Extracting redox orbitals in nickel-rich lithium battery cathodes using X-ray Compton scattering

Abstract

The transition from fossil fuels to renewable energy sources is one of the most critical challenges facing humanity today. A key aspect of this shift in energy sources is the move towards electric vehicles; 200 million electric vehicles are expected to be on the road by 2030. However, the need for long-lasting and sustainable batteries as well as new battery designs based on a comprehensive, atomic-level understanding of battery operations remains a significant challenge in this transition. In this regard, nickel-rich lithium battery cathodes are at the forefront of energy storage research due to their high energy density and promising applications in electric vehicles and renewable energy systems. Thus, this dissertation explores the electronic structures of LiNiO2 and tungsten (W)-doped lithium nickel oxide (LNO) cathodes using a combination of X-ray Compton scattering and firstprinciples density functional theory (DFT) calculations.

One of the key findings of this study is that oxygen orbitals play a crucial role in the redox activity of LiNiO2. This challenges the traditional view that nickel ions solely dictate charge transfer. Moreover, this study provides a detailed analysis of momentum density using an advanced Compton scattering technique, revealing that oxygen involvement significantly influences charge transfer and energy density. Furthermore, W doping was found to improve the structural integrity of LNO by reducing cation mixing, suppressing phase transitions, and improving electronic conductivity. These modifications prolong cycle life and improve the overall performance of lithium-ion batteries.

This dissertation demonstrates the potential of X-ray Compton scattering as a powerful tool for characterizing cathode materials at the quantum level. In addition, the work provides valuable insights into the electronic interactions that influence battery efficiency. The findings presented in this dissertation contribute to the ongoing advancement of lithium-ion battery technology, thereby paving the way for more stable and efficient energy storage solutions. By improving the understanding of redox mechanisms and doping strategies, this research supports the development of next-generation battery materials essential for creating a sustainable energy future.