Silver-Additive Electrolyte for Stable Lithium Metal SEI
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Solution Overview
Problem
Lithium metal batteries face issues with rapid capacity degradation and low lifetime performance due to unstable solid electrolyte interphase (SEI) layer formation and side reactions between the electrolyte solution and lithium metal, leading to commercialization challenges.
Innovation Solution
An electrolyte solution containing a silver (Ag) compound additive, such as AgHFB, is used to form an Ag-based coating on the current collector and lithium metal, enhancing SEI layer stability and reducing lithium deposition overvoltage, thereby improving lithium ion reversibility and surface stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as the negative electrode to achieve high energy density, then the energy density per volume is improved, but the stability of the interface between current collector and lithium metal deteriorates, causing rapid capacity degradation and low lifetime performance
Solution Approach 1:
The patent introduces a Cu-based intermediate layer between the current collector and lithium metal. This intermediate layer acts as a mediator that promotes stable Li+ electrodeposition and prevents direct contact between the current collector and lithium metal, thereby improving interface stability while maintaining high energy density benefits
Solution Approach 2:
The patent modifies the surface properties of the current collector by applying a Cu-based coating with specific thickness (0.1-10 μm) and surface treatment parameters. This changes the electrodeposition characteristics from unstable to stable, enabling reliable lithium metal battery operation
2Ease of manufacture
If a pristine-Cu current collector is used that is not surface-treated, then the manufacturing simplicity is improved, but the lithium ion electrodeposition capability deteriorates, causing overvoltage
Solution Approach 1:
The patent applies a Cu-based surface treatment to the current collector before battery assembly. This preliminary action creates a surface that is optimized for Li+ electrodeposition, preventing overvoltage issues during battery operation while maintaining relatively simple manufacturing processes
3Quantity of substance
If high reactivity of lithium metal is utilized to achieve high capacity, then the battery capacity is improved, but the stability of the solid electrolyte interphase (SEI) layer deteriorates, accelerating side reactions between electrolyte solution and lithium metal
Solution Approach 1:
The Cu-based intermediate layer serves as a protective mediator between the lithium metal and the electrolyte solution. It stabilizes the SEI layer formation and prevents direct harmful interactions between the highly reactive lithium metal and the electrolyte, enabling high capacity utilization with improved stability
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 Ag-based coating suppresses side reactions, stabilizes the lithium metal interface, and enhances the lifespan and electrochemical performance of lithium secondary batteries, particularly under high positive electrode specific capacity conditions.
Implementation Method 1
a silver (Ag) compound additive... which together enhance the formation of a stable solid electrolyte interphase (SEI) layer, improve lithium ion reversibility, and reduce lithium deposition overvoltage
Implementation Method 2
improve lithium ion reversibility... lithium salt, a nonaqueous organic solvent, and a silver (Ag) compound additive
Data Source
AI summary
An electrolyte solution for a lithium secondary battery is provided, comprising a lithium salt, a nonaqueous organic solvent with at least 50% FSA by volume, and a silver (Ag) compound additive selected from AgHFB, AgPFP, or silver trifluoroacetate. The additive is present in an amount of about 0.05 wt % to 0.2 wt % to promote stable SEI layer formation and reduce lithium deposition overvoltage. The solution may also include a secondary additive such as calcium hydride (CaH2) or magnesium fluoride (MgF2) to further suppress lithium dendrite growth. The lithium secondary battery incorporating this electrolyte is designed to form a lithium metal layer with a thickness of 40 to 45 μm and a surface pore average diameter of less than 1 μm during the initial charging process, optimizing performance and stability.