Annealing-Temperature Effect on Various Cutoff-Voltage Electrochemical Performances in AlPO[sub 4]-Nanoparticle-Coated LiCoO[sub 2]

The electrochemical properties of -coated cathodes were found to be superior to those of bare cathodes at various charge-cutoff voltages (4.3, 4.6, and 4.8 V), and depended on the annealing temperature. The -coated cathodes annealed at 600 and 700°C retained a discharge capacity of ∼150 mAh/g even with a 4.8 V charge-cutoff voltage (after 46 cycles at 1 mA/g). The bare cathode showed zero capacity retention at the same condition after only 20 cycles. The enhanced electrochemical performance and rate capability in the coated cathodes were attributed to the inhibition of structural degradation during cycling. The -nanoparticle coating layer on the effectively suppressed cobalt dissolution and a nonuniform distribution of local strain in the cathode.