Electrochemical Properties of LiNi_0.8Co_0.16Al_0.04O₂ and Surface Modification
with Co₃(PO4)₂ as Cathode Materials for Lithium Battery

摘要

The electrochemical and thermal stability of LiNi0.8Co0.16Al0.04O2 were studied before and after Co3(PO4)2 coating. Different to conventional coating material such as ZrO2 or AlPO4, the coating layer was not detected clearly by TEM analysis, indicating that the Co3(PO4)2 nanoparticles effectively reacted with surface impurities such as Li2CO3. The coated sample showed similar capacity at a low C rate condition. However, the rate capability was significantly improved by the coating effect. It is associated with a decrease of impedance after coating because impedance can act as a major barrier for overall cell performances in high C rate cycling. In the DSC profile of the charged sample, exothermic peaks were shifted to high temperatures and heat generation was reduced after coating, indicating the thermal reaction between electrode and electrolyte was sucessfully suppressed by Co3(PO4)2 nanoparticle coating.