Fluorinated Electrolyte Composition for Lithium Anode Dendrite Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion electrochemical cells with metallic lithium anodes suffer from poor cyclability due to dendrite growth, leading to short circuits and irreversible failure, and existing solutions like thick separators increase internal resistance and reduce power performance.
Innovation Solution
An electrochemical cell design featuring a metallic lithium or lithium alloy anode with a solvent composition of 1,1,1,3,3,3-hexafluoro-2-methoxypropane and ethylene monofluorocarbonate, along with lithium difluorophosphate, which enhances cyclability and safety by preventing dendrite growth and reducing internal pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a metallic lithium anode is used to increase capacity, then the cell capacity increases significantly, but lithium dendrites form during cycling causing short circuits and cell failure
Solution Approach 1:
A fluorinated solvent mixture (HFMP, F1EC, F3EMC or F3EA) acts as an intermediary between the metallic lithium anode and the electrolyte, forming a stable protective interface layer that prevents dendrite growth while allowing lithium ion transport, thus maintaining both high capacity and cyclability
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte by introducing fluorinated solvents with specific molecular structures (HFMP, F1EC, F3EMC, F3EA) that have different electrochemical properties compared to conventional carbonates, leading to improved dendrite resistance and cell stability
2Reliability
If a thick separator is used to prevent dendrite piercing, then dendrite resistance improves, but internal resistance increases and power performance drops
Solution Approach 1:
The fluorinated solvent mixture serves as a chemical intermediary that modifies the electrode-electrolyte interface, creating a protective layer that provides dendrite resistance without requiring a thick physical separator, thus maintaining low internal resistance and high power performance
3Ease of operation
If conventional carbonate solvents are used in the electrolyte, then the cell can operate, but lithium dendrites grow during cycling leading to short circuits
Solution Approach 1:
The invention changes the electrolyte composition by replacing conventional carbonate solvents with a specific mixture of fluorinated solvents (HFMP, F1EC, F3EMC or F3EA), which have different electrochemical stability and solvation properties that prevent dendrite formation while maintaining cell operability
Solution Approach 2:
The electrolyte is formulated as a composite system combining fluorinated solvents (HFMP, F1EC, F3EMC or F3EA) with lithium salts (LiPF6, LiBF4, LiTFM) and optional additives, creating a multi-component system that provides both operational ease and improved cyclability
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 solution extends the service life of lithium-ion cells under high-temperature cycling conditions, maintains capacity retention, and reduces the risk of ignition, thereby improving power performance and safety.
Implementation Method 1
a liquid or gelled electrolyte composition comprising: a) a solvent comprising: i) either a mixture of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMP) and/or 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), ethylene monofluorocarbonate (F1EC) and 2,2,2-trifluoroethyl methyl carbonate (F3EMC),
Implementation Method 2
at least one salt whose cation is the lithium cation
Data Source
AI summary
The invention relates to an electrochemical cell comprising: —at least one anode comprising metallic lithium or a lithium alloy or at least one anode comprising a current collector at least partially covered with metallic lithium deposited after at least one charge of the cell, the cell not containing metallic lithium at the time of its manufacture, —at least one cathode, - a liquid or gelled electrolyte composition comprising: a) a solvent comprising: i) either a mixture of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMP) and/or 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFMFP), ethylene monofluorocarbonate (F1EC) and 2,2,2-trifluoroethyl methyl carbonate (F3EMC), ii) or a mixture of 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMP) and/or 1,1,1,3,3,3-hexafluo-ro-2-(fluoromethoxy)propane (HFMFP), ethylene monofluorocarbonate (F1EC) and 2,2,2-trifluoroethyl acetate (F3EA), b) at least one salt whose cation is the lithium cation, c) lithium difluorophosphate LiPO2F2 in an amount representing from 0.05 to 5% of the mass of the combination made up of the solvent and said at least one dissolved lithium salt.