Honeycomb hard carbon derived from carbon quantum dots as anode material for K-ion batteries

Abstract

Abstract Potassium-ion battery (PIB) is a promising candidate in grid energy storage field because of the abundant potassium resource and its low cost. More efforts should be made to research anode material with long cycling performance due to the fading potassium capacity of graphite. Honeycomb hard carbon (HHC) with uniform pore structure and weakly ordered turbostratic domains was successfully prepared from carbon quantum dots (CQDs) through the calcination with the assistance of SiO2 nanospheres. As anode material for PIBs, HHC delivered a high specific capacity of 195.3 mA h g−1 and 67.43% capacity retention after 150 cycles at a current density of 0.1 A g−1. The electrochemical behaviors of HHC electrode were investigated in detail by electrochemical impedance spectroscopy (EIS) at various voltages and calculation of capacitive contribution, exhibiting favorable potassium storage property.