Preparation and Rate Capability of Carbon Coated LiNi1/3Co1/3Mn1/3O2as Cathode Material in Lithium Ion Batteries

LiNi_1/3Co_1/3Mn_1/3O₂ (NCM) is regarded as a promising material for next-generation lithium ion batteries due to the high capacity, but its practical applications are limited by the poor electronic conductivity. Here, a one-step method is used to prepare carbon coated LiNi_1/3Co_1/3Mn_1/3O₂ (NCM/C) by applying active carbon as reaction matrix. TEM shows LiNi_1/3Co_1/3Mn_1/3O₂ particles are homogeneously coated by carbon with a thickness about 10 nm. NCM/C delivers the discharge capacity of 191.2 mAh g^-1 at 0.5 C (85 mA g^-1) with a columbic efficiency of 91.1%. At 40 C (6800 mA g^-1), the discharge capacity of NCM/C is 54.6 mAh g^-1, whereas NCM prepared through sol-gel route only delivers 13.2 mAh g^-1. After 100 charge and discharge cycles at 1 C (170 mA g^-1) the capacity retention is 90.3% for NCM/C, whereas it is only 72.4% for NCM. The superior charge/discharge performance of NCM/C owes much to the carbon coating layer, which is not only helpful to increase the electronic conductivity but also contributive to inhibit the side reactions between LiNi_1/3Co_1/3Mn_1/3O₂ and the liquid electrolyte.