Leakage current in electrochemical systems having common electrolyte paths. I: Experimental measurements

Common electrolyte paths in bipolar batteries waste capacity and energy via shunt currents. Historically, the degree of loss has been determined by (i) estimation using electrical analogues, (ii) measurement of magnetic fields around cell channels, or (iii) measuring voltages along electrolyte channels and manifolds. Critical review raised questions about these historical approaches. Experiments subsequently supported the criticisms and the questions. Consideration was given to charge transfer at electrodes, coupling of anodic and cathodic processes, the nature of the charge carriers in the electrode and in the electrolyte. A special symbol for impedance to ionic flow was used. From these considerations a method of simulating shunt currents was developed. Measurements were then taken to determine bipolar leakage current between contiguous cells, and to determine other intercell currents. The bipolar cell currents were found,as expected, and measured; other intercell currents were negligible as the experiments were designed. This experimental information will be used in a subsequent paper to formulate a theoretical approach to leakage currents and to design studies of common electrolyte systems.