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

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 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-O5 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 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.