Feedthrough for forming a terminal for an electrochemical metal-ion battery and corresponding battery

Description

Technical field

[0001] The present invention relates to a terminal-forming feedthrough for a metal-ion electrochemical accumulator, and to such an accumulator.

[0002] The invention relates more particularly to a high-capacity lithium-ion (Li-ion) electrochemical accumulator, typically greater than 10 Ampere-hours (Ah), and having the ability to pass high currents, typically greater than 100 A.

[0003] The invention relates more particularly to the production of a crossing of a case to enable the high-capacity Li-ion accumulator equipped with it to be able to deliver high currents.

[0004] By "crossing", we specify that we mean the usual meaning, that is to say a device used to pass an electrically conductive element through a wall and insulating the conductor from this wall.

[0005] Although described with reference to a Lithium-ion accumulator, the invention applies to any metal-ion electrochemical accumulator, i.e. also Sodium-ion, Magnesium-ion, Aluminum-ion, etc. Prior art

[0006] A lithium-ion battery or accumulator usually comprises at least one electrochemical cell consisting of an electrolyte constituent between a positive electrode or cathode and a negative electrode or anode, a current collector connected to the cathode, a current collector connected to the anode and finally, a packaging arranged to contain the electrochemical cell in a sealed manner while being crossed by a part of the current collectors.

[0007] The electrolyte component may be in solid, liquid or gel form. In the latter form, the component may comprise a polymer or microporous composite separator soaked in organic or ionic liquid electrolyte(s) that allows the movement of the lithium ion from the cathode to the anode for charging and vice versa for discharging, thereby generating the current. The electrolyte is generally a mixture of organic solvents, for example carbonates to which a lithium salt, typically LiPF6, is added.

[0008] The positive electrode or cathode is made of Lithium cation insertion materials which are generally composite, such as LiFePO 4 , LiCoO 2 , LiNi 0.33 Mn 0.33 Co 0.33 O 2 .

[0009] The negative electrode or anode is very often made of graphite carbon or Li 4 TiO 5 O 12 (titanate material), possibly also based on silicon or a composite formed from silicon.

[0010] The current collector connected to the positive electrode is usually made of aluminum.

[0011] The current collector connected to the negative electrode is usually made of copper, nickel-plated copper, or aluminum.

[0012] A lithium-ion battery or accumulator can obviously comprise a plurality of electrochemical cells which are stacked on top of each other.

[0013] Traditionally, a Li-ion battery or accumulator uses a pair of materials at the anode and cathode allowing it to operate at a high voltage level, typically equal to 3.6 Volts.

[0014] A Li-ion battery or accumulator has rigid packaging when the intended applications are restrictive where a long service life is required, for example with much higher pressures to withstand and a stricter level of sealing required, typically less than 10 -8< mbar.1 / s, or in environments with high constraints such as the aeronautical or space sectors.

[0015] Also, to date, rigid packaging consists of a metal case, typically made of stainless steel (316L or 304 stainless steel), aluminum (A1 1050 or Al 3003) or titanium.

[0016] Currently, two types of hard case are manufactured.

[0017] The first type consists of a rigid case consisting of a machined bottom and a cover welded together on their periphery by laser. The current collectors are partly made of metal wires or pins. The pin(s) is (are) welded by electric welding or ultrasonic welding to the part of the corresponding current collector itself connected to one of the electrodes of an electrochemical cell or a stack of electrochemical cells. To achieve electrical insulation between the metal cover of the case and the metal pin, a glass ball sends the pin, thus constituting what is commonly called a glass-to-metal (TVM) feedthrough. In addition, to achieve sealing with the cover of the case, a ring around the glass ball and generally in the same metal as that of the case is welded to the latter.Some configurations plan to use a single TVM, the box constituting the other terminal also called the accumulator pole.

[0018] The second type also consists of a rigid case made with a stamped cup and a cover welded together on their periphery by laser. On the other hand, current collectors include a feedthrough with a part protruding on the top of the case and which forms a terminal also called the exposed pole of the battery.

