Low temperature electrochemical cells with sodium β″-alumina solid electrolyte (BASE)

Cells of Daniell-type with copper–zinc electrochemical couples and sodium β″-alumina solid electrolyte (BASE) were constructed. The cathode consisted of copper in contact with its ions (Cu/Cu2+) while zinc in contact with its ions (Zn/Zn2+) constituted the anode. Dimethyl sulfoxide (DMSO) containing 1 M NaBF4 was used as the liquid electrolyte. The configuration of the cell constructed can be written as follows:Zn(s)/ZnCl2(DMSO)(0.1 M), NaBF4(1 M)/BASE/NaBF4(1 M), CuCl2(DMSO)(0.1 M)/Cu(s)The cell was subjected to charge–discharge cycles at 100 °C. The BASE discs were found to be stable even after the cell was subjected to several electrochemical charge–discharge cycles. Cells were also constructed using BASE discs with porous BASE surface layers introduced to lower the interfacial resistance. Cells with surface modified BASE exhibited a lower resistance in comparison to those using unmodified BASE. XRD and SEM analyses indicated that no detectable degradation of BASE discs occurred after cell testing. Preliminary cell tests were also conducted with NaCF3SO3 in place of NaBF4.