Evaluation of Effects of Additives in Wound Li-Ion Cells Through High Precision Coulometry

Abstract

LiCoO(2)/graphite and LiCoO(2)/Li(4)Ti(5)O(12) wound prismatic cells were examined with and without electrolyte additives using the high precision charger at Dalhousie University. The additives tested were vinylene carbonate, trimethoxyboroxine, and lithium (bis) trifluoromethanesulfonimide. The voltage curves, charge and discharge end point positions, fade, and coulombic efficiency were compared to gain an understanding of the effects of the electrolyte additives on the cells. Long term cycling data (capacity loss over 750 cycles) was compared with predicted lifetime measurements based on high precision coulometry. Design of experiments was used in order to help interpret the results from the 20 groups of cells tested. (C) 2011 The Electrochemical Society. [DOI:10.1149/1.3531997] All rights reserved.