Method for manufacturing a thermoelectric structure by deposition under concentrated energy

Abstract

Method for manufacturing a thermoelectric structure by concentrated energy deposition. The invention relates to a method for manufacturing a thermoelectric module (10) for generating a thermoelectric effect, comprising at least the steps of: Providing a substrate (20), Forming on the substrate (20) a plurality of thermoelectric units (15), each comprising two thermoelectric elements (11, 12) doped with different types of doping, the two thermoelectric elements (11, 12) being electrically connected to each other on the side of the substrate (20) and / or on the side opposite the substrate (20), the two thermoelectric elements (11, 12) being at least partially formed by a concentrated energy deposition method. Figure for the abstract: Fig. 1

Description

Title of the invention: Method for manufacturing a thermoelectric structure by deposition under concentrated energy technical field

[0001] The present invention relates to a method for manufacturing a thermoelectric structure by a concentrated energy deposition method. Previous technique

[0002] Thermoelectric modules are generally made of p-type and n-type doped materials and comprise pads arranged on a substrate. The pads are electrically connected in series by metallic junctions and thermally connected in parallel.

[0003] The electrical performance of a thermoelectric device in generator mode is given by: a. An internal electrical resistance Rint at the junction between p-type and n-type doped materials determined as follows:

[0004] Rint = N x pnp x H / A + Rc + Rmet

[0005] With N the number of junctions between the p-type and n-type doped materials of the structure, pnp is the charge density at the pn junctions, H the length of a line or a pad, A the cross-section of a line or a pad, Rc the total resistance of the contacts and Rmet the total resistance of the metallic junctions, a. A useful electrical power Pu = V2 / 4Rint.

[0006] To have a high useful electrical power, it is therefore necessary to have in particular a low electrical resistance Rint and therefore limit the contribution to the resistance of the total resistances of the contacts Rc and the total resistance of the metallic junctions.

[0007] The manufacture of thermoelectric modules is generally carried out from several stages: the manufacture of thermoelectric materials in particular by sintering, the shaping of the pads, their metallization and the assembly with the substrate.

[0008] EP3985745 is known for a method of manufacturing a thermoelectric device. The method includes several steps, among which are the fabrication of comb-shaped parts, their mechanical and electrical assembly, followed by cutting to form the thermoelectric junctions.

[0009] FR3140994 relates to a method for manufacturing thermoelectric structures using additive manufacturing techniques such as laser powder bed fusion or selective laser sintering and may include a substrate removal step to obtain the final structure.

[0010] FR3140993 also describes a method for manufacturing thermoelectric structures using additive manufacturing techniques, preferably laser powder bed fusion or selective laser sintering. These manufacturing processes require assembly steps and do not allow for the fabrication of thermoelectric devices on complex-shaped surfaces.

[0011] The article J. Lee, S. Choo, H. Ju, J. Hong, SE Yang, F. Kim, DH Gu, J. Jang, G. Kim, S. Ahn, JE Lee, SY Kim, HG Chae, JS Son, Doping-Induced Viscoelasticity in PbTe Thermoelectric Inks for 3D Printing of Power-Generating Tubes. Adv. Energy Mater. 2021, 11, 2100190. describes thermoelectric modules manufactured by an additive manufacturing method, specifically solution printing, a 3D printing method. PbTe particles are synthesized, and colloidal inks are then produced from these particles. The inks are then extruded using a 3D printer, dried, and heat-treated. The resulting objects are then assembled to form thermoelectric modules.

[0012] The article Hue et al. ACS Applied Materials and Interfaces 2023, Vol 15 / Issue 32, 3D Printing of Bi2Te3-Based Thermoelectric Materials with High Performance and Shape Controllability also describes thermoelectric modules manufactured by an additive manufacturing method, in particular by selective laser melting, to obtain thermoelectric modules in the shape of half-rings.

[0013] There is therefore a need to develop a manufacturing process for thermoelectric modules that allows for the production of thermoelectric modules without assembly steps, with complex shapes to adapt to different support shapes, while improving the thermoelectric properties of the thermoelectric modules. Description of the invention

[0014] The present invention addresses this need by means of a method for manufacturing a thermoelectric module capable of generating a thermoelectric effect, comprising at least the steps of: a. Provision of a substrate, b. Formation on the substrate of a plurality of thermoelectric units each comprising two thermoelectric elements doped according to different types of doping, the two thermoelectric elements being electrically connected to each other on the side of the substrate and / or on the side opposite the substrate, the two thermoelectric elements being at least partially formed by a concentrated energy deposition method.

[0015] The invention also relates to a thermoelectric module manufactured according to the process as mentioned above.

[0016] The use of a concentrated energy deposition method makes it possible to deposit materials onto a wide variety of substrate shapes, including cylindrical substrates, which is not possible or is complex with other additive manufacturing processes such as laser powder bed fusion. This allows modules to be built directly onto substrates adapted to the shape of the thermal source, particularly heat or cold, facilitating the manufacture of such modules and thus improving yields.

[0017] Thus, deposition under concentrated energy allows the manufacture of modules of complex shapes, such as cylindrical modules, which may be more suitable for certain heat sources to be dissipated.

[0018] Furthermore, the concentrated energy deposition technique can be performed with a plurality of nozzles emitting powder of the materials to be deposited towards the melting zone, as we will see later. The presence of multiple nozzles allows for the deposition of different materials using different nozzles. In particular, this makes it possible to form p-doped and n-doped thermoelectric elements without having to change the powder in the device, using different nozzles. This simplifies manufacturing and improves the accuracy of the fabrication and the junction between the two materials. This can improve the energy performance of the thermoelectric module, notably by reducing electrical resistance at the junctions.

