Entropy-Driven Hybrid Gel Electrolyte Enables Practical High-Voltage Lithium Metal Batteries

Abstract

Electrolyte engineering plays a crucial role in enhancing the performance of lithium metal batteries (LMBs) featuring high-voltage cathodes and limited lithium anodes, thereby unlocking their potential for high-energy electrochemical storage. Herein, an entropy-driven hybrid gel electrolyte with enhanced diversity in Li-ion solvation structures is designed by incorporating substantial amounts of insoluble LiPO 2 F 2 and LiNO 3 salts into LiPF 6 -based carbonate electrolytes, followed by in situ thermal polymerization. Specifically, the Li + solvation structures are modulated via ionophilic NO 3 − and PO 2 F 2 − to generate an anion-rich solvation sheath and thus promote anion reduction at the electrode−electrolyte interface. The interfaces enriched in anion-derived inorganic components facilitate rapid ionic transport, thus enabling smooth and dense Li morphology and ultimately enhancing the electrochemical performance of LMBs. As a result, this high-hybrid gel electrolyte confers LMBs employing high-voltage NCM cathodes, as demonstrated by sustained performance in both coin-cell (500 cycles at 4.5 V) and Ah-level pouch cell configurations under practical conditions (60 cycles, N/P: 1.92, and E/C: 2.0 g Ah −1 ).