Capacity fading mechanism of large scale Li4Ti5O12/LiCoO2 battery

Lithium titanate battery suffers from high capacity fade for elevated temperature operation. In order to gain new insights into the underlying degradation mechanism of this problem, Li
4
Ti
5
O
12
/LiCoO
2
battery with 8Ah capacity was assembled and its storage and cycling performance at 60°C were investigated. Electrochemical impedance spectroscopy (EIS) of cells during cycling were measured with two-electrode and three-electrode 8Ah pouch cells. XRD, SEM and half-cell characterization of the cycled cells were analyzed. Accelerating Rate Calorimeter was used to monitor the battery surface temperature during cycling at 60° and 3C rate. The results showed that the capacity fade of this cell was mainly caused by degradation of LiCoO
2
cathode.