In recent years, sodium-ion batteries (SIB) have become of great interest in energy storage systems. SIBs offer advantages, including the availability of raw materials, the potential for lower costs, and the possibility of discarding copper as the anode collector material. While several works investigate the calendric and cyclic aging of lithium-ion batteries (Schmalstieg et al. 2014; Keil et al. 2016; Naumann et al. 2020; Gasper et al. 2023), a systematic investigation of the calendric and cyclic aging of SIBs is still missing.
Previous studies suggest that SIBs can achieve long cyclic lifetimes even under demanding conditions such as 100% depth of discharge (DOD) and high current. These cells demonstrated approximately 1200 equivalent full cycles before experiencing sudden failure (Laufen et al. 2024). Using cells from the same manufacturer in the same format but a different production batch, our observations show, to some extent, different results .
In this work, we investigate the influence of various factors on cyclic and calendric aging of SIBs with layered metal oxide cathode and hard carbon anode. For cyclic aging, the mean state of charge (SOC), DOD, and the C-Rate were systematically varied to obtain their respective influence on cell aging. Calendric aging was investigated by storing cells at two temperatures and various SOCs. To exclude statistical errors and cell-to-cell variance influence, each test point was tested with three cells. Our research includes a post-mortem analysis to further analyze the aging mechanisms. Providing insights into the impact of operating conditions on cell aging for SIBs, this work aims to deepen understanding of the factors affecting sodium-ion battery aging, thereby contributing to the development of more efficient and durable energy storage solutions.