Advanced aqueous energy storage devices based on flower-like nanosheets-assembled Ni0.85Se microspheres and porous Fe2O3 nanospheres

Abstract

The design and development of novel aqueous energy storage devices with high specific energy has recently become the research hotspot. The traditional energy storage devices are severely hindered because of the relatively low specific capacity of carbon anode materials. In this work, a novel aqueous energy storage device is assembled based on flower-like nanosheets-assembled Ni0.85Se microspheres as the cathode and porous Fe2O3 nanospheres as the anode. The flower-like nanosheets-assembled Ni0.85Se microspheres are synthesized by a two-step hydrothermal method and the porous Fe2O3 nanospheres are prepared through a facile one-step ionic liquid-assisted hydrothermal method. Due to their unique structures and superior electrochemical properties, the as-fabricated Ni0.85Se//Fe2O3 asymmetric device manifests high specific energy (39.2 Wh kg−1), high specific power (8.56 kW kg−1) and good cycling stability (82.6% of capacity retention after 5000 cycles). Moreover, two asymmetric devices are connected in series and can easily light a white light-emmitting diode for more than 5 min after being charged to 3.0 V. These impressive results indicate that the rational design of cathode and anode materials for energy storage devices is vitally important, and therefore this work can provide a valuable reference for the design and fabrication of novel energy storage devices with high specific energy and high specific power.