Study on direct parallel charging of lithium-ion battery and supercapacitor

Abstract

Abstract Currently, there are few studies on hybrid system charging, and the existing ones rely on many power electronic components to charge lithium-ion battery and supercapacitor, respectively. This paper mainly focuses on the direct parallel charging of lithium-ion battery and supercapacitor, which has simple structure and low cost. However, the capacity of the hybrid system can not be fully utilized due to the unreasonable current distribution during charging. This paper proposes a method that improves the charging effect: constant current charging under fine tuning the resistance distribution of battery branch and supercapacitor branch (CCFTR). The results show that although the charging time is increased slightly with the CCFTR, the charging capacity can increase significantly. Compared with the untreated constant current charging (CC), the charging time is only prolonged by 6.77 minutes with the CCFTR (50mΩ) at 22A (2.75C), but the charging capacity is increased by 48.4%, reaching 95.1% of the rated capacity. And the CCFTR can dramatically prolong the battery life. The effect is better under higher current. Compared to the CC with the same charging current, the CCFTR can extend the battery life by 11.37% at 2.75C and 26.02% at 3.75C.