All-Solid-State Electrochemical Cell Thermal Expansion Matching
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Solution Overview
Problem
In electrochemical cells with all-solid-state electrode bodies, thermal expansion coefficient mismatches between the electrode body and the exterior body lead to stress, voids, and cracking issues, compromising conduction and sealing properties, particularly in small-size cells used in watches and electronic components.
Innovation Solution
The electrochemical cell design ensures thermal expansion coefficients of the electrode body, first case, second case, and sealing member are all 10×10−6/°C or lower, with options including metallic, ceramic, and glass materials, and the use of a spring portion or cushion material to mitigate stress and maintain adhesiveness and conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal expansion coefficients of electrode body and exterior body are significantly different, then joining and sealing can be achieved, but stress is exerted between components causing voids or cracks that compromise conduction and sealing properties
Solution Approach 1:
The patent applies parameter changes by carefully selecting materials for the electrode body, first case, second case, and sealing member such that all have thermal expansion coefficients of 10×10−6/°C or lower. This parameter matching resolves the technical contradiction by eliminating differential thermal expansion stress that would otherwise cause voids or cracks during heating and cooling cycles, thereby maintaining both reliable conduction properties and structural integrity.
2Reliability
If thermal expansion coefficients of electrode body and exterior body are significantly different, then joining and sealing can be achieved, but voids are generated between components that compromise sealing properties
Solution Approach 1:
The patent resolves this contradiction by changing the material parameters of all components (electrode body, cases, and sealing member) to have matched thermal expansion coefficients of 10×10−6/°C or lower. This prevents differential contraction during cooling after heating treatments, eliminating void formation between the electrode body and exterior body components, thereby ensuring both stable composition and reliable sealing properties.
3Productivity
If multiple positive and negative electrode layers are laminated together to improve current rates and temperature characteristics, then performance is improved, but the strength of the electrode body becomes low
Solution Approach 1:
The patent addresses this contradiction by changing the material parameters of the electrode layers and solid electrolyte to achieve a balance between thin-layer performance and structural strength. By optimizing the composition and properties of the solid electrolyte and electrode materials, the patent enables the use of multiple thin laminated layers for improved current rates while maintaining sufficient electrode body strength through material property adjustments rather than increasing layer thickness.
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 approach enhances the reliability and service life of electrochemical cells by ensuring consistent conduction and sealing properties, reducing the risk of cracking and improving thermal management.
Implementation Method 1
an all-solid-state electrode body in which a positive electrode layer and a negative electrode layer are laminated together through a solid electrolyte
Implementation Method 2
thermal expansion coefficients of the electrode body, the first case, the second case, and the sealing member are all 10×10−6/° C. or lower
Data Source
AI summary
An electrochemical cell includes an all-solid-state electrode body in which a positive electrode layer and a negative electrode layer are laminated together through a solid electrolyte and an exterior body having a cavity in which the electrode body is stored. The exterior body has a first case and a second case which sandwich the electrode body and a sealing member that defines the cavity together with the first case and the second case by joining the first case and the second. The thermal expansion coefficients of the electrode body, the first case, the second case, and the sealing member are all 10×10−6/° C. or lower.