ENERGY STORAGE SYSTEM

Disclosed is an energy storage system, in particular for use in a vehicle, preferably for use in a hybrid vehicle, wherein the energy storage system has the following: a multiplicity of lithium ion cells, a housing with an interior space for receiving the lithium-ion cells and having an opening and a cover device. A barrier layer is provided, at least in certain areas, between the interior of the housing and the inner faces of the housing which bound the interior. In this context, the cover device can be or is connected to the housing in such a way that the opening of the housing is or can be closed, specifically in such a way that the cover device forms, at least in certain areas, an outer face of the housing which is closed in this way. The cover device is preferably embodied as a cooling device for regulating the temperature of the energy storage system.