Promoting Li⁺‐Solvents Desolvation by Engineering Nickel Single Atoms into Graphene Membrane toward Fast Sulfur Redox Kinetics

Abstract

Abstract Lithium‐sulfur (Li−S) batteries featuring high energy density are expected to be next‐generation energy storage devices, but are severely impeded by the suppressive Li + ‐solvents desolvation process at the electrode/electrolyte interface. Herein, a novel electrochemical in situ doping coupled with a self‐assembly strategy is proposed to fabricate the graphene membrane anchored by Ni single atoms (Ni‐SA‐G), aimed at promoting the dissociation kinetics of Li + ‐solvents complex by combining electrocatalysis and nanochannel sieving effect. Theoretical simulation and in situ Raman spectroscopy characterizations revealed that the Ni‐O 5 configuration within the Ni‐SA‐G membrane is capable of lowering the Li + ‐solvent dissociation energy barrier and promoting free Li + migration, thereby delivering the fast sulfur redox kinetics. In addition, taking advantage of the Ni‐SA‐G membrane with a special transport channel, the large‐sized solvent molecules and polysulfides were sieved and confined to a great degree. As a result, the Li−S batteries with the Ni‐SA‐G on separator as cathode front‐faces exhibit a high capacity of 1169 mAh g −1 with a good rate performance and outstanding long‐term cycling stability, where a capacity decay of only 0.024 % per cycle after 700 cycles can be achieved. Furthermore, the cell with a sulfur loading of 4.78 mg cm −2 delivers a high areal capacity of 4.0 mAh cm −2 at 0.2 C.