A Novel Inorganic Low Melting Electrolyte for Secondary Aluminum-Nickel Sulfide Batteries

A new, inorganic low melting electrolyte with the composition LiA1C14-NaA1C14-NaA1Br4-KA1C14 (3:2:3:2) [or equiva-lently LiA1Br4-NaA1C14-KA1C14 (3:5:2)] has been developed. The melting point for this neutral melt is 86°C; the decom-position potential is approximately 2.0V; the ionic conductivity is measured in the range 97°-401°C and is 0.142s cm-1 at 100°C, and the density is 2.07g cm-3. The conductivity seems to be an almost linear combination Of the conductivities of the four individual halo salts which form the melt. Other examined higher melting mixtures exhibit conductivities deviat-ing less than-+ 10 % from their combination expectations. The low melting electrolyte is employed in the rechargeable bat-tery system A1/electrolyte/Ni3S2 at 100°C. The open-circuit voltage of this system is from 0.82 to 1.0V. Dendrite-free alumi-num deposits are obtained. The cycling behavior of the battery system is reported. The need for better rechargeable batteries is well-known. Most authors working with molten salt batteries have used alkali metal anodes. In the last few years, alumi-num has instead been investigated for battery suitability, especially in Denmark (1-3) and Japan (4). Melts of NaC1-AIC13 or KCI-NaC1-A1C13 have been the most popula