M[sub 3](PO[sub 4])[sub 2]-Nanoparticle-Coated LiCoO[sub 2] vs LiCo[sub 0.96]M[sub 0.04]O[sub 2](M=Mg and Zn) on Electrochemical and Storage Characteristics

The electrochemical cycling and storage characteristics of and nanoparticle-coated cathode materials were compared at room temperature and between 3 and . The doped cathodes showed degraded electrochemical performance at room temperature compared to the uncoated cathode. The first discharge capacities of the uncoated and the doped cathodes were 186 and , respectively. The doped cathodes showed after 30 cycles, while the uncoated cathode showed after 50 cycles at a rate. and -coated showed discharge capacities of 179 and , respectively, and hadsignificantly improved capacity retention, showing 133 and , respectively, after 50 cycles. After storage at , in the electrolytes using charged electrodes, the doped cathodes showed both greatly decreased side reactions with the electrolytes and formation of and phases from Li and Co dissolution. However, the coated cathodes did not show either structural transformation into the and phases or side reactions with the electrolytes.