All-solid-state lithium ion battery anode surface area control
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Solution Overview
Problem
All-solid-state lithium ion secondary batteries using alloy-based anode active materials exhibit low capacity retention rates due to aggregation of anode active material particles, which disrupts the electron conducting path and leads to poor cycle characteristics.
Innovation Solution
Incorporating anode active material particles with a BET specific surface area of 1.9 m2/g to 14.2 m2/g, combined with an electroconductive material and a solid electrolyte, ensures stable contact and maintains both electron and ion conductivity, thereby enhancing cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alloy-based active material particles are used as anode active material, then theoretical capacity per volume is increased, but capacity retention rate deteriorates due to particle aggregation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the BET specific surface area of anode active material particles within the range of 1.9 m2/g to 14.2 m2/g. This parameter optimization prevents particle aggregation while maintaining high theoretical capacity, thereby improving capacity retention rate during charge-discharge cycles
Solution Approach 2:
The patent uses composite materials by combining alloy-based active material particles with a solid electrolyte and electroconductive material in specific volume ratios. The solid electrolyte content is controlled at 30-70 vol% and electroconductive material at 5-20 vol%, creating a composite structure that maintains particle dispersion and prevents aggregation, thus improving capacity retention
2Reliability
If anode active material particles with high surface area are used, then electron conducting path is improved, but particle aggregation occurs disrupting the conducting path
Solution Approach 1:
The patent optimizes the BET specific surface area parameter to 1.9-14.2 m2/g, which provides sufficient surface area for electron conduction while preventing excessive surface area that would cause particle aggregation. This balanced parameter ensures stable particle dispersion and maintains electron conducting path integrity
Solution Approach 2:
The solid electrolyte acts as an intermediary material between anode active material particles, preventing direct particle-to-particle contact that causes aggregation. The solid electrolyte content of 30-70 vol% ensures particles remain dispersed while maintaining electron and ion conductivity through the composite structure
Data Source
AI summary
Disclosed is an all-solid-state lithium ion secondary battery excellent in cycle characteristics. The battery may be an all-solid-state lithium ion secondary battery, wherein an anode comprises anode active material particles, an electroconductive material and a solid electrolyte; wherein the anode active material particles comprise at least one active material selected from the group consisting of elemental silicon and SiO; and wherein a BET specific surface area of the anode active material particles is 1.9 m2/g or more and 14.2 m2/g or less.