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-circuiting due to cracks in the solid electrolyte and high interfacial resistance between the anode and the solid electrolyte, which can lead to safety issues and reduced energy density.
Innovation Solution
Incorporating a thin contact layer of lithium metal or a lithium alloy between the anode active material layer and the solid electrolyte, with a thickness less than the anode active material layer, to minimize crack formation and reduce interfacial resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as anode active material to increase energy density, then specific capacity increases about 10 times compared to graphite, but cracks in solid electrolyte occur leading to short-circuit
Solution Approach 1:
A contact layer comprising a metal M is introduced as an intermediary between the lithium metal anode active material layer and the solid electrolyte. This contact layer prevents direct contact between lithium metal and solid electrolyte, thereby preventing crack formation in the solid electrolyte while maintaining the high specific capacity benefits of lithium metal. The metal M layer acts as a protective mediator that eliminates the harmful interaction between lithium and solid electrolyte.
2Object-affected harmful factors
If solid electrolyte is used instead of electrolyte solution to improve safety, then fire risk is reduced, but interfacial resistance between anode and solid electrolyte increases
Solution Approach 1:
The contact layer comprising metal M serves as an intermediary that reduces interfacial resistance between the anode and solid electrolyte. This thin metal layer improves electrical contact and ionic conductivity at the interface while preserving the safety advantages of the solid electrolyte system by maintaining the flammable-free environment.
3Reliability
If contact layer thickness is reduced to minimize crack formation, then solid electrolyte stability improves, but interfacial contact area decreases
Solution Approach 1:
The thickness of the contact layer comprising metal M is precisely controlled within the range of 1 nm to 100 nm. This parameter optimization ensures the contact layer is thin enough to prevent crack formation in the solid electrolyte while being sufficiently thick to maintain adequate interfacial contact area for electrical conductivity and ionic transport.
Data Source
AI summary
An all-solid secondary battery, including: a cathode; an anode; and a solid electrolyte disposed between the cathode and the anode, wherein the anode includes an anode current collector; a first anode active material layer in contact with the anode current collector and including a first metal; a second anode active material layer disposed between the first anode active material layer and the solid electrolyte and including a carbon-containing active material; and a contact layer between the second anode active material layer and the solid electrolyte, the contact layer including a second metal, and having a thickness less than a thickness of the first anode active material layer, wherein the second metal includes lithium metal, a lithium alloy, a metal alloyable with lithium, or a combination thereof.