Material Designs of Ni-Rich Cathodes for Practical Applications in High Energy Li-Ion Batteries

Abstract

The increasing demands for the mobile electronics, electric vehicles and electrical energy storage systems necessitate the state-of-the-art lithium ion battery with high energy/power density.1-3 To meet these demands, layered nickel-rich cathode materials have been considered as the most promising candidate among a variety of the cathode materials owing to their high reversible capacity.4-7 However, the inherent hurdles of the nickel-rich cathodes, which is the phase transition from the layered to the rock-salt structure, the existence of residual lithium compounds and morphological evolutions significantly deteriorated the battery performance.8-11 Hence, to date, a variety of strategies such as the morphological controls12-14, surface coating15-33 and doping approaches34-41 have been introduced into the nickel-rich cathode materials. Although these strategies considerably enhanced the electrochemical performance, the synthetic method of the cathode materials is complex due to the usage of volatizing and toxic solvent. More importantly, intrinsic high residual lithium compounds at the cathode surfaces could not be eliminated by such approaches, which causes battery safety issues. Furthermore, it should be emphasized that the nickel-rich cathode materials retained the limited available electrode density with increasing the nickel content in the cathode materials, significantly hindering the increase of the volumetric energy density.42 In this regard, it is essential to consider the issues related to the improvement of electrode density for the commercial uses, as well as the structural and chemical instability of the material itself. Accordingly, herein, I have covered the development of the nickel-rich cathode materials via the morphological controls and surface engineering with simple synthetic method, and finally reviewed a comprehensive study about intrinsic hurdles of the polycrystalline Ni-rich cathode materials at the high-density electrode for high energy LIBs.