Constructing LiF@spinel dual shell to suppress interfacial side reactions of Li-rich cathode materials

Li-rich oxides are considered to be the most promising candidate cathode materials for high-energy Li-ion batteries due to their high specific capacity. However, the lack of a stable surface structure to inhibit interfacial side reactions is a key factor hindering the widespread adoption of Li-rich materials. In this work, a stable LiF@Spinel dual shell is constructed on the surface of Li-rich materials, in which spinel is formed by in-situ surface reconstruction and LiF is bonded to spinel through the Ni-F bond. The spinel serves as a buffer layer between the LiF coating and the Li-rich oxide, providing a three-dimensional Li-ion diffusion channel to improve the Li-ion diffusion coefficient, while the outer LiF plays a critical role in isolating the cathode from the electrolyte. Under the above dual effect, the interfacial side reactions of Li-rich materials are inhibited, thus improving their cycle stability. The obtained LiF@Spinel-coated Li-rich cathode exhibits enhanced capacity retention of 81.5% after 150 cycles at the current density of 2C, much better than 63.2% of the pristine Li-rich sample. These findings demonstrate that the construction of LiF@Spinel dual shell is a successful strategy for the modification of Li-rich materials.