Structural engineering design of CoTe@NixSy core-shell nanowires supported by cobalt foams and functional application in aqueous/flexible hybrid supercapacitors

Abstract

CoTe@NixSy core-shell nanowires are designed and grown on cobalt foams via hydrothermal and electrodeposition method. Structural characterizations indicate the tightly coating of NixSy nanosheets around CoTe nanowires forms the novel core-shell nanowires. Benefiting from this structural engineering design, CoTe@NixSy core-shell nanowires supported by cobalt foams deliver the high areal specific capacitance of 7.56 F cm−2 at 3 mA cm−2 and retention rate of 81.3% after experiencing 5000 cycles. It needs to be specially mentioned that CoTe@NixSy core-shell nanowires were functionally applied in aqueous/flexible hybrid supercapacitors with activated carbon as the negative materials. The aqueous hybrid devices exhibit a maximum areal energy density of 0.77 mWh cm−2 at 2.52 mW cm−2 and retention rate of 81.9% after 5000 cycles. Meanwhile, the flexible hybrid devices show superior energy-storage performance, such as high volume energy density of 3.95 mWh cm−3 at 22.64 mW cm−3, improved cycle stability (82.1% after experiencing5000 cycles), and remarkable flexibility. This work not only demonstrates CoTe@NixSy core-shell nanowires as the promising candidate of energy-storage device; but also provides a novel strategy for high-performance electroactive materials.