Facile synthesis of FeS2/MoS2 composite intertwined on rGO nanosheets as a high-performance anode material for sodium-ion battery

In this work, we demonstrate the FeS2/MoS2 composite embedded in rGO nanosheets (FeS2/MoS2-rGO composite) as an anode material for sodium-ion battery. The FeS2/MoS2 composite material was synthesized by one step hydrothermal method, and the prepared particles were wrapped by reduced graphene oxide (rGO) nanosheets, which facilitated the electronic transport between the particles, and suppressed the volume expansion of active materials as well as the polysulfide dissolution into the electrolyte during cycling. The FeS2/MoS2-rGO composite electrode delivered a high initial discharge capacity of 468.0 mA h g???1 and exhibited good cycling stability at a current density of 100 mA g???1. Due to the pseudocapacitive behavior of FeS2/MoS2-rGO electrode, a high reversible capacity of 346.5 mA h g???1 was achieved at 3000 mA g???1, which was much higher than those of FeS2, MoS2 and FeS2/MoS2 composite electrodes. The sodium-ion full cell assembled with FeS2/MoS2-rGO composite anode and Na3V2(PO4)2F3 cathode exhibited a high reversible capacity with good cycling stability, which demonstrates that the prepared FeS2/MoS2-rGO composite can be used as a promising anode material for sodium-ion batteries. ?? 2019 Elsevier B.V

Electrochemical Behavior of Li+, Na+ and K+ Ion Electrolyte in Na0.33V2O5 Symmetric Pseudocapacitor with High-Performance and Extremely High Cyclic Stability

A high performance symmetric supercapacitor was fabricated using Na0.33V2O5 nanocomposite synthesized via a simple co-precipitation technique. The structural and morphological investigation showed that the synthesized Na0.33V2O5 nanocomposite exhibited a monoclinic structure with nanorod like morphology. The electrochemical properties of the Na0.33V2O5 symmetric supercapacitor was studied utilizing three different aqueous electrolytes such as 1M of LiCl, NaCl and KCl respectively. Interestingly, the fabricated Na0.33V2O5 symmetric supercapacitors exhibited excellent electrochemical capacitance behavior in all the electrolytes with a maximum specific capacitance value of 168 F g-1 in 1M LiCl, 146 F g-1 in 1M NaCl and 132 F g-1 in 1M KCl electrolytes at 0.5 A g-1 discharge current density. In addition, Na0.33V2O5 symmetric supercapacitors demonstrated an excellent cyclic stability especially in 1M NaCl electrolyte with high capacitance retention of ~81% after 50,000 charge/discharge cycles

Enhanced sodium-ion storage capability of P2/O3 biphase by Li-ion substitution into P2-type Na0.5Fe0.5Mn0.5O2 layered cathode

Integration of P2 and O3 phases in Na0.5Fe0.5Mn0.5O2 cathode via Li-ion substitution is proposed to enhance its electrochemical performance for sodium-ion battery applications. The formation of P2 and the combination of P2/O3 intergrowth were confirmed by X-ray diffraction refinement, high resolution transmission electron microscopy and X-ray photoelectron microscopy analyses. Various content of lithium was used to find optimum P2+O3 combinations. The optimized Li-ion substituted Na-0.5(Li0.10-Fe0.45Mn0.45)O-2 showed a high initial discharge capacity of 146.2 mAh g(-1) with improved cycling stability, whereas the pristine Na0.5Fe0.5 Mn0.5O2 initially delivered a discharge capacity of 127.0 mAh g(-1). In addition, the combination of P2+O3 increased its average voltage, which is important for achieving high energy density sodium-ion batteries. Overall, the prepared Na-0.5 (Li0.10Fe0.45Mn0.45)O(2)electrode exhibited the improved cycling performance in terms of reversible capacity and rate capability compared to pristine Na0.5Fe0.5Mn0.5O2 electrode material. (C) 2018 Elsevier Ltd. All rights reserved