Park, Jae Yeol Kang, Hyun Beom Jeon, Dongmin Shim, Yoonsu Jo, Eunmi Hong, Yeoreum Gong, Sang Hyuk Yuk, Jong Min Lee, Chan-Woo Byun, Dongjin Kim, Hyung-Seok Kim, Seung Min Chang, Wonyoung 2025-11-20T23:59:10Z 2025-11-20T23:59:10Z 2025-11-11 2025-11 https://pubs.kist.re.kr/handle/201004/153547 We propose a mechanism of how Cu substitution in the O3-type sodium-ion battery cathode enhances its aqueous stability compared to the Co-doped O3-type cathode. The aqueous stability is closely associated with the crystal structural stability. Cu dopant allows electronic redistribution, leading to maintaining its oxidation state upon desodiation. It also mitigates changes in polyhedral volume of transition metal-O6, resulting in high structural stability upon desodiation. In contrast, the Co dopant is oxidized upon desodiation, inducing larger polyhedral volume variations. It finally entails structural instability of the Co-doped cathode, which can be exacerbated during vigorous desodiation. Therefore, in an aqueous environment, the Co-doped cathode experiences severe structural degradation to form OP4, Fd3m, and C2/m phases, retaining only 19% of Na-storing capability. In contrast, the Cu-doped cathode retains the original structure, thereby preserving 82% of its Na-storing capability. Our findings provide invaluable insights on resolving storage and handling issues of sodium-ion battery cathodes induced by their moisture sensitivity. English AMER CHEMICAL SOC Role of Cu Dopant in Improving the Structural Stability of O3-Type Sodium-Ion Battery Cathode: Mitigating Oxidation State Variation toward Reinforcing Aqueous Stability Article 10.1021/acsmaterialslett.5c01163 1 ACS Materials Letters, v.7, no.11, pp.3683 - 3691 ACS Materials Letters 7 11 3683 3691 N scie scopus 001594311000001 2-s2.0-105018736141 Materials Science, Multidisciplinary Materials Science Article