Researchers at Stanford University have developed an extremely thin silver layer for solid electrolytes that enhances resistance to cracking.
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If successfully scaled, the technology could advance both the safety and durability of lithium metal batteries. The study was published in Nature Materials.
A solid electrolyte, situated between the opposing electrodes of a battery, should, in theory, facilitate a rechargeable lithium metal battery that is safer with significantly greater energy density and a much faster charge rate than the lithium-ion batteries currently available on the market.
For many years, researchers and engineers have investigated various approaches to unlock the substantial potential of lithium metal batteries. A persistent challenge with solid, crystalline electrolytes is the formation of tiny fissures that expand during operation, ultimately leading to battery failure.
In this study, the researchers, expanding on their three-year-old findings that detailed the formation and growth of these minute imperfections, have found that annealing a very thin layer of silver on the surface of the solid electrolyte significantly addresses the issue.
The silver coating enhances the electrolyte's surface strength fivefold against fractures caused by mechanical stress. It reduces the susceptibility of existing imperfections to lithium infiltration, particularly during rapid recharging, which transforms the nano fissures into nano crevices, eventually leading to battery failure.
The solid electrolyte that we and others are working on improving is a kind of ceramic that allows the lithium-ions to shuttle back and forth easily, but it’s brittle. On an incredibly small scale, it’s not unlike ceramic plates or bowls you have at home that have tiny cracks on their surfaces.
Wendy Gu, Associate Professor and Study Senior Author, Mechanical Engineering, Stanford University
“A real-world solid-state battery is made of layers of stacked cathode-electrolyte-anode sheets. Manufacturing these without even the tiniest imperfections would be nearly impossible and very expensive. We decided a protective surface may be more realistic, and just a little bit of silver seems to do a pretty good job,” said Gu.
Silver-Lithium Switch
Previous investigations conducted by various scientists explored the application of metallic silver coatings on the identical solid electrolyte material, referred to as "LLZO" due to its composition of lithium, lanthanum, and zirconium atoms, along with oxygen, which is the focus of the current study.
While prior research used metallic silver to enhance battery efficiency, the present study employed a dissolved form of silver that has lost an electron (Ag+). This dissolved, charged form of silver – in contrast to metallic, solid silver – plays a direct role in reinforcing the ceramics against the formation of cracks.
The researchers applied a 3-nanometer-thick layer of silver onto the surfaces of LLZO, subsequently heating the samples to a temperature of 300 °C (572 °F). During the heating process, the silver atoms infiltrated the surface of the electrolyte, swapping positions with significantly smaller lithium atoms to a depth ranging from 20 to 50 nm.
The silver remained in the form of positively charged ions rather than reverting to metallic silver, which the scientists believe is crucial in mitigating crack formation. In areas where imperfections are present, the existence of some positive silver ions also inhibits lithium from penetrating and developing harmful branches within the electrolyte.
Our study shows that nanoscale silver doping can fundamentally alter how cracks initiate and propagate at the electrolyte surface, producing durable, failure-resistant solid electrolytes for next-generation energy storage technologies.
Xin Xu, Assistant Professor, Engineering, Arizona State University
Xu led the research as a postdoctoral scholar at Stanford.
“This method may be extended to a broad class of ceramics. It demonstrates ultrathin surface coatings can make the electrolyte less brittle and more stable under extreme electrochemical and mechanical conditions, like fast charging and pressure,” said Xu, one of the researchers at Stanford working under Professor William Chueh, senior author of the study and director of the Precourt Institute for Energy.
Using a specialized probe in a scanning electron microscope, the researchers assessed the force required to fracture the surface. The silver-treated solid electrolyte necessitated nearly five times the pressure to break compared to the untreated material.
Looking Ahead
The experiments have been conducted using small test samples instead of complete battery systems. The researchers are currently applying a silver-based surface treatment to full lithium-metal batteries to evaluate the coating's performance under real-world conditions, including repeated fast charging and prolonged use.
The team is investigating various techniques for applying mechanical pressure at different angles, which could potentially enhance battery longevity. They are also examining strategies to prevent failures in additional types of solid electrolytes, such as those derived from sulfur, which may offer further advantages, such as enhanced chemical stability with lithium.
The potential application of these discoveries to emerging sodium-based batteries presents an intriguing opportunity to help mitigate supply-chain issues related to lithium-based batteries.
Silver is not the sole option, according to the researchers. Initial tests with other, more affordable metals, such as copper, have yielded promising results. Collectively, these findings indicate a novel and adaptable approach to reinforcing the delicate materials that may be essential for the development of next-generation batteries.
Journal Reference:
Xu, X., et al. (2026) Heterogeneous doping via nanoscale coating impacts the mechanics of Li intrusion in brittle solid electrolytes. Nature Materials. DOI: 10.1038/s41563-025-02465-7.