Synthesis of nickel selenide thin films for high performance all-solid-state asymmetric supercapacitors

Abstract

Supercapacitors (SCs) have attracted considerable attention because they possess fast dynamic response, excellent charge-discharge efficiency and superior cycling stability. In addition, SCs can also provide instantaneously a higher power density than batteries and higher energy density than conventional dielectric capacitors [1,2]. Therefore, SCs were widely used in portable electronics, power back-up, electrical vehicles and other electronic devices for the purpose of power enhancement. In recent years, the studies of energy storage devices were concentrated on all-solid-state (ASS) asymmetric SCs, because they are safer with no risk of the leakage of electrolyte [3,4]. Moreover, the asymmetric design can widen the operation voltage window and further improve the energy density of the devices.Electrode active materials are key component to fabricate high performances SCs. Generally, the active materials can be divided into two types based on different electron storage mechanisms: One family, traditional electrical double layered capacitors (EDLCs), such as active carbon (AC) [5], carbon nanotubes (CNT) [6,7], graphene or doped graphene [8,9], which store energy by accumulation of charges in the electrical double layer near the electrode/electrolyte interface. They are very stable during the charge/discharge (CD) process but suffer relatively low specific capacitance. The other family is electrochemical capacitor, which store energy via Faradaic redox reaction at electrode surface, such as NiO [10], Co3O4 [11,12], MnO2 [13-15], NiCo2O4 [16][17][18], NiCoS [19][20][21][22][23] and metalorganic frameworks (MOFs) [24,25], these electroactive materials possess high theoretical capacitance, whereas they lack of mechanical properties and electrical conductivity.Metal selenides have received considerable attention due to its enormous applications in the fields of optics, photocatalysis, and sensor [26][27][28][29]. Compared with the metal oxides, transition metal selenides exhibit much enhanced electrical conductivity due to the anion exchange providing smaller bandgap [30]. In addition, the substitution of oxygen with selenium could create more flexible structure because the electronegativity of selenide is lower than that of oxide. Some metal selenides, such as hierarchical GeSe

Optimized Synthesis of Nanostructured Trimetallic Mn–V–Fe Selenides with Battery-Type Behavior for High-Performance Hybrid Supercapacitors

“…In addition, Raj and Rout synthesized manganese-doped 2D vanadium selenide nanosheets as a positive pole and red phosphorus as a negative pole, providing 250 F g –1 at 1 A g –1 with an ED of 21.3 Wh kg –1 and a 95% capacitance retention after 5000 cycles. In addition, Li et al fabricated a nickel selenide//activated carbon solid-state ASC device, which delivered an areal capacitance of 27.0 mF cm –2 with volumetric power and energy densities of 33.35 mW cm –3 and 0.26 mWh cm –3 , respectively. Moreover, Javed et al prepared a symmetric supercapacitor from single-phase hierarchical manganese selenide (α-MnSe) microflowers.…”

Degradation of Methylene Blue by Hot Electrons Transfer in SnSe

“…Instead, there are temperature differences almost everywhere, and thermoelectric materials provide the feasibility of using this waste heat from differences in temperature. [ 19 ] Therefore, thermoelectric materials can be selected as thermal catalysts to degrade dye‐contained wastewater, and those with high Seebeck coefficient should be selected to generate high voltage and thus achieve high thermal catalytic efficiency. In this work, SnSe was selected as a thermal catalyst to degrade wastewater.…”

Phase-Dependent Energy Storage Performance of the NixSey Polymorphs for Supercapacitor-Battery Hybrid Devices

“…7−21 For the elements of the oxygen family, the metallic characteristic increases whereas electronegativity and ionization energy decrease while progressing down the group. 22,23 Thus, although transitionmetal selenides (TMSe) have physicochemical properties similar to those of metal oxides and sulfides, they exhibit better metallic properties (e.g., a higher electrical conductivity) and so can be used in advanced energy storage devices. The high electrical conductivity of TMSe results from the covalent character of the metal−selenium connections, which is substantially different from the ionic nature of the metal− oxygen bonds in metal oxides.…”

“…Transition-metal chalcogenides (most often, metal sulfides/selenides/tellurides), notably in the form of nanostructures, have been a hot topic of study in recent years due to their unique multiple oxidation states, reversible Faradaic reactions, and high theoretical specific capacities. − For the elements of the oxygen family, the metallic characteristic increases whereas electronegativity and ionization energy decrease while progressing down the group. , Thus, although transition-metal selenides (TMSe) have physicochemical properties similar to those of metal oxides and sulfides, they exhibit better metallic properties (e.g., a higher electrical conductivity) and so can be used in advanced energy storage devices. The high electrical conductivity of TMSe results from the covalent character of the metal–selenium connections, which is substantially different from the ionic nature of the metal–oxygen bonds in metal oxides. , This property stems from the selenium ions that have d-orbitals of accessible energy, whereas oxygen and sulfur anions do not, and this leads to wide valence bands and, hence, narrower band gaps compared to those of the corresponding oxides/sulfides .…”