[0019] Concentrated energy deposition also allows for a wide variety of thermoelectric unit shapes. This enables greater versatility in the configuration of thermoelectric modules and their performance, making it possible to manufacture a custom thermoelectric module based on the desired performance, shape, and available space. Certain thermoelectric element shapes, in particular, can improve the size of the thermoelectric units within a module, allowing for better optimization of space within the thermoelectric module and thus improving module performance for the same footprint.

[0020] It is therefore possible, depending on the situation, in particular the specifications and the environment, to have modules whose shape and dimensions are adapted to each situation.

[0021] Concentrated energy deposition also allows for great versatility in the electrical configuration between the thermoelectric elements, in particular connecting the thermoelectric elements in series or in parallel to adapt the performance. Electrical junction

[0022] The two thermoelectric elements of the same thermoelectric unit can be electrically connected to each other by direct contact between them or by an internal electrical junction.

[0023] Thermoelectric elements may consist of one or more pads of the same doping. Preferably, the thermoelectric elements consist of a single pad. Alternatively, the thermoelectric elements consist of several pads, these being of the same doping and electrically connected both on the substrate side and on the side opposite the substrate, the pads then being connected in parallel with each other.

[0024] Each thermoelectric element of each thermoelectric unit can further be electrically connected to an adjacent thermoelectric element of different doping of another different thermoelectric unit or to an electrical connector by direct contact or by an external electrical junction.

[0025] Preferably, each of the two longitudinal ends of the thermoelectric elements is connected to another thermoelectric element of different doping or to an electrical connector.

[0026] Internal and / or external electrical junctions can be formed by the local deposition, between the two thermoelectric elements, of a layer of a mixture of the two materials composing the two thermoelectric elements, or by the deposition of a metallic track in contact with the two thermoelectric elements. In the case of a layer of a mixture of the two materials composing the two thermoelectric elements between the two thermoelectric elements, this layer can extend between two opposing lateral surfaces of the thermoelectric elements. The deposition of the mixture can be carried out by deposition under concentrated energy, in particular as described below.

[0027] In the case of direct contact or electrical mixing junction between thermoelectric elements of different dopings, the median surface of the thermoelectric unit forming the separation between the two thermoelectric elements may be greater than or equal to 50%, preferably greater than or equal to 70%, of the surface of a cross-section of a thermoelectric element.

[0028] Where the internal electrical junctions and / or external electrical junctions are metallic tracks in contact with the two thermoelectric elements. The metallic track can be deposited in the form of one or more discontinuous layers by any deposition method on the substrate when it is on the substrate side, and / or on the thermoelectric elements when it is on the side opposite the substrate. Thermoelectric units

[0029] Preferably, the two thermoelectric elements of each thermoelectric unit have substantially identical structures except for the doping. Preferably, the two thermoelectric elements are made of identical materials doped differently.

[0030] Alternatively, the two thermoelectric elements of each thermoelectric unit are made of different thermoelectric materials doped differently.

[0031] Preferably, the two thermoelectric elements of each thermoelectric unit are connected to each other at one of their ends.

[0032] The thermoelectric elements can each be made of a single material.

[0033] Alternatively, the thermoelectric elements are multilayered. They can comprise several layers of different materials doped with the same type of doping. This can allow for broader mechanical properties, particularly thermal compatibility, by having a combination of thermoelectric materials adapted to different temperature ranges.

[0034] Preferably, the layers of different doped materials can be separated from each other by one or more interface structures.

[0035] The interface structure(s) may include at least one layer of a diffusion barrier material, in particular copper or nickel. Such interface materials limit diffusion between the two thermoelectric elements, ensure good electrical contact, particularly low resistance, and limit thermal expansion problems between the two thermoelectric elements.

[0036] The interface structure may be multilayered and comprise a layer of a material forming a diffusion barrier sandwiched between two layers of a thermoelectric material different from the thermoelectric materials it separates. Material

[0037] The thermoelectric elements may be made of silicon (Si), a silicon and germanium alloy (SiGe), bismuth telluride (Bi2Te3), skutterudites, a Half Heusler alloy or lead telluride.

[0038] Arrangement of the thermoelectric elements in relation to each other

[0039] The thermoelectric elements can be inclined on the substrate with respect to the axis perpendicular to the substrate at their base.

[0040] Preferably, in the case of direct contact of the thermoelectric elements, the two thermoelectric elements of each thermoelectric unit are inclined on the substrate with respect to the axis perpendicular to the substrate at their base in opposite directions. They may be inclined at an angle α between 5° and 70°. The angle may depend, in particular, on the expected thermoelectric performance, the required mechanical strength, the materials, and / or the height of the elements. In the case of a cylindrical substrate with a circular cross-section, the angle α may be substantially equal to 360 / n, where n is the number of thermoelectric units arranged around a cross-section of the substrate.

[0041] The electrically connected thermoelectric elements may be spaced a non-zero distance apart along their entire height. The distance may be constant along the entire height. The opposing lateral surfaces of the thermoelectric elements may be parallel to each other.

[0042] Alternatively, the distance between the two thermoelectric elements of the thermoelectric units is variable.

[0043] Adjacent thermoelectric elements may have identical spacing between them. Alternatively, at least one thermoelectric element has different spacings with the two thermoelectric elements to which it is electrically connected. Shape of thermoelectric elements

[0044] The thermoelectric elements are each preferably elongated along a longitudinal axis.

