Lithium Metal Batteries and the Push for More Sustainable Electronics

Lithium metal batteries, a key component in many appliances and electronics, contribute to global sustainability. Using batteries to power electronic devices can help reduce carbon footprint and reliance on fossil fuels.

Currently, there is a push to make batteries last longer and operate more effectively. This is motivated by the call for more affordable modes of transportation and effective electronic devices. Because of this more scientists are investigating lithium metal batteries using analytical techniques to analyze different electrical components.

Many technological devices like electric vehicles and smart phones run on batteries with graphite anodes. These anodes are essential components in lithium-ion batteries and are the primary materials that dictate charge capacity and high conductivity performance (1). Lithium-ion batteries have different chemistries compared to lithium metal batteries.

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Chengcheng Fang, an assistant professor of Chemical Engineering and Materials Science at Michigan State University, described the difference between the two in this way in MIT Technology Review.

“In a lithium-ion battery, graphite is used as the anode, one of the two electrodes in a battery, to host lithium ions during battery charge and discharge,” Fang said to MIT Technology Review (2). “In a lithium metal battery, we use lithium metal as the anode, which offers more than 10 times higher capacity than that of graphite.”

Recent studies have examined alternatives to graphite anodes and instead using lithium metal anodes that could further improve battery charging capacity and performance. Li and his team examined the thermodynamics of a solid-state battery and determined that it could be fundamentally different from liquid electrolyte lithium-ion batteries to achieve a better performance (3,4). In another example, Gu and others used depth-sensitive plasmon-enhanced Raman spectroscopy (DS-PERS) to examine the processes of solid-electrolyte interphase (SEI) in lithium metal batteries (5). The SEI plays an important role in the operation of lithium-ion batteries, and SEI performance is crucial to the longevity and performance of lithium metal batteries (5).

What is SEI and its Critical Functions?

The SEI is a layer formed on the electrode surface (6). It allows for electrochemical reactions to take place in batteries and helps keep the battery stable to ensure optimal performance (6). Because the SEI is important to battery performance, studying it is essential to learning more about its operation and how it can be adjusted to improve the performance of anode-free lithium metal batteries (5).

Columbia University Professor Lauren Marbella and her team are exploring this issue. By using nuclear magnetic resonance (NMR) imaging and spectroscopy to study changes in material properties in real time, she and her team have been able to learn more about the chemical mechanisms behind degradation in lithium and other battery systems (7,8).

“The SEI is very thin, only a few nanometers thick, so advanced analytical techniques are needed to detect it and even then, there is not a lot of material there, especially compared to its surroundings (like the electrode and the electrolyte) that are present at several orders of magnitude higher that can overwhelm its signal,” Marbella said (7). “It is air sensitive, so if you try to analyze it outside of the battery, you might damage it.”

Improving Battery Performance

The “Electric revolution,” as it’s been described is overwhelming the electrical grid (2) and is resulting in the mass exploration and production of new battery technologies. Much research has gone into exploring lithium-ion batteries already, but production cannot keep up with the demand for these batteries. Plus, lithium-ion batteries are still too heavy, expensive, and require a long charging time (2).

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The hope is that the shift from using lithium-ion batteries to lithium metal batteries will help increase battery performance and charging capacity, ultimately reducing the strain on the electric grid.

Scientists from Stanford University have been looking at ways to use different materials to improve the lithium metal battery’s cycle life (9). In a recent study published in Nature, they described a straightforward approach to boost battery performance, which involves draining the battery and letting it rest for hours at a time.

“We were looking for the easiest, cheapest, and fastest way to improve lithium metal cycling life,” said study co-lead author Wenbo Zhang, a Stanford PhD student in materials science and engineering (9). “We discovered that by resting the battery in the discharged state, lost capacity can be recovered and cycle life increased. These improvements can be realized just by reprogramming the battery management software, with no additional cost or changes needed for equipment, materials, or production flow.”

“A car equipped with a lithium metal battery would have twice the range of a lithium-ion vehicle of equal size – 600 miles per charge versus 300 miles, for example,” said co-lead author Philaphon Sayavong, a PhD student in chemistry at Stanford University (9). “In EVs, the goal is to keep the battery as lightweight as possible while extending the vehicle range.”

