{"title":"Optimizing the Electron Spin States of Na4Fe3(PO4)2P2O7 Cathodes via Mn/F Dual-Doping for Enhanced Sodium Storage","authors":"Yukun Xi, Xiaoxue Wang, Hui Wang, Mingjun Wang, Guangjin Wang, Junqi Peng, Ningjing Hou, Xing Huang, Yanyan Cao, Zihao Yang, Dongzhu Liu, Xiaohua Pu, Guiqiang Cao, Ruixian Duan, Wenbin Li, Jingjing Wang, Kun Zhang, Kaihua Xu, Jiujun Zhang, Xifei Li","doi":"10.1002/adfm.202309701","DOIUrl":null,"url":null,"abstract":"<p>A NASICON-type Mn/F dual-doping Na<sub>4</sub>Fe<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>P<sub>2</sub>O<sub>7</sub> cathode material is successfully synthesized via a spray drying method. A medium-spin of Fe is measured by DFT calculation, X-ray absorption near edge structure (XANES), temperature-dependent magnetization susceptibility (M−T) measurement, and electron paramagnetic resonance (EPR) tests. It indicates that the <i>e</i><sub>g</sub> orbital occupation of Fe<sup>2+</sup> can be finely regulated, thus optimizing the bond strength between the oxidation and reduction processes. Furthermore, from UV−vis DRS and four-point probe conductivity measurements, it can be seen that, after adjusting the electron spin states, the band gap of the material has decreased from 1.01 to 0.80 eV, and the electronic conductivity has increased from 8.5 to 24.4 µS cm<sup>−1</sup>, thereby leading to competitive electrochemical performance. The as-optimized Na<sub>4</sub>Fe<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>P<sub>2</sub>O<sub>7</sub> displays both excellent rate performance (121.0 and 104.9 mAh g<sup>−1</sup> at 0.1 C and 5 C, respectively) and outstanding cycling stability (88.5% capacity retention after 1000 cycles at 1 C). The results indicate that this low-cost Mn/F dual-doping Na<sub>4</sub>Fe<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>P<sub>2</sub>O<sub>7</sub> cathode can be a competitive candidate material for sodium-ion batteries.</p>","PeriodicalId":112,"journal":{"name":"Advanced Functional Materials","volume":null,"pages":null},"PeriodicalIF":18.5000,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Advanced Functional Materials","FirstCategoryId":"88","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/adfm.202309701","RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
A NASICON-type Mn/F dual-doping Na4Fe3(PO4)2P2O7 cathode material is successfully synthesized via a spray drying method. A medium-spin of Fe is measured by DFT calculation, X-ray absorption near edge structure (XANES), temperature-dependent magnetization susceptibility (M−T) measurement, and electron paramagnetic resonance (EPR) tests. It indicates that the eg orbital occupation of Fe2+ can be finely regulated, thus optimizing the bond strength between the oxidation and reduction processes. Furthermore, from UV−vis DRS and four-point probe conductivity measurements, it can be seen that, after adjusting the electron spin states, the band gap of the material has decreased from 1.01 to 0.80 eV, and the electronic conductivity has increased from 8.5 to 24.4 µS cm−1, thereby leading to competitive electrochemical performance. The as-optimized Na4Fe3(PO4)2P2O7 displays both excellent rate performance (121.0 and 104.9 mAh g−1 at 0.1 C and 5 C, respectively) and outstanding cycling stability (88.5% capacity retention after 1000 cycles at 1 C). The results indicate that this low-cost Mn/F dual-doping Na4Fe3(PO4)2P2O7 cathode can be a competitive candidate material for sodium-ion batteries.
期刊介绍:
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