Construction Of Transition Metal Chalcogenides Nano-arrays And Its Application In The Field Of Flexible Hybrid Supercapacitors

With the rapid development of the global economy,the power and energy needs of the next generation of portable and flexible electronics are increasing.As a result,there is an urgent need to develop flexible,lightweight and environment friendly energy storage devices.Among all the energy storage devices,flexible solid supercapacitors not only have high power density and long cycle life,but also have the advantages of small size,high reliability,lightweight,easy to carry,and wider operating temperature range.However,the low energy density of current supercapacitors is still an urgent problem.Generally speaking,wider voltage range and higher specific capacitance are advantageous for obtaining capacitors with high energy density.Hybrid supercapacitors combine the advantages of battery-type materials and capacitor-type materials to enable the performance of positive and negative electrodes to complement each other.Therefore,they have wider voltage window and higher specific capacitance,which can realize the demand for high energy density supercapacitors.So,hybrid supercapacitors have become the focus of current research in the field of energy.In fact,the charge storage and energy conversion of supercapacitors are closely related to electrode materials.Therefore,reasonable design and development of electrode materials with high electrochemical activity and high specific capacity are the key to achieve the high-performance supercapacitors.In the current conventional electrode materials,the transition metal compound nanoarray materials are promising electrode materials.The electrode materials do not need to add binders and conductive agent,and can make the electrode materials maximize to participate in the electrochemical reaction.Therefore,the application of transition metal compound ordered nanoarray structure electrodes to supercapacitors makes its easier to form lighter,smaller,lower cost,higher performance devices,which have a huge development prospect in future energy storage applications?flexible,light and wearable?.Based on above considerations,electrode materials with regular morphology and excellent electrochemical performance were synthesized by simple chemical liquid-phase method,such as Ni S nanowire array electrode;Ni Se₂ nanoarray electrode;and Ni₃Se₂ nanowire array electrode material.Then,these nanoarray electrodes and activated carbon/porous biomass carbon were used as positive and negative electrode materials to assemble flexible solid-state hybrid supercapacitors.The electrochemical performance of the full-cell system was studied and its practical application values was also evaluated.The specific research details are as follows:?1?The energy storage properties of high-performance solid-state supercapacitors based on Ni S nanoarrays and activated carbonNi S nanowire array materials were synthesized by one-step solvothermal method.When applied as the electrodes of supercapacitors can achieve excellent electrochemical properties.It is particularly important that solid-state hybrid supercapacitors based on Ni S nano-arrays and activated carbon can achieve the areal energy density of 0.355 m Wh cm^-2.Forthermore,the current hybrid supercapacitors can deliver the outstanding working lifetimes and the higher practical value.?2?The assembly and energy storage properties of flexible hybrid supercapacitors based on Ni Se₂ nanoarrays with high specific capacity and activated carbonWhite mushroom-like Ni Se₂ nanoarrays were synthesized by an in-situ hydrothermal process.Electrochemical tests showed that the white mushroom-like Ni Se₂ nanoarrays have higher specific capacity,lower resistance,and better cycling performance.More importantly,Ni Se₂ nanoarrays are further assembled into flexible hybrid supercapacitors with activated carbon as the counter electrodes.This hybrid energy-storage device has 33 Wh kg^-1 energy density and 90.3%capacity retention.Meanwhile,it also shows the remarkable mechanical flexibility and high commercial value.?3?The assembly of high-performance flexible hybrid supercapacitors based on the efficient matching of electrode materials with different energy-storage mechanismBattery-type Ni₃Se₂ nanoarray materials with the specific capacity of 132.4m Ah g^-1 were synthesized via solvothermal method.Using corn stalk as raw material,porous biomass carbon with high specific surface area of 2217.8 m² g^-1 and large specific capacity of 112.5 m Ah g^-1 is prepared by cross-linking and activation methods.Then,the flexible hybrid supercapacitors were assembled by using two electrode materials as positive and negative electrodes respectively.This flexible hybrid device has energy density of 38.8 Wh kg^-1,excellent mechanical flexibility and low-temperature resistance.