Stabilized Nickel Rich Layered Oxide Electrodes for High Performance Lithium-Ion Batteries

The rapid evolution of battery technology necessitates the exploration of innovative strategies to improve the electrochemical performance and lifespan of cathode materials in lithium-ion batteries. Nickel-rich layered transition metal oxides have emerged as promising candidates due to their high energy densities. However, practical application is hindered by issues such as accelerated degradation and capacity fade during cycling, attributed to structural changes and the reactivity of Ni4+ ions. This doctoral thesis focuses on optimizing coating strategies to overcome challenges associated with Ni-rich cathode materials in lithium-ion batteries. It highlights the significance of surface modifications in minimizing side reactions, boosting stability, and enhancing conductivity. Various coating techniques, including atomic layer deposition, physical vapor deposition, and wet chemistry approaches, are explored for their ability to create tailored conformal coatings. The research reveals the impact of atomic layer deposition coating characteristics, such as porosity, lithium diffusivity, chemical stability, and thickness, on the electrochemical performance of Ni-rich cathode materials. Experimental analyses and electrochemical experiments are conducted to develop and fine-tune coatings like Li fluoride, metal oxide, Li-containing metal oxide, and hybrid organic-inorganic films. These coatings aim to boost interfacial stability, suppress parasitic reactions, and improve lithium-ion diffusion of positive electrode materials. Key findings demonstrate that coatings with lithium and a 3D structure, coupled with increased porosity, exhibit superior performance in facilitating lithium-ion diffusion and mitigating capacity fade. Molecular layer deposition emerges as a promising technique for creating flexible coatings capable of accommodating volume changes in the electrode during cycling, thus enhancing battery longevity. Overall, this thesis introduces coating strategies for Ni-rich cathode materials for lithium-ion batteries, providing insights into revolutionary solutions for battery performance and next-generation energy storage systems. The research underscores the critical role of surface modifications in enhancing the efficiency, stability, and longevity of lithium-ion batteries, thereby addressing key challenges in transitioning to sustainable energy solutions