Chen, Ruiyong ; Knapp, Michael ; Yavuz, Murat ; Heinzmann, Ralf ; Wang, Di ; Ren, Shuhua ; Trouillet, Vanessa ; Lebedkin, Sergei ; Doyle, Stephen ; Hahn, Horst ; Ehrenberg, Helmut ; Indris, Sylvio (2014)
Reversible Li+Storage in a LiMnTiO4Spinel and Its Structural Transition Mechanisms.
In: The Journal of Physical Chemistry C, 118 (24)
doi: 10.1021/jp501618n
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

In this work, LiMnTiO4 (a structural analogue of classic spinel LiMn2O4) with a disordered cubic spinel structure (Fd (3) over barm) has been synthesized by a low-temperature sol-gel route. The as-obtained LiMnTiO4 exhibits excellent cycling stability in a wide voltage range from 1.5 to 4.8 V with high discharge capacities of 290, 250, and 140 mA h g(-1) at a C/40, C/19, and 1C rate, respectively. Combined long- and short-range structural characterization techniques are used to reveal the correlation between structure and electrochemical behavior. During cycling, the charge/discharge profiles of LiMnTiO4 evolve from initially two well-separated plateaus into sloping regimes. In the early stage of discharge, LiMnTiO4 undergoes phase transitions from an initial spinel phase to mixtures of predominant rock-salt (Fm (3) over barm) and tetragonal (I4(1)/amd) structures along with a decrease in crystallite size from 12 nm to 3 to 4 nm. During further cycling, the spinel/rock-salt phase transition was found to be reversible with the cubic framework remaining intact. The presence of the tetragonal phase after the first discharge suggests that the Mn3+ Jahn-Teller distortion is partially involved during lithiation from Li1-yMn3+yTiO4 to Li1+xMn3-xTiO4 and the fraction of such a tetragonal phase remains at about 30-40% during subsequent cycling.

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