Monodispersed MnOx-CeO2 solid solution as superior electrocatalyst for Li2S precipitation and conversion

Abstract

The precipitation and conversion of Li2S are the main obstacles for practical applications of lithium-sulfur batteries, owing to the high interfacial energy barrier of the reactions and the passivation of catalysts during Li2S precipitation. A monodispersed MnOx-CeO2 solid solution nanoparticles grown on reduced graphene oxide (MnOx-CeO2@rGO) is designed as effective electrocatalyst to facilitate the precipitation and conversion of Li2S. Alien Mn atoms doping modulates the electronic structure of CeO2 matrix and induces more oxygen vacancies, which facilitates the adsorption of lithium polysulfides (LiPSs) and boots the intrinsic catalytic activity for Li2S nucleation. Moreover, the monodispersity of ultra-small MnOx-CeO2 nanoparticles can provide enough active facets for sufficient Li2S precipitation. To reveal the electrocatalytic effect of MnOx-CeO2@rGO on Li2S precipitation, mesoporous SiO2@rGO nanosheets with numerous polar surface for strong LiPSs adsorption is adopt as a reference. The results of potentiostatic discharge deposition indicates that MnOx-CeO2@rGO reduces the overpotential for the rapid Li2S precipitation, avoiding the accumulation of LiPSs on the active sites. Such features offer the cell with MnOx-CeO2@rGO coated separator an excellent high rate capacity (630 mAh g−1 at 3C) and long-term cyclic stability (capacity fading of 0.036% per cycle at 1C for 1000 cycles).