NOVELTY - The system has an electrolyte placed in a housing. A discharging assembly (300) is immersed in the electrolyte and comprises a space adjacent to discharging cathodes. A metallic material forms discharging anodes when positioned in the space. Another space is provided above the discharging assembly, and contains metallic material in excess of the metallic material in the former space. The discharging cathodes comprise an oxygen cathode for reducing oxygen. A pump circulates the electrolyte through the former space.    USE - Electrochemical system e.g. metal fuel cell such as regenerative metal fuel cell, for storing electricity in metal e.g. zinc, aluminum, iron, lead, magnesium and alloy (all claimed), for a mobile device i.e. vehicle. Can also be used as a metal-air battery system and a flow battery system.    ADVANTAGE - The oxygen cathode allows independent removal of individual oxygen cathode without affecting other cathodes in the discharging assembly for service and maintenance, thus allowing convenient changing of cathodes or cleaning of a cell container when needed. The system resolves challenging problems relating to feeding metallic materials into individual cells and removing discharged material out of cells without clogging or jamming, and allows the oxygen cathode to be constructed as a self contained component. The system allows the use the container made of single continuous piece of plastic material to contain elements that are in touch with an electrolyte inside the container, thus removing possibility of potential electrolyte leaking out the cell. The system can perform concurrent charging and discharging functions, allows large capacities and flexible and low cost capacity scaling, allows charging and discharging to be operated at different locations, and allows energy storage for long times at low cost as active materials can be stored in simple plastic containers.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for generating and storing electricity.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of cells in a container with a chamber beneath each cell.    Cell container (110)    Wall (112)    Charging assembly (200)    Discharging assembly (300)    Surface (401)    Filter material (1101)