ELECTROTHERMAL MODELING OF POLYMER LITHIUM BATTERIES FOR STARTING PERIOD AND PULSE POWER

Since power capabilities of solid polymer lithium batteries can only be delivered above 60 degrees C, the thermal management in electric-vehicle applications has to be carefully considered. Electro-thermal modelling of a thermally insulated 200 kg battery was performed, and electrochemical data were obtained from laboratory cell impedance measurements at 20 and 80 degrees C. Starting at 20 degrees C as initial working temperature, the battery reaches 40 degrees C after 150 s of discharge in a 0.5 Omega resistance. At 40 degrees C, the useful peak power is 20 kW. The energy expense for heating the battery from 20 to 40 degrees C is 1.4 kWh, corresponding to 6% of the energy available in the battery. After a stand-by period of 24 h, the temperature decreases from 80 to 50 degrees C, allowing efficient starting conditions.