Tailoring bulk Li+ ion diffusion kinetics and surface lattice oxygen activity for high-performance lithium-rich manganese-based layered oxides

Abstract

Lithium-rich manganese-based layered oxides (LRMOs) offer joint cationic and anionic redox at a high voltage, thus promising high energy density for lithium-ion batteries (LIBs). However, the restive anion redox is also connected with poor rate performance, severe capacity fading, and continuous voltage decay. Herein, a successful strategy for enhancing the Li+ ion diffusivity and structure stability of LRMOs is proposed. The obtained material possesses high cationic and anionic redox activity due to the introduction of Te6+. Moreover, a heterogeneous protective layer that is composed of acid-resistant Mg3(PO4)2 and self-induced cation-disordered phase with passivated lattice oxygen is verified to be located on the surface of the material, thereby restraining the structural degeneration. Benefitting from the unique architecture, the modified material presents a favorable cycling performance and excellent rate capability (178.8 mA h g-1, 10 C). More importantly, the voltage decay is significantly suppressed during cycling. The finding here exhibits the importance of activating cationic and anionic redox in the bulk and passivating surface oxygen for enhancing reversible capacity at high rates and improving structural stability, providing a ponderable way to promote the electrochemical performance of LRMOs.