One of the challenges in the automotive industry is to provide fast charging of batteries. On the other hand, the safe operation of including low temperatures is indisputable. During cycling in such conditions, many undesirable phenomena may occur in the lithium-ion cell, such as low electrochemical performance of the system, e.g., high voltage drop, thermal accidents, capacity fade. As a result of these undesirable changes, the whole battery system degrades much faster. One of the most popular mechanisms mentioned in the literature is lithium deposition on the graphitic electrode side. It may cause safety failure of the battery, like a thermal runaway. Additionally, it is responsible for the capacity fade of the cell because of electrochemically active lithium consumption.
In literature, many methods are described that make the possible investigation of lithium deposition observation. However, they are mostly limited to the laboratory level. Furthermore, only a few reports of lithium plating in a commercial lithium-ion battery. Currently, for each cell, the charge-discharge conditions are established experimentally. The way of safe cycling of the battery is necessary to develop a proper fast charging scheme and extend battery life. Unfortunately, even a wide range of protections installed in the Battery Management System (BMS) do not prevent failures. This means that the methods are not ideal and need to be improved or optimized.
This work aims to select the universal methods for evaluating lithium deposition on the anode in the cells of different designs and materials. For this purpose, the batteries were cycled under different operating conditions that lithium deposition preferably occurs – low temperature or high current loads during charging. The application of numerous electrochemical methods and appropriate mathematical data processing made it possible. The conclusions on evaluating the lithium deposition phenomenon can be drawn under different operating conditions with the selection of the best detection methods.
The research confirmed that lithium plating could be observed at low temperatures and high C-rates. In comparison, high C-rates have a higher impact. What is more, the most appropriate and non-destructive method for lithium plating detection is analyzing the OCV curves and their derivatives. As we can see, this method is applicable in coin cells and cylindrical cells. Lithium plating occurs in cells working under extreme conditions exceeding much above specification.
Moreover, the Li platting occurs with failure of internal cell construction, as well. This was observed mainly in the case of cylindrical cells, where about 15 pieces were examined in different extreme conditions. Finally, the lithium plating was observed only for one experimental condition that were not even extreme in all testing protocol.