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Li–Ni–Mn spinels of nominal composition LiNi0.5Mn1.5O4, which are functional materials for electrodes in high‐voltage lithium batteries, are prepared by thermal decomposition of mixed nanocrystalline oxalates obtained by grinding hydrated salts and oxalic acid in the presence of polyethyleneglycol 400. Their structure, microstructure, and texture are established from combined X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction, transmission electron microscopy (TEM), IR spectroscopy, and N2 absorption measurements. The polymer tailors the shape of particles, which adopt a nanorodlike morphology at low temperatures (400 °C). In fact, the nanorods consist of highly distorted oriented nanocrystals connected by a polymer‐based film as inferred from IR and XPS spectra. The electrochemical properties of spinels in this peculiar form are quite poor, mainly as a result of the high microstrain content of their nanocrystals. Raising the temperature up to 800 °C partially destroys the nanorods, which become highly crystalline nanoparticles approximately 80 nm in size. At this temperature, the polymer facilitates crystal growth; this leads to highly crystalline polyhedral nanoparticles as revealed from TEM images and microstrain data. Following functionalization as a cathode in lithium cells, this material exhibits a very good rate capability, coulombic efficiency, and capacity retention even upon cycling at voltages as high as 5 V. Moreover, it withstands fast‐charge–slow‐discharge processes, which is an important cycle‐life‐related property for commercial batteries.

Nanometric mixed iron-titanium oxides were prepared by mechanical milling with a view to determining their ability to act as anodic materials in lithium cells. At a TiO 2 /Fe 2 O 3 mole ratio of 0.4, a solid-state reaction occurs that leads to the formation of Fe 5 TiO 8 , which possesses a spinel-like structure; at lower ratios, however, the structure retains the hematite framework. Li/g-Fe 2 O 3 cells exhibit poor electrochemical reversibility; by contrast, Ti-containing electrodes possess improved cycling properties. Changes in the electrodes upon cycling were examined by X-ray photoelectron spectroscopy ͑XPS͒. XPS data confirm the participation of electrolyte in the electrochemical reaction and the different type of electrochemical reversibility exhibited by samples. Both processes were influenced by the presence of titanium. Titanium dioxide, in the presence of iron oxides, seems to be inactive to the electrochemical process. Based on the step potential electrochemical spectroscopy ͑SPES͒ curves and photoelectron spectra obtained, the presence of Ti increases the reversibility of the redox reactions undergone by the electrolyte during discharge/charge processes. The increased active-material/electrolyte/inactive-material interaction which is reported here offers new perspectives for the use of well-known transition oxides as anode materials in Li-ion batteries.

Graphene nanosheets (GNS) were prepared from graphitic oxide (GO) in two different ways: (a) thermal exfoliation at different temperatures; and (b) wet chemistry, using aqueous N(2)H(4) and KBH(4) as reducing agents. Irrespective of the synthetic method used, the materials exhibited a high irreversible capacity and strong polarization in their charge curves, when used in a Li-ion battery. The GNS synthesized with N(2)H(4) exhibited the best performance. Thus, at 149 mA g(-1) the average specific capacity delivered was ca. 600 mA h g(-1) after 100 cycles. On the other hand, the worst performance, irrespective of rate, was that of GNS synthesized with KBH(4) and the thermal GNS obtained at 800 °C. The physical and chemical analyses allowed various parameters to be derived for correlation with the electrochemical properties. Unfortunately, no clear-cut correlation was apparent. A comparison with reported data revealed that no correlation appears to exist with physical and chemical properties that allows a simple strategy for tailoring an effective graphene anode to be designed.

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