Influence of realistic load profiles on Lithium-Ion Cell Degradation

Kurzfassung

The degradation of batteries is dependent of the use in their particular application. The loss of capacity because of cycling correlates in some degree to utilization in consumer electronic devices. But the utilization in battery electric vehicles (BEV) or stationary applications like frequency regulation for grid stability imply a different strain for the used battery cells. For example a BEV (with recuperation) in urban traffic accelerates and decelerates periodically. This represents a special stress influence due to the alternating load between discharge and charge. In this study the effects of BEV utilization on lifetime performance of commercial Lithium-Ion cells were investigated. Therefor single cells were stressed in a test bench with different realistic load profiles according to standardized driving cycles. The used data were obtained from a Modelica simulation of the city car Hotzenblitz which is a limited-lot production vehicle. The actual vehicle is equipped with a 12kW electric traction drive and reaches a maximum speed of 112km/h. For the simulation an increased traction motor of 30 kW was assumed, so the applied driving cycles could be fulfilled. For the tests the Common Artemis Driving Cycle (CADC) Urban were compared with the CADC Road to face the SOH loss due to frequent acceleration and deceleration in urban traffic to high kilometric performance in overland traffic. The New European Driving Cycle (NEDC) was used as reference.