Significant Improvement of LiNi[sub 0.8]Co[sub 0.15]Al[sub 0.05]O[sub 2] Cathodes at 60°C by SiO[sub 2] Dry Coating for Li-Ion Batteries

The cycling performance of a cathode at was substantially improved by direct dry coating. The -coated cathode was obtained from firing of the mixture consisting of nanoparticles and the cathode powders with a weight ratio of 99:1 at for 5 h. The first discharge capacity of the coated cathode was 172 mAh/g, whereas the uncoated one showed 182 mAh/g at . However, the coulombic efficiency of the coated sample was 95%, which was 2% higher than that of the uncoated sample. Moreover, the discharge capacities of the coated cathode at was about 2.5 times larger than those of the uncoated sample at rates of 0.5 and 1C, showing 146 and 109 mA/g, respectively. This capacity improvement at is related to the fact that the highly distributed Si element near the surface, as a type of solid solution with , diminishes the side reactions of the cathode and electrolyte at .