Rigidized Battery Pack Housing for Cell Edge Stress Relief
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Solution Overview
Problem
Conventional vehicle battery packs face reliability issues due to stress concentrations at weld joints and edges, leading to mechanical failure and electrolyte leaks, which limits their durability and energy density.
Innovation Solution
The battery pack design incorporates a recessed adhesive layer and varying thickness in the cover and base to reduce stress on the battery cells, with optional L-shaped brackets to distribute loads and increase rigidity, thereby enhancing the structural integration of cells within the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cells are bonded with adhesives to the pack housing to increase stiffness, then the overall pack stiffness is improved, but reliability deteriorates due to adhesive pulling cells open in high stress areas
Solution Approach 1:
The adhesive layer is designed with spatially varying thickness: thicker at edge regions near weld joints and thinner at central regions. This local differentiation allows the adhesive to provide enhanced stress distribution and protection at vulnerable edge areas while maintaining adequate bonding strength in central regions, thereby resolving the contradiction between pack stiffness and bonding reliability.
2Quantity of substance
If thin aluminum housings are used for battery cells to improve energy density, then energy density is improved, but reliability deteriorates due to reduced mechanical strength at stress concentration points
Solution Approach 1:
The cover and base are designed with varying thickness: thinner in central regions to maximize energy density and lighter weight, and thicker at edge regions to provide enhanced mechanical strength and stress distribution at vulnerable locations. This local thickness differentiation resolves the contradiction between energy density and mechanical strength.
3Reliability
If welds are added to seal prismatic and cylindrical cells, then sealing reliability is improved, but reliability deteriorates due to creases that reduce mechanical strength at weld locations
Solution Approach 1:
The thicker adhesive layer is applied beforehand at edge regions near expected weld locations to create a cushioning effect. This pre-applied adhesive layer compensates for the mechanical strength reduction caused by weld creases, distributing stresses and preventing failure at these vulnerable locations while maintaining the necessary sealing function.
4Strength
If adhesive layer thickness is increased uniformly across the cover to improve bonding, then bonding strength is improved, but device complexity increases due to additional material and assembly requirements
Solution Approach 1:
Rather than uniformly increasing adhesive thickness, the solution applies thicker adhesive only at specific edge regions where stress concentrations occur, while maintaining thinner adhesive in central regions. This localized approach provides necessary bonding strength at critical locations without the complexity and material costs of uniform thickness increase.
Data Source
AI summary
A battery pack can include a plurality of battery cells arranged adjacent one another in a row. The battery pack can include a first spacer plate aligned with and positioned adjacent the first cell of the plurality of battery cells, a second spacer plate aligned with and positioned adjacent the last cell of the plurality of battery cells, and a housing enclosing the plurality of battery cells. The housing can include a first sidewall positioned adjacent the first spacer plate and a second sidewall positioned adjacent the second spacer plate such that the plurality of battery cells can be positioned between the first sidewall and the second sidewall. The battery pack can include a cover. A layer of adhesive can be disposed between the battery cells and the cover. Various techniques can be employed to improve the durability of the battery pack.