CA3248239A1

CA3248239A1 - Method to produce a battery for energy storage

Info

Publication number: CA3248239A1
Application number: CA3248239A
Authority: CA
Inventors: Massimo Fortini; Giacomo Noferini
Original assignee: GD SpA
Priority date: 2022-02-03
Filing date: 2022-12-21
Publication date: 2023-08-10
Also published as: WO2023148550A1; EP4473605A1; US20250141069A1; KR20240144310A; JP2025504118A

Abstract

Method to produce an energy storage battery (1) having the steps of: providing an electrochemical cell (2), which is at least partially complete and is provided with an electrical collector (11); providing a container (3) having a first wall (8); placing, on an outer surface of the first wall (8), an outer body (17; 25), which constitutes an electrical pole (14) of the battery (1); and inserting the electrochemical cell (2) into the container (3) bringing the electrical collector (11) close to the first wall (8); providing the electrical collector (11) with an access (15; 22; 26) from the outside of the container (3) in order to permit a weld (24) between the electrical collector (11) and the outer body (17; 25) in order to establish an electrical connection; welding the electrical collector (11) and the outer body (17; 25) to one another through the aforementioned access (15; 22; 26) in order to establish an electrical connection.

Description

METHOD TO PRODUCE A BATTERY FOR ENERGY STORAGE DESCRIPTION TECHNICAL FIELD The present invention relates to a method to produce an energy storage battery, that is, more generally, to an energy storage device. The meaning of "to produce a battery" also refers to the assembly thereof. The present invention finds advantageous application to the production of a lithium-ion cylindrical battery, to which the following description will explicitly refer without thereby losing generality. BACKGROUND Commercial lithium-ion batteries are assembled in three different geometries: cylindrical, prismatic and bag-like. The cylindrical batteries are formed by a cylindrical metal container with inside a single electrochemical cell of the "jelly-roll" or "Swiss-roll” type, formed by an anode, separator and cathode which are wound together around a central pin. In particular, the cylindrical container is at first open on one side (i.e. it has the shape of a cup having a first end which is closed and a second end which is open) to allow the insertion of the wound electrochemical cell and of the electrolyte that impregnates the wound electrochemical cell; once the formation of the battery has been completed (i.e. once all the components have been arranged inside the cylindrical container), the open end of the cylindrical container is closed making a sealed closure. In particular, in order to close the open end of a cylindrical container, a circular lid (possibly coupled to an annular gasket) is used which is connected to the cylindrical container, deforming against the lid an upper rim of the cylindrical container itself. Before inserting the electrochemical cell inside the cylindrical container, at the two opposite ends of the electrochemical cell two electrical collectors are coupled (which in the particular case of the cylindrical batteries are disc-shaped) at the cathode (in which an electrical collector made of aluminium is used) and at the anode (in which an electrical collector made of copper is used). Each electrical collector is pressed against the corresponding end of the electrochemical cell and is welded to connection lamellae of the conductive strips (made of aluminium and copper) which, wound together (with the 15 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 interposition of insulating separators), constitute the electrochemical cell. The one first wall of the cylindrical container has centrally a through hole which is engaged by a rivet (also called rivet) made of aluminium having a head that is arranged on the outside of the cylindrical container and constitutes the positive pole of the cylindrical battery. In particular, the rivet is inserted through the through hole of the first wall of the cylindrical container with the interposition of a series of plastic gaskets that isolate the rivet from the cylindrical container and then the headless end of the rivet is bucked (i.e. plastically deformed) to form a counter-head. When the electrochemical cell provided with the two electrical collectors is inserted inside the cylindrical container, the electrical cathode collector (made of aluminium) is pressed against the counter-head of the rivet (previously coupled to the first wall of the cylindrical container) and then welded to the counter-head of the rivet in order to make a stable connection of great extension (the greater the contact area, the lower the electrical resistance at the contact area). Typically, the weld between the cathodic electrical collector and the counter-head of the rivet is made by using the central hole (with reduced dimensions) of the electrochemical cell to apply heat to the cathodic electrical collector and therefore melt the metal (aluminium) locally; in fact, generally it is not possible to apply heat in the zone between the cathodic electrical collector and the counter-head of the rivet passing from the first wall of the cylindrical container as, by doing so, the plastic gaskets that isolate the rivet from the cylindrical container would be damaged due to excess heating. SUMMARY OF THE INVENTION The Applicant has felt the need to provide a method to produce an energy storage battery that permits to operate at a high production speed (measured as batteries produced per unit time) while at the same time guaranteeing the achievement of a high-quality end product. The Applicant has first of all observed that the geometric proportions between a conventional electrochemical cell and the relative central hole make it uneasy to perform the weld through the central hole itself, especially at high production speeds. In