A honeycomb-like nitrogen-doped carbon as high-performance anode for potassium-ion batteries

Abstract

Potassium-ion batteries (PIBs) have caused great concern owing to their low cost and the reserve-abundance of potassium, but a critical limitation in PIBs anodes is the low capacity for efficient intercalation/de-intercalation of K ions with a larger size. Herein, we successfully synthesize a nitrogen-doped carbon with a honeycomb architecture (cellular N-C) via directed growth of metal-organic frameworks (MOFs) on the surfaces of LDHs nanosheets followed by the pyrolysis and acid-etching processes. The resulting cellular N-C material exhibits promising PIBs anode activity, which is superior to the N-doped carbon (N-C) derived directly from MOFs. Through the structure design, compared with the N-C, the cellular N-C has the characteristics of finely controlled honeycomb-like morphology with higher specific surface area, well-distributed hierarchical micro/meso/macro-pores, and expanded interlayer distance. These features can greatly facilitate the K+ diffusion kinetics and make the electrode materials accommodate more K ions. Therefore, the cellular N-C electrode can deliver outstanding rate capability up to 10 A g−1 and great cycling performance at 1 A g−1 over 2000 cycles (143 mAh g−1).