An international team of scientists from NUST MISIS, Russian Academy of Science and the Helmholtz-Zentrum Dresden-Rossendorf has found that instead of lithium (Li), sodium (Na) “stacked” in a special way can be used for battery production. Sodium batteries would be significantly cheaper and equivalently or even more capacious than existing lithium batteries. The results of the study are published in the journal Nano Energy.
The most promising replacement for lithium is sodium (Na), since a two-layer arrangement of sodium atoms in bigraphen sandwich demonstrates anode capacity comparable to the capacity of a conventional graphite anode in Li-ion batteries—about 335 mA*h/g against 372 mA*h/g for lithium. However, sodium is much more common than lithium, and therefore cheaper and more easily obtained.
A special way of stacking atoms is actually placing them one above the other. This structure is created by transferring atoms from a piece of metal to the space between two sheets of graphene under high voltage, which simulates the process of charging a battery. In the end, it looks like a sandwich consisting of a layer of carbon, two layers of alkali metal, and another layer of carbon.
Zakhar Popov, senior researcher at NUST MISIS Laboratory of Inorganic Nanomaterials and RAS, says, “Our simulation shows that lithium atoms bind much more strongly to graphene, but increasing the number of layers of lithium leads to less stability. The opposite trend is observed in the case of sodium—as the number of layers of sodium increases, the stability of such structures increases, so we hope that such materials will be obtained in the experiment.”
The next step of the research team is to create an experimental sample and study it in the laboratory. This will be handled in Max Planck Institute for Solid State Research, Stuttgart, Germany. If successful, it could lead to a new generation of Na batteries that will be significantly cheaper and equivalently or even more capacious than Li-ion batteries.