Controlled Nitrogen Doping in Crumpled Graphene for Improved Alkali Metal-Ion Storage under Low-Temperature Conditions

The significant performance decay in conventional graphite anodes under low-temperature conditions is attributed to the slow diffusion of alkali metal ions, requiring new strategies to enhance the charge storage kinetics at low temperatures. Here, nitrogen (N)-doped defective crumpled graphene (NCG) is employed as a promising anode to enable stable low-temperature operation of alkali metal-ion storage by exploiting the surface-controlled charge storage mechanisms. At a low temperature of -40 degrees C, the NCG anodes maintain high capacities of approximate to 172 mAh g(-1) for lithium (Li)-ion, approximate to 107 mAh g(-1) for sodium (Na)-ion, and approximate to 118 mAh g(-1) for potassium (K)-ion at 0.01 A g(-1) with outstanding rate-capability and cycling stability. A combination of density functional theory (DFT) and electrochemical analysis further reveals the role of the N-functional groups and defect sites in improving the utilization of the surface-controlled charge storage mechanisms. In addition, the full cell with the NCG anode and a LiFePO4 cathode shows a high capacity of approximate to 73 mAh g(-1) at 0.5 degrees C even at -40 degrees C. The results highlight the importance of utilizing the surface-controlled charge storage mechanisms with controlled defect structures and functional groups on the carbon surface to improve the charge storage performance of alkali metal-ion under low-temperature conditions.