Oscillating lithium ion-acceptor fluorine-donor electrolytes for practical fast-charging high-energy lithium metal pouch cells

• Published in: Energy & environmental science Vol. 18; no. 12; pp. 6224 - 6236
• Main Authors: Ruan, Digen, Wang, Yanru, Guo, Jiasen, Cui, Zhuangzhuang, Nian, Qingshun, Ma, Zhihao, Wang, Dazhuang, Fan, Jiajia, Ma, Jun, Xiong, Bingqing, Dong, Qi, Cao, Ruiguo, Jiao, Shuhong, Ren, Xiaodi
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 17.06.2025
• Subjects: Charging; Electrolytes; Electrolytic cells; Energy storage; Ethane; Fluorine; High voltages; Lithium; Lithium batteries; Lithium ions; Lithium oxides; Solvation; Voltage
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d5ee00227c

High-voltage Li metal batteries (LMBs) are promising high-energy-density energy storage solutions. However, achieving fast-charging under practical conditions has been a formidable challenge. Here, we synthesized 2-fluoro-1,1-dimethoxy-ethane (FDMN) with a super-lithiophilic fluorine group as a strategical co-solvent to address the long-standing dilemma between rapid Li + transport in bulk electrolytes and stable electrode-electrolyte interphases. As a Li + acceptor, FDMN shows a unique oscillating feature to enable fast Li + exchange across solvation complexes due to the asymmetric polar fluorine site, achieving a high Li + transference number of 0.80. As a fluorine donor, the strong fluorine-donating ability of FDMN facilitates the formation of an amorphous inorganic SEI interlaced with nanocrystalline Li 2 O on the Li metal anode and a LiF-rich CEI on the high-voltage cathode. FDMN-based electrolytes improve Li coulombic efficiency under high current densities and enable excellent 1C/2C fast-cycling for 4.5 V nickel-rich LMBs with inhibited Li dendrite growth and Li consumption. Significantly, for the first time, a practical 2 A h NMC811|Li pouch cell (412 W h kg −1 energy density based on the total mass) with a lean electrolyte (1.5 g A h −1 ) achieves over 120 stable cycles under 1C fast-charging and 2C fast-discharging. This electrolyte design principle presents an encouraging approach for realizing practical fast-charging high-energy-density LMBs. An oscillating Li + -acceptor fluorine-donor electrolyte incorporating a new co-solvent with an asymmetric super-lithiophilic fluorine group resolves the dilemma between fast electrolyte Li + transport and stable interphases.