Book excerpt: Since the first development of lithium-ion batteries in the early 1990’s, there have been tremendous advances in the science and technology of these electrochemical energy sources. At present, lithium batteries dominate the field of advanced power sources and have almost entirely replaced their bulkier and less energetic counterparts such as nickel-cadmium and nickel-metalhydride batteries; especially in portable electronic devices. But lithium batteries are still the object of continuing intense research aimed at making further improvements in performance and safety, at lower cost, so as to make them suitable for higher-power and more demanding applications such as electric vehicles. The research and development of new electrode materials, particularly for cathodes, having an improved electrochemical performance has always been a matter of changing focus. Thus, olivine, lithium iron phosphate, has attracted considerable attention in recent years as a safe, environmentally friendly, extremely stable and very promising cathode material.