Transport properties of mechanochemically synthesized copper (I) selenide for potential applications in energy conversion and storage

This work studied the thermal stability, electrical, and thermoelectrical properties of copper(I) selenide, Cu₂Se synthesized by high-energy milling in a planetary ball mill. The phase composition was investigated by X-ray powder diffraction analysis and scanning electron microscopy. The conversion of the precursors during mechanochemical synthesis and the stability of the product was monitored by thermal analysis. The dependence of electrical properties on the product porosity was observed. For the densification of Cu₂Se, the method of spark plasma sintering was applied to prepare suitable samples for thermoelectric characterization. High-temperature thermoelectric properties of synthetic Cu₂Se were compared to its natural analogue-mineral berzelianite in terms of its potential application in energy conversion. Based on the results a relatively high figure-of-merit, ZT parameter (~ 1.15, T = 770 K) was obtained for undoped Cu₂Se, prepared by rapid mechanochemical reaction (5 min). Cyclic voltammetry measurements of Na/NaClO₄/Cu₂Se cell implied that mechanochemically synthesized Cu₂Se could be used as a promising intercalation electrode for sodium-ion batteries.