Nitrogen-Doping-Induced High-Performance Carbon Nanofiber Anodes for Potassium-Ion Storage

Due to the abundant supply of potassium, potassium ion batteries (PIBs) are considered as a promising alternative battery system to lithium-ion batteries (LIBs). Carbonaceous materials are the preferred anode materials for these batteries. However, the electrochemical performance of carbonaceous anode materials is still unsatisfactory, hindering the development of PIBs. In this work, nitrogen-doped carbon nanofibers (N-CNFs) were synthesized by the calcination of bacterial cellulose with urea acting as a nitrogen source. When employed as an anode material for PIBs, the N-CNFs exhibit a stable specific capacity of 205 mA h g-1 at 0.2 C after 250 cycles and an outstanding rate capability of 149.7 mA h g-1 at 5.0 C. The N-doped structure can facilitate the K+ and electronic conductivity, which will effectively enhance electrochemical performance of the electrode. In addition, ex situ X-ray photoelectron spectroscopy and X-ray diffractometry pattern analyses illustrate the reversible insertion of K+ in the N-CNF electrode.