[0019] A first example of assembly of such a crossing 1 forming a terminal with the current collector 2 and with the cover 3 of a box is shown in Figure 1: the collector 2, typically made of copper in the form of an internally threaded male part, is fixed by screwing using a nut 2 of type M5 or M8. Two washers 5A, 5B made of electrically insulating material, typically polypropylene, superimposed on each other, are interposed, one 5A between the cover 3 and the other washer 6 supporting the nut 4 and the other 5B between the cover 3 and the collector 2. These washers 5A, 5B provide the sealing and electrical insulation of the collector 2 with respect to the housing cover 3. More precisely, in this first illustrated example, the two insulating washers 5A, 5B are identical and each comprise a support portion 50A, 50B and a guide and centering portion 51A, 51B. The support portion 50A is in surface support with pressure both against the face 30 of the wall of the cover 3 and against the support washer 6 of the nut 4.Similarly, the support portion 50B bears surface-wise against both the opposite face 31 of the cover 3 and against the support portion 20 of the current collector 2. The guide and centering portions 51A, 51B are, for their part, in contact both against the edge of the through-orifice 32 of the cover 3 and against the collector 2. These guide and centering portions 51A, 51B make it possible to guide and center both the washers 5A, 5B in the through-orifice 32 and the male collector 2 in said washers 5A, 5B.

[0020] A second example of assembly of a bushing 1 forming a terminal with the current collector 2 and with the cover 3 of a box is shown in Figure 2: the collector 2, typically made of copper, in the form of an internally threaded male part is fixed by crimping the collector onto the support washer 6. Here we also find the two washers 5A, 5B made of electrically insulating material, with their support portions 50A, 50B and their guide and centering portions 51A, 51B which are arranged identically and perform the same functions as in the first example. On the other hand, the fixing by crimping according to this second example is done without using an additional part, such as the screw nut 4 of the first example. Indeed, the crimping is carried out by mechanical crushing of a crimping portion 21 arranged on the outside of the cylindrical part of the collector 2, against the support washer 6.

[0021] A third example of assembly of a terminal-forming bushing with the current collector and with the cover of a box is described in patent application FR 2798227.

[0022] As mentioned previously, a Li-ion battery or accumulator uses a pair of materials at the anode and cathode allowing it to operate at a high voltage level, typically equal to 3.6 Volts.

[0023] Other material pairs are possible and deliver a lower voltage level. For example, a LiFePO 4 / graphite material pair delivers an average operating voltage level of between 3.0 and 3.2 Volts. Also for example, a LiFePO 4 / Li 4 TiO 5 O 12 material pair delivers an average operating voltage level of between 1.6 and 1.8 Volts.

[0024] The solution proposed in the aforementioned application FR 2798227 is not suitable for the passage of high currents, because doing so would amount to causing a loss of contact by decohesion between the male part and the female part during heating, causing thermal expansion, in particular due to the geometries of said parts and the absence of laser welding...

[0025] This is why the applicant proposed in patent application FR 2989836, a Li-ion accumulator equipped with a case with connection terminals allowing the passage of very high currents, typically greater than 100A, with average voltage levels lower than that traditionally used equal to 3.6 Volt. Indeed, for so-called power applications, a high-capacity accumulator must deliver very high power to its terminals, that is to say a very high product of the current by the voltage. However, due to the use of couples with lower voltage levels, it is necessary to deliver higher currents than traditionally used.

[0026] We have represented in Figure 3 , an example of a crossing forming terminal 1 of a Li-ion accumulator, according to application FR 2989836.

[0027] The crossing 1 is made through an orifice 32 opening on either side of a cover 3 of a Li-ion accumulator case. This cover has two opposite faces 30, 31. The crossing 1 extends along an axis X parallel to the axis of the Li-ion accumulator case.

[0028] The feedthrough 1 firstly comprises two identical electrically insulating washers 5A, 5B. Each washer comprises a bearing portion 50A, 50B and a guide portion 51A, 51B projecting from the bearing portion. The bearing portion of the upper washer 5A bears on its surface with pressure against the upper face 30 of the cover 3 and its guide portion 51A is in contact with the edge of the orifice 32 of the cover 3. Similarly, the bearing portion of the lower washer 5B bears on its surface with pressure against the lower face 30 of the cover 3 and its guide portion 51B is in contact with the edge of the orifice 32 of the cover 3.

