Peipei Liu,Jiang Liu,Shuang Cheng,Weizi Cai,Fangyong Yu,Yapeng Zhang,Peng Wu,Meilin Liu
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.
Perovskite oxides have attracted significant attention as capacitor electrode materials owing to their unique physical and electronic properties. In this paper, a novel La 0.7 Sr 0.3 CoO 3-δ (LSC)@MnO 2 core–shell nanorod was synthesized by controlled electrospinning combined with hydrothermal synthesis. The LSC, as a typical perovskite-type material, with excellent stability and ion–electron double conductivity, can perfectly serve as conductive backbone. Grid-like MnO 2 nanosheets are grown on LSC to form a unique core/shell nanostructure, could effectively improve the electrochemical performance of MnO 2 . The grid-like MnO 2 nanosheets shell significantly increase the effective area over which the reaction may take place and reduce the ion/electron transmission distance, which is beneficial in that it shifts in ions and electrons, enhancing the electrochemical reaction kinetics thereof. LSC@MnO 2 core/shell nanorods demonstrated good electrochemical performance with high capacitance (570 F g −1 at 1 A g −1 ), and revealed excellent cycling stability (capacitance retention remains at 97.2% after 5000 cycles). The asymmetric supercapacitor device (LSC@MnO 2 //AC) displayed a desirable energy density of 37.6 W h kg −1 at 375 W kg −1 , and still remains at 23.3 W h kg −1 at a high power density of 7489.3 W kg −1 , indicating that the LSC@MnO 2 nanorods are an outstanding pseudo-capacitive electrode material, with significant potential for application in high-performance supercapacitors.
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