Optimization on charging of the direct hybrid lithium-ion battery and supercapacitor for high power application through resistance balancing

The purpose of this study is to fill the research gap of direct parallel charging for batteries and supercapacitors. However, a simple parallel connection between the two will create a disproportionate current distribution and limit the effective capacity utilization. Thus, two approaches have been evaluated in this study to maximize the capacity utilization under large current applications: pulse charging and constant current charging under fine-tuning the resistance distribution. The results show the fine-tuning resistance method is superior to pulse charging in terms of effective charging capacity and charging time. Compared with the pulse charging (50% duty cycle) at 2.75C, the fine-tuning resistance method (50 m omega) can shorten the charging time by 10.6 min and in-crease the charging capacity by 30.5%. Compared with the constant current charging (CC), the charging time is only prolonged by 6.8 min with this method, but the charging capacity is increased by 48.4%, reaching 95.1% of the rated capacity for the hybrid system. As for the battery life within the hybrid system, compared with the same capacity battery pack with the exact total charging current, the fine-tuning resistance method can extend the battery life by 8.2% at 2.75C and 14.2% at 3.75C.

Automated summary

The purpose of this study is to address the issue of direct parallel charging for batteries and supercapacitors. Two methods were evaluated to maximize capacity utilization under high current applications: pulse charging and constant current charging with fine-tuned resistance distribution. The results suggest that the fine-tuning resistance method outperforms pulse charging in terms of effective charging capacity and charging time. Compared to pulse charging at 2.75C, the fine-tuning resistance method reduces charging time by 10.6 minutes and increases charging capacity by 30.5%. Compared to constant current charging, the charging time only increases by 6.8 minutes while the charging capacity increases by 48.4%, reaching 95.1% of the rated capacity for the hybrid system. Furthermore, the fine-tuning resistance method can extend battery life by 8.2% at 2.75C and 14.2% at 3.75C compared to a battery pack with the same capacity and total charging current.