composite materials made of a phase change material and carbon, phase change materials are selected from the group of water/ice, saline solutions, hydrates, paraffins, mixtures of these products and other products with high latent or melting heat at the solid/liquid phase transition point, the carbons are selected from the group of graphites, namely, electrographite, natural graphite, graphite salt, and expanded graphite, man-made carbons namely artificial carbon, amorphous carbon, carbon black, carbonized or graphitized carbon fibers, silicon carbide and titanium carbide; carbon pieces; carbon granules; carbon powders; foam structures made from carbon, namely, sheets, plates, hollow cylinders, and covers for use in manufacturing composite materials consisting of phase change materials and carbon materials; carbon laminates; graphite foils; carbon or graphite fibers; carbon or graphite textile products, namely, fabrics as plain weaves, twills, satin, tapes from unidirectional carbon or graphite fibers, felts, and fleeces for use in the manufacture of composite materials; carbon composites; components made from carbon, namely, plates with or without an embossed, pressed or machined flow field; and semi-finished products made from carbon or graphite, namely, foils, sheets, plates, rods and squared stones for use in the manufacture of composite materials

heat accumulators; and cold accumulators