Device, method and system for filling semi-finished batteries

Abstract

This disclosure concerns the field of electrolytic cell battery production, in particular but not exclusively lithium-ion batteries. In particular, the disclosure concerns the step of filling the containers defining the cells with electrolyte, these containers being, for example, generically cylindrical or prismatic in shape but also being able to take on different shapes and configurations. The disclosure thus extends to the method of filling these semi-finished batteries, to a device configured for this operation, and to a system specifically structured to carry out the method.

Description

[0001] TITLE

[0002] DEVICE, METHOD AND SYSTEM FOR FILLING SEMI-FINISHED BATTERIES

[0003] DESCRIPTION

[0004] Technical sector of the disclosure

[0005] This disclosure concerns the field of electrolytic cell battery production, in particular but not exclusively lithium-ion batteries. In particular, the disclosure concerns the step of filling the containers defining the cells with electrolyte, these containers being, for example, generically cylindrical or prismatic in shape but also being able to take on different shapes and configurations. The disclosure thus extends to the method of filling these semi-finished batteries, to a device configured for this operation, and to a system specifically structured to carry out the method.

[0006] Background of the disclosure

[0007] The battery cells referred to comprise a container, for example and typically a rigid cylindrical container, inside of which is housed a stack or a roll of ribbon-like electrode elements, alternating between anode and cathode formations, with separating layers of porous material in between, and with associated conductive parts.

[0008] Filling the cell / container with the liquid electrolyte represents a considerable challenge for battery manufacturers. In fact, the electrolyte must fill all the available space, and in particular effectively penetrate all the channels of the electrode body, impregnating the porous material separating the anodic and cathodic formations. The electrolyte is fed in through an adduction bore made in the cell container, a bore which is plugged and sealed permanently after filling. This step is also called the “soaking” step.

[0009] If it is to be carried out correctly and qualitatively satisfactorily, including verifying that the filling is not affected by the presence of air bubbles, this operation is necessarily very time-consuming and therefore costly. In this regard, it is well known that techniques are used to promote the penetration of the electrolyte, involving the use of means to create a vacuum, as well as an action in multiple successive steps, alternating filling steps with pauses for soaking or wetting the porous separation material by the electrolyte.

[0010] In the particular case of so-called “tabless” batteries, well known those skilled in the art, the flattening of the electrode roll heads further hinders the penetration of liquid between the wound coils, hence the need for even longer filling and wetting times.

[0011] As mentioned, the prior art contemplates a few attempts to solve the problem, all of which, however, entail significant structural complications, namely involving the use of specific devices for transferring the electrolyte into the cell, e.g. by means of a piston mechanism (see, for example, the disclosure in patent publication WO2024079268). In addition to the inherent complication brought about by such auxiliary devices and the secondary mechanical equipment to operate them, in these systems it is provided to entrust the step of transferring the electrolyte from the auxiliary device to the cell to environments outside the one in which the (main) machine supplying the electrolyte to the auxiliary device operates, so as not to occupy too much and for too long the protected environment in which the aforesaid machine must necessarily operate in order to avoid contamination of the electrolyte. This flow is precisely the source of a further logistical / structural complication, as airtight chambers are required for the exit and subsequent re-entry of the devices and cells into the protected environment, which results in an intrinsic consumption of treated air, and may also require further dehumidification / decontamination of the exposed product surfaces upon re-entry. After all, auxiliary transfer devices, replicated in large numbers, require a high maintenance effort or periodic replacement cost.

[0012] Known systems using vacuum creation techniques to facilitate filling include the disclosure of patent document EP4358286. In such a solution, a complex double chamber system separated by a valve coupled to the cell is provided to make the air suction independent of the actual filling. In addition to the added mechanical complexity, there is the problem of a remaining dead volume of air that is not emptied into the first liquid chamber. A further problem is the pressure surge and resulting cavitation that can occur when the two chambers are connected.

[0013] Summary of the disclosure

[0014] Starting from this situation, the present applicant has identified a novel system for filling semi-finished batteries such as the cells described above, which is able to overcome the drawbacks and solve the problems just outlined.

[0015] A method and system for filling battery cells that achieves the purposes listed above has the essential characteristics set out in the appended independent claims. Other significant characteristics are the subject of the dependent claims.

