Three-dimensional Li-ion transportation in Li2MnO3-integrated LiNi0.8Co0.1Mn0.1O2

Abstract

Ni-rich layered cathodes (LiNixCoyMnzO2) have recently drawn much attention due to their high specific capacities. However, the poor rate capability of LiNixCoyMnzO2, which is mainly originated from the two-dimensional diffusion of Li ions in the Li slab and Li+/Ni2+ cation mixing that hinder the Li+ diffusion, has limited their practical application where high power density is needed. Here we integrated Li2MnO3 nanodomains into the layered structure of a typical Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) material, which minimized the Li+/Ni2+ cationic disordering, and more importantly, established grain boundaries within the NCM811 matrix, thus providing a three-dimensional diffusion channel for Li ions. Accordingly, an average Li-ion diffusion coefficient (DLi+) of the Li2MnO3-integrated LiNi0.8Co0.1Mn0.1O2 (NCM811-I) during charge/discharge was calculated to be approximately 6*10−10 cm2 S−1, two times of that in the bare NCM811 (3*10−10 cm2 S−1). The capacity delivered by the NCM811-I (154.5 mAh g−1) was higher than that of NCM811 (141.3 mAh g−1) at 2 C, and the capacity retention of NCM811-I increased by 13.6% after 100 cycles at 0.1 C and 13.4% after 500 cycles at 1 C compared to NCM811. This work provides a valuable routine to improve the rate capability of Ni-rich cathode materials, which may be applied to other oxide cathodes with sluggish Li-ion transportation.