Influence of Iron on the Structural Evolution of LiNi0.4Fe0.2Mn1.4O4 during Electrochemical Cycling Investigated by in situ Powder Diffraction and Spectroscopic Methods. Issue 15 (5th November 2014)

• Record Type: Journal Article
• Authors: Yavuz, Murat; Kiziltas‐Yavuz, Nilüfer; Bhaskar, Aiswarya; Scheuermann, Marco; Indris, Sylvio; Fauth, Francois; Knapp, Michael; Ehrenberg, Helmut
• Is Part Of: Zeitschrift für anorganische und allgemeine Chemie. Volume 640:Issue 15(2014)
• Page Start: 3118
• Page End: 3126
• Publication Date: 2014-11-05
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry -- Periodicals; 540
• DOI: 10.1002/zaac.201400247
• Languages: English
• ISSNs: 0044-2313

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p> The cathode materials LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> and LiNi<sub>0.4</sub>Fe<sub>0.2</sub>Mn<sub>1.4</sub>O<sub>4</sub> were synthesized using a citric acid‐assisted sol‐gel method with a final calcination temperature of 1000 °C. An impurity phase exists in LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> powders, which can be eliminated by substituting some of the Ni<sup>2+</sup> and Mn<sup>4+</sup> ions with Fe<sup>3+</sup>. The substitution of Fe into the spinel structure was confirmed by NMR and Mössbauer spectroscopy. The initial capacity of LiNi<sub>0.4</sub>Fe<sub>0.2</sub>Mn<sub>1.4</sub>O<sub>4</sub> powder synthesized at 1000 °C (LNFMO) is slightly higher than that of LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> powder synthesized at 1000 °C (LNMO). Additionally, its capacity retention of 92 % at room temperature after 300 cycles at C/2 charging‐discharging rate between 3.5–5.0 V is higher than that of the Fe‐free sample (79.5 %) under same conditions which could arise from the difference in their cycling mechanisms. In order to understand the structural evolution of these materials during electrochemical cycling, <italic>in situ</italic> studies under real operating conditions were performed. Measurements of initial powders in capillaries and <italic>in situ</italic> experiments during the first galvanostatic cycle were carried out by high resolution powder diffraction using synchrotron radiation.</p> </abstract>