Accumulator

The accumulator (1) has a housing (2) and a housing cover (3) for closing the housing. Positive electrodes (4), negative electrodes (5) and an electrolyte (10) surrounding the electrodes are alternatingly arranged within the housing. A supplementary container (15) serves as a compensating reservoir for the electrolyte. A volume area (16) of the supplementary container and a volume area (17) of the housing stay in fluidic connection with each other. The supplementary container is arranged at the housing cover.