Research On Key Technologies Of Screening And Recombination Of Retired Lithium-ion Batteries

Nowadays,the number of new energy vehicles is increasing year by year,and with the increase in the mileage and charging times of electric vehicles,the performance of electric vehicle power batteries is also gradually declining.When the performance of the electric vehicle power battery pack drops to 70%-80% of the performance of the factory battery pack,it will not be able to meet the needs of electric vehicles for cruising range and acceleration performance.At this time,the power battery of electric vehicles is facing the problem of retirement and scrapping.However,the performance of retired power batteries can still meet the needs of some low-speed electric vehicles and household energy storage.If the retired power batteries are directly scrapped,it will not only cause energy waste,but also bring great pollution to the global environment.Thesis takes the cascade utilization of retired lithium-ion batteries as the basic point,analyzes the working performance and aging mechanism of lithium-ion batteries,and builds a corresponding model according to the characteristics of retired batteries and method for evaluating the state of charge（SOC）and state of health（SOH）of lithium batteries is proposed.A scheme for the screening and recombination of decommissioned lithium-ion batteries based on cascade utilization is proposed.The details are as follows:Firstly,starting from the internal chemical reaction of lithium-ion battery,the reasons for the inconsistency of lithium-ion batteries in series-parallel battery packs are analyzed,which provides an important basis for the subsequent evaluation and screening of lithium batteries.Then,the current common lithium-ion battery models are listed.After comparison and analysis,and the MATLAB simulation platform is used to analyze and verify the reliability of the model.Finally,according to the performance requirements of decommissioned lithium-ion batteries in cascade utilization,various indicators for evaluating lithium-ion batteries are analyzed,and decommissioned lithium batteries in different states are screened through experiments,which provides a basis for the subsequent battery cascade utilization and reorganization scheme.