Ionic Liquid Electrolyte with Weak Solvating Molecule Regulation for Stable Li Deposition in High‐Performance Li−O2 Batteries

Abstract

AbstractLi−O2 batteries with bis(trifluoromethanesulfonyl)imide‐based ionic liquid (TFSI‐IL) electrolyte are promising because TFSI‐IL can stabilize O2− to lower charge overpotential. However, slow Li+ transport in TFSI‐IL electrolyte causes inferior Li deposition. Here we optimize weak solvating molecule (anisole) to generate anisole‐doped ionic aggregate in TFSI‐IL electrolyte. Such unique solvation environment can realize not only high Li+ transport parameters but also anion‐derived solid electrolyte interface (SEI). Thus, fast Li+ transport is achieved in electrolyte bulk and SEI simultaneously, leading to robust Li deposition with high rate capability (3 mA cm−2) and long cycle life (2000 h at 0.2 mA cm−2). Moreover, Li−O2 batteries show good cycling stability (a small overpotential increase of 0.16 V after 120 cycles) and high rate capability (1 A g−1). This work provides an effective electrolyte design principle to realize stable Li deposition and high‐performance Li−O2 batteries.