Coupling Anti-Site Defect and Lattice Tensile Stimulates Facile Isotropic Li-ion Diffusion.

Despite widely used as a commercial cathode, the anisotropic one-dimensional channel hopping of lithium ions along the [010] direction in LiFePO 4 prevent its application in fast charging conditions. Herein, we employ an ultra-fast non-equilibrium high-temperature shock (HTS) technology to controllably introduce the Li-Fe anti-site defects and tensile strain into the lattice of LiFePO 4 . This design makes the study of the effect of the strain field on the performance further extended from the theoretical calculation to the experimental perspective. The existence of Li-Fe anti-site defects makes it feasible for Li + to move from the 4a site of the edge-sharing octahedra across the ab plane to 4c site of corner-sharing octahedra, producing a new diffusion channel different from [010]. Meanwhile, the presence of a tensile strain field reduces the energy barrier of the new two-dimensional diffusion path. In the combination of electrochemical experiments and first-principles calculations, we demonstrate that the unique multi-scale coupling structure of Li-Fe anti-site defects and lattice strain promotes isotropic two-dimensional inter-channel Li + hopping, leading to excellent fast charging performance and cycling stability (high-capacity retention of 84.4% after 2000 cycles at 10 C). The new mechanism of Li + diffusion kinetics accelerated by multi-scale coupling can guide the design of high-rate electrodes. This article is protected by copyright. All rights reserved.