Researchers at the University of Houston have identified a previously underestimated mechanical property of lithium dendrites, offering new insight into a persistent failure mechanism in lithium-based batteries, including solid-state systems.
The study, published in Science, shows that lithium dendrites are significantly stronger and more brittle than widely assumed. Rather than behaving as soft, easily deformable structures, the team found that dendrites can act as rigid, needle-like formations capable of penetrating solid electrolytes and separators, leading to internal short circuits.
The study was conducted by Yan Yao, distinguished professor of electrical and computer engineering at University of Houston, with colleagues from Rice University, Georgia Institute of Technology and Institute of High-Performance Computing in Singapore
Using operando scanning electron microscopy, the researchers observed dendrite formation and fracture in real time within working cells (see video). The analysis revealed that dendrites contain a single-crystal lithium core, reinforced by a surface layer that provides additional mechanical strength. This structure allows them to maintain integrity as they grow, increasing their ability to breach protective barriers.
Dendrite formation is typically associated with demanding operating conditions such as high charging rates and low temperatures – scenarios that are increasingly relevant as battery developers push for faster charging and higher energy density. While solid-state batteries have often been promoted as inherently safer due to their use of solid electrolytes, the findings suggest that mechanical resistance alone may not be sufficient to prevent dendrite-induced failure.
Lithium dentrites not soft and ductile
Yao said: “For decades, the scientific community assumed that solid-state electrolytes could easily block dendrites because lithium was thought to be a soft, ductile metal. We have proven they are actually brittle and snap like glass.”
“By filming this happening inside a working solid-state battery for the first time – using a specialised air-free chamber we invented here at UH – we’ve shown that the strategies used to design next-generation batteries have to change,” said Yao, who also serves as a Principal Investigator with the Texas Center for Superconductivity at UH.
The work has implications for the design of next-generation batteries, particularly those based on lithium metal anodes. The researchers suggest that alternative strategies – such as modifying electrolyte properties, introducing interfacial layers, or adopting lithium alloy anodes – may be required to mitigate dendrite growth and improve long-term reliability.
Yao’s custom air-free vessel has already been widely adopted. The technology has led to the launch of Solid Design Instruments LLC, a startup that has already sold eight units to national laboratories and major battery companies.
Photo: a pane of shattered glass Credit: Shutterstock
