Nitrogen and phosphorus dual-doped porous carbons for high-rate potassium ion batteries

Pitch-based porous carbons with the abundant resources and high conductivity have potential advantages as potassium-ion battery anode materials. However, they suffer from small interlayer distance and rare potassium storage sites. Herein, nitrogen and phosphorus dual-doped coal tar pitch-based porous carbons (NPPC) was prepared in one-step carbonization using ammonium polyphosphate as N and P source and studied as the anodes for the potassium ion batteries. NPPC delivers a high capacity retention of 81.8% over 400 cycles at 1.0 A g−1. When the current density is raised to 10 A g−1, it can still retain a reversible capacity of 126 mAh g−1. The effects of carbonation temperature and ratio of ammonium polyphosphate to coal tar pitch on nitrogen and phosphorus doping contents were investigated by in situ Fourier transform infrared and synchronous thermal analysis. This work may shed light on the design of advanced potassium-ion battery by employing heteroatom doped functionalized soft carbons.