Cycle Life Research Of Lithium-ion Power Battery For Electric Vehicle

New measures have been taken in automobile industry because of the increase of energy sources crisis and environmental pollution. Electric vehicles (including fuel cell electric vehicles (FCEV), pure electric vehicles (EV) and hybrid electric vehicles (HEV)) are the research focuses. As the power source, high power and high energy battery pack is one of the key components of the electric vehicles, and the performance of the batteries have important effect on the prospect of the electric vehicles. Lithium-ion batteries are considered as the most promising batteries with much of advantages like high voltage, high specific energy , good cycle performance and no pollution to circumstances, etc. At the same time, the technologies of the test, evaluation for lithium-ion battery have been developing quickly, and are applied intensively. Cycle life which is an important characteristic of the battery is the one of the key factors of electric vehicles'industrialization.In this paper, the cycle performances of 15Ah and 17Ah lithium-ion batteries for HEV were tested under common test condition and work test condition in different temperature environment. The conclusions obtained from the study are as follows:1. The consistency of the lithium-ion power batteries was analyzed by tests under simple simulation work condition, and electric performances such as standard capacity were evaluated by common charge-discharge cycles. The results exhibits that the consistency of the performances of the lithium-ion power batteries tested are good, and are applicable for the cycle life tests.2. The cycle performance of the lithium-ion power batteries were studied by standard capacity tests and simulation work condition tests, and were compared by tests under different environmental temperature. High temperature has much more effects on the cycle performance. The capacity attenuates quickly at 55℃. In low temperature environment, the cycle performance is correlated with the conductance of electrolyte and the kinds of actived materials.3. The simulation results exhibit that the approaches of charge-discharge is not the only factor effect on cycle performance, which is related with electrochemical reacts happen inside the lithium-ion battery.