All-solid-state battery void management for Si anode expansion
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Solution Overview
Problem
All-solid-state batteries with Si-based anode materials face challenges in balancing energy density and battery resistance due to volume expansion during charging, which requires careful management of voids in the anode layer to maintain contact with the solid electrolyte and prevent excessive pressure buildup.
Innovation Solution
Incorporating a sulfide-based solid electrolyte with strategically placed voids within the anode layer, allowing for a controlled percentage of voids surrounded by the solid electrolyte, ranging from 3.4 to 29.6 vol%, to absorb expansion and maintain contact with the anode active material, thereby reducing battery resistance and confining pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the number of voids in the anode layer is increased to suppress battery swelling, then battery expansion is reduced, but contact between the anode active material and the solid electrolyte may be compromised, leading to increased battery resistance
Solution Approach 1:
The patent applies local quality by creating voids with specific characteristics (surrounded by solid electrolyte, specific size distribution, and strategic placement) rather than uniform voids throughout the anode layer. This localized approach allows voids to serve the function of accommodating Si expansion while maintaining adequate contact between anode active material and solid electrolyte in other regions, thus resolving the contradiction between suppressing swelling and maintaining low resistance.
2Quantity of substance
If Si-based material is used as anode active material to achieve high energy density, then battery capacity increases, but volume expansion during charging occurs, requiring additional jigs and reducing energy density
Solution Approach 1:
The patent converts the harmful effect of Si volume expansion into a beneficial feature by designing the anode layer with controlled voids that accommodate this expansion. The voids, which could be considered defects, are actually engineered features that allow the Si to expand and contract during charging-discharging cycles without causing battery swelling or requiring additional confining jigs. This transforms the expansion problem into a design advantage, maintaining high energy density while using Si-based materials.
3Quantity of substance
If the percentage of voids surrounded by solid electrolyte is optimized to balance swelling suppression and contact maintenance, then energy density is improved, but precise control of void distribution is required
Solution Approach 1:
The patent applies parameter changes by optimizing specific parameters of the voids (percentage range of 3.4-29.6 vol%, size distribution, and spatial arrangement) to achieve the desired balance between swelling suppression and contact maintenance. By defining specific parameter ranges rather than requiring exact values, the patent makes the manufacturing process more feasible while still achieving high energy density and low resistance.
Data Source
AI summary
An all-solid-state battery which includes an anode layer that contains a Si-based material as an anode active material and which has high energy density. Provided is an all-solid-state battery including a cathode layer, an anode layer, and a solid electrolyte layer disposed between the cathode layer and the anode layer, wherein the anode layer includes an anode active material that contains at least one Si-based material selected from the group consisting of Si and a Si alloy, and a solid electrolyte that contains a sulfide-based solid electrolyte; wherein a void surrounded by the solid electrolyte is present in at least a region formed by the solid electrolyte in the anode layer; and wherein, when a total volume of the anode layer is determined as 100 vol %, a percentage of the voids surrounded by the solid electrolyte in the anode layer, is 3.4 vol % or more and 29.6 vol % or less.