University of Maryland Study Reveals How Battery Aging Mechanism Works

Researchers at the University of Maryland have uncovered the fundamental mechanism behind aging in next-generation high-energy lithium-ion batteries, offering a clear roadmap for designing batteries that deliver both high energy density and long life.

Distinguished University Professor Chunsheng Wang in the Department of Chemical and Biomolecular Engineering and Weiran Zhang Ph.D. ’24, an assistant professor in Nanyang Technological University, published a study in Nature Energy that systematically reveals the mechanism of calendar aging in silicon anodes, which could accelerate the development of long-term reliable electric vehicles (EVs) and future energy-storage technologies.

As electric vehicles and energy storage systems rapidly expand worldwide, battery performance has become a critical bottleneck. While higher energy density is essential for longer driving range and lower cost, it often comes at the expense of stability and lifetime. Silicon anodes, which can store nearly ten times more capacity than today’s graphite anodes, present challenges that prevent widespread commercial adoption, and that also raise questions about battery longevity during storage, known as calendar life.

They often degrade faster than their graphite counterparts, even when they are not being used—a problem that has drawn significant attention from both industry and academia. Unlike cycling life, which tracks how many charge-discharge cycles a battery can endure, calendar life measures how batteries degrade simply over time, which is particularly relevant for electric vehicle batteries, which may sit unused for long periods and are costly or difficult to replace.

In the study, Wang and Zhang proved that both cycling aging and calendar aging in silicon anodes originate from the same root cause: instability of the solid electrolyte interphase, the thin protective layer that forms between the electrode and the electrolyte, but with different emphases. This ends a long-standing debate in battery research over whether improving cycling performance automatically leads to better storage stability.

“This work lays a strong foundation for the development of low-cost, long-term reliable, high-energy lithium-ion batteries for future electric vehicles and energy-storage systems,” said Wang.

Beyond explaining why silicon anodes fail, the research also offers a practical tool for battery development, demonstrating that cycling Coulombic Efficiency can serve as a powerful early-stage indicator of calendar aging, allowing researchers to quickly screen materials and electrolytes before long-term storage tests are completed. When combined with traditional leakage-current measurements, this approach significantly improves the reliability of lifetime prediction.

Published February 6, 2026