Effect of Atomic Layer Fluorination on the Structural and Electrochemical Properties of LiNi_0.5Mn_1.5O₄ High Voltage Electrodes

A surge in the need for energy storage with high energy density is evident, especially given the rise of electric vehicles and hand-held electronic devices. This growing demand underscores the importance of innovating in battery technology. In this realm, lithium-ion batteries (LIBs) stand out for their impressive energy density. Notably, the spinel LiNi_0.5Mn_1.5O₄ (LNMO) material has caught the attention of LIBs due to its commendable electrochemical characteristics. This study focuses on the surface modification of disordered LNMO using the Atomic Layer Fluorination (ALF) method and investigates the influence of atomic fluorine on the interface between the LNMO and the electrolyte. Various characterization techniques, including X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy-Scanning Auger Microscopy (AES-SAM), Scanning Electron Microscopy (SEM), Nuclear Magnetic Resonance (NMR), and Electron Paramagnetic Resonance (EPR), are used to analyze the modified LNMO samples and understand the surface mechanism. Electrochemical tests reveal significant improvements in the cycling stability of fluorinated LNMO, while the rate capacity remains comparable to that of the pristine LNMO.