particular, it is complex to apply heat for example to the bottom of this hole (i.e. at the cathodic electrical collector that is located at the end of the central hole of the electrochemical 25 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 cell); as a result, the welding operation requires high precision and is particularly slow, hence it requires a very long execution time and does not allow operating at a high production speed (measured as cylindrical batteries produced per unit time). The Applicant has also observed that any metal splashes generated during welding, (which by cooling down form small metal debris), remain trapped inside the hole of the jelly roll, or in any case inside the battery, being therefore able to "contaminate" the electrochemical cell, giving rise to small local short circuits, which over time can impair the performance thereof or even cause it to degrade prematurely. The Applicant has finally observed that the conventional weld through the hole of the jelly roll is difficult to inspect once it has been performed, making the subsequent quality controls difficult, or very slow, both on the line and on the finished product. The Applicant has therefore understood that an access, even temporary, from the outside of the container of the battery during welding allows to eliminate the presence of metal debris from the inside of the container, also facilitates the insertion of the welding head at high speed which does not find obstacles in its path, and it therefore allows operating at high speed while maintaining the quality of the end product. The Applicant has also noted that said access from the outside to the conductor(s) to be welded can also be guaranteed without necessarily exposing/making visible from the outside the conductor(s) to be welded, by using the so-called "transparent" weld. In other words, the conductor to be welded, although not visible from the outside, is advantageously accessible from the outside to receive the heat/energy necessary for its welding, which can therefore be delivered from the outside of the container. Thus, in accordance with the present invention there is provided a method to produce a battery for energy storage, comprising: - providing an electrochemical cell, which is at least partially complete and is provided with an electrical collector; - providing a container having a first wall; - placing, on an outer surface of the first wall, an outer body, which constitutes an electrical pole of the battery; - inserting the electrochemical cell into the container bringing the electrical collector close to the first wall; and 35 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 - providing the electrical collector with an access from the outside of the container in order to permit a weld between the electrical collector and the outer body; - welding the electrical collector and the outer body to one another at said access in order to establish an electrical connection. Preferably, the access comprises a first through hole made in the first wall. Preferably, the access comprises a second hole made in the outer body and arranged at least partially aligned with the first hole when the outer body is arranged on the outer surface of the first wall; and the weld is made at the second hole. Preferably, the weld is made from the outside of the container through the second hole and operating from the opposite side of the first wall relative to the electrochemical cell. Preferably, the weld is at least partially arranged inside the second hole. Preferably, the second hole is coaxial to the first hole when the outer body is arranged on the outer surface of the first wall. In embodiments, the second hole of the outer body is a through hole. In embodiments, the second hole of the outer body is blind and constitutes a recess into which a protrusion of the electrical collector is inserted. In embodiments, the electrical collector comprises a protrusion which is inserted into the first hole of the first wall and into the second hole of the outer body, and the weld is made between the outer body and the protrusion of the electrical collector. In embodiments, after having inserted the protrusion into the second hole, an outer surface of the protrusion is coplanar to an outer surface of the outer body. In embodiments, an outer surface of the protrusion, after having inserted the protrusion into the second hole, at first projects from an outer surface of the outer body; the second central hole of the outer body has an outer flaring; and the method further comprises the step of at least partially bucking the outer surface of the protrusion against the outer body so as to make the outer surface of the protrusion coplanar to the outer surface of the outer body. In embodiments, a rivet is provided which engages the first hole of the first wall and comprises a head which is arranged on the outside of the container and constitutes the outer body, and a counter-head, which is arranged inside the container. In embodiments, the rivet has, at first, only the head, whereas the counter-head is obtained 45 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 after having inserted the rivet through the first hole of the first wall by bucking the rivet against an inner surface of the first wall. Preferably, the outer body only consists of a connection element completely arranged on the outside of the container. Preferably, the protrusion of the electrical collector is surrounded, at the base, by a fixing element having the function of compressing an insulating gasket against an inner surface of the first wall. In embodiments, the electrical collector has no protrusion and the weld is made inside the second hole of the outer body. Preferably, the method comprises the further steps of: placing a first insulating gasket inside the access in order to line the access; placing a second insulating gasket between the outer body and an outer surface of the first wall; and placing a third insulating gasket between an inner surface of the first wall and the electrical collector. In embodiments, the weld is made from the outside of the container through the outer body, passing through the outer body from side to side, and operating from the opposite side of the electrochemical cell relative to the first wall. The appended claims describe embodiments of the present invention forming an integral part thereof. It is also clear that the product obtained by the method according to the present invention, in the embodiment that provides for a weld operated "in transparency", will show this type of weld among its characteristics. