Coating of licoo2 cathode active compounds with lif and investigation of electrochemical and quantum properties by DFT method

In this thesis, the electrochemical performance enhancement of LCO, a widely used cathode active material in lithium-ion batteries, was investigated through surface coating and theoretical analysis based on Density Functional Theory (DFT). LCO was synthesized via three different methods: sol-gel, hydrothermal, and solid-state, and the results were comparatively evaluated. Among these, the sol-gel method demonstrated the highest specific capacity and was selected as the primary synthesis route for subsequent studies. To improve surface stability and electrochemical behavior, LiF (lithium fluoride) coatings at different ratios (notably 2% and 7%) were applied to the LCO surface. The coated samples were tested under various current rates, and it was found that the 7% LiF-coated electrode achieved a capacity of 214 mAh/g at 0,1 C, indicating a significant enhancement in performance due to improved ionic conductivity and surface protection provided by the LiF layer. Furthermore, DFT-based theoretical calculations revealed that the LiF coating formed a strong adsorption interaction with the LCOsurface, reducing the Gibbs free energy of the system and contributing to thermodynamic stability. The adsorption energy, enthalpy, entropy, and optimized molecular geometries confirmed the favorable interaction between LiF and the LCO surface. This study demonstrates that integrating surface modification techniques with quantum-level theoretical analysis offers a comprehensive approach to improving the performance and stability of cathode materials for advanced lithium-ion battery applications.