MoS2 nanosheets grown on carbon cloth as a bifunctional cathode for long-life Na–O2 batteries

Abstract

When sodium (Na)–oxygen (O2) batteries discharge, O2 is reduced on the cathode to form solid sodium oxides deposited on cathode, severely impeding the mass transfer path and causing large voltage polarization, low energy efficiency and poor rate performance. Therefore, a novel cathode is the key to solving the above issues. Here, in-situ growing molybdenum disulfide on carbon cloth (MoS2/CC) as a binder-free cathode is prepared by a simple and facile hydrothermal method. When this cathode is tested in Na–O2 batteries, it presents enhanced oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalytic activity as well as large discharge capacity. What's more, Na–O2 batteries with the MoS2/CC cathode simultaneously produce sodium superoxide (NaO2) and poor crystalline sodium peroxide (Na2O2), which greatly reduces the charge potential.