Accelerating Li-Ion Diffusion in LiFePO4 by Polyanion Lattice Engineering

Despite the widespread commercialization of LiFePO4 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 BO33- substitution on tetrahedron PO43- to induce flexibility in the Li-ion diffusion channels, which are broadened simultaneously. The planar structure of BO33- may further provide additional paths between the channels. With these synergetic contributions, LiFe(PO4)(0.98)(BO3)(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 degrees 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 degrees C are realized.