Effects of synthetic conditions on the structural, stability and ion conducting properties of Li0.30(La0.50Ln0.50)0.567TiO3 (Ln= La, Pr, Nd) solid electrolytes for rechargeable lithium batteries

The structure, thermal stability, morphology and ion conductivity of titanium perovskites with the general formula Li3xLn2/3−xTiO3 (Ln = rare earth element; 3x= 0.30) are studied in the context of their possible use as solid electrolyte materials for lithium ion batteries. Materials are prepared by a glycine-nitrate method using different sintering treatments, with a cation-disorder-induced structural transition from tetragonal to cubic symmetry, detected as quenching temperature increases. SEM images show that the average grain size increases with increasing sintering temperature and time. Slightly higher bulk conductivity values have been observed for quenched samples sintered at high temperature. Bulk conductivity decreases with the lanthanide ion size. A slight conductivity enhancement, always limited by grain boundaries, is observed for longer sintering times. TDX measurements of the electrolyte/cathode mixtures also show a good stability of the electrolytes in the temperature range of 30-1100ºC.

Inter- and intramolecular enantioselective carbolithiation reactions

In this review we summarize recent developments in inter- and intramolecular enantioselective carbolithiation reactions carried out in the presence of a chiral ligand for lithium, such as (-)-sparteine, to promote facial selection on a C=C bond. This is an attractive approach for the construction of new carbon-carbon bonds in an asymmetric fashion, with the possibility of introducing further functionalization on the molecule by trapping the reactive organolithium intermediates with electrophiles.

High voltage cathodes for Na-ion batteries: Na3V2O2x(PO4)2F3-2x system

254 p : il, graf. col.

LiMn2-xGexO4 como material catódico para baterías de ión-litio

32 p.

Helmholtz Fermi surface harmonics: an efficient approach for treating anisotropic problems involving Fermi surface integrals

We present a new efficient numerical approach for representing anisotropic physical quantities and/or matrix elements defined on the Fermi surface (FS) of metallic materials. The method introduces a set of numerically calculated generalized orthonormal functions which are the solutions of the Helmholtz equation defined on the FS. Noteworthy, many properties of our proposed basis set are also shared by the FS harmonics introduced by Philip B Allen (1976 Phys. Rev. B 13 1416), proposed to be constructed as polynomials of the cartesian components of the electronic velocity. The main motivation of both approaches is identical, to handle anisotropic problems efficiently. However, in our approach the basis set is defined as the eigenfunctions of a differential operator and several desirable properties are introduced by construction. The method is demonstrated to be very robust in handling problems with any crystal structure or topology of the FS, and the periodicity of the reciprocal space is treated as a boundary condition for our Helmholtz equation. We illustrate the method by analysing the free-electron-like lithium (Li), sodium (Na), copper (Cu), lead (Pb), tungsten (W) and magnesium diboride (MgB2)