Recently, the demands for energy storage devices are highly expanding due to its worldwide utility. Present decades, the research area on energy storage devices development that uses nanoparticles (NPs) in it is interesting due to their size-dependent chemical and physical properties. The transition metal oxide (MO) and metal sulfide (MS) nanomaterials are being concentrated broadly due to extraordinary properties of optical, electrical, electronics, thermal, mechanical, and catalytic behavior. These characteristics are attributed due to their unique structures and size. The area of MS nanoparticles has wide applications such as superconductors, conversational solar energy devices, flat panel displays, fluorescence devices, electroluminescence devices, semiconductor devices, and photo-catalyst, etc., [1–3]. The two dimensional (2D) nanomaterials investigations are being done in semiconducting materials such as metal sulfides and metal oxides [4, 5]. Along with the MS family, Nickel sulfide semiconducting NPs include a potential candidate for diverse applications such as lithium-ion batteries, electrochemical supercapacitors, light-emitting diodes, photocatalysis, field-effect transistors and solar cell, etc., [3, 6–11]. Besides, various types of preparation methods are followed to prepare MS NPs with different structures and shapes (for example, sonochemical, reflex technique, sol-gel, microwave illumination, hydrothermal, and thermolysis technique) using a single source [3, 12–16]. Nickel sulfide nanoparticles have different crystalline structures, typically (NiS2, Ni9S8, Ni7S6, Ni3S2, Ni3S4, Ni6S5, and NiS) have concentrated because of their high hypothetical limits and low cost [17, 18].
At present, the two possible solutions for energy demands are available in the marketplace; they are supercapacitors and hybrid batteries. Supercapacitor gives high energy density, but storage capacitance is low; consequently, the SCs do not be utilized in gadgets that require more storage capacitance. By this way, in the current year supercapacitors have increased a lot of consideration instead of batteries. There are three kinds of supercapacitors such as (i) pseudocapacitors, (ii) EDLC (electrochemical double-layer capacitors), and (iii) hybrid capacitors [19]. Presently, SCs, as the best device for efficient power energy storage, have increased quickly expanding consideration for its powerful energy density, small size, more life cycles. SCs can be utilized in different fields, for example, hybrid storage device cars and other electric vehicles, the backup energy source in convenient electronic gadgets, and versatile hardware. Recently, Ni9S8 has standard capable electrode material in SCs. Also, it has exclusive properties like abundant oxidation and reduction activities, changing the magnetic phase, and more electrical conductivity, ecofriendly in nature, good electrochemical stability. The nickel sulfide materials are more excellent redox activity, high capacitance performance, and low cost, which are predictable to fulfill the expanding needs of the storage energy system [20–22].
Many researchers broadly concentrated on the utilization of single-source precursor-like metal complexes for the pure and perfect formation of MS with different architecture like 2D and 3D structured nanomaterials on a large scale. Moreover, single-source precursors are more stable, simple reaction conditions, and reducing by-products as well as less expensive. Arrangement of MS NPs has been broadly investigated using single-source precursors of the metal-dithiocarbamate complex [3, 7, 23–25]. Additionally, the MS materials demonstrated the great specific capacitance on the grounds, and the explanations define numerous redox states along with a variety of the progressive structure as well as pores nature of the material. The compositional MS materials with carbon-based complex give electrode material with high efficiency.
Here, Nickel dithiocarbamate [Ni(DTC)2] complex has been utilized as single-source precursor for effective Ni9S8 2D nano sheets synthesized, by using simple solvothermal technique. The Ni9S8 NSs were analyzed and confirmed with properties like phase-purity, good crystalline structure. Additionally, the prepared nanomaterials were analyzed with their electrochemical nature. Such as, cyclic voltammetry (CV), Chronopotentiometry (GCD) and electrochemical impedance spectroscopic (EIS) investigation was performed to study oxidation, reduction properties, charge-discharge mechanism and conductivity, respectively of the prepared Ni9S8 electrode materials.