Energy storage device

The apparatus has a temperature-control system (2) arranged in a energy storage housing (3) and provided with a liquid temperature-control medium that flows for cooling and/or heating multiple battery cells (1) that are arranged in the housing. An absorbent element (4) is arranged between the cells and the housing such that any temperature-control medium flowing-out of the temperature-control system is absorbed by the absorbent element. An electrically insulating layer (5) is impermeable to the temperature-control medium and arranged spatially between the absorbent element and the cells. The absorbent element comprises a bulk material or a fluid-absorbing material such as non-woven fabric.