Tuning kinetics of SnS/Ni3S4 binary sulfides for high rate and long cyclic lithium-ion batteries

Abstract

Nanomaterials synergy in a binary system offers a great opportunity for the development of high-performance electrode material for Lithium-ion batteries (LiBs). So far SnS/Ni₃S₄ binary sulfides are scarcely investigated as an anode for LIBs. In this work, to intrinsically enhance the kinetics of SnS, SnS/Ni₃S₄ (SN-x) binary sulfides were synthesized by introducing nickel sulfide with different stoichiometric ratios (0.5, 1, 2, and 3). The developed electrode (SN-2) delivers an initial discharge capacity of 2567 mA h g⁻¹ and a high reversible capacity of 360 mA h g⁻¹ at a current rate of 300 mA g⁻¹ after 180 cycles with a Coulombic efficiency of over 97%. The electrochemical impedance spectroscopy (EIS) and density functional theory (DFT) confirm the improved kinetics of the SN-2 electrode as compared to other electrodes. The significantly enhanced performance of the SN-2 electrode can be attributed to the addition of an optimized amount of Ni₃S₄, synergistic effects between SnS and Ni₃S₄, generation of more active sites and structural integrity. This work suggests that the prepared SnS/Ni₃S₄ binary sulfides exhibit great promise for the development of efficient energy storage devices.