An electrical energy storage device is provided which comprises at least one module with a negative electrode, a positive electrode made from an anion generating material or material combination and conducting anions, and an anion conducting solid electrolyte located between the negative electrode and the positive electrode. The negative electrode of each module comprises a porous structure that conducts anions and the pore space of which is at least partially filled by a first redox mass which comprises a metal/metal oxide pair. The positive electrode of each module comprises a porous structure that conducts anions and the pore space of which is at least partially filled by a second redox mass which comprises a metal/metal oxide pair with an increased oxidation potential compared to the first redox mass.