[0016] Conceptually, the disclosure involves filling an auxiliary device in the form of a container, typically but not necessarily a bottle or funnel, with electrolyte in an amount commensurate with what is necessary for the effective filling of a standard cell, and in any case defining an internal compartment to accommodate the electrolyte and having an outlet at least intended for its exit to the battery cell. The device is mechanically passive, i.e. it has no elements capable of mechanically promoting a thrust on the electrolyte mass.

[0017] The aforementioned port of such an auxiliary receptacle has a reversible and tight coupling configuration with the inlet of the cell to be filled, so as to achieve hydraulic communication between the port of the auxiliary receptacle and the opening of the cell, so that the fluid can flow from the service receptacle to the cell, by gravity and capillarity alone and in the absence of mechanical intervention and action from outside. At least one air vent system can be provided in the auxiliary receptacle to allow filling by the liquid mass.

[0018] According to an embodiment of the present disclosure, the auxiliary receptacle is first placed with the port upwards, then the assembly is coaxially made with the battery cell, and finally the assembly is turned upside down to allow the electrolyte to drain, for the time required for complete wetting, into a storage region. According to other aspects of the present disclosure, the auxiliary receptacle, whether open or closed, is directly assembled on the cell in the overturned position, i.e. with the cell resting or supported on its bottom and the receptacle arranged with its port downwards.

[0019] Once the transfer of electrolyte has been carried out, the now-empty service receptacle can be detached from the cell and reused, while the cell can be plugged and definitively sealed, in order to move on to the subsequent electrical formation steps. Auxiliary devices will be provided in a large number, which can be approximately in the order of magnitude of the ratio of total process time (cell filling) divided by the cycle time of the filling machine of the individual auxiliary receptacle. This ensures that the operation has adequate productivity.

[0020] According to an aspect of the present disclosure, the bottle-shaped auxiliary receptacle can be provided with an outward check valve in its upper area, through which the air contained both in the battery cell and in the dead volume above the free fluid layer in the bottle can be extracted in a single operation.

[0021] However, according to an alternative embodiment, to obviate the technical difficulty and cost in creating the vacuum within the assembly of cell and auxiliary receptacle, it is also possible to simply equip the port of the latter with at least one vent tube for the extraction of any residual air from the cell towards the bottom of the overturned receptacle, and more preferably a double tube, one for the descent of the electrolyte and the other for venting / extraction. Both of these tubes have a significant longitudinal extension to prevent spillage in the first case and air bubbles in the second.

[0022] Thanks to this artifice, and in any case to the long time made available for fluid transfer, the preliminary air extraction may be partial or even absent.

[0023] To allow time for wetting, the hermetically sealed auxiliary cell assemblies are stored in a high-density FIFO (“first in first out”) type of storage, which can be, in the preferred version, a stack of trays each containing a matrix of products close to or in contact with each other.

[0024] It is easy to understand how the overall footprint of such storage in a protected environment “dry room’’) can in itself be smaller than that of sealed-chamber inlet and outlet systems alone (which, moreover, would entail an intrinsic consumption of expensive deumidified air, and the contamination of the external surface of both the cell and the service receptacle).

[0025] A further advantage of auxiliary or passive service receptacles according to the disclosure over more complex devices is the possibility of calibrating their weight in advance so that it is the same for all within very narrow tolerances and remains invariable with respect to wear and tear: this allows accurate weighing in a single step (without having to resort to the artifice of double weighing) of the liquid introduced at filling.

[0026] Short description of the drawings

[0027] The characteristics and advantages of the device, method and system for filling semi-finished batteries according to the present disclosure will become clearer from the following description of its embodiment examples, made by way of non-limiting reference to the accompanying drawings in which:

[0028] - Figures 1 a to 1 m represent a sequence of successive steps in a method for filling a battery cell with an auxiliary receptacle according to a first aspect of the present disclosure, each figure showing that device or cell or their assembly in an axial section;

[0029] - Figure 2 is a flow chart illustrating the logistical configuration according to which the method in the previous figures is carried out;

[0030] - Figures 3a and 3b are schematic axial sections that summarise the prerogatives of the solution in the previous figures;

[0031] - Figure 4 is a schematic axial section of a cell and auxiliary receptacle assembly according to a different aspect of the present disclosure;

[0032] - Figures 5a and 5b are schematic axial sections of respective cell and auxiliary receptacle assemblies, according to other aspects of this disclosure.

