Wavy Battery Stack Fastening Members for Cell Expansion Absorption
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Solution Overview
Problem
Conventional power supply devices for electric vehicles and power storage systems face challenges in following the expansion and contraction of secondary battery cells due to the low elasticity of metal binding bars, which can lead to stress concentration and potential breakage.
Innovation Solution
A power supply device with a wavy portion in the fastening members that absorb displacement and maintain the fastened state, allowing for deformation to accommodate the expansion of secondary battery cells, while using an insulating sheet to prevent electrical interference and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal binding bar is used to fasten end plates, then the fastening strength is sufficient, but the binding bar cannot follow the expansion and contraction of battery cells due to low elasticity
Solution Approach 1:
The binding bar is designed with a wavy portion that can dynamically change shape during battery expansion and contraction. The wavy structure allows the binding bar to flex and adapt to cell deformation while maintaining fastening force, resolving the contradiction between structural strength and adaptability to deformation.
Solution Approach 2:
The binding bar's physical parameters are changed by introducing a wavy portion with specific geometric characteristics (wave height, wave length, curvature radius). These parameter changes enable the binding bar to exhibit both sufficient strength and elastic deformation capability, allowing it to follow battery cell expansion and contraction.
2Quantity of substance
If the capacity of secondary battery cells is increased, then the energy storage capability is improved, but the expansion amount increases and the load on the binding bar increases
Solution Approach 1:
The binding bar's geometric parameters (wave height h, wave length l, curvature radius r) are optimized to handle increased expansion forces from high-capacity cells. The wavy structure distributes the expansion load across multiple wave sections, reducing peak stress while accommodating larger dimensional changes associated with higher capacity batteries.
3Ease of manufacture
If a straight binding bar is used, then the manufacturing is simple, but it cannot absorb displacement during battery expansion
Solution Approach 1:
The binding bar incorporates a wavy portion with curved geometry instead of a straight configuration. This curvature allows the binding bar to absorb expansion displacement through elastic deformation of the waves while maintaining manufacturing feasibility through standard forming processes, thus preserving both ease of manufacture and 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 solution effectively absorbs expansion and contraction of battery cells, maintaining the fastened state and reducing the risk of breakage, thereby enhancing the reliability and longevity of the power supply device.
Implementation Method 1
Each of the plurality of fastening members has a wavy portion in which a plurality of wavy pieces bent in a cross-sectional view are periodically disposed at an interval according to the cell thickness. Even if the battery stack body becomes long in the stack direction due to expansion of the secondary battery cells, the wavy portion is deformed, so that displacement of the battery stack body can be absorbed and the fastened state can be maintained.
Data Source
AI summary
Power supply device includes: a plurality of secondary battery cells each having a prismatic exterior can and constant cell thickness; a pair of end plates covering both end surfaces of battery stack body in which the plurality of secondary battery cells are stacked; and a plurality of fastening members each having a plate shape extending in a stack direction of the plurality of secondary battery cells and disposed on an opposing side surface of battery stack body to fasten end plates to each other. Each of the plurality of fastening members has wavy portion in which a plurality of wavy pieces bent in a cross-sectional view are periodically disposed at an interval according to the cell thickness.