Improved performance of a CoTe//AC asymmetric supercapacitor using a redox additive aqueous electrolyte

Abstract

The performance of an ASC with CoTe as the positive electrode can be enhanced by introducing redox additive K4Fe(CN)6 into the alkaline electrolyte.

Hydrothermal synthesis of cobalt telluride nanorods for a high performance hybrid asymmetric supercapacitor

“…The fabricated hybrid ASC cell with CoTe NRs and OPAA electrode materials as the positive and negative electrodes shows good discharge reversibility and outstanding cycle stability, respectively. These electrochemical stability values are higher than the recently reported materials, such as CoTekAC (90% for 5000 cycles), 21 CoTekAC (80% for 3000 cycles), 22 NiTe (81% for 3000 cycles), 25 1T-MoTe 2 (87% for 5000 cycles). 26 The Ragone plot is a typical tool to evaluate the supercapacitor device with other types of energy storage devices in terms of their energy and power density values.…”

“…Both electrode materials have a strong pair of redox peaks during the CV analysis, which resulted from the following surface reversible redox reaction between Co 2+ and Te for CoTe NRs and Te NRs in the presence of OH À ions, respectively. The possible redox reactions in the Te and CoTe electrodes can be described as follows: 22,45 Te + OH À # TeOH + e À…”

“…For instance, Ye et al synthesized CoTekAC ASC that delivered an energy density of 67 W h kg À1 for the pristine electrolyte. 22 Quan et al fabricated a CuS-CNTs@NFkAC ASC showing the specic capacitance of 164 F g À1 at a current density of 0.5 A g À1 with an energy density of 22.14 W h kg À1 . 48 The assembled Ni 3 NkPRPC-1K ASC possessing a high energy and power density of 30.9 W h kg À1 and 412 W kg À1 , respectively, have been reported by Peng et al 49 Wang et al constructed a NiCo LDHkAC ASC displaying a specic capacitance of 58 F g À1 at the current density of 1 A g À1 with an energy and power density of 18 W h kg À1 and 750 W kg À1 , respectively.…”

“…The EDLC as a negative electrode (power source) uses materials like activated carbon, carbon nanotubes and graphene because of their high surface area, high stability and high electrical conductivity. 21,22 In this scenario, metal chalcogenides are a new type of electrode material for the electrochemical supercapacitor. In the metal chalcogenides, the metal ion undergoes fast surface redox reactions associated with different oxidations of the transition metal ion.…”

“…CoTe nanowires can extend their potential voltage to 1.6 V and give energy and power density values of 32.9 W h kg À1 and 800.27 W kg À1 , respectively, even aer 5000 cycles at the current density (5 A g À1 ) with an initial capacitance of 90.5%, as reported by Xiao et al 21 Ye et al synthesized a CoTekAC asymmetric supercapacitor electrode grown on carbon ber paper by hydrothermal method, which showed a specic capacitance of 120 C g À1 with an energy density of 67.0 W h kg À1 . 22 Cao et al reported on Te NWs arrays with high conductivity grown on a exible carbon ber to fabricate hybrid Te/Au/MnO 2 core-shell nanostructures as a supercapacitor with 97% capacitance retention for 1000 cycles. 24 Zhou et al prepared NiTe rods as a positive electrode material for an asymmetric supercapacitor (ASC) with a specic capacitance of 804 F g À1 (current density 5 A g À1 ) and 91% of capacitance retention for 1000 cycles.…”