Cassio aircraft use electric motors for all-electric power during taxi, takeoff, primary flight, and landing. The hybrid feature with an internal combustion engine comes into play as a range extender, recharging the batteries while in flight, according to company officials. Additionally, this hybrid element serves as a backup in the event of a problem with the electric propulsion, they said.
Source: general aviationElectric-hybrid general aviation plane recharges batteries in flight