[0045] Preferably, the thermoelectric elements are each symmetrical with respect to their longitudinal axis.

[0046] The thermoelectric elements may each be symmetrical with respect to their median axis perpendicular to the longitudinal axis. Alternatively, the thermoelectric elements may each be asymmetrical with respect to said median axis.

[0047] Thermoelectric elements can all be substantially the same shape.

[0048] In the case of thermoelectric elements that are asymmetrical with respect to their median axis, the two thermoelectric elements of the thermoelectric units may have complementary shapes, in particular being substantially interlocking. This allows the thermoelectric elements to be brought closer together, which reduces the size of the thermoelectric units and allows for a greater number of thermoelectric units per unit area. Alternatively, the two thermoelectric elements of the thermoelectric units may be arranged in the same direction.

[0049] Alternatively, at least two thermoelectric elements are of different shapes, in particular the two thermoelectric elements of all the thermoelectric units are of different shapes, in particular complementary.

[0050] Thermoelectric elements may be cylindrical in shape with any base and a lateral surface extending onto the substrate. The base of the cylinder may be in the shape of a quadrilateral, in particular a rectangle or an isosceles trapezoid, an hourglass symmetrical or asymmetrical with respect to the median plane, a circular sector in the form of blocks of substantially parallelepiped shape, or have a surface at their base that is less than or equal to

[0051] Thermoelectric elements may have, between the base and the apex, a localized narrowing having a lateral width less than the width of the apex and / or the base.

[0052] Thermoelectric elements may have a surface at their base that is different from the surface at their top, in particular one of the two surfaces may be larger than the other for a substantially identical contour or vice versa.

[0053] Thermoelectric elements may have branches extending towards the base and / or the apex. The branches may be inclined relative to each other. The branches may join at their base. Thermoelectric elements may be Y-shaped or X-shaped. Alternatively, the branches may be spaced apart along their entire height.

[0054] Thermoelectric elements can be hollow or solid.

[0055] Thermoelectric elements may have recesses, in particular lateral notches along their height or a recess at their base or top. This makes it possible, in particular, to lighten the thermoelectric module, reduce the amount of material used, and increase the temperature difference between the top and the base of the thermoelectric elements under operating conditions.

[0056] The base of the thermoelectric elements may be of complementary shape to the substrate, in particular be a curved surface in the case of a cylindrical substrate with a circular base having the same radius of curvature as the substrate.

[0057] The apex of the thermoelectric elements can be a flat or curved surface. The curved surface of the apex can have the same radius of curvature as the substrate. Concentrated energy deposition method

[0058] Concentrated energy deposition can be performed using a device comprising a single nozzle for projecting the material to be deposited or a plurality of nozzles for projecting the material to be deposited. As mentioned previously, the presence of multiple nozzles allows for the deposition of different materials by different nozzles. In particular, this makes it possible to form p-doped and n-doped thermoelectric elements without having to change the powder in the device, using different nozzles. This simplifies manufacturing and improves manufacturing and junction accuracy. This can improve the energy performance of the thermoelectric module, notably by reducing electrical resistance at internal and / or external electrical junctions. Simultaneous filing

[0059] In the case of a plurality of projection nozzles, at least two nozzles may be connected to separate reservoirs, in particular each nozzle being connected to its own reservoir. In this case, the nozzles connected to separate reservoirs may be supplied with material from the reservoir independently.

[0060] Preferably, in this case, at least one or more first nozzles are connected to one or more reservoirs containing an n-type doped material to form one of the thermoelectric elements of each thermoelectric unit at least in part and at least one or more other second nozzles are connected to one or more reservoirs containing a p-type doped material to form the other of the thermoelectric elements of each thermoelectric unit at least in part.

[0061] The first and second nozzles can be controlled independently or synchronously to deposit only one of the two materials or a mixture of the two materials. This limits the handling of the deposition device for the formation of the thermoelectric module, as the differently doped materials for the thermoelectric elements can be introduced upstream into the deposition device, and the deposition can be performed programmatically without external intervention. This also improves the positioning accuracy of the thermoelectric elements and, in particular, enables the creation of internal electrical junctions by direct contact with greater precision and therefore a better quality of connection.

[0062] It is thus possible to deposit only the p-type material, in particular to form at least one thermoelectric element, or only the n-type material, in particular to form at least the other thermoelectric element, or to deposit a mixture of the n- and p-type materials, in particular to form the internal and / or external electrical junction between the thermoelectric elements. Thus, the deposition of the two thermoelectric elements of a thermoelectric unit, at least in part, can be carried out by projecting two materials doped with different types of doping through different nozzles of the concentrated energy deposition device.

[0063] The thermoelectric units can be formed, at least in part, by the alternating deposition of a p-type doped material and an n-type doped material for each thermoelectric unit, alternating the material projection through the first nozzle(s) and the second nozzle(s). This makes it possible, in particular, to manufacture the module, at least partially, without having to manipulate the deposition device, and it allows for better identification of the thermoelectric elements relative to each other.

[0064] The internal electrical junction(s) and / or the external electrical junction(s) electrically linking the two parts of thermoelectric elements can be formed between two thermoelectric elements by the simultaneous deposition of the two different doping materials by the first and second nozzle(s).

