Single crystal Ni-rich NMC cathode materials for lithium-ion batteries with ultra-high volumetric energy density

Abstract

Nickel-rich layered transition metal oxides (LiNi_xMn_yCo_1−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.