Neutron diffraction and electrochemical studies on LiIrSn4

Large quantities of single phase, polycrystalline LiIrSn4 have been synthesised from the elements by melting in sealed tantalum tubes and subsequent annealing. LiIrSn4 crystallises with an ordered version of the PdGa5 structure: I4/mcm  , a=655.62(8)a=655.62(8), c=1128.6(2)pm. The lithium atoms were clearly localised from a neutron powder diffraction study: RP=0.147RP=0.147 and RF=0.058RF=0.058. Time-dependent electrochemical polarisation techniques, i.e. coulometric titration, chronopotentiometry, chronoamperometry and cyclic voltammetry were used to study the kinetics of lithium ion diffusion in this stannide. The range of homogeneity (Li1+ΔδIrSn4, −0.091⩽δ⩽+0.012) without any structural change in the host structure and the chemical diffusion coefficient (∼10−7–10−9 cm2/s) point out that LiIrSn4 is a first example of a large class of intermetallic compounds with lithium and electron mobility. Optimised materials from these ternary lithium alloys may be potential electrode material for rechargeable lithium batteries.

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