[0065] The alternating projections by the first nozzle(s) and by the second nozzle(s) as described above may include overlapping areas of material projection by the first and second nozzle(s) to form the internal electrical junctions as described above. This allows in particular to have electrical connections formed during the deposition process of thermoelectric elements at least partly by continuity of material and in particular to eliminate the need for connections by additional metallic tracks.

[0066] In the case of multilayer thermoelectric elements, the process may comprise a. the deposition under concentrated energy of the base of the thermoelectric elements in a first material with optionally the internal or external junctions to the base on the support or on conductive tracks as described above, b. the deposition, by any suitable method, of the interface structure onto the parts of the thermoelectric elements formed and then c. deposition by concentrated energy deposition of the top of the thermoelectric elements in a second material different from the first with optionally the internal or external junctions at the top of the thermoelectric elements as described previously.

[0067] In the case of additional intermediate layers in a thermoelectric material, the process may additionally include, between steps b) and c), as many times as there are intermediate layers, the deposition under concentrated energy of the layer of thermoelectric elements in an additional material on the interface structure deposited previously as described above, and then the deposition by any suitable method of an interface structure on the parts of the thermoelectric elements formed previously.

[0068] The process may include changing the material in the reservoirs of the concentrated energy deposition device for each deposition step. Alternatively, the device may include at least as many reservoirs as there are materials required for concentrated energy deposition, and the various deposition steps described above are carried out using different nozzles. Successive deposit

[0069] Alternatively, all the nozzles can be connected to the same reservoir of material to be deposited. It is then necessary to change the material for each new material and each type of doping. The process may include at least one step of changing the material to be deposited in the concentrated energy deposition device.

[0070] Alternatively, the thermoelectric units can be formed by depositing different materials and different dopings one after the other, depending on the structure of the thermoelectric elements. In the case of thermoelectric elements made of a single material, the process can involve, in a first step, the deposition of all the p-type doped thermoelectric elements and then, in a second step, the deposition of all the n-type doped thermoelectric elements. This can be done by changing the material to be deposited in the deposition device under energy concentrated, particularly in the case of a single reservoir for all nozzles, and / or by controlling the deposition via different nozzles. The process may optionally include a third step of forming an internal and / or external electrical junction by deposition of a mixture of p-type doped material and n-type doped material and / or the deposition of metallic tracks to form the internal and / or external electrical junctions. Formation of electrical tracks

[0071] The process may include a step of depositing metallic tracks on the substrate and / or on the thermoelectric elements to form the internal and / or external electrical junctions.

[0072] The process may include the deposition on the substrate, prior to the deposition of the thermoelectric elements, of a discontinuous metallic layer to form at least part of the internal or external electrical junctions in the form of conductive tracks.

[0073] The process may include depositing on the thermoelectric elements, after the deposition of the thermoelectric elements, a discontinuous metallic layer to form at least part of the internal or external electrical junctions in the form of conductive tracks. Substrate

[0074] The substrate is preferably made of an insulating material. It can be made of ceramic, in particular AIN, mullite, CN.

[0075] The substrate may be cylindrical with a polygonal base, in particular rectangular, square, pentagonal or hexagonal, circular or elliptical.

[0076] Alternatively, the substrate may be of another shape, in particular forming a flat or convex surface or a more complex surface. Series / parallel

[0077] Preferably, the module forms a thermoelectric circuit between a first thermoelectric element and a last thermoelectric element, the first and last thermoelectric elements being electrically connected by one of their ends to an electrical connector and the thermoelectric elements between the first and last thermoelectric element being all electrically connected to at least two adjacent thermoelectric elements to form the thermoelectric circuit between them.

[0078] In the case of a cylindrical substrate, the thermoelectric elements can be arranged in circumferential rows in which the thermoelectric elements are electrically connected to each other, with two thermoelectric elements in each circumferential row being electrically connected to the nearest thermoelectric element in a previous row and a row posterior along the longitudinal axis of the substrate respectively with the exception of the first and last circumferential row which are each connected to an electrical connector.

[0079] Alternatively, the thermoelectric elements can be arranged in longitudinal rows in which the thermoelectric elements are electrically connected to each other, the first and last thermoelectric element of each longitudinal row being electrically connected to the nearest thermoelectric elements of the adjacent longitudinal rows except for two adjacent longitudinal rows each connected to an electrical connector. Thermoelectric elements connected in series

[0080] In each thermoelectric unit, the first and second elements can be electrically connected to each other only on one side of the substrate and on the opposite side. In this case, the thermoelectric elements are connected in series. Thermoelectric elements connected in parallel

[0081] Alternatively, in at least one thermoelectric unit, the first element and the second element are electrically connected to each other on the substrate side and the opposite side of the substrate. In this case, at least the circuit comprises elements electrically connected to each other in parallel. Support structure

[0082] The process may include depositing a support structure onto the substrate, the support structure comprising support elements configured to extend between the thermoelectric elements and to serve as a support for the deposition of the thermoelectric elements during their deposition under concentrated energy. This deposition is preferably carried out prior to the deposition of the thermoelectric elements under concentrated energy.

[0083] The support elements may include an electrically insulating material and / or a sacrificial material.

[0084] In the case of thermoelectric elements inclined with respect to the axis perpendicular to the substrate at their base, the support elements can extend beneath the thermoelectric elements. This facilitates the deposition of the thermoelectric elements by deposition under concentrated energy.

[0085] In the case of thermoelectric elements in contact with each other, the support elements can extend between the TE elements in contact with each other at their apex.

[0086] Preferably, the support elements are all identical and made of the same material.

