Sorting Method Of Lithium-ion Battery Module Considering Secondary Utilization

The booming development of the new energy electric vehicle industry has brought a large number of retired power batteries.Secondary utilization of retried power batteries has high environmental and economic value.Based on the use of retired power battery modules,the paper studies the key issues in the process of the battery energy storage-the consistency of the modular component selection.The specific research content and conclusions are as follows:In this paper,Simulink was used as the simulation tool,and the four-cell series module was used as the simulation object.In view that the consistency of the battery module was influenced by multi-factor,on the basis of discussing the mechanism of battery capacity attenuation,the evolution law of modules and their series cells’capacity under seven kinds of consistency influencing factors are studied.The evolution of the module and its serial cells’ capacity was studied when the distribution of one single factor was inconsistent at the beginning of the simulation and the initial parameters of the other six factors are completely consistent.Subsequently,for the case that the conventional parameters of the individual cells in the module could not be accurately identified,the module’s discharge voltage curve was taken as the research object,and the curve shape similarity identification was carried out.The similarity transformation matrix including the tensile rotation amount,the x-axis translation amount and the y-axis translation amount was obtained,and the evolution law of the matrix parameters under different influencing factors was analyzed.On the basis of this,combined with the single factor influence simulation results,a module consistency re-sorting scheme based on the voltage curve similarity matrix parameters and considering the parameter weights was proposed and verified by experiments.The results showed that:1.Coulomb efficiency and temperature inconsistency contribute the most to the module’s capacity attenuation,followed by the capacity decay rate,initial internal resistance and growth rate are inconsistent.The initial SOC and initial capacity inconsistency would not aggravate the module attenuation.During the aging process of the module,the influence of factors on the module had weight and coupling characteristics.2.The sensitivity parameters of the similarity matrix corresponding to different influencing factors were varied.For the retired module,the identified matrix parameters could be used to replace the conventional electrical parameters to characterize the module consistency.3.On the basis of combining the influence weights,the battery module multi-parameter sorting scheme with the voltage curve similarity parameter as the new sorting parameter has better effect,and the subsequent decay rate of the sorted modules was more consistent.This rapid sorting method was beneficial to improve the safety and economy of the energy storage system.