锂电池的电化学-热-力耦合建模与放电过程性能分析OA

To explore the role of multi-physics coupling mechanisms in the capacity attenuation of lithium-ion batteries,a multi-physics model of lithium-ion batteries with the coupling of electrochemical-thermal and mechanical fields is constructed.Taking cylindrical batteries as the research object,it reveals the coupling mechanisms among electrochemical reactions,thermal conduction and mechanical stress and their influence on battery performance.Then,the model is experimentally verified at discharge rates of 0.5C,1C and 1.5C,verifying that the simulation results are basically consistent with the measured data.The simulation analysis also reveals that the temperature variation of the battery is closely related to its degradation:in the early stage of discharge,ohmic heat is dominant,while in the later stage,reaction heat takes the lead.The temperature distribution shows a radial gradient,and the electrochemical heat generation causes the temperature to rise,which in turn accelerates ion diffusion and interface reactions,forming an electro-thermal feedback.Meanwhile,the deintercalation of lithium ions from the negative electrode and the intercalation of lithium ions into the positive electrode cause changes in the volume of electrode particles,thereby generating non-uniform stress concentration,inducing particle cracking and electrode structure loosening,and forming a thermo-mechanical feedback.The synergy of the three constitutes a coupled failure mechanism,significantly exacerbating the loss of active materials and capacity decline.