[0087] They can be deposited on the substrate by any suitable method, in particular by 3D printing, particularly using the concentrated energy deposition method. At least One of the nozzles of the concentrated energy deposition device can be connected to a reservoir containing the material constituting the support elements.

[0088] The support elements may have a thermal conductivity less than or equal to that of the thermoelectric elements.

[0089] The support elements may be made of an electrically insulating material. The electrically insulating material may be a ceramic, in particular silica, mica or Macor®. The ceramic may be solid or porous.

[0090] Alternatively, the support elements are made of a sacrificial material, the process further comprising a step of removing the sacrificial material by a suitable method, in particular by chemical means or by heating. The sacrificial material may be ceramic or metal, in particular silica or aluminum nitride. It is possible to have support elements that are only visible during the manufacturing process but are no longer visible on the thermoelectric module and form hollow areas.

[0091] Alternatively, the support elements may have a more complex structure, in particular comprising a skin layer and a core layer. The skin layer may be made of an electrically insulating material and the core layer of a sacrificial material. Additional steps

[0092] The process may include, after the formation of the thermoelectric units, an annealing step. The annealing step may involve heating the formed module to a temperature greater than or equal to 100°C in a furnace under an inert atmosphere, in particular an argon atmosphere. Such annealing makes it possible, in particular, to modify the microstructure of the thermoelectric elements to improve the microstructure of the formed module. This can also make it possible to reduce the mechanical stresses accumulated in the module during manufacturing and thus improve the mechanical and thermoelectric properties of the thermoelectric module. Brief description of the drawings

[0093] [Fig. 1] schematically represents in cross-section an example of a cylindrical thermoelectric module,

[0094] [Fig.2] schematically represents an example of a process,

[0095] [Fig.3] schematically represents a variant of a thermoelectric module,

[0096] [Fig.4] schematically represents different variants of plot shapes thermoelectric s,

[0097] [Fig.5] schematically represents in cross-section a variant of the module thermoelectric

[0098] [Fig.6] schematically represents in cross-section a variant of a thermoelectric module,

[0099] [Fig.7] schematically represents in cross-section a variant of a thermoelectric unit,

[0100] [Fig.8] schematically represents a variant of the process,

[0101] [Fig.9] schematically represents a variant of the process,

[0102] [Fig. 10] schematically represents a variant of the support structure, and

[0103] [Fig. 11] schematically represents a variant of the process.

[0104] [Fig. 12] schematically represents in cross-section a variant of a thermoelectric module. Detailed description

[0105] In the following description, identical elements or elements with identical functions 10 bear the same reference numeral. For the sake of brevity in this description, they are not described opposite each of the figures; only the differences between the embodiments are described.

[0106] Figure 1 illustrates a thermoelectric module (10) comprising a cylindrical substrate (20) with a circular base, carrying thermoelectric units (15) electrically connected to each other by external electrical junctions (32). The substrate is preferably made of an insulating material. It may be ceramic, in particular AIN, mullite, or CN.

[0107] The thermoelectric units each comprise two differently doped thermoelectric elements (11, 12) connected to each other by internal electrical junctions (31). The thermoelectric units (15) are arranged on the substrate (20) so that the thermoelectric elements (11, 12) have alternating doping levels around the substrate (20).

[0108] In the embodiment of [Fig. 1], the thermoelectric units (15) are all identical. However, the invention is not limited to identical thermoelectric units (15). At least two thermoelectric units (15) could be of different shapes.

[0109] In the embodiment of [Fig. 1], the two thermoelectric elements (11, 12) of the thermoelectric units (15) are identical in shape. The invention is not limited to thermoelectric elements (11, 12) of identical shape. These could have different shapes or be identical but arranged head-to-tail, as will be seen later.

[0110] The thermoelectric elements (11, 12) are each in the form of an elongated pad along a longitudinal axis, corresponding to a radial axis of the substrate (20), and are symmetrical with respect to this longitudinal axis. The thermoelectric elements (11, 12) increase in width along the longitudinal axis from their base to their apex. In cross-section, they exhibit straight lateral walls (34) extending radially from the substrate (20). This helps to limit the void spaces between the thermoelectric elements (31, 32). The thermoelectric elements can be made of thermoelectric materials such as silicon (Si), a silicon-germanium alloy (SiGe), bismuth telluride (Bi2Te3), skutterudites, a Half Heusler alloy, or lead telluride.

[0111] The internal electrical junctions (31) are here metallic tracks arranged at the top of the thermoelectric elements formed by a discontinuous metallic layer deposited on the thermoelectric elements (11, 12).

[0112] The external electrical junctions (32) are here metallic tracks arranged on the substrate (20) formed by a discontinuous metallic layer deposited on the substrate (20).

[0113] In this embodiment, the thermoelectric elements (11, 12) are connected in series, each thermoelectric element (11, 12), with the exception of the first and last thermoelectric elements in the series, being connected at its base to an adjacent thermoelectric element by one of the electrical connections (32) and at its apex to another adjacent thermoelectric element by one of the electrical connections (31). The first and last thermoelectric elements in the series are each connected to an adjacent thermoelectric element by one of their bases and apexes and to an external electrical connector, not shown, by the other of their bases and apexes.The thermoelectric elements (11, 12) can be arranged in circumferential rows in which the thermoelectric elements are electrically connected to each other by the internal and external electrical junctions (31, 32), two thermoelectric elements (11a, 12a) of each circumferential row being electrically connected to a thermoelectric element nearest to a front row and a back row along the longitudinal axis of the substrate respectively, with the exception of the first and last circumferential rows which are each connected to an electrical connector.

