title: Carbon-Coated Na3.32Fe2.34(P2O7)2Cathode Material for High-Rate and Long-Life Sodium-Ion Batteries.
abstract: Rechargeable sodium-ion batteries are proposed as the most appropriate alternative to lithium batteries due to the fast consumption of the limited lithium resources. Due to their improved safety, polyanion framework compounds have recently gained attention as potential candidates. With the earth-abundant element Fe being the redox center, the uniform carbon-coated Na3.32Fe2.34(P2O7)2/C composite represents a promising alternative for sodium-ion batteries. The electrochemical results show that the as-prepared Na3.32Fe2.34(P2O7)2/C composite can deliver capacity of ≈100 mA h g-1at 0.1 C (1 C = 120 mA g-1), with capacity retention of 92.3% at 0.5 C after 300 cycles. After adding fluoroethylene carbonate additive to the electrolyte, 89.6% of the initial capacity is maintained, even after 1100 cycles at 5 C. The electrochemical mechanism is systematically investigated via both in situ synchrotron X-ray diffraction and density functional theory calculations. The results show that the sodiation and desodiation are single-phase-transition processes with two 1D sodium paths, which facilitates fast ionic diffusion. A small volume change, nearly 100% first-cycle Coulombic efficiency, and a pseudocapacitance contribution are also demonstrated. This research indicates that this new compound could be a potential competitor for other iron-based cathode electrodes for application in large-scale Na rechargeable batteries.
authors.affiliation: Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Innovation Campus, Squires Way, North Wollongong, NSW, 2522, Australia.
authors.forename: Mingzhe
authors.initials: M
authors.lastname: Chen
authors.affiliation: School of Computer Science and Technology, University of South China, Hengyang, 421001, China.
authors.forename: Lingna
authors.initials: L
authors.lastname: Chen
authors.affiliation: Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Innovation Campus, Squires Way, North Wollongong, NSW, 2522, Australia.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Innovation Campus, Squires Way, North Wollongong, NSW, 2522, Australia.
authors.forename: Qiannan
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Innovation Campus, Squires Way, North Wollongong, NSW, 2522, Australia.
authors.forename: Binwei
authors.initials: B
authors.lastname: Zhang
authors.affiliation: School of Chemical Engineer and Australian Institute of Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD, 4072, Australia.
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, 3168, Australia.
authors.forename: Qinfen
authors.initials: Q
authors.lastname: Gu
authors.affiliation: Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Innovation Campus, Squires Way, North Wollongong, NSW, 2522, Australia.
authors.forename: Jian-Li
authors.initials: JL
authors.lastname: Wang
authors.affiliation: School of Chemical Engineer and Australian Institute of Bioengineering and Nanotechnology, University of Queensland, Brisbane, QLD, 4072, Australia.
authors.forename: Lian-Zhou
authors.initials: LZ
authors.lastname: Wang
authors.affiliation: College of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Guo
authors.affiliation: Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Innovation Campus, Squires Way, North Wollongong, NSW, 2522, Australia.
authors.forename: Shu-Lei
authors.initials: SL
authors.lastname: Chou
authors.affiliation: Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Innovation Campus, Squires Way, North Wollongong, NSW, 2522, Australia.
authors.forename: Shi-Xue
authors.initials: SX
authors.lastname: Dou
keywords: carbon coatings; cathode materials; cycling stability; polyanion frameworks; sodium-ion batteries