Synthesis of NASICON based (Na3V2-xMox(PO4)3/C) as high capacity and stable cycling cathode materials for Sodium-ion batteries.

Sodium-ion batteries are techno-economically viable as a complement to the lithium-ion battery market segment. Among its kind, NASICON-structured Na3V2(PO4)3/C offers improved Na+ insertion-extraction retention over high capacity, however, suffered from deterioration of cycle life and reduction of capacity retention. Establishment of the novel stoichiometric cathode by rejuvenating the interoperable parameters of calcination temperature and Mo6+ substitution on Na3V2(PO4)3/C physicochemical performance is presented. Series of Na3V2-xMox(PO4)3/C (0≤ x ≤1) were synthesized by the self-catalysed sol-gel route have been investigated via experimental work and Density Functional Theory (DFT) simulation, to resolve these issues. Thermal Gravimetric Analyzer (TGA) designed optimum heat treatment procedure while X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared (FTIR) results confirmed the Mo6+ partial replacement on the V3+ site lattice resulting in significant electrochemical enhancement exhibited by Charge-Discharge (CD), Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) profile. Na3V1.7Mo0.3(PO4)3/C demonstrates the highest specific capacity of 122 mAh g-1 at 0.2C current rate. Two potential discharged plateaus are observed at 3.4 V and 1.6 V (vs. Na+/Na), corresponding to the V3+/V4+ and V2+/V3+ redox couple’s activities respectively. Varied Mo6+ substitutions in Na3V2(PO4)3/C crystalline structure indicate variations in d-spacing and lattice parameter values. Interestingly, Na3V1Mo1(PO4)3/C corresponds to the highest Mo6+ concentration exhibits an extended voltage plateau in the low voltage region at 1.6 V which is promising as an anodic electrode for Na-ion batteries.