Yes, it’s true that lithium-ion batteries currently own the crown in the battery world; they’re everywhere, from TV remotes to smartphones and everything in between. And for good reason, too: these kinds of batteries are pretty good at what they set out to do. However, much like the rest of innovations we now take for granted in the modern age, lithium-ion batteries too have a couple of drawbacks.
You see, when batteries discharge, electrons flow from the battery to the circuit inside the device in question. However, as you might expect, the electrochemical reaction going on within the battery must remain balanced; as a result, positive charges—in the form of charge carriers like ions—must flow in the opposite direction to compensate. This flow of ions, which can be reversed as is the case with rechargeable batteries, often causes the build-up of structures in the anode called dendrites, which are made of the charge-carrying ions in question.
The formation of these dendrites can hamper, and sometimes even outright disable, the function of these batteries, as they obstruct the flow of charge carriers to and from the anode that they’re now covering. This leads to critical battery failure, which can come in the form of overheating or short-circuiting.
Thus, scientists are on the case to find solutions for some of the problems concerning lithium-ion batteries; one such case is the search for alternatives to the battery technology—and there are few proposed solutions out there, like those in proposed chlorine-based batteries.
A particular solution brought up by scientists from the University of Texas at Austin (UTAustin) aims to tackle two problems all at once, though. These intrepid minds plan to eschew the use of lithium altogether, which is why they’re targeting sodium (Na) instead.
Sodium has long been touted as a potential alternative to lithium, partly due to it being cheaper and more environmentally-friendly and compared to its lithium counterpart. However, much like lithium, sodium too has its own share of dendrite formation problems. These UTAustin scientists have a proposed solution to combat dendrite formation: they instead mixed the sodium in with other components in a new anode material they call sodium antimony telluride (Na-Sb-Te) intermetallic (SATI). Their novel solution to negate dendrite formation was published in the journal Advanced Materials.
“We’re essentially solving two problems at once,” said co-author and UTAustin professor David Mitlin in the institution’s news release. “Typically, the faster you charge, the more of these dendrites you grow. So if you suppress dendrite growth, you can charge and discharge faster, because all of a sudden it’s safe.”
The SATI is made by rolling bare sheets of sodium metal onto antimony telluride powder. From here, the composite is folded in over itself, after which the process repeats several times. This creates a layered structure for the anode, which the authors likened to “making a […] layered pastry.”
The end result is a uniform distribution of sodium atoms across the material, which spaces them out evenly—in turn making dendrite formation less likely. This addresses the issue in a certain way, as dendrites tend to form at imperfections on the anode surface. And since the formation of dendrites tends to cause the formation of even more dendrites, it’s important to nip the problem in the bud, which is precisely what the UTAustin scientists set out to do.
“This material is also exciting because the sodium metal anode theoretically has the highest energy density of any sodium anode,” said co-author and fellow UTAustin professor Graeme Henkelman, describing how, in theory, sodium can carry the highest amount of energy per unit mass compared to other sodium-based anode materials.
Additionally, the prevention of dendrite formation enables faster charging and increased stability—and for good measure, as the SATI also seems to showcase a higher energy capacity compared to other sodium-ion batteries.
The UTAustin team has since patented their potential battery technology, so we may find it in the newest batteries sooner rather than later.
(For similar reads, check out how electrochemical pulses can help the monitoring of future solid-state batteries.)
References
- Lavars, N. (2021, December 7). Electrode takes after layered pastry to give eco-friendly battery a boost. New Atlas. https://newatlas.com/energy/electrode-layered-pastry-eco-friendly-sodium-battery/
- Sodium-based Material Yields Stable Alternative to Lithium-ion Batteries. (2021, December 6). Walker Department of Mechanical Engineering; The University of Texas at Austin. https://www.me.utexas.edu/news/1557-sodium-based-material-yields-stable-alternative-to-lithium-ion-batteries
- Wang, Y., Dong, H., Katyal, N., Hao, H., Liu, P., Celio, H., Henkelman, G., Watt, J., & Mitlin, D. (2021). A sodium–antimony–telluride intermetallic allows sodium‐metal cycling at 100% depth of discharge and as an anode‐free metal battery. Advanced Materials, 2106005. https://doi.org/10.1002/adma.202106005
