Stable and Efficient Lithium Metal Anode Cycling through Understanding the Effects of Electrolyte Composition and Electrode Preconditioning

Stable metal anode cycling for high energy density batteries can be realized through modification of electrolyte composition and optimization formation protocols, i.e., electrode interphase preconditioning conditions. However, the relationship between these electrochemical performance is still unclear due to a lack molecular level understanding electric double layer (EDL) changes with two parameters. Herein, we examine impact ionic liquid (IL) (salt concentration cosolvent) conditions on Li EDL affecting both solid–electrolyte (SEI) deposition morphology. Each results in particular interfacial Li-ion solvation environment, which controls reductive stability, potential, ultimately properties SEI. The latter dependent such as IL cation/Li-anion ratio or presence other surface active additives. It found that superconcentrated electrolyte, current (≥10.0 mA cm–2/1.0 mAh cm–2) beneficial during step, compared case low salt-containing IL. This correlates predominance Lix(anion)y (x > y) at highly negatively charged interface, present when higher densities are used preconditioning, suggested by dynamics simulations. In contrast, lower viscosity containing 20 wt % ether cosolvent, more moderate step (6.0 leads an optimized morphology improved performance. consequence competing processes ion transport Li+ flux intrinsic reduction kinetics occurring negative electrode.