To maximize battery life, high storage SoCs corresponding to low anode potential should be avoided. Aging mechanisms induced by high cell potential, such as electrolyte oxidation or transition-metal dissolution, seem to play only a minor role. In the high SoC regime where the graphite anode is lithiated more than 50%, the low anode potential accelerates the loss of cyclable lithium, which in turn distorts the electrode balancing. Lower anode potentials, which aggravate electrolyte reduction and thus promote solid electrolyte interphase growth, have been identified as the main driver of capacity fade during storage. Furthermore, our study reveals the high impact of the graphite electrode on calendar aging. Differential voltage analyses confirm that the capacity fade is mainly caused by a shift in the electrode balancing. Instead, plateau regions, covering SoC intervals of more than 20%–30% of the cell capacity, are observed wherein the capacity fade is similar. Our study demonstrates that calendar aging does not increase steadily with the SoC. Three types of 18650 lithium-ion cells, containing different cathode materials, have been examined. In this study, the calendar aging of lithium-ion batteries is investigated at different temperatures for 16 states of charge (SoCs) from 0 to 100%. All cycling files have been made publicly available at, a recently developed repository for visualization and comparison of battery data, to facilitate future experimental and modeling efforts. The degradation of cells in this study was compared to that of similar cells in previous studies to identify universal trends and to provide a standard deviation for performance. Even when operated within manufacturer specifications, the range of cycling conditions had a profound effect on cell degradation, with time to reach 80% capacity varying by thousands of hours and cycle counts among cells of each chemistry. The capacity and discharge energy retention, as well as the round-trip efficiency, were compared.
This article details a multi-year cycling study of commercial LiFePO 4 (LFP), LiNi xCo yAl 1−x−yO 2 (NCA), and LiNi xMn 圜o 1−x−yO 2 (NMC) cells, varying the discharge rate, depth of discharge (DOD), and environment temperature. However, appropriate selection of cells for different applications is difficult due to limited public data comparing the most commonly used off-the-shelf Li-ion chemistries under the same operating conditions. Energy storage systems with Li-ion batteries are increasingly deployed to maintain a robust and resilient grid and facilitate the integration of renewable energy resources.
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