Bin Xu1,2, Lingxi Kong2, Guangrui Wen1 and Michael G. Pecht2
1 School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
2 Center for Advanced Life Cycle Engineering, University of Maryland, College Park, MD 20742, USA
18650 Lithium-ion batteries are wildly used as power sources for portable electronics because of the standardized format and economical manufacturing cost. However, commercial 18650 cells come in various designs due to the implementation of different protection devices. The current interrupt device and top vent are mandatory protection devices for all commercial 18650 Li-ion batteries. In contrast, the positive temperature coefficient thermistor, bottom vent, and protection circuit are optional protection devices that can be non-installed, installed separately, or combined in commercial 18650 batteries. Four representative commercial 18650 Li-ion batteries were disassembled and compared in terms of the similarities and differences of the protection devices. This paper overviews the working mechanism, advantages, and drawbacks of each protection device. Recommendations on battery selection and potential future trends are then provided.