Novel MoSi2 catalysts featuring surface activation as highly efficient cathode materials for long-life Li–O2 batteries

Abstract

Searching for highly efficient and low cost electrocatalysts is an urgent challenge to provide high capacity and long cycle life Li–O₂ batteries (LOBs). In this work, the highly efficient electrocatalytic properties of MoSi₂ were first demonstrated using particles prepared by a solid–state reaction method. The surface was activated, playing a dominant role in the electrocatalytic performance. After acid etching to remove SiO₂ impurities arising from the surface oxidation, MoSi₂ exhibited excellent bifunctional electrocatalytic properties for LOBs. Mo⁶⁺ on the surface contributed to the initial low overpotentials of 0.45 V (3.2 V for the OER and 2.75 V for the ORR) and transformed into Mo⁴⁺ for a long cycle life. As a consequence, outstanding rate capabilities of 12 708 mA h g⁻¹ at 100 mA g⁻¹ and 10 794 mA h g⁻¹ at 800 mA g⁻¹, and excellent cycle durability of 215 and 90 cycles at a limited capacity of 1000 mA h g⁻¹ at 200 and 500 mA g⁻¹, respectively, were obtained for the MoSi₂ cathode.