ELECTROCHEMICAL CELLS

Novel electrochemical cells are provided herein. In such cells, one electrode is an expanded mass of particulate material, means for passing an electrolyte through the expanded electrode and a counterelectrode in direct electrical contact with at least some particles of the expanded electrode, the counterelectrode being electrically conducting but having a contact resistance in air between itself and copper test surface of at least 10 times the contact resistance under the same conditions of measurement between the copper test surface and another surface of copper. An electrolyte is passed through the particulate electrode, possibly for fluidising and/or circulating the particles of the electrode. Suitable particulate materials include ruthenium oxide, lead oxide nad iron oxide. Whereas in previous cells of this kind, a diaphragm has been arranged between the particulate electrode and the counterelectrode of the cell, it has been discovered that such a cell can be operated with the counterelectrode actually in contact with particles of the particulate electrode provided the material of the surface of the counterelectrode is suitably chosen.