Lithium iron phosphate

Lithium iron phosphate or lithium ferro-phosphate (LFP) is an inorganic compound with the formula LiFePO4. It is a gray, red-grey, brown or black solid that is insoluble in water. The material has attracted attention as a component of lithium iron phosphate batteries, a type of Li-ion battery. This battery chemistry is targeted for use in power tools, electric vehicles, solar energy installations and more recently large grid-scale energy storage. Most lithium batteries (Li-ion) used in consumer electronics products use cathodes made of lithium compounds such as lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), and lithium nickel oxide (LiNiO2). The anodes are generally made of graphite. Lithium iron phosphate exists naturally in the form of the mineral triphylite, but this material has insufficient purity for use in batteries. With general chemical formula of LiMPO4, compounds in the LiFePO4 family adopt the olivine structure. M includes not only Fe but also Co, Mn and Ti. As the first commercial LiMPO4 was C/LiFePO4, the whole group of LiMPO4 is informally called “lithium iron phosphate” or “LiFePO4”. However, more than one olivine-type phase may be used as a battery's cathode material. Olivine compounds such as AyMPO4, Li1−xMFePO4, and LiFePO4−zM have the same crystal structures as LiMPO4, and may replace it in a cathode. All may be referred to as “LFP”. Manganese, phosphate, iron, and lithium also form an olivine structure. This structure is a useful contributor to the cathode of lithium rechargeable batteries. This is due to the olivine structure created when lithium is combined with manganese, iron, and phosphate (as described above). The olivine structures of lithium rechargeable batteries are significant, for they are affordable, stable, and can be safely used to store energy. Arumugam Manthiram and John B. Goodenough first identified the polyanion class of cathode materials for lithium ion batteries. LiFePO4 was then identified as a cathode material belonging to the polyanion class for use in batteries in 1996 by Padhi et al.