Lithium/sulfur dioxide rechargeable cells with cosolute or with tetrachloroaluminate electrolytes

Lithium salts ordinarily slightly soluble in liquid sulfur dioxide may be made substantially soluble by the addition of soluble nonlithium salts, which apparently serve to increase the dielectric constant of the solution. Examples include KSCN/LiSCN and CsBr/LiBr. The chemical design allows the construction of cells without the need for organic cosolvents. The resistance to capacity fading in Li/SO₂/carbon cells with lithium tetrachloroaluminate may be improved by increasing the ratio of aluminum to sulfur dioxide from AlCl ₄^-/SO₂=1:6 to 1:3, and by lowering the concentration of hydrolysis products. Calcium tetrachloroaluminate lowers the freezing point without interfering with lithium cycling. Improved safety and overall cycling efficiency have also been observed