The Study Of Lithium-ion Battery Life Based On Multiple-factor Analysis

Energy and environmental problems become increasingly serious,making people attach importance to the application of electric vehicles.Compared with the traditional car,because lithium battery life is too short,has become one of the key issues restricting the promotion of electric vehicles.Based on the mechanism of single cell decay and battery inconsistency,the paper focuses on the research of battery life and the inconsistency of battery life.The specific contents and conclusions are as follows:(1)On the basis of studying the working principle of lithium battery,the internal factors of lithium battery life decline are analyzed,and the reduction of the number of activated lithium ions is the dominant factor.The main factors of external influence battery life from the battery to find the actual operating conditions is the temperature,depth of discharge and discharge rate,and external factors deduced contact with declining battery life from the viewpoint of the reaction rate and mechanism of polarization mechanism.(2)Aiming at the difficult problem of battery capacity data in real vehicle condition,this paper proposes a capacity estimation method based on multi-factor correction: the discharge depth is corrected by using the discharge DV curve;Considering the actual temperature rise of the battery to solve the equivalent temperature,the use of the battery at different temperatures and current discharge power difference between the completion of the temperature and current correction,and the use of NASA battery experimental data validation,the results show a very high accuracy.Based on the revised capacity data,the battery decay situation under different factors is compared and analyzed.And taking into account the impact of the EIS test on the battery decline,the final analysis concluded that: if the normal charge and discharge cycle,insert the shallow shallow release conditions can extend battery life.(3)Based on the analysis of the cause and manifestation of battery pack inconsistency,it is concluded that battery inconsistency has statistical and coupling characteristics.Based on the NASA battery data,the battery model was established.Based on the numerical simulation method,the effect of the inconsistency of the parameters on the inconsistency was analyzed.The results showed that the inconsistency of the parameters was more and more inconsistent.Based on the battery pack iteration process to deduce the battery capacity decline,and finally concluded: the greater the degree of initial inconsistencies,the shorter the battery life.