Jun 21 2022Reviewed by Alex Smith
A novel approach to building improved, safer lithium-metal batteries has been formulated by Stanford scientists in a new study.
A new study presents possible solutions to a problem known to cause degradation and failure in lithium-metal batteries. Image Credit: alengo/iStock.
Closely related to the rechargeable lithium-ion cells, extensively used in electric cars and handy electronics, lithium-metal batteries offer remarkable promise as next-generation energy storage devices. In contrast to lithium-ion devices, lithium-metal batteries can contain more energy, weigh significantly less, and charge up faster.
Until now, though, the commercial application of rechargeable lithium-metal batteries has been minimal. A core reason is the development of “dendrites” – thin, metallic, tree-like structures that form as lithium metal amasses on electrodes within the battery. These dendrites reduce battery performance and eventually cause failure which, in a few instances, has even started a fire.
The new research tackled this dendrite issue from a theoretical standpoint. As illustrated in the article, published in the Journal of The Electrochemical Society, Stanford scientists created a mathematical model that combines the chemistry and physics involved in dendrite development.
This model presented the insight that substituting new electrolytes – the medium via which lithium ions flow between the two electrodes within a battery – with specific properties could decelerate or even completely halt dendrite development.
“Our study’s aim is to help guide the design of lithium-metal batteries with longer life span,” said the study lead author Weiyu Li, a Ph.D. student in energy resources engineering co-advised by Professors Daniel Tartakovsky and Hamdi Tchelepi. “Our mathematical framework accounts for the key chemical and physical processes in lithium-metal batteries at the appropriate scale.”
This study provides some of the specific details about the conditions under which dendrites can form, as well as possible pathways for suppressing their growth.
Hamdi Tchelepi, Study Co-Author and Professor of Energy Resources Engineering, School of Earth, Energy, and Environmental Sciences, Stanford University
A Direction for Design
Experimentalists for a long time have strived to comprehend the factors resulting in dendrite formation, but the lab work is arduous, and results have been quite hard to deduce. Identifying this challenge, the scientists created a mathematical representation of the batteries’ inner electric fields and movement of lithium ions via the electrolyte material, together with other applicable mechanisms.
Upon acquiring the findings of the study, experimentalists can concentrate on physically reasonable material and architecture arrangements.
Our hope is that other researchers can use this guidance from our study to design devices that have the right properties and reduce the range of trial-and-error, experimental variations they have to do in the lab.
Hamdi Tchelepi, Study Co-Author and Professor of Energy Resources Engineering, School of Earth, Energy, and Environmental Sciences, Stanford University
In particular, the new methods for electrolyte design formulated by the study include finding materials that are anisotropic, meaning they display varied properties in diverse directions. Wood is a typical example of an anisotropic material, which is sturdier in the direction of the grain, visible as lines in the wood, as opposed to against the grain.
With regard to anisotropic electrolytes, these materials could tweak the intricate interplay between ion transport and interfacial chemistry, preventing accumulation that proceeds dendrite development. Certain liquid crystals and gels display these preferred features, according to the scientists.
Another method discovered by the study is based on battery separators – membranes that stop electrodes at opposite ends of the battery from making contact and short-circuiting. New types of separators could be engineered to possess pores that cause lithium ions to travel to and fro via the electrolyte in an anisotropic manner.
Building and Testing
The researchers are keen to see other scientists pursue the “leads” discovered in their study. Those subsequent steps will entail building real devices that depend on new trial electrolyte formulations and battery architectures, and then verifying which might be scalable, operational, and economical.
An enormous amount of research goes into materials design and experimental verification of complex battery systems, and in general, mathematical frameworks like that spearheaded by Weiyu have been largely missing in this effort.
Daniel Tartakovsky, Study Co-Author and Professor of Energy Resources Engineering, School of Earth, Energy, and Environmental Sciences, Stanford University
Based on these recent results, Tartakovsky and colleagues are involved in building an entirely virtual representation – called a “digital avatar” – of lithium-metal battery platforms, or DABS.
This study is a key building block of DABS, a comprehensive ‘digital avatar’ or replica of lithium-metal batteries that is being developed in our lab. With DABS, we will continue to advance the state of the art for these promising energy storage devices.
Daniel Tartakovsky, Study Co-Author and Professor of Energy Resources Engineering, School of Earth, Energy, and Environmental Sciences, Stanford University
Yiguang Ju, who is also the study’s co-author, is a professor of mechanical and aerospace engineering at Princeton University.
This study received funding from Hyundai Motor Group, the Air Force Office of Scientific Research, and by a gift from TotalEnergies.
Journal Reference:
Li, W., et al. (2022) Stability-Guided Strategies to Mitigate Dendritic Growth in Lithium-Metal Batteries. Journal of The Electrochemical Society. doi.org/10.1149/1945-7111/ac7978.
Source: https://stanford.edu