Elucidation of the charge-discharge mechanism of lithium/polymer electrolyte/pyrite batteries

The purpose of this work is the elucidation of the charge-discharge mechanism in the all-solid-state lithium/composite polymer electrolyte/pyrite battery operating at 120-135 °C. The main focus is the explanation of the unexpected potential jump at 1.85 V during the charge process. Effects on the charge-discharge mechanism of particle size, pyrolysis, alumina addition and Zn doping of the pyrite-based cathode are addressed. Analysis of the experimental data, as well as the structure of the charge-discharge intermediates, diffusion of lithium and iron cations in the composite cathode, suggests that the sudden charge overpotential is associated with slow mass transport of iron(II) cations through the Li₂FeS₂ phase.