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We describe the synthesis, crystal structure and lithium deinsertion-insertion electrochemistry of two new lithium-rich layered oxides, Li3MRuO5 (M = Mn, Fe), related to rock salt based Li2MnO3 and LiCoO2. The Li3MnRuO5 oxide adopts a structure related to Li2MnO3 (C2/m) where Li and (Li0.2Mn0.4Ru0.4) layers alternate along the c-axis, while the Li3FeRuO5 oxide adopts a near-perfect LiCoO2 (R3[combining macron]m) structure where Li and (Li0.2Fe0.4Ru0.4) layers are stacked alternately. Magnetic measurements indicate for Li3MnRuO5 the presence of Mn(3+) and low spin configuration for Ru(4+) where the itinerant electrons occupy a π*-band. The onset of a net maximum in the χ vs. T plot at 9.5 K and the negative value of the Weiss constant (θ) of -31.4 K indicate the presence of antiferromagnetic superexchange interactions according to different pathways. Lithium electrochemistry shows a similar behaviour for both oxides and related to the typical behaviour of Li-rich layered oxides where participation of oxide ions in the electrochemical processes is usually found. A long first charge process with capacities of 240 mA h g(-1) (2.3 Li per f.u.) and 144 mA h g(-1) (1.38 Li per f.u.) is observed for Li3MnRuO5 and Li3FeRuO5, respectively. An initial sloping region (OCV to ca. 4.1 V) is followed by a long plateau (ca. 4.3 V). Further discharge-charge cycling points to partial reversibility (ca. 160 mA h g(-1) and 45 mA h g(-1) for Mn and Fe, respectively). Nevertheless, just after a few cycles, cell failure is observed. X-ray photoelectron spectroscopy (XPS) characterisation of both pristine and electrochemically oxidized Li3MRuO5 reveals that in the Li3MnRuO5 oxide, Mn(3+) and Ru(4+) are partially oxidized to Mn(4+) and Ru(5+) in the sloping region at low voltage, while in the long plateau, O(2-) is also oxidized. Oxygen release likely occurs which may be the cause for failure of cells upon cycling. Interestingly, some other Li-rich layered oxides have been reported to cycle acceptably even with the participation of the O(2-) ligand in the reversible redox processes. In the Li3FeRuO5 oxide, the oxidation process appears to affect only Ru (4+ to 5+ in the sloping region) and O(2-) (plateau) while Fe seems to retain its 3+ state.

The structural features of intercalated Li3AlxTi2-x(PO4)3 compounds, with x = 0 and 0.2, have been deduced by Rietveld analysis of neutron diffraction (ND) patterns recorded between 100 and 500 K. The Li insertion decreases the symmetry from R3̄c to R3̄ in analyzed compounds. In pristine Li1+xAlxTi2-x(PO4)3 samples, Li occupies mainly six-fold M1 sites at ternary axes; but in lithiated Li3AlxTi2-x(PO4)3 samples, Li is located near M2 positions at M3/M3' four-fold coordinated sites. In both cases, Li arrangement minimizes electrostatic Li-Li repulsions. The insertion of lithium resulted in the reduction of Ti(4+) to Ti(3+) that shifts (7)Li, (27)Al and (31)P MAS-NMR resonances towards more positive chemical shifts, improving the resolution of different sites. The detection of twelve components in (7)Li MAS-NMR spectra recorded at room temperature suggests the location of Li(+) ions at three-oxygen faces that define M2 cavities. From (7)Li MAS-NMR spectra, the occupancy of sites and mobility of lithium were investigated in the temperature range 100-500 K. The correlation between structural information, deduced by neutron diffraction, and lithium mobility, deduced by NMR spectroscopy, provides new insights into structural factors that affect lithium mobility in materials with NASICON structure.