title: Insights into the Effects of Zinc Doping on Structural Phase Transition of P2-Type Sodium Nickel Manganese Oxide Cathodes for High-Energy Sodium Ion Batteries.
abstract: P2-type sodium nickel manganese oxide-based cathode materials with higher energy densities are prime candidates for applications in rechargeable sodium ion batteries. A systematic study combining in situ high energy X-ray diffraction (HEXRD), ex situ X-ray absorption fine spectroscopy (XAFS), transmission electron microscopy (TEM), and solid-state nuclear magnetic resonance (SS-NMR) techniques was carried out to gain a deep insight into the structural evolution of P2-Na0.66Ni0.33-xZnxMn0.67O2 (x = 0, 0.07) during cycling. In situ HEXRD and ex situ TEM measurements indicate that an irreversible phase transition occurs upon sodium insertion-extraction of Na0.66Ni0.33Mn0.67O2. Zinc doping of this system results in a high structural reversibility. XAFS measurements indicate that both materials are almost completely dependent on the Ni(4+)/Ni(3+)/Ni(2+) redox couple to provide charge/discharge capacity. SS-NMR measurements indicate that both reversible and irreversible migration of transition metal ions into the sodium layer occurs in the material at the fully charged state. The irreversible migration of transition metal ions triggers a structural distortion, leading to the observed capacity and voltage fading. Our results allow a new understanding of the importance of improving the stability of transition metal layers.
authors: State Key Laboratory of Physical Chemistry of Solid Surfaces, and Department of Chemistry, Xiamen University , Xiamen, Fujian 361005, China.|Collaborative Innovation Center of Renewable Energy Materials, Guangxi University , Nanning, Guangxi 530004, China.
authors: Xuehang
authors: X
authors: Wu
authors: Chemical Sciences and Engineering Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors: Gui-Liang
authors: GL
authors: Xu
authors: State Key Laboratory of Physical Chemistry of Solid Surfaces, and Department of Chemistry, Xiamen University , Xiamen, Fujian 361005, China.
authors: Guiming
authors: G
authors: Zhong
authors: School of Energy Research, Xiamen University , Xiamen 361005, China.
authors: Zhengliang
authors: Z
authors: Gong
authors: State Key Laboratory of Physical Chemistry of Solid Surfaces, and Department of Chemistry, Xiamen University , Xiamen, Fujian 361005, China.
authors: Matthew J
authors: MJ
authors: McDonald
authors: State Key Laboratory of Physical Chemistry of Solid Surfaces, and Department of Chemistry, Xiamen University , Xiamen, Fujian 361005, China.
authors: Shiyao
authors: S
authors: Zheng
authors: National High Magnetic Field Laboratory , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States.
authors: Riqiang
authors: R
authors: Fu
authors: Chemical Sciences and Engineering Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors: Zonghai
authors: Z
authors: Chen
authors: Chemical Sciences and Engineering Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
authors: Khalil
authors: K
authors: Amine
authors: State Key Laboratory of Physical Chemistry of Solid Surfaces, and Department of Chemistry, Xiamen University , Xiamen, Fujian 361005, China.|School of Energy Research, Xiamen University , Xiamen 361005, China.
authors: Yong
authors: Y
authors: Yang
keywords: Zn doping; cathode material; sodium ion battery; sodium nickel manganese oxide; structural transition