[0029] The crossing 1 comprises an electrically conductive male part 7 tightly fitted into an equally conductive female part 8. The female part 8 is open-ended.

[0030] Each of the male 7 and female parts comprises a bearing portion 70, 80. The bearing portion 70 of the male part 7 is in surface bearing with pressure against the bearing portion 50A of the upper washer 5A, while the bearing portion 80 of the female part is in surface bearing with pressure against the bearing portion 50B of the lower washer 5B. As illustrated in Figure 3 , the female part 8 is furthermore in surface support with pressure linked to its deformation against the guide portions 51A, 51B of the washers.

[0031] According to this application FR 2989836, the material(s) of the male 7 and female 8 parts is (are) chosen and their sections dimensioned so as to allow the passage of an electric current of value at least equal to 100A, which can be a direct current for a duration of at least 3 minutes. On the Figure 3 , the black arrowed path symbolizes the path of a current I greater than 100A through crossing 1 according to application FR 2989836.

[0032] Generally, the conductive parts of a sealed feedthrough or terminal implemented in known Li-ion accumulators, in particular in the aforementioned patent applications, are made of nickel-plated copper. This is due to the fact that such a feedthrough serves as the negative terminal of the accumulator and is therefore electrically connected to the negative electrode, which very often comprises graphite as an active insertion material, graphite generally supported by coating on a copper foil. In other words, the nickel-plated copper of the conductive parts of the terminal is the most compatible material with the copper foil of the negative electrode.

[0033] However, new generation metal-ion accumulators involve the use of new types of active insertion materials, such as silicon, titanate or sodium. Not only can these materials be satisfactorily coated on an aluminum substrate, such as an aluminum strip, but also, the selection of the purest possible grade of aluminum inside the accumulator makes it possible to avoid, with these materials, the presence of pollution and the generation of galvanic couples in the presence of the electrolyte, which can lead to corrosion.

[0034] The inventors were thus faced with the need to define a feedthrough for an accumulator whose conductive parts had at least one part made of aluminum in order to allow the best compatibility with an aluminum substrate, as a support, of new types of active insertion materials, such as silicon, titanate or sodium.

[0035] They naturally turned to the solution according to request FR 2989836, using male and female aluminum parts.

[0036] However, under certain conditions of assembly tests by crimping between these parts, they have shown that significant deformations of the base of the female part could appear, with in particular a pronounced increase in the diameter of the base of the female part linked to the plasticity of the aluminum under the pressure exerted at the crimping stage between the male and female parts.

[0037] JP2000138055 discloses a battery feedthrough having a positive electrode terminal having a male part screwed into a female part.

[0038] US2006 / 292442 also discloses a screw connection between the male and female parts of a bushing.

[0039] US2012 / 058390 discloses an electrochemical accumulator feedthrough through an orifice in the cover comprising a male part which fits forcefully into a conductive female part, without opening out.

[0040] WO2017 / 141694 discloses a battery feedthrough comprising a male part 230 inserted into a female part 205, the male part being the one inside the housing

[0041] JP H07235289 discloses a terminal comprising a male part deformed during assembly in a female part comprising a blind hole. There is therefore a need to improve the production of a sealed feedthrough forming a terminal for a metal-ion electrochemical accumulator, through a housing of the accumulator, in particular with a view to having at least a portion of the conductive parts of the feedthrough, in aluminum, in order to be able to use other active insertion materials for the electrode(s), in particular negative electrode(s) of the accumulator, such as silicon, titanate or sodium, which can be supported by an aluminum substrate. Statement of the invention

[0042] To this end, the invention relates, in one of its aspects, to a feedthrough forming a terminal for a lithium-ion (Li-ion) electrochemical accumulator, according to claim 1. This feedthrough, produced through an orifice opening out on either side of a wall comprising two opposite faces, comprises an electrically conductive male part and a female part made of an aluminum-based alloy, a portion of the male part being tightly fitted into a blind hole in the female part.

