Researchers Yang Wang, Marta Zagorowska, and Riccardo M. G. Ferrari from the Department of Energy Technology at Eindhoven University of Technology have developed a new method for estimating the capacity of lithium-ion (Li-ion) batteries, which are widely used in electric vehicles (EVs) and other energy storage applications. Their work, published in the Journal of The Electrochemical Society, aims to address the limitations of conventional capacity estimation methods.
Currently, estimating the capacity of Li-ion batteries often requires extensive testing and complete charge or discharge cycles, which can be time-consuming and costly. The researchers have proposed a novel approach that leverages the open-circuit voltage (OCV) test, a simpler and more efficient process. Their method can estimate battery capacity using just one cycle of the OCV test and can even work with partial charge or discharge data. This is a significant improvement over traditional methods that require full cycles and extensive datasets.
The key to this new method is an observed invariance property in the OCV versus state of charge relationship across aging cycles. This means that the relationship between OCV and state of charge remains consistent over time, despite the battery aging. By exploiting this property, the researchers can estimate the battery’s capacity by solving an OCV alignment problem using only the OCV and discharge capacity data from the battery.
The researchers also demonstrated that their method can be combined with OCV identification algorithms to estimate capacity from dynamic discharge data, eliminating the need for dedicated data collection tests. This makes the method even more practical for real-world applications.
Simulation results showed that the method is highly accurate, achieving a mean absolute relative error of just 0.85% in capacity estimation across 12 samples from 344 aging cycles. This level of accuracy is crucial for ensuring the reliable operation of Li-ion batteries in EVs and other energy storage systems.
The practical applications of this research are significant for the energy sector. By providing a more efficient and accurate way to estimate battery capacity, this method could help improve the performance and longevity of energy storage systems. It could also reduce the costs associated with battery testing and maintenance, making Li-ion batteries a more viable option for a wider range of applications. The research was published in the Journal of The Electrochemical Society.
This article is based on research available at arXiv.