Co decoration of molybdenum sulfide and carbon for improving lithium ion capacity of large monolayer MXene cathodes

Abstract

Although two-dimensional Ti3C2Tx MXene has rich surface chemistry, hydrophilic surface, superconductivity and cationic insertion ability, it still has a long way to go to fully prosecute its sue as a cathode material for lithium-ion batteries due to its small size and low theoretical capacity. Large Ti3C2Tx monolayer nanosheets (M-Ti3C2Tx) are prepared by etching carefully selected Ti3C2Tx MXene phase particles in LIF and HCl mixture. MoS2 nanosheets are self-assembled uniformly in-situ on the surface of the large M-Ti3C2Tx MXene nanosheets. Amorphous carbon layer is coated on the surface of the products by glucose annealing treatment. Appropriate amount of CTAB is added during the reaction to inhibit the spheroidization of MoS2. The uniform vertical growth of MoS2 nanosheets ensures the large specific area and high capacity of the final products. The amorphous carbon layer suppresses the volume expansion of MoS2 nanosheets and improves the bonding between MoS2 nanosheets and monolayer Ti3C2Tx MXene nanosheets. The sandwich-like M-Ti3C2Tx@MoS2@C nanohybrid electrodes deliver high reversible capacity and excellent cycling performance. Their rate capacity remains at 724.9 mA h g−1 even at current density of 2000 mA g−1. After 1000 cycles at current density of 500 mA g−1, the nanohybrid electrodes still maintain reversible capacity at 764 mAh g−1. This work opens a window for the development of smart electronic devices with high battery life and rapid charging requirements.