FeS₂ Nanoparticles Encapsulated in N/S-Doped Hollow Carbon Spheres as Anode Materials for Potassium-Ion Batteries

As the most competitive candidate to lithium-ion batteries, potassium-ion batteries (PIBs) have gained widespread attention for next-generation power storage devices owing to their superior performance and economical price. However, the electrode materials of PIBs have been suffering from a huge volume expansion caused by the large radius of K+ during potassiation/depotassiation, which leads to poor cyclic stability and rate capability. Herein, FeS2 nanoparticles anchored on the inner wall of N/S-doped hollow carbon spheres (FeS2@HCS) have been elaborately designed and fabricated by a scalable electrospray and template method. The FeS2@HCS anode exhibits a remarkable capacity of 425 mAh g–1 at 100 mA g–1 after 100 cycles, accompanied by a pimping capacity fading of 0.05% per cycle and a superior rate capacity of 302 mAh g–1 at 2.0 A g–1. Such outstanding electrochemical properties could be ascribed to the distinct microstructure of FeS2 nanoparticles anchored on the inner wall of hollow carbon spheres and the protective N/S-doped carbon shell. This work not only furnishes a convenient and scalable way to obtain high-powered electrodes for PIBs but also offers a facile way to enhance the charge transportation kinetics of yolk–shell-structured composites.