System and method for filling battery cells with liquid electrolyte.

Abstract

The present invention relates to a filling head assembly for filling a battery cell with a liquid electrolyte, the filling head assembly comprising a filling head, the filling head comprising a first fluid channel, a second fluid channel, and a valve. The inlet of the first fluid channel is connected to a pump. The inlet of the second fluid channel is connected to a vacuum pump. The outlet of the first fluid channel engages with the filling opening of the battery cell. The valve determines whether the outlet of the first fluid channel is connected to the inlet of the first fluid channel. The present invention also relates to a device comprising a filling head, a production line comprising the device, and a method for filling a battery cell with a liquid electrolyte using the device.

Description

Technical Field

[0001] Field of the Invention The present invention relates to filling a battery cell with a liquid electrolyte.

Background Art

[0002] Background Many types of electrochemical devices use porous electrodes and liquid electrolytes. A conventional lithium battery cell characterized by a composite metal oxide cathode, a composite graphite anode, a separator, and an electrolyte composed of an organic solvent and a dissolved lithium salt is an example of an electrochemical device as described above and is the most well-known and widely used example.

[0003] During the manufacture of a lithium battery cell, the electrodes and the separator are first placed inside the cell casing, and then the cell is filled with electrolyte and charged. This filling is an important step in the manufacturing process for several reasons. First, in order to ensure that the cell achieves optimal energy density, power density, and Coulombic efficiency, it is necessary to penetrate the electrolyte into all the voids in the porous electrodes. Second, it is important to sufficiently wet the porous electrodes in order to ensure uniform solid / electrolyte interface (SEI) growth and limit possible future degradation phenomena such as electrolyte decomposition and lithium dendrite formation. Third, it is necessary to advance the wetting process as quickly as possible. This is because undesired parasitic reactions occur in the uncharged cell after the electrolyte filling. For example, if the wetting time is long, it may lead to loss of active material and electrolyte, and at the same time, it may generate nucleation sites that will later cause lithium dendrites to grow.

[0004] Currently, during manufacturing, electrolytes are injected into cells with rigid casings, such as cylindrical or prismatic cells, using a fixed-volume piston, or into pouch cells with a fixed volume of electrolyte. For smaller cell sizes, the dead volume of the cell can act as a buffer for an amount of electrolyte that does not immediately penetrate the porous electrode, thus allowing the cell to fill sufficiently quickly. However, cell manufacturers are moving towards larger cell forms because these larger cells have higher volumetric and gravimetric energy densities. In larger cells, the dead volume is insufficient to accommodate the volume of electrolyte that has not yet permeated. Consequently, the rate or pace at which electrolytes are injected is determined by the rate at which the electrolyte permeates the porous electrode. Without external influences, it takes several hours for the electrolyte to sufficiently wet the porous electrode, which is unacceptably long for both the technical and economic reasons mentioned above. Therefore, three techniques are employed to enable cell filling to proceed at an acceptable pace.

[0005] Firstly, cell filling is carried out as a batch process in which multiple cells are filled in parallel. Secondly, the cells are placed in a low vacuum environment to help expel gases trapped within the porous electrodes. In a batch process, this means that multiple cells of a single batch are placed together in a vacuum chamber. Thirdly, the multiple cells are filled in multiple steps. In each step, a fixed volume of electrolyte is injected. Between steps, the cells are typically maintained in a low vacuum and high temperature environment (where a uniform pressure cycle may be applied) to enhance electrolyte wetting. Depending on the size and structure of the cells, two to three filling steps may be required (each step taking up to 30 minutes), with a vacuum wetting period of up to several hours between each filling step.

