Multiscale modification of graphdiyne-based electrodes and diffusion kinetics analysis of lithium ions

Abstract

The diffusion of lithium ions is highly related to the chemical structure, packing mode, and pore size distribution of the electrode materials. In this paper, a multiscale modification strategy is performed to investigate the correlation between the chemical structure and diffusion kinetics of lithium ions in graphdiyne (GDY) based electrodes. Various electrochemical tests show consistent results that hydrogen-substituted GDY has the fastest lithium-ion diffusion rate, and the doping of Cl and F atoms with large atomic radii leads to slower lithium-ion diffusion in the system. The functional groups (H, Cl, F) introduced in the GDY-based electrodes not only regulate the pore size of the materials but also modulate the binding energy with lithium ions. chlorine-substituted GDY shows a higher diffusion coefficient than that of fluorine-substituted GDY for proper affinity to lithium. In addition, the specific surface area and the pore size distribution also collectively contribute to the differences in lithium-ion diffusion. Finally, the lithium storage mechanism of substituted GDY electrodes is explored. Our strategy sheds some light on the design and fabrication of anode materials for lithium-ion batteries.