Revealing the Fast and Durable Na+ Insertion Reactions in a Layered Na3Fe3(PO4)4 Anode for Aqueous Na-Ion Batteries

Shen Qiu; Marcos Lucero; Xianyong Wu; Qi Wang; Maoyu Wang; Yan Wang; Widitha S Samarakoon; Meilani R Bolding; Zhenzhen Yang; Yaqin Huang; Zhichuan J Xu; Meng Gu; Zhenxing Feng

doi:10.1021/acsmaterialsau.1c00035

Revealing the Fast and Durable Na⁺ Insertion Reactions in a Layered Na₃Fe₃(PO₄)₄ Anode for Aqueous Na-Ion Batteries

ACS Mater Au. 2021 Oct 26;2(1):63-71. doi: 10.1021/acsmaterialsau.1c00035. eCollection 2022 Jan 12.

Authors

Affiliations

¹ School of Chemical, Biological, and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331, United States.
² Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
³ Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States.
⁴ Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing 10029, China.
⁵ School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore.

Abstract

Aqueous sodium-ion batteries represent a promising approach for stationary energy storage; however, the lack of appropriate anode materials has substantially retarded their development. Herein, we demonstrated an iron-based phosphate material of Na₃Fe₃(PO₄)₄ as an inexpensive and efficacious anode alternative. While the Fe³⁺/Fe²⁺ redox couple renders a two-Na-insertion reaction with desirable potentials, its unique layered structure further facilitates the Na-insertion kinetics and reversibility. Consequently, this electrode exhibits an appealing Na-insertion performance, with a reversible capacity of ∼83 mAh g^-1, suitable anode potential of -0.4 V vs Ag/AgCl, excellent rate capability of 200 C, and outstanding cycling of 6000 cycles. Utilizing operando synchrotron X-ray diffraction and X-ray absorption spectroscopy, we revealed the structural evolution of the Na₃Fe₃(PO₄)₄ anode during the two-electron reaction, where the extremely small volume expansion (∼3%) enables its fast-charging and long-cycling capability. Our work suggests new considerations of developing versatile iron phosphate compounds as appealing anode materials for energy storage in aqueous electrolytes.