[0114] Figure 2 illustrates a method for manufacturing a variant of a thermoelectric module (10). The thermoelectric module (10) formed is similar to that of Figure 1. The only differences are that the substrate (20) is hexagonal in cross-section and not circular as in Figure 1, and that the thermoelectric elements (11, 12) are parallelepiped-shaped and therefore of constant width along their entire height. Each face (22) of the substrate carries one or more thermoelectric units (15), here two thermoelectric units (15). The thermoelectric units (15) with different bases are connected to each other by external junctions (32) at their base in the form of metallic tracks extending between the two corresponding faces. In this embodiment, the thermoelectric units are each located on one face. Nevertheless, it is possible, without going out of the scope of this invention, to have one or more thermoelectric units (15) straddling two adjacent faces.

[0115] In this manufacturing process, the first step (100) consists of providing the substrate (20) onto which the metallic tracks (32) forming the external electrical junctions are deposited in a second step (110). The deposition of the metallic tracks can be carried out in one or more layers by any deposition method.

[0116] The thermoelectric elements (11, 12) are then deposited in step (120) onto the metal tracks (32). The deposition of the thermoelectric elements (11, 12) is carried out by a concentrated energy deposition method using a suitable device.

[0117] The concentrated energy deposition device may comprise a plurality of nozzles, at least one or more of the first nozzles being connected to a reservoir of powder in a p-doped material and one or more second nozzles being connected to a reservoir of n-doped powder. The deposition of the thermoelectric elements (11, 12) can then be carried out by successive deposition of adjacent thermoelectric elements (11, 12) onto the metal tracks (32). The first nozzle(s) can then project the p-doped material to form a thermoelectric element (11), then the second first nozzle(s) can project the n-doped material to form an adjacent thermoelectric element (12), for example, of the same thermoelectric unit (15) or of the adjacent thermoelectric unit (15), and so on until all the thermoelectric elements (11, 12) are formed.Alternatively, the deposition step involves depositing all the thermoelectric elements of one doping and then depositing all the thermoelectric elements of the other doping.

[0118] Alternatively, the concentrated energy deposition device comprises a single nozzle or all of its nozzles are connected to one or more reservoirs containing a doped material. The deposition process is then similar to that described above, except that the reservoir(s) and / or the contents of the reservoir(s) must be changed in order to depose the thermoelectric elements of both dopings.

[0119] Finally in step 130, the metallic tracks (31) are deposited on the thermoelectric elements (11,12) to connect the thermoelectric elements to each other at their vertices, in this case to connect the thermoelectric units (15) to each other.

[0120] The process may include, after the formation of the thermoelectric units (11, 12), an additional annealing step not shown. The annealing step may include heating the formed module to a temperature greater than or equal to 100°C in a furnace under an inert atmosphere, in particular under an Argon atmosphere.

[0121] The thermoelectric module (10) of [Fig. 3] differs from the previous modules illustrated in that the substrate (20) is planar. The thermoelectric elements are also parallelepiped-shaped.

[0122] The invention is not limited to a particular shape of the thermoelectric elements (11, 12). Numerous variations of shapes can be envisaged. Figure 4 shows some of them. On the upper line, from a to i, the shapes correspond to thermoelectric elements deposited on a flat surface of the substrate (20), and on the lower line, from j to q, to ​​thermoelectric elements deposited on a curved surface of the substrate (20). However, the shapes of the upper line are adapted for deposition on a curved surface by means of adapting the base, and the shapes of the lower line are adapted for deposition on a flat surface by means of a few minor adaptations within the grasp of a person skilled in the art. The thermoelectric elements preferably extend along a longitudinal axis (X). The thermoelectric elements a, b, e, i are symmetrical with respect to their median plane perpendicular to their longitudinal axis (X).Thermoelectric elements c, d, f, and g are not symmetrical with respect to their median plane (Y), which is perpendicular to the longitudinal axis X. Thermoelectric element b has lateral recesses of thickness v and depth w. Thermoelectric elements c and d each have different surface areas at their base and apex. Thermoelectric elements c and d are complementary in shape and can be alternately aligned to bring the thermoelectric elements closer together. Thermoelectric element e has a lateral width between its apex and base that is less than the combined width of its apex and base, giving it an hourglass shape. Thermoelectric elements f, g, and i have branches extending towards the base for element f, towards the apex for element g, and towards both the apex and base for element i, forming an X shape.

[0123] The thermoelectric elements i, j, k, l, m, n, o, p, q correspond to the elements a, b, c, d, e, f, g, h, adapted to a contact surface of the curved substrate on which they are deposited. In this case, the substrate has a curved surface and the thermoelectric elements preferably have the same radius of curvature at their base and apex as the substrate.

[0124] Figure 5 illustrates a thermoelectric module (10) with a flat substrate surface (20). The differently doped thermoelectric elements (11, 12) are of different shapes. Each thermoelectric unit (15) comprises one trapezoidal thermoelectric element (11) with its longer side forming the base and one trapezoidal thermoelectric element (11) with its longer side forming the apex. The two thermoelectric elements (11, 12) have complementary lateral surfaces. All the thermoelectric units (15) can be identical.

