Safety influences of the Al and Ti elements modified LiCoO2 materials on LiCoO2/graphite batteries under the abusive conditions

Abstract

Under the abusive conditions, it is demonstrated that the thermal stability of LiCoO2 and the safety of LiCoO2/graphite batteries are improved by doping and coating Al and Ti elements into the bulk structure and surface of LiCoO2. The trickle charge and the differential scanning calorimeter (DSC) results show that after coating Al and Ti oxides on the doped LiCoO2 with 2000 ppm Al, the exothermic peak shifts to a higher temperature and the exotherm decreases, resulting in the increase of the thermal stability of LiCoO2. In addition, compared to the LiCoO2 without Al doping, it is also indicated that the thermal stability of LiCoO2 can be enhanced by doping Al, the exothermic peak of the LiCoO2 with Al doping amount of 10000 ppm is up to 250 °C. Under the abusive testing conditions including thermal shock and overcharge, the safety evaluation results of pouch polymer LiCoO2/graphite batteries are in good agreement with the trickle charge and DSC results. These results reveal that the thermal stability of LiCoO2 can be used as an indicator to evaluate the safety characteristics of LiCoO2/graphite batteries, and especially the introduction of Al and Ti into LiCoO2 can effectively improve the safety of LiCoO2/graphite batteries under the abusive conditions.