In-situ surface modification to stabilize Ni-rich layered oxide cathode with functional electrolyte

Abstract Ni-rich layered oxides are regarded as the promising candidate for high energy density lithium-ion batteries owing to the high specific capacity. However, Ni-rich layered oxides suffer a rapid capacity fade, which is related to the undesirable structure evolution during cycling. Herein, an in-situ surface modification strategy by using Al 2 O 3 nanofibers as electrolyte additive is adopted to enhance the crystallographic, morphological, component, and electrochemical stability of LiNi 0.88 Co 0.09 Al 0.03 O 2 during cycling at both the particle and electrode level. The coating layer can be in-situ formed on the cathode surface after injecting the functional electrolyte into the cell. The integrated spherical morphology of secondary particles on the modified cathode is maintained during cycling without harmful microcracks. In the meantime, the coating layer protects the cathode from HF corrosion during cycling, which can reduce the dissolution of transition-metal ions and insure relatively uniform spatial distribution of the constituents across the cathode as detected by laser-induced breakdown spectroscopy (LIBS). Consequently, the modified cathode shows the improved stability with the high initial capacity of 198.1 mAh g −1 and good capacity retention after 800 cycles at room temperature. Moreover, the modified cathode also exhibits promising performance at higher operating temperature (55 °C) or higher charge potential (4.6 V).