Revealing high-temperature storage degradation mechanism in LiNi₀.₅Mn₁.₅O₄//graphite pouch cell

• Published in: Journal of energy storage Vol. 121; p. 116591
• Main Authors: Shen, Caiyan, Zeng, Yuexi, Wu, Qi, Cao, Yanbing, Peng, Zhongdong, Xue, Zhichen, Zhang, Bin, Du, Ke
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.06.2025
• Subjects: Calendar life; High voltage cathode; High-temperature storage; LiNi₀.₅Mn₁.₅O₄//graphite pouch cell; Surface analysis; High-temperature storage; Calendar life; High voltage cathode; LiNi₀.₅Mn₁.₅O₄//graphite pouch cell; Surface analysis
• ISSN: 2352-152X
• DOI: 10.1016/j.est.2025.116591

LiNi₀.₅Mn₁.₅O₄ (LNMO) is a promising lithium-ion cathode material with high energy density and low cost, yet it has not been widely adopted for large-scale applications. A major challenge is its poor high-temperature storage performance, leading to a substantial degradation of calendar life. In this study, we focus on practical Ah-level LNMO//Graphite (LNMO//Gr) pouch cells, and subject them to high-temperature storage abuse with fully charged conditions. Here in, a combination of advanced characterization methods is employed to investigate the changes occurring at different scales during storage. The results indicate that the cathode undergoes severe mechanical degradation including crack propagation and subsequent particle fragmentation post storage. Mechanical failure leads to increased cathode interface exposure, enhancing the catalytic effect of transition metals (TM) exacerbating the oxidation of the electrolyte. These decomposed by-products re-dissolve into the electrolyte and continuously migrate toward the anode and reduce at surface, which destroys the origin solid electrolyte interphase (SEI) layer. The side reactions at the cathode/electrolyte/anode interfaces persist throughout the storage process and collectively contributing to the accelerated degradation and shortened calendar life of the cell. This work highlights the significant impact of interfacial side reactions between the various components of LNMO//Gr pouch cells on the calendar life. •Using practical Ah-level LNMO//Graphite cell as research object.•Each component of pouch cell was analyzed separately.•Revealing how the degradation on the cathode and anode lead to the failure of the pouch cell.