Electrochemical Properties and Reaction Mechanism of NiTi2S4 Ternary Metal Sulfide as an Anode for Lithium Ion Battery

Herein, NiTi2S4 (NTS) ternary sulfide was investigated as a novel and promising lithium ion battery (LIB) anode for its high theoretical capacity and electrical conductivity. NTS was synthesized by a facile high energy mechanical milling method and its electrochemical properties have been examined. Compared to bare TiS2 and physically mixed Ni-2TiS2 composite, NTS exhibited the better cyclability delivering the reversible capacity of 635 mAh g–1 after 50 cycles at a current density of 1000 mA g–1. The excellent cycle performance was attributed to its unique reaction mechanism where Ni nanocrystallites were generated after the first conversion reaction during lithiation and remained inactive during the subsequent cycles. In situ generated Ni nanocrystallites were finely distributed inside the active matrix, restrained the volume change of the active material, and increased the electrical conductivity, leading to enhanced electrochemical properties. Moreover, the addition of 20 wt % graphene improved the cycle performance and rate capability of NTS. The NTS-G composite retained the reversible capacity of 452 mAh g–1 after 1000 cycles at the current density of 5000 mA g–1.