Synergistic Effects of FeCo Bimetallic Single-Atom Catalysts: Accelerating the Redox Conversion of Polysulfides and Inhibiting the Growth of Lithium Dendrites in Lithium–Sulfur Batteries

Abstract

The shuttle effect of lithium polysulfides on a positive electrode and the uncontrollable growth of lithium dendrites on a negative electrode are the two fundamental crucial problems of lithium–sulfur batteries (LSBs). These problems have led to low actual specific capacity and poor rate performance of these batteries. In order to resolve these issues at both electrodes simultaneously, we used Fe and Co bimetallic atoms to dope the three-dimensional dodecahedron material ZIF-8, which is used as a monomer to construct a functional modified separator. Owing to the porous structure, high specific surface area, notable interfacial electron conductivity after carbonization, and the synergistic catalytic effect of Fe and Co bimetallic doping, the FeCoDA-CN@PP separator suppresses the shuttle effect of lithium polysulfides (LiPSs) on the positive electrode and ensures the higher ion/electron rapid diffusion and hence efficient lithium growth during the cycling on the negative electrode. The demonstrated LSBs with the FeCoDA-CN@PP separator deliver a specific discharge capacity of 1404 mAh g–1 at 0.1C. After 500 provided cycles at a rate of 1C, it still offers a specific discharge capacity of 541 mAh g–1 and a stable Coulombic efficiency of >98% with a capacity decay rate of 0.08% per cycle. At a discharge rate of 1 mA cm–2, the symmetrical battery with the FeCoDA-CN@PP separator was still able to maintain a stable voltage distribution and an overpotential of 31 mV after 500 h. The outcomes pave an auspicious approach for the development of LSBs with long-cycle life and higher capacity, which may further promote the industrialization and commercialization of LSBs.