Sodium-Ion Battery Full-Cell Study with a Pseudocapacitive MoSe₂-Porous N-Doped Carbon Composite Anode and Intercalated Sodium Vanadium Fluorophosphate Cathode

Despite higher conductivity and larger d-spacing (0.65 nm) of MoSe₂ compare to its analogous MoS₂ and higher theoretical capacity (∼422 mA h g⁻¹) compare to commercially available graphite, it experiences high volume expansion, sheets agglomeration during cycling, which limits their capacities and high rate application. Herein, we have shown interest in MoSe₂ materials as analogous to MoS₂ anode and grown MoSe₂ nanosheets on the nitrogen-doped carbon followed by covered with reduced graphene oxides sheets (NC@MoSe₂@rGO) composite through a simple solvothermal synthesis followed by annealing treatment. The porous NC compound could bring several advantages like, it can reserve a sufficient amount of electrolyte for easy access of Na-ion diffusion. Increasing the conductivity by introducing the doping of nitrogen on the NC structure and simultaneously rGO can reduce the volume expansion of MoSe₂ during the cyclic performance. Ex-situ XANES and XPS technique explored the sodiation mechanism of the NC@MoSe₂@rGO composite. It has been found the irreversible conversion of MoSe₂ after 1^st cycle by converting the discharged products of Mo and Na₂Se. The NC@MoSe₂@rGO anode is connected with electrolyte and a high potential Na₃V₂O₂(PO₄)₂F (NVOPF) to acquire potential applications′ approval cathode material. The full-cell delivers a voltage of operation at 2.1 V with high specific capacity of ∼176 mA h g⁻¹ (current rate of 0.05 A g⁻¹) with an energy density of ∼369.6 W h/kg _anode at 20 °C.