The aviation industry faces significant challenges in achieving climate neutrality by 2050, requiring a transition to advanced propulsion technologies and energy storage systems. This chapter examines the role of battery technologies in enabling electrified aircraft, assessing the current state-of-the-art battery systems, certification standards, and key performance indicators. It explores full-electric, hybrid-electric, and more-electric aircraft architectures, evaluating their feasibility across market segments and projecting battery performance requirements, the airborne battery market, and emission reductions through electrification by 2050. Case studies from ongoing European projects, such as HERA and HECATE, alongside industrial programs like Heart Aerospace’s ES-30 and ATR-EVO, are also discussed. Additionally, a structural battery concept is presented as a disruptive innovation for multifunctional energy storage, highlighting its potential to achieve higher energy densities compared to conventional integration concepts. The findings indicate that while battery technology advancements are critical for decarbonizing aviation, hybrid-electric and more-electric architectures will contribute approximately 3.5% to total emissions reductions. Though modest, this impact represents about 10% of the emissions reductions expected from technological developments by 2050. Future progress in safe, high-energy–density batteries and certification frameworks will determine the pace of electrification in commercial aviation, shaping the industry’s long-term sustainability.