[0043] By "aluminium-based alloy" is meant an alloy comprising a very large majority of aluminium, with, where appropriate, other elements in small proportions, such as Si, Mn, Zn, Fe, Ti, typically less than 0.5%.

[0044] According to an advantageous embodiment, the crossing comprises: two electrically insulating washers, each comprising a surface support portion bearing against one of the faces of the wall and a guide portion projecting from the support portion and in contact with the edge of the orifice, crossing in which each of the conductive parts comprises a support portion in surface support against a support portion of the washers.

[0045] Insulating washers can be made of polyetherimide (PEI).

[0046] According to a particularly advantageous embodiment, the male part is made of an aluminum-based alloy different from that of the female part.

[0047] According to this embodiment, preferably, the aluminum alloy of the male part is chosen from a grade 5754, 6060 or 3003 with a work-hardened state H18, while the aluminum alloy of the female part is a grade 1050.

[0048] Thus, according to the invention, it is advantageous to propose a feedthrough with a pair of male and female parts, both made of aluminum alloy but which are distinct in order to respond in an adapted and differentiated manner to the constraints to which the parts are subjected. The male part is therefore made of an aluminum alloy which has very good mechanical characteristics while the aluminum alloy of the female part is chosen for its chemical compatibility with the electrochemical core of a metal-ion accumulator.

[0049] For the male part, a grade 5754, a grade 6060 or a grade 3003 with a work-hardened state H18 has very good mechanical characteristics and remains intact when pressure is applied to its surface, in particular during crimping according to the invention. Among these very good mechanical properties, there is the high breaking strength which makes it possible to apply a screw tightening torque between the male part of the feedthrough and a busbar at a level equivalent to or even higher than that applicable on a copper-based terminal according to the state of the art. Typically; the screw tightening torque which can be applied to an output terminal according to the invention is greater than 4 Nm

[0050] In addition, grades 5754 and 6060 are directly compatible with a grade of 1050 aluminum for the female part, in order to ensure continuous electrical conduction, with low electrical resistivity and relatively close to that of grade 1050.

[0051] For a 3003 grade with a H 18 hardened state, the Mg content can advantageously be between 0.01 and 0.05%, and the copper (Cu) content between 0.05 and 0.2%.

[0052] For a 5754 grade, the Mg content can advantageously be between 2.6 and 3.2% and the copper (Cu) content between 0.05 and 0.1%.

[0053] For a 6060 grade, the Mg content can advantageously be between 0.35 and 0.6% and the copper (Cu) content between 0.05 and 0.1%.

[0054] As for the female part, a 1050 grade is perfectly compatible with the materials that can constitute the electrochemical core of a metal-ion accumulator, including active insertion materials based on silicon, titanate or sodium, an electrolyte based on LiPF6 for a Li-ion accumulator... In addition, this grade of aluminum is similar to that usually used for current collectors and aluminum-based electrode strips.

[0055] In other words, according to the invention, the same type of crossing is produced as that according to patent application FR 2989836, with in addition the tight fit between a projecting portion of the male part and a blind hole of the female part which is made of aluminum, preferably in the purest possible grade of aluminum.

[0056] Making a blind hole in the female part instead of a through hole as in application FR 2989836 makes it possible to mechanically reinforce the female part, which avoids any unwanted deformation during crimping, and therefore ultimately makes it possible to obtain a robust crossing.

[0057] By means of the invention, a metal-ion accumulator can be defined with any insert material supported by an aluminum strip which is electrically connected to the female part made of aluminum-based alloy of the terminal according to the invention.

[0058] The invention firstly guarantees a sealed, mechanically robust crossing, that is to say, which has the following characteristics: it does not deform during the assembly stages of the accumulator, it supports a tightening torque (generally greater than 3N.m) which can allow the assembly of the accumulator with other accumulators in the form of a module by means of assembly bars, of the "busbar" type; it can remain intact throughout the lifetime of an accumulator in its application, and therefore withstand vibrations, mechanical shocks, temperature variations, typically between - 40°C and +75°C, and pressure, without parasitic deformation and without leakage.

