Method for manufacturing an energy storage device

Abstract

A method for manufacturing an energy storage device (10) is proposed. The method comprises the following steps: providing a housing (1) with an electrode winding (2), hereinafter referred to as a "jellyroll", filling the housing (1) with a first quantity of electrolyte (3), applying a vacuum to the filled housing (1), and subsequently filling the housing (1) with a second quantity of electrolyte (3).

Description

[0001] The present invention relates to a method for producing an energy storage device, in particular a round electric cell. In particular, the present invention relates to a space-efficient and rapid production of an energy storage device.

[0002] In the current state of the art, round electrical cells are used for a wide variety of electrical devices and drives when it comes to the mobile provision of electrical energy. In automotive technology, too, fully electric or hybrid-powered vehicles are increasingly being equipped with round cells or cylindrical storage cells. Production comprises a large number of steps, which must sometimes be carried out at considerable intervals from one another, as time-consuming processes within the housing must first subside before the next step can be carried out. One of these steps is the absorption of the filled electrolyte by the jellyroll (electrode winding). Filling a typical cylindrical round cell can take 30 to 40 minutes. During this time, the cell must be supplied with electrolyte via a nozzle. During this time, the nozzle cannot be used to fill additional cells.

[0003] It is an object of the present invention to accelerate the production of a cylindrical electric cell. In particular, it is an object of the present invention to make the production line more compact.

[0004] The above-mentioned object is achieved according to the invention by a method for producing an energy storage device having the features according to claim 1. The subclaims show preferred developments of the invention.

[0005] The energy storage device can be a large cylindrical cell (model 46950). In a first step, a housing for the energy storage device is provided with an electrode coil and prepared. In a further step, the free space within the housing is filled with an initial amount of electrolyte. This volume is also referred to as the “dead volume” and requires little or no capillary action. In other words, pores easily accessible through the electrolyte and any other free space in the housing are filled. This process can take, for example, 1 to 5 minutes, preferably 2 to 4 minutes. The filled housing is then subjected to negative pressure, causing the gas it contains, particularly air, to escape from the housing and be replaced by electrolyte. The electrolyte located outside the jellyroll (i.e., in the dead volume) is sucked into the jellyroll.Finally, the filled housing is filled with a second amount of electrolyte. This allows the dead volume to be filled with electrolyte again easily and quickly, as no capillary action is required. The process can take anywhere from 5 seconds to 20 seconds, preferably between 8 seconds and 15 seconds. This drastically reduces the overall production time for an electrical cell or energy storage device. In particular, the time the energy storage device is attached to the nozzle is significantly shorter, meaning fewer nozzles are required to produce a fixed number of energy storage devices per unit of time.

[0006] Preferably, the first amount of electrolyte can be greater than the second amount of electrolyte. In particular, the first amount of electrolyte can be twice, four times, or even five times the second amount of electrolyte. This amount cannot always be accommodated in the dead volume, so that, particularly during the initial filling of the housing with electrolyte, a collar, a nozzle, or a hose line temporarily attached to the housing during production is also (proportionately) filled with the first amount of electrolyte. The first amount of electrolyte is thus distributed over the dead volume and, in particular, a volume arranged externally on the housing.

[0007] The filled housing can be subjected to negative pressure via the same nozzle. In particular, the housing can be filled via the same nozzle that is subsequently used for vacuuming or creating the negative pressure in the housing. Applying negative pressure to the filled housing can last between one second, in particular ten seconds, and one hour. In this case, negative pressure can be applied to each cell at a time, or several cells / housings / energy storage devices can be arranged in a common negative pressure chamber to accelerate the moistening of the jellyroll.

[0008] In any case, during the initial filling of the housing, an electrolyte overflow must be created on the housing, from which the electrolyte can penetrate into the jellyroll during the application of negative pressure. Electrolyte from the overflow flows into the dead volume within the housing and from there into the jellyroll, and / or is fed directly into the jellyroll from the overflow.

[0009] To attach the nozzle to the housing, a seal can be arranged on the nozzle and / or on an opening in the housing, providing a fluid-tight seal against the housing. In the case of a cylindrical cell, an opening in its lid and / or base can be enclosed by an O-ring seal once the nozzle has been attached to the housing.

