Complex impedance studies of lithium iodine batteries

Complex impedance spectra of conductivity cells containing iodine-poly-2-vinylpiridine cathode material has been taken by two- and four-probe techniques. The impedance spectra contain a current-independent bulk resistance in series with a current-dependent interfacial resistance. The current-dependent interfacial resistance has the characteristics expected of a charge-transfer resistance. Electronically blocked (lithium-lithium iodide) electrodes give the same result as nonblocked (stainless steel) electrodes. This is exactly what would be expected if the medium were an ionic conductor. Complex impedance spectra of lithium-iodine batteries show additional structure, as might be expected, but are consistent with results from the conductivity cells