Chlorination Design for Carbonate-Based Electrolytes toward Advanced Lithium Metal Batteries

The pursuit of advanced lithium metal batteries (LMBs) is hindered by severe interfacial challenges, especially under high-rate cycling or elevated cutoff voltage conditions, which intensify lithium dendrite proliferation and parasitic electrolyte decomposition reactions between conventional carbonate electrolytes and the lithium metal anode (LMA). Here, we propose a chlorination design for traditional carbonate-based electrolytes by substituting chlorine (Cl) into dimethyl carbonate (DMC) and ethylene carbonate (EC) to form chloromethyl methyl carbonate (ClDMC) and 4-chloro-1,3-dioxolan-2-one (ClEC), which exhibit high-voltage resistance, weak solvating capability, and flame-retardant ability. The strategic introduction of Cl substituents disrupts Li+-solvent coordination, enabling rapid desolvation and spatially uniform Li deposition. Due to the electron-withdrawing characteristics of the Cl atom, the high-voltage stability of the chlorinated carbonates is also significantly enhanced. Consequently, under high cutoff voltages (4.3 and 4.5 V) and high cathode mass loading (10.5 mg cm–2) conditions, the Li|ClBE|NCM811 (LiNi0.8Co0.1Mn0.1O2) cells achieve 80 and 85% capacity retention after 350 and 150 cycles, respectively. Even under fast charging/discharging conditions (1 C/3 C), the Li/NCM811 cells with ClBE demonstrate stable cycling for 450 cycles with a capacity retention of 80%. This study provides impressive insight into the chlorination design for developing advanced electrolytes for high-voltage and fast-charging LMBs.