Tesla could reap benefits of “truly exciting” glassy metal battery research

A “rare” glassy lithium metal observed by battery researchers, including Shirley Meng, the research partner for the Maxwell Technologies business acquired by Tesla in 2019, could lead to faster charging, higher capacity EV batteries.

“This is truly exciting!!! Glassy lithium might be the answer to the quest for fast charging lithium metal batteries,” said Meng in the tweet on Tuesday (Australian time).

Tesla CEO and co-founder Elon Musk has previously flagged Maxwell’s dry cell technologies as key to its planned electric Cybertruck.

It is not outside the realms of possibility that if the new research leads to commercially viable and significant battery improvements it will also be utilised by Tesla.

According to a release published by INL, the researchers found that by slowly charging lithium atoms at a very low rate produced a new “glassy” lithium material that has never been observed before and which can improve charging behaviour.

As The Driven has noted previously, lithium metal offers great potential for electric car batteries in its ability to store more energy and because it is lighter than graphite which is traditionally used for anodes.

However, it has inherent stability issues because the lithium atoms deposit in varying crystalline form onto an anode when a cell is being made.

Because “cracks” appear in polycrystalline batteries every time they are charged and discharged, this means batteries using lithium metal are currently not considered rechargeable.

The INL and UCSD researchers were seeking to better understand the “nucleation” process (when lithium atoms first come together) in the belief that improving regularity of the first early atom deposits could greatly improve cell performance.

“That initial nucleation may affect your battery performance, safety and reliability,” said Gorakh Pawar, an INL staff scientist and one of the paper’s two lead authors in a statement.

“It is critical to comprehend the underlying mechanism of lithium deposition…especially in the very early stage of nucleation,” they wrote.

The researchers were surprised to find that in certain conditions, instead of the usual crystalline form created during nucleation, that an amorphous, or glassy, form was taken.

“Compared to crystalline lithium, glassy lithium outperforms in electrochemical reversibility and is a desired structure for high-energy rechargeable batteries,” the authors wrote.

According to Meng, the discovery was made by using a powerful electron microscope to see the creation of the lithium metal “embryos,” after which computer simulations helped explain what they saw.

“The power of cryogenic imaging to discover new phenomena in materials science is showcased in this work,” said Shirley Meng, who led UC San Diego’s pioneering cryo-microscopy work.

Meng said that because imaging and spectroscopic data observed are often complicated, “It is true teamwork that enabled us to interpret the experimental data with confidence because the computational modeling helped decipher the complexity.”

EVen more exciting is that the researchers believe the amorphous nucleation structure could be retained throughout the anode structure growth.

“We can make amorphous metal in very mild conditions at a very slow charging rate,” said Boryann Liaw, an INL directorate fellow and INL lead on the work. “It’s quite surprising.”

Next steps are for the research to be applied to high-capacity batteries, which the researchers hope could be help meet the goals of the  Battery500 consortium, a US department of energy initiative that aims to develop commercially viable electric vehicle batteries with a cell level specific energy of 500Wh/kg.

Citation:
Glassy Li metal anode for high-performance rechargeable Li batteries
Wang, X., Pawar, G., Li, Y. et al. Glassy Li metal anode for high-performance rechargeable Li batteries.
Nat. Mater. (2020).
https://doi.org/10.1038/s41563-020-0729-1