Plasma Synthesis Of NiSe₂ Ultrathin Porous Nanosheets For Supercapacitor

Among many energy storage devices,supercapacitors are favored for their high power density and long cycle life.However,at present,the commercialized electrode materials for supercapacitors are mainly carbon-based materials.Because of their small specific capacitance,it is urgent to develop advanced electrode materials with high conductivity and specific capacitance.Two dimensional nanomaterials have larger specific surface area and are favorable for electrolyte ion transport.Pore structure can shorten the electrolyte diffusion distance and increase the contact area between electrolyte and electrode materials.In addition,anion defects can improve capacitance performance by increasing conductivity and active sites of materials.Therefore,in order to obtain excellent electrode materials,we designed and synthesized ultrathin two-dimensional nanosheets with abundant pore and anion defects and studied their supercapacitor performance.In this paper,NiSe₂ with good conductivity is chosen as model material.Layered NiSe₂-butylamine inorganic-organic hybrid precursors were synthesized by solvothermal method.The ultrathin porous NiSe₂nanosheets with selenium defect(NiSe₂PNS_vac)were prepared by plasma dry exfoliation.NiSe₂PNS_vacwith a thickness of 1.4 nm were identified by a series of characterization methods,and the existence of selenium defects was confirmed.The electrochemical properties of NiSe₂PNS_vacas electrode material for supercapacitors were studied by cyclic voltammetry,galvanostatic charge-discharged and AC impedance method.The results show that the specific capacitance of NiSe₂PNS_vacis 466 F g^-1in 1 M KOH electrolyte at the current density of 3 A g^-1,which is much higher than that of NiSe₂ultrathin nanosheets(328 F g^-1)and NiSe₂particles(251 F g^-1).After 1000 cycles,the specific capacitance of NiSe₂PNS_vacis well maintained,indicating its high cycle stability.NiSe₂PNS_vacexhibits superior supercapacitor performance with its unique morphological advantages,such as higher conductivity,larger specific surface area and shorter electrolyte diffusion distance.This opens up a new way to design and fabricate high performance electrode materials for supercapacitors.