Synthesis of MoS2/Co9S8@CoNC by impregnation and calcination for highly efficient lithium-O2 batteries

Abstract

The activity of electro-catalyst on oxygen cathode is a key factor affecting the property of lithium-O2 batteries (LOBs). In this work, zeolitic imidazolate framework (ZIF–67) was impregnated in (NH4)2MoS4 solution, and then through centrifugation and calcination, nano-MoS2 and Co9S8 were grown on the surface of CoNC skeleton. The composite has mesoporous structure and abundant active groups such as Co, Co9S8, Co-N bond, Mo-N bond and active edges of MoS2 with sulfur vacancies. The coating of ultra-thin MoS2 nanosheets can improve the stability of CoNC skeleton. The Mo component induces the transformation of amorphous carbon of CoNC to graphitic carbon during calcination in order to improve conductivity of the composite. This study shows that MoS2/Co9S8@CoNC is good electro-catalyst for O2 reduction and evolution reactions (ORR/OER). The LOBs with MoS2/Co9S8@CoNC oxygen cathode show high specific discharge capacity (18162 mA h g−1) and good cycle performance (304 cycles).