In this study, the duty-cycle of a commercial lithium-ion battery (LIB) for a typical passenger airplane (Bombardier CRJ200) is obtained and compared to the duty- cycle of the same LIB for electric vehicles. For this purpose, the velocity and altitude of the airplane is monitored during a typical flight and the instantaneous mechanical power of the airplane is obtained by modeling. Based on the airplane required power and the characteristics of the LIB, a battery pack is designed for the airplane. Then, the duty-cycle of a LIB cell in the battery pack is yielded. The duty-cycle of the same LIB for a typical electric vehicle is also obtained from modeling based on the Highway Fuel Economy Test (HWFET), New York City Cycle (NYCC) and United States 2006 (US06) drive-cycles. Finally, the duty-cycle of the LIB for two different applications of electric airplane and electric vehicle is compared. The duty-cycles obtained in this study can be employed to study the lifespan of LIBs.