Abstract: The invention relates to an electrolytic cell for obtaining aluminum, including a pot shell, at least one cathode block arranged at least partially in the pot shell, at least one anode suspended above the cell and dipping into the upper portion of the electrolytic cell, and an insulation at least partially covering the internal surface of the pot shell and located between the cathode block and the pot shell, the pot shell and the elements that it contains delimiting a crucible intended to receive an electrolytic bath in contact with the cathode block, characterized in that the insulation is at least partially made of carbon-based blocks having a heat conductivity lower than 1 W/m/K.

Abstract: This cathode (3) contains, within the pores in its structure, a carbon-containing product fired at a temperature of less than 1600° C., improving the erosion resistance by protecting the graphitized binder.

Abstract: In this cathode, which is a single block, the electrical resistivity is heterogeneous along its longitudinal axis, this resistivity being higher in the end regions of the cathode (3) than in the central region of the latter.

Abstract: Composition for a coating protecting the surfaces of carbon-containing products exposed to a hot, oxidizing environment such as the parts of anodes not immersed in the molten salt bath and the liners of the aluminum electrolysis cells and more generally the non-immersed parts of carbon-containing refractory elements used in electrolysis conducted below 950.degree. C. in a molten salt bath, comprising a geopolymer, preferably in the fluoropoly(sialate-disiloxo) family, the other components possibly being water as well as alumina and/or a refractory other than silica. Coating protecting the surfaces of carbon-containing products exposed to a hot, oxidizing environment such as the non-immersed parts of carbon-containing refractory elements used in electrolysis conducted below 950.degree. C. in a molten salt bath, including polysilicates and at least one inorganic polymer in the poly(sialate) family, preferably fluoropoly(sialate-disiloxo), also possibly with alumina or another refractory other than silica.