[0033] Detailed description

[0034] Referring for the time being to Figures 1 a to 1 m, as well as Figures 2, 3a and 3b, in one aspect the disclosure envisages the use of a bottle-like auxiliary receptacle 1 , e.g. cylindrical, with a bottom 1 1 , an inner compartment 12, and an inlet and outlet port 13. The device is shown in isolation in Figure 1 a, resting or otherwise supported on its bottom 11 , facing downwards, and with its port 13 facing upwards, according to a starting arrangement that characterises this solution. The port 13 has a coupling configuration suitable for reversible tight coupling with the cell opening, which will be discussed further below, this configuration obviously being inferable by a person skilled in the art, given the standards used in the construction of cells and their openings.

[0035] In an optional form, however, the auxiliary bottle-shaped receptacle 1 has in the vicinity of the port 13, and thus in the area of a radially directed bottle neck, a bore 14 which places the internal compartment 12 in communication with the outside, for the transit of air, intercepted however by a check valve 15 and capable of being connected to a suction system 5, represented schematically in Figure 3b. Again, and advantageously, the port 13 is intercepted by a system of one or more tubes 16, 17, preferably two tubes extending parallel to the axis of the bottle, a first 16 inwards, a second tube 17 outwards, in both cases for a significant extension, slightly less than the height of the bottle (distance between the bottom and the port). The tubes induce a flow separation within the port 13 in the sense that the passage section of the latter is defined by, and divided between, the passage gaps of the tubes. On the first tube 16 that protrudes externally, the aforementioned suction bore 14 opens. The liquid inlet section into the inner compartment 12 through the port 13, indicated by 13a, is in practice restricted to the passage gap of the first tube 16, the one projecting inwards, while the liquid outlet section 13b, as will become clear later, is defined by the passage gap of the second tube 17.

[0036] In this upright position, the compartment 12 of the bottle 1 is filled with electrolyte E, e.g. by means of a blowpipe 2, which is inserted into the inlet section 13a of the port 13 (Figure 1 b, arrow F1 ), the capacity of each bottle being arranged in such a way that it can accommodate at least a quantity of electrolyte E dosed for the exact filling of a single battery cell. The complete filling step is shown in Figure 1c, with the feed pipe 2 being removed. If the inlet section is not a free bore, but includes a filling valve, the supply will be provided with an appropriate connector.

[0037] At this point (Figure 1 d) a battery cell 3, a container of known characteristics that need no description except to mention its inlet opening 31 and a bottom 32, is coupled to the bottle 1 , keeping the former in an overturned position, i.e. with the opening 31 facing downwards, making the cell descend (arrow F2) and matching the aforementioned opening with the port 13, and with the second tube 17 penetrating the opening itself by entering the cell. Figure 1 e depicts the assembly of the two permanently coupled elements, the connection between port 13 and opening 31 being perfected and made tight by an appropriate reversible hydraulically sealed coupling configuration, chosen as a matter of course for a person skilled in the art based on common general knowledge, for example by means of threading and one or more gasket elements (O-ring).

[0038] In the case where, as is also exemplified in Figure 3b, there is a bore 14 with the valve 15, the reference is now to Figure 1f, there is a step of air suction and extraction from the cell, as symbolised by the arrow F3. At this point the assembly is turned upside down (Figures 1 g and 1 h), i.e. the battery cell is placed on its bottom 32 with the opening 31 facing upwards; it follows that the bottle 1 assumes an overturned position, with the bottom 1 1 at the top and the opening 13 facing downwards. By gravity, the electrolyte E begins to descend, as indicated by the arrow F5, passing through the gap of the second tube 17 (arrow F6), which is now inside the cell 1 , opening in relative proximity to the bottom 32, thus avoiding liquid spillage. Transfer into the battery cell 3 is progressive (Figure 1 i) until it is completely filled (Figure 1j), with the first tube 16 opening above the free surface of the electrolyte E in the bottle 1 acting as a vent for any residual air in the battery cell. Ultimately, as summarised by the schematic representations in Figures 3a and 3b, and speaking of means for the transit of air to or from the inner compartment 12, the valve 15 may be omitted, in which case at least the first tube 16 (Figure 3a) will be used with a venting action, while on the other hand with the provision of the bore 14 and valve 15 to suck in air, the first tube may also be omitted (Figure 3b).

