Mixed-metal borate FeVBO4 of tunnel structure: Synthesis and electrochemical properties in lithium and sodium ion batteries

作者：Dong, Maolin; Kuang, Quan^*; Zeng, Xinxuan; Chen, Lei; Zhu, Jianzhong; Fan, Qinghua; Dong, Youzhong; Zhao, Yanming

来源：Journal of Alloys and Compounds, 2020, 812: 152165.

DOI：10.1016/j.jallcom.2019.152165

• FeVBO4
• Mixed-metal borate
• Crystal structure
• Electrochemical performance
• Lithium/sodium ion batteries

Transition borates exhibit various functions due to their diverse components and structures. Herein, a new mixed-metal borate, FeVBO4 with rhombic and triangular tunnels for ionic transportation, is first synthesized at 800 degrees C subsequent to a sol-gel routine. The new compound FeVBO4 crystallizes in an orthorhombic space group (Pnma, #62), with cell parameters of a = 9.2367(5) angstrom, b = 3.1772(1) angstrom, and c = 9.3912(6) angstrom. Furthermore, the electrochemical properties of carbon-coated FeVBO4 (FeVBO4/carbon) is evaluated as intercalated anode for rechargeable Li and Na batteries. The Na storage of FeVBO4 /carbon via conversion reaction exhibits very low reversible capacity (46 mAh g(-1)). However, the Li storage of FeVBO4/carbon revealing high capacity is worth to investigate. The Li ions first insert the rhombic tunnels to form the LixFeVBO4 (0 < x <= 1) solid solution, and then squeeze into the triangular tunnel and activate a conversion reaction accomplished by delivering a high discharge capacity of 621.6 mAh g(-1) (theoretical capacity 737.9 mAh g(-1)) and showing a reversible recharge capacity of 387.3 mAh g(-1). Our study has unlocked the great potential of borate-type anode in rechargeable batteries, and the new compound FeVBO4 with unique structure and mixed metallic elements could be extended to other application area.