Among all the positive electrode materials explored for Na‐ion batteries, the family of Na3VIII2‐y(VIVO)y(PO4)2F3‐y (NVPFOy) has attracted extensive attention for its high operating voltage and structural stability. In order to promote better performance at high rates, it appears interesting to consider the correlation between NVPFOy’s composition, morphology (size and shape) and electrochemical properties. Here, solvothermal syntheses were considered in order to obtain a series of NVPFOy compounds showing different morphologies (such as nanospheres, flakes, cylindrical aggregates or desert‐roses) by playing on different synthesis parameters like water/ethanol ratio, stoichiometry of the precursors’ mixture, heating rate, and the presence or not of a surfactant. Four compounds presenting different morphology have been fully characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, infrared, NMR and XPS spectroscopies. Their electrochemical properties are studied using electrodes rich in active material in order to better observe the influence of the morphology on the energy storage performance and are compared to those of Na3V2(PO4)2F3 and Na3V2(PO4)2FO2 reference materials obtained by solid‐state synthesis and with shapeless morphology.

Electrodes F 3000 New Spinel Cobalt Oxides, Potential Conductive Additives for the Positive Electrode of Ni-MH Batteries. -Highly conducting cobalt spinel phases close to Co 3 O 4 with defects are synthesized by electro-oxidation of CoO in concentrated alkaline electrolytes at 90°C. The presence of Li in the electrolyte plays an important role in the conductivity of the synthesized phases. In 2.5 M LiOH, H0.60Li0.19Co2.62O4 forms which exhibits cobalt vacancies which are only partially compensated by H + and Li + ions leading to the formation of Co 4+ ions that causes the high electronic conductivity. This phase can be successfully used as conductive additive in the positive electrode of Ni-MH batteries. -(TRONEL, F.; GUERLOU-DEMOURGUES*, L.; MENETRIER, M.; CROGUENNEC, L.; GOUBAULT, L.; BERNARD, P.; DELMAS, C.; Chem. Mater.

The title compound is prepared by solid state reaction of Na2CO3, MnCO3, FeC2O4, and NH4H2PO4 at 900°C, and by the Pechini sol-gel method starting with stoichiometric mixtures of the same educts in aqueous solutions containing citric acid (800°C, 30 min). The samples are characterized by XRD and neutron diffraction, SEM, Moessbauer spectroscopy, and DFT calculations. The compound obtained by the Pechini method has the composition Na0.95Mn1.09Fe2.02(PO4)3. All the prepared samples crystallize in the monoclinic space group C2/c. The three-dimensional skeleton structure exhibits two types of one-dimensional tunnels where the Na + ions are located. The samples prepared by the sol-gel method exhibit much better performances as positive electrodes in lithium cells. The material can intercalate 1.5 Li + ions per formula unit at low rate. -(TRAD, K.; CARLIER*, D.; CROGUENNEC, L.; WATTIAUX, A.; AMARA, M. B.; DELMAS, C.; Chem.