A storage module (1) comprises a storage zone (3) for storing flat articles (2) by accumulation in a stack and on edge, a main conveyor (9) that extends transversely to the storage zone, a stacking function for transferring an article from the main conveyor to the storage zone and for stacking it at the back of the stack of articles in the storage zone, and an unstacking function for extracting an article from the stack of articles and for transferring it to the main conveyor. The unstacking function comprises an unstacking plate (7) having a perforated belt and controlled suction and disposed between the main conveyor and the storage zone, said unstacking plate having a first segment parallel to the stack of articles and a second segment that is adjacent to the first segment and that extends slantwise relative to the first segment, said controlled suction being disposed in the slantwise second segment of the unstacking plate.