Novel Br⁻ ion conducting solid electrolyte based on LaOBr

Abstract

Highly Br ¹ ion conducting solid electrolytes were developed by replacing La 3+ ion site in LaOBr with lower valent Sr 2+ and Ca 2+ ions to form Br ¹ ion vacancies for Br ¹ ion conduction with suppressing the sample decomposition. By doping two kinds of divalent cations simultaneously into LaOBr lattice, high amount of Br ¹ ion vacancy was successfully introduced compared to the previously reported La 0.9 Sr 0.1 OBr 0.9. Among the samples prepared, the highest Br ¹ ion conductivity was obtained for the La 0.85 Sr 0.10 Ca 0.05 OBr 0.85 solid, which was ca. 5 times higher than that of La 0.9 Sr 0.1 OBr 0.9 .

Enhancement of bromide ion conductivity in lanthanum oxybromide based solids by doping divalent zinc ion with high electronegativity

“…By selecting Zn 2+ ion as the co-dopant of Sr 2+ ion into the La 3+ ion site, higher amount of Br − ion vacancies were successfully formed compared with the La 0.95−x Sr x Ca 0.05 OBr 0.95−x solids reported previously, and it was clarified that the La 0.80 Sr 0.15 Zn 0.05 OBr 0.80 solid showed the highest Br − ion conductivity in the LaOBr-type solids, which was ca. 4 times higher than those of the previous reported La 0.85 Sr 0.10 Ca 0.05 OBr 0.85 solid [24].…”

“…In conclusion, Br − ion highly conducting La 1−x−y Sr x Zn y OBr 1−x−y solids were synthesized by the partial replacement of the La 3+ sites in Sr 2+ -doped LaOBr for the Zn 2+ [24], La 0.90 Sr 0.10 OBr 0.90 [21] and LaOBr [21]. ions having high electronegativity and small ionic-size in order to increase the number of Br − ion vacancies with holding the LaOBr structure.…”

“…In our previous studies [21,23], the improvement of conductivity for the LaOBr solid has been realized by partially replacing the La 3+ sites in LaOBr with lower valent alkaline-earth ions (Ca 2+ , Sr 2+ ) to introduce Br − ion vacancy in the structure. Among them, the La 0.90 Sr 0.10 OBr 0.90 solid showed the highest conductivity because of a large number of Br − ion vacancies were generated as well as the lattice expansion by partial replacement of La 3+ [24].…”

Mechanisms of point defect formation and ionic conduction in divalent cation-doped lanthanum oxybromide: first-principles and experimental study

“…16,19 Synthesizing mixed-anion compounds is one approach to overcome these disadvantages, [20][21][22][23][24][25] and lanthanum oxyhalide, LaOX (X: Cl, Br, and I), is one such halide-based mixedanion. [26][27][28][29][30] LaOX-based compounds are reported to exhibit halide ion conductivities of about 7.2 × 10 −3 , 1.0 × 10 −3 , and 4.4 × 10 −6 S cm −1 at 400 °C for oxychrolide, 26 oxybromide, 29 and oxyiodide, 30 respectively, despite the larger ionic radii of halide ions. In addition, these compounds are insoluble in water and thermodynamically more stable than simple halides.…”

“…Pure LaOBr has low ionic conductivity, and several divalent cations such as Mg, Ca, Zn, and Sr were added to improve its conductivity. 18,28,29,33 From the experimental approach, the Br − ion conduction was demonstrated by the dc electrolysis of La 0.90 Sr 0.10 OBr 0.90 , and the polarization behavior denied the O 2− ion migration. 33 The conduction mechanism in doped LaOBr is expected to be related to the halide ion vacancies similar to the LaOCl system, although this is not verified theoretically.…”