Fluorinated Glycol Ether Electrolytes for High-Voltage Li-Ion Cells
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Solution Overview
Problem
Lithium-ion batteries using organosulfur electrolytes face high viscosity and polarization issues due to the non-solvating nature of conventional fluorinated ethers, which reduces conductivity and anodic stability.
Innovation Solution
Incorporating a terminally fluorinated glycol ether as a co-solvent in organosulfur electrolytes enhances anodic stability and conductivity by forming a robust solid-electrolyte interphase, allowing for stable high-voltage cycling of lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluorinated ethers are used as solvents in organosulfur electrolytes, then anodic stability is improved, but conductivity deteriorates due to high viscosity and non-solvating nature
Solution Approach 1:
The patent combines conventional fluorinated ethers with terminally fluorinated glycol ethers to create a composite electrolyte system. The fluorinated glycol ether component (Formula I) introduces solvating capability through its ether oxygen atoms while maintaining the fluorinated chain's anodic stability. This composite approach allows the electrolyte to simultaneously achieve high conductivity through effective Li salt solvation and high anodic stability through the fluorinated structure.
Solution Approach 2:
The invention modifies the molecular structure parameters of the fluorinated ether by introducing hydroxyl groups at terminal positions and creating glycol ether linkages. These structural parameter changes enable the molecule to form hydrogen bonds and effectively solvate lithium salts, transforming the non-solvating conventional fluorinated ether into a solvating electrolyte component with improved conductivity while retaining anodic stability.
2Reliability
If organosulfur electrolytes are used in lithium-ion batteries, then safety is improved, but polarization increases due to high viscosity
Solution Approach 1:
The patent creates a composite electrolyte system combining organosulfur compounds with terminally fluorinated glycol ethers. The glycol ether component reduces the overall viscosity of the electrolyte mixture through its molecular structure and hydrogen bonding capability, thereby reducing polarization effects. Meanwhile, the organosulfur component maintains the inherent safety advantages, creating a synergistic electrolyte system that achieves both low polarization and high safety.
3Reliability
If conventional fluorinated ethers are used, then anodic stability is improved, but solvating capability deteriorates
Solution Approach 1:
The invention fundamentally changes the molecular parameters of fluorinated ethers by introducing terminal hydroxyl groups and glycol ether linkages. These parameter changes create hydrogen bonding sites and polar regions that enable effective solvation of lithium salts. The fluorinated alkyl chains are retained to preserve anodic stability, while the modified central structure provides solvating capability through oxygen atoms and hydrogen bonding networks.
Solution Approach 2:
The terminally fluorinated glycol ether acts as an intermediary molecule that bridges the gap between the fluorinated ether's anodic stability and the need for solvating capability. Its molecular structure contains both fluorinated regions (providing stability) and hydroxyl/glycol ether regions (providing solvation), effectively mediating between these two opposing requirements in the electrolyte system.
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 glycol ethers in organosulfur electrolytes significantly improves the conductivity and stability of lithium-ion batteries, enabling exceptional cycling performance and capacity retention.
Implementation Method 1
Incorporating a terminally fluorinated glycol ether as a co-solvent in organosulfur electrolytes enhances anodic stability and conductivity by forming a robust solid-electrolyte interphase
Implementation Method 2
the use of fluorinated glycol ethers in organosulfur electrolytes significantly improves the conductivity and stability of lithium-ion batteries
Data Source
AI summary
An electrochemical cell includes a cathode comprising a cathode active material, an anode comprising an anode active material, and an electrolyte comprising a sulfonyl solvent, a terminally fluorinated glycol ether, and a salt. Other electrochemical cells include a cathode, an anode, a separator, and an electrolyte comprising: a lithium salt; a cathode stabilizing additive selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, LiBF2(C2O4), LiB(C2O4)2, LiPF2(C2O4)2, LiPF4(C2O4), LiPF6, LiAsF6, CsF, CsPF6, Li2(B12X12-iHi), Li2(B10X10-i′Hi′), or a mixture of any two or more thereof, wherein the cathode stabilizing additive is not the same as the lithium salt, wherein each X is independently at each occurrence a halogen, i is an integer from 0 to 12 and i′ is an integer from 0 to 10; and a fluorinated organosulfate compound.