Rationally designed hierarchical NiCo2O4–C@Ni(OH)2 core-shell nanofibers for high performance supercapacitors

Supercapacitor is considered as a favored candidate with promising future for next-generation energy storage applications. In quest of higher electrochemical performance, the integration of carbon-based and metallic-oxide-based materials becomes necessary. Herein, a creative yet effective design of one-dimensional hierarchical nanofibers, composed of a highly conductive core (NiCo2O4 embedded carbon fiber) and a sheath of Ni(OH)2, is devised. The material is systematically fabricated by electrospinning and chemical bath deposition. Optimum electrode material exhibits high energy storage performance (1925 F g−1 at 1 A g−1) and good cycling performance (retained 87% after 5000 cycles) compared to its counterpart without Ni(OH)2 nanosheets (79% after 5000 cycles). Furthermore, the asymmetric supercapacitor assembled by this material and activated carbon delivers excellent specific capacitance performance (135 F g−1 within 1.6 V). Meantime, this asymmetric supercapacitor possesses high power density and energy density, up to 323 W kg−1 and 48 Wh kg−1, respectively, as well as outstanding rate capability, transcending most reported metal oxide carbon-based composite materials.