Nanostructure selenium compounds as pseudocapacitive electrodes for high-performance asymmetric supercapacitor

Abstract

The electrochemical performance of an energy conversion and storage device like the supercapacitor mainly depends on the microstructure and morphology of the electrodes. In this paper, to improve the capacitance performance of the supercapacitor, the all-pseudocapacitive electrodes of lamella-like Bi18SeO29/BiSe as the negative electrode and flower-like Co0.85Se nanosheets as the positive electrode are synthesized by using a facile low-temperature one-step hydrothermal method. The microstructures and morphology of the electrode materials are carefully characterized, and the capacitance performances are also tested. The Bi18SeO29/BiSe and Co0.85Se have high specific capacitance (471.3 F g–1 and 255 F g–1 at 0.5 A g–1), high conductivity, outstanding cycling stability, as well as good rate capability. The assembled asymmetric supercapacitor completely based on the pseudocapacitive electrodes exhibits outstanding cycling stability (about 93% capacitance retention after 5000 cycles). Moreover, the devices exhibit high energy density of 24.2 Wh kg–1 at a power density of 871.2 W kg–1 in the voltage window of 0–1.6 V with 2 M KOH solution.

Asymmetric polyhedron structured NiSe2@MoSe2 device for use as a supercapacitor

“…3b reveals the existence of the two bands 238 cm -1 and 287 cm -1 correspondingly. 238 cm -1 revealed A 1g mode; 287 cm -1 explored E 1 2g mode [22,23]. Hence, the peaks appeared at 147 and 238 cm -1 corresponds to configuration of elemental selenium Raman curves of NiSe 2 [24].…”

“…Besides, polyhedron structured NMS hydrolyzed for 18h in lowest frequency region with R s (0.66 Ω) [30]. The lower equivalent series resistance altogether represent that the polyhedron shaped NMS hydrolyzed for 18 h is more favorable as an active material in contact with the electrolyte [31]. The high conductivity may be a factor deciding the high-rate capacitance.…”

Graphene oxide selenium nanorod composite as a stable electrode material for energy storage devices

“…The difference in voltage potential (anode peaks) at the highest (100 mV) and lowest (20 mV) scan rates is only 0.04 V, while a potential difference of only 0.02 V is observed for the corresponding cathode peaks, indicating excellent stability of the rGO-Se electrode material. The slight shift in the positions of the peaks at high voltage may be the result of relatively poor penetration of electrolyte into the electrode material, and therefore, a smaller fraction of the active sites would interact with the ions (Ma et al 2018). Also, the corresponding redox peaks persist at the highest scan rate, which demonstrates that the rGO-Se material possesses a better rate capability (Zhang et al 2016).…”

“…The EIS spectra are comprised of two parts in different frequencies regions. A small arc (semicircle) as observed in the high-frequency area indicates the charge transfer resistance (R ct ) at the electrolyte/electrode interface and the inclined line (in low-frequency area) represents the Warburg impedance (Z w ) caused by diffusion process (Ma et al 2018). The smaller the radius of the arc, the smaller is the resistance in an electrochemical reaction, and our data show that GO-Se electrode has a good charge transfer property with a low resistance even after 1000 cycles (Wang et al 2016;Fu et al 2015).…”

Applications of MxSey (M = Fe, Co, Ni) and Their Composites in Electrochemical Energy Storage and Conversion

“…Zhu et al[73] applied a 3D interconnected ultrathin CoSe nanosheet synthesized by the hydrothermal method to the field of SCs for the first time. Ma et al[74] synthesized sheet-like Bi 18 SeO 29 /BiSe and flower-like Co 0.85 Se nanosheets as the negative and positive electrodes of the full tantalum capacitor using a lowtemperature one-step hydrothermal method. The electrochemical performance test of the SC device assembled with Bi 18 SeO 29 /BiSe and Co 0.85 Se shows that it has a high specific capacitance (471.3 and 255 F g −1 at 0.5 A g −1 )…”