Light atoms such as lithium also play an important role in battery research, which means that ED, with its high sensitivity to these atoms, offers special possibilities. However, investigating battery models under working conditions during charging and discharging processes with conventional ED devices in the 100–300 keV range is extremely difficult or even impractical. On the one hand, it is experimentally very difficult to seal the battery cells against the surrounding ultra-high vacuum when using liquid electrolytes. On the other hand, due to the very low penetration power, only extremely thin battery models can be investigated, which are very fragile and break very easily. The higher penetration power of the electrons at REGAE should make it possible to investigate significantly thicker and therefore more stable battery models (Figure 4). In addition, it should be possible to investigate battery models with liquid electrolytes under stable environmental conditions using the same experimental chamber that is to be used for the investigation of hydrated biological samples. Furthermore, the relativistic electrons used here are significantly less susceptible to interference from the electric fields used to charge and discharge the batteries. Overall, REGAE therefore offers excellent and unique opportunities for operando experiments on batteries.