cell thickening reliably while transmitting reduced peak stresses to the frame, permitting a lighter frame design.
Solution Approach 2:
The planar intermediate body with differentiated thickness is pre-configured to provide optimized cushioning throughout the cell's operational lifecycle. The varying thickness profile is designed in advance to match the expected compression trajectory, ensuring that stress is distributed more favorably during cell thickening, thereby protecting the frame from excessive loads and enabling weight reduction.
3Ease of manufacture
If planar separators with constant thickness are used, then the structure is simple to manufacture, but the compression generates high reaction forces with nonlinear development against the frame
Solution Approach 1:
The planar intermediate body incorporates local quality variations through its non-uniform thickness profile, with a first region of greater thickness and a second region of lesser thickness. This geometric differentiation allows the separator to generate a more favorable compression response with reduced reaction forces, while still maintaining a relatively simple planar structure that can be manufactured using conventional processes.
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 configuration results in reduced mechanical stress on the frame, enabling a lighter battery pack and improved vehicle performance without altering initial dimensions or materials.
Implementation Method 1
The planar intermediate body (51) is configured to compress during the progressive increase in thickness of the cells (C)
Implementation Method 2
generate, during the life of the battery, a smaller reaction force in absolute value with a smaller gradient or ramp as a function of compression
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Battery pack for an electrically powered road vehicle; wherein the battery pack comprises: a plurality of planar electrochemical cells arranged in a pack along an axis A; a box-shaped support structure housing the cells; wherein each cell comprises two flat faces orthogonal to the axis A and a thickness s1 along the axis A progressively increasing during the life of the battery pack; wherein between each pair of adjacent cells there is a planar intermediate body in contact with the flat faces of the cells; wherein each planar intermediate body is configured to compress during the progressive increase in thickness s1 of the cells; wherein each planar intermediate body comprises a flat face orthogonal to the axis A contacting the flat face of a first cell of the pair of cells; wherein at least one of the planar intermediate bodies comprises portions with a differentiated thickness s2, s3 along the axis A.