A high energy density asymmetric supercapacitor from ultrathin manganese molybdate nanosheets

Abstract

<p>Manganese molybdate is highly significant to improve its energy density to meet the application requirement of hybrid vehicles and renewable energy systems. Here, we report a binder-free ultra thin manganese molybdate (MnMoO4 nH(2)O) nanosheets/nickel foam electrode for high energy density asymmetric supercapacitor by a facile one-step hydrothermal method. This binder-free electrode demonstrates a very high specific capacitance of 1271 F g(-1) at a scan rate of 5 mV s(-1). After 2000 charge/discharge cycles, 84.5% of the initial specific capacitance (945.6F g(-1)) is still maintained. Further SEM, TEM and XPS results suggest that this performance degradation can be ascribed to the mechanical expansion of MnMoO4 during the ion insertion/removal process or the dissolution of some MnMoO4 during the charge/discharge cycles. An aqueous asymmetric supercapacitor using the MnMoO4 nH2O as the cathode with an activated carbon anode can deliver an energy density of 31.6 Wh kg(-1) at a power density of 935 W kg(-1). The remarkable performance of binder-free MnMoO4 nH(2)O on Ni foam suggest their potential use as positive electrode material for high performance supercapacitors. (C) 2016 Elsevier Ltd. All rights reserved.</p>