Published on April 25th, 2016 | by Tina Casey36
“Infinite” Energy Storage Finally Discovered, But There’s A Catch
April 25th, 2016 by Tina Casey
The Intertubes have been buzzing with news that a research team based at UC-Irvine has created a new type of energy storage device that can last for more than 100,000 charges. For all practical purposes, that counts as an infinite battery. Under real life conditions, such a battery would most likely outlive the device it powers, and it might even outlive the owner of the device as well.
The new battery is still in the early research stage, but if it pans out, it would have a significant impact on lifecycle and supply chain issues for the ballooning number of smart phones, electric vehicles, energy storage products, and countless other battery powered devices inhabiting the Earth.
The Energy Storage Catch.
The new energy storage device is described in a just-published study, which you can find at the American Chemical Society under the title, “100k Cycles and Beyond: Extraordinary Cycle Stability for MnO2 Nanowires Imparted by a Gel Electrolyte.”
The research team has been tackling an alluring, next-generation approach to lithium-ion energy storage that has been giving the research community quite a headache.
Previous research has demonstrated that you can use the same material to make an even more powerful battery. All you have to do is use it in the form of nanowires (nanowires are incredibly thin strings of material) instead of thin films.
The problem is battery lifespan. All-nanowire batteries require extraordinarily long wires. As the study describes, they don’t stand up under working conditions:
By design, the ultralong nanowires in these capacitors amplify the influence of degradation processes that culminate in breakage of the nanowire because for ultralong nanowires, breakage “disconnects” a larger fraction of the total energy storage capacity of the electrode.
Nevertheless, the team has been hammering away with different formulations of the nanowire structure to see where improvements could be made. In a previous study, they achieved some improvement with the material manganese oxide (MnO2), hitting a mark of 4,000 charging cycles while retaining capacity.
That’s where the catch comes in. The battery being worked on by the team is not quite ready for its Tesla moment. It is a capacitor, which is fancyspeak for a device that holds and releases a charge in an electrical circuit.
Capacitors have many uses, but the team is some degree of labwork away from developing the kind of rechargeable battery that can power an EV or store renewable energy.
On the other hand, you have to start somewhere, and the team did set a high bar. In the study, the researchers note that some researchers have reported up to 10,000 cycles for capacitors based on nanotubes of graphene and Mn3O4 (that’s a different oxidation state of manganese). They also note that capacitors based on a-Mn2O3 thin films have been reported as high as 200,000 cycles.
A Happy Energy Storage Accident…Or Not
In the new study, the team used the same MnO2 nanowires to bump their capacitor from the range of 2,000-8000 cycles all the way up to more than 100,000. The solution was simple: they replaced a liquid electrolyte (that’s the part of a battery that holds a charge) with a gel made of poly(methyl methacrylate), aka PMMA. The glass-like material is also known by the trade name Plexiglass.
Scientific discovery is full of happy accidents, and this could be one of those. According to the study’s author cited in UC-Irvine’s press release, research team leader Mya Le Thai was “playing around” with PMMA when she hit upon the solution.
On the other hand, we’re thinking that Thai directed her research a little more purposefully than the press materials describe. PMMA has earned the attention of clean tech researchers, for example in the solar energy field, and researchers have also fiddled around with thin films of PMMA in capacitors.
Accidentally or not, the new study charts a new path for improving energy storage technology, and that’s a good thing.
Next steps probably include figuring out a way to achieve the same results with cheaper materials. Aside from MnO2 nanowires, the new capacitor also consists of a central gold wire. That’s going to be a tough row to hoe, since the gold wire is the one that enables access to the energy storage capacity of the MnO2 shell, so stay tuned.
Photo (cropped): by Steve Zylius / UCI (UC-Irvine).