Binder and conductive agent-free electrode for the excellent aqueous asymmetrical supercapacitor

摘要

Aimed at improving the electric efficacy of supercapacitor, we designed a novel binder and conductive agent-free electrode material by integrating varying amounts of aluminum into ultrathin nanosheets of NiCo layer double hydroxide on nickel foam via a one step hydrothermal treatment. We investigated the remarkable impact of Al on the morphology and electrical performance of NiCo_2Al_x-OH. A transfiguration occurred from β-phase of NiCo_2- OH to α-phase of NiCo_2Al_x-OH with the introduction of Al in NiCo-OH. The NiCo_2Al_(0.5)-OH electrode has 1570 F g~(-1) specific capacitance at a current density of 2 A g~(-1). A high performance aqueous asymmetric supercapacitor (NiCo_2Al_(0.5)-OH//AC) was designed with NiCo_2Al_(0.5)-OH as the positive electrode. This device demonstrated an excellent energy density of 56.8 W h kg~(-1) at 618 W kg~(-1) power density and 98% capacitance retention over 6000 cycles at a current density of 20 A g~(-1).