Decoupling the air sensitivity of Na-layered oxides
Yang Yang, Zaifa Wang, Congcong Du, Daniel Kuok Ho Tang, Xinyan Li, Siyuan Wu, Xiaowei Li, Xiao Zhang, Xubin Wang, Yaoshen Niu, Feixiang Ding, Xiaohui Rong, Yaxiang Lu, Nian Zhang, Juping Xu, Ruijuan Xiao, Qinghua Zhang, Xuefeng Wang, Wen Yin, Junmei Zhao, Liquan Chen, Jianyu Huang, Yong‐Sheng Hu
Abstract
Air sensitivity remains a substantial barrier to the commercialization of sodium (Na)-layered oxides (NLOs). This problem has puzzled the community for decades because of the complexity of interactions between air components and their impact on both bulk and surfaces of NLOs. We show here that water vapor plays a pivotal role in initiating destructive acid and oxidative degradations of NLOs only when coupled with carbon dioxide or oxygen, respectively. Quantification analysis revealed that reducing the defined cation competition coefficient (η), which integrates the effects of ionic potential and sodium content, and increasing the particle size can enhance the resistance to acid attack, whereas using high-potential redox couples can eliminate oxidative degradation. These findings elucidate the underlying air deterioration mechanisms and rationalize the design of air-stable NLOs.