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described with reference to the enclosed drawings, showing some non-limiting embodiments thereof, wherein: • Figure 1 is a schematic side view of a cylindrical battery; • Figure 2 is a schematic side view on an enlarged scale of a first end of the cylindrical battery of Figure 1; • Figures 3-9 schematically illustrate a series of operations in order to make a positive pole of the cylindrical battery of Figure 2; 55 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 • Figures 10 and 11 schematically illustrate a variant of some operations in order to make the positive pole of the cylindrical battery of Figure 2; • Figure 12 is a schematic plan view of a first end of the cylindrical battery of Figure 1; • Figure 13 is a schematic side view on an enlarged scale of a first end of a variant of the cylindrical battery of Figure 1; • Figure 14 is a schematic side view on an enlarged scale of a first end of a further variant of the cylindrical battery of Figure 1; • Figures 15 and 16 schematically illustrate a series of operations in order to make a positive pole of the cylindrical battery of Figure 14; • Figures 17 and 18 schematically illustrate a variant of some operations in order to make the positive pole of the cylindrical battery of Figure 14; and • Figures 19-22 are schematic side views on an enlarged scale of a first end of other variants of the cylindrical battery of Figure 1. DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In Figure 1, the number 1 denotes as a whole an energy storage battery; the illustrated battery 1, by way of example only, is cylindrical in shape, without thereby limiting the scope of the invention. The battery 1 comprises an electrochemical cell 2 of cylindrical shape and of the ''jelly¬ roll'' or " Swiss-roll" type formed by several sheets superimposed and thus wound together so as to assume a cylindrical shape, and a cylindrical container 3 that encloses, on the inside, the electrochemical cell 2 and has a longitudinal axis 4 of symmetry which is arranged centrally. In particular, the cylindrical electrochemical cell 2 consists of a spiral winding of a set of four strips: a conductive strip of a metal-based material (typically aluminium) which constitutes the cathode, a separator strip made of a porous material (which is subsequently soaked with a liquid electrolyte), a conductive strip made of a metal-based material (typically copper) which constitutes the anode, and a separator strip made of a porous material (which is subsequently soaked with a liquid electrolyte). In other words, the four superimposed strips form a composite material (i.e., a "sandwich” of the four strips) that is spirally wound on itself so as to form the cylindrical electrochemical cell 2. The electrochemical cell 2 has centrally a through hole 5 65 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 (necessary for the realization of the spiral winding) that passes through it from side to side. The container 3 has a side wall 6 cylindrical in shape, a first end 7 which is closed since the beginning by a first wall 8 (that is, by a lower part) which is seamlessly connected to the side wall 6, and a second end 9 which is opposite to the first end 7, is at first open to permit the insertion of the electrochemical cell 2 into the container 3 and is subsequently closed and sealed. In particular, at the second end 9 of the container 3 a lid 10 is arranged (which in the case of the cylindrical battery is circular) which closes the second end 9 (i.e. it constitutes an upper base of the container 3). Before inserting the electrochemical cell 2 inside the container 3, at the two opposite ends of the electrochemical cell 2 two electrical collectors 11 and 12 are coupled (which in the specific case of the cylindrical battery are disc-shaped) at the cathode (in which an electrical aluminium collector 11 is used) and at the anode (in which an electrical copper collector 12 is used). Each terminal collector 11 or 12 constitutes an electrical collector (cathodic for the electrical collector 11 made of aluminium and anodic for the electrical collector 12 made of copper) which collects the electric currents that are generated inside the electrochemical cell 2 in order to permit to such electric currents to circulate on the outside of the electrochemical cell 2. Each terminal collector 11 or 12 is pressed against the corresponding end of the electrochemical cell 2 and is welded to connection lamellae of the conductive strips (made of aluminium and copper) which, wound together (with the interposition of insulating separators) constitute the electrochemical cell 2. The battery 1 comprises a negative electrical pole 13 which is arranged at the second end 9 and is made in the lid 10 and a positive electrical pole 14 which is arranged (with adequate electrical insulation as will be described below) at the first wall 8. In general, according to the present invention, the collector 11 is placed in communication with the outside of the container 3 by means of at least one access 15, 22, 26. As illustrated in Figure 2, the access comprises a hole 15. In particular, the first wall 8 of the container 3 has the through hole 15 (better illustrated in Figure 5) (in this case