Structural and mechanistic features of intermetallic materials for lithium batteries

An anode system based on intermetallic phases with a zinc-blende-type structure (InSb, GaSb and AlSb) has been studied for lithium-ion batteries. The compound, InSb, in particular, cycles well between 1.2 and 0.5 V. After an initial “conditioning” cycle, a mechanism involving lithium insertion into an open framework structure followed by indium extrusion in the potential range 1.2–0.7 V, appears to dominate; between 0.7 and 0.5 V, a more complex mechanism occurs involving indium extrusion from a stable fcc Sb anion array and subsequent lithiation of the extruded indium. In situ X-ray diffraction and extended X-ray analysis fine structure (EXAFS) data were obtained over the voltage window 1.2–0.5 V, where a rechargeable capacity of 300 mAh/g is achievable. The results indicate that after the “conditioning” reaction a LiyIn1−ySb zinc-blende framework, in which Li atoms partially substitute for In, is responsible for the good cycling behavior of the cells. Isostructural AlSb and GaSb electrodes provide inferior electrochemical capacities.