Superior asymmetric supercapacitor based on Ni-Co oxide nanosheets and carbon nanorods

Nickel and cobalt (Ni-Co) binary oxide nanosheets with mesoporous structure are prepared by a facile approach based on the formation and disassociation of nickel/cobalt-citrate complex, and they show an ultra-high Faradaic capacitance up to 1846 F g(−1) and excellent rate capability. On this basic, advanced aqueous asymmetric supercapacitors (AASs) are successfully built by using the Ni-Co oxide as the positive electrode and three kinds of activated carbons respectively as the negative electrode. As-made AASs are able to work reversibly in a full operated voltage region of 0–1.6 V and exhibit outstanding electrochemical performance. Among them, activated polyaniline-derived carbon (APDC)//Ni-Co oxide AASs shows the highest specific capacitance of 202 F g(−1), the maximum energy density of 71.7 Wh kg(−1), and superior combination of high energy and power density (a energy density of 41.6 Wh kg(−1) at a high power density of 16 kW kg(−1)).