Improvement of Redox Kinetics of Dendrite-Free Lithium-Sulfur Battery by Bidirectional Catalysis of Cationic Dual-Active Sites

Three-dimensional cation dual-active-sitecatalytic strategyof 3DCS-FMO@C to promote the development of high-energy-density lithium-sulfurbatteries for sustainable energy storage. The practical application of lithium-sulfurbatteries(LSBs)is hampered by the slow lithium polysulfide (LIPS) conversion kineticsand the uncontrollable anode-metal lithium dendrites. Herein, a three-dimensionalcation dual-active-site eggshell structure compound (3DCS-FMO@C) wassynthesized by soft template, ion exchange, and pyrolysis to modifythe commercial separator. Experimental and theoretical analysis resultsshowed that Mn2+ and Fe2+ sites in 3DCS-FMO@Ccan synergistically adsorb LIPSs, effectively regulate the bidirectionalconversion dynamics of intermediate liquid-phase LIPSs and solid-phaselithium sulfide, and reduce the energy barrier of the reaction. The3DCS-FMO@C-modified separator with high mechanical stability and noreduction in ion diffusion also had a lithiophilic central core thatcan homogenize the lithium-ion flow, thereby inhibiting the dendritegrowth of lithium. Based on the above advantages, 3DCS-FMO@C-modifiedseparator LSBs had better electrochemical performance, including aninitial capacity of 1530 mAh g(-1) at 0.1C and anultralow decay rate of 0.029% for 1000 cycles at 0.5C. A high areacapacity of 8.7 mAh cm(-2) was achieved even withhigh sulfur loading and poor electrolyte. This work provided a basisfor understanding the bidirectional catalysis for practical applicationin LSBs and simultaneously solved the problem of lithium dendrites.