[0039] During the waiting time required for the liquid to completely descend and impregnate the porous material separating the anodic and cathodic formations (“soaking”), the assembly will be stored together with several other identical assemblies in a storage region designated for this purpose. At the end of transfer, the bottle 1 is lifted (Figure 1 k, arrow F7), completely disengaging the cell 3. The latter is finally closed by inserting and sealing a plug 33 into the opening 31 (Figure 11 and finally Figure 1 m). The cell 3 can thus be sent to the further known steps of the relevant production process. The empty bottle 1 will be returned to the beginning of the cycle just described to perform the filling of a new cell.

[0040] All the steps described above are summarised by the schematic flow chart in Figure 2, which is clearly self-explanatory, noting how the continuous arrows indicate the path of the cell and the discontinuous arrows the path of the auxiliary receptacle 1 , e.g. in the bottle form just described, paths evidently running side by side in the steps in which the two components are assembled. All the steps can preferably take place in a protected environment, the perimeter of which is symbolised by the frame lines, without excluding that the overturning and transfer steps can at the very least also be performed outside this environment since the electrolyte in these steps is isolated in the assembly and cannot be contaminated.

[0041] According to another aspect, the disclosure includes the two solutions illustrated in Figures 4, 5a and 5b, which incur a certain simplification with respect to the bottle already described, but which share its conceptual principle and are nevertheless able to draw at least a significant part of its results and benefits.

[0042] In the variant shown in Figure 4, the auxiliary or service receptacle takes the form of a simple open funnel 101 with an inner compartment 112 for dosing and containing the electrolyte E, a larger port 1 11 and a smaller port representing the port 1 13, here intended only for the outlet of the liquid electrolyte. The latter, as in the previous case, has a coupling configuration suitable for stable and hydraulically sealed as well as reversible coupling, with the opening 31 of the cell 3, and integrated into the port at least one (first) vent tube 1 16, which extends within the compartment 1 12 to ensure an outlet above the free liquid surface.

[0043] The sequence of operations is, in turn, simplified and modified with respect to the one already described, however, providing for the dosing of the electrolyte E into the auxiliary receptacle by transferring it through the largest opening, in this case already overturned and after it has already been coupled to the battery cell, then waiting for the time necessary to transfer the liquid (necessarily in a protected environment), with the two components again temporarily forming a single assembly, the funnel providing a volumetric reserve capable of containing and transferring the entire volume of liquid required in a single step. The funnel is then disconnected and reused while the full cell is closed and sealed.

[0044] A further solution for which reference is made to Figures 5a and 5b recovers the expedient of an auxiliary bottle-shaped receptacle, which in this case takes on the connotation of a closed funnel 1001 , 100T, which, as in the previous case, is assembled to the battery 3 already overturned, and tends to be filled in its own inner compartment 1012, 1012’ after assembly. The device has in this case, for this purpose, in addition to a port 1013, 1013’ configured for coupling to the cell, and preferably on its own bottom 101 1 , 101 1 ’, at least one hydraulic inlet 1018, 1018’, advantageously intercepted by a valve, for connection to a pressure feeding apparatus, represented with the symbol of a dosing device 4, and at least one pneumatic outlet 1019, 1019’, which, intercepted by an active or check valve, can be intended (variant of Figure 5b) for connection to the suction means 5 for creating a vacuum, or simply (variant of Figure 5a) for evacuation of air without external suction. In the latter variant, a vent tube 1016 will necessarily be present as in the previous case, while in the variant of Figure 5b, such a tube 1016’ is optional.

[0045] From an operational point of view, this variant does not differ from the previous one, except for the fact that, in the second variant of Figure 5b, after mechanical coupling and before filling, a vacuum is created within the assembly by means of the suction means 5, and in that the electrolyte liquid E is forcibly injected, all this also with suction and filling cycles that can occur in separate or partially overlapping or completely overlapping time intervals.