[0059] Furthermore, the base of the female part being solid, the male part is no longer in direct contact with the internal elements of the accumulator which participate in the electrochemistry of the latter, the perfect seal being moreover ensured between the female part and the wall of the accumulator which supports the crossing by means of the lower insulating washer.

[0060] By "perfect sealing" we mean sealing according to one of the strictest levels required, typically less than 10 -8< mbar.1 / s for helium.

[0061] Preferably, the tight fit of the portion of the female part in the blind hole of the female part is an N9p7 type fit, in particular for a bore diameter of the blind hole of the order of 6 mm. It is specified here that the fit considered N9p7 is that according to the ISO system of fits.

[0062] Advantageously, the material(s) of the parts can be adapted and their sections dimensioned so as to allow the passage of an electric current up to a value at least equal to 100A.

[0063] According to an advantageous embodiment, the portion of the male part comprises at least one conduit opening both outside the accumulator and on the bottom of the blind hole of the female part, so as to evacuate the air during assembly by crimping the male part in the female part.

[0064] This method is advantageous because under certain crimping conditions, the inventors were able to observe that a non-compressible volume of air could remain, corresponding to a chamber located between the end of the male part and the bottom of the blind hole in the female part.

[0065] However, the presence of this chamber can have the effect of preventing complete tightening. Thus, the conduit opening into the male part allows the air to be completely evacuated during crimping, the portion of the male part being able to reach the mechanical stop against the bottom of the blind hole of the female part. Ultimately, the presence of the conduit makes it possible to more precisely adjust the insertion stroke of the male part into the female part and therefore to minimize the play between them, after crimping. This has the effect of better controlling the crimping force to be implemented and of reinforcing the quality of the tightening obtained between the two parts.

[0066] The through conduit can advantageously be made in the continuity of a central tapped hole of the male part. The conduit can be made by drilling 1 to 2 mm in diameter during the machining of this male part.

[0067] According to another embodiment, the male part is made of copper-based alloy, preferably electrolytic copper CuA1 or nickel-plated copper.

[0068] Nickel-plated copper has the advantage of being of the same chemical nature as that defined for a conventional copper negative terminal, which can allow an identical interface to be maintained with respect to a user, even if the electrochemistry of the accumulator is different from conventional electrochemistry.

[0069] The invention also relates, in yet another aspect, to a metal-ion battery or accumulator, comprising a housing with a cover through which a passage as described above is made.

[0070] According to one feature, the male part is of the internally threaded type and projects outward from the housing.

[0071] The cover can be made of aluminum, such as 1050 or 3003 aluminum.

[0072] According to an advantageous configuration, the female part of the feedthrough is welded to an aluminum-based current collector itself welded to an aluminum-based electrode strip supporting an active material for inserting metal ions, preferably chosen from a titanate-based material, such as lithium titanate oxide Li 4 TiO 5 O 12 , a silicon-based material, a sodium-based material.

[0073] The invention finally relates to a method for producing a crossing as described above, according to which the steps of claim 12 are carried out. These steps include the following: a / insertion through the orifice, from each of the two opposite faces of the wall, of one of the guide portions of the washers, so that they are in abutment against the edge of the orifice of the wall, b / insertion, from one face of the wall, of the female aluminum part into one of the washers; c / force fitting, from the opposite face of the wall, of the male part, so that the portion of the male part is in abutment against the bottom of the blind hole of the female part, each of the support portions of the male and female parts is in abutment with pressure against a support portion of the washers itself guided against the edge of the orifice.

