NOVELTY - Energy storage device comprises at least one flowable electrode comprising an electroactive zone between a current collector and an ion permeable membrane. The electroactive zone includes an ion-storing redox composition. The ion-storing redox composition is: a semi-solid ion-storing redox composition comprising a solid phase ion-storing redox material in an electrolyte; and/or a condensed liquid ion-storing redox composition comprising condensed liquid ion-storing redox material in an electrolyte.    USE - The energy storage device is useful in a vehicle including an all-electric vehicle or a hybrid electric vehicle, and in an electric car to provide a driving of at least 200 miles, as a stationary energy storage such as in grid services applications, or for storage of intermittent renewable energy sources such as wind or solar energy (all claimed).    ADVANTAGE - The device has high energy-density and high power-density.    DETAILED DESCRIPTION - Energy storage device comprises at least one flowable electrode comprising an electroactive zone between a current collector and an ion permeable membrane. The electroactive zone includes an ion-storing redox composition. The ion-storing redox composition is: a semi-solid ion-storing redox composition comprising a solid phase ion-storing redox material in an electrolyte, where the solid phase ion-storing redox material is capable of taking up releasing ions without dissolving in the electrolyte, and the solid phase ion-storing redox material is present at 5-70 vol.%; and/or a condensed liquid ion-storing redox composition comprising condensed liquid ion-storing redox material in an electrolyte, where the condensed liquid ion-storing redox material is capable of taking up or releasing ions, and the condensed liquid ion-storing redox material is present at at least 10 wt.%. An INDEPENDENT CLAIM is included for operating the energy storage device, comprising providing the energy storage device in an electrical circuit, and generating an electrical current through the electrical circuit.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of a redox flow battery.    Positive electrode current collector (110)    Negative electrode current collector (120)    Ion permeable separator (130)    Positive electrode flowable material (140)    Negative flowable electrode active material. (150)