[0125] The thermoelectric module of [Fig. 6] differs from that of [Fig. 1] in that the thermoelectric elements (11, 12) of each thermoelectric unit (15) have The thermoelectric elements are arranged along axes of different elongation than radial elongation, forming an angle α between them of between 5° and 70°. The angle α is approximately equal to 360 / n, where n is the number of thermoelectric units arranged around a cross-section of the substrate, here approximately equal to 45°. The connections can be made by metallic tracks or, as illustrated in the figure, by contact between adjacent thermoelectric elements (11, 12). In this case, the contact area (17) between the thermoelectric elements is preferably greater than or equal to 50% of the cross-section of a thermoelectric element. Each thermoelectric element can form an angle θ with the radial axis at its base that is approximately equal to the angle α. In the illustrated example, all the thermoelectric elements form the same angle with the radial axis.However, it could be otherwise; in particular, the thermoelectric elements of one doping could form a first angle, and the thermoelectric elements of the other doping could form a second angle different from the first with their radial axis. In this embodiment, the thermoelectric elements are connected to each other by contact at their base and their apex. Nevertheless, they could be connected by contact only at their base or only at their apex, the other connection being made by metallic tracks.

[0126] In [Fig. 6], the thermoelectric elements are connected to each other by contact. However, they could be connected to each other by a junction (40) formed of a mixture of p-doped material and n-doped material at their junction, as illustrated in [Fig. 7]. This junction (40) can be formed by using a concentrated energy deposition device comprising several nozzles connected to different reservoirs containing the p-doped material and the n-doped material respectively, and by simultaneously spraying the two materials at the junction between the two thermoelectric elements (11, 12).The manufacturing process can then comprise a sequence of projections coordinated with the movement of the nozzles on the substrate, involving a first projection of a material with a first doping level to form a first thermoelectric element (11) by the first nozzle(s), then a second projection of a material with a second doping level to form a second thermoelectric element (12) by the second nozzle(s), the first and second projections being simultaneous at the junction between the two thermoelectric elements (11, 12) to form the junction (40) by mixing the two materials. Preferably, the materials forming the thermoelectric elements are identical. Only their doping levels change.

[0127] Figure 8 illustrates a method for manufacturing a module (10), comprising supplying a substrate (20) according to step 100, then in step 105 depositing a support structure (25) onto the substrate (20), followed by deposition of the thermoelectric elements (11, 12) by deposition of concentrated energy in the same form as in [Fig. 6], that is, by contact junction or local mixing without a metallic track. The support structure (25) comprises support elements deposited at regular intervals on the substrate (20) which facilitate the fabrication of the thermoelectric elements inclined with respect to the radial axis by allowing their formation directly on the surface of these support structures (25). Preferably, the support structures (25) have a shape complementary to the spaces under the thermoelectric elements, in particular triangular. The support structure can be deposited by any known means. Preferably, such support elements can have a thermal conductivity less than or equal to that of the thermoelectric elements (11, 12), in particular made of an insulating material, for example, ceramic or silica, solid or porous.

[0128] Figure 9 illustrates a method for manufacturing a thermoelectric module (10) similar to that shown in Figure 8. In this embodiment, the support structure is formed of sacrificial elements (28) made of a sacrificial material. The method may then include a step 135 of removing the sacrificial material by a suitable method, in particular by chemical means or by heating. The sacrificial material may be ceramic or metal, in particular silica or aluminum nitride.

[0129] In the variant illustrated in [Fig. 10], the support structure comprises an inner part (28a) made of a sacrificial material and an outer part (28b) made of a non-sacrificial material. In step 105, the inner part (28a) made of sacrificial material is deposited onto the substrate (20), followed by a second deposit of a second material covering the sacrificial material (28b). In a subsequent step, the inner part (28a) of the support structure (25) is removed, leaving only the outer part (28b) of the support structure. The removal step may occur after the formation of the thermoelectric elements or later.

[0130] Figure 11 illustrates another method for manufacturing a variant of a thermoelectric module. The thermoelectric module (10) differs from that of Figure 6 in that each thermoelectric element (11, 12) is formed of a multilayer structure comprising, from base to top, a first layer (11i, 12i) of a first material deposited in step 120a by concentrated energy deposition as described previously, an interface (70) of a layer of one or more materials forming a diffusion barrier deposited by any means in step 125, in particular of copper or nickel, and a second layer (11ii, 12ii) of a second material deposited in step 120b by concentrated energy deposition as described previously. The invention is not limited to a multilayer structure comprising only two layers. A more complex structure is possible by successive depositions.

[0131] Figure 12 illustrates a variant of a thermoelectric module (10) wherein, in at least one thermoelectric unit (15b), the first thermoelectric element (11) and the second thermoelectric element (12) are each formed of two pads (11a, 11b; 12a, 12b) of the same doping. The two pads of Each element is electrically connected to itself on the substrate side and on the opposite side of the substrate in parallel. The thermoelectric elements (11, 12) of the thermoelectric units (15) are connected to each other on the opposite side of the substrate, here by electrical connections (31), and the thermoelectric units are connected to each other on the substrate side, here by electrical connections (32). The invention is not limited to one or two pads per thermoelectric element. The thermoelectric elements may have more than two pads depending on the desired performance and specifications. The invention is also not limited to the same number of pads for the two thermoelectric elements of the thermoelectric units. The first element could, for example, have a single pad and the second element could have two pads.

[0132] The invention is not limited to the examples just described. A person skilled in the art will be able to combine the lessons learned from the different embodiments to produce undescribed variants.

[0133] For example, the thermoelectric elements in Figures 1 and 2 can each be of a multilayer structure as described in relation to [Fig. 11].

