Nitrogen-Doped Carbon Nanotubes Derived from Metal-Organic Frameworks for Potassium-Ion Battery Anodes

To tackle the issue of the poor rate capability of graphite anodes for potassium-ion batteries (KIBs), nitrogen-doped carbon nanotubes (NCNTs) with an edge-open layer-alignment structure were synthesized using a simple and scalable approach of pyrolyzing cobalt-containing metal-organic frameworks. The unique structure enables a facile and fast intercalation of K ions. As anodes of KIBs, the NCNTs demonstrated an improved rate capability by a high capacity retention of 102 mA h g^-1 at a high current density of 2000 mA g^-1 and a good stability without evident capacity loss over 500 cycles at 2000 mA g^-1 . Our findings can help to develop highperformance anode materials for potassium-ion batteries as large-scale and low-cost energy-storage systems.