Lithium-Ion Conduction Through Frozen Phase of Organic Electrolytes for Lithium Batteries.

Cheong, Do Sol; Kwon, Minjun; Jung, Pil-Su; Yoo, Seongmin; Hong, Jinki; Heo, Eun Seon; Lee, Jeongin; Choi, Yewon et al. · Adv Mater · 2026

basic_science · Level V

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Abstract

Organic ice electrolytes in their frozen states are presented as molecular-solid Li<sup>+</sup> conductors for lithium metal batteries (LMBs), challenging the notion that frozen electrolytes lack ionic conductivity. Ethylene carbonate, a cyclic carbonate, was predicted to form Li<sup>+</sup>-conductive channels in its frozen crystal structure. A room-temperature ice-phase electrolyte, EC<sub>0.2T</sub> (0.2 m LiTFSI in ethylene carbonate), exhibited a high ionic conductivity (∼0.64 mS cm<sup>-</sup> <sup>1</sup>) and a high Li<sup>+</sup> transference number (∼0.8) via hopping mechanism through solid matrix formed by immobilized solvent molecules. Frozen EC<sub>0.2T</sub> delivered liquid-electrolyte-level capacity in LFP||Li cells and, more importantly, significantly extended cycle life with a solvent-derived, Li<sub>2</sub>O-rich solid electrolyte interphase.