[0074] The force fitting making it possible to obtain the supports with pressure, according to step c / is advantageously carried out under pressure with a force greater than or equal to 1 tonne-force so as to obtain an adjustment of type N9p7 between portion of male part and blind hole of female part, in particular for a bore diameter of the blind hole of the female part of the order of 6mm. Detailed description

[0075] Other advantages and characteristics of the invention will become more apparent upon reading the detailed description of examples of implementation of the invention given for illustrative and non-limiting purposes with reference to the following figures, among which: there Figure 1 is an axial sectional view of a feedthrough forming a terminal of a Li-ion accumulator according to an example of the state of the art; Figure 2 is an axial sectional view of a feedthrough forming a terminal of a Li-ion accumulator according to another example of the state of the art; Figure 3is an axial sectional and perspective view of a feedthrough forming a terminal of a Li-ion accumulator according to yet another example of the state of the art; Figure 4 is an axial sectional view of the Figure 3 ; there Figure 5 is an axial sectional view of a state-of-the-art Li-ion battery cover through which the crossing is made according to the figures 3 And 4 , as a negative terminal, the positive terminal being soldered directly onto the cover; Figure 6 is an axial sectional view of a terminal-forming feedthrough of a metal-ion accumulator according to a first example of the invention; Figure 7 is an axial sectional view of a metal-ion accumulator cover according to the invention through which the passage is made according to the Figure 6 , as a negative terminal, the positive terminal being soldered directly onto the cover; figure 8is a reproduction of a cross-sectional photograph of a crossing according to the invention according to the Figure 6 with the male part made of 5754 aluminum and the female part of 1050 aluminum; the Figure 9 is a reproduction of a cross-sectional photograph of a crossing according to the invention according to the Figure 6 with the male part made of Cu A1 copper and the female part of 1050 aluminum; the Figure 10 is an axial sectional view of a feedthrough forming a terminal of a metal-ion accumulator according to a second example of the invention; Figure 11 is an axial sectional view of the male part of the terminal according to the Figure 10 ; there Figure 12 is a reproduction of a cross-sectional photograph of a crossing according to the invention according to the Figure 6 with the male part made of Cu A1 copper and the female part of 1050 aluminum; the Figure 13 is a reproduction of a cross-sectional photograph of a crossing according to the invention according to the Figure 10with the male part made of Cu A1 copper and the female part of 1050 aluminum; the Figures 14A and 14B are perspective views respectively from above and below of a cover with a circular section intended to be fixed on a case of a metal-ion accumulator, the cover integrating a sealed feedthrough according to the invention, as an output terminal of one polarity; the Figure 15 is a perspective view of a cylindrical metal-ion accumulator case, with a cover through which a terminal-forming feedthrough according to the invention is made; figure 16 is a perspective view of a prismatically shaped metal-ion accumulator case, with a cover through which a terminal-forming feedthrough according to the invention is made.

[0076] THE figures 1 to 5 relate to three different examples of a feedthrough forming a Li-ion battery terminal according to the state of the art. These figures 1 to 5have already been commented on in the preamble and are therefore not commented on further below.

[0077] For the sake of clarity, the same references designating the same crossing elements according to the state of the art and according to the invention are used for all figures 1 to 16 .

[0078] Throughout this application, the terms "lower", "upper", "bottom", "top", "below" and "above" are to be understood by reference to a metal-ion battery case positioned vertically with its cover on top and the feedthrough projecting upwardly outside the case.

[0079] We have represented in Figure 6 , a first example of a crossing forming terminal 1 of a metal-ion accumulator, according to the invention.

[0080] The crossing 1 according to the invention includes all the components of the crossing according to the state of the art, detailed in the preamble and shown in Figure 4, with the following additional features: the female part 8 is made of grade 1050 aluminum; the tight fit is made between the projecting portion 71 of the male part 7 and the blind hole 81 of the female part 8.

[0081] Thus, the base of the female part 8 is solid, which not only increases the mechanical resistance of the terminal under the effect of the crimping pressure, but also removes any direct physical contact between the male part 7 and the materials carrying out the electrochemistry of the accumulator, which are the active insertion materials and the electrolyte.

[0082] The inventors carried out various crimping tests by increasing the thickness E of the base of the female part 8 of the terminal according to the invention.

[0083] They were able to observe that with a tight fit of type N9p7, that is to say for a portion 71 of the male part with a diameter equal to 6mm +5µm / +30µm and a blind hole 81 of the female part with a bore diameter D of the order of 6mm -25µm / 0µm, a thickness E of a value greater than or equal to 2mm allows the crossing 1 to withstand a significant crimping force, typically of the order of 1.5 tonnes, without mechanical deformation of the parts 7, 8.

