Microporous LiAlSiO₄ with high ionic conductivity working as a coating material and water adsorbent for LiNi_0.5Mn_1.5O₄ cathode

Trace water in the electrolyte can cause serious capacity fading, especially for the high voltage LiNi_0.5Mn_1.5O₄ (LNM) cathode. Here, we coat microporous LiAlSiO₄ on LNM particles using a citric acid-based sol-gel method. LiAlSiO₄ has been reported to be a good one-dimensional Li-ion conductor, ensuring that Li⁺ ions could cross this coating layer easily. Simultaneously, this LiAlSiO₄ coating layer contains many micropores with a radius of less than 2 nm, which could anchor H₂O molecules. The adsorption of H₂O suppresses the formation of HF, which further suppresses Mn dissolution of the LNM material, especially at high temperature. Finally, the LiAlSiO₄-modified LNM displays an obviously improved cycling stability, maintaining a capacity retention of 94.36% after 150 cycles at 1C and 55 °C.