Microwave-assisted hydrothermal synthesis of electrochemically active nano-sized Li₂MnO₃ dispersed on carbon nanotube network for lithium ion batteries

Electrochemically active Li₂MnO₃ nanoparticle dispersed on carbon nanotube (CNT) network has been successfully synthesized by microwave-assisted hydrothermal (MAH) process. To the best of our knowledge, this is the first report showing the formation of Li₂MnO₃ nanoparticle on CNT network using MnO₂-coated CNT composite. Appearance of superlattice peak in X-ray diffraction (XRD) pattern and Raman-active modes near the lower wavelength region of Raman spectra reveals the structure transition from spinel LiMn₂O₄ to layered-type Li₂MnO₃ phase. The X-ray absorption near edge spectra (XANES) shows increase in average oxidation state of Mn ion from 3.5+ to 4+, and Mn-O and Mn-Mn peak intensity variations observed from extended X-ray absorption fine structure (EXAFS) are well evidenced for the formation of ordered Li₂MnO₃ structure. Electrochemical performance of Li₂MnO₃ nanocomposite electrode material prepared from higher LiOH concentration shows much higher capacity than spinel component alone. This synthetic strategy opens a new way for effective synthesis of electrochemically active Li₂MnO₃ on CNT network, making it suitable for advanced lithium ion battery.