This work aims to discuss the feasibility of including battery technologies to electrify aviation, highlighting their great potential, but also outlining some of the main technological challenges that will be faced in the coming years. The work is framed within the Environmentally Friendly Aviation for All Classes of Aircraft (EFACA) project, a project funded by the European Commission through the Horizon Europe Programme, which focuses on the analysis and development of new technologies to make aviation more sustainable. The first step in determining which applications of battery technology are most suitable for each type of aircraft is to have an overview of these technologies, understand the main challenges when including batteries in aviation (battery performance, safety issues, problems in battery manufacturing, and disposal), and study the performance metrics characteristic of each type and establish a battery classification. From batteries, based on such important characteristics as their specific energy requirements or operating profiles, it is possible to define aircraft types according to the different applications and extend the study to aircraft classes.