Investigations on a High Conductivity Solid Electrolyte System, RbCI + CuCI

Solid electrolytes with high copper ionic conductivity and low electronic hole conductvi ity have been found in the RbC1 ~ CuC1 system. The highest conductivity of RbCu~C14 [75 mole percent (m/o) CuC1] was 2.25 • 10-~ (12-cm)- i at 25 ~ The conductivity has been measured as functions of tem-perature and of composition ~ X- ray patterns and thermal analyses indicate that the material is a new compound and not a mixture of the constituents. Solid electrolytes exhibit ing high conductivity such as Ag~SI (1, 2), MAg~I ~ (M _ K, Rb, and NH4) (3-5), KAg414CN (6), AgigI15P207 (7), si lver organic com-pounds (8-11), and ~-Al~Oa (12) have been found and all these are si lver ion or alkal i ion conductors. Re-cently, Takahashi and his co-workers (13-15) and Sammells et al. (16) have found new copper ion solid electrolytes with high ionic conductivity. These copper compounds were copper-organic compounds, and some are unstable when used in galvanic cells (16). The purpose of the present study is to prepare copper solid electrolytes without organic additives. In our preceding paper (17), many kinds of com-pounds in the cuprous halides and metal hal ides sys-tems have been examined by a-c conductivity mea-surements, and the new compounds with high con-ductivity at room temperature have been found in the RbC1 ~ CuC1 system. In the present study, the propert ies of the RbC1 ~-CuC1 system were investigated in more detai l by the electrical conductivity measurements and x- ray techniques