Replacing the liquid electrolyte used in lithium-ion batteries with a solid electrolyte is widely believed to significantly improve both energy density and safety. However, the transition to solid-state batteries still faces numerous unresolved challenges, and the path to large-scale commercialization remains unclear.
Against this backdrop, a breakthrough that has propelled the transition from lithium-ion batteries to solid-state batteries into a new phase is the University of Oxford’s spelucidation of the dendrite formation mechanism in lithium metal solid-state batteries (Li-SSBs) *¹
This report provides a concise overview of their findings.
Contents
University of Oxford Elucidates the Lithium Dendrite Formation Mechanism
With the global shift toward electric vehicles (EVs), the development of all-solid-state batteries has become a major focus for leading automotive and electronics manufacturers, as well as for academic and research institutions. Among the various candidates, lithium metal solid-state batteries (Li-SSBs), which employ lithium metal as the anode material, are considered one of the most promising next-generation battery technologies and are the subject of intensive research.
Lithium metal solid-state batteries offer enhanced safety due to their extremely low risk of combustion. In addition, their high energy density enables high power output, making them suitable for large-scale equipment and high-performance devices.
Despite these advantages, lithium dendrite formation during charging—and the resulting internal short circuits*²—has long posed a major challenge for these batteries. Without a clear understanding of the underlying mechanisms, effective mitigation strategies could not be developed.
On June 7, 2023, the University of Oxford reported that it had successfully elucidated the mechanism of dendrite formation in lithium metal solid-state batteries*³.
To achieve this, the research team employed state-of-the-art X-ray computed tomography at the UK´s national synchrotron radiation facility, Diamond Light Source (DLS)*⁴, enabling detailed imaging and analysis of lithium dendrites.
The analysis revealed that crack formation associated with dendrites proceeds through distinct mechanisms during the initial and growth stages. Importantly, it was confirmed that entirely different physical processes govern each stage*⁵.
X-ray Analysis Results and Future Potential of Lithium Metal Solid-State Batteries
When dendrites form, lithium metal filaments penetrate the ceramic electrolyte, generating cracks within the material.
According to the analysis, the initial stage of cracking begins with lithium accumulation in subsurface pores. Once these pores become fully saturated, continued charging leads to pressure buildup, which in turn initiates crack propagation*⁵.
In contrast, crack growth at later stages occurs through a different mechanism when lithium is only partially deposited. This process follows a “wedge-opening” principle, in which force is applied from behind—similar to a wedge—causing the crack to expand*⁵.
Oxford
Commenting on these findings, researcher Dominic Melvin, Ph.D., noted:
“While lithium pressure during discharge can be beneficial for maintaining good contact with the electrolyte, excessive pressure during charging can promote dendrite growth and lead to short circuits.”
According to Dr. Melvin, realizing practical lithium metal solid-state batteries represents one of the most critical challenges in modern battery technology. He emphasized that continued research in this area has the potential to become a game-changer for the industry.
This lithium dendrite imaging study was conducted as part of The Faraday Institution’s project known as “SOLBAT”*⁶. The Faraday Institution forecasts that by 2040, all-solid-state batteries will account for approximately 50% of consumer electronics applications, 30% of transportation uses, and up to 10% of aircraft power systems.
The findings reported by the University of Oxford mark a significant step toward the practical deployment of all-solid-state batteries. Amid intensifying global competition in battery development, this research has made a notable impact and may ultimately prove to be a true game-changer.
References
※2:全固体リチウムイオン電池用固体電解質におけるリチウム析出現象のメカニズム解明/東北大
学 – KAKEN
※3:“Game-Changing” Batteries for Electric Vehicles and Aviation unlocked by Oxford Study -Editorialge
