Aluminene as a Low-Cost Anode Material for Li- and Na-Ion Batteries

Synthesis of Xenes: physical and chemical methods

Since the debut of silicene in the experimental stage more than a decade ago, the family of two-dimensional elementary layers beyond graphene, called Xenes or transgraphenes, has rapidly expanded to include elements from groups II to VI of the periodic table. This expansion has opened pathways for the engineering of elementary monolayers that are inherently different from their bulk counterparts in terms of fundamental physical properties. Common guidelines for synthesizing Xenes can be categorized into well-defined methodological approaches. On the one hand, bottom-up methods, such as physical epitaxial methods, enable the growth of monolayers, multilayers, and heterostructured Xenes. On the other hand, top-down chemical methods, including topotactic deintercalation and liquid-phase exfoliation, are gaining prominence due to the possibility of massive production. This review provides an extensive view of the currently available synthesis routes for Xenes, highlighting the full range of Xenes reported to date, along with the most relevant identification techniques.

Investigation of N 3 C 5 and B 3 C 5 bilayers as anode materials for Li-ion batteries by first-principles calculations

The best choice today for a realistic method of increasing the energy density of a metal-ion battery is to find novel, effective electrode materials. In this paper, we present a theoretical investigation of the properties of hitherto unreported two-dimensional B3 C5 and N3 C5 bilayer systems as potential anode materials for lithium-ion batteries. The simulation results show that N3 C5 bilayer is not suitable for anode material due to its thermal instability. On the other hand B3 C5 is stable, has good electrical conductivity, and is intrinsically metallic before and after lithium intercalation. The low diffusion barrier (0.27 eV) of Li atoms shows a good charge and discharge rate for B3 C5 bilayer. Moreover, the high theoretical specific capacity (579.57 mAh/g) connected with moderate volume expansion effect during charge/discharge processes indicates that B3 C5 is a promising anode material for Li-ion batteries.

Dirac t-Boron Nitride Monolayer as an Appealing Binder-Free Anode for Alkali Metal Ion Batteries

The development of universal anode materials with superlative electrochemical performance poses a great challenge for rechargeable alkali metal (AM) ion battery technologies. In the present work, the viability of the gapless Dirac t-BN (tetragonal boron nitride) monolayer as a lightweight binder-free anode has been systematically evaluated via comprehensive first-principles calculations. Aside from the desirable electronic conductivity, the t-BN monolayer exhibits an excellent ionic conductivity as well due to its moderate affinity for Li, Na, and K atoms with favorable in-plane barriers of 0.36, 0.18, and 0.19 eV, respectively. Meanwhile, the presence of B4N4 octagons allows the AM atoms to penetrate through the t-BN monolayer. Excitingly, the host material delivers an ultrahigh specific capacity up to 1080 mA h g-1 for Li, 5400 mA h g-1 for Na, and 2160 mA h g-1 for K in the wake of low mean open-circuit voltages of 0.033, 0.203, and 0.300 V at the half-cell level. According to the standard hydrogen electrode methodology, the energy densities are forecasted to be as large as 3240, 13500, and 5680 mW h g-1 for Li, Na, and K ion batteries, respectively, with robust thermal stability up to at least 400 K. The safety and cycling durability of the t-BN monolayer are jointly corroborated via the moderate mechanical strengths and ab initio molecular dynamics simulations at the maximum intercalated states, as well as via the small lattice changes and its ultrahigh tolerable ultimate tensile strain. These findings unambiguously promise that the t-BN monolayer can serve as an appealing candidate for anode applications in AM ion batteries.