LiDFOB Electrolyte for Lithium Metal Anode Dendrite Suppression
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Solution Overview
Problem
Lithium metal batteries face challenges such as high reactivity, unstable solid electrolyte interphase, dendrite growth, and volume changes, leading to short circuits, low columbic efficiency, and safety concerns due to the inherent properties of lithium metal anodes, which hinder their commercialization and performance compared to carbon-based anodes in lithium ion batteries.
Innovation Solution
A lithium metal battery design incorporating a lithium difluoro(oxalato)borate (LiDFOB) salt-based electrolyte with a solvent mixture comprising cyclic carbonates, linear esters or carbonates, and fluorinated esters, specifically fluoroethylene carbonate (FEC), ethyl methyl carbonate (EMC), and ethyl difluoroacetate, to stabilize the lithium metal anode during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal anode is used to increase energy density, then theoretical specific capacity is improved, but dendrite growth and short circuiting occur
Solution Approach 1:
A co-solvent comprising a linear carbonate and a linear ester is introduced as an intermediary between the lithium metal anode and the electrolyte. This co-solvent modifies the electrolyte composition to suppress dendrite growth while maintaining high specific capacity, acting as a mediator that resolves the contradiction between energy density and reliability
Solution Approach 2:
The electrolyte composition parameters are changed by incorporating specific ratios of linear carbonate and linear ester co-solvents. This parameter modification alters the electrochemical properties of the electrolyte to prevent dendrite formation, allowing the lithium metal anode to function reliably at high specific capacity
2Use of energy by moving object
If lithium metal anode is used to increase energy density, then cell-level energy is improved, but unstable solid electrolyte interphase is formed
Solution Approach 1:
The co-solvent mixture of linear carbonate and linear ester acts as an intermediary that stabilizes the solid electrolyte interphase formation. It modifies the interphase composition and structure, preventing instability while preserving the high energy density benefits of lithium metal anodes
Solution Approach 2:
The electrolyte is formulated as a composite system combining linear carbonate, linear ester, and lithium salt. This composite electrolyte composition creates a stable solid electrolyte interphase through synergistic interactions between components, resolving the stability issue while maintaining high cell-level energy
3Use of energy by moving object
If lithium metal anode is used to increase energy density, then specific capacity is improved, but high reactivity causes safety concerns
Solution Approach 1:
The co-solvent mixture serves as a protective intermediary between the highly reactive lithium metal anode and the electrolyte environment. It moderates the reactivity by forming a controlled interface, reducing harmful side reactions while preserving the high specific capacity of lithium metal
Solution Approach 2:
The electrolyte composition parameters are optimized by incorporating linear carbonate and linear ester in specific proportions. This parameter change reduces the effective reactivity of the lithium metal anode by altering the electrolyte's interaction characteristics, thereby improving safety while maintaining high specific capacity
4Productivity
If conventional electrolyte is used with lithium metal anode, then battery operation is achieved, but volume change during cycling reduces battery life
Solution Approach 1:
The electrolyte composition parameters are modified by adding linear carbonate and linear ester co-solvents. This parameter change accommodates the volume changes of lithium metal anode during cycling, reducing mechanical stress and extending battery life while maintaining operational performance
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 electrolyte formulation significantly enhances the cycling performance and capacity retention of lithium metal batteries, reducing the risk of dendrite formation and improving safety, thereby extending the battery life and maintaining high discharge capacity over multiple cycles.
Implementation Method 1
The electrolyte has lithium difluoro(oxalato)borate (LiDFOB) salt and a solvent mixture
Implementation Method 2
stabilize the lithium metal anode during cycling
Data Source
AI summary
A battery includes a cathode, a lithium metal anode, and an electrolyte. The electrolyte includes lithium difluoro(oxalato)borate (LiDFOB) salt and a solvent mixture. The solvent mixture includes a first organic solvent having a cyclic carbonate and a second organic solvent having a linear ester or a linear carbonate.