@article{27838,
  author = {Kathryn A Striebel and Aline Rougier and Craig R Horne and Ronald P Reade and Elton J Cairns},
  title = {Electrochemical Studies of Substituted Spinel Thin Films},
  abstract = {<p>Thin lithium manganese oxide spinel films, prepared with pulsed laser deposition have been used as a model system for the study of oxide electrochemical properties and performance degradation mechanisms in the absence of carbon or binder materials. Films (0.3 mm) of Li<sub>x</sub>Mn<sub>2-y</sub>Me<sub>y</sub>O<sub>4</sub>, where Me = Ni, Co and y = 0, 0.1, 0.25, were crystalline as-prepared. The cyclic voltammetric response as a function of oxide composition was measured in liquid electrolyte over the range of 2 to 5.8 V <em>vs.</em> Li/Li<sup>+</sup>. Quantitative analysis of the two 4 V peaks, for x &gt; 0.5 and x &lt; 0.5, correlated well with predicted film stoichiometry. The capacity of the 4.6 V redox peaks in the Ni-substituted films were consistent with the oxidation of Ni<sup>2+</sup> to Ni<sup>4+</sup>. No significant capacity was observed in LiMn<sub>2</sub>O<sub>4</sub> above 4.5 V. The shape of the voltammetric peaks in the 3 V region suggested that intercalation kinetics are slowed by the Jahn-Teller distortion, while all compositions in the 4 V region showed reversible behavior, except for the LiNi<sub>0.25</sub>Mn<sub>1.75</sub>O<sub>4</sub> film which showed lower electronic conductivity. The LiMn<sub>1.90</sub>Ni<sub>0.10</sub>O<sub>4</sub> films showed no loss in discharge capacity after being charged up to 5.7 V <em>vs.</em> Li/Li<sup>+</sup> with window-opening cyclic voltammetry. LiMn<sub>2</sub>O<sub>4</sub> and LiMn<sub>1.75</sub>Co<sub>0.25</sub>O<sub>4</sub> films were stable to 5.6 and 5.4 V <em>vs.</em> Li/Li<sup>+</sup>, respectively. Explanations for the superior stability of the films relative to powder electrodes are examined.</p>},
  year = {1999},
  journal = {Journal of The Electrochemical Society},
  volume = {146},
  pages = {4339-4347},
  issn = {00134651},
  doi = {10.1149/1.1392640 },
}