Practical Codoping Strategy for Ni-Rich Cathode Materials

Although Ni-rich layered oxides represent useful candidates for use as lithium-ion battery cathodes, their intrinsic microstructural instabilities limit their practical usage. Herein, a multistage codoping strategy employing low-valence Ti and high-valence Ta is proposed for optimizing their spatial distributions. Initially, Ti is incorporated during the coprecipitation of the [Ni0.90Co0.05Mn0.05](OH)2 precursor, ensuring homogeneous structural doping of Ti within the cathode material. Ta is subsequently introduced during calcination, promoting its grain boundary segregation to refine the primary particle morphology. As a result, the two dopants are distributed in a manner that enhances their respective functionalities. The proposed strategy improves not only the battery cycle life, but also its thermal stability, which has previously been considered as key limitations of Ni-rich cathodes. This spatially optimized codoping strategy offers a rational design principle for durable and practical Ni-rich cathodes for use in next-generation lithium-ion batteries.