Research On Thermal Runaway Characteristic Of NCM Batteries Thorough Overcharge And Detecting Methods

Following by the people with so many cares about the environments very much,with the traditional oil provided cars,many people choose the electric car.Due to the high specific energy,high voltage platform,and low-temperature capability,NCM lithium batteries are increasingly selected as the power source for electric vehicles.However,in recent years,the heat caused by the irrational use of ternary lithium batteries Out-of-control accidents pose a great threat to people’s lives and property.Investigations have shown that overcharging is one of the typical causes of thermal runaway during the use of ternary lithium batteries.Therefore,it is of great research significance to analyze the overcharging characteristics of NCM lithium batteries,study the changes of characteristic parameters during overcharging of ternary lithium batteries,and construct ternary lithium battery overcharge detection methods.This article takes the 5Ah NCM lithium batteries as the research object,studies the mechanism of NCM lithium battery overcharge thermal runaway platform and designs an experimental program,carrying out a large number of ternary lithium Thermal runaway experiment of battery overcharge,to obtain voltage,temperature,gas and video data during the overcharge of ternary lithium battery.According to the characteristics of the overcharge temperature and voltage of the ternary lithium battery,the overcharge thermal runaway process of the ternary lithium battery is divided into three stages: the initial thermal runaway of the ternary lithium battery,the intermediate thermal runaway of the ternary lithium battery,and the overcharge of the ternary lithium battery is divided into three stages: the initial thermal runaway of the ternary lithium battery,the intermediate thermal runaway of the ternary lithium battery,and the overcharge of the ternary lithium battery End of thermal runaway.The appearance of the battery in the early stage did not change significantly.In the middle stage,the battery began to swell.At the end the battery caught fire or exploded or remained bulging.Before the explosion of the ternary lithium battery,the voltage and temperature of the ternary lithium battery showed an overall upward trend,and the voltage change rate and the temperature change rate were different at different stages.The ternary lithium battery gas is always generatedbefore the battery explodes.According to the changes of temperature,voltage and gas characteristic parameters in the entire process of ternary lithium battery overcharge thermal runaway,a ternary lithium battery overcharge early warning algorithm is constructed,which can determine whether the ternary lithium battery is overcharged and three overcharged stage.This paper developed a verification experiment to verify the ternary lithium battery overcharge warning algorithm.The verification test results show that the ternary lithium battery overcharge thermal runaway early warning algorithm is reliable,which can reliably warn the ternary lithium battery overcharge state and provide technical support for effectively preventing the ternary lithium battery overcharge fire accident.