A high-performance electrode for supercapacitors: Silver nanoparticles grown on a porous perovskite-type material La0.7Sr0.3CoO3−δ substrate

Supercapacitors have potential for many emerging energy storage applications because of their excellent power density and long cycling stability. However, their applicability is often limited by the relatively low energy density. Here we report our findings in design, fabrication, and testing of a composite electrode composed of Ag nanoparticles grown directly on a porous perovskite-type material La 0.7 Sr 0.3 CoO 3−δ (LSC) substrate. When tested in KOH aqueous electrolyte, the electrode (with a high mass loading of Ag nanoparticles of 28.6   mg   cm −2 ) demonstrates an areal capacity of 14.8   F   cm −2 (specific capacitance of 517.5   F   g −1 and volumetric capacitance of 262.5   F   cm −3 ) at 1   mA   cm −2 , while maintaining outstanding cycle stability (85.6% retention after 3000 cycles at 50   mA   cm −2 ). An asymmetric supercapacitor (Ag/LSC//carbon cloth) with a wide voltage of 1.8   V displays a high energy density of 21.9   mWh   cm −3 and an excellent stability. The superior capacitive performance can be ascribed to the porous, conductive and stable LSC framework, the uniform distribution and high mass loading of Ag nanoparticles on LSC, and the effective unitization of redox process.