Defect-rich N/O-co-doped porous carbon frameworks as anodes for superior potassium and sodium-ion batteries

Carbon with high electrical conductivity, chemical stability, and capability to alleviate massive volume expansion are the most promising anode materials for sodium and potassium ion batteries. Herein, we develop a defect-rich porous carbon framework (denoted as DRPCF) built with N/O-co-doped mesoporous nanosheets. The as-prepared DRPCF-2/1-700 demonstrates the largest specific surface area with the enormous pore volume and has the highest N/O heteroatom contained active defect sites. Consequently, DRPCF-2/1-700 exhibits superior pseudocapacitive behavior dominated sodium and potassium ion storage performance. As anode materials for sodium and potassium ion batteries, they exhibit high rate and long-term cyclic performance with a mass-specific capacity of 328.2 and 321.5 mAh g⁻¹ at a current density of 1 A g⁻¹ over 900 and 1200 cycles, which outperform most reported carbonaceous materials. The ex-situ Raman spectroscopy results further confirm that the filling and removing of K⁺ and Na⁺ from the site of the electrochemically active defect should be responsible for the high capacity, superior rate, and cyclic performance of DRPCF-2/1-700.