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| 1 | Probing thermally-induced structural evolution during the synthesis of layered Li-, Na-, or K-containing 3d transition-metal oxides显示文摘Layered alkali-containing 3d transition-metal oxides are of the utmost importance in the use of electrode materials for advanced energy storage applications such as Li-,Na-,or K-ion batteries.A significant challenge in the field of materials chemistry is understanding the dynamics of the chemical reactions between alkali-free precursors and alkali species during the synthesis of these compounds.In this study,in situ high-resolution synchrotron-based X-ray diffraction was applied to reveal the Li/Na/K-ion insertion-induced structural transformation mechanism during high-temperature solid-state reaction.The in situ diffraction results demonstrate that the chemical reaction pathway strongly depends on the alkali-free precursor type,which is a structural matrix enabling phase transi-tions.Quantitative phase analysis identifies for the first time the decomposition of lithium sources as the most critical factor for the formation of metastable intermediates or impurities during the entire process of Li-rich layered Li[Li_(0.2)Ni_(0.2)Mn_(0.6)]O_(2) formation.Since the alkali ions have different ionic radii,Na/K ions tend to be located on prismatic sites in the defective layered structure(Na_(2/3-x)[Ni_(0.25)Mn_(0.75)]O_(2) or K_(2/3-x)[Ni_(0.25)Mn_(0.75)]O_(2))during calcination,whereas the Li ions prefer to be localized on the tetrahedral and/or octahedral sites,forming O-type structures. | Weibo Hua Xiaoxia Yang Nicola PMCasati Laijun Liu Suning Wang Volodymyr Baran Michael Knapp Helmut Ehrenberg Sylvio Indris | 2022 | eScience2022，2，2： | 2 |
| 2 | Lithium dendrite and solid electrolyte interphase investigation using OsO 4显示文摘 | Martin Zier Frieder Scheiba Steffen Oswald Jürgen Thomas Dietrich Goers Torsten Scherer Markus Klose Helmut Ehrenberg Jürgen Eckert | 2014 | Journal of Power Sources2014，，： | 1 |
| 3 | Precursorbased synthesis and electrochemical performance of LiMnPO4显示文摘 | Natalia N Bramnik Helmut Ehrenberg | 2008 | Journal of Alloys and Compounds2008，464，12： | 1 |
| 4 | Study of the effect of different synthesis routes on Li extraction–insertion from LiCoPO 4显示文摘 | Natalia N. Bramnik Kirill G. Bramnik Carsten Baehtz Helmut Ehrenberg | 2005 | Journal of Power Sources2005，，1： | 1 |
| 5 | Precursor-based syn- thesis and electrochemical performance of LiMnPO4 显示文摘 | Natalia N Bramnik Helmut Ehrenberg | 2008 | J Alloys Compd2008，464，12： | 1 |
| 6 | In situ synchrotron diffraction study of charge–discharge mechanism of sol–gel synthesized Li M 0.5 Mn 1.5 O 4 ( M显示文摘 | Aiswarya Bhaskar Natalia N. Bramnik Dmytro M. Trots Hartmut Fuess Helmut Ehrenberg | 2012 | Journal of Power Sources2012，，： | 1 |
| 7 | In operando study of orthorhombic V_(2)O_(5) as positive electrode materials for K-ion batteries显示文摘Herein, the electrochemical performance and the mechanism of potassium insertion/deinsertion in orthorhombic V_(2)O_(5) nanoparticles are studied. The V2O5 electrode displays an initial potassiation/depotassiation capacity of 200 mAh g^(−1)/217 mAh g^(−1) in the voltage range 1.5–4.0 V vs. K^(+)/K at C/12 rate, suggesting fast kinetics for potassium insertion/deinsertion. However, the capacity quickly fades during cycling, reaching 54 mAh g^(−1) at the 31st cycle. Afterwards, the capacity slowly increases up to 80 mAh g^(−1) at the 200th cycle. The storage mechanism upon K ions insertion into V2O5 is elucidated. In operando synchrotron diffraction reveals that V_(2)O_(5) first undergoes a solid solution to form K_(0.6)V_(2)O_(5) phase and then, upon further K ions insertion, it reveals coexistence of a solid solution and a two-phase reaction. During K ions deinsertion, the coexistence of solid solution and the two-phase reaction is identified together with an irreversible process. In operando XAS confirms the reduction/oxidation of vanadium during the K insertion/extraction with some irreversible contributions. This is consistent with the results obtained from synchrotron diffraction, ex situ Raman, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Moreover, ex situ XPS confirms the “cathode electrolyte interphase” (CEI) formation on the electrode and the decomposition of CEI film during cycling. | Qiang Fu Angelina Sarapulova Lihua Zhu Georgian Melinte Alexander Missyul Edmund Welter Xianlin Luo Michael Knapp Helmut Ehrenberg Sonia Dsoke | 2021 | Journal of Energy Chemistry2021，30，11： | 0 |
