Novel bromide anion conducting refractory solid electrolytes based on lanthanum oxybromide

A new type of high bromide anion conducting solid was artificially designed with the solids based on lanthanide oxybromide (LnOBr). LnOBr is selected as it is insoluble in water and also highly stable at temperatures around 800°C. The enhancement of Br− anion conductivity was successfully realized by creating Br− ion vacancies by doping divalent cation in the Ln site of the LnOBr host lattice. The Br− anion conductivity was the highest among the conventional bromide anion conducting solids such as Pb0.99K0.01Br1.99 (373°C) and CsPbBr3 (500°C) which contain toxic lead in them. The Br− anion conductivity of LnOBr based solid enters into the practically useful region (σ > 10−3 Sċcm−1).