Hybrid functional study of the NASICON-type Na3V2(PO4)3: crystal and electronic structures, and polaron-Na vacancy complex diffusion.
The crystal and electronic structures, electrochemical properties and diffusion mechanism of NASICON-type Na3V2(PO4)3 have been investigated based on the hybrid density functional Heyd-Scuseria-Ernzerhof (HSE06). A polaron-Na vacancy complex model for revealing the diffusion mechanism is proposed for the first time in the field of Na-ion batteries. The bound polaron is found to favorably form at the first nearest V site to the Na vacancy. Consequently, the movement of the Na vacancy will be accompanied by the polaron. Three preferable diffusion pathways are revealed; these are two intra-layer diffusion pathways and one inter-layer pathway. The activation barriers for the intra-layer and inter-layer pathways are 353 meV and 513 meV, respectively. For further comparison, the generalized gradient approximation with an onsite Coulomb Hubbard U (GGA+U) is also employed.
Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan. BUI.Thikieumy@nims.go.jp and Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan. sokada@comas.frsc.tsukuba.ac.jp.
Kieu My
KM
Bui
Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan. divan@mat.eng.osaka-u.ac.jp.
Van An
VA
Dinh
Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan. sokada@comas.frsc.tsukuba.ac.jp.
Susumu
S
Okada
Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan. BUI.Thikieumy@nims.go.jp and Computational Materials Science Unit (CMSU), National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan. OHNO.Takahisa@nims.go.jp.
Takahisa
T
Ohno