Battery Compression Case Using Expanding Foam Stack Pressure
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Solution Overview
Problem
Existing battery technologies face challenges in providing sufficient stack pressure for solid-state pouch cells to counteract volume growth during charging and discharging, while also ensuring compliance with volume expansion, which affects the interfacial contact and longevity of these cells.
Innovation Solution
The use of expanding foam, such as expanding foam epoxy, is injected into the battery casing to fill the remaining volume and apply a predetermined pressure greater than 1 MPa, allowing the foam to expand and set while maintaining pressure on the battery cells, thus providing the necessary stack pressure and compliance for volume growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If expanding foam is injected into the battery casing to fill remaining volume and apply pressure, then stack pressure on battery cells is improved, but device complexity increases
Solution Approach 1:
The foam's expansion ratio and density are carefully controlled to achieve the desired stack pressure. By adjusting the foam's physical parameters (expansion volume, density between 0.4-1.2 g/cm³), the system provides sufficient pressure (1-10 MPa) on battery cells without requiring complex mechanical pressure application mechanisms
Solution Approach 2:
The patent replaces complex mechanical pressure application systems with a chemical expansion process. Instead of using mechanical actuators, springs, or hydraulic systems to maintain pressure, the invention uses expanding foam that chemically expands to fill voids and apply pressure, significantly simplifying the overall device structure
2Stress or pressure
If foam density is increased to provide sufficient stack pressure, then pressure on battery cells is improved, but weight of battery increases
Solution Approach 1:
The foam density is optimized within a specific range (0.4-1.2 g/cm³) to achieve the necessary stack pressure while minimizing weight. This parameter optimization allows the foam to provide sufficient pressure (1-10 MPa) on battery cells without excessive weight addition to the overall battery system
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 solution effectively maintains the desired stack pressure on solid-state pouch cells, enhancing their interfacial contact and longevity by allowing for compliance with volume expansion, while also reducing weight and improving efficiency in electric vehicles, thereby contributing to reduced greenhouse gas emissions.
Implementation Method 1
an expanding foam may be injected into an internal volume of a casing of a battery or battery unit in which one or more cells (e.g., pouch cells, such as a solid-state pouch cells) are disposed. The expanding foam may have a maximum expanded volume that is larger than the remaining volume within the casing, and the expanding foam may therefore expand to substantially fill the remaining volume within the casing
Implementation Method 2
The stack pressure provided by the foam may be as much as, or more than, 1 MPa-5 MPa in various implementations
Data Source
AI summary
Aspects of the disclosure relate to the use of an expanding foam to provide a stack pressure for battery cells such as solid-state pouch cells. In one or more implementations, a battery, a battery unit, a battery module or a battery pack is provided with one or more battery cells within an internal volume of a casing. An initial volume of an expanding foam is introduced into the internal volume, and allowed to expand to substantially fill a remaining portion of the internal volume and to provide the stack pressure on the battery cells.