Solid State Battery Liquid Metal Interface Layer
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Solution Overview
Problem
Solid state batteries face degradation due to mechanical stresses at the lithium metal anode/solid electrolyte interface during cycling, leading to non-uniform plating and stripping of lithium, which results in reduced performance and increased resistance.
Innovation Solution
A method involving the formation of a eutectic liquid metal interface layer between the lithium anode and solid electrolyte by reacting a sacrificial layer with a metal alloy, using materials like galinstan or alloys of gallium, indium, and tin, to enhance adhesion and maintain contact area over multiple cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lithium metal anode is used in a solid state battery, then high energy density is achieved, but mechanical stresses at the interface during cycling cause degradation and non-uniform plating/stripping
Solution Approach 1:
The patent introduces a liquid metal interface layer (LMIL) as an intermediary between the lithium metal anode and solid electrolyte. This LMIL, composed of eutectic alloying elements (Ga, In, Sn), acts as a mediator that accommodates volume changes and maintains uniform contact during lithium plating and stripping cycles, preventing direct mechanical stress at the Li/SOLID electrolyte interface while preserving high energy density benefits
Solution Approach 2:
The patent changes the physical state parameter of the interface layer from solid to liquid by using a eutectic alloy composition (Ga-In-Sn) with melting point below room temperature. This liquid state allows the interface layer to dynamically adapt to volume changes during cycling, maintaining reliable electrical contact and preventing degradation while supporting high energy density operation
2Device complexity
If the solid electrolyte surface is directly contacted with the lithium anode, then device complexity is reduced, but adhesion deteriorates and contact area decreases over cycles
Solution Approach 1:
The patent inserts a liquid metal interface layer as an intermediary between the solid electrolyte and lithium anode. Although this adds a layer to the interface structure, the LMIL's liquid nature enables it to flow and conform to surface irregularities, creating superior adhesion and maintaining stable contact area over thousands of cycles, thereby improving reliability despite increased structural complexity
Solution Approach 2:
The patent creates a composite interface structure consisting of the solid electrolyte, liquid metal eutectic alloy layer, and lithium metal anode. This composite structure combines the benefits of each material: the solid electrolyte provides ionic conductivity, the liquid metal layer provides mechanical compliance and adhesion, and the lithium anode provides high capacity, resulting in improved overall interface reliability
3Duration of action of moving object
If cycling continues over thousands of cycles, then battery duration is extended, but mechanical stresses cause non-uniform plating and stripping leading to performance degradation
Solution Approach 1:
The liquid metal interface layer serves as a mediator that maintains uniform lithium distribution during extended cycling. Its liquid state allows it to continuously adapt to volume changes during plating and stripping, preventing the formation of dendrites and ensuring uniform lithium deposition, thereby maintaining performance consistency over thousands of cycles
Solution Approach 2:
The patent employs a dynamic interface layer that changes its physical state and composition during operation. The liquid metal LMIL dynamically adjusts its morphology and wetting properties during each charge-discharge cycle, allowing it to accommodate volume expansion and contraction of the lithium anode, thereby maintaining reliable electrical contact and uniform plating/stripping behavior over extended cycling duration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The eutectic liquid metal interface layer improves the stability and adhesion between the anode and electrolyte, maintaining contact area over thousands of cycles and enhancing the battery's performance by reducing resistance and degradation.
Implementation Method 1
contacting a metal alloy with the sacrificial layer such that the sacrificial layer and the metal alloy react to form a eutectic liquid metal interface layer, at room temperature
Implementation Method 2
The lithium anode is configured to alloy with the eutectic liquid metal interface layer at operating potential
Implementation Method 3
The eutectic liquid metal interface layer improves the stability and adhesion between the anode and electrolyte, maintaining contact area over thousands of cycles
Data Source
AI summary
A method of producing a solid state battery includes pre-coating a solid electrolyte surface with a metal to form a sacrificial layer and contacting a metal alloy with the sacrificial layer such that the sacrificial layer and the metal alloy react to form a eutectic liquid metal interface layer, at room temperature and between the electrolyte and a lithium anode, configured to alloy with the liquid metal interface layer at operating potential.