Hierarchical CoS@MoS2 core-shell nanowire arrays as free-standing electrodes for high-performance asymmetric supercapacitors

Abstract The free-standing hierarchical core-shell nanoarchitectures exemplify the substantial interest in fabricating next-generation electrode materials for energy storage systems such as in supercapacitors (SCs). Herein, the hierarchical 3D CoS@MoS2 nanowire arrays (NWAs) are synthesized through a cost-effective hydrothermal method and followed by an effective sulfurization. The structural and morphological investigations of hierarchical 3D CoS@MoS2 NWAs are carried out for each stage. The optimal 3D CoS@MoS2 NWAs yields a high specific capacity of 374.75 mA h g−1 and an areal capacity of 1.39 mA h cm−2 at a current density of 4 mA cm−2, exceptional rate performance (∼70.1% retention of the capacity at 20 mA cm−2), and remarkable cycling performance (∼96.2% retention of the capacity after 10000 consecutive charge-discharge cycles), which are superior to the corresponding CoS nanowires and MoS2 nanosheets counterparts. The assembled CoS@MoS2//Fe2O3@rGO ASC exhibit a broader working potential window of 1.7 V, a superb electrochemical energy storage property (energy density of 95.7 W h Kg−1 at the power density of 711.2 W kg−1), and excellent cycling stability (∼95.5% retention of capacity after 10,000 cycles), demonstrating their promising application in ultrahigh energy density and ultra-long cycling stability SCs.