锂离子电池大电流快速充电成为近年来的发展趋势,但大电流充电很容易在电池内部引起严重极化,影响电池的性能与寿命.本文研究不同充电模式对锂离子电池极化特性的影响规律,首先,建立基于LiMn2O4/石墨电池的电化学-热耦合瞬态计算模型,充分考虑充电过程中电池内部的电化学过程和内热源实时变化,通过变电流充电时电池端电压变化和电解液浓度的空间分布规律,研究电池内三种极化的时变特性.然后,研究不同恒流充电倍率下电池端电压和极化电压随SOC的变化规律,提出表征电池极化程度和极化电压对电池充电过程影响的变量PA与SOCc,定量分析不同充电条件下极化电压对锂离子电池充电过程的影响.最后,研究Reflex快速充电条件下极化电压的变化规律,分析不同正向充电时间tch对电池极化及充电过程的影响,并给出了建议tch值.结果表明,极化电压受充电电流和SOC的直接影响,而其变化又直接影响电池端电压的变化,Reflex快充方法能有效抑制电池极化,减弱其对充电的影响.%High current fast charging of Lithium-ion battery has become a developing trend in recent years. However, high current charging will cause great polarization within the battery, which has great influence on its performance and cycle life. Lithium-ion battery polarization characteristics at different charging methods were investigated. Firstly, an electrochemical-thermal transient numerical model based on LiMn2O4/graphite was established. Herein, the electrochemical process and real-time heat source change were taken into full consideration. Secondly, variation current charging was utilized, and time-varying characteristics of three polarizations were analyzed based on cell voltage and spatial distributions of electrolyte salt concentration. Then cell voltage and polarization voltage along with SOC at different constant current charging rates were analyzed. Subsequently, two variablesPA and SOCc were defined to represent the degree of polarization and available capacity. Polarization voltage characteristics under different charging conditions were analyzed quantitatively. Finally, polarization of reflex fast charging influence of differenttch on charging was studied. The results show that polarization voltage is affected by charging current and SOC directly, while the polarization affects cell voltage on the other hand. Reflex fast charging can suppress the polarization voltage and weaken its influence on charging.
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