[0084] By definition, the value of the thickness E of the base of the female part is all the more important as the bore diameter D is high because the more this diameter increases, the greater the crimping force must be.

[0085] Another important feature to ensure a robust mechanical connection between male part 7 and female part 8, after crimping is the height H of the portion of the blind hole 71 of the female part 8 in which the portion 71 of the male part 7 is tightly fitted.

[0086] Thus, the inventors also carried out different press tests with different forces applied for the force fitting by increasing the value of the height H with that of the bore diameter D of the blind hole 81.

[0087] The conditions and results of these tests are shown in the table below. Diameter D in mm 4 à 5 6 7 à 8 Height H in mm 1,4 à 1,7 1,8 à 2,2 2,2 à 2,6 Thickness E in mm ~ 1 ~ 2 ~ 3 Crimping force in tons ~ 1,0 ~ 1,5 2 à 2,5

[0088] To carry out a crossing according to the first example according to the invention, the following steps are carried out.

[0089] One of the guide portions 51A, 51B of the washers 5A, 5B is inserted through the orifice 32, from each of the two faces 30, 31 of the cover 3, so that they bear against the edge of the orifice 32.

[0090] From the lower face 31 of the cover 3, the female part 8 is inserted into the lower washer 5B.

[0091] The male part 7 is force-fitted from the upper face 30 opposite the lower face 31 of the cover 3. The force-fitting makes it possible to tightly adjust the projecting portion 71 of the male part 7 in the blind hole 81 of the female part 8 and to have each of the bearing portions 70, 80 of the male 7 and female 8 parts in surface support with pressure against a bearing portion 50A, 50B of the washers 5A, 5B themselves guided by the edge of the orifice 32.

[0092] Cross-sections according to the first example of the invention have been made. The figure 8 is a photographic reproduction of a section with a male part 7 in grade 5754 aluminum and a female part 8 in grade 1050 aluminum, while the Figure 9 shows a crossing with a male part 7 in Cu A1 copper and a female part 8 in grade 1050 aluminum.

[0093] As visible in these sections, there remains a non-compressible volume of air V corresponding to a chamber located between the end of the portion 71 of the male part and the bottom 82 of the blind hole 81 of the female part 8.

[0094] In order to eliminate this chamber which can have the effect of preventing complete tightening, the inventors have made a crossing 1 by drilling, in the continuity of the threaded part 72 of the male part 7, an additional opening conduit 73. This conduit 73 shown schematically in Figures 10 and 11 thus allows air to be evacuated when crimping the male part 7 into the female part 8.

[0095] In order to check the effectiveness of the additional outlet duct 73, a section was made: it is shown in Figure 13on which it is clearly seen that the clearance between the lower end of the portion 71 of the male part 7 and the bottom 82 of the blind hole 81 is reduced to a minimum, which allows better control of the crimping force to be implemented and thus to reinforce the quality of the tightening obtained between the two parts 7, 8.

[0096] For comparison, the same crimping conditions were carried out for a crossing 1 with identical parts 7, 8, according to the first example of the invention, that is to say without the conduit 73: the crossing 1 is shown in Figure 12 . We again distinguish the presence of the incompressible volume V.

[0097] The crossing 1 according to the invention can be produced on a cover 3 of a metal-ion accumulator case 10 either according to a cylindrical geometry ( figures 14A, 14B , 15 ) than according to a prismatic geometry ( figure 16). In these different configurations, the terminal 1 according to the invention is for example negative, the positive terminal 11 being able to be produced, for example directly by welding, also on the cover 3.

[0098] Although not previously specified, it is ensured that the solid base of the female part 8 has a sufficient surface area to be able to electrically connect an internal connector to the housing and itself electrically connected to the electrochemical bundle usually called a coil, consisting of one or more electrochemical cells. The electrical connection between the internal aluminum-based connector and the solid base of the aluminum female part 8 can be made by welding.

