Performance degradation and sealing failure analysis of pouch lithium-ion batteries under multi-storage conditions

Abstract

Due to its numerous advantages, lithium-ion batteries have been widely used in various fields. However, as the application scenarios expand, batteries often encounter adverse environments such as high temperature and high humidity during storage and usage. Faced with such conditions, batteries not only experience performance degradation but also the risk of leakage, posing a serious threat to battery safety. In order to investigate the influencing factors of battery performance degradation and the failure modes of battery leakage under harsh conditions, we conducted a study using a commercial LiCoO2/graphite pouch cell as the experimental object. We focused on studying the capacity degradation mechanism and sealing failure modes during the storage process under high temperature-low humidity and high temperature-high humidity conditions. The results revealed that compared to the cell under normal temperature-low humidity conditions, the remaining capacity and recovery capacity of the cell under high temperature-low humidity and high temperature-high humidity conditions has shown a certain degree of attenuation. Subsequently, we investigated the underlying mechanisms behind the performance degradation through a series of characterizations. Additionally, regarding the issue of leakage, we analyzed the outer sealing materials of the cell to identify potential pathways for external moisture ingress, aiming to provide references and support for enhancing battery safety in harsh environments.