High performance asymmetric supercapacitor based on hydrothermally synthesized ZnO nanosheets embedded on Ni foam

Nanosheets of ZnO are fabricated on Ni foam (NF) via a single-step hydrothermal reaction and employed as an electrode material for asymmetric supercapacitors. ZnO with nanosheet structure offers remarkable structural features that provide less internal resistance and facilitate easy transportation of ions/electrons, making it eligible for promising electrode material. ZnO nanosheets reveal excellent electrochemical performance as electrode material. Specific capacitance reaches a maximum value of 1209 F g −1 at 1 A g −1 with 83% capacitance retention in an electrolyte of 3 M KOH after 5000 galvanostatic charge/discharge (GCD) cycles. The asymmetric supercapacitor ASC (ZnO@NF//AC@NF) is fabricated using ZnO nanosheets and activated carbon (AC) as positive and negative electrodes, respectively. For ASC, the specific capacitance reaches a maximum value of 87 F g −1 at 1 A g −1 with 75.5% capacitance retention after 4000 GCD cycles. The ASC exhibits an energy density of 28 Wh kg −1 and a power density of 839 W kg −1 . The outstanding electrochemical characteristics of ZnO nanosheets electrode direct their potential for electro-energy storage systems as an efficient electrode material.