Elucidating an efficient super-capacitive response of a Sr2Ni2O5/rGO composite as an electrode material in supercapacitors

Abstract

Mixed transition metal oxides have emerged as efficient electrode materials because of their significant cycling stability, and superior capacitance values, resulting in remarkable electrochemical outputs. In this regard, Sr₂Ni₂O₅/rGO composites were synthesized using a facile solvothermal method to achieve efficient electrochemical pursuits. X-ray diffraction confirmed the formation of finely crystallized samples with the phase evolution from orthorhombic to hexagonal. Morphological studies using field emission scanning electron microscopy depicted the desired porosity in samples with well-defined shapes and sizes of homogeneously distributed grains. Elemental analysis verified the pictorial depiction of sample compositions in terms of their stoichiometric ratios. The composite sample with composition Sr₂Ni₂O₅@15%rGO exhibited superior electrochemical performance compared to other samples, depicting the highest specific capacitance of 148.09 F g⁻¹ at a lower scan rate of 0.005 V s⁻¹ observed via cyclic voltammetry. In addition, the cyclability performance of Sr₂Ni₂O₅@15%rGO exhibits 68.5% capacitive retention after 10 000 cycles. The energy density as determined using a two-electrode system remained 4.375 W h kg⁻¹ for the first cycle which reduced to 1.875 W h kg⁻¹ for the 10 000^th cycle, with a maximum power density of 1.25 W kg⁻¹. The Nyquist plot represented less barrier to charge transfer. The electrode with particular composition Sr₂Ni₂O₅@15%rGO emerged as significant, exhibiting a superior surface capacitive charge storage, that makes it a potential candidate as an electrode material.