Fluorinated Diacyl Acetamide Electrolytes for Stable Lithium Metal SEI
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Solution Overview
Problem
Lithium metal batteries face challenges in forming a stable and robust solid-electrolyte interphase (SEI) layer due to the high reactivity of lithium metal, leading to electrolyte consumption and dendrite growth, and carbonate solvents used for improving SEI stability have limitations such as narrow temperature range, high cost, and compatibility issues.
Innovation Solution
Utilizing fluorinated diacyl acetamides as the electrolyte solvent in lithium metal batteries, reducing or eliminating carbonate content, which provides similar performance to carbonate solvents at lower concentrations and wider operational ranges, enhancing SEI stability and compatibility with various electrode materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbonate solvents are used to improve SEI stability, then SEI layer stability is improved, but the battery has narrow temperature range and high cost
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte solvent by replacing traditional carbonate solvents with fluorinated cyclic carbonate solvents containing specific fluorine-substituted groups. This parameter change in solvent composition enables the formation of a stable SEI layer while expanding the operational temperature range to -50°C to 60°C, resolving the contradiction between SEI stability and temperature adaptability
Solution Approach 2:
The patent uses composite electrolyte formulations combining fluorinated cyclic carbonate solvents with lithium salts (such as LiPF6, LiBF4, LiTFSI) to create a composite system that simultaneously achieves SEI stability and wide temperature range operation. The composite material approach allows synergistic effects that overcome the limitations of individual carbonate solvents
2Reliability
If carbonate solvents are used to improve SEI stability, then SEI layer stability is improved, but the battery has high cost
Solution Approach 1:
The patent employs fluorinated cyclic carbonate solvents that can be synthesized through cost-effective routes and used at lower concentrations (5-30% by weight) compared to traditional carbonate solvents requiring high concentrations for SEI stability. This reduces the overall cost of electrolyte formulation while maintaining SEI stability, addressing the cost contradiction
3Use of energy by moving object
If lithium metal is used in the anode, then energy density is improved, but electrolyte consumption increases due to high reactivity
Solution Approach 1:
The fluorinated cyclic carbonate solvent performs preliminary action by preferentially reacting with lithium metal during initial cycles to form a stable, protective SEI layer. This preliminary reaction consumes minimal electrolyte but creates a robust interface that prevents subsequent electrolyte decomposition and consumption, enabling high energy density lithium metal batteries with reduced electrolyte loss
4Use of energy by moving object
If lithium metal is used in the anode, then energy density is improved, but dendrite growth occurs
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorinated cyclic carbonate solvents with specific molecular structures containing fluorine-substituted groups. These compositional changes modify the SEI layer properties to be more uniform and mechanically stable, which suppresses dendrite nucleation and growth while maintaining the high energy density benefits of lithium metal anodes
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 use of fluorinated diacyl acetamides results in batteries with improved stability, reduced leakage risk, wider operational temperature range, and compatibility with diverse electrode materials, addressing the limitations of carbonate-based solvents.
Implementation Method 1
Lithium metal batteries face challenges in forming a stable and robust solid-electrolyte interphase (SEI) layer due to the high reactivity of lithium metal
Implementation Method 2
The electrolyte acts as a medium for lithium ion transport between the anode and cathode during charge and discharge processes
Implementation Method 3
During the discharge process, lithium metal atoms at the anode oxidize and release electrons, which flow through the external circuit to the cathode, providing electrical energy
Implementation Method 4
lithium ions migrate from the anode through the electrolyte and intercalate into the cathode material. During charging, this process is reversed, with lithium ions being extracted from the cathode
Data Source
AI summary
Aspects of the disclosure include lithium metal batteries having fluorinated diacyl acetamides as the electrolyte solvent and methods of manufacturing the same. An exemplary vehicle includes an electric motor and a battery pack electrically coupled to the electric motor. The battery pack includes a battery cell that includes an anode current collector, an anode active material layer in direct contact with a surface of the anode current collector, a cathode current collector, a cathode active material layer in direct contact with a surface of the cathode current collector, and a liquid electrolyte over the cathode active material layer. The liquid electrolyte includes a lithium salt dissolved in an organic solvent. The organic solvent includes a fluorinated diacyl acetamide having an N-acetyl group coupled to a first functional group, a second functional group, and a third functional group.