Aegis of Lithium-Rich Cathode Materials via Heterostructured LiAlF4 Coating for High-Performance Lithium-Ion Batteries.

Lithium-rich oxides have been regarded as one of the most competitive cathode materials for next-generation lithium-ion batteries due to their high theoretical specific capacity and high discharge voltage. However, they are still far from being commercialized due to low rate capability and poor cycling stability. In this study, we propose a heterostructured LiAlF4 coating strategy to overcome those obstacles. The as-developed lithium-rich cathode material shows outstanding performance including a high reversible capacity (246 mA h g-1 at 0.1C), excellent rate capability (133 mA h g-1 at 5C), and ultralong cycling stability (3000 cycles). Comparing with those of pristine and AlF3-coated lithium-rich cathode materials, the enhanced performances can be attributed to the introduction of the lithium-ion-conductive nanolayer and the generation of nonbonding O n- species in the active material lattice, which enable rapid and effective lithium ion transport and diffusion. Our work provides a new strategy to develop high-performance lithium-rich cathode materials for high-energy-density lithium-ion batteries.