Electrochemical device, electrolytic cells and methods of operating them, and apparatuses comprising such cells

Abstract

The present invention provides an electrochemical device (1b) for use in an electrochemical apparatus, such as in an electrolytic cell. The device (1b) comprises an electrode (10), a conduit (20) and an interface layer (90). The electrode (10) has a first part (12) for immersion in an electrolyte (40), a second part (14) for making electrical contact with a current-carrying conductor (30c), and a third part (16) between the first and second parts (12, 14) for making thermal contact with a heat transfer fluid (HTF). The conduit (20) is arranged to bring the heat transfer fluid (HTF) into thermal contact with the third part (16) of the electrode (10) via the interface layer (90), which is between and in thermal contact with both the third part (16) of the electrode (10) and an interior (22) of the conduit (20). The interface layer (90), which is made of a thermally conducting and electrically insulating material, electrically isolates the electrode (10) from the HTF in case the HTF is electrically conducting, and also protects the electrode (10) against chemical attack by the HTF. The electrode (10) is made of carbon, which has reduced electrical resistivity and thermal conductivity at temperatures above ambient. Therefore, if the third part (16) of the electrode (10) is heated by means of the HTF, its electrical resistivity and thermal conductivity are reduced. The former enables more efficient flow of electrical current between the first and second parts (14, 16) of the electrode and therefore reduces the total internal resistance of any electrochemical apparatus in which the electrochemical device (1a) is used. The latter reduces the flow of heat between the first and second parts (14, 16) of the electrode (10) and therefore helps to prevent heat loss from such an electrochemical apparatus via the electrode (10) to the current-carrying conductor (30c). Both effects make the electrochemical apparatus more energy efficient. The device may also be used to inject waste heat from another process, such as from an exothermic chemical reaction, into the electrochemical apparatus. This reduces the electrical power consumption of the electrochemical apparatus and also makes the combination of the electrochemical apparatus with the other process supplying the heat more energy efficient overall. The invention also provides electrolytic cells comprising such an electrochemical device, methods of operating such electrolytic cells, and apparatuses comprising such cells. The invention is particularly suited to producing Group 1 and Group 2 metals by electrolysis with increased energy efficiency.

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