Electrolyte Intermolecular Interaction Mediated Nonflammable Potassium-Ion Sulfur Batteries
Honghong Liang, Pushpendra Kumar, Zheng Ma, Fei Zhao, Haoran Cheng, Hongliang Xie, Z. Cao, Luigi Cavallo, Qian Li, Jun Ming
Abstract
The design of electrolytes that are compatible with graphite electrodes and incorporate flame-retardant properties in potassium-ion batteries (PIBs) can not only facilitate their commercialization but also improve the safety reliability. However, it remains challenging, particularly in propylene carbonate (PC)-based electrolytes. Herein, we achieved a highly reversible K + (de)intercalation with graphite in PC-based electrolytes by introducing the fluoroethers. We identified the strength of interactions formed between fluoroethers (e.g., 1,1,2,2-tetrafluoroethy-2,2,3,3-tetrafluoropropyl ether (HFE), 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (TFTFE)) and PC by heteronuclear overhauser effect spectroscopy. We find that the interaction between HFE and PC is stronger, which can significantly weaken the K + -PC interaction, contributing to a reversible K + (de)intercalation and also endowing electrolyte nonflammable features. The kinetic and thermodynamic properties of K + -solvent-anion complexes in the proposed interfacial model can elucidate the electrolyte and electrode stability, enabling the as-designed potassium-ion sulfur batteries to show high performance. This discovery offers a fresh perspective for designing and advancing electrolytes in PIBs and beyond.