Hierarchical WO3@MnWO4 core-shell structure for asymmetric supercapacitor with ultrahigh cycling performance at low temperature.

In this work, for the first time we report a kind of novel WO3@MnWO4 core-shell structure prepared by a facile and cost-effective solution route. The core-shell structure consists of WO3 nanowire array as the core and MnWO4 nanosheets as the shell. The as-synthesized hybrid structures as the supercapacitor negative electrodes possess remarkably enhanced specific capacitance. By matching with MnO2 nanosheets as the positive electrode, a 2 V voltage asymmetric supercapacitor is assembled, which reveals an excellent rate capability with 92.11% capacity retention after 10,000 cycles. In addition, the as-obtained ASC presents outstanding cycling performance after 10,000 cycles at the working temperature of 3 °C.

Porous α-Fe2O3@C Nanowire Arrays as Flexible Supercapacitors Electrode Materials with Excellent Electrochemical Performances.

Porous α-Fe2O3 nanowire arrays coated with a layer of carbon shell have been prepared by a simple hydrothermal route. The as-synthesized products show an excellent electrochemical performance with high specific capacitance and good cycling life after 9000 cycles. A solid state asymmetric supercapacitor (ASC) with a 2 V operation voltage window has been assembled by porous α-Fe2O3/C nanowire arrays as the anode materials, and MnO2 nanosheets as the cathode materials, which gives rise to a maximum energy density of 30.625 Wh kg−1and a maximum power density of 5000 W kg−1 with an excellent cycling performance of 82% retention after 10,000 cycles.

Co3O4 nanowire@NiO nanosheet arrays for high performance asymmetric supercapacitors.

Herein, we report a simple and facile sequential hydrothermal process for the synthesis of Co3O4 nanowire@NiO nanosheet arrays (CNAs). The as-synthesized CNAs were characterized in detail using various analytical techniques, which confirmed the high crystallinity, purity, and high-density growth of these nanomaterials. From an application point of view, the as-synthesized CNAs were directly used as supercapacitor electrodes, revealing a specific capacitance of up to 2018 mF cm-2 at a current density of 2 mA cm-2. Furthermore, a flexible asymmetric supercapacitor was fabricated using the as-synthesized CNAs as the anode and activated carbon as the cathode, which revealed a specific capacitance of 134.6 mF cm-2 at a current density of 2 mA cm-2. In addition, the supercapacitor showed excellent capacity retention of 73.5% after 10 000 cycles at a current density of 10 mA cm-2.

Hierarchical Co3O4@Co9S8 nanowall structures assembled by many nanosheets for high performance asymmetric supercapacitors.

Herein, we report hierarchical Co3O4@Co9S8 nanowalls assembled by many nanosheets. The as-synthesized products are characterized in detail using various characterization methods. They can be directly used as supercapacitor electrodes with excellent electrochemical performance due to the synergy effect between Co3O4 and Co9S8. Furthermore, a flexible asymmetric supercapacitor is fabricated by using the as-synthesized Co3O4@Co9S8 structures as the cathode and the active carbon as the anode, which reveals a specific capacitance of 266.6 mF cm-2 at a current density of 4 mA cm-2. In addition, the supercapacitor shows an excellent capacity retention rate of 86.5% after 10 000 cycles at a current density of 10 mA cm-2. Finally, three supercapacitor devices connected in series can light a blue LED lamp for 5 min.