Lithium ion batteries are attractive systems for high-power application in hybrid electric vehicles (HEVs) because of their outstanding rate capabilities. In the past four years, Argonne National Laboratory has been investigating the lithium nickel cobalt system as a potential system for high-power batteries for HEV application. However, this system shows limited calendar life and safety concerns that are the two main barriers to the commercialization of lithium ion batteries in HEVs. Recently, Argonne has been investigating a new system based on lithium manganese oxide as an alternative system for high-power applications. This system offers several advantages such as low cost, better abuse tolerance and, more importantly, outstanding rate capability. The LiMn-2O-4/graphite Li-ion battery based on a LiPF-6-based electrolyte exhibits excellent cycle life and good rate capabilities at ambient temperature; however, at elevated temperatures, these batteries show poor electrochemical performance, namely, short cycle life and poor storage performance because of manganese dissolution in the electrolyte. This degradation of the spinel delays its wide acceptance by battery manufacturers.
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