Degradation Mechanism of O3-Type NaNi<sub>1/3</sub>Fe<sub>1/3</sub>Mn<sub>1/3</sub>O<sub>2</sub> Cathode Materials During Ambient Storage and Their In Situ Regeneration
Yang‐Kook Sun, Hong Wang, Dechao Meng, Xiaoqiao Li, Xiao‐Zhen Liao, Haiying Che, Guijia Cui, Fengping Yu, Weimin Yang, Linsen Li, Zi‐Feng Ma
Abstract
Sodium-ion batteries (SIBs) hold great promise for low-cost energy storage. Despite the major advances made in the material preparation and battery performance, air instability has become a bottleneck for the storage and electrode fabrication of O3-type NaNi1/3Fe1/3Mn1/3O2 (NFM), but the underlying mechanism remains elusive. Here we discovered that NFM loses Na+ ions during ambient storage and Na2CO3 “fibers” sprout from the particle surface, which caused the performance decay. We further demonstrated a facile resintering strategy to regenerate the NFM in situ. This work highlights the importance of stringent humidity control and provides the basis for designing surface-modification strategies.