Biomass CQDs derivate carbon as high-performance anode for K-ion battery

Carbon quantum dots (CQDs) as a multifunctional carbon nanomaterial have drawn great attention in the field of energy attribute to quantum size, various functional groups and unique physicochemical properties. In this work, the CQDs were prepared from soybean by a simple hydrothermal method, then further pyrolyzed into honeycomb carbon (HC), spherical pore carbon (SC) and bulk porous carbon (BC) with the assistance of templates, respectively. As the anode materials in potassium ion battery (PIBs), HC delivered a high specific capacity of 280.5 mAh g−1 at 0.1 A g−1 and a superior rate performance (136 mAh g−1 at 5 A g−1), ascribing to its abundant surface active sites of potassium ion storage and special structures conducive to potassium ion diffusion. This study provides an excellent anode for PIBs from a simple route to construct CQDs-derived carbon.