Sol-gel synthesis of multiwalled carbon nanotube-LiMn₂O₄nanocomposites as cathode materials for Li-ion batteries

This study reports the development of multiwalled carbon nanotube (MWCNT)-LiMn2O4nanocomposites by a facile sol-gel method. The elemental compositions, surface morphologies and structures of the nanocomposites are characterized with a view to their use as cathode materials for Li-ion batteries. The results indicate that the nanocomposite consists of LiMn2O4nanoparticles containing undamaged MWCNTs. The nanocomposites show high cycle performance with a remarkable capacity retention of 99% after 20 cycles, compared with LiMn2O4nanoparticles with a 9% loss of the initial capacity after 20 cycles. Measurements of a.c. impedance show that the charge-transfer resistance of the nanocomposites is much lower than that of spinel LiMn2O4. A cyclic voltammetry study further confirms higher reversibility of the nanocomposites compared with LiMn2O4particles. The enhanced electrochemical performance of the nanocomposites is attributed to the formation of conductive networks by MWCNTs that act as intra-electrode wires, thereby facilitating charge-transfer among the spinel LiMn2O4particles.