{"title":"Elucidation of the Reaction Mechanisms in Antifluorite-Type Li5+xFe1-xCoxO4 Positive Electrodes for Li-Ion Batteries","authors":"Rasmus Vester Thøgersen, Halvor Høen Hval, Helmer Fjellvåg","doi":"10.1002/batt.202400348","DOIUrl":null,"url":null,"abstract":"<p>The Li-rich antifluorite-type oxides Li<sub>5</sub>FeO<sub>4</sub>, Li<sub>5.5</sub>Fe<sub>0.5</sub>Co<sub>0.5</sub>O<sub>4</sub> and Li<sub>6</sub>CoO<sub>4</sub> have been investigated as positive electrode materials for Li-ion batteries in a combined <i>operando</i> XANES and XRD experiment. All materials show a similar two-step behaviour upon initial charge (termed Stage I and Stage II), and reversibility of subsequent cycling depends upon whether the initial charge cycle is terminated following Stage I or allowed to proceed through Stage II. By tracking the energetic evolution of the XANES pre-edge feature present in both Fe and Co K-edge spectra, as well as the evolution of X-ray diffractograms during charge and discharge, we correlate the changes in chemical coordination and oxidation states in both species and the structural changes to the electrochemical potential profile, and infer the role of anionic redox processes.</p>","PeriodicalId":132,"journal":{"name":"Batteries & Supercaps","volume":"7 9","pages":""},"PeriodicalIF":5.1000,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/batt.202400348","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Batteries & Supercaps","FirstCategoryId":"88","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/batt.202400348","RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ELECTROCHEMISTRY","Score":null,"Total":0}
引用次数: 0
Abstract
The Li-rich antifluorite-type oxides Li5FeO4, Li5.5Fe0.5Co0.5O4 and Li6CoO4 have been investigated as positive electrode materials for Li-ion batteries in a combined operando XANES and XRD experiment. All materials show a similar two-step behaviour upon initial charge (termed Stage I and Stage II), and reversibility of subsequent cycling depends upon whether the initial charge cycle is terminated following Stage I or allowed to proceed through Stage II. By tracking the energetic evolution of the XANES pre-edge feature present in both Fe and Co K-edge spectra, as well as the evolution of X-ray diffractograms during charge and discharge, we correlate the changes in chemical coordination and oxidation states in both species and the structural changes to the electrochemical potential profile, and infer the role of anionic redox processes.
通过 XANES 和 XRD 联合操作实验，研究了作为锂离子电池正极材料的富锂反萤石型氧化物 Li5FeO4、Li5.5Fe0.5Co0.5O4 和 Li6CoO4。所有材料在初始充电时都表现出类似的两步行为（称为阶段 I 和阶段 II），后续循环的可逆性取决于初始充电循环是在阶段 I 后终止还是在阶段 II 后继续进行。通过跟踪铁和钴 K 边光谱中出现的 XANES 前沿特征的能量演变，以及充放电过程中 X 射线衍射图的演变，我们将两种材料中化学配位和氧化态的变化以及结构变化与电化学势曲线联系起来，并推断出阴离子氧化还原过程的作用。
期刊介绍：
Electrochemical energy storage devices play a transformative role in our societies. They have allowed the emergence of portable electronics devices, have triggered the resurgence of electric transportation and constitute key components in smart power grids. Batteries & Supercaps publishes international high-impact experimental and theoretical research on the fundamentals and applications of electrochemical energy storage. We support the scientific community to advance energy efficiency and sustainability.
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