Study On FeS ₂ Materials And Their Properties In Hydrothermal Synthesis Of Pyrite

Thermal batteries have the inherent advantages of being very reliable, high power density and robust, they are widely used in military weapons. Since1980s Li-Si/FeS2serials thermal batteris have been extensively studied and FeS2became the primary cathode materials for the thermal battery techonology. The cathode materials FeS2are produced from natural minerals, the particle sizes of the natural pyrite are large and there are some impurities in the product that will affect the discharging performances of the thermal batteries.In this article, we have successfully prepared single phase pyrite with the reactants of Na2S·9H2O, FeSO4·6H2O and S via hydrothermal method. pH, temperatures and reaction time were investigated for the influences on the crystal structure of the final FeS2products. As the condition of preparing single phase pyrite is confirmed, micro pyrite powders with cubic morphologies and nano pyrite materials with plake like morphologies were produced, and then we studied the ifluences of particle sizes on the thermal stability and discharging performaces of the pyrite materials. The results reveal that the pH and temperatures have singnificant influences on the crystal structure of the FeS2products; the particle sizes and morphologies of the synthezing pyrite powders are greatly effected by the temperatures, reaction time and pH of the solutions, the capacity and filling factor of the autoclave also have some effects on the particle sizes of the final FeS2products; the decomposition temperatures of the pyrite materials reduce with the decreasing pyrite particle sizes; the discharging curves showed that the speficific capacity and power density of the single cell thermal batteries were improved as the paticle sizes decreasing at the early discharging period, and when discarging at large current densities, the potenials of the single cell thermal batteries could be imoproved greatly by decreasing the particle sizes.