ADMITTANCE SPECTROSCOPY OF SEALED SECONDARY BATTERIES

The admittance of sintered NiCd alkaline and Pb-acid-sealed batteries was investigated in the frequency range 10** minus **2-10**4 Hz at 253, 293, and 323 K, with small signals of 1-10 mv amplitude under potentiostatic control to keep the direct current to a minimum value. Fully charged and fully discharged states of these batteries were investigated, the latter corresponding to relatively 'slow' and 'fast' discharges. The results are discussed in terms of known electrochemical reactions in these two types of batteries and assignments are made of the bulk electrolyte resistance, the interfacial electrochpemical reaction, and the transport of ionic species through the pores of the nonconducting matter surrounding the electrodes, as well as a 'structural' inductance term.