Si2BN is also used as an anode for lithium ion or sodium ion batteries

Lithium ion batteries play an increasingly important role in energy storage. Companies such as Tesla see it as an energy storage solution for electric cars and a solution to intermittent problems related to renewable energy. Their massive energy density and capacity for multiple charging cycles have made them almost ubiquitous on mobile devices - but they've run into problems.

Sodium ion batteries have become recent competitors; Sodium is more abundant than lithium, and these batteries have better safety records and fewer fires. Two-dimensional materials with the maximum surface area to volume ratio, high conductivity and high ionic diffusivity may replace bulky materials, such as graphite, because these batteries have higher energy density and are more versatile.

As the field of synthesizing and characterizing 2D materials becomes more advanced, these seemingly magical substances exhibit fascinating and often very useful properties. Theorists have been keenly exploring the computational potential of these materials because of the widespread use of new methods of laminating atoms onto substrates, such as stripping to synthesize graphene first, and atomic layer deposition or molecular beam epitaxy. Such calculations were made in 2015 with the potential to synthesise Si2BN's graphene-like layer with two silicon atoms bound to boron and nitrogen atoms.

Other graphene analogs such as germanium show buckling in lattice structures, but Si2BN has flattened hexagonal structures that allow the formation of nanotubes. The material is expected to be stable under a variety of physical conditions - possibly up to 800K or higher temperatures.

This single-layer Si2BN has been described with a number of theoretical characteristics that are of considerable interest to the renewable energy industry. At first, it was thought that it might be a useful means of hydrogen storage. Many renewable energy advocates want to store intermittent energy from wind turbines and solar panels as hydrogen, which can be produced by electrolysis during peak supply periods.

One factor preventing the "hydrogen economy" from taking off is the difficulty of storing hydrogen, which is not a particularly energy-dense and gas-like explosive; So research teams, including the U.S. department of energy, are trying to find materials that can bond with hydrogen atoms. The presence of silicon on the surface of the layer raised hopes that it was reactive enough to store large amounts of hydrogen - but it also caused another positive effect. Si2BN is an excellent anode for lithium ion batteries.

A 2017 paper on nanoenergy described this property. The paper's title - "2d Si2BN: a curious situation with a high-capacity battery cathode material" - says something about the unusual properties of this material. It has the theoretical ability to absorb and store lithium ions, which is five times higher than the existing anode materials currently used in batteries. 2D materials already synthesized also generally show good adsorption properties, but 2DSi2BN could well be combined with other materials such as silicene, borophene and 2D black phosphorus, as well as other materials such as graphite, titanium dioxide and molybdenum diselenide.

The results show that the key lies in the Si-Si bond and the unique response of the structure to the adsorbed ions. As lithium/sodium ions enter the material, they cause the structure to bend. This will give the overall structure a higher capacity than other 2D materials. This buckling, which is seen in other 2D materials such as germanium, manifests as a phase transition when more than one ion is adsorbed on the surface. According to these calculations, the phase transition should be completely reversible and facilitate the diffusion of ions from the anode.

Si2BN is also expected to have even more electronic properties, making 2-d materials a source of considerable excitement in the field of materials science. It is powerful, flexible, has a tunable band gap, and has high conductivity and high conductivity. The fact that Si2BN has high electron mobility is critical to its usefulness as an anode. This is combined with the fact that ions are highly diffused to allow batteries to charge and discharge quickly. Creating fast rechargeable batteries that can reliably store large amounts of energy is important for grid storage and backup as well as applications in electric vehicles.

Si2BN has never been synthesized in large quantities, although a number of different teams are currently working to create this 2D material. The field is advancing rapidly: a few years ago, boron fluorene was considered a promising anode material. Almost immediately following successful synthesis (2015), the report for the first time predicts that Si2BN may exceed the capacity of its anode. Theoretical predictions of these electronic properties enable material scientists to explore the physical possible parameter space. The next step will be to build a prototype battery to test the field's anode performance, and then refine the battery to bring it closer to the theoretical maximum of ion storage. As our demand for larger capacity and more flexible energy storage systems increases, this breakthrough could be critical for continued technological improvement.

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