Controllable Preparation Of Potassium Citrate And Its Electrochemical Energy Storage Research

With the increasing demand for fossil fuels?coal,oil,natural gas,etc.?,the resulting energy crisis and environmental pollution have become seriously.As for an urgent need to develop efficient,clean and renewable new energy sources.In order to tie in with the effective use of emerging power generation technologies,advanced energy storage technology has attracted widespread attention.Supercapacitors have many characteristics such as long cycle life,ultra-high power density,high rate performance,large specific capacity and environmental friendly,which can supplement the inadequacies of other power sources such as batteries and fuel cells.Especially in areas where power requirements are high?such as super capacitor powered buses,fast charging vehicles,etc.?,achieve prosperity achievement.K₄Nb₆O₁₇ has an ion-exchangeable layered structure which possesses two different kinds of alternating interlayer spaces,i.e.interlayers I and II,where K⁺ions are located,the interlayers are hydrated in an aqueous solution.The specific work of this paper is as follows.:?1?K₄Nb₆O₁₇ is synthesized from the top down.In this chapter,K₄Nb₆O₁₇?about 3 mm?was obtained by high-temperature solid-state reaction,and then K₄Nb₆O₁₇ nanoplates?2 nm?were obtained by stripping with n-propylamine,and finally carbon-doped.Through the exploration of different carbon-doped temperatures,a series of K₄Nb₆O₁₇-C composites have been synthesized and tested to obtain products that are optimally processed at 800°C.As a negative electrode material for a supercapacitor,K₄Nb₆O₁₇-C-800 has a specific capacitance of 330 F g^-1 at a current density of 0.5 A g^-1?three-electrode system test,electrolyte of 6 M KOH?at 100 A g^-1,the specific capacitance is 161 F g^-1,and good cycle life.At 10 A g^-1,it can maintain more than 95%of the initial specific capacitance after 10 000 charge-discharge cycles.And in asymmetric lithium-ion batteries as organic electrolytes have good performance(capacitance contribution of 84%at 1 mV s^-1).These excellent electrochemical properties benefit from its extremely thin thickness,good ion transfer rate,extremely low electrical conductivity,and the coating of porous carbon on the surface to effectively increase its specific surface area,enabling it to be charged and discharged.The electrode material and the electrolyte can be in full contact with each other,which facilitates the transport of ions and electrons.?2?Potassium niobate is synthesized from the bottom up.This chapter successfully synthesizes potassium niobate nanowire clusters?PNNWCs?from amorphous Nb₂O₅ through two simple solvothermal reactions.The SEM can observe that the material has a porous,ordered coral-like hierarchical structure.Thanks to this unique structural feature,the resulting PNNWCs exhibit excellent performance in electrochemical storage of supercapacitors(under alkaline conditions,the specific capacitance is as high as 417 F g^-1 and 175 F g^-1 when the current density is 0.5 A g^-11 and 100 A g^-11 respectively).In addition,the electrode material also exhibited significant electrochemical performance and stability at ultra-high current density(hardly any loss of capacitance was observed after 10 000 cycles at 50 A g^-1).When used in lithium-ion supercapacitors,they exhibit excellent reversibility and cycling stability.