Oxford Research Sets Stage for Potential Battery Breakthroughs in Electric Vehicles and Aviation

A team of researchers has employed sophisticated imaging methodologies to probe into the reasons behind the failure of lithium metal solid-state batteries (Li-SSBs), reveals a study published in Nature. Li-SSBs stand apart from traditional batteries as they replace the potentially dangerous liquid electrolyte with a solid one and utilize lithium metal as the anode. This replacement provides enhanced safety and larger energy storage capacity, potentially triggering a transformation in the electric vehicle (EV) and aviation industries.

Researchers from the University of Oxford have identified the reasons why lithium metal solid-state batteries (Li-SSBs) fail, laying the groundwork for potential improvements in EV batteries. They identified the formation and growth of ‘dendrites’ as the root cause of battery short-circuits, an insight that could help mitigate obstacles in solid-state battery development.

The study uncovered the mechanisms behind the failure of lithium metal solid-state batteries. High-resolution imaging was used by researchers to visualize batteries during charging with an unprecedented level of detail. This newfound understanding could help resolve technical challenges with solid-state batteries, setting the stage for a revolutionary technology in the realm of electric vehicles and aviation.

Thanks to a new study led by researchers from the University of Oxford and published in Nature on June 7, significant advancements in electric vehicle (EV) batteries may be on the horizon. Advanced imaging techniques were used to uncover the failure mechanisms of lithium metal solid-state batteries (Li-SSBs). Overcoming these issues could lead to a significant leap in the performance, safety, and range of EV batteries, and promote the growth of electric aviation.

Dominic Melvin, a PhD student in the University of Oxford’s Department of Materials and one of the study’s co-lead authors, stated: “Making progress with solid-state batteries using lithium metal anodes represents a crucial challenge in advancing battery technologies. While we anticipate continued enhancements in today’s lithium-ion batteries, research into solid-state batteries has the potential to deliver significant rewards and herald a transformative technology.”

Li-SSBs differentiate themselves from other batteries by replacing the flammable liquid electrolyte with a solid one and using lithium metal as the anode. The solid electrolyte bolsters safety, and the use of lithium metal allows for higher energy storage. A significant issue with Li-SSBs, however, is their tendency to short-circuit during charging due to the growth of “dendrites”: lithium metal filaments that penetrate the ceramic electrolyte. Under the umbrella of the Faraday Institution’s SOLBAT project, a team of researchers from the University of Oxford’s Departments of Materials, Chemistry, and Engineering Science, embarked on an intensive investigation to understand more about this short-circuiting process.

In this most recent study, the team employed an advanced imaging technique known as X-ray computed tomography at Diamond Light Source to visualize dendrite failure during the charging process with unparalleled detail. They found that the initiation and growth of dendrite cracks are distinct processes, each driven by separate underlying mechanisms. The cracks begin to form when lithium accumulates in sub-surface pores. When these pores fill up, continued charging of the battery increases pressure, leading to cracking. In contrast, crack propagation occurs with only partial filling of the crack by lithium, through a mechanism which forces the crack to open from behind.

This fresh insight provides a roadmap to overcoming the technological challenges of Li-SSBs. Dominic Melvin said: “Our results demonstrate that while some pressure at the lithium anode can be beneficial in preventing gaps from forming at the interface with the solid electrolyte during discharge, too much pressure can be harmful, making dendrite propagation and short-circuiting more likely during charging.”

Sir Peter Bruce, Wolfson Chair, Professor of Materials at the University of Oxford, Chief Scientist of the Faraday Institution, and the study’s corresponding author, said: “It has been a complex challenge to understand how a soft metal like lithium can penetrate a highly dense hard ceramic electrolyte, with many valuable contributions from excellent scientists globally. We hope that our additional insights will contribute to the progress of solid-state battery research towards a practical device.”

A recent report by the Faraday Institution suggests that by 2040, SSBs could meet 50% of the global demand for batteries in consumer electronics, 30% in transportation, and over 10% in aircraft.

Professor Pam Thomas, CEO of the Faraday Institution, said: “The SOLBAT researchers continue to develop a mechanistic understanding of solid-state battery failure – a hurdle that needs to be overcome before high-power batteries with commercially viable performance can be realized for automotive applications. The project is contributing to strategies that manufacturers could adopt to prevent cell failure with this technology. This application-inspired research exemplifies the type of scientific advancements the Faraday Institution was designed to foster.”

Reference: “Dendrite initiation and propagation in lithium metal solid-state batteries” by Ziyang Ning, Guanchen Li, Dominic L. R. Melvin, Yang Chen, Junfu Bu, Dominic Spencer-Jolly, Junliang Liu, Bingkun Hu, Xiangwen Gao, Johann Perera, Chen Gong, Shengda D. Pu, Shengming Zhang, Boyang Liu, Gareth O. Hartley, Andrew J. Bodey, Richard I. Todd, Patrick S. Grant, David E. J. Armstrong, T. James Marrow, Charles W. Monroe and Peter G. Bruce, 7 June 2023, Nature. DOI: 10.1038/s41586-023-05970-4

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More about Lithium Solid-State Batteries

• Faraday Institution
• Nature Journal
• University of Oxford’s Department of Materials
• SOLBAT project
• Diamond Light Source