Spray deposition of LiMn₂O₄ nanoparticle-decorated multiwalled carbon nanotube films as cathode material for lithium-ion batteries

We prepared LiMn₂O₄ nanoparticle-decorated multiwalled carbon nanotube (MWCNT) films as a cathode electrode for lithium-ion batteries using a spray-deposition method. The surface morphologies and structures of the films were characterized using scanning electron microscopy and X-ray diffraction analysis. The results revealed that fairly homogeneous spinel LiMn₂O₄ nanopowder-based films with the grain size of 20-50 nm were successfully formed on the surface of the MWCNTs. Cyclic voltammetry confirmed the presence of typical spinel LiMn₂O ₄ structure on the MWCNTs with showing stronger oxidative peaks of better reversibility as compared to a pure LiMn₂O₄ electrode. The spray-deposited LiMn₂O₄-decorated MWCNT film was also found to have a higher discharge capacity (97.2 mAh/g) than the as-deposited LiMn₂O₄ film (75.2 mAh/g) as well as excellent cycling stability. These characteristics are due to the fact that MWCNTs provide the cathode with multiple electron tunneling pathways and a mechanically strong framework.