Hard-Coated Negative Electrode for Uniform Lithium Plating
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Solution Overview
Problem
Lithium ion batteries using liquid electrolytes are prone to overheating and fire due to combustible organic solvents, posing safety risks, while solid-state batteries with solid electrolytes are needed to mitigate these risks but face issues with non-uniform lithium plating leading to micro-cracks and short circuits.
Innovation Solution
A negative electrode structure featuring a first metal substrate coated with a second metal layer having higher Mohs hardness than the substrate, which prevents irregularities and enhances uniformity of lithium plating, thereby reducing micro-cracks in the solid electrolyte layer and minimizing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid-state battery uses a solid electrolyte layer, then safety is improved by eliminating combustible organic solvents, but non-uniform lithium plating occurs leading to micro-cracks and short circuits
Solution Approach 1:
A coating layer comprising silicon oxide or silicon oxynitride is introduced as an intermediary between the negative electrode active material layer and the solid electrolyte layer. This coating layer acts as a mediator that promotes uniform lithium ion distribution and plating, preventing direct harmful interactions while maintaining the safety benefits of the solid electrolyte.
Solution Approach 2:
The invention applies a specific coating layer with distinct chemical composition (silicon oxide or silicon oxynitride) only at the interface between the negative electrode active material layer and the solid electrolyte layer. This localized treatment addresses the plating uniformity issue at the critical interface region without affecting other parts of the battery structure.
2Ease of manufacture
If lithium ion batteries use liquid electrolytes, then ease of manufacture is maintained, but safety deteriorates due to overheating and fire risks from combustible organic solvents
Solution Approach 1:
The invention changes the physical state parameter of the electrolyte from liquid to solid, eliminating the combustibility issue while maintaining battery functionality. The solid electrolyte layer provides inherent safety by removing organic solvents, and the additional coating layer ensures manufacturability by preventing defects that would arise from non-uniform plating.
3Manufacturing precision
If a coating layer with higher Mohs hardness than the metal substrate is used, then manufacturing precision of lithium plating is improved, but device complexity increases
Solution Approach 1:
The invention creates a composite structure consisting of the negative electrode active material layer, the silicon oxide or silicon oxynitride coating layer, and the solid electrolyte layer. This composite material approach achieves uniform lithium plating through the specific properties of the coating layer while maintaining overall structural simplicity suitable for manufacturing.
Data Source
AI summary
A negative electrode includes a negative electrode current collector and a first negative electrode active material layer on the negative electrode current collector, wherein the negative electrode current collector includes a first metal substrate including a first metal, and a coating layer positioned on the first metal substrate and containing a second metal, the second metal having a greater Mohs hardness than the first metal.