N-doped hollow carbon spheres as a high-performance anode for potassium-based dual-ion battery

Potassium-based dual-ion batteries (KDIBs) have become an alternative product for lithium-ion batteries owing to their high voltage, environmental friendliness and low cost. In this paper, nitrogen-doped activated hollow carbon nanospheres (N-AHCSs) with high specific surface area, porous structures and large interlayer spacing were prepared as anodes for KDIBs. The N-AHCSs are characterized by large interlayer spacing, hollow spheres structures and doping nitrogen. The large interlayer spacing and hollow structures are conducive to intercalation/deintercalation and diffusion behaviors of K ion. And nitrogen doping in carbon structures can provide sufficient K ion active sites. Therefore, the KDIBs composed of expanded graphite cathode and N-AHCSs anode deliver impressive specific capacity of 89.8 mAh g−1 at 0.1 A g−1 and super rate performance of 72.4 mAh g−1 at 1 A g−1 after ultra-long 2000 cycles. The results indicate that the N-AHCSs might be an excellent candidate for KDIBs anodes.