Sol-gel synthesis of multiwalled carbon nanotube-LiMn₂O₄ nanocomposites as cathode materials for Li-ion batteries

This study reports the development of multiwalled carbon nanotube (MWCNT)-LiMn₂O₄ nanocomposites 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 LiMn₂O₄ nanoparticles containing undamaged MWCNTs. The nanocomposites show high cycle performance with a remarkable capacity retention of 99% after 20 cycles, compared with LiMn₂O₄ nanoparticles 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 LiMn₂O₄ particles. 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 LiMn₂O₄ particles.