Effective Strategies for Improving the Cycle Life of Ni-Rich LiNixMnyCozO2 Cathodes for Lithium-Ion Batteries

Abstract

Lithium ion battery (LIB) is considered the most promising energy storage system for applications in electrical vehicles (EVs). However, the large-scale market penetration of EVs has been impeded by several challenges, particularly the limited energy density, high cost and safety concern of cathodes in LIB. Conventional layered oxide LiCoO2 (LCO) has been widely used in LIBs developed for consumer electronics, but the high cost of cobalt, low lithium utilization (~0.5 Li) has limited its application for EVs. To increase the driving range of EVs to over 300 miles at a single charge and promote the massive market penetration of EVs, low-cost electrode materials with high tap density, high-energy density, good rate capability, and long-term cycle life must be developed. Recently, Ni-rich layered structure cathode materials LiNixMnyCozO2 (NMC, x ≥ 0.6) have been receiving much attention as one of the most promising cathode materials for large scale applications owing to their high discharge capacity (200~220 mAh g-1) and energy density (~800 Wh kg-1) as compared to traditional LiCoO2 (~570 Wh kg-1). However, several technical challenges still exist with these Ni-rich NMCs due to their structural/interfacial instability and poor thermal stability. In this presentation, we will discuss several effective approaches, including lattice doping, grain boundary engineering, and use of novel electrolytes that enhance the structural/interfacial stability of Ni-rich NMC cathodes and significantly improved their long-term cycle life.