Chemical, structural and electrochemical comparison of natural and synthetic FeS2 pyrite in lithium cells

Enhanced electrochemical performance of FeS2 synthesized by hydrothermal method for lithium ion batteries

“…Figure 3 shows the discharge-charge profiles of a few representative cycles, namely cycle 1, 5, 10, 20, and 30 between 1.2 and 2.6 V at 89 mA g -1 . Both the first discharge curves show an abrupt drop in voltage, followed with a long plateau between 1.4 and 1.45 V. The first discharge plateau is associated with the formation of Fe, Li 2 S, and Li-rich phases depending on the quantity of lithium transfer per FeS 2 [2,34,35]. The subsequent discharge curves differ from the first one, indicating a change in the mechanism of pyrite reduction.…”

Pyrite oxidation in acidic medium: overall reaction pathway

“…Pyrrhotite was not observed in XRD and Mössbauer experiments (data not shown). However, by using optical microscopy, Shao-Horn and Horn [13] provided evidence that the pyrrhotite is a minor phase in Alpha Aesar synthetic FeS 2 . Another explanation for the presence of Fe(III)-S bond types at the pyrite surface is some possible oxidation during the sample handling, despite great care having been taken to prepare a clean surface.…”

“…Similar band evolutions also observed in the presence of Cr(VI). [13] Of particular interest is that such drifts are thus not specifically due to the oxygen oxidation.…”

Hydrothermal synthesis of FeS2 for lithium batteries

“…Such improved electrochemical characteristics may be explained based on the differences in particle size or surface area between synthesized FeS 2 and natural pyrite. Subsequently, several serials of contrast experiments have been executed by Shao-Horn et al [4], which indicated that chemical composition, physical characteristics, and structure features greatly involved in discharge capacity of FeS 2 . In detail, levels of impurity contents, particle sizes, and grain sizes of synthesized FeS 2 are much lower than natural pyrite, probably resulting in a superior rate capability of lithium/ synthesized FeS 2 batteries.…”