Formation of NixCo1-xSe2 nanobelt solid solutions as competent electrode material for hybrid supercapattery

•A new systematic synthesis approach was developed to produce spindle like nanostructured NixCo1-xSe2 solid solutions with range of x = 0 to 1 and optimized the best condition for remarkable electrochemical perofmance,which foolproof the advantage of nanostructured solid solutions.•Tunable characteristics accentuated the specific capacity from 103 to 368 mAh/g (capacitance 822 to 2964F/g) with 63 to 82 % capacity retention at 20 A/g with minimum electrolyte concentration of 1.0 M KOH.•Deliver excellent energy density value of 56 Wh/kg and maximum power density of 16 kW/kg with 96 % capacity retention for 10,000 cycles.•These results highlights the symptomatic role of synthesis methodology and also interpret the relationship between the nanostructures-physicochemical properties-electrochemical performances.