Electrochemical Performance of Nitrogen‐Doped Graphene/Silicene Composite as a Pseudocapacitive Anode for Lithium‐ion Battery

Silicene, as a two-dimensional (2D) nanostructure of silicon with many active sites for charge distribution, suitable space to control the volumetric strain, and an adjustable bandgap has attracted more attention as an anode for lithium-ion batteries. Nitrogen, with a small radius and high electronegativity, is pretty good to form an n-type configuration of silicene. Herein, single-crystal silicene with adjusting nitrogen atoms at pyrrolic and graphitic sites in the graphene layer is identified by XRD, XPS, and Raman analyses for nitrogen-doped graphene/silicene (NG/SNS) composite. Electrochemical performance of silicene exhibits the first intercalation/deintercalation capacity of 1030/768 mAh/g with 74 % Columbic efficiency (CE) at a current density of 10 mA/g, whereas NG3-SNS with 0.3 g NG precursor shows the first intercalation/deintercalation capacity of 795/600 mAh/g with 75.4 % CE. Interestingly, NG3-SNS indicates a stable specific capacity of similar to 600 mAh/g at 200th cycle with 100 % CE and a second volumetric capacity of 3352 mAh/cm(3) with 80 % retention after 200 cycles at a current density of 100 mA/g. Subsequently, the high electronegativity of nitrogen results in lone pair in both hybridized configurations of graphitic-NG and pyrrolic-NG; which may cause effortless adsorption/desorption of Li+-ion at the nitrogen sites, as well as, pyrrolic sites help to develop diffusion of Li+-ion and graphitic sites help to accelerate the kinetics and surface-controlled contributions.