PNNL

Abstract

Lithium ion batteries to power plug-in hybrid electrical vehicles (PHEV) must store more energy per unit volume and weight, and be capable of undergoing many thousands of charge/discharge cycles. The existing battery technologies have serious limitations such as high cost, limited capacity and lifetime. One way to significantly increase the energy storage capacity of lithium ion batteries is to increase cell voltage by using high voltage cathode materials. For example, the LiNi1/3Mn1/3Co1/3O2 (NMC) system has a capacity of ca. 170 mAh/g when charging to 4.3 V vs. Li+/Li. Increasing the voltage results in a significant increase in capacity with values to 200 mAh/g at 4.5 V and approaching 250 mAh/g at even higher potentials. However, most of the current electrolytes are not stable at such high voltages and lead to fast fade in battery capacity. Therefore, electrolytes capable of enduring high voltages are required for the next generation of lithium ion batteries. It is well known that electrolyte components - salt, solvents and additives, are critical to the success of lithium ion batteries in high energy and power applications. Such electrolyte components and their compositions have large effects on the properties and performances of the final electrolytes and batteries containing them. In this paper, the electrochemical properties and performances of non-aqueous electrolytes containing the state-of-the-art solvents and lithium salts will be investigated. The combination of a high voltage cathode and the high voltage stable electrolyte will be evaluated and presented.