Studying the conversion reaction mechanism of FeS2 in solid-state batteries by operando XRD/PDF/XANES

FeS2 is a promising conversion cathode material for Li/Na batteries, due to the abundant of iron and sulfur in the Earth crust, and unlike S, Li2S or Na2S, FeS2 have a much better electrical conductivity which outperform the other conversion materials. In contrast to liquid electrolyte – based battery, the understanding of reaction mechanism of FeS2 as cathode material in all solid-state Li/Na battery is still in doubt. Therefore, we use a novel operando set-up, which we developed in cooperation with beamline scientists from BM31, to study the phase transformation, microstructure evolution of FeS2, and change of oxidation of Fe during different electrochemical driven condition in solid-state batteries under dynamic and static stack pressure via XRD, EXAFS, XANES, and PDF to provide a new understanding on phase and microstructural evolution as well as mechanical degradation as a function of capacity utilization and applied current.