Review on comprehending and enhancing the initial coulombic efficiency of Li-rich Mn-based cathode materials in lithium-ion batteries

Abstract

Li-rich Mn-based materials have received extensive attention in the field of energy storage due to their unparalleled high energy density. Due to the poor rate performance and cycling stability of this material, researchers have carried out a lot of research recently looking at the failure mechanism and modification strategies for these Li-rich materials, which has greatly improved their electrochemical performance. However, many researchers have neglected to account for the initial coulomb efficiency (ICE), which is a key electrochemical parameter. The low ICE has become one of the important factors restricting the commercialization of Li-rich materials. Understanding the reasons for the low ICE of Li-rich materials and analyzing the nature of the impact of common modification strategies on the ICE of Li-rich materials are ways to achieve a high ICE of Li-rich materials. In this review, we first determine that the oxygen release reaction on the material surface and the low diffusion rate of Li-ion between the layers of Li-rich materials are the key factors that cause the low ICE of Li-rich materials. Then, the mechanism and effect of common modification strategies such as structure design, surface modification and doping engineering on the ICE of Li-rich materials are analyzed in detail in this review. Finally, we discuss new research directions and future research trends of ICE. This work not only improves the theoretical basis for the preparation of Li-rich materials with a high ICE, but also inspires more researchers to pay attention to and participate in the exploration of the ICE of Li-rich materials.