Construction of CoS2 nanoparticles embedded in well-structured carbon nanocubes for high-performance potassium-ion half/full batteries

Metal sulfides have been widely investigated as promising electrode materials for potassium-ion batteries (PIBs) due to their high theoretical capacities. However, the practical application of metal sulfides in PIBs is still hindered by their intrinsic shortcomings of low conductivity and severe volume changes during the potassiation/depotassiation process. Herein, a simple template-based two-step annealing strategy is proposed to impregnate CoS2 nanoparticles in the well-structured carbon nanocubes (denoted CoS2/CNCs) as an advanced anode material for PIBs. The ex-situ XRD measurements reveal the K+ storage mechanism in CoS2/CNCs. Benefiting from the unique structures, including abundant active interfacial sites, high electronic conductivity, and significantly alleviated volume variation, CoS2/CNCs present a high specific capacity (537.3 mAh g−1 at 0.1 A g−1), good cycling stability (322.4 mAh g−1 at 0.5 A g−1 after 300 cycles), and excellent rate capability (153.1 mAh g−1 at 5 A g−1). Moreover, the obtained nanocomposite shows superior potassium storage properties in K-ion full cells when it is coupled with a KVPO4F cathode.