The International Air Transport Association has forecast an annual growth rate of air traffic of over 4% in the next decades, which will translates into an increased generation of emissions. Therefore the European Commission has defined ambitious environmental goals for the aviation sector to drastically reduce greenhouse gas and noise emissions by the year 2050. This thesis shows one radical approach, which tries to reach these goals by a pure battery powered transport aircraft including the entire propulsion system. The first section describes the used and derived methodologies based on state-of-the-art technologies. In a second step these methodologies are implemented within an aircraft environment. The regional turboprop aircraft ATR 72-500 serves as baseline. For this reference a detailed mass breakdown of major systems and flight performance analysis are required first. The next step explains the electrification process showing possible solutions for the propulsion system and subsystems. Finally the results of the electrified aircraft are presented like a detailed mass breakdown of each main system as well as a flight performance analysis considering EU-OPS/FAA requirements.