To the electrochemistry of pyrite in Li/solid composite-polymer-electrolyte battery

The purpose of this work is the study of the charge-discharge mechanism in the all-solid-state lithium/composite-polymer-electrolyte/pyrite battery operating at 120 °C. Effects on the charge-discharge mechanism of particle size, type of binder and cathode preparation method of the pyrite-based cathode are addressed. Analysis of the experimental XRD, XPS and electrochemical data suggests that creation of sulfur vacancies in pyrite suppresses a sudden jump of charge voltage, which is associated with slow mass transport of iron(II) cations through the Li₂FeS₂ phase. We believe that our experimental findings show considerable promise of creating sulfur-deficient pyrite structures for cathodes to be used in high-energy-density all-solid-state lithium batteries. The nature and exact composition of a 1.2-1.3 V discharge plateau is still unclear. To clarify the composition of this low-voltage phase synchrotron X-ray absorption measurements were performed on a series of cells cycled more than 100 times. The results will be presented in a forthcoming publication.