Revisiting polyanionic LiFePO4 battery material for electric vehicles

Abstract

Although oxide cathodes have been widely used in these Li-ion batteries, these cathodes suffer from instability of the oxygen close-packed structure. In contrast, polyanionic phosphates such as LiFePO4 have incredible lattice stability and safety features owing to the strong covalent bond of P-O, which constrains the oxygen atoms and minimizes the defects of the oxygen site, resulting in stable frameworks. In addition, the presence of the strong P-O covalent bond stabilizes the anti-bonding transitional metal redox couple through an M-O-P inductive effect to generate a relatively high potential. Hence, polyanionic LiFePO4 has been an ideal choice of cathode materials for batteries deployed in electric vehicles. In this review, we revisit the basic features and development of LiFePO4, as an attempt to speeding its future deployment in massive electric vehicles.