Realizing outstanding electrochemical performance with Na3V2(PO4)2F3 modified with an ionic liquid for sodium-ion batteries. Issue 22 (11th May 2022)

• Record Type: Journal Article
• Authors: Yu, Xiaobo; Lu, Tianyi; Li, Xiaokai; Qi, Jiawei; Yuan, Luchen; Man, Zu; Zhuo, Haitao
• Is Part Of: RSC advances. Volume 12:Issue 22(2022)
• Page Start: 14007
• Page End: 14017
• Publication Date: 2022-05-11
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d2ra01292h
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : An ionic liquid is used as a new nitrogen and boron source to synthesize nitrogen–boron co-doped carbon-coated Na3 V2 (PO4 )2 F3 (NVPF-CNB). Abstract : Na3 V2 (PO4 )2 F3 is a typical NASICON structure with a high voltage plateau and capacity. Nevertheless, its applications are limited due to its low conductivity and poor rate performance. In this study, nitrogen–boron co-doped carbon-coated Na3 V2 (PO4 )2 F3 (NVPF-CNB) was prepared by a simple sol–gel method using an ionic liquid (1-vinyl-3-methyl imidazole tetrafluoroborate) as a source of nitrogen and boron for the first time. The morphology and electrochemical properties of NVPF-CNB composites were investigated. The results show that a nitrogen–boron co-doped carbon layer could increase the electron and ion diffusion rate, reduce internal resistance, and help alleviate particle agglomeration. NVPF-CNB-30 exhibited better rate performance under 5C and 10C charge/discharge with initial reversible capacities of 99 and 90 mA h g −1, respectively. Furthermore, NVPF-CNB-30 illustrates excellent cyclic performance with the capacity retention rate reaching 91.9% after 500 cycles at 5C, as well as a capacity retention rate of about 95.5% after 730 cycles at 10C. The evolution of the material's structure during charge/discharge processes studied by in situ X-ray diffraction confirms the stable structure of nitrogen–boron co-doped carbon-coated Na3 V2 (PO4 )2 F3 . Co-doping of nitrogen and boron also provides more active sites on the surface of Na3 V2 (PO4 )2 F3, revealing a new strategy for the modification of sodium-ion batteries.