Novel fabrication of N-doped hierarchically porous carbon with exceptional potassium storage properties

Potassium-ion batteries (PIBs) are an emerging energy storage technology for low cost and large scale applications. However, due to the larger K ions it suffers insufficient cycle life and poor rate capability. In this paper, these problems are surmounted by using N-doped porous carbon (NPC) anodes. Excellent electrochemical performance was demonstrated with a high reversible capacity of 296.8 mA h g−1 after 100 cycles at a current density of 50 mA g−1. The superior performance is mainly ascribed to well-defined pore structure and high nitrogen content. The unique porous structure can effectively alleviate the volume expansion induced by the insertion of large K ions. Moreover, nitrogen doping can generate different types of defects and vacancies, thereby providing more electroactive sites. Given the abundance and universal distribution of potassium in the Earth's crust, the encouraging results make NPC a promising candidate for KIBs anodes.