central) which is engaged by a rivet 16 (also called rivet, see Figure 7) made of aluminium having a head 17 that is arranged on the outside of the container 3 (i.e. on the outside of the first wall 8 of the container 3) and constitutes the positive electrical pole 14 of the battery 1 75 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 (i.e. the head 17 is a terminal that constitutes the positive electrical pole 14 of the battery 1). In particular, the rivet 16 is inserted through the hole 15 of the first wall 8 of the container 3 with the interposition of a series of plastic insulating gaskets 18, 19 and 20 that isolate the rivet 16 from the container 3 (in particular from the first wall 8 of the container 3) and then the headless end of the rivet 16 is bucked (i.e. plastically deformed) to form a counter-head 21. In other words, the rivet 16 engages the through hole 15 of the first wall 8 of the container 3 and comprises: a head 17 which is arranged on the outside of the first wall 8 of the container 3 and constitutes the positive electrical pole 14 of the battery 1; and a counter-head 21 which is arranged inside the first wall 8 of the container 3 and is therefore facing the cathodic electrical collector 11. The insulating gasket 18 has a cylindrical shape and internally lines the through hole 15 of the first wall 8 of the container 3, so as to isolate the rivet 16 from the walls of the hole 15. The insulating gasket 19 has a disc shape and is interposed between the head 17 of the rivet 16 and the first wall 8 of the container 3 in order to isolate the rivet 16 from the outer surface of the first wall 8. The insulating gasket 20 has a disc shape and is interposed between the counter-head 21 of the rivet 16 and the first wall 8 of the container 3 in order to isolate the rivet 16 from the inner surface of the first wall 8. In other words, the two insulating gaskets 19 and 20 are arranged on the opposite sides of the first wall 8 of the container 3. The rivet 16 has centrally the hole 22 which in the illustrated example is a through hole and is cylindrical in shape and which passes through the rivet 16 from side to side, and the electrical collector 11 has a protrusion 23 (which in the illustrated example is arranged centrally and is cylindrical in shape) which rises cantilevered from the electrical collector 11; the hole 22 of the rivet 16 is engaged by the protrusion 23 of the electrical collector 11. Furthermore, the hole 22 is arranged at least partially aligned (and preferably coaxial) with the hole 15 when the head 17 is arranged on the outer surface of the first wall 8. In general, the protrusion fits into the access 15, 22, 25. In this case, the access also comprises the hole 22. The hole 22 could also be a non-through hole and therefore constitute a recess (seat, 85 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 cavity, housing). That is, the rivet 16 could as an alternative to the through hole 22 comprise a non-through hole 22 which constitutes a recess (as illustrated in Figures 19 and 20). Preferably, the hole 22 of the rivet 16 houses the protrusion 23 of the electrical collector 11 with a reduced clearance, i.e. minimum clearance (a certain clearance is certainly necessary to allow the protrusion 23 of the electrical collector 11 to be fitted into the hole 22 of the rivet 16, but such clearance must be small in order to make it easier to subsequently realize the joining between the protrusion 23 and the hole 22). Between the rivet 16 and the protrusion 23 of the electrical collector 11 there is a preferably annular weld 24 (i.e. forming a closed ring as illustrated in Figure 12) which makes both a stable mechanical connection between the rivet 16 and the protrusion 23 of the electrical collector 11, and a low-resistance electrical connection between the rivet 16 and the protrusion 23 of the electrical collector 11 (for example the weld 24 could be made by means of a laser). The term weld generally refers to the result of the jointing / joining / fixing of elements together, regardless of the technique with which the operation takes place. For example, the jointing/joining/fixing can be by heat and/or mechanical pressure and/or vibrations; or it can result from a crimping or riveting of the parts to be joined. In embodiments, the weld can be a melting between elements (with or without filler material), for example a laser weld (to which reference will be made below by way of example only), an ultrasonic weld. With reference to Figures 3-9, the methods to make the positive electrical pole 14 of the battery 1 are described below. As illustrated in Figure 3, the electrical collector 11 provided with the protrusion 23 is connected to the electrochemical cell 2; the electrical collector 11 provided with the protrusion 23 is better illustrated in Figure 4. As illustrated in Figure 5, the through hole 15 (which in the figures is central) is made through the first wall 8 of the container 3. As illustrated in Figure 6, the first wall 8 of the container 3 is coupled with the insulating gaskets 18, 19 and 20: the insulating gasket 18 in the illustrated example has a cylindrical shape and internally lines the through hole 15 of the first wall 8 of the container 3, the 95 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 insulating gasket 19 in the illustrated example has a disc shape and is placed on the outer surface of the first wall 8, and the insulating gasket 20 in the illustrated example has a disc shape and is placed on the inner surface of the first wall 8. As illustrated in Figure 7, after having coupled the insulating gaskets 18, 19 and 20 to the first wall 8 of the container 3, through the hole 15 of the first wall 8 of the container 3 the rivet 16 is placed having the head 17 which is arranged on the outside of the container 3 (i.e. on the outside of the first wall 8 of the container 3), constitutes the positive electrical pole 14 of the battery 1, and