Active Diluent‐Anion Synergy Strategy Regulating Nonflammable Electrolytes for High‐Efficiency Li Metal Batteries

• Published in: Angewandte Chemie International Edition 2024-02, Vol.63 (7), p.e202317176-n/a
• Main Authors: He, Ran, Deng, Kuirong, Mo, Daize, Guan, Xiongcong, Hu, Yuanyuan, Yang, Kai, Yan, Zhenhua, Xie, Haijiao
• Format: Article
• Language: English
• Subjects: Anions; Anodes; Cathodes; Compatibility; Copper; Cycles; Dimethyl acetamide; Electrolytes; Electrolytic cells; Energy storage; Flame Retardant; High voltages; Interface stability; Interphase; Li Metal Anodes; Li Metal Batteries; Lithium batteries; Lithium fluoride; Localized High Concentration Electrolytes; Metals; Solid Electrolyte Interphase; Solid electrolytes; Storage systems; Voltage
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202317176

High‐energy Li metal batteries (LMBs) consisting of Li metal anodes and high‐voltage cathodes are promising candidates of the next generation energy‐storage systems owing to their ultrahigh energy density. However, it is still challenging to develop high‐voltage nonflammable electrolytes with superior anode and cathode compatibility for LMBs. Here, we propose an active diluent‐anion synergy strategy to achieve outstanding compatibility with Li metal anodes and high‐voltage cathodes by using 1,2‐difluorobenzene (DFB) with high activity for yielding LiF as an active diluent to regulate nonflammable dimethylacetamide (DMAC)‐based localized high concentration electrolyte (LHCE‐DFB). DFB and bis(fluorosulfonyl)imide (FSI−) anion cooperate to construct robust LiF‐rich solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI), which effectively stabilize DMAC from intrinsic reactions with Li metal anode and enhance the interfacial stability of the Li metal anodes and LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes. LHCE‐DFB enables ultrahigh Coulombic efficiency (98.7 %), dendrite‐free, extremely stable and long‐term cycling of Li metal anodes in Li || Cu cells and Li || Li cells. The fabricated NCM811 || Li cells with LHCE‐DFB display remarkably enhanced long‐term cycling stability and excellent rate capability. This work provides a promising active diluent‐anion synergy strategy for designing high‐voltage electrolytes for high‐energy batteries. Nonflammable dimethylacetamide (DMAC)‐based localized high concentration electrolyte (LHCE‐DFB) was regulated by functional diluent 1,2‐difluorobenzene (DFB) via active diluent‐anion synergy strategy. DFB can cooperate with FSI− anion to construct robust LiF‐rich SEI and CEI owing to its good fluorine‐donating activity and low LUMO, effectively enhancing the interfacial stability of the Li metal anodes and LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes.