Minimizing Solvent-Coordination in Ether Electrolytes for Lithium Metal Batteries under Extreme Operating Conditions.
basic_science · Level V
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- Record sourced from PubMed, PMID 40545822.
- Also identified by DOI 10.1002/adma.202505892.
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Abstract
Ether-based electrolytes are considered to be one of the most promising systems for high-performing lithium metal batteries (LMBs). However, the poor oxidation stability (<4.5 V) of ether solvents seriously limit their practical applications. Herein, high-voltage LMBs with LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub> (NCM811) cathode operated under extreme conditions by minimizing solvent-coordination in ether electrolytes with fluoroethers, nitrile ethers, and highly fluorinated additives, are demonstrated. It is revealed that ethylene glycol bis(propionitrile) ether (DENE) inhibits the lone-pair electrons loss on ether oxygen through strongly electron-withdrawing cyano groups to increase the electrochemical window to ≥5 V. Heptafluorobutyric anhydride (HFAA) triggers the formation of solid electrolyte interphase rich-in LiF-species, ensuring uniform deposition/stripping and high reversibility of Li<sup>+</sup>. Especially, DENE and HFAA synergistically minimizes the coordination number of ethylene glycol dimethyl ether (DME) and hexafluorophosphate (PF<sub>6</sub> <sup>-</sup>), thereby promoting the desolvation process of Li<sup>+</sup> and inhibiting the interfacial side reactions. Therefore, the NCM811 cathodes using modified electrolytes exhibit excellent electrochemical performance at ultrahigh voltage (4.7 V), ultrahigh rate (20 C), and ultrawide temperature range (-30 to 120 °C), and achieve stable operation in a high-capacity Li metal pouch cell of 30 Ah and a high-energy density Li metal pouch cell of 502.7 Wh kg<sup>-1</sup>, respectively.