compresses the insulating gasket 19 against the first wall 8 of the container 3; in this way, the head 17 is arranged on an outer surface of the first wall 8 of the container 3. At this point and as illustrated in Figure 8, the headless end of the rivet 16 is bucked (i.e. plastically deformed) in order to form the counter-head 21 which compresses the insulating gasket 20 against the first wall 8 of the container 3, in particular against an inner surface, opposite the aforementioned outer surface, of the first wall 8. Subsequently, as illustrated in Figure 9, the electrochemical cell 2 provided with the electrical collector 11, having (centrally) the protrusion 23 (which in the illustrated case is cylindrical) is inserted into the container 3; at the end of the insertion of the electrochemical cell 2, the protrusion 23 of the electrical collector 11 is inserted into the hole 22 of the rivet 16, engaging the hole 22 itself. Once the insertion of the electrochemical cell 2 into the container 3 is finished, that is, once the insertion of the protrusion 23 of the electrical collector 11 into the hole 22 of the rivet 16 is finished, the weld 24 is made which connects the rivet 16 to the protrusion 23 of the electrical collector 11 in order to establish both a good mechanical connection and a good electrical connection. It is important to note that the weld 24 (which in this case is annular) can be made from the outside of the container 3 and therefore without any kind of obstacle; consequently, the execution of the weld 24 can be completed quickly while still ensuring the achievement of a high overall quality. In essence, with the method according to the invention, the electrical collector 11 is (at least temporarily) placed in communication with the outside of the container (through the hole 15) and the weld 24 can thus be made from the outside of the container 3. In the embodiment illustrated in Figures 2-9, the outer surface of the protrusion 23 of the 105 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 electrical collector 11 is from the beginning coplanar to the outer surface of the head 17 of the rivet 16; in other words, the outer surface of the protrusion 23 is coplanar to the outer surface of the head 17 of the rivet 16 once it has been inserted into the hole 22 (once the protrusion 23 is inserted into the hole 22). In this embodiment, the hole 22 of the rivet 16 and the protrusion 23 have a shape (which in the illustrated case is cylindrical) substantially complementary to each other (i.e. without flaring) (a shape coupling is generated between the two). According to the alternative embodiment illustrated in Figures 10 and 11, the outer surface of the cylindrical protrusion 23 of the electrical collector 11 at first projects from the outer surface of the head 17 of the rivet 16, that is, once the protrusion 23 is inserted into the hole 22 it projects from the aforementioned outer surface; in this embodiment, the hole 22 of the rivet 16 has an outer flaring. After having inserted the cylindrical protrusion 23 of the electrical collector 11 into the hole 22 of the rivet 16, the outer part of the protrusion 23 is bucked against the head 17 of the rivet 16 by means of a plastic deformation so as to make the outer surface of the protrusion 23 of the electrical collector 11 coplanar to the outer surface of the head 17 of the rivet 16. According to a different embodiment illustrated in Figure 13, the electrical collector 11 has no protrusion 23 and the weld 24 is made between the counter-head 21 of the rivet 16 and the electrical collector 11 through the hole 22 of the rivet 16. According to a different embodiment illustrated in Figure 14, the rivet 16 is replaced by a connection element 25 (which in the illustrated case is a ring) which has (preferably centrally) a through hole 26, which in the illustrated case has a cylindrical shape, which passes through the connection element 25 from side to side; the hole 26 of the connection element 25 is engaged by the protrusion 23 of the electrical collector 11. In particular, the hole 26 is arranged at least partially aligned (and preferably coaxial) with the hole 15 when the connection element 25 is arranged on the outer surface of the first wall 8. In this case, the access comprises the hole 26. Between the connection element 25 and the protrusion 23 of the electrical collector 11 there is a weld 24 which makes both a stable mechanical connection between the connection element 25 and the protrusion 23 of the electrical collector 11 and a lowresistance electrical connection between the connection element 25 and the protrusion 23 115 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 of the electrical collector 11. In this embodiment, the positive electrical pole 14 of the battery 1 consists of the connection element 25 that replaces the head 17 of the rivet 16. In the embodiment illustrated in Figure 14, the protrusion 23 of the electrical collector 11 is surrounded internally by a fixing element 27 (which in the illustrated case is a ring) having the function of compressing (and therefore keeping in place) the insulating gasket 20 against the inner surface of the first wall 8 of the container 3. Figures 15 and 16 illustrate some realization steps of the embodiment illustrated in Figure 14 that allow us to better see the conformation of the connection element 25 and of the protrusion 23 of the electrical collector 11. In the embodiment illustrated in Figures 14-16, the outer surface of the protrusion 23 of the electrical collector 11 is from the beginning coplanar to the outer surface of the connection element 25, that is it is coplanar to it once it has been inserted into the hole 26. In this embodiment, the hole 26 of the connection element 25 has a shape (which in this case is cylindrical) substantially complementary to the protrusion 23 (i.e., with no flaring) (a shape coupling is generated). According to the alternative embodiment