The development of innovative materials with excellent electrochemical properties is immediately needed to dispel the problems of battery performance. In the present study, the hydrothermal method was applied to synthesize bimetallic sulfides (ZnS:SnS), which were then anchored on reduced graphene oxide (rGO) to produce ZnS:SnS@rGO composites or combined with carbon nanotubes (CNTs) to achieve ZnS:SnS@CNT composites. These composites were then investigated as electrodes for sodium-ion batteries, and their charge storage properties were analyzed. Nanostructures and the morphology of the as-prepared composites were examined by X-ray diffraction, scanning or transmission electron microscopy, and X-ray photoelectron spectroscopy. The specific charge capacity for the ZnS:SnS@CNT composite reaches 364 mA h g–1, while the ZnS:SnS@rGO composite shows 343 mA h g–1 at 0.1 C. Moreover, the inclusion of the conductive matrices also stabilizes the cycle life and rate capability even up to 5.0 C. Nyquist plots obtained as a result of impedance spectroscopy illustrate that the ZnS:SnS@CNT composite electrodes enable fast charge transfer due to lower charge transfer resistance of 44.4 Ω as compared to ZnS:SnS@rGO (i.e., 51.5 Ω) and bare ZnS:SnS (i.e., 68 Ω) electrodes. Electrochemical analysis proves that the presence of dual metal-sulfide ions combined with reduced graphene or CNTs as a conductive matrix results in considerably improved ion storage properties owing to the enhanced electronic conductivity, cushioned volume expansion, and provision of ionic transport highways through the electrode.

No 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.

No abstract

No abstract