Ultrahigh Lithium Storage Capacity of Al2C Monolayer in a Restricted Multilayered Growth Mechanism

Biphenylite as Anode Materials for Alkali Metal Ion Batteries with Self-Enhanced Storage Mechanism

In this work, we theoretically investigate the feasibility of biphenylite, the van der Waals layered bulk structure from experimental biphenylene network monolayers, as an anode material for alkali metal ions. The results indicate that the theoretical properties of Li, Na, and K in biphenylite are generally beyond those in graphite. Li-biphenylite exhibits a high specific capacity of 744 mAh·g-1, with a corresponding voltage range of 0.90-0.36 V, low diffusion barrier (<0.30 eV), and small volume change (∼9.9%), far exceeding those of Li-graphite. Moreover, a novel self-enhanced storage mechanism is observed and unveiled, in which the heavy intercalation of Li atoms (i.e., electron doping) induces puckered distortion of the nonhoneycomb carbon frameworks to enhance the intercalation ability and capacity of Li ion via a chemical activation of carbon frameworks. Possessing excellent anode performance beyond graphite, biphenylite is a promising "all-around" anode material candidate for alkali metal ion batteries, especially for lithium ion batteries.

α-graphyne as a promising anode material for Na-ion batteries: a first-principles study

Lithium-ion batteries (LIBs) have emerged as a technological game-changer. Due to the rising price of lithium and the environmental concerns LIBs pose, their use is no longer viable. Sodium (Na) may be the best contender among the alternatives for replacing lithium. Conventional graphite has a limited capacity for Na storage. Hence,α-graphyne, an allotrope of carbon, was studied here as a potential anode material for Na-ion batteries (NIBs), employing density functional theory. In-plane Na atom adsorption results in a semi-metallic to metallic transition ofα-graphyne. Electronic transport calculations show an increase in current after Na adsorption in graphyne. The successive adsorption of Na atoms on the surface of graphyne leads to a theoretical capacity of 1395.89 mA h g^-1, which is much greater than graphite. The average open circuit voltage is 0.81 V, which is an ideal operating voltage for NIBs. Intra- and inter-hexagon Na diffusions have very low energy barriers of 0.18 eV and 0.96 eV, respectively, which ensure smooth operation during charge/discharge cycles. According to this study, theα-graphyne monolayer thus has the potential to be employed as an anode in NIBs.