Perovskite SrCo_0.9Nb_0.1O_3−δas an Anion-Intercalated Electrode Material for Supercapacitors with Ultrahigh Volumetric Energy Density

We have synthesized and characterized perovskite-type SrCo_0.9Nb_0.1O_3−δ(SCN) as a novel anion-intercalated electrode material for supercapacitors in an aqueous KOH electrolyte, demonstrating a very high volumetric capacitance of about 2034.6 F cm⁻³(and gravimetric capacitance of ca. 773.6 F g⁻¹) at a current density of 0.5 A g⁻¹while maintaining excellent cycling stability with a capacity retention of 95.7 % after 3000 cycles. When coupled with an activated carbon (AC) electrode, the SCN/AC asymmetric supercapacitor delivered a specific energy density as high as 37.6 Wh kg⁻¹with robust long-term stability.