The flywheel has high energy storage density and high instantaneous power. It can output more energy in a short time, which is conducive to the launch of the electromagnetic gun and the rapid start of the vehicle. When energy is extracted from the system, the flywheel's rotational speed is reduced as a consequence of the principle of conservation of energy; adding energy to the. The lithium-ion battery has a high energy density, lower cost per energy capacity but much less power density, and high cost per power capacity. It is characterized by full magnetic levitation, low energy consumption, fast response, long life, high number of charge and discharge cycles. For discharging, the motor acts as a generator, braking the rotor to.