Lithium Iron Phosphate: A Promising Cathode-Active Material for Lithium Secondary Batteries (PDF)

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.This monograph provides an overview of the research effort already expended on developing lithium iron phosphate as a positive electrode material for lithium batteries because it has the potential to replace the presently used transition metal oxides. The book is written so as to serve the needs of researchers in the field as well as those of teachers and students of electrochemistry; as a textbook.The text is divided into twelve sections. The first section starts with a general introduction to batteries and battery components and then leads the reader into the specific topic of lithium iron phosphate. Section two details the key characteristics of lithium iron phosphate which make it so attractive to battery chemists and the battery industry. The limitations of the material, which should be overcome in order to achieve better performance, are also described. The properties of lithium iron phosphate are compared, wherever possible, with those of transition-metal oxides. Section three outlines the synthesis methods generally used for preparing lithium iron phosphate, together with particular examples. The synthesis of carbon-coated lithium iron phosphate is presented in section four; stressing the importance of the various strategies used to obtain the carbon coating. Because the synthesis parameters have a marked effect upon the physical and electrochemical properties of the resultant material, section five is devoted to a discussion of this aspect of both coated and uncoated lithium iron phosphate. Section six deals with the synthesis and properties of the metal ion-doped phosphate. The various parameters that have a significant influence over the electrochemical performance are discussed in section seven. How other components, such as the anode and electrolyte, and the operating temperature, strongly affect the properties of the batteries is outlined in section eight. Section nine deals with the safety and storage of lithium batteries with phosphate-based cathodes. A brief discussion of theoretical and modeling studies carried out on the phosphate forms section ten. An outline of studies performed on other members of the phosphate olivine family is presented in section eleven. Finally, section twelve provides a brief summary of the whole text.Altogether, this makes this work the primary source of comprehensive data on the material.Nickel-cadmium and nickel-metalhydride batteries have largely become obsolete, especially in portable electronic devices. Taking their place are lighter, more efficient lithium batteries, which are still in development to improve their performance and safety at lower cost. Here Cheruvally (chemistry, Vikram Sarabhai Space Center, India) reviews research on developing lithium iron phosphates as positive electrode materials that have the potential to replace transition metal oxides. She gives basic information on batteries as electrochemical energy sources, then describes lithium iron phosphate as a cathode material and presents nearly a dozen different methods of synthesizing it for experimentation or production. She describes the influence of synthesis parameters on the properties of lithium iron phosphates, the synthesis and properties of metal ion-doped lithium iron phosphate, the influence of different parameters (including cell components and operating temperature) on the cathode, safety and storage issues, theoretical and modeling studies, and phosphate olivines as cathode-active materials.