The role of particle size on the electrochemical properties at 25 and at 55 °C of the LiCr0.2Ni0.4Mn1.4O4 spinel as 5 V-cathode materials for lithium-ion batteries

The role of the particle size on the electrochemical properties at 25 and at 55 degrees C of the LiCr0.2Ni0.4Mn1.4O4 spinel synthesized by combustion method has been determined. Samples with different particle size were obtained by heating the raw spinel from 700 to 1100 degrees C, for 1 h in air. X-ray diffraction patterns revealed that all the prepared materials are single-phase spinels. The main effect of the thermal treatment is the remarkable increase of the particles size from similar to 60 to similar to 3000 nm as determined by transmission electron microscopy. The electrochemical properties were determined at high discharge currents (1C rate) in two-electrode Li-cells. At 25 and at 55 degrees C. in spite of the great differences in particle size, the discharge capacity drained by all samples is similar (Q(dch) approximate to 135 mAh g(-1)). Instead, the cycling performances strongly change with the particle size. The spinels with Phi > 500 nm show better cycling stability at 25 and at 55 degrees C than those with Phi < 500 nm. The samples heated at 1000 and 1100 degrees C, with high potential (E approximate to 4.7 V), elevate capacity (Q approximate to 135 mAh g(-1)), and remarkable cycling performances (capacity retention after 250 cycles >96%) are very attractive materials as 5V-cathodes for high-energy Li-ion batteries. (C) 2009 Elsevier Ltd. All rights reserved.