Optimizing the Interlayer Spacing of Heteroatom-Doped Carbon Nanofibers toward Ultrahigh Potassium-Storage Performances

Precise control over the interlayer spacing for K+ intercalation is an effective approach to boost the potassium-storage performances in carbonaceous materials. Herein, we first found that the optimal interlayer spacing for K+ intercalation is around 0.38 nm for N, O codoped carbon nanofibers (NOCNs), displaying a reversible capacity of 627 mAh g(-1) at 0.1 A g(-1) after 200 cycles, excellent rate capability (123 mAh g(-1) at 20 A g(-1)), and ultrastable cycling stability (262 mAh g(-1) at 5 A g(-1) after 10 000 cycles). Such good potassium-storage performances have never been reported in carbonaceous materials. The theoretical calculations and electrochemical studies reveal that the optimal interlayer spacing and N, O heteroatom-induced active sites work together to provide an intercalation-adsorption mechanism for storing K+ in carbonaceous materials. This work facilitates the understanding of the role of the critical interlayer spacing for K+ intercalation in carbonaceous materials.

Automated summary

The optimal interlayer spacing of around 0.38 nm for N, O codoped carbon nanofibers was found to enhance the potassium-storage performances significantly, providing reversible capacity of 627 mAh g(-1) after 200 cycles, excellent rate capability, and ultrastable cycling stability. The study also revealed the interplay between optimal interlayer spacing and active sites induced by N, O heteroatoms in facilitating the intercalation-adsorption mechanism for storing K+ in carbonaceous materials.