Influence of carbon coating on the performance of a LiMn0.5Ni0.5O2 cathode

The effects of coating alpha-NaFeO2-structured LiMn0.5M0.5O2 cathode materials with carbon particles has been investigated. The coated cathodes exhibit average discharge capacities of 108, 101 and 87 mAh/g at current densities of 0.25, 0.50 and 1.0 mA/cm(2), respectively, when cycled between 2.75 and 4.25 V, versus capacities of 88, 82 and 69 mAh/g for the uncoated cathodes cycled under the same conditions. The carbon coatings are shown to suppress the capacity fade observed in the uncoated cells by increasing the electronic conductivity and reducing cell polarization, thus preventing the evolution of oxygen from the cathodes. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.