A process for manufacturing a product comprising nanoelements, said process comprising the following steps: - forming a mixture comprising a plurality of electrically conductive grains, a catalyst separate from the grains of the plurality of electrically conductive grains, and a reactant that is liquid or in the form of a suspension of solid particles in a liquid solvent and comprises a precursor of the material intended to form the nanoelements, the grains being formed by a carbon-based material or an electrically conductive organic compound or an electrically conductive organometallic compound or an electrically conductive inorganic material such as a ceramic, and the material intended to form the nanoelements being chosen such that said material comprises silicon, germanium, or an alloy of silicon with one of the materials chosen from: germanium, tin, nickel, copper, or another transition metal, or an alloy of germanium with one of the materials chosen from: silicon, tin, nickel, copper, or another transition metal, - introducing the mixture into a chamber of a reactor and pressurizing the reactor to a pressure less than or equal to 1 bar, - sealing the reactor, - obtaining the product from the mixture comprising a step (E3-1) of growing said nanoelements from the catalyst, then combined with said grains of the plurality of electrically conductive grains, said growth step (E3-1) being carried out by a step of heat treatment applied to said mixture, the reactant containing a source of dopants for the material intended to form said nanoelements to modify its electrical characteristics, wherein the step of introducing the mixture into a reactor chamber and setting the reactor to a pressure below 1 bar is an intermediate step between the step of forming the mixture and the step of obtaining the product, and wherein, after the step of introducing the mixture into a reactor chamber and setting the reactor to a pressure below 1 bar, the reactor is then sealed. - forming a mixture comprising a plurality of electrically conductive grains, a catalyst separate from the grains of the plurality of electrically conductive grains, and a reactant that is liquid or in the form of a suspension of solid particles in a liquid solvent and comprises a precursor of the material intended to form the nanoelements, the grains being formed by a carbon-based material or an electrically conductive organic compound or an electrically conductive organometallic compound or an electrically conductive inorganic material such as a ceramic, and the material intended to form the nanoelements being chosen such that said material comprises silicon, germanium, or an alloy of silicon with one of the materials chosen from: germanium, tin, nickel, copper, or another transition metal, or an alloy of germanium with one of the materials chosen from: silicon, tin, nickel, copper, or another transition metal, - introducing the mixture into a chamber of a reactor and pressurizing the reactor to a pressure less than or equal to 1 bar, - sealing the reactor, - obtaining the product from the mixture comprising a step (E3-1) of growing said nanoelements from the catalyst, then combined with said grains of the plurality of electrically conductive grains, said growth step (E3-1) being carried out by a step of heat treatment applied to said mixture, the reactant containing a source of dopants for the material intended to form said nanoelements to modify its electrical characteristics,