Tailoring the passivation layer on lithium metal anode and aluminum collector by regulating the solvation structure to enhance the long-term cycling of lithium metal batteries

Abstract

Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is widely employed in lithium metal batteries (LMB) owing to its capacity for efficiently mitigating the growth of lithium dendrites and enhancing the interface stability of lithium metal anodes. Unfortunately, LiTFSI frequently causes severe aluminum (Al) corrosion and leads to LMB failure. To address this issue, we conducted solvation structure design in the electrolyte using co-solvents such as 1,2-diethoxyethane, fluoroethylene carbonate and adiponitrile. Both experimental and computational evidences demonstrate that the co-solvents can regulate the solvation structure of electrolyte and promote the formation of more anion-rich internal solvation shells, ultimately enhancing the interfacial stability of Li anode and Al collector. When paired with high-loading LiFePO4 cathode, the full cell exhibits a long-term lifespan (1000 cycles) and outstanding capacity retention (86.4 %). Even the full cell with stringent conditions of NMC811 (∼4.0 mAh cm−2), 50 μm thin Li (N/P = 2.5) and the optimized electrolyte still enables to output over 110 cycles and 80.0 % capacity retention. This work provides an efficacious and innovative strategy to stabilize Li metal anode and Al current collector through solvation structure regulation.