The analysis of voltage fluctuations for the characterization of rechargeable alkaline manganese dioxide-zinc cells

Selected rechargeable ‘bobbin-type’ alkaline manganese dioxide (RAM)-zinc ‘AA’ cells were investigated. The cells had an identical design and chemistry with the exception that one group had a conductive coating applied to the inside of the nickel plated steel can which serves as the positive current collector. The electrochemical characterization of the cells was made with various techniques throughout their cycle life. The internal resistance at 1 kHz and electrochemical impedance spectroscopy (EIS) measurements were made at regular intervals on fully charged cells. The voltage fluctuations of the baseline discharge voltage were also recorded during discharge at three moments of the cells' cycle life. These voltage fluctuations were analyzed with a novel analysis technique which relies on the stochastic nature of the voltage fluctuations. The test performed revealed that the can coating contributed to an increase of the overall cell performance. Cells with a coated can exhibited a lower internal resistance and maintained this characteirstic even after extended periods of storage.