Hollow carbon nanospheres for capacitive-dominated potassium-ion storage

Carbonaceous material is considered as the most promising anode material for potassium ion batteries (KIBs) in the advantages of low price, stable physical/chemical properties, and renewable resources. However, the moderate capacity and sluggish kinetics cast a shadow over its application. Here, we synthesize multiple active sites decorated porous hollow carbon nanospheres (S/N-PHCs) by a one-step large scalable carbonization method with polypyrrole coated polystyrene and low-cost sulfur as precursors. The obtained S/N-PHCs exhibits an amorphous nanocarbon structure with high specific surface area (502.2 m(2) g(-1)) and S, N content of 9.12 and 3.14 at.%, respectively. The porous hollow nanospheres structure promotes the fully utilization of multiple active sites and a capacitive-dominated K+ storage. Consequently, the S/N-PHCs electrode delivers an ultrahigh specific capacity of 460.6 mAh g(-1) at a current density of 100 mA g(-1) with an initial Coulombic efficiency of 67.7% and excellent rate capability of 228.1 mAh g(-1) at 5000 mA g(-1). Moreover, a high reversible capacity of 249.7 mAh g(-1) can be retained over 1000 cycles at 1000 mA g(-1) (83.4% of the initial specific capacity), demonstrating a remarkable cycle stability. This work provides a scalable and environmentally friendly strategy to achieve hierarchical amorphous carbon as superior anode for KIBs.

Automated summary

In this study, multiple active sites decorated porous hollow carbon nanospheres were synthesized through a one-step large scalable carbonization method, demonstrating superior performance for potassium ion batteries.