[0046] Compared to the open funnel solution, this third solution has the advantage of allowing vacuum to be applied, and greater convenience and safety in terms of handling and storage. On the other hand, it is slightly more complex as reversible connections for liquid supply and air extraction must be considered. In this sense, the aspect of the present disclosure with the overturning of the assembly combines the closure of the auxiliary receptacle with ease of filling, which can be done directly from the port without the need for additional connectors.

[0047] Generally speaking, common to all aspects of the present disclosure is the advantageous possibility of filling not the battery cell but the auxiliary receptacle (bottle, open funnel, closed funnel, receptacle in general) immediately and in a very short time, and placing it with its battery in a storage location where the liquid has time to drain and complete the “soaking”, while filling proceeds gradually with other devices intended for other cells. As mentioned, the auxiliary receptacles are numerous, as filling a receptacle takes a few tenths of a second, while emptying it into the cell can take several minutes or even hours. Thanks to the provision of auxiliary devices / recipients and the rest / flow / wet storage, according to the disclosure, a short machine cycle (thus a high production rate) can be combined with an intrinsically slow process (slow impregnation of all the fine coils of porous material inside the cell). In all cases, before disassembling the auxiliary receptacle from the battery cell, a pressure compensation can be carried out by opening one of the external valves with which the receptacle may be equipped. If the cell and receptacle device have a shape that provides axial symmetry, the coupling configuration of the device is such that when the coupling is perfected, the device and cell assembly is implemented in a coaxial condition.

[0048] From the point of view of the system capable of conducting a process such as the one just described on an industrial basis, and with its accompanying auxiliary devices, it therefore provides: one or more filling and dosing stations, with means of supplying the electrolyte liquid into the receptacles and, where appropriate, means adapted to create a vacuum;

[0049] • one or more stations for mechanical coupling between cells and auxiliary devices, with appropriate handling means; this coupling station and the filling station could theoretically coincide, although this would be a less preferable solution, and in any case where required coupling will precede filling; where required this station can also provide the means for overturning the assembly, or more advantageously this operation can be carried out during a transfer step and / or in a dedicated station or sub-station;

[0050] • a storage region for the various assemblies, which accommodates them during the soaking step;

[0051] • one or more separating stations for the assemblies, if necessary equipped with handling means to place the auxiliary receptacle back in the upright position;

[0052] • advantageously, means for transporting the assemblies and devices to transfer them to and from the various stations, including transport means of the auxiliary devices separate from the respective cells from the separation station to the filling and dosing station, for further use; if theoretically feasible without risk of contamination, of exit from the protected environment (“dry room”) for the soaking step, the relevant inlet portals with an airtight chamber or the like should also be provided, but such a solution is not indicated in the context of the present disclosure.

[0053] A “station” is defined as a room or equipped place for the performance of certain operations, not necessarily fixed (e.g. they may be mounted on wheels or other transport means, even continuously).

[0054] The present disclosure has been provided hereto with reference to preferred embodiments thereof. It is to be understood that there may be other embodiments falling within the scope of protection of the claims set out below.

Claims

CLAIMS1. Method for filling a battery cell (3) with a pre-dosed amount of liquid electrolyte (E), said cell presenting an inlet opening (3) for the electrolyte, the method comprising, in sequence, the following steps: providing a receptacle-like auxiliary device (101 , 1001 ) having an inner compartment (112, 1012) configured to accommodate at least said predosed amount of liquid electrolyte (E), having a receptacle outlet port (1 13, 1013) for the electrolyte, said receptacle outlet port (1 13, 1013) comprising a reversible, hydraulically sealed coupling arrangement for coupling with said cell inlet opening (31 ), the coupling arrangement being further apt to allow a passage of air to or from said inner compartment (112, 1012); through said coupling arrangement, making an assembly between said cell (3) and said device (101 , 1001 ), with said device (101 , 1001 ) turning its receptacle outlet port (113, 1013) downward; filling with said pre-dosed amount of electrolyte (E) said receptacle-like device (101 , 1001 ); placing said assembly in a storage region for a time required for the transfer by gravity of said amount of electrolyte (E) from said receptacle device (101 , 1001 ) to said cell; decoupling said receptacle-like device (101 , 1001 ), once empty, from said cell (3) and recovering it for a new filling cycle; closing said cell (3) filled with electrolyte.

