Battery Stack Elastic Member Layout for Load Variation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power storage systems, such as battery packs, face issues with load variation due to cell expansion, where a highly rigid lid portion applies uneven pressure, leading to significant repulsive forces and load variations on the laminated body.
Innovation Solution
A power storage system with a stack of cells, a case, and an elastic member comprising a first and second elastic portion, where the first elastic portion has a lower elastic modulus in the direction of lid opposition, allowing it to compress more and distribute pressure evenly, thereby suppressing deformation and load variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a highly rigid lid portion is used to apply load to the laminated body, then the pressing pressure can be maintained, but large repulsive force is applied when the cell expands causing variation in load magnitude
Solution Approach 1:
The elastic member is designed with different elastic moduli in different regions: the first elastic portion (central region) has a lower elastic modulus to allow greater compression and reduce repulsive force, while the second elastic portion (side regions) has a higher elastic modulus to maintain structural support. This local differentiation resolves the contradiction by allowing each region to perform its specific function.
Solution Approach 2:
The patent changes the elastic modulus parameter of the elastic member in different regions and directions. Specifically, the elastic modulus in the first direction (stack thickness direction) of the first elastic portion is lower than that of the second elastic portion, enabling the central region to compress more during cell expansion while side regions maintain rigidity.
2Stress or pressure
If the first lid member is formed from an elastic film to apply pressure, then the pressing pressure can be applied, but constituent members such as pressure sensor and decompressor are required increasing device complexity
Solution Approach 1:
The elastic member is designed to automatically adjust the pressing pressure on the laminated body through its elastic deformation characteristics. When the cell expands or contracts, the elastic member self-adjusts the force distribution without requiring external sensors or control systems, making the system self-regulating and eliminating the need for pressure sensors and decompressors.
Solution Approach 2:
The elastic member acts as an intermediary between the lid portion and the laminated body, transferring and distributing the load while absorbing expansion forces. This intermediary structure eliminates the need for complex pressure control systems by providing passive mechanical compliance.
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 system effectively suppresses load variation and deformation of the lid portion during cell expansion, ensuring consistent pressure application to the stack, reducing the magnitude of the load applied by the lid portion.
Implementation Method 1
The elastic member includes a first elastic portion and a second elastic portion. An elastic modulus in the first direction of the first elastic portion is lower than an elastic modulus in the first direction of the second elastic portion.
Implementation Method 2
When a portion of the stack located most distant from the opening end in the second direction tends to deform with expansion of the cell, the first elastic portion is relatively greatly compressed by repulsive force of the lid portion, because the elastic modulus in the first direction of the first elastic portion is lower than the elastic modulus in the first direction of the second elastic portion.
Data Source
AI summary
A power storage includes a stack, a case, a lid portion, and an elastic member. The lid portion is fixed to an opening end of the case to cover the opening. The elastic member is located between the stack and the lid portion. The elastic member includes a first elastic portion and a second elastic portion. The first elastic portion includes a portion of the elastic member located most distant from the opening end in a second direction orthogonal to a first direction which is a direction in which the stack and the lid portion are opposed to each other. The second elastic portion is located on opposing sides of the first elastic portion in the second direction. An elastic modulus in the first direction of the first elastic portion is lower than an elastic modulus in the first direction of the second elastic portion.