Construction of Heterostructure Nickel Sulfoselenide Arrays for Advanced Potassium-Ion Hybrid Capacitors

Transition metal compounds are being extensive studied in K-ion hybrids capacitors (KIHCs) owing to their abundant resource and ultrahigh theoretical capacity. However, their poor cycling lifespan and rate capability as vulnerable structures is the major bottleneck for future development. Here the design and construction a heterostructure Nickel sulfoselenide arrays (NiSSe) with large-scale high ordering and large interval spacing are reported. Benefiting from the synergistic effect of the inner Cu nanoarray with superior conductivity and outer NiSSe layer with massive active sites, the heterostructure NiSSe exhibits a superior K-ion storage capability with a reversible high potassium ion storage (585 mAh g^-1 at 0.2 A g^-1) and excellent cycle stability. As expected, the KIHCs assembled with NiSSe anode and a N/O co-doped carbon nanowire array (NOC) cathode deliver a high-energy density and power density (156.2 Wh kg^-1 and 20 kW kg^-1) as well as excellent cycling lifespan. The first-principle calculations reveal that NiSSe have high ionic/electronic conductivity characteristics and low diffusion barriers for K⁺-intercalation. This core-shell nanoarray strategy may open up a novel avenue for transition metal compounds application in electrochemical storage, conversion, and beyond.