Publication Detail

A Method for the Analysis of High Power Battery Designs


Research Report

Suggested Citation:
Burke, Andrew (1999) A Method for the Analysis of High Power Battery Designs. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-99-06

The primary objective of this work was to develop a method for the analysis of batteries of various types that could be used as a tool to link battery design, performance, especially peak power density and energy density, and cost. There are numerous papers in the literature that model batteries in great detail starting with the governing partial differential equations that are solved in space, usually in one dimension, and time to determine the concentration and ion current distributions between the electrodes of the battery. These analyzes are valuable for understanding why batteries of a particular design behave as they do, but are cumbersome to use as a design tool to study the effect of battery geometry and material parameters on performance and life cycle and cost related characteristics, such as electrode thickness and area. It was also desired that the method be relatively easily adapted to the analysis of different battery types. One of the motivations for this work was to have a means of analyzing the trade-offs between energy density and peak power density as such trade-offs are often claimed as one of the reasons for using ultracapacitors to load level batteries in electric vehicles.

In order to meet these objectives, it was necessary that the method developed describe the configuration and materials in the cell/module in detail and include the principal electrochemical mechanisms that effect the voltage drop and current flow in the battery. In developing the general, but relatively simple, model of the battery discussed in this paper, the works presented in great detail in References were invaluable as sources of electrode material and electrolyte properties and discussions of the basic governing equations. Second sources of valuable information were various battery test reports, especially those from the Idaho National Engineering Laboratory that showed the discharge characteristics of several type of batteries and the battery internal design parameters based on post-test tear-down studies. This information was invaluable in determining input data for the present calculations and permitting the validation of the method developed for specific battery designs. Validation was done in terms of comparing calculated and measured values for Ah capacity and energy density for constant current discharges, peak power density for a specified voltage cutoff, cell resistance, and module weight and dimensions.