Structural and electrochemical properties of new nanospherical manganese oxides for lithium batteries
Por:
Strobel P., Thiéry F., Darie C., Proux O., Ibarra-Palos A., Bacia M., Soupart J.B.
Publicada:
1 ene 2005
Resumen:
The products of decomposition of manganese carbonate with and without doping by copper or cobalt, at temperatures <500 °C in air were studied. Doped systems with 20 atom% Cu or Co give new nanometric manganese oxides agglomerated in submicronic spheres at 370 °C. Transmission electron microscopy (TEM) shows that these X-ray amorphous compounds are nanocrystalline with grain size in the 10 nm range and a spinel substructure. The electrochemical behaviour of these materials in lithium cells was studied. Whereas non-doped manganese oxide exhibits poor intercalation capabilities, the freshly co-precipitated Cu or Co doped materials can be cycled successfully around 3 V vs. Li/Li +. Step-potential electrochemical spectroscopy shows that the initial discharge gives rise to a two-phase transition and is followed by stable, reversible, single-phase cycling. Best results are obtained on a cobalt-doped manganese oxide (Co : Mn =1:5), which can sustain more than 100 charge-discharge cycles with a 175 mA h g -1 capacity in the 1.8-4.2 V range. XAS spectra were measured on pristine and electrochemically discharged materials, showing that (1) in the cobalt-doped material, cobalt is divalent and manganese is the only redox-active species, (2) the variations in local structure around Mn on discharge are much smaller than in long-range ordered compounds such as Li-Mn-O spinels. © The Royal Society of Chemistry 2005.
Filiaciones:
Strobel P.:
Centre National de la Recherche Scientifique, Laboratoire de Cristallographie, BP166, 38042 Grenoble Cedex 9, France
Thiéry F.:
Centre National de la Recherche Scientifique, Laboratoire de Cristallographie, BP166, 38042 Grenoble Cedex 9, France
Darie C.:
Centre National de la Recherche Scientifique, Laboratoire de Cristallographie, BP166, 38042 Grenoble Cedex 9, France
Proux O.:
Laboratoire de Géophysique Interne et Tectonophysique, CNRS, Université Joseph Fourier, 38400 Saint-Martin-d'Hères, France
Ibarra-Palos A.:
Centre National de la Recherche Scientifique, Laboratoire de Cristallographie, BP166, 38042 Grenoble Cedex 9, France
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Ciudad Universitaria, A.P. 70-360, Coyoacan 04510, México, D.F., Mexico
Bacia M.:
Centre National de la Recherche Scientifique, Laboratoire de Cristallographie, BP166, 38042 Grenoble Cedex 9, France
Soupart J.B.:
Erachem-Comilog, B-7333 Tertre, Belgium
|