An in situ X-ray absorption spectroscopy study of InSb electrodes in lithium batteries

We present a detailed in situ extended X-ray absorption fine-structure spectroscopy (EXAFS) study of structural and compositional changes in InSb intermetallic electrodes under electrochemical cycling conditions in a lithium battery. Analysis of the EXAFS data shows that Li is inserted into and In is extruded from the zinc-blende-type InSb network during the first discharge from 1.5 to 0.5 V. yielding changing Lix+vIn1-vSb compositions (0 < x <less than or equal to> 2, 0 < y <less than or equal to> 1), with a lattice parameter that varies between that of InSb (a = 6.478 Angstrom) and Li3Sb (a = 6.572 Angstrom). The structural features of tetragonal metallic In and lithiated (i.e., In depleted) InSb are evident. The fully recharged electrode, at 1.2 V, has a zinc-blende framework closely resembling InSb. However, 40% of the In remains permanently outside the face-centered-cubic Sb lattice, explaining a loss in capacity after the first discharge. After the second discharge, at 0.51 V, Li has replaced about 80% of the indium in the InSb lattice, while the LixInxSb volume has expanded less than 4% compared to the initial electrode. Finally, as the cell is discharged below 0.51 V, Li reacts with the In metal, forming LiIn. Our results indicate that intermetallic electrodes are promising alternative negative electrodes for Li batteries. (C) 2001 Published by Elsevier Science B.V.