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. 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. This article details a multi-year cycling study of commercial LiFePO4 (LFP), LiNixCoyAl1−x−yO2 (NCA), and LiNixMnyCo1−x−yO2 (NMC) cells, varying the discharge rate, depth of discharge (DOD), and environment temperature. The capacity and discharge energy retention, as well as the round-trip efficiency, were compared. 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 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. All cycling files have been made publicly available at batteryarchive.org, a recently developed repository for visualization and comparison of battery data, to facilitate future experimental and modeling efforts.

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Abstracr -We describe a series of unique self-stressing, reliability test structures suitable for investigation of reliability failure mechanisms f&ot-camers, electromigration, oxide breakdown) under realistic integrated circuit operating conditions. These shuctures contain DC-controlled, high-frequency on-chip oscillators, which stress test shuctures. As a result, high-frequency (>200 MHz) stresstesting can be performed using less expensive DC test systems. In particular, we performed hot-camer stress-testing at frequencies up to 230 MHz, which is the highest stress frequency reported for inverters. For the 1 pm technology examined, the quasi-static model accurately describes the degradation. We also present the statistical variation in high-frequency, hot-camer-induced degradation for the first time and show variations with temperature to be consistent with DC stress results. Since only DC test systems are needed, these structures provide a simple method to calibrate reliability simulators and characterize high-frequency reliability effects.