Forming Robust and Highly Li‐Ion Conductive Interfaces in High‐Performance Lithium Metal Batteries Using Chloroethylene Carbonate Additive

Developing high‐rate Li metal batteries (LMBs) is challenging because of dendrite growth and irreversible parasitic reactions of the Li metal. Herein, a robust and highly ion‐conductive solid electrolyte interphase (SEI) layer is designed on a Li metal anode and a Ni‐rich layered cathode by incorporating chloroethylene carbonate (ClEC) as an additive in fluoroethylene carbonate‐based electrolytes. ClEC induces the formation of LiCl, which facilitates Li‐ion diffusion in the robust LiF‐rich SEI layer, thereby improving the cycle stability of the Li metal anode and suppressing microcracking of the Ni‐rich layered cathode, especially during charging and discharging at high current densities. By using the newly developed combination of electrolyte solution, an LMB featuring the Li[Ni 0.78 Co 0.1 Mn 0.12 ]O 2 cathode (2.3 mAh cm −2 , 0.1 C) affords a superior capacity retention of 80.2% over 400 cycles at high charge and discharge current densities of 2.0 C (3.6 mA cm −2 ) and 5.0 C (9.0 mA cm −2 ). This study provides insights into the use of ClEC as an electrolyte additive and highlights the importance of constructing robust and highly ion‐conductive interfaces on both Li metal anodes and Ni‐rich cathodes for high‐performance LMBs.