[0010] Applying negative pressure to the filled housing may include a step in which the entire housing is temporarily placed in a vacuum chamber so that the housing wall is not exposed to any pressure difference. For this purpose, the energy storage device can be placed in an upright position on a flat surface, which is then sealed against a vacuum bell / suction bell. This also avoids the need to press a seal against the (potentially sensitive) housing for the purpose of applying negative pressure.

[0011] Particularly during the filling of the housing with an electrolyte, excess pressure can arise within the housing. To support the housing, the exterior of the housing can be enclosed and / or supported by fluid overpressure. For example, the line or nozzle for filling the housing can itself be located in an overpressure chamber through which a (preferably gaseous) fluid flows under pressure around the housing, thus (at least partially) compensating for the electrolyte overpressure prevailing in the housing. In this way, damage to the housing during the method according to the invention can be prevented.

[0012] After the second filling of the housing with the second amount of electrolyte, the steps for manufacturing an energy storage device that are generally known in the prior art can follow. For example, an electrical charge (pre-charge), temperature-induced aging, further degassing processes, and forming can be carried out. These are generally known and are therefore understood as components of the manufacturing process that optionally supplement the steps according to the invention in a known manner. Finally, the housing is closed, for example, by inserting a lid into the opening. Subsequently, finishing, coating, or welding processes can be carried out to seal and finish the manufactured electrochemical energy storage device.

[0013] Further details, features, and advantages of the invention will become apparent from the following description and the figures. They show: Fig. 1 to Fig. 6 steps of an embodiment of a method according to the invention for producing an energy storage device; Fig. 7 an alternative to Fig. 3 shown application of negative pressure; Fig. 8 an alternative execution of the steps described in Fig. 2 or in Fig. 4 are shown; and Fig. 9 a flowchart illustrating steps of an embodiment of a method according to the invention for producing an energy storage device.

[0014] Fig. Figure 1 shows the starting point of the method according to the invention, in which an electrode coil, hereinafter referred to as "jellyroll 2," is arranged in a housing 1 of an energy storage device. At the bottom of the image, the positive pole 8 is inserted into the housing base. At the top, the lid 6 is provided with an opening 12. The opening 12 is intended to be used for filling and applying negative pressure to fill the dead volume 7 between the housing 1 and the jellyroll 2.

[0015] Fig. 2 shows the initial filling of the housing 1 with electrolyte 3. Via a hose 9 and a nozzle 4, which is pressed onto the cover 6 via an O-ring seal in the form of a seal 5, electrolyte subjected to excess pressure can be introduced into the dead volume 7 ( Fig. 1) and penetrate directly into Jellyroll 2.

[0016] Fig. Figure 3 shows the step following the initial filling of applying negative pressure via a vacuum hose 11, which is attached to the nozzle 4. The application of negative pressure leads to degassing of the housing 1 via the opening 12, whereby the level of the electrolyte 3 lowers and the electrolyte 3 penetrates the jellyroll 2 (shaded area 2, 3).

[0017] Fig. 4 shows the step of filling the housing with a second amount of electrolyte 3, for which the hose 9 has again been attached to the nozzle 4 in order to finally fill the dead volume 7 within the housing 6 with electrolyte 3.

[0018] Fig. 5 shows the result of the Fig. 4, after which the housing 6 is completely filled with the jellyroll 2 and electrolyte 3. There is no longer any excess electrolyte in the nozzle 4.

[0019] Fig. Figure 6 shows a final step in the manufacture of an energy storage device according to the invention, in which a plug is inserted into the opening 12 of the housing 1 as a closure 18 in the cover 6 (arrow P). Not shown are further optional steps or steps generally known in the prior art, which can be inserted between and / or followed by the steps described above.

[0020] Fig. Figure 7 shows an alternative procedure for applying negative pressure to the initially filled housing 1. For this purpose, a nozzle 4 is used which is so large that it could also be understood as a suction cup or vacuum chamber. Via a seal 5, the nozzle 4 terminates in a flat surface 14 in which a recess 13 is provided for the positive terminal 8 in order to ensure a secure stand of the housing 1. The procedure shown prevents mechanical and in particular fluid-mechanical stress on the housing 1. The volume to be vacuumed within the vacuum chamber 15 is, however, larger than in the Fig. 3. However, a less precise positioning of the nozzle 4 can also be used.