illustrated in Figures 17 and 28, the outer surface of the protrusion 23 of the electrical collector 11 at first projects from the outer surface of the connection element 25, i.e. it projects therefrom once the protrusion 23 is inserted into the hole 26. In this embodiment, the hole 26 of the connection element 25 has outwardly a flaring. After having inserted the protrusion 23 of the electrical collector 11 into the hole 26 of the connection element 25, the outer part of the protrusion 23 is bucked against the connection element 25 by means of a plastic deformation so as to make the outer surface of the protrusion 23 of the electrical collector 11 coplanar to the outer surface of the connection element 25. In the embodiments illustrated in Figures 1-18, the hole 22 of the rivet 16 or the hole 26 of the connection element 25 are through holes, i.e. the hole 22 passes through the rivet 16 from side to side and the hole 26 passes through the connection element 25 from side to side, and therefore the protrusion 23 of the electrical collector 11 is directly visible outside the container 3 (i.e. outside the rivet 16 or the connection element 25). According to a different embodiment illustrated in Figure 22 the hole 26 of the outer connection element 25 is absent. In this circumstance, the weld 24 is made from the outside of the container 3 in 125 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 "transparency", that is, through the outer connection body 25, and operating from the opposite side of the electrochemical cell 2 relative to the wall 8. This weld 24 is made from the outside in "transparency" since the heat necessary to melt the metal of the upper part of the protrusion 23 of the electrical collector 11 is not supplied directly to the protrusion 23 of the electrical collector 11 but passes through the connection element 25 (which is sufficiently thin) to reach the upper part of the protrusion 23 of the electrical collector 11. The thickness of the connection element 25 is preferably comprised between 0.2 mm and 0.6 mm. The weld 24 is preferably operated with a laser. According to a different embodiment illustrated in Figures 19-21, the hole 22 of the rivet 16 and the hole 26 of the connection element 25 are blind as they have a (preferably thin) upper wall that closes the holes 22 and 26 and hides the protrusion 23 of the electrical collector 11 from view; in this case, the protrusion 23 of the electrical collector 11 is not directly visible outside the container 3 as it is completely hidden by the rivet 16 or by the connection element 25. In other words, as illustrated in Figures 19 and 20, the hole 22 of the rivet 16 is blind (not a through hole) and therefore defines a recess (seat, cavity, housing) inside which the protrusion 23 of the electrical collector 11 is arranged; therefore the weld 24 must pass through a portion of the head 17 of the rivet 16 from side to side to reach the protrusion 23 of the electrical collector 11 (as mentioned above, the weld 24 is made from the outside). In the embodiment illustrated in Figure 19, the head 17 of the rivet 16 is thinner at the protrusion 23 of the electrical collector 11 (i.e. at the weld 24 and of the hole 22), while in the embodiment illustrated in Figure 20 the head 17 of the rivet 16 has a uniform thickness everywhere. Preferably, in both cases the thickness is comprised between 0.2 mm and 0.6 mm. Similarly, as illustrated in Figure 21, the hole 26 of the connection element 25 is blind (not a through hole) and therefore defines a recess (seat, cavity, housing) inside which the protrusion 23 of the electrical collector 11 is arranged; therefore the weld 24 must pass through a portion of the connection element 25 from side to side to reach the protrusion 135 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 23 of the electrical collector 11 (as mentioned above, the weld 24 is made from the outside). In the embodiment illustrated in Figure 21, the head 17 of the rivet 16 is thinner at the protrusion 23 of the electrical collector 11 (i.e. at the weld 24 and the hole 26). As highlighted above, in the embodiments illustrated in Figures 19-22, the weld 24 is made from the outside in "transparency" since the heat necessary to melt the metal of the upper part of the protrusion 23 of the electrical collector 11 is not supplied directly to the protrusion 23 of the electrical collector 11, but passes through the rivet 16 or through the connection element 25, passing through them from side to side, to reach the upper part of the protrusion 23 of the electrical collector 11. In the embodiments illustrated in the accompanying figures, the battery 1 has a cylindrical shape and therefore consequently at least a part of the components of the battery 1 (e.g., the electrochemical cell 2 and the container 3) have a cylindrical shape (or in any case a shape with cylindrical symmetry); according to other embodiments not illustrated, the battery 1 has a shape other than the cylindrical shape (e.g., a parallelepiped shape) and therefore at least a part of the components of the battery 1 (e.g., the electrochemical cell 2 and the container 3) have a shape other than the cylindrical shape (e.g., a parallelepiped shape). That is, the electrochemical cell 2 and the container 3 could have a prismatic shape with a circular base (and therefore be cylindrical-shaped) or they could have a prismatic shape with a rectangular or square base (and therefore be parallelepipeds). The head 17 which is arranged on the outside of the container 3 (i.e. on the outside of the first wall 8 of the container 3) and constitutes the positive electrical pole 14 of the battery 1 may have a cylindrical shape (as illustrated in the accompanying figures) or also a shape other than the cylindrical shape (for example a parallelepiped shape). In a further embodiment not illustrated, access to the electrical collector 11 to be welded takes place exclusively through the