Single crystal Ni-rich NMC cathode materials for lithium-ion batteries with ultra-high volumetric energy density†
Nickel-rich layered transition metal oxides (LiNixMnyCo1−x−yO2 (x ≥ 0.6), Ni-rich NMCs) have been under intense investigation as high-energy density and low-cost positive electrode materials for Li-ion batteries. However, insufficient cyclic and thermal stability as well as low tap density hinder broad commercial application of commonly used polycrystalline Ni-rich NMCs. Here, we report on single crystal Ni-rich NMCs with improved cycling stability and ultra-high tap density up to 3.0 g cm−3 coupled with high discharge capacity, resulting in enhanced volumetric energy density of prepared electrodes up to 2680 W h L−1. Record tap density is achieved due to the formation of single crystal particles with spherical-like shapes through adjustment of the lithium chemical potential by using K2SO4 as a solvent during the single crystal growth. The designed single crystal NMC622 and NMC811 cathode materials are promising for applications in batteries with high specific energy and long-term cycling life.