The problem addressed was that of providing, through the use of novel materials and membranes, at minimum cost and inconvenience, an inexpensive and long-lived redox flow cell having redox-active compounds which, even in the possible event of cell failure, result in a low level of environmental pollution. The redox-active components envisaged in accordance with the invention are high molecular weight compounds such as redox-active polymers or oligomers, and the membrane envisaged is a size exclusion membrane (3) for separation of the high molecular weight redox-active components.
