Structural peculiarities and electrochemical properties of R₅M₃ (R = La, Gd; M = Ge, Sn) doped by lithium

Chem. Met. Alloys 7 (2014) 106-111

https://doi.org/10.30970/cma7.0282

Andrij STETSKIV, Vasyl KORDAN, Ivan TARASIUK, Oksana ZELINSKA, Volodymyr PAVLYUK

Ternary phases R₅Li_xM₃ were prepared in two ways, by melting and by electrochemical lithiation of the binary compounds R₅M₃. They crystallize in the hexagonal Hf₅CuSn₃ structure type, an ordered superstructure of the Mn₅Si₃ type. Metallic type of bonding was suggested by the analysis of the interatomic distances and confirmed by electronic structure calculations. Electrochemical lithiation reactions of electrodes made of R₅M₃ alloys were studied in an organic electrolyte containing LiPF₆ salt, using the conventional charge-discharge technique, and the reaction products were analyzed by X-ray powder diffraction. The partially lithiated phase, R₅Li_xM₃ (where x < 0.4), appears to be a solid solution of Li in the initial structure of the binary compounds R₅M₃.

Projection of the unit cell of Gd₅Li_0.4Sn₃ and coordination polyhedra of the atoms.

Keywords

Intermetallic compound / Crystal structure / Rare-earth elements / Lithium / Electrochemistry