Free-Standing Nitrogen-Doped Cup-Stacked Carbon Nanotube Mats for Potassium-Ion Battery Anodes

Free-standing nitrogen-doped cup-stacked carbon nanotube (NCSCNT) mats were synthesized and tested as anodes for potassium-ion batteries (KIBs). The edge-open structure character of the NCSCNTs allows a facile insertion of K + ions into the carbon nanotubes. Combined with the nanosized feature and interconnected flexible structure, the NCSCNTs demonstrate impressive electrochemical performance with a reversible capacity of 323 mA h/g and a markedly improved rate capability retaining 75 mA h/g even at 1000 mA/g. Additionally, the free-standing NCSCNT mat electrodes eliminate the utilization of nonactive components of binders and conductive agents during the battery assembly and thereby significantly enhance the total specific capacity of the electrodes.