Ni3S4/SnS/Graphene Oxide/Carbon Nanotube Composites as Anodes for Na-Ion Batteries

Abstract

To boost the electrochemical kinetics of sodium-ion batteries (SIBs), scheming of nanocomposite materials and apprehending the synergistic effect between synthesized constituents are rationally vital. Due to high performance and superior theoretical capacity, transition-metal sulfides appear prominent anode applicants for SIBs. Still, constraints exist in their practical usage due to structural damage, leading to poor cycling stability, severe capacity loss, and low rate performance. In this study, an integrated amalgam of Ni3S4/SnS (NTS) heteroarchitecture has been fabricated with reduced graphene oxide (NTS-rGO) and carbon nanotubes (NTS-CNTs) via a scalable and green hydrothermal route. In the successive hydrothermal treatment, the sulfur ions released from sodium sulfide react with nickel and tin ions to produce NTS heterostructure and provide a synergistic effect. The morphology displays nucleation of multiple nanoseeds, which grows into nanosheets of NTS for which rGO behaves as a template growth and CNT mesh befits the bridge to link the heterostructure of NTS. For NTS-rGO and NTS-CNTs NCs, the initial charge capacity was measured as 402 and 447 mA h g–1 at a rate of 0.05 C, respectively. Furthermore, CNTs act as a passivation layer and can accommodate structural integrity and prevent nanoparticles from aggregation during prolonged cycling; hence, NTS-CNTs displays ultra-cycling stability with a Coulombic efficiency of 100%, illuminating the synergistic effect among NTS and CNT unique patterns. The charge-transfer resistance is noticed to be the lowest for hybrid heterostructural NTS-CNTs (403.2 Ω) as compared to NTS-rGO and pure NTS (526.7 and 605.9 Ω), which effectively increase the charge transportation. The transition between diffusion and capacitive currents validates that charge storage is mainly pseudocapacitive at elevated scan rates in NTS-CNTs anode which is driven by finding of swift Na ion diffusion and rapid near-surface Na storage compared to pure NTS and NTS-rGO.