CoS2/Ni3S4 − N − C heterostructured electrode materials derived from Prussian-blue analogs for supercapacitors

Prussian blue analogues (PBAs) have the advantages of dependable electrochemical performance and long service life when used as energy storage materials because of their face-centered cubic structure. In this case, the appropriate metal sulfide derivatives were created using NiCo prussian blue analogue nano units as a precursor, which took on the precursor's structural traits. More reaction sites are exposed by this distinctive structural design, and a little quantity of nitrogen-doped carbon is produced, which improves charge transfer. The box-like structure has a buffer effect on the stress of the active material during charging and discharging, and the heterostructure of mixed metal sulfides and nitrogen-doped carbon composite cubic can both significantly increase the electrode's electrochemical capacitance and cycling stability. The CoS2/Ni3S4–N–C offers a capacitance of 817C g−1 at 3 A g−1 and 556C g−1 at 20 A g−1. The CoS2/Ni3S4–N–C electrode also has outstanding cycle stability (98.2 % capacitance retention after 10,000 cycles). An asymmetric supercapacitor (ASC) device made of CoS2/Ni3S4–N–C with activated carbon electrodes exhibits exceptional cycle stability. With a retention rate of 103.7 % after 10,000 cycles at 10 A g−1 and an energy density of 40 Wh kg−1. Using density functional theory (DFT), the electron characteristics of Co2NiO4 and CoS2/Ni3S4–N–C are compared. CoS2/Ni3S4–N–C detected more state densities at the Fermi level, which causes more charge to accumulate. This shows that the heterojunction's electron conductivity is significantly greater than the oxide's, and ultimately leads to quicker reaction kinetics.