[0021] Fig. Figure 8 shows an alternative procedure for filling the housing 1 with electrolyte 3. This can be the initial or further filling of the housing 1. An inner nozzle 4 is pressurized with electrolyte 3 via a hose 9. This can generate excess pressure, which could fundamentally deform or even damage the housing 1. To prevent this, a gas 17 is fed into the outer nozzle 4 via another hose 16, which (partially) compensates for any excess pressure within the housing 1. In this way, the housing 1 can be prevented from deforming or becoming damaged.

[0022] Fig.9 shows a flowchart illustrating steps of an embodiment of a method according to the invention for producing an energy storage device. In step 100, a housing with an electrode coil therein is provided. In this process, after the electrode coil has been inserted into a cell can, a lid (preferably with an opening for the subsequent steps) can be closed. In step 200, the housing is filled with a first amount of electrolyte at a first point in time. This process can last, in particular, 1 minute to 5 minutes. Subsequently, in step 300, the initially filled housing is subjected to a negative pressure. In this case, electrolyte standing above the housing can flow into the housing and penetrate the jellyroll. In step 400, a second step according to the invention for filling the housing with a second amount of electrolyte is subsequently carried out. This process can last, in particular, 5 seconds to 25 seconds, preferably 8 seconds to 15 seconds.Since only the dead volume within the housing, but not the jellyroll, is now capable of absorbing electrolyte, this process is significantly shorter than the initial filling with electrolyte. Finally, the processes known in the prior art for completing the electrochemical energy storage device are carried out and are summarized in step 500, namely the closing of the housing 1 with a closure element.

[0023] The result is a particularly time-saving and throughput-increasing process for producing an electrochemical energy storage device. List of reference symbols: 1 housing 2 electrode wraps (jellyroll) 3 Electrolyte 4 nozzles 5 Seal 6 lids 7 Dead volume 8 Positive pole 9 Hose 10 energy storage 11 Vacuum hose 12 Opening 13 Recess 14 Area 15 Vacuum chamber 16 hose 17 Fluid 18 Closure 100 to 500 process steps

Claims

[1] Method for producing an energy storage device (10) comprising the steps: - Providing (100) a housing (1) with an electrode coil (2), hereinafter referred to as “jelly roll”, - filling (200) the housing (1) with a first quantity of electrolyte (3), - Applying (300) a negative pressure to the filled housing (1), and then - Filling (400) the housing (1) with a second quantity of electrolyte (3). [2] Method according to claim 1, wherein the first amount of electrolyte (3) is greater than the second amount of electrolyte (3), in particular at least four times the second amount of electrolyte (3). [3] Method according to one of the preceding claims, wherein - the exposure of the filled housing (1) to a negative pressure lasts between one second and one hour. [4] Method according to one of the preceding claims, wherein - filling the housing (10) with the first quantity of electrolyte (3) comprises filling a nozzle (4) which is temporarily attached to the housing (1) during manufacture. [5] Method according to claim 4, wherein the nozzle (4) is also used to apply the negative pressure to the filled housing (1). [6] Method according to one of the preceding claims, wherein a seal (5) is temporarily attached to a lid (6) in order to apply a negative pressure to the filled housing (1). [7] Method according to one of the preceding claims, wherein in order to apply a negative pressure to the filled housing (1), the entire housing (1) is temporarily arranged in a negative pressure chamber (15). [8] Method according to one of the preceding claims, wherein an outer side of the housing (1) is subjected to an overpressure in order to fill the housing (1) with electrolyte (3). [9] Method according to one of the preceding claims, further comprising - Inserting (500) a closure (18) into the housing (1). [10] Method according to one of the preceding claims, wherein - filling the housing (10) with the first amount of electrolyte (3) takes between one second and ten minutes, and / or - filling the housing (10) with the second quantity of electrolyte (3) takes between 3 s and 20 s, in particular between 5 s and 10 s.

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