Development, Synthesis and Characterization of Advanced Low- Cobalt and High-Nickel Cathode Materials for Lithium-Ion Batteries

Abstract

This dissertation focuses on the improvement of structural and electrochemical stability of active materials for lithium-ion batteries. It explores the modification strategies to mitigate the issues related to Ni-rich cathode materials, along with the continuous production of cathode precursors using a slug flow reactor to improve the quality of the product. The First part of the dissertation examines the effect of substitution of cobalt with aluminum and iron on the electrochemical stability of Ni-rich lithium nickel cobalt manganese oxide (NCM) materials. This study investigates how Al and Fe doping work and how they impact the performance and stability of these materials. Both of these studies use three different amounts of Al and Fe to find the optimum amount of dopant for a better electrochemical performance. The results of this study are further used to suppress the formation of nickel oxide impurity phase during the high-temperature calcination. The second part explores methods to improve the structural stability of Ni-rich NCM cathode materials. A modified three-phase slug flow reactor is used to synthesize core-shell material by sequential addition of metal salts, where the core is high nickel and the shell has high manganese. The work studies the viability of a slug flow reactor to produce battery precursor materials with the modified design. The third part of the dissertation utilizes a single-crystal synthesis method to improve the cycling stability of Ni-rich cathodes. The study uses a simple high-temperature calcination process to synthesize a single-crystal structure. The reasons for improved stability of single-crystal materials are investigated along with the effect of the formation of impurities. A dual modification strategy is applied to further improve the coulombic efficiency of active material, where the material is doped with aluminum and synthesized as a single-crystal material. Finally, calculations and suggested reactor arrangements are provided for scale-up to produce kg-scale material using a slug flow reactor, along with the economic benefits of doping. The advancements presented in this work contribute to the ongoing development of durable and high-performance lithium-ion batteries