Chemical Characterization For Prediction Of TheBattery Calendar Life Of Electric Vehicle

Because of the high oil prices and serious environmental pollution, the high energy-efficient, less polluting electric vehicles have acctracted increasing attentions. Now, most of the developed countries and automobile manufacturers have put a great manpower, material and financial resources into electric vehicles. After basic research, breakthroughs in key technologies, product development and testing, it has come to small quantities of commercial production and practical application of the exploratory stage. In China, the research and development of electric vehicles is included in the national scientific and technological project early, the Ministry of Science and Technology has even more included electric car project in the national "863" on "Tenth Five-Year","Eleventh Five-Year" period. China makes clearer and detailed requirements on the development of electric vehicles in "Twelve Five-Year" plan.The first electric car was discoveried about180years ago, however, PHEV and EV are not real large-scale commercialization. The reliability and economy of electric vehicles was difficult to be evaluated, because that the battery’s life has not been investigated. Scientists from various countries and research institutions on this issue carried out in-depth research and built many models, but because of these analyzes are built on the basis of laboratory levels and ignored the vehicle structure design, control strategy design, real use condition, therefore they cannot be used to assess the real life of a production car.Based on this background, we firstly build a method to evaluate the calendar life of an EV made by BYD, then distinguish the influence between the circulation and storage, and evaluate the fade rate of the battery at different temperatures, and then analyze the environment, calculate the calendar life of the electric vehicles in Shenzhen typical weather. Then we evaluated the feasibility of quantitative analysis of the relationship of the battery’s SEI composition and battery attenuation by FTIR, At last we verified the calendar life assessment methods by actual vehicles, achieved good experimental results. The major findings of this dissertation are as following:(1) First we distinguish the influence between the circulation and storage, and evaluate the fade rate of the battery at different temperatures, then build a battery capacity fade model and then analyze the environment, calculate the calendar life of the electric vehicles in Shenzhen typical weather.(2) Secondly, we confirmed by experiments that we can analyze battery SEI film component by FTIR and some ingredients absorbance has correlation with the loss of capacity, and the absorbance can be used to characterize the battery calendar life.(3) Finally, we compare the predictive value and the true value about the calendar life of the two EV cars Yue B76Y**and Yue B G8X**. The annual average error of our prediction method for t the official vehicles Yue B76Y**is2.7%and the Yue B G8X**taxi’s half-life prediction error is8.7%, which in the current forecasting methods are better level.