Self-coupled nickel sulfide @ nickel vanadium sulfide nanostructure as a novel high capacity electrode material for supercapattery

Recently, self-coupled, mixed phase metal sulfide-based composites have attracted widespread attention as an electrode material for supercapacitors owing to their superior conductivity, high electrochemical activity and excellent redox capacity. Herein, an incorporated 2-dimensional (2D) polycrystalline phase of NiS₂@NiV₂S₄ (NS@NVS) nanostructure was synthesized via facile hydrothermal technique. The synthesized nanocomposite showed mixed crystalline phases of NiS₂ (cubic) and NiV₂S₄ (monoclinic) with 2D nanoflake morphology. The electrochemical behavior of NS@NVS electrode was investigated by three-electrode cell, which showed a maximum capacity of 520C g⁻¹ at 1 A g⁻¹ in 6 M KOH electrolyte. In addition, a supercapattery was designed with NS@NVS as a positive electrode and N-O enrich activated carbon as the negative electrode materials. The resultant supercapattery operated within a cell voltage of 1.6 V with good specific capacity (Csp) value of 78C g⁻¹ at 0.5 A g⁻¹ and exhibited high specific energy of 19.4 Wh kg⁻¹ at a specific power of 140 W kg⁻¹. Moreover, the hybrid device demonstrated a remarkable cycling stability of 90% for 10,000 charge-discharge cycles at a current density of 6 A g⁻¹. Utilizing the high energy storage performance, the fabricated supercapattery was employed as a power source to drive various portable electronic appliances.