The crucial ageing behaviour was investigated in GHOST for 23 Ah LTO cells. The selected cells are studied for both the degradation aspects as the cycle life and calendar life. A total of 69 cells are tested with varying ageing stress factors to understand the degradation scenario. VUB and IKERLAN have taken care of the cycling and calendar life campaigns, respectively. The 2-year long test campaign has cycled cells up to 12000 times and stored cells for 1.5 years gathering the capacity fade information. The developed knowledge is analysed to identify the crucial stress factors which have been utilised to parameterise a lifetime model. A capacity fade model is constructed based on a semi-empirical methodology that is validated against real-life dynamic cycling resulting in a 0.45% root-mean-square error. This proves that the model can project the capacity fade of the studied cell with high accuracy.

The developed accurate lifetime model can be used to predict the state of health or remaining useful life of the battery cell which can provide useful information to the second-life investigation.

GHOST lifetime model development overview.