Enhancing Stability and Performance in Sodium-Ion Batteries: A Density Functional Theory Study of Titanium Doping and Water Intercalation Effects on NaFePO4 and NaCoO2 Cathodes

Abstract

Sodium-ion Batteries (NIBs) are considered a promising alternative to the wide-spread lithium-ion batteries (LIB) due to their natural abundance, low cost, and similar electrochemical property to lithium. Owing to their low cost and high theoretical capacity, Layered transition metal oxides (NaxTMO2) and Polyanion are scrutinized as promising Na-ion cathode materials. Although lots of improvement has been studied over the past couple of decades to improve the cycling stability, rate capability, and specific capacity of NaxTMO2, the lack of structural stability of this type of layered oxides and Polyanion against water still hinders its practicability due to its unstable nature in air atmosphere. In this study, the theoretical modeling of layered oxides with the proper transition metal ion substitution in the presence of water molecules were proposed. This study utilizes the density functional theory (DFT) to assess the structure of the cathode materials and compare them in terms of characteristics that make them viable for use. Surface adsorption and reaction with H2O and CO2 in air have been modeled on the surficial crystalline structure. Co and Ti substituted in NaxTMO2 and Polyanion cathodes.

Date of Award	18 Dec 2023
Original language	American English
Supervisor	Ali Alhammadi (Supervisor)