Battery Cell Stack Fastening for Uniform Pressure and High Energy Density
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Solution Overview
Problem
Existing battery modules face issues with non-uniform residual load and increased space occupancy due to varying elastic modulus and the need for additional components, leading to decreased energy density, particularly in solid secondary batteries using solid electrolytes.
Innovation Solution
A battery module design featuring through-holes in battery cells for fastening members, a center securing member, and adjustable fastening nuts to uniformly apply pressure, using lightweight materials to reduce elastic modulus and minimize component volume, with stays to absorb expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If end plates and side plates are bonded to battery cells to pressurize the stack, then the battery cells are pressurized, but the space for members increases and occupancy of battery cells decreases
Solution Approach 1:
The pressurization function is segmented from the traditional end plates and side plates into discrete pressurizing rods that pass through the battery cells. This segmentation allows the pressurization force to be applied directly through the cells rather than through external bonding structures, reducing the space occupied by pressurization members.
Solution Approach 2:
The pressurization approach transitions from a two-dimensional plate bonding method to a three-dimensional rod penetration method. The pressurizing rods extend through the stacking direction and are secured at both ends, creating a dimensional change that allows more efficient space utilization while maintaining pressurization force.
2Force
If a central portion coupling rod and peripheral portion coupling rods are used to pressurize the stack, then the stack is pressurized, but the volume occupied by members other than battery cells increases and energy density decreases
Solution Approach 1:
The pressurizing rods serve multiple functions: they provide pressurization force, act as structural support members, and eliminate the need for separate coupling rods. This multi-functionality reduces the total volume of members required while maintaining pressurization effectiveness, thereby improving energy density.
Solution Approach 2:
The design changes the structural parameters by using through-holes in the battery cells that accommodate the pressurizing rods. This parameter change allows the rods to pass directly through the cells rather than requiring additional coupling mechanisms, reducing member volume and increasing energy density.
3Force
If end plates and side plates are used with initial pressurization, then the stack is pressurized, but the residual load is not uniform due to varying elastic modulus
Solution Approach 1:
The pressurizing rods are positioned to contact the battery cells at multiple specific locations along the stacking direction. This local quality approach ensures that pressure is applied uniformly at each contact point, compensating for variations in elastic modulus and achieving more uniform residual load distribution across the stack.
Solution Approach 2:
The design creates equipotential pressure distribution by having pressurizing rods secured at both ends of the stack, which ensures that the same compressive force is applied throughout the stacking direction. This equipotential approach counteracts the non-uniform elastic modulus and achieves uniform residual load.
Data Source
AI summary
To provide a battery module capable of suitably pressurizing a stack and having high energy density. Provided is a battery module including: a cell stack in which a plurality of battery cells are stacked, the battery cells including power generation elements and exterior bodies that cover the power generation elements, in which first through-holes penetrating through the plurality of battery cells in a stacking direction are provided at center portions of the plurality of battery cells, and a fastening member that fastens the cell stack is disposed in the first through-holes.