Boosting the potassium storage performance of carbon anode via integration of adsorption-intercalation hybrid mechanisms

Abstract

Abstract Graphitic carbon has been drawn extensive attention as an anode for Potassium-ion battery (KIB) because it is favorable for K-intercalation. However, the application of graphitic carbon anode for KIB is prevented by the poor cyclability and poor rate capability, resulting from the huge volume expansion and structural collapse after repeat charge/discharge. Herein, by advantageous functional integration of adsorption-intercalation potassium storage mechanisms, we design flexible nitrogen (N) and oxygen (O) dual-doped carbon coated graphene foam films (denoted as NOC@GF) that realizes unprecedented electrochemical performance for KIBs. Such advanced architecture can release the respective advantages of graphitic carbon with high electrical conductivity stability and favorable of K-intercalation, and amorphous heteroatoms doping carbon layers with abundant active sites for potassium adsorption storage. It delivers high reversible capacity (319 mA h/g at 0.1 A/g with a capacity retention of 94.9% after 550 cycles), long cycling stability (281 mA h/g at 1 A/g with a capacity retention of 98.1% after 5500 cycles), and excellent rate capability (123 mA h/g at 5.0 A/g). And density functional theory (DFT) calculations prove that N and O doping sites are benefit to facilitating K ion adsorption and the graphitic carbon promotes K-ion intercalation storage.