2. Method according to claim 1 , said receptacle-like device taking the form of a bottle (1001 ), the method comprising filling said receptacle device (1001 ) with liquid electrolyte through at least one hydraulic receptacle inlet (1018) formed in a wall or a bottom (101 1 ) of said bottle, and wherein said passage of air is a passage of air from said inner compartment (1012) through at least one pneumatic receptacle outlet (1019) formed in turn on a wall or a bottom (1011 ) of said bottle.

3. Method according to claim 2, wherein said passage of air further provides for a vent of air (1 16) above the free surface of said liquid electrolyte (E) poured in said predosed amount into said receptacle-like device (101 ).

4. Method according to claim 2 or 3, wherein a depression is made within said compartment (1012) through said at least one pneumatic outlet (1019).

5. Method according to claim 4, wherein the filling of said compartment (1012) electrolyte (E) is made with cycles of suction and filling at time intervals mutually distinct, partially overlapping or completely overlapping.

6. Method according to any one of claims 2 to 5, wherein said filling with liquid electrolyte of said receptacle-like device (1001 ) is obtained by connecting dosing means (4) of liquid electrolyte to said receptacle hydraulic inlet (1018).

7. A system for filling battery cells (3) with a pre-dosed amount of liquid electrolyte (E), with the method according to claim 1 , wherein a plurality of devices (1001 ) is provided, each comprising an inner compartment (1012) configured to accommodate at least said pre-dosed amount of liquid electrolyte (E), having a receptacle outlet port (1 13, 1013) for the electrolyte, said receptacle outlet port (1013) comprising a reversible, hydraulically sealed coupling arrangement for coupling with an inlet opening (31 ) of said cell (3), and in which the device further comprises air passage means (1016, 1019) apt to allow a passage of air to or from said inner compartment, the device taking the form of a bottle (1001 ), comprising at least one hydraulic receptacle inlet (1018) formed in a wall or a bottom (1011 ) of said bottle, for filling the same with liquid electrolyte (E), said air passage means comprising at least one pneumatic outlet (1019) formed in turn on a wall or bottom of said device, the system further providing: at least one mechanical coupling station for mechanical coupling between said auxiliary receptacle devices (1001 ) and said cells (3); at least one filling and dosing station, integrated with, or subsequent to, said coupling station, and comprising at least electrolyte liquid (E) supply means for feeding the liquid into said receptacle-like devices (1001 ); at least one storage region of the various assemblies, accommodating them during the time required for the transfer, of the electrolyte; at least one uncoupling station for separating the assemblies.

8. System according to claim 7, further comprising means for transporting the assemblies from said at least one coupling station to said at least one storage region, and the auxiliary receptacle-like devices (1001 ) from said at least one uncoupling station to said at least one coupling station.

9. System according to claim 7 or 8, wherein said air passage means further comprise at least one venting tube (1016) extending from said receptacle outlet port (1013) toward and within said inner compartment (1012) to provide an air vent above the free surface of said liquid electrolyte (E) poured in said pre-dosed amount.

10. System according to any of the claims from 7 to 9, wherein said at least one pneumatic outlet (1019) is configured for connection with suction means (5) to create adepression within said compartment (1012).

11. System according to claim 10, wherein said electrolyte liquid (E) supply means and said suction means (5) are configured to carry out cycles of suction and filling at time intervals mutually distinct, partially overlapping or completely overlapping.

12. System according to any one of claims from 7 to 1 1 , wherein said at least one hydraulic inlet (1018) is configured for connection of dosing means (4) of liquid electrolyte.

13. System according to any one of the claims 7 to 12, wherein said receptacle device (101 , 1001 ) and said cell (3) have shapes with axial symmetry, the coupling configuration of said receptacle outlet port (1 13, 1013) being such that the assembly of said device (101 , 1001 ) and said cell (3) is realized in a condition of coaxiality.

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