Flat Solid-State Battery Cushioning for Crimp Stress Relief
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Solution Overview
Problem
Flat-shaped all-solid batteries face reliability issues due to cracks in electrodes caused by stress during crimping, leading to compromised capacity and decreased productivity, especially when using traditional outer casings that apply significant pressure on the electrodes.
Innovation Solution
Incorporating a conductive porous member, such as a flexible graphite sheet, between the electrode stack and the inner surfaces of the outer and sealing cans to absorb and relieve compressive forces, thereby reducing the likelihood of cracks and maintaining conduction during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional outer casing with crimping process is used, then the battery structure is sealed and protected, but cracks occur on the electrode particularly near the sealing can
Solution Approach 1:
An elastic body is introduced as an intermediary component between the outer can and the positive electrode, and between the sealing can and the negative electrode. This elastic body acts as a stress-absorbing mediator that prevents direct transmission of crimping stress to the electrodes, thereby preventing cracks while maintaining the sealing function of the outer casing.
Solution Approach 2:
The elastic body is placed in advance between the cans and electrodes to provide beforehand cushioning against the crimping stress. This pre-positioned cushioning layer absorbs the mechanical stress during the crimping process before it can reach and damage the electrodes, ensuring electrode integrity from the outset.
2Reliability
If the outer can is crimped inwardly to seal the battery, then the sealing is achieved, but stress is applied to the electrode causing cracks
Solution Approach 1:
The elastic body serves as a mediator that decouples the sealing function from the stress application. It allows the outer can to be crimped for sealing while preventing the stress from being transmitted to the electrode, thus protecting electrode strength while achieving sealing integrity.
Solution Approach 2:
The elastic body functions as a flexible protective layer that can deform under crimping stress and then recover, providing a flexible buffer between the rigid outer can and the fragile electrode. This flexible layer maintains sealing while protecting the electrode from stress-induced cracks.
3Reliability
If elastic body is disposed between outer can and electrode, then crack prevention is improved, but additional component and assembly step are required
Solution Approach 1:
The elastic body performs multiple functions simultaneously: it prevents cracks by absorbing stress, maintains electrical contact between the can and electrode, and provides a sealing barrier. By combining multiple functions into a single component, the overall device complexity is minimized despite the addition of this element.
Solution Approach 2:
The elastic body merges the functions of stress absorption, electrical conduction, and sealing into a single integrated component. This consolidation reduces the number of separate parts needed and simplifies the assembly process, as the elastic body can be placed in one step to achieve multiple protective functions.
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 use of conductive porous members enhances the reliability and productivity of flat-shaped all-solid batteries by preventing electrode cracks and maintaining effective conduction, even under repeated charge cycles, while ensuring high capacity retention rates.
Implementation Method 1
a conductive porous member constituted by a molded body of graphite and having flexibility is disposed between the stack and an inner bottom surface of the outer can or an inner bottom surface of the sealing can
Implementation Method 2
The conductive porous member is constituted by a molded body of graphite and having flexibility
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A flat-shaped all-solid battery described in this application includes a battery container constituted by an outer can and a sealing can and a stack which a positive electrode, a solid electrolyte layer, and a negative electrode are stacked to form. The stack is housed in the battery container. A conductive porous member constituted by a molded body of graphite and having flexibility is disposed between the stack and an inner bottom surface of the outer can or an inner bottom surface of the sealing can. Moreover, in the above flat-shaped all-solid battery, the conductive porous member can be disposed between the stack and the inner bottom surface of the sealing can, and between the stack and the inner bottom surface of the outer can.