The surface Al2O3 coating and bulk Zr doping drastically improve the voltage fade and cycling stability of Li(Ni0.8Mn0.1Co0.1)O2 cathode materials

Abstract

One of the major hurdles of the high Ni content layered oxides (NLOs) in making lithium-ion batteries is their low cycling stability, especially for the NLOs with Ni content ≥ 60%; such NLOs have clear drawbacks including severely fading capacities and impedance increase during cycling. Two promising surface and bulk modifications of such NLOs to alleviate the drawbacks are: (1) the surface coatings by electrochemically inert inorganic compounds and/or (2) the lattice doping by cations. In this work, isopropanol alcoholysis has been used to achieve uniform surface Al2O3 coating on one of NLOs: LiNi0.8Co0.1Mn0.1O2 (NCM811). The bulk Zr4+ doping and surface Al2O3 coating have been realized after annealing at ≥ 800 °C, which enhance the specific capacity of discharge and cycling life of the NCM@Al2O3 +Zr active material, and effectively suppress the voltage attenuation during cycling process. The main finding of this work is the enhanced cycling stability and the diminished impedance of the coated/doped NCM811, being provided by a synergetic effect of the Al2O3 coating and the Zr4+ doping.