Claims

Demands

1. A method for manufacturing a thermoelectric module (10) for generating a thermoelectric effect, comprising at least the steps of: a. Providing a substrate (20), b. Forming on the substrate (20) a plurality of thermoelectric units (15) each comprising two thermoelectric elements (11, 12) doped according to different types of doping, the two thermoelectric elements (11, 12) being electrically connected to each other on the side of the substrate (20) and / or on the side opposite the substrate (20), the two thermoelectric elements (11, 12) being at least partially formed by a concentrated energy deposition method.

2. Method of manufacturing a thermoelectric module (10) according to claim 1, the two thermoelectric elements (11, 12) of the same thermoelectric unit (15), being electrically connected by direct contact between them or by an internal electrical junction (31).

3. Method of manufacturing a thermoelectric module (10) according to claim 2, the internal electrical junctions (31) and / or external electrical junctions (32) being formed by the local deposition between the two thermoelectric elements (11, 12) of a layer of a mixture of the two materials composing the two thermoelectric elements or the deposition of a metallic track in contact with the two thermoelectric elements (11, 12).

4. Method of manufacturing a thermoelectric module (10) according to any one of the preceding claims, the thermoelectric elements (11, 12) being elongated along a longitudinal axis (X) and asymmetrical with respect to their median axis (Y) perpendicular to the longitudinal axis (X).

5. Method of manufacturing a thermoelectric module (10) according to any one of the preceding claims, the thermoelectric elements (11, 12) of the thermoelectric units (15) being of complementary shapes, in particular substantially interlocking with each other.

6. Method of manufacturing a thermoelectric module (10) according to any one of the preceding claims, the substrate (20) being cylindrical in shape with a polygonal base, in particular rectangular, square, pentagonal or hexagonal, circular or elliptical.

7. A method for manufacturing a thermoelectric module (10) according to any one of the preceding claims, comprising the deposition of a support structure on the substrate, the support structure (25) comprising support elements (25, 28) configured to extend between the thermoelectric elements (11, 12) and to serve as a support for the deposition of the thermoelectric elements during the deposition of the latter under concentrated energy, the support elements (25, 28) comprising in particular an electrically insulating material and / or a sacrificial material (28).

8. A method for manufacturing a thermoelectric module (10) according to any one of the preceding claims, the deposition under concentrated energy being carried out using a device comprising a plurality of nozzles for projecting material to be deposited, at least one or more first nozzles being connected to one or more reservoirs containing a doped material of type n to form one of the thermoelectric elements of each thermoelectric unit (15) at least in part and at least one or more other second nozzles being connected to one or more reservoirs containing a doped material of type p to form the other of the thermoelectric elements of each thermoelectric unit at least in part.

9. Method of manufacturing a thermoelectric module (10) according to the preceding claim, the formation of the thermoelectric units (15) at least in part is done by the alternating deposition of a p-type doped material and an n-type doped material for each thermoelectric unit (15) by alternating the projection of material by the first nozzle(s) and the second nozzle(s).

10. Method of manufacturing a thermoelectric module (10) according to claim 8 by its connection to claim 3, the internal (31) and / or external (32) electrical junctions can be formed by the local deposition between the two thermoelectric elements (11, 12) of a layer of a mixture of the two materials composing the two thermoelectric elements (11, 12), in particular carried out by deposition under concentrated energy, in particular by the simultaneous deposition of the two materials of different doping by the first or the second nozzle(s).

11. Method of manufacturing a thermoelectric module (10) according to the preceding claim, the thermoelectric elements (11, 12) are inclined on the substrate (20) with respect to the axis perpendicular to the substrate at their base in opposite directions, in particular at an angle α between 5° and 70°, the angle being able to depend on the expected thermoelectric performance, the required mechanical strength, the materials and / or the height of the elements.

12. Method of manufacturing a thermoelectric module (10) according to any one of the preceding claims, the thermoelectric elements (11, 12) comprising several layers of different materials doped with the same type of doping, in particular separated from each other by one or more interface structures (70).

13. A method for manufacturing a thermoelectric module (10) according to the preceding claim in relation to claim 3, comprising: a. the deposition under concentrated energy of the base of the thermoelectric elements (lli, 12i) in a first material with optionally the internal or external junctions at the base on the support or on conductive tracks, b. the deposition by any suitable method of the interface structure (70) on the parts of the thermoelectric elements formed and then c. the deposition by concentrated energy of the top of the thermoelectric elements (1 lii, 12ii) in a second material different from the first with optionally the internal (31) or external (32) junctions at the top of the thermoelectric elements.

14. A method of manufacturing a thermoelectric module (10) according to any one of the preceding claims, the module forming a thermoelectric circuit between a first thermoelectric element and a last thermoelectric element, the first and last thermoelectric elements being electrically connected by one of their ends to an electrical connector and the thermoelectric elements between the first and last thermoelectric elements being all electrically connected to at least two adjacent thermoelectric elements to form the thermoelectric circuit between them.

15. A method for manufacturing a thermoelectric module (10) according to any one of the preceding claims, the first element and the second element of a thermoelectric unit (15) being electrically connected in series with each other on one side of the substrate and on the opposite side of the substrate only.

16. Method of manufacturing a thermoelectric module (10) according to any one of claims 1 to 14, the first and second elements of a thermoelectric unit (15) being electrically connected in parallel with each other on the substrate side and on the side opposite the substrate.

17. Thermoelectric module (10) manufactured by the manufacturing process according to any one of the preceding claims.

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