Mesoporous hollow ZnCo 2 S 4 core-shell nanospheres for high performance supercapacitors

Abstract In this work, ZnCo 2 S 4 nanospheres in a hollow core-shell structure are synthesized by a facile self-template route. The synthesis route involves a solvothermal method synthesis of Zn-Co precursor solid spheres in glycerol and isopropanol and then sulfidation to obtain hollow ZnCo 2 S 4 core-shell nanospheres. The synthesized obtain hollow ZnCo 2 S 4 core-shell nanospheres possess mesoporous texture and its specific surface area is as large as 117.3 m 2 g −1 . Benefiting from the remarkable advantages such as novel hollow core-shell structures, mesoporous and large specific surface area, these ZnCo 2 S 4 as electrode material exhibit a specific capacitance of 1045.3 F g −1 at 2.0 A g −1 and superior long-term cycling performance (around 4.5% loss after 5000 continuous cycling). Moreover, an asymmetric supercapacitor assembled with hollow ZnCo 2 S 4 core-shell nanospheres and activated carbon delivers the energy density of 51.7 Wh kg −1 at a power density of 1700 W kg −1 . Even at 6800 W kg −1 , the energy density can still reach 42.5 Wh kg −1 . This work not only demonstrates hollow ZnCo 2 S 4 core-shell nanospheres utilized as a promising candidate for supercapacitors, but also provides a simple and cost-effective strategy for designing and synthesizing other high performance hollow structured metal-sulfides for electrochemical energy storage.