Sulfur-doped pomegranate-like carbon microclusters designed via facile spray-drying process: A novel anode material for potassium-ion batteries

Recent research has demonstrated increasing inclination toward employing hollow carbons featuring nanoscale amorphous structures as anodes in potassium-ion batteries. However, these amorphous structures detrimentally impact the electrode's electron and ion conductivities, leading to subpar rate performance. Additionally, integrating nanoparticles into electrodes typically yields an uneven distribution, owing to the propensity of nano- materials to readily aggregate. To address these challenges, S-doped pomegranate-like carbon microclusters (SPCMs) comprising S-doped primary hollow carbon spheres (HCSs) were synthesized via spray drying. The effects of self-assembly and S doping on the morphological structure and potassium storage performance of the HCS materials were systematically investigated through comprehensive analyses. PCMs mitigated volume expansion and imparted high conductivity and charge/discharge rates owing to short potassium-ion diffusion distances, while the self-assembled nanospheres improved slurry flow properties. Additionally, sulfur doping increased the pore size, interlayer spacing, and number of defect sites in the carbon lattice, improving electron mobility. The resulting S-PCMs exhibited exceptional potassium storage properties, particularly cycling performance (224 mA h g- 1 at the 1000th cycle). Furthermore, various electrochemical tests attributed S-PCM's enhanced potassium storage performance to the numerous active sites and increased resistance to charge transfer, improving the potassium diffusion coefficient.