Preparation And Supercapacitor's Properties Of Hierarchical FeCo₂S₄ Array

With the vigorous development of the economy in today's society,the non-renewable energy on earth has gradually dried up.Supercapacitor is a new type of energy storage device,which provides a new way to solve this problem.At present,many emerging supercapacitor electrodes are slowly appearing.Among them,binary transition metal sulfides have attracted widespread attention due to their rich redox activity and excellent electrical conductivity.FeCo₂S₄ has two kinds of metal ions with many valence states which can enrich redox reactions.In order to improve the performance of FeCo₂S₄ supercapacitor,this paper mainly carried out the following two aspects.The details are as follows:?1?Fe-Co nanosheets arrays were synthesized by hydrothermal method,and then annealed to obtain FeCo₂O₄ nanosheets arrays which were further vulcanized to obtain hierarchical nanosheets-anchored-on-microsheets FeCo₂S₄ array.The FeCo₂S₄ electrode provides high specific capacitance of 2488.50 F g^-1(7.66 F cm^-2)at 5 mA cm^-2,and a high level of cycle stability of 95.67%retention after 5000 cycles.The FeCo₂S₄//activated carbon?AC?device delivers the maximal energy density of 44.89 W h kg^-1 and the maximal power density of 4015.56 W kg^-1.This work shows that the hierarchical FeCo₂S₄nanosheets array has a bright future in the practical application of electrochemical energy storage.?2?In order to further improve the performance of supercapacitor,the hierarchical FeCo₂S₄ nanosheets array was immersed in Na BH₄ solution for reduction treatment.The electrochemical performance of the R-FeCo2S4 was significantly improved,which is due to the large number of defects as result of NaBH₄ treatment.For the R-?H₂O?-FeCo₂S₄electrode,specific capacitance is 6.29 F cm^-2 at 5 mA cm^-2,the capacity retention rate after 5000 cycles is 92.60%.The R-?H₂O?-FeCo₂S₄//AC device delivers the maximal energy density of 57.88 W h kg^-1 and the maximal power density of 4040.33 W kg^-1.