Perpustakaan Digital ITB

Global warming drives the development of sustainable energy storage technologies, with lithium-ion batteries (LIBs) being promising due to their high energy density and long cycle life. Li-rich cathode materials are considered promising for next-generation LIBs due to their high specific capacity enabled by combined cationic and anionic redox processes. However, their practical application is limited by capacity fading, voltage decay, and poor rate capability. Surface modification using metal fluoride coatings offers a potential strategy to mitigate these limitations. This study investigates the effects of AlF3, LaF3, and AlF3/LaF3 surface coatings on the structural, morphological, and electrochemical properties of Li-rich (Li1.2Ni0.13Co0.13Mn0.54O2) cathodes, aiming to determine the most effective coating configuration for improving electrochemical performance. The Li-rich cathode material was synthesized using a sol–gel method followed by calcination and annealing under an O2 atmosphere. AlF3, LaF3, and AlF3/LaF3 coatings were subsequently applied using a hydrothermal method followed by heat treatment under an N2 atmosphere. The synthesized materials were characterized using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and high-resolution transmission electron microscopy (HR-TEM). The materials were fabricated into cathodes and assembled into lithium half-cells using lithium metal as the counter and reference electrode and 1 M LiPF6 in EC/DMC/EMC (1:1:1, v/v/v) with 1 wt% LiDFOB as the electrolyte. Electrochemical performance was evaluated using electrochemical impedance spectroscopy (EIS), galvanostatic charge–discharge, cycling, and rate capability tests within a voltage range of 2.0-4.8 V. The results confirmed the formation of the Li-rich phase with an ordered layered structure, while the coating process did not significantly alter the bulk crystal structure or particle morphology. EDS confirmed the presence and distribution of Al and La on the coated cathode surfaces, while HR-TEM revealed nanoscale coating layers with thicknesses of approximately 3-7 nm. The AlF3/LaF3 coating exhibited the lowest charge transfer resistance of 16.36 ? and the highest Li+ diffusion coefficient of 4.5301 × 10?18 cm2/s, indicating improved interfacial electrochemical kinetics. Although the fluoride coatings slightly reduced the initial discharge capacity due to their electrochemically inactive nature, they substantially improved cycling and rate performance. The Li-rich@AlF3/LaF3 cathode achieved 90.67% capacity retention after 300 cycles at 0.5C, delivered 92.99 mAh/g at 5C, and exhibited the lowest voltage decay of 0.84 V. Overall, the dual AlF3/LaF3 coating provided the best electrochemical performance among the investigated coating configurations.