A simple l-cysteine-assisted method for the growth of MoS2nanosheets on carbon nanotubes for high-performance lithium ion batteries

Abstract

We introduce a simple process to synthesize few-layered MoS₂ nanosheets supported on coaxial carbon nanotubes through an L-cysteine-assisted hydrothermal route, in which L-cysteine, a cheap and ordinary amino acid, plays a fundamental role in controlling the morphology of the hybrid material and the binder to help the growth of MoS₂ nanosheets on the surface of the carbon nanotubes. It is also demonstrated that the polypeptide formed by L-cysteine can be transformed into amorphous carbon by heat treatment under an inert atmosphere. The materials exhibit high capacity and excellent cycling performance when used as anode materials for lithium ion batteries. The specific capacity of a composite with 1 : 4 molar ratio of MoS₂ to carbon nanotubes is 736.5 mAh g⁻¹ after the first cycle, increased for several initial cycles, and remains at 823.4 mAh g⁻¹ even after 30 cycles, when cycled at a current density of 100 mA g⁻¹. At a very high current density of 1600 mA g⁻¹, the material shows a stable capacity of approximately 530 mAh g⁻¹ after 30 cycles. The noteworthy improvement in the electrochemical performance of the material can be attributed to their unique structure and the synergistic effects of amorphous carbon and few-layered MoS₂.