| 8 | Elucidation of the sodiation/desodiation mechanism in Ca_(0.5)Ti_(2)(PO_(4))_(3)/C as promising electrode for sodium batteries: New insights into the phase transitions显示文摘The structure evolution and electrochemical performance of Na SICON-type Ca_(0.5)Ti_(2)(PO_(4))_(3) for sodium batteries are presented.This phosphate was synthesized by a solid-state method,and the obtained particles were coated with carbon using sucrose.This compound crystallizes in the rhombohedral system with space group R-3.The presence of carbon in the Ca_(0.5)Ti_(2)(PO_(4))_(3)/C composite was confirmed by Raman and Thermogravimetric analysis.The electrochemical performance of Ca_(0.5)Ti_(2)(PO_(4))_(3)/C was investigated in the potential window 1.5–3.0 V vs.sodium metal at different scan rates.The compound is able to initially intercalate/deintercalate 1.6/1.15 Na per formula unit,respectively.In operando synchrotron diffraction was done in the potential window 0.02–3.0 V vs.Na|Na+and revealed the occurrence of several reaction regions upon first discharge.Up to 4 Na+ion per formula unit can be inserted during the first discharge.An intensive refinement of the synchrotron X-ray diffraction(SXRD)patterns of discharged Ca_(0.5)Ti_(2)(PO_(4))_(3) evidenced the existence of five regions depending on the sodium content while the crystal structures of new phases were elucidated for the first time where sodium insertion occurs in the unusual M3 and M’3 sites of the Na SICON structure. | Abdelhaq Nassiri Noha Sabi Angelina Sarapulova Yingjin Wei Bouchaib Manoun Sylvio Indris Alexandr Missyul Helmut Ehrenberg Ismael Saadoune | 2022 | Journal of Energy Chemistry2022，31，7： | 0 |
| 9 | The effect of electrochemically inactive Ti substituted for Ru in Li_(2)Ru_(1-x)Ti_xO_(3) on structure and electrochemical performance显示文摘The approach of substituting electrochemically active with inactive elements has widely been used to improve the electrochemical performance of Li-rich intercalation cathode materials. This especially is true for Li-rich compounds where almost all of the Li+ions are reversibly(de)intercalated during electrochemical cycling. The beneficial mechanism behind this substitution with electrochemically inactive elements is still not clear yet. Li_(2)RuO_(3) is chosen as basis for a model solid solution system to investigate the effect of electrochemically inactive elements owing to its high specific capacity of more than 300 m Ah g^(-1) and the significant contribution of anion redox mechanism. Herein, Li_(2)Ru_(1-x)Ti_xO_(3) solid solution series are synthesized and the effect of substituting with electrochemical inactive Ti for Ru on structure and electrochemical performance have been comprehensively investigated. The electrochemical performance is significantly improved, especially for Li_(2)Ru_(0.8)Ti_(0.2)O_(3), and the capacity retention after 50 cycles increases from 81% to 90%, as compared to the end member Li_(2)RuO_(3). Results of electrochemical impedance spectroscopy show that Ti substitution reduces the charge transfer impedance, which favors the Li+diffusion across the electrolyte–electrode interface and improves the electronic conductivity. For the first time,nuclear magnetic resonance was utilized to confirm that a small part of Ti ions exchange their position with Li ions in the Li layer. This research provides a better understanding of electrochemical inactive element substitution and strong insights for the functional design of the next generation of Li-rich cathode materials. | Ye Yao Lu Zhang Florian Sigel Bjorn Schwarz Helmut Ehrenberg Gang Chen Fei Du Chunzhong Wang | 2021 | Journal of Energy Chemistry2021，30，9： | 0 |
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