Fluorinated Ether Electrolytes for Lithium Metal and High-Voltage Cathodes
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Solution Overview
Problem
Existing electrolyte formulations for lithium ion batteries are incompatible with lithium metal anodes, leading to low coulombic efficiency and lithium dendrite formation due to undesired side reactions, and are prone to oxidation at high-voltage cathodes, limiting the design of compatible electrolytes for high-performance lithium batteries.
Innovation Solution
Halogenated ether compounds with strategically placed fluorine functional groups that form robust solid electrolyte interphases (SEIs), reducing anode-electrolyte reactions, stabilizing the ethereal oxygen, and suppressing oxidation at cathodes, while maintaining compatibility with lithium anodes and high-voltage cathodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ether-based electrolytes are used to suppress lithium dendrite formation, then anode stability is improved, but cathode oxidation resistance deteriorates at high-voltage cathodes
Solution Approach 1:
The patent introduces fluorine substitution at specific positions of the ether molecule (alpha or beta positions relative to oxygen) to create local regions with different electronic properties. The fluorine atoms provide electron-withdrawing effects that stabilize the ether oxygen against oxidation at the cathode, while the rest of the ether structure maintains its ability to form protective SEI at the anode. This localized modification resolves the contradiction between anode stability and cathode oxidation resistance.
Solution Approach 2:
The patent changes the electrochemical parameters of the ether electrolyte by introducing fluorine substituents. The fluorine atoms alter the HOMO energy level and oxidation potential of the ether, raising the oxidation potential to match high-voltage cathodes. Simultaneously, the fluorine-containing groups participate in forming stable SEI at the anode. This parameter change enables the electrolyte to withstand both anode reduction and cathode oxidation.
2Reliability
If conventional electrolyte formulations are used, then lithium ion battery performance is maintained, but compatibility with lithium metal anodes deteriorates due to low coulombic efficiency and dendrite formation
Solution Approach 1:
The fluorinated ether compounds perform preliminary action by forming stable protective SEI layers at the lithium metal anode surface before significant parasitic reactions occur. The fluorine-containing groups preferentially react with lithium ions to create a stable interface that prevents subsequent dendrite formation and electrolyte decomposition, thereby improving coulombic efficiency and anode compatibility.
Solution Approach 2:
The patent creates a composite interface structure at the anode consisting of fluorinated ether-derived SEI components. The fluorine-substituted ether molecules form a composite protective layer that combines the benefits of ether-based SEI (flexibility, ion conductivity) with the stability of fluorine-containing compounds (low reactivity, high mechanical strength), resulting in improved anode compatibility and coulombic efficiency.
3Object-affected harmful factors
If fluorine functional groups are added to stabilize ethereal oxygen against oxidation, then cathode compatibility is improved, but excessive fluorination may result in sluggish transport or insolubility of salts
Solution Approach 1:
The patent applies fluorine substitution locally at specific positions (alpha or beta positions) rather than exhaustive fluorination. This localized approach provides sufficient electron-withdrawing effect to stabilize the ether oxygen against oxidation at high-voltage cathodes, while leaving other parts of the molecule with adequate solubility and transport properties. The selective positioning of fluorine atoms balances oxidation resistance with salt solubility.
Solution Approach 2:
The patent employs partial fluorination rather than complete fluorination of the ether molecule. By introducing fluorine atoms at optimal positions and quantities (mono-, di-, or trifluorinated derivatives), the patent achieves sufficient oxidation protection without over-fluorinating to the point of compromising salt solubility or ion transport. This partial action approach optimizes the balance between stability and reactivity.
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 halogenated ether compounds enhance coulombic efficiency, prevent lithium dendrite formation, and maintain stability at both anodes and cathodes, enabling the development of high-performance lithium batteries with improved electrochemical stability and durability.
Implementation Method 1
it is beneficial to form a protective solid electrolyte interphase (SEI) that can inhibit reaction between the anode and the electrolyte components
Implementation Method 2
fluorine functional groups can weaken the solvation ability of the solvent and provide stronger Li-ion/anion interaction in the electrolyte
Implementation Method 3
the strong electron-withdrawing ability of the fluorine functional groups can stabilize the ethereal oxygen found in these compounds, thus preventing it from undergoing oxidation at high-voltage cathodes
Data Source
AI summary
Provided herein are halogenated ether compounds of Formula (I), Formula (II), or Formula (III):Also provided are electrolytes comprising one or more compounds of Formula (I), Formula (II), or Formula (III) and electrochemical cells comprising electrolytes comprising one or more compounds of Formula (I), Formula (II), or Formula (III).