Fast charging technique for high power lithium iron phosphate batteries: A cycle life analysis

Reduction of the charging time for batteries is a crucial factor in the promotion of consumer interest in the commercialization of electric vehicles (EVs). Fast charging methods for EVs are therefore important to create and understand; however, fast charging is not tolerated by all lithium-ion chemistries because it typically affects the battery functionality and accelerates its aging mechanisms. A fast charging technique is proposed in this paper, and the results of extensive testing on a high power lithium iron phosphate cell subjected to the method are reported. The evaluation characterized the cell's capacity fade, cycle life, and energy efficiency with respect to the U.S. Advanced Battery Consortium (USABC) goals. The proposed charging algorithm permits a full recharging of the cell (0-100% SOC) in approximately 20 min, even after 4500 cycles are reached. The cycling scheme is characterized by high current discharges that reach specific powers of 400 W kg(-1). The results show that the proposed fast charging technique does not introduce any significant degradation effects on the cell and is energy efficient; they also show that performance is lost due to capacity fade rather than an increase in internal resistance. (C) 2013 Elsevier B.V. All rights reserved.