Lithiation of Copper Selenide Nanocrystals.

The search for ion-conductive solid electrolytes for Li+ batteries is an important scientific and technological challenge with economic and sustainable energy implications. In this study, nanocrystals (NCs) of the ion conductor copper selenide (Cu2-y Se) were doped with Li by the process of cation exchange. Li2x Cu2-2x Se alloy NCs were formed at intermediate stages of the reaction, which was followed by phase segregation into Li2 Se and Cu2 Se domains. Li-doped Cu2-y Se NCs and Li2 Se NCs exhibit a possible SI phase at moderately elevated temperatures and warrant further ion-conductance tests. These findings may guide the design of nanostructured super-ionic electrolytes for Li+ transport.