A Tubular Sandwich-Structured CNT@Ni@Ni2(CO3)(OH)2 with High Stability and Superior Capacity as Hybrid Supercapacitor

Development of highly stabile battery-type electrode materials with superior capacity has been a critical challenge or hybrid supercapacitors. We report a high-performance electrode material tubular sandwich-structured CNT@Ni@Ni-2(CO3)(OH)(2) synthesized via a Scalable dynamic controlled in Situ reduction-chemical deposition process. Applied as a battery-type electrode material this novel exhibits excellent electrochemical stability majorly attributed to the Ni midshell serving a dual role as capacity supplement and electron highway which to out knowledge was incorporated into the nanocomposite electrodes for the first time. Also benefiting from the high conductivity of carbon. nanotubes (CNTs) and the high capacity of the atmorphous NiOOH ultrathin film [converted from the Ni-2(CO3)(OH)(2) outer shell] the resulting CNT@Ni@Ni-2(CO3)(OH)(2) material as a battery-type electrode achieves a superior capacity of 221 mAh.g(-1) at 5 A.g(-1) with 76% capacity retention at 50 A.g(-1) and maintains 81% capacity after 9000 cycles at 5 A.g(-1). An advanced aqueous hybrid supercapacitor using activated carbon and CNT@Ni@Ni-2(CO3)(OH)(2) nanocomposite as the negative and positive electrodes respectively delivers a high energy density of 179 Wh.kg(-1) at a power density of 2880 W.kg(-1) with capacitance retention in excess of 85% over 5500 cycles. The outstanding performance demonstrates its practical potential in advanced hybrid supercapacitors.