Common use of Thermal stability Clause in Contracts

Thermal stability. The Accelerated Rate Calorimeter EV ARC from THT, see Figure 8, will be used for the thermal abuse tests, in order to determine the temperature at which the cell becomes unsafe. The tests will be performed on cells previously fully charged, according to a standard charging procedure defined by the Partner in charge of the cell manufacturing. Figure 8: Photographs of the calorimeters used at CEA to perform thermal runaway tests Thermal runaway tests will be performed in a pseudo-adiabatic calorimeter, following the “Heat-Wait-Seek” protocol: from an ambient temperature called start temperature, the temperature is raised for a given temperature step, then stabilized until an exothermal reaction of the cell is detected in less than 30 minutes. If not, a new temperature step is done. An exothermal reaction is considered when self-heating is higher than the temperature rate sensitivity measured at skin level. When detected, this temperature level is recorded and called the onset temperature. Then, the temperature keeps on rising until the end temperature threshold is reached, or if the maximum temperature rise criterion called end temperature rate is reached. The Figure 9 below gives an illustration of the process: The setup proposed for ASTRABAT project is:  Start temperature: 30°C  Temperature step: 5°C  Temperature rate sensitivity: >0.02°C/min. = thermal runaway  End temperature: 200°C  test stop  End temperature rate: 3°C/min.  test stop Annex: EUCAR Hazard levels