[0099] The invention is not limited to the examples which have just been described; in particular, it is possible to combine characteristics of the examples illustrated within non-illustrated variants.

[0100] The expression "comprising a" should be understood as being synonymous with "comprising at least one", unless otherwise specified.

Claims

1. Feedthrough (1) forming a terminal for a metal-ion electrochemical accumulator, provided through an aperture (32) opening out on either side of a wall (3) including two opposite faces (30, 31), including: - an electrically conductive male part (7), and - a female part (8) made of an aluminum-based alloy, a portion (71) of the male part (7) being tight-fitted into a blind hole (81) of the female part (8), the male part (7) being made of an aluminum-based alloy that is different from that of the female part.

2. Feedthrough according to Claim 1, including: - two electrically insulating washers (5A, 5B), each including a bearing portion (50A, 50B) superficially bearing against one (30, 31) of the faces of the wall and a guide portion (51A, 51B) protruding with respect to the bearing portion and making contact with the edge of the aperture (32), in which feedthrough each of the conductive male and female parts includes a bearing portion (70, 80) superficially bearing against a bearing portion (50A, 50B) of the washers.

3. Feedthrough (1) according to Claim 1, the aluminum alloy of the male part being chosen from grade 5754, 6060 and 3003 alloys with an H18 temper, the aluminum alloy of the female part being a grade 1050 alloy.

4. Feedthrough according to one of the preceding claims, the tight fitting of the portion (71) of the male part (7) in the blind hole (81) of the female part is a type N9p7 fitting, in particular for a bore diameter of the blind hole (81) of the order of 6 mm.

5. Feedthrough (1) according to one of the preceding claims, the one or more materials of the parts and the dimensions of the cross sections of the parts being suitable for allowing an electric current up to a value that is at least equal to 100 A to pass.

6. Feedthrough (1) according to one of the preceding claims, the portion of the male part comprising at least one duct (73) opening out both on the outside of the accumulator and on the bottom of the blind hole of the female part, in such a way as to let air out when crimping the male part into the female part.

7. Feedthrough (1) according to one of the preceding claims, the thickness of the female part measured between the bottom (82) of the blind hole (81) and the base of the female part (8) being greater than or equal to 2 mm for a bore diameter of the blind hole of the order of 6 mm.

8. Metal-ion accumulator or battery including a housing (10) with a cover (3) through which a feedthrough (1) according to any one of Claims 1 to 7 is produced.

9. Metal-ion accumulator or battery according to Claim 8, the male part (7) being an internally threaded part and protruding toward the outside of the housing (10).

10. Metal-ion accumulator or battery according to Claim 8 or 9, the cover being made of aluminum, such as 1050 or 3003 aluminum.

11. Metal-ion accumulator or battery according to one of Claims 8 to 10, the female part of the feedthrough being welded to an aluminum-based current collector which is itself welded to an aluminum-based electrode foil bearing an active metal-ion insertion material, preferably chosen from a material based on titanate, such as lithium titanate oxide Li4TiO5O12, a silicon-based material or a sodium-based material.

12. Method for producing a feedthrough according to any one of Claims 2 to 7, with the exception of Claim 3, wherein the following steps are carried out: a / inserting, through the aperture (32), from each of the two opposite faces (30, 31) of the wall (3), one of the guide portions (51A, 51B) of the washers (5A, 5B) such that they bear against the edge of the aperture (32) in the wall; b / inserting, from one face (31) of the wall, the aluminum female part (8) into one of the washers (5B); c / press-fitting, from the opposite face (30) of the wall, the male part (7) such that the portion (71) of the male part (7) abuts against the bottom (82) of the blind hole (81) of the female part (8) and such that each of the bearing portions (70, 80) of the male and female parts superficially bears against a bearing portion (50A, 50B) of the washers that is itself guided against the edge of the aperture.

13. Method according to Claim 12, the press-fitting operation in step c / being carried out by pressing with a force that is greater than or equal to 1 tonne-force so as to obtain a type N9p7 fitting between portion (71) of male part (7) and blind hole (81) of female part (8), in particular for a bore diameter of the blind hole of the female part of the order of 6 mm.