All-Solid-State Battery Electrolyte Roughness for Crack Suppression
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Solution Overview
Problem
Existing all-solid-state batteries face the risk of crack propagation between solid electrolyte layers due to stress from active material expansion and contraction, leading to short circuits.
Innovation Solution
The battery design includes specific surface roughness ratios between solid electrolyte layers and electrode layers, with a manufacturing method involving controlled lamination pressures to prevent crack propagation, using materials like metallic lithium and sulfur for electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two solid electrolyte layers are interposed between the positive electrode layer and the negative electrode layer, then the risk of pinholes is reduced, but crack propagation between layers may still occur due to stress from active material expansion and contraction
Solution Approach 1:
The patent applies different surface roughness characteristics to different solid electrolyte layers. Specifically, the first solid electrolyte layer has a maximum height Rz1 and the second solid electrolyte layer has a maximum height Rz2, where the ratio Rz1/Rz2 is controlled within 0.15-0.25. This local differentiation of surface properties creates asymmetric stress distribution that prevents crack propagation between layers while maintaining pinhole prevention.
2Reliability
If high pressure is applied during lamination to ensure good contact between layers, then ionic conduction is improved, but crack propagation may be induced due to stress on the solid electrolyte layers
Solution Approach 1:
The patent controls the surface roughness parameters (Rz1 and Rz2) of the solid electrolyte layers within specific ranges, with the ratio Rz1/Rz2 between 0.15-0.25. This parameter optimization allows the layers to achieve good contact and ionic conduction while the asymmetric roughness profile prevents stress concentration that would lead to cracks under lamination pressure.
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 design effectively suppresses crack propagation, enhancing short-circuit resistance and ensuring stable ionic conduction paths, thereby improving the safety and reliability of the battery.
Implementation Method 1
a maximum height Rz1 of the first surface and a maximum height Rz2 of the second surface satisfy a relation (1) below: 0.15≤Rz1/Rz2≤0.25
Data Source
AI summary
An all-solid-state cell, having improved short-circuit resistance, comprises a first electrode layer, a first solid electrolyte layer, a second solid electrolyte layer, and a second electrode layer in this order, wherein the first solid electrolyte layer has a first surface, the second solid electrolyte layer has a second surface in contact with the first surface, and a maximum height Rz1 of the first surface and a maximum height Rz2 of the second surface satisfy the following relation (1):0.15≤Rz1/Rz2≤0.25 (1)