Entropy of the intercalation compound LixMo6Se8 from calorimetry of electrochemical cells

Abstract

We describe the first measurements of changes in the entropy s of intercalation compounds from calorimetry of electrochemical cells. A lattice-gas model of intercalation accurately describes the variation of (∂s/∂x${)}_T$ with x in ${\mathrm{Li}}_{\mathrm{x}}$ ${\mathrm{Mo}}_6$ ${\mathrm{Se}}_8$ at fixed temperature T with no adjustable parameters. This agreement implies that the Li atoms in ${\mathrm{Li}}_{\mathrm{x}}$ ${\mathrm{Mo}}_6$ ${\mathrm{Se}}_8$ for x<1 are randomly distributed over a single type of site.