PNNL

Abstract

Ever-increasing markets for electric vehicles (EVs) have brought tremendous attention to the need for high energy density batteries with reliable electrochemical performances. However, even the successfully commercialized lithium (Li)-ion batteries (LIBs) have still faced challenges about price and safety concerns when they are used as the power sources for EVs. From the electrode materials point of view, layered transition metal (TM) oxides (referred to as LiMO2 (M = Ni, Mn, Co, Al, etc., LMO) and Li-rich xLi2MnO3·(1–x)LiMO2 (LMR)) have been considered promising candidates because of their advantages regarding theoretical capacity, operating voltage and manufacturing cost. Unfortunately, despite the extensive efforts for development and optimization so far, layered TM oxides still have not completely reached out the expectation for EV applications due to their intrinsic stability issues during the electrochemical processes. To address these problems, a variety of surface modification strategies have been conducted. Herein, we summarize the achievements of surface modifications categorized by the functionality of addressing stability issues in layered TM oxides cathode materials, discuss the surface modification technologies regarding the manufacturing process and affordable cost, and finally propose the research perspectives for the EV market.