Laminated Solid-State Battery Electrolyte Layout for Crack Suppression
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Solution Overview
Problem
Laminated all-solid-state batteries face issues with increased internal resistance and insufficient cycle characteristics due to stress concentration and potential cracking from volume expansion and contraction of electrode layers, particularly in solid electrolyte layers with varying porosity.
Innovation Solution
A laminated all-solid-state battery design with alternating layers of solid electrolytes, including a first group with a smaller thickness and a second group with twice or more the thickness of the first, ensuring a ratio of 2:1 to 10:1, and using electrolytes with the same crystal structure to distribute stress uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte layer with high porosity is provided to alleviate internal stress, then cycle characteristics improve, but internal resistance increases and cracks occur more easily
Solution Approach 1:
The patent applies local quality by creating a solid electrolyte layer with non-uniform porosity distribution: a first region with higher porosity (30-70%) near the electrode interface to accommodate volume expansion and reduce stress concentration, and a second region with lower porosity (10-50%) in the interior to maintain low internal resistance and high ionic conductivity. This spatial variation in porosity resolves the contradiction between stress relief and resistance reduction.
2Reliability
If a solid electrolyte layer with high porosity is provided to alleviate internal stress, then cycle characteristics improve, but cracks occur more easily in the solid electrolyte layer
Solution Approach 1:
The patent uses local quality by concentrating the high porosity (30-70%) in the first region adjacent to the electrode where stress from volume expansion occurs, while maintaining lower porosity (10-50%) in the second region. This localized high porosity acts as a stress buffer zone that absorbs expansion forces, protecting the lower porosity regions from crack initiation and propagation.
Solution Approach 2:
The patent implements beforehand cushioning by pre-designing the high porosity first region as a stress buffer zone before volume expansion occurs during charging. This porous structure anticipates and accommodates the electrode's volume expansion, preventing stress concentration that would otherwise lead to crack formation in the solid electrolyte layer.
Data Source
AI summary
A laminated all-solid-state battery includes a laminate having positive electrode and positive electrode active material layers, negative electrode layers having negative electrode current collector and negative electrode active material layers, and solid electrolyte layers. The positive and negative electrode layers are alternately laminated with the solid electrolyte layers interposed. The solid electrolyte layers include solid electrolyte layers belonging to first and second groups, the second thicker than the first. The first group includes a first solid electrolyte layer being thinnest. The second group is composed of a second solid electrolyte layer having a thickness of twice or more that of the first. A relationship (1) is satisfied when an average thickness of the plurality of solid electrolyte layers belonging to the first group is defined as ta and an average thickness of the solid electrolyte layers belonging to the second group is defined as tb; 2ta≤tb . . . (1).