Table of Contents Author Guidelines Submit a Manuscript
International Journal of Electrochemistry
Volume 2012 (2012), Article ID 395838, 10 pages
http://dx.doi.org/10.1155/2012/395838
Research Article

Quantifying Cell-to-Cell Variations in Lithium Ion Batteries

1National Renewable Energy Laboratory, Golden, CO 80401, USA
2University of South Carolina, Columbia, SC 29204, USA

Received 26 March 2011; Accepted 4 October 2011

Academic Editor: Dong Shu

Copyright © 2012 Shriram Santhanagopalan and Ralph E. White. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Lithium ion batteries have conventionally been manufactured in small capacities but large volumes for consumer electronics applications. More recently, the industry has seen a surge in the individual cell capacities, as well as the number of cells used to build modules and packs. Reducing cell-to-cell and lot-to-lot variations has been identified as one of the major means to reduce the rejection rate when building the packs as well as to improve pack durability. The tight quality control measures have been passed on from the pack manufactures to the companies building the individual cells and in turn to the components. This paper identifies a quantitative procedure utilizing impedance spectroscopy, a commonly used tool, to determine the effects of material variability on the cell performance, to compare the relative importance of uncertainties in the component properties, and to suggest a rational procedure to set quality control specifications for the various components of a cell, that will reduce cell-to-cell variability, while preventing undue requirements on uniformity that often result in excessive cost of manufacturing but have a limited impact on the cells' performance.