[0006] This filling process has several drawbacks. Firstly, since multiple cells are filled in parallel, the slowest cell in the batch determines the overall filling rate of the batch. As a result, if there are cells in which the electrolyte permeates particularly slowly, the entire batch filling process can be significantly prolonged. Secondly, because multiple cells are placed together in a vacuum chamber, if electrolyte overflows from one cell, all the cells in that batch become contaminated, resulting in the shutdown of the entire cell production line, even if only one injection system needs cleaning and (often required) maintenance. Typically, this shutdown is long, lasting 2 to 4 hours per day. Thirdly, a lot of energy is required to create an atmosphere in the batch processing chamber with a sufficiently low vacuum and dew point (to prevent electrolyte decomposition). Even then, the vacuum may not be low enough, potentially leading to slow electrolyte permeation or harmful side reactions. Furthermore, the vacuum wetting step requires a lot of floor space in the dry room environment portion of the manufacturing facility, which is typically expensive and energy-intensive. Finally, the filling process can take several hours to complete, potentially leading to parasitic reactions, but even then, complete wetting of the electrodes is not achieved.

[0007] Therefore, improved alternative systems and methods for filling battery cells with liquid electrolytes are still needed.

[0008] Chinese Patent Application Publication No. CN106784593B discloses a liquid injection device comprising a liquid injection cup, a liquid injection nozzle, a liquid injection pump, and a vacuum rod. The liquid injection cup is provided with an electrolyte containment cavity. The liquid injection nozzle is positioned on the liquid injection cup. A liquid injection hole is formed in the liquid injection nozzle. A liquid injection opening is formed in the liquid injection cup. The vacuum rod includes an outer rod and an inner rod. A vacuum passage is formed between the inner wall of the outer rod and the circumferential surface of the inner rod. The outer rod is movably positioned on the liquid injection cup and extends into the electrolyte containment cavity. The inner rod is movably positioned inside the outer rod like a sleeve joint. The outer rod and the inner rod each have a movement stroke that moves closer to or away from the liquid injection nozzle with respect to the liquid injection cup. At the first end of the movement stroke, the outer rod and the bottom of the liquid injection cup are aligned to seal. In addition, the vacuum passage communicates with the liquid injection hole. At the second end of the transfer stroke, the electrolyte containment cavity communicates with the liquid injection port. The inner and outer rods are aligned in a sealed state so that the vacuum passage is isolated from the liquid injection port and the electrolyte containment cavity, respectively. The liquid injection device can prevent the electrolyte from entering the vacuum passage of the vacuum rod.

[0009] Japanese Patent Publication No. JP5188730B2 discloses an injection device for a storage battery. The injection device has a hollow section through which an injection nozzle is attached to the inlet of the storage battery to inject electrolyte into the storage battery, and a suction section for exhausting the inside of the hollow section. A slider is slidably and liquid-tightly installed in the hollow section to cover an opening drilled on the lower side of the injection nozzle, and this is an injection method for performing injection using the device. [Overview of the project] [Problems that the invention aims to solve]

[0010] overview The present invention aims to improve upon the aforementioned and other drawbacks. Although the remainder of this disclosure explicitly describes the present invention in the context of battery cells, those skilled in the art will understand that the present invention is applicable to other types of electrochemical cells employing liquid electrolytes. [Means for solving the problem]

[0011] According to a first aspect of the present invention, a filling head assembly for filling a battery cell with a liquid electrolyte is disclosed, the filling head assembly comprising a filling head.

[0012] The filling head comprises a first fluid channel, a second fluid channel, and a valve. Each of the channels has an inlet and an outlet.

[0013] The inlet of the first fluid channel is adapted to be connected to a pump. The inlet of the second fluid channel is adapted to be connected to a vacuum pump.

[0014] The outlet of the first fluid channel is adapted to engage with the filling opening of the battery cell.

[0015] The outlet of the second fluid channel is located on the same side of the filling head as the outlet of the first fluid channel.

[0016] The valve is positioned such that the first fluid channel is closed when the valve is in the first position, and the first fluid channel is open when the valve is in the second position.

