Synthesis of a 3D free standing crystalline NiSex matrix for electrochemical energy storage applications

Abstract

The electrochemical performance for energy storage of three-dimensional (3D) self-supported heterogeneous NiSe_x cubic-orthorhombic nanocrystals grown by a facile one-step chemical vapour deposition (CVD) approach on Ni foam substrates has been explored. NiSe_x shows a high specific capacitance of 1333 F g⁻¹ with ultra-high energy (105 W h kg⁻¹) and power (54 kW kg⁻¹) densities. Furthermore, by integrating the as-grown NiSe_x as the anode and reduced graphene oxide as the cathode, a hybrid supercapacitor (HSC) prototype with a coin cell configuration has been fabricated. The device shows better capacitance (40 F g⁻¹) with high energy (22 W h kg⁻¹) and power (5.8 kW kg⁻¹) densities and robust cycling durability (∼88% capacitance retention after 10 000 repeated cycles). For practical reliability of the as-fabricated HSC, a red LED has been illuminated by connecting it with two charged coin cells. These outstanding performances of the HSC prove to be promising for applications in high energy storage systems.