材料科学
阴极
氟
高原(数学)
电压
高压
化学工程
离子
光电子学
纳米技术
电气工程
化学
冶金
数学分析
工程类
有机化学
数学
作者
Liang Deng,Fu‐Da Yu,Xia Yang,Yunshan Jiang,Xu–Lei Sui,Lei Zhao,Xianghui Meng,Lan‐Fang Que,Zhen‐Bo Wang
出处
期刊:Nano Energy
[Elsevier]
日期:2021-04-01
卷期号:82: 105659-105659
被引量:82
标识
DOI:10.1016/j.nanoen.2020.105659
摘要
Na3V2(PO4)2F3 is a promising cathode candidate for sodium ion batteries due to its high working voltage. However, an “unknown” low-voltage plateau around ~3.3 V lowers its operating voltage and puzzles researchers. Herein, the reasons for its appearance are explored. It is found that the formation of the low-voltage plateau originates from the extra-generated [VO6] induced by the fluorine loss during the synthesis. To enable better performance, a feasible strategy of stabilizing fluorine is proposed to eliminate the low-voltage plateau. It is demonstrated that this strategy can effectively guarantee the existence of fluorine and modulate the local electronic structure of V to maintain [VO4F2] in Na3V2(PO4)2F3 phase, thus eliminating the undesirable plateau and achieving an operating-voltage increase of ~100 mV. Moreover, the enhanced structural stability and kinetics of the optimized Na3V2(PO4)2F3 cathode are confirmed by in-situ XRD. As expected, the Na3V2(PO4)2F3 cathode delivers higher energy density (446.4 Wh kg−1), better rate capability and longer cycling performance (89.2%@30 C after 1000 cycles). Furthermore, its excellent adaptability to wide temperature range (−25 °C–55 °C) and strong competence in Na3V2(PO4)2F3||hard carbon full-cell are verified. These excellent properties further qualify Na3V2(PO4)2F3 as a competitive cathode for sodium ion batteries.
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