基于直流阻抗谱的锂离子电池无损安全诊断OA

Li-ion batteries are widely used in electric vehicles and other fields,but the thermal runaway safety issue is of great concern.A method of battery safety diagnosis based on activation energy is proposed.The battery is first measured by direct current impedance spectroscopy(DCIS),then the activation energy of the electrode interface is analyzed by Arrhenius equation in combination with the temperature change characteristics of the impedance.The activation energy of lightly aged batteries is stable around 0.50 eV,while the activation energy of heavily aged batteries decays to around 0.35 eV.Transmission electron microscopy(TEM)analysis shows that the solid electrolyte interface(SEI)film of the heavily aged battery has obvious defects and cracks,while the SEI film of the lightly aged battery is relatively stable.Under high-current transport conditions,the damaged SEI film triggers a series of side reactions,leading to localized overheating,which becomes the main causative factor of thermal runaway in battery.Detecting the activation energy change by DCIS technology can realize the non-destructive detection of internal defects in batteries,which is a fast and low-cost method for battery safety diagnosis.