container 3 without affecting the outer body 17, 25. In this embodiment, the first wall 8 of the container 3 comprises the hole 15 for inserting the rivet 16 and a further through hole through which a protrusion 23 of the electrical collector 11 is inserted; the weld 24 is made (from the outside) between the head 17 and the protrusion 23 of the electrical collector 11. The energy storage battery in accordance with the previous embodiment therefore comprises: an electrochemical cell 2; an electrical collector 11 which is coupled to one 145 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 end of the electrochemical cell 2; a container 3 which has a first wall 8 having a first through hole 15 and houses, on the inside, the electrochemical cell 2 so that the electrical collector 11 is arranged close to the first wall 8; a rivet 16 inserted into the first hole 15; and a further through hole on the first wall 8 of the container 3 through which a protrusion 23 of the electrical collector 11 is inserted, wherein a weld 24 is made between the head 17 of the rivet 16 and the protrusion 23 of the electrical collector 11. The embodiments described herein may be combined with each other without departing from the scope of protection of the present invention. The production method and the battery 1 described above have numerous advantages. Firstly, the production method and the battery 1 described above make it possible to operate at a high production speed (i.e. with a high number of cylindrical containers 3 produced in the unit of time) thanks to the fact that the annular weld 24 is made on the outside of the container 3 and therefore without any spatial constraint on the dimension and on the movement of the welding tools. This is possible by placing in (at least temporary) communication the electrical collector 11 with the outside of the container 3 (through the hole 15 and/or the hole 22/26) in order to be able to perform the weld 24 from the outside of the container 3. Furthermore, the production method and the battery 1 described above make it possible to guarantee the achievement of a high quality of the end product (i.e. a reduced defectiveness); this result is obtained thanks to the fact that the weld 24 is not made inside the (i.e. from the inside of) the container 3, but is made outside the (i.e. from the outside of) the container 3; in this way, any metal debris that accidentally form while making the weld 24 do not enter inside the container 3 but remain on the outside of the container 3 and therefore cannot pollute the cylindrical electrochemical cell 2. In other words, while making the annular weld 24, splashes of molten metal can originate which, by cooling down, form small metal debris; however such small debris cannot enter the container 3 as the weld 24 is made outside the container 3. The absence of any metal debris generated by the weld 24 inside the container 3 permits to substantially reduce the defectiveness of the electrochemical cell 2, since these small metal debris, if any, could give rise to small local short circuits that over time can cause a premature degradation of the electrochemical cell 2. 155 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605 Furthermore, the thickness of the electrical collector 11 can be limited (i.e. the thickness of the electrical collector 11 may not be increased) to the advantage of the reduction of the height of the battery 1 as the electrical collector 11 does not have to withstand the breakthrough that may occur while making the weld 24, because the weld 24 (in the embodiment illustrated in Figures 2-11) does not directly affect the electrical collector 11 but affects the protrusion 23 of the electrical collector 11. The fact that the rivet 16 has the through hole 22 (or alternatively that the connection element 25 has the through hole 26) simplifies (speeds up) the insertion of the electrochemical cell 2 into the container 3, in that as the electrochemical cell 2 enters the container 3 the air present at the bottom of the container 3 that is compressed by the advancement of the electrochemical cell 2 can more effectively be vented through the through hole 22 of the rivet 16 rather than be vented through the hole 5 of the electrochemical cell 2 (as would necessarily be the case in the absence of the through hole 22 of the rivet 16). Finally, the production method and the battery 1 described above are simple and inexpensive to implement as they do not require complex mechanical machining or the use of particular (non-standard) materials. LIST OF REFERENCE NUMBERS OF THE FIGURES 1 battery 2 electrochemical cell 3 container 4 longitudinal axis 5 through hole 6 side wall 7 first end 8 first wall 9 second end 10 lid 11 electrical collector 12 electrical collector 13 negative electrical pole 16WO 2023/148550 PCT/IB2022/062605 14 positive electrical pole 15 hole 16 rivet 17 head 5 18 insulating gasket 19 insulating gasket 20 insulating gasket 21 counter-head 22 hole 10 23 protrusion 24 weld 25 connection element 26 hole 27 fixing element 17

Claims

CLAIMS 1. A method to produce an energy storage battery (1) comprising the steps of: providing an electrochemical cell (2), which is at least partially complete and is provided with an electrical collector (11); providing a container (3) having a first wall (8); placing, on an outer surface of the first wall (8), an outer body (17; 25), which constitutes an electrical pole (14) of the battery (1); inserting the electrochemical cell (2) into the container (3) bringing the electrical collector (11) close to the first wall (8); and providing the electrical collector (11) with an access (15; 22; 26) from the outside of the container (3) in order to permit a weld (24) between the electrical collector (11) and the outer body (17; 25); welding the electrical collector (11) and the outer body (17; 25) to one another at said access (15; 22; 26) in order to establish an electrical connection.
