Theoretical Investigation of Degradation Mechanisms in High Voltage Na-ion Battery Cathodes

This project explores the degradation mechanisms in high-voltage sodium-ion (Na-ion) battery cathodes using theoretical methods. Na-ion batteries are a promising alternative to lithium-ion (Li-ion) batteries due to their cost-efficiency, sustainability, and the abundance of sodium. A key focus is the cathode, which makes up around 40% of the battery cost. By utilizing sustainable elements such as sodium and doping cheap transition metals (TMs) like manganese (Mn), Titanium (Ti) in Nickel (Ni), there is potential for significant cost reductions and environmental benefits. However, the redox behavior of these TM ions during battery cycling are not well understood, which is critical for achieving high energy density at elevated voltages. At high voltages, complex TM-oxygen interactions and oxygen redox can lead to oxygen loss and hence battery degradation. The challenge lies in determining the charge compensation mechanism because of overlapping TM-O orbitals and high covalency. 

This research aims to reveal the oxidation state changes in various Transition metal ion doped Ni rich Na-ion cathodes to ensure stability and capacity retention at high voltages. State-of-the-art Dynamical Mean-Field Theory (DMFT) calculations in conjunction with Density Functional Theory (DFT) will monitor the oxidation state changes during charging/discharging, providing a comprehensive understanding of the redox behavior and charge compensation mechanisms, hence providing an understanding of the degradation mechanisms. All the results will be correlated to experimental X ray absorption spectra based determination of charge states, and gas spectrometry based determination of O loss by our experimental colleagues. Our holistic understanding of the Na ion based degradation mechanisms  will be pivotal in guiding the design of more efficient and stable Na-ion cathode materials for grid storage options.

Key objectives and potential impact:

1. Understanding of O redox behaviour in Na based cathodes
2. Understanding of structural reconstruction through many body method development
3. Design of futuristic and cheap Na based cathode with high capacity,
4. Method and code to carry out many body structural relaxation

Any specific requirements for candidates: 

• Computational Skills required
• Basic coding in either FORTRAN, C, or Python
• Basic Understanding of Solid State Physics
• Quantum Mechanics, or Quantum Chemistry

Diversity statement

Our research community thrives on the diversity of students and staff which helps to make the University of Dundee a UK university of choice for postgraduate research.  We welcome applications from all talented individuals and are committed to widening access to those who have the ability and potential to benefit from higher education.