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Lithium manganese oxide is regarded as a capable cathode material for lithium-ion batteries, but it suffers from relative low conductivity, manganese dissolution in electrolyte and structural distortion from cubic to tetragonal during elevated temperature tests. This review covers a comprehensive study about the main directions taken into consideration to supress the drawbacks of lithium manganese oxide: structure doping and surface modification by coating. Regarding the doping of LiMn2O4, several perspectives are studied, which include doping with single or multiple cations, only anions and combined doping with cations and anions. Surface modification approach consists in coating with different materials like carbonaceous compounds, oxides, phosphates and solid electrolyte solutions. The modified lithium manganese oxide performs better than pristine samples, showing improved cyclability, better behaviour at high discharge c-rates and elevated temperate and improves lithium ions diffusion coefficient.

Abstract:The disposal of LiFePO 4 (LFP) cathode material through oxidation in an air atmosphere is explained by its high chemical activity and high surface area (especially for nanoparticles). In this article, new methods for the determination of the degree of iron oxidation in LFP (oxidation degree) are taken into consideration, specifically those which do not require complicated hardware support. The proposed methods are based on electrochemical oxidation (coulometric method) and chemical oxidation (chemical oxidation in alkaline and acidic solutions). As an arbitration method for analyzing the iron state, the method of Mössbauer spectroscopy (being the most proven and reliable method) was chosen. With respect to the proposed methods for determination of the oxidation degree, the most reliable and quick approach is the titrimetric method (oxidation in an acidic medium), which is in good correlation with Mossbauer spectroscopy. The coulometric method is also able to determine the material oxidation degree (with some approximation), but it requires a number of conditions in order to eliminate errors.

In the present paper, nanosized La0.9Sr0.1MnO3 particles were synthesized via a facile modified sol-gel route using two cheap and environmentally friendly organic chemicals, namely sucrose and pectin. The obtained powders were characterized by thermo gravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and magnetic measurements. The optimal temperature for obtaining nanosized particles was determined as 1000�C and 1h dwell time was enough to obtain crystalline nanoparticles. Magnetic properties of samples calcined with different calcination period were analyzed and both samples shown a transition temperature around 274 K.

ABSTRACT. This paper focuses on the synthesis and analysis of some spinelstructured, ceramic pigment nanopowders (Mg(1-x)NixAl2O4) using a modified sol -gel method. This study emphasizes the influence of the Ni/Mg ratio and that of the thermal treatment on the properties of the obtained powders. The behavior of the dried gels during calcination was studied by differential thermal analysis. The formation of the spinel structure after calcination was analyzed using x-ray diffraction. The colour of the powders was characterized by UV -VIS spectroscopy, determining the absorption spectra. In addition, the trichromatic coordinates were determined, and the corresponding pigment positions were fixed on the chromaticity diagram.