Lithium metal phosphates, power and automotive applications

Abstract

Lithium metal phosphate materials are the newest generation of active materials. With the limited number of cathode materials available at present and the prevalence of transition metal oxide cathodes, phosphates are able to answer the rising safety concerns surrounding the oxide chemistry. These inherent safety limitations have until now prevented lithium ion batteries in general from entering the large format applications markets such as electric and hybrid electric vehicles. Iron-based olivine phosphate has been the focus of extensive research: intrinsic thermal stability and continual improvement of its performance characteristics have geared the industry to a fast track adoption of this chemistry for the larger format applications. Recently developed vanadium-based phosphates possess operating voltages of 3.65 V for Li 3V 2(PO 4) 3 and 4.05 V for LiVPO 4F, both of which are higher than the iron-based phosphate. The high power capability of Li 3V 2(PO 4) 3 makes it ideal for applications that require power; LiVPO 4F on the other hand has high energy and a desirable cycling characteristic that makes it ideal for energy-demanding applications such as PHEV and EV. These materials are the best fit for the ever-increasing demand for energy, power and thermal stability that is essential in the large format arena.