Effects on electrochemical performances for host material caused by structure change of modifying material

Abstract

High ionic conductive lithium niobium oxides were selected as the modifying material to investigate the effects on the electrochemical performances for host material LiNi_1/3Co_1/3Mn_1/3O₂ caused by the structure change of the modifying material at various calcination temperatures and modifying amounts. X-ray diffraction (XRD) studies revealed that the structure of the modifying material was single LiNbO₃ phase after being calcined at 500 °C and changed to LiNbO₃–Li₃NbO₄ mixture phases at 600 and 700 °C, and further changed to single Li₃NbO₄ phase at 800 °C. Electrochemical tests displayed that both LiNbO₃ and Li₃NbO₄ phases of modifying material could contribute to the improvement of the cycle performances for the host material, but the improvement degree of Li₃NbO₄ phase was more evident. The cycle performances and high rate performances of the modified host material (calcined at 700 °C) electrodes were improved with the right modifying amount.