Degradation of Commercial Lithium-Ion Cells as a Function of Chemistry and Cycling Conditions

TLDR

Li‑ion batteries are increasingly used to support grid resilience and renewable integration, yet choosing the right chemistry is difficult because public data comparing common off‑the‑shelf chemistries under identical conditions is scarce. This study investigates how discharge rate, depth of discharge, and temperature affect the degradation of commercial LFP, NCA, and NMC cells, and compares the results to prior work to uncover universal trends and quantify performance variability. Over multiple years, the authors cycled LFP, NCA, and NMC cells at varied rates, DODs, and temperatures, measuring capacity, energy retention, and round‑trip efficiency, and benchmarked the data against similar studies. The results show that even within manufacturer specifications, cycling conditions can change the time to 80 % capacity by thousands of hours and cycles across chemistries, and the complete dataset is now publicly available at batteryarchive.org.

Abstract

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 LiFePO 4 (LFP), LiNi x Co y Al 1−x−y O 2 (NCA), and LiNi x Mn y Co 1−x−y O 2 (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.