Solid-State Battery Anode Contact Layer for Crack-Free Interfaces
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Solution Overview
Problem
All-solid secondary batteries face challenges with short-circuit occurrences due to cracks in the solid electrolyte, which can lead to safety issues and reduced energy density, especially when lithium is used as an anode active material.
Innovation Solution
Incorporating a thin contact layer with a metal, such as lithium or a lithium alloy, between the anode active material layer and the solid electrolyte layer to minimize crack formation and interfacial resistance, while using a carbon-containing active material in the second anode layer to alleviate volume changes and prevent direct contact with the solid electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium is used as anode active material to increase energy density, then capacity density increases about 10 times compared to graphite, but cracks in solid electrolyte occur leading to short-circuits
Solution Approach 1:
A contact layer comprising a metal is introduced as an intermediary between the anode active material layer (lithium) and the solid electrolyte layer. This contact layer prevents direct contact between lithium and solid electrolyte, thereby preventing crack formation in the solid electrolyte while maintaining the high capacity density benefit of lithium anode.
2Object-affected harmful factors
If solid electrolyte is used instead of electrolytic solution to improve safety, then fire risk is reduced, but cracks in solid electrolyte cause short-circuits
Solution Approach 1:
The contact layer serves as a protective intermediary that prevents mechanical cracks from forming in the solid electrolyte during charge/discharge cycles. This maintains the intrinsic safety advantage of solid electrolyte (no fire risk) while eliminating the reliability issue of crack-induced short-circuits.
3Reliability
If contact layer is added between anode and solid electrolyte to prevent cracks, then short-circuit likelihood decreases, but interfacial resistance increases
Solution Approach 1:
The thickness of the contact layer is precisely controlled to be between 1 nm and 1 μm. This parameter optimization ensures that the contact layer is thick enough to prevent cracks and provide mechanical protection, yet thin enough to minimize interfacial resistance and maintain good electrical contact between the anode and solid electrolyte.
Data Source
AI summary
An all-solid secondary battery, including: a cathode; an anode; and a solid electrolyte layer disposed between the cathode and the anode, wherein the anode comprises an anode current collector; a first anode active material layer in contact with the anode current collector and comprising a first metal; a second anode active material layer disposed between the first anode active material layer and the solid electrolyte layer and comprising a carbon-containing active material; and a contact layer between the second anode active material layer and the solid electrolyte layer, and disposed such that the contact layer prevents contact between the second anode active material layer and the solid electrolyte layer, wherein the contact layer comprises a second metal, and has a thickness less than a thickness of the first anode active material layer.