Preparation and electrochemical properties of NiCo2 S4/liquefied wood carbon aerogel composites
The rapid growths of population and economic activities have led to several challenges,including,energy shortages and environmental pollution.Therefore,efficient storage and conversion of clean energy such as solar and wind energy are particularly important.Due to their higher energy density than traditional capacitors and better power density than secondary batteries,supercapacitors are considered ideal energy storage devices.As a key component of supercapacitors,electrode materials greatly affect the overall performance of supercapacitor.In view of the defects of low specific capacitance of carbon aerogel and poor rate performance and cycle stability of metal sulfides,and in order to realize the value-added utilization of wood biomass resources,the NiCo2S4/liquefied wood carbon aerogel(NiCo2S4-CA)composite electrode material was prepared by in-situ loading NiCo2 S4 onto skeleton surface of carbon aerogel(CA)synthesized by gel,carbonization and activation with liquefied wood as precursor material via two-step hydro-thermal method.The phase structure and surface morphology of NiCo2 S4-CA were characterized by the scanning elec-tron microscope(SEM),nitrogen adsorption-desorption experiment,Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).At the same time,the electrochemical properties were studied by cyclic voltammetry(CV),galvanostatic charge-discharge(GCD)and electrochemical im-pedance spectroscopy(EIS),and the charge storage mechanism was explored as well.The results showed that the NiCo2 S4 nanoparticles were anchored on the surface of liquefied wood carbon aerogel with coral network structure,forming a multi-level pore structure with abundant pores.The introduction of CA was beneficial to the good dispersion of NiCo2 S4,alleviating its agglomeration problem without changing the original crystal structure of NiCo2 S4.As an e-lectrode material for supercapacitors,the NiCo2 S4-CA3 composite material exhibited remarkable electrochemical per-formance,achieving a maximum specific capacity of 1 040.2 F/g at a current density of 1 A/g,which was signifi-cantly improved compared to NiCo2 S4.It also had a smaller equivalent resistance(about 1.01 Ω)and good cycling stability.After 2 000 constant current charging and discharging cycles at a current density of 10 A/g,it maintained 56.61%of the initial specific capacity,which was better than 47.33%of NiCo2 S4.Moreover,at ultra-high current density in 20 A/g,the capacitance retention of NiCo2 S4-CA3 was up to 74.34%,which was superior to NiCo2 S4(a-bout 57.65%).The charge storage kinetics of the composite electrode material revealed that the electrochemical processes were controlled by a combination of surface capacitance control and diffusion control processes.The synthe-sis process is simple and cost-effective,and NiCo2 S4-CA3 as an electrode material for supercapacitors has extremely broad application prospects in fields requiring high capacity and high current density.
万方数据
维普
