P/N Co‐doped Carbon Nanotubes with Dominated Capacity‐controlled Absorption Effect Enabling Superior Potassium Storage

Abstract

AbstractCarbonaceous materials are considered to be the most promising anode materials of Potassium‐ion batteries (PIBs). However, for most carbon‐based PIBs anode materials reported so far, they usually deliver low reversible capacities, insufficient cycle life and poor rate capability. In this work, we report a novel P/N co‐doped carbon nanotube (PNCNTs) material as the anode material for PIBs. The material with fully exposed active edges and open fast ion/electron transfer structure can effectively shorten the K+ transfer distance. Furthermore, the P/N co‐doping provides abundant electrochemical active adsorption sites and extended interlayer spacing, which facilitates the rapid insertion/removal of K+, increases the surface charge capacity and maintains the structural stability of the electrode material. As expected, when used as the anode material for PIBs, PNCNTs exhibited a high specific capacity (612.2 mA h g−1 at 100 mA g−1), excellent rate capability (190, 183 and 165 mA h g−1 at 0.5, 1.0, and 2.0 A g−1 after 500 cycles, respectively) as well as remarkable long‐term cycling stability (162 mA h g−1 at 2.0 A g−1 after 1400 cycles). Through further kinetic analysis and a simple first‐principles calculation, we revealed the dominated capacity‐controlled absorption mechanism of potassium storage in PNCNTs.