The increase in cycle life requirements and duty-loads in electric vehicles along with battery energy storage systems have continued to put pressure on the search for precise and reliable battery control systems. Battery management systems are control systems composed of hardware as well as software that are made to ensure proper operation of lithium ion batteries. Despite the huge steps that have been made in the enhancement of the battery management systems technology, detrimental battery failures are still being recorded.
Lithium plating has been identified as the most detrimental occurrence in lithium ion batteries. It results in dendrite induced short-circuiting. This has led to massive losses, which affects battery industry and manufacturers’ reputation. It also poses a major safety concern to the battery users. Therefore, it is important to improve further battery monitoring. Advanced method to operando diagnose and predict battery degradation mechanisms and lithium-plating development will form the basis of these developments. This will be a challenging task, but will be a significant step towards battery monitoring.
Reference to the effects of lithium plating on the performance of lithium ion batteries as well as users’ safety, a lot of efforts have been put in trying to elucidate its effects further and to come up with its detection methods.
David Anseán, V.M. García, J.C. Viera, and M. González at University of Oviedo in Spain in collaboration with Matthieu Dubarry, A. Devie, B.Y. Liaw at University of Hawai’i demonstrated an analysis to operando identify and quantify lithium plating on graphite LiFePO4 cell. They tested the cell at ambient temperature implementing standard dynamic stress test driving schedule. They implemented a framework that merged both electrochemical and computer simulation methods. Incremental capacity evaluation was used to establish and trace reversible lithium plating and uncover the causes of cell degradation. Their research work is published in Journal of Power Sources.
The research team coupled the evaluation of the peak area and incremental capacity to establish and quantify the presence of a new phase transformation in the cell voltage signature. The phase occurred from the reversible lithium-plating occurrence. The researchers then analyzed the nature of lithium plating origin and observed that gradual degradation caused the cell to plate. The mechanistic model simulations allowed for operando identification of the ongoing aging modes, estimation of the reversible amount of lithium plating, and projection of half-cell degradation on both electrodes throughout the cycling.
The outcomes indicated that large loss of active material on delithiated negative electrode caused cell imbalance eventually. This resulted to overlithiate the negative electrode and subsequently induced lithium plating. Quantitative analysis also highlighted the effects of lithium plating. The loss of lithium inventory was raised by a factor of 4. The results of this study indicated the importance of tracking cell-aging mechanisms to predict, uncover and estimate lithium plating.
The researchers demonstrated that early detection of lithium plating comes with some benefits. First, it can be implemented in battery systems to curtail the duty-cycling scheme requirements, therefore, helps avoid further degradation and prolongs cycle-life. This straightforward, in situ, and cost effective method can be used to enhance battery management system functions for prognosis and diagnosis.
Their study also focused on the potential of the alawa toolbox developed by Matthieu Dubarry at University of Hawai’i, to forecast the impact of none only the main degradation mechanisms but also the reversible and irreversible parts of lithium plating. This framework can be helpful to researchers focusing on the correlation of the cell design parameters with normal battery degradation, such as loss of lithium inventory and loss of active material as well as abnormal degradation such as lithium plating occurrence.
Anseán, M. Dubarry, A. Devie, B.Y. Liaw, V.M. García, J.C. Viera, M. González. Operando lithium plating quantification and early detection of a commercial LiFePO4 cell cycled under dynamic driving schedule. Journal of Power Sources, volume 356 (2017), pages 36-46.
Go To Journal of Power Sources