Innovative Imaging Technique Unveils Lithium-Metal Battery Degradation Mechanisms

In a groundbreaking study, researchers at the California NanoSystems Institute (CNSI) at UCLA have developed an innovative imaging technique that captures lithium-metal batteries in action, revealing vital details about their capacity degradation. This research, published in the journal Science Advances on June 14, 2025, marks a significant step in understanding how these batteries function under real-world conditions, potentially paving the way for their future commercialization.

Lithium-metal batteries are regarded for their potential to offer energy densities twice that of conventional lithium-ion batteries, which currently dominate the market. However, their practical application has been hindered by limited cycling stability, with research indicating that the best-performing lithium-metal batteries can only endure about 200 charging cycles compared to thousands for lithium-ion counterparts.

According to Yuzhang Li, an assistant professor of chemical and biomolecular engineering at UCLA and the corresponding author of the study, "China currently controls nearly 80% of the lithium-ion battery supply chain, making it imperative for the U.S. to advance lithium-metal battery technology to remain competitive in the electric vehicle and energy storage markets."

The new imaging method, known as electrified cryogenic electron microscopy (eCryoEM), allows researchers to visualize the internal processes of batteries as they charge, providing unprecedented insights into the formation of corrosion layers that can impede performance. Traditional imaging techniques have largely relied on postmortem analyses, thus failing to capture dynamic electrochemical reactions as they occur.

Li explains, "Our technique enables us to freeze the battery during the charging process, effectively allowing us to observe the growth of the corrosion film over time. We can analyze how quickly this layer forms and its impact on battery performance. By comparing different electrolyte chemistries, we discovered that the reactivity of the electrolyte plays a critical role in determining the performance and longevity of lithium-metal batteries."

The study found that the performance of lithium-metal batteries is significantly influenced by the characteristics of the corrosion layer formed during operation. High-performing electrolytes resulted in slower corrosion film growth during the early stages of charging, which is crucial for extending battery life. This insight suggests that enhancing the inertness of the electrolyte could be a key focus for future battery designs.

Dr. Chongzhen Wang, a doctoral student at UCLA and co-first author of the study, noted, "Our findings challenge the prevailing notion that electron diffusion is the primary factor affecting performance. Instead, it is the reactivity of the electrolyte that fundamentally limits battery life at early charging stages. This opens up new avenues for research and development in battery technology."

The implications of this research extend beyond battery technology. The eCryoEM technique holds promise for applications in various fields, including neuroscience, as Li suggests, "Understanding the molecular-scale processes in batteries could also inform our studies of dynamic biological systems, such as neuronal activity, by allowing us to visualize cellular responses in real-time."

As the demand for efficient energy storage solutions continues to rise, advancements like these are crucial for ensuring that lithium-metal batteries can eventually replace their lithium-ion counterparts. The ongoing research at CNSI, supported by notable funding including a Packard Fellowship, aims to refine this technology and explore its applications further.

In summary, the successful application of eCryoEM not only enhances our understanding of lithium-metal battery behavior but also sets the stage for future innovations that could significantly impact the energy storage landscape. The pressing challenge remains: how to leverage these insights to create batteries that are not only more powerful but also more durable and efficient in real-world settings.