Accelerating Li‐Ion Diffusion in LiFePO4 by Polyanion Lattice Engineering

Abstract Despite the widespread commercialization of LiFePO 4 as cathodes in lithium‐ion batteries, the rigid 1D Li‐ion diffusion channel along the [010] direction strongly limits its fast charge and discharge performance. Herein, lattice engineering is developed by the planar triangle BO 3 3− substitution on tetrahedron PO 4 3− to induce flexibility in the Li‐ion diffusion channels, which are broadened simultaneously. The planar structure of BO 3 3− may further provide additional paths between the channels. With these synergetic contributions, LiFe(PO 4 ) 0.98 (BO 3 ) 0.02 shows the best performance, which delivers the high‐rate capacity (66.8 mAh g −1 at 50 C) and long cycle stability (ultra‐low capacity loss of 0.003% every cycle at 10 C) at 25 °C. Furthermore, excellent rate performance (34.0 mAh g −1 at 40 C) and capacity retention (no capacity loss after 2500 cycles at 10 C) at −20 °C are realized.