MoSe₂@CNT Core–Shell Nanostructures as Grain Promoters Featuring a Direct Li₂O₂ Formation/Decomposition Catalytic Capability in Lithium‐Oxygen Batteries

Abstract

Abstract For lithium‐oxygen batteries (LOBs), the strong oxidant intermediate and byproducts during the charge/discharge process are the main reasons for the degradation of the electrochemical performance. Searching for highly efficient catalysts for the direct formation/decomposition of Li 2 O 2 is essential for the development of LOBs. In this study, core–shell nanostructured MoSe 2 @CNT with uniform MoSe 2 coating layers are purposefully synthesized through a facile hydrothermal strategy to address the negative intermediate and side‐product issues, therefore enhancing the battery performance. The continuous and multiwalled MoSe 2 layers can not only work as grain promoters that induce the initial nucleation and growth of equiaxed Li 2 O 2 grains on the cathode surface even under a high rate, but also prevent the byproducts formation from corrosive issues between carbon and electrolyte. Moreover, density functional theory (DFT) calculations reveal the intrinsic layer dependent direct formation/decomposition catalytic capability of 2D MoSe 2 and the LiO 2 avoidable reaction pathway during the discharge/charge process, theoretically revealing the direct epitaxial growth mechanisms of Li 2 O 2 . As a consequence, the MoSe 2 @CNT cathode exhibited a superior specific capacity over 32 000 mAh g −1 , excellent rate capabilities, and ultralong cycle life of 280 cycles at a high rate of 500 mA g −1 .