ORIGINAL PAPER Local structure and electrochemistry of LiNi y Mn y Co 1 - 2y O 2 electrode materials for Li-ion batteries K. Ben Kamel & N. Amdouni & A. Abdel-Ghany & K. Zaghib & A. Mauger & F. Gendron & C.M. Julien Received: 1 September 2007 / Accepted: 2 October 2007 / Published online: 30 November 2007 # Springer-Verlag 2007 Abstract A series of LiNi x Mn y Co z O 2 (x = y , z =1 - 2y) oxides have been synthesized by “chimie douce” and investigated as positive electrodes in rechargeable lithium batteries. Layered LiNi y Mn y Co 1 - 2y O 2 materials with high homogeneity and crystallinity were synthesized using the wet-chemical method assisted by carboxylic acid as the polymeric agent. The long range and local structural properties are investigated with experiments including X- ray diffraction, Fourier transform infrared spectroscopy, and electron paramagnetic resonance spectroscopy. The evolu- tion of the structure is discussed as a function of the cobalt content that confers layer-like behavior on the framework. Electrochemical performance of LiNi y Mn y Co 1 - 2y O 2 oxides is tested in cells using nonaqueous 1 M LiPF 6 dissolved in ethylene carbonate–diethyl carbonate. Charge–discharge profiles are investigated as a function of the rate capability and the voltage window. A relation is found between the gravimetric capacity and the cation disorder of the positive electrode as indicated by structural analysis. Fast lithium extraction attributed to the larger interslab space has been observed in the cobalt-rich oxides. Keywords Transition-metal oxides . Layered structure . Intercalation compounds . Li-ion batteries Introduction The design of a new positive electrode for rechargeable Li-ion batteries with high capacity at higher working potential than 3 V is of current interest [1–7]. In this respect, the layered compounds LiNi y Mn y Co 1 - 2y O 2 are promising candidates for lithium battery cathodes. The materials are situated in the ternary LiCoO 2 –LiNiO 2 –LiMnO 2 system, and various compositions in the diagram were examined. However, as the capacity retention appeared to be depen- dent on the cationic distribution in lithium transition metal oxides, this effect has been recognized as a key parameter for understanding the electrochemical behavior of cathode materials. Spectroscopic methods can be used to probe the structural properties at the local scale and then investigate the local cationic distribution in these complex oxide systems [8, 9]. The structure of layered LiNi y Mn y Co 1 - 2y O 2 compounds consists of a cubic close-packed (ccp) arrangement of the oxide ions with the stacking sequence of ABCABC along the c-axis. The transition metal ions in the structure occupy alternating layers in the octahedral sites. Accordingly, these Ionics (2008) 14:89–97 DOI 10.1007/s11581-007-0167-y DO00167; No of Pages Paper presented at the 11th Euro-Conference on Science and Technology of Ionics, Batz-sur-Mer, France, 9–15 Sept. 2007. K. B. Kamel : N. Amdouni Département de Chimie, Faculté des Sciences, Université Tunis-El Manar, 1060 Tunis, Tunisia A. Abdel-Ghany : F. Gendron : C. Julien (*) Institut des Nanosciences de Paris, UMR7588, Université Pierre et Marie Curie, Campus Boucicaut, 140 rue de Lourmel, 75015 Paris, France e-mail: Christian.Julien@insp.jussieu.fr K. Zaghib Institut de Recherche d’Hydro-Québec (IREQ), 1800 boul. Lionel-Boulet, Varennes, QC J3X 1S1, Canada A. Mauger Institut de Minéralogie et Physique de la Matière Condensée, UMR7590, Université Pierre et Marie Curie, 140 rue de Lourmel, 75015 Paris, France