Manganites of transition and/or post-transition metals, AMn 2 O 4 (where A was Co, Ni or Zn), were synthesized by a simple and easily scalable co-precipitation route and were evaluated as anode materials for Li-ion batteries. The obtained powders were characterized by SEM, TEM, and XRD techniques. Battery cycling showed that ZnMn 2 O 4 exhibited the best performance (discharge capacity, cycling, and rate capability) compared to the two other manganites and their corresponding simple oxides. Further studies on the effect of different sintering temperatures (from 400 to 1000 C) on particle size were performed, and it is found that the size of the particles had a significant effect on the performance of the batteries. The optimum particle size for ZnMn 2 O 4 is found to be 75-150 nm. In addition, the use of water-soluble and environmentally friendly binders, such as lithium and sodium salts of carboxymethlycellulose, greatly improved the performance of the batteries compared to the conventional binder, PVDF. Finally, ZnMn 2 O 4 powder sintered at 800 C (<150 nm) and the use of the in-house synthesized lithium salt of carboxymethlycellulose (LiCMC) binder gave the best battery performance: a capacity of 690 mA h g À1 (3450 mA h mL À1 ) at C/10, along with good rate capability and excellent capacity retention (88%).

/npsi/ctrl?action=rtdoc&an=9064983&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=9064983&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1016/j.ssi. 2006.05.005 Solid State Ionics, 177, 13-14, pp. 1205Ionics, 177, 13-14, pp. -1210Ionics, 177, 13-14, pp. , 2006 A comparative study of the Ruddlesden-Popper series, Lan+1NinO3n+1 (n=1, 2 and 3), for solid-oxide fuel-cell cathode applications Amow, Gisele; Davidson, Isobel; Skinner, S. J.A comparative study of the Ruddlesden-Popper series, La n+1 Ni n O 3n+1 (n = 1, 2 and 3), for solid-oxide fuel-cell cathode applications AbstractA comparative investigation of the much-studied La 2 NiO 4+δ (n = 1) phase and the higher-order Ruddlesden-Popper phases, La n+1 Ni n O 3n+1 (n = 2 and 3), has been undertaken to determine their suitability as cathodes for intermediate-temperature solid-oxide fuel cells. As n is increased, a structural phase transition is observed from tetragonal I4/mmm in the hyperstoichiometric La 2 NiO 4.15 (n = 1) to orthorhombic Fmmm in the oxygen-deficient phases, La 3 Ni 2 O 6.95 (n = 2) and La 4 Ni 3 O 9.78 (n = 3). High temperature d.c. electrical conductivity measurements reveal a dramatic increase in overall values from n = 1, 2 to 3 with metallic behavior observed for La 4

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We have investigated the electronic and atomic structure of a manganese-chromium-based layered oxide material Li͓Li 0.2 Cr 0.4 Mn 0.4 ͔O 2 during electrochemical cycling using in situ X-ray absorption spectroscopy. Our results indicate that charge compensation in the cathode material is achieved by the oxidation/reduction of octahedral Cr͑III͒ ions to tetrahedral Cr͑VI͒ ions during delithiation/lithiation. Manganese ions are present predominantly in the Mn͑IV͒ oxidation state and do not appear to actively participate in the charge compensation process. To accommodate the large changes in coordination symmetry of the Cr͑III͒ and Cr͑VI͒ ions, the chromium ions have to move between the regular octahedral sites in the R3 m-like lattice to interstitial tetrahedral sites during the charge/discharge process. The highly reversible ͑at least after the first charge͒ three-electron oxidation/ reductions and the easy mobility of the chromium between octahedral and tetrahedral sites are very unusual and interesting. Equally interesting is the fact that chromium is the active metal undergoing oxidation/reduction rather than manganese. Our results also suggest that in the local scale manganese and chromium ions are not evenly distributed in the as-prepared material, but are present in separate domains of Mn and Cr-rich regions.

Electrochemical, X-ray diffraction, and K and L edge X-ray absorption data are reported for the layered cathode material Li 1.2 Mn 0.4 Cr 0.4 O 2 . The structural data show that this material can be understood as a solid solution of the layered phases Li 2 MnO 3 and LiCrO 2 , comprising tretravalent Mn and trivalent Cr, with approximately 0.2 lithium incorporated in the transition metal layers. According to the analysis of the K edge extended X-ray absorption fine structure, lithium ions in the transition metal layers are clustered around Mn ions. L edge X-ray absorption near edge spectra show that in the first charge-discharge cycle chromium is the electrochemically active species, cycling between Cr 3ϩ and Cr 6ϩ . Manganese remains as Mn 4ϩ throughout charge and discharge.Layered lithium manganese oxides are of interest as cathodes for rechargeable lithium batteries due to the safety, low cost, and low toxicity of manganese-based materials. However, basic problems such as the collapse of the layer structure toward the spinel structure have not yet been solved. This collapse usually leads to poor rate performance and to evolution of a two-plateau voltage profile, both of which are undesirable for practical applications. 1 Recently the development of a novel layered oxide cathode material, Li 1.2 Cr 0.4 Mn 0.4 O 2 , was reported, showing high capacity and good cycling stability in lithium-ion cells. 2 The material belongs to the solid solution series Li 2ϩx Cr y Mn 2Ϫy O 4ϩ␦ first reported by Davidson et al.,3,4 corresponding to the formulation Li 3 CrMnO 5 using the notation given by Davidson et al. ͑in the present work we prefer to use the notation Li 1.2 Cr 0.4 Mn 0.4 O 2 because it relates better to the rock salt crystal structure, as discussed below͒. Davidson et al. have evaluated the solid solution range in Li 2ϩx Cr y Mn 2Ϫy O 4ϩ␦ from y ϭ 0.49 to y ϭ 1.46, and found that discharge capacity tends to increase with higher Cr/Mn ratio, up to 230 mAh/g. 3 Although lower Cr/Mn ratios gave lower capacities, high reversible capacities of up to 200 mAh/g were found in examples with a Cr/Mn ratio of around 1.0.The objective of the work reported here is to examine in greater detail the structure and electrochemistry of the Li 1.2 Cr 0.4 Mn 0.4 O 2 material. We are interested in this phase because the composition has shown high capacity and yet contains 50% of its transition metal content as Mn. During the first charge of this material, up to 270 mAh/g ͑corresponding to nearly 1 Li in Li 1.2 Cr 0.4 Mn 0.4 O 2 ͒ can be extracted. This is only possible if either side reactions occur or the average transition metal valence state in the charged cathode is higher than the expected tetravalent state. The work reported here uses a combination of X-ray diffraction, and X-ray absorption at the transition metal K and L edges, to investigate the crystal and electronic structure of Li 1.2 Cr 0.4 Mn 0.4 O 2 , as prepared and during the first charge-discharge cycle. X-ray diffraction ͑XRD͒ gives information about the long range o...