Outlook

Using lithium metal anodes instead of graphite could be the way forward in the battery industry (5,10). Besides better performance, lithium metal batteries are believed to have economic benefits to consumers. As the push for more electric vehicles becomes more pervasive, car manufacturers will be forced to mass produce more electric vehicles to comply with state and federal regulations. Consumers, however, could be hurt by these mandates unless electric vehicles become more market competitive.

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The problem, as it currently stands, is that lithium metal batteries need to be researched more before they can be commercialized. Lithium metal is a very reactive element on the periodic table, meaning that it easily develops a passivation layer that could impact anode structure and reduce its effectiveness (10). Therefore, researchers need to learn more about the chemistry of the passivation layer and how it impacts lithium ions during battery charging.

“If we had this information, we could start to draw connections to specific SEI structures and properties that lead to high-performance batteries,” Marbella said (10).

The goal, Marbella said, is to help propel this research forward with the end goal of the commercialization of lithium metal batteries.

“We believe that, armed with all the data we’ve pulled together, we can help accelerate the design of lithium metal batteries and help make them safe for consumers, which folks have been trying to do for more than four decades,” Marbella said to Columbia Engineering (10).

References

(1) Aqua Metals, What is Graphite, and Why is it so Important in Batteries? Aqua Metals. Available at: https://www.aquametals.com/recyclopedia/why-is-graphite-so-important-to-lib/ (accessed 2024-07-12).

(2) MSU Today, Improving ‘Holy Grail’ Lithium Metal Batteries: Q&A with Engineer Chengcheng Fang. MSU.edu. Available at: https://msutoday.msu.edu/news/2022/q-a-with-chengcheng-fang-bot#:~:text=Q:%20What%20is%20the%20difference,%E2%80%9Choly%20grail%E2%80%9D%20of%20batteries?(accessed 2024-07-15).

(3) Sullivan, K. D. Lithium-Metal Batteries vs. Lithium-Ion. Labroots. Available at: https://www.labroots.com/trending/chemistry-and-physics/20448/lithium-metal-batteries-vs-lithium-ion (accessed 2024-07-14).

(4) Ye, L.; Li, X. A Dynamic Stability Design Strategy for Lithium Metal Solid State Batteries. Nature 2021, 593, 218–222. DOI: 10.1038/s41586-021-03486-3

(5) Gu, Y.; You, E.-M.; Lin, J.-D.; et al. Resolving Nanostructure and Chemistry of Solid-Electrolyte Interphase on Lithium Anodes by Depth-Sensitive Plasmon-enhanced Raman Spectroscopy. Nat. Commun. 2023, 14, 3536. DOI: 10.1038/s41467-023-39192-z

(6) He, Y.; Jiang, L.; Chen, T.; et al. Progressive Growth of the Solid–Electrolyte Interphase Towards the Si Anode Interior Causes Capacity Fading. Nat. Nanotechnol. 2021, 16, 1113–1120. DOI: 10.1038/s41565-021-00947-8

(7) Wetzel, W. Lithium Metal Batteries and the Critical Function of Solid Electrolyte Interphases: An Interview with Lauren Marbella of Columbia University. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/lithium-metal-batteries-and-the-critical-function-of-solid-electrolyte-interphases-an-interview-with-lauren-marbella-of-columbia-university (accessed 2024-07-12).

(8) Columbia University Engineering, Lauren Marbella. Columbia.edu. Available at: https://www.cheme.columbia.edu/faculty/lauren-marbella (accessed 2024-07-12).

(9) Stanford University, Sitting Idle Boosts the Performance of Lithium Metal Batteries for Next-Generation EVs. Stanford.edu. Available at: https://news.stanford.edu/stories/2024/02/resting-boosts-performance-lithium-metal-batteries (accessed 2024-07-12).

(10) Evarts, H. Designing Safer, Higher-Performance Lithium Batteries. Columbia.edu. Available at: https://www.engineering.columbia.edu/news/using-magnetic-resonance-spectroscopy-design-safer-higher-performance-lithium-batteries (accessed 2024-07-12).