Li ion conductivity of solid electrolyte, LiMInBr (M=Mg, Ca, Sr, Ba)

Li 3−2 x M x InBr 6 (M=Mg, Ca, Sr, Ba; x =0–1.0) was synthesized and the cation substitution effect was investigated by means of X-ray diffraction, 7 Li and 115 In nuclear magnetic resonance (NMR), and AC conductivity measurements. In Li 3−2 x Mg x InBr 6 , the lattice constants a and c increased with an increase of x , but b and β did not show significant changes. In the high-temperature phase for Li 3−2 x M x InBr 6 (M=Mg, Ca, Ba), the conductivity decreased with x , accompanied by a broadening of the 115 In NMR spectra. In Li 3−2 x Sr x InBr 6 ( x ≤0.7), the conductivity of the high-temperature phase also decreased with an increase of x , but LiSrInBr 6 showed almost the same conductivity to Li 3 InBr 6 . On the other hand, the conductivity of the low-temperature phase in Li 3−2 x Mg x InBr 6 ( x ≤0.4) increased with x , associated with a narrowing of the 7 Li NMR spectra.