Spinel LiNi0.5Mn1.5O4 shell enables Ni-rich layered oxide cathode with improved cycling stability and rate capability for high-energy lithium-ion batteries

Abstract

Increasing the charging cut-off voltage is an effective strategy to achieve high energy density Ni-rich layered oxide cathode materials, however the dramatic deterioration of cycling lifespan and thermal stability still remain great challenges in large-scale practical applications. Herein, a rationally designed core-shell structure LiNi0.9Co0.1O2@LiNi0.5Mn1.5O4 composite composed of spinel structure Mn-rich LiNi0.5Mn1.5O4 shell and layered structure Ni-rich LiNi0.9Co0.1O2 core is proposed to enhance the structure stability and thermal stability under high-voltage application scenario. Compared to the pristine LiNi0.9Co0.1O2 cathode, the core-shell structure LiNi0.9Co0.1O2@LiNi0.5Mn1.5O4 composite with optimized LiNi0.5Mn1.5O4 shell exhibits high reversible specific capacity (195.5 mA h g − 1 at 0.5 C), remarkable cycling stability (86% capacity retention after 100 cycles) and superior rate capability (162.5 mA h g − 1 at 5.0 C) within 2.8 V-4.5 V. The comprehensively improved electrochemical performance is mainly attributed to the Mn-rich LiNi0.5Mn1.5O4 shell, which not only effectively prevents the phase transition and microstructural collapse, but also ameliorates the Li+ transport ability, high-voltage charging capability and thermal stability. Such novel core-shell structure LiNi0.9Co0.1O2@LiNi0.5Mn1.5O4 composite as promising cathode is highly expected to greatly promote the practical application of high energy density lithium-ion batteries.