Fe3O4/graphene-oxide/chitosan hybrid aerogel based high performance supercapacitor: effect of aqueous electrolytes on storage capacity & cell stability

In this work, Fe3O4/graphene-oxide/chitosan aerogel (GCFA) with 3-D interconnected structure (average pore size ∼8.4 nm) and moderate BET surface area (∼59 m2/g) is synthesized by hydrothermal route. Three different hybrid symmetric supercapacitor cells are fabricated using GCFA as active electrode material, using basic (6M KOH: cell-1), acidic (1M H2SO4: cell-2), & neutral (Na2SO4: cell-3) as electrolyte mediums. Subsequently, a comprehensive study is carried out to assess the effect of electrolyte on the porous architecture, charge storage capacity, rate capability and cyclic stability. Besides, cell-3 also shows good cyclic stability with low initial fading (∼15%), good capacity retention (∼84%) It has been observed that cell-3 displayed better performance (specific capacitance ∼160 F g−1, specific energy∼14.6 Wh kg−1 and specific power∼0.77 kW kg−1) than either of cell-2 (∼160 F g−1, ∼7.84 Wh kg−1 and ∼0.45 kW kg−1) or cell-1 (∼102 F g−1, ∼1.54 Wh kg−1 and ∼0.14 kW kg−1) and excellent coulombic efficiency (∼91%) even after 10,000 charge-discharge cycles. This is attributed to the better pore accessibility, stability of residual surface functionalities under potential cycling, and least screening for intra-pore shuttling of counter-ions under neutral medium.