A Method for the Analysis of High Power Battery Designs

Proceedings of the 32nd Intersociety Energy Conversion Engineering Conference, Honolulu, HI, July 27 - August 1, 1997 A spreadsheet model for the analysis of batteries of various types has been developed that permits the calculation of the size and performance characteristics of the battery based on its internal geometry and electrode/electrolyte material properties. The method accounts for most of the electrochemical mechanisms in both the anode and cathode without solving the governing partial differential equations. The spreadsheet calculations for a particular battery design are performed much like a battery test in that the C/3 capacity of the battery to a specified cut-off voltage is determined and then the pulse power capability at a given state-of-charge is determined by finding the maximum current density (A/cm2) for which the cell voltage equals a specified minimum value. For a multi-cell module, the module characteristics are calculated using the cell results and packaging input information. The spreadsheet model has been validated for existing lead-acid (Sonnenschein), nickel cadmium (Saft), and nickel metal hydride (Ovonic) batteries for which test data and internal geometry information are available. Various battery designs were then evaluated using the method to show how batteries having high power densities (greater than 500 W/kg) could be designed. The spreadsheet model permitted the determination of the critical design parameters for high power lead-acid, nickel cadmium, and nickel metal hydride batteries.