Capacity Fading Mechanisms in Ni-Rich Single-Crystal NCM Cathodes

A series of single-crystal, Ni-rich Li[NixCoyMn1–x–y]O2 (NCM) cathodes (x = 0.7, 0.8, and 0.9) with particle diameters ?3 ?m are systematically compared polycrystalline corresponding Ni contents. Despite their high resistance to microcracking, the electrochemical performances single-crystal NCM cathodes, in terms capacity cycling stability, inferior those cathodes. In situ XRD TEM analyses reveal that lithium concentrations become spatially inhomogeneous during cycling; this phenomenon is exacerbated by C rates contents, resulting coexistence phases widely different unit cell dimensions within a single cathode particle. This two induces nonuniform stress generates structural defects, impairing diffusion ions and, eventually, leading rapid fading.