2. The production method according to claim 1, wherein said access (15; 22; 26) comprises a first through hole (15) made in the first wall (8).
3. The production method according to claim 2, wherein the access (15; 22; 26) comprises a second hole (22; 26), which is made in the outer body (17; 25) and is at least partially aligned with the first hole (15), when the outer body (17; 25) is arranged on the outer surface of the first wall (8); and the weld (24) is made at the second hole (22; 26).
4. The production method according to claim 3, wherein the weld (24) is made from the outside of the container (3) through the second hole (22; 26) and operating from the opposite side of the electrochemical cell (2) relative to the first wall (8).
5. The production method according to claim 3 or 4, wherein the weld (24) is at least partially arranged inside the second hole (22; 26).
6. The production method according to claim 3, 4 or 5, wherein the second hole (22; 26) is coaxial to the first hole (15), when the outer body (17; 25) is arranged on the outer surface of the first wall (8).
7. The production method according to one of the claims from 3 to 6, wherein the second hole (22; 26) of the outer body (17; 25) is a through hole. 185 10 15 20 25 30 WO 2023/148550 PCT/IB2022/062605
8. The production method according to one of the claims from 3 to 6, wherein the second hole (22; 26) of the outer body (17; 25) is blind and forms a recess into which a protrusion (23) of the electrical collector (11) is inserted.
9. The production method according to one of the claims from 3 to 8, wherein: the electrical collector (11) comprises a protrusion (23), which is inserted into the first hole (15) of the first wall (8) and into the second hole (22; 26) of the outer body (17; 25); and the weld (24) is made between the outer body (17; 25) and the protrusion (23) of the electrical collector (11).
10. The production method according to claim 9, wherein, after having inserted the protrusion (23) into the second hole (22; 26), an outer surface of the protrusion (23) is coplanar to an outer surface of the outer body (17; 25).
11. The production method according to claim 9, wherein: an outer surface of the protrusion (23), after having inserted the protrusion (23) into the second hole (22; 26), at first projects from an outer surface of the outer body (17; 25); the second central hole (22) of the outer body (17; 25) has outwardly a flaring; and the method further comprises the step of at least partially bucking the outer surface of the protrusion (23) against the outer body (17; 25) so as to make the outer surface of the protrusion (23) coplanar to the outer surface of the outer body (17; 25).
12. The production method according to claim 9, 10 or 11, wherein a rivet (16) is provided, which engages the first hole (15) of the first wall (8) and comprises a head (17), which is arranged on the outside of the container (3) and constitutes the outer body (17; 25), and a counter-head (21), which is arranged inside the container (3).
13. The production method according to claim 11, wherein the rivet (16) has, at first, only the head (17), whereas the counter-head (21) is obtained after having inserted the rivet (16) through the first hole (15) of the first wall (8) by bucking the rivet (16) against an inner surface of the first wall (8).
14. The production method according to claim 9, 10 or 11, wherein the outer body (17; 25) consists of only a connection element (25) completely arranged on the outside of the container (3).
15. The production method according to claim 14, wherein the protrusion (23) of the 195 10 15 20 25 WO 2023/148550 PCT/IB2022/062605 electrical collector (11) is surrounded, at the base, by a fixing element (27) having the function of compressing an insulating gasket (20) against an inner surface of the first wall (8).
16. The production method according to one of the claims from 3 to 7, wherein the electrical collector (11) has no protrusion and the weld (24) is made inside the second hole (22; 26) of the outer body (17; 25).
17. The production method according to claim 1, wherein: the electrical collector (11) comprises a protrusion (23), which is inserted into the first hole (15) of the first wall (8); and the weld (24) is made between the outer body (17; 25) and the protrusion (23) of the electrical collector (11).
18. The production method according to one of the claims from 1 to 17 and comprising the further steps of: placing a first insulating gasket (18) inside the access (15; 22; 26) in order to line the access (15); placing a second insulating gasket (19) between the outer body (17; 25) and an outer surface of the first wall (8); and placing a third insulating gasket (20) between an inner surface of the first wall (8) and the electrical collector (11).
19. The production method according to claim 1 or 2, wherein the weld (24) is made from the outside of the container (3) through the outer body (17; 25), passing through the outer body (17; 25) from side to side, and operating from the opposite side of the electrochemical cell (2) relative to the first wall (8). 20