A simple mechano-thermal coating process for improved lithium battery cathode materials

摘要

A simple, economical and convenient mechano-thermal coating procedure for the production of LiCoO_2 with improved cycling performance is described. The coating material was pre-formed nanoparticulate fumed silica. TEM studies with a 1.0wt.% silica-coated cathode suggested that the silica species partially diffused into the bulk of the cathode material. XRD studies showed a diminished lattice parameter c upon coating, indicating that a substitutional compound of the LiSi_yCo_(1-y)O_(2+0.5y) type might have formed upon calcination. SEM images, R-factor values from XRD studies and electrochemical studies showed that a coating level of 1.0wt.% gave an optimal performance in capacity and cyclability. SEM images showed that above this level, the excess silica formed spherules, which got glued to the coated cathode particles. Galvanostatic cycling studies showed that at a coating level of 1.0 wt.%, cyclability improved three and nine times for two commercial LiCoO_2 samples.