Solid-State Battery Protective Layer for Crack Suppression
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Solution Overview
Problem
Conventional solid state batteries face issues with crack generation on the surface during charging and discharging due to tensile stress caused by the expansion of electrode layers, which can lead to moisture intrusion and impaired ion movement.
Innovation Solution
The solid state battery incorporates a protective layer with a side portion configuration where the first thickness dimension of a central region is larger than the second thickness dimension of other portions, effectively dispersing stress and preventing crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer with uniform thickness is used, then the manufacturing process is simple, but cracks are generated on the battery surface due to tensile stress during charging and discharging
Solution Approach 1:
The protective layer is designed with different thicknesses in different regions: a first thickness in the central portion and a second thickness (smaller than the first) in the side portions. This local quality variation allows the central portion to better withstand tensile stress during electrode expansion, preventing crack generation while maintaining overall protective function.
2Reliability
If the protective layer thickness is increased throughout, then crack resistance is improved, but the battery element size increases and manufacturing complexity increases
Solution Approach 1:
Instead of uniformly increasing the protective layer thickness throughout the entire battery element, the invention applies increased thickness (first thickness) only to the central portion where tensile stress is maximized during electrode expansion. The side portions maintain a smaller second thickness, thereby achieving crack suppression at the critical location without unnecessarily increasing overall battery dimensions.
3Reliability
If a thicker protective layer is used in the central portion, then stress dispersion is improved and cracks are suppressed, but manufacturing precision requirements increase
Solution Approach 1:
The protective layer is designed with different thicknesses in different regions: a first thickness in the central portion and a second thickness (smaller than the first) in the side portions. This local quality variation allows the central portion to better withstand tensile stress during electrode expansion, preventing crack generation while maintaining overall protective function.
Data Source
AI summary
A solid state battery that includes: a battery element including, along a stacking direction, one or more battery constituent units including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer; first and second external terminals joined to an extended portion of each electrode layer of the positive electrode layer and the negative electrode layer, respectively; and a protective layer that covers a surface of the battery element other than the extended portions of each electrode layer, the protective layer including a side portion on a central region of a side portion of the battery element extending in substantially the same direction as the stacking direction and in which a first thickness dimension of a first portion is larger than a second thickness dimension of a second portion other than the first portion.