Laminate Cathode Thin Film Part Crack Prevention
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Solution Overview
Problem
All-solid-state batteries face deterioration due to cracks in the anode layer, which concentrate current and lead to performance issues, particularly when the cathode layer's area is smaller than the anode layer's area, causing cracks to form during high-pressure pressing and affecting battery performance.
Innovation Solution
A laminate structure is designed with a cathode layer having a thinner end part and a space part formed by a level difference, which can be filled with electroconductive material or adhesive, enhancing electroconductivity and adhesion, thus reducing resistance and suppressing crack formation and current concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cathode layer area is made smaller than the anode layer area, then the battery structure is simplified and manufacturing is easier, but cracks form during high-pressure pressing and current concentration occurs leading to deterioration
Solution Approach 1:
The cathode layer is designed with non-uniform thickness, featuring a thin film part at the end portion and a thick film part at the central portion. This local quality variation allows the end portion to be more compliant during pressing, preventing crack formation while maintaining the overall simplified battery structure where cathode area is smaller than anode area.
Solution Approach 2:
The cathode layer is pre-formed with a specific thickness distribution (thin at ends, thick at center) before the pressing process. This preliminary structural preparation ensures that during subsequent high-pressure pressing, the thin film parts at the ends can deform more easily, preventing crack initiation while the thick film part maintains structural integrity.
2Strength
If high-pressure pressing is applied to the laminate, then good contact between layers is achieved, but cracks form starting from the cathode end edge to the anode end part
Solution Approach 1:
The cathode layer exhibits local quality variation in thickness, with thinner regions at the ends and thicker region at the center. This allows differential deformation behavior during pressing: the thin film parts at ends can compress more easily without cracking, ensuring good interlayer contact, while the thick film part maintains structural stability.
Solution Approach 2:
The thin film parts at the cathode layer ends act as built-in cushioning elements that deform preferentially during pressing, absorbing compressive stress and preventing stress concentration that would otherwise cause cracks to form and propagate through the laminate structure.
3Quantity of substance
If the anode layer area is larger than the cathode layer area, then the battery can accommodate more anode material for higher capacity, but the exposed anode end parts are prone to cracking and current concentration
Solution Approach 1:
The cathode layer is designed with local quality variation where the thin film parts at the ends extend closer to the anode layer edges, providing electroconductive coverage at the exposed anode end regions. This prevents current concentration and crack formation at the anode ends while still allowing the anode area to be larger than cathode area for higher capacity.
Data Source
AI summary
Provided is a laminate that is configured to suppress a deterioration in the all-solid-state battery even if the end part of the anode layer is cracked. The laminate may be a laminate comprising an anode layer, a solid electrolyte layer and a cathode layer in this order, wherein an area in a planar direction of the cathode layer is smaller than an area in a planar direction of the anode layer; wherein an end part of the cathode layer comprises, on the solid electrolyte layer, a thin film part having a smaller thickness than a thickness of a central part of the cathode layer; and wherein the end part of the cathode layer comprises, on the thin film part, a space part formed by a level difference between the thin film part and the central part.