[0017] Preferably, the filling head is manufactured from a material compatible with the liquid electrolyte. Alternatively, the interior of the first fluid channel may be lined with a material compatible with the liquid electrolyte. Preferably, the filling head is manufactured from a material that does not exhibit substantial degassing under low vacuum conditions. Alternatively, the interiors of the first and second fluid channels may be lined with a material that does not exhibit substantial degassing under low vacuum conditions. Suitable materials for the filling head include, for example, austenitic stainless steel.

[0018] The filling head assembly functions as a fluid connection between the vacuum pump and the battery cells, and between the pump and the battery cells. A valve can shut off the first fluid channel when the vacuum pump is operating, thereby ensuring that the flow of electrolyte is cut off.

[0019] The advantage of the filling head assembly is that the volume required to reduce the pressure is significantly smaller compared to typical state-of-the-art batch processing chambers. This allows for the reliable achievement of lower pressures in a much shorter time and with much lower energy consumption.

[0020] An additional advantage of the filling head assembly is that it prevents electrolyte spillage during and after filling.

[0021] In some embodiments of the filling head assembly, the filling head further comprises a third fluid channel, which is adapted to provide a control input to the valve. For example, the valve may be controlled by pneumatic or hydraulic pressure, and the third fluid channel may function as a pneumatic or hydraulic pipe, or comprise one or more pneumatic or hydraulic pipes. Alternatively, the valve may be controlled electrically, and the third fluid channel may comprise one or more wires. Regardless of how the valve is controlled, the valve may comprise a position sensor, and the third fluid channel may comprise electrical wiring for the sensor signal.

[0022] In some embodiments of the filling head assembly, the filling head assembly further comprises a casing.

[0023] · The filling head is movably mounted within the casing. · The casing includes one or more openings to allow fluid access to the fluid channels within the filling head.

[0024] · An end face of the casing includes one of the openings and is adapted to engage an end face of the battery cell, which end face of the battery cell includes the filling opening.

[0025] · When the filling head is in a first position within the casing, the outlet of the first fluid channel is away from the filling opening, and when the filling head is in a second position within the casing, the outlet of the first fluid channel extends into the filling opening through the opening at the end face of the casing.

[0026] In some embodiments of the filling head assembly, the filling head assembly further comprises a first sealing portion mounted on an end face of the casing.

[0027] · The inner diameter of the first sealing portion is larger than the diameter of the opening at the end face of the casing.

[0028] · The first sealing portion is positioned substantially concentrically with the opening at the end face of the casing.

[0029] · The inner diameter of the first sealing portion is larger than the diameter of the filling opening. · The first sealing portion is positioned substantially concentrically with the filling opening when the end face of the casing engages the end face of the battery cell.

[0030] When the end face of the casing engages with the end face of the battery cell, the first sealing portion provides a seal between the end face of the casing and the end face of the battery cell.

[0031] Preferably, the seal is chemically inert when in contact with the liquid electrolyte. Alternatively, the seal may be chemically resistant when in contact with the liquid electrolyte. The seal may be a standard O-ring seal or an X-ring seal. Alternatively, the seal may have a specialized cross-section and / or a specialized shape. For example, the electrolyte filling opening may be rectangular or located within a rectangular embossed area. In such cases, a rectangular seal may be preferable.

[0032] The purpose of the seal is to isolate the atmosphere inside the battery cell and fluid channel from the surrounding atmosphere. The advantage of this isolation is that the volume required to reduce the internal pressure is smaller. This means that less energy is needed to reduce the pressure, and the pressure drop is achieved in a shorter time frame. To achieve this objective, the seal must be able to withstand the pressure difference between the inside of the cell and the surrounding environment without causing significant air leakage.

[0033] In some embodiments of the filling head assembly, the filling head is slidably mounted within the casing so that it can move from the first position to the second position, or from the second position to the first position.

[0034] In some embodiments of the filling head, the filling head is slidably mounted within the casing so that it can move between three or more positions within the casing.

[0035] The movement of the filling head may be entirely linear or may include an additional rotational component. This movement may be passively controlled by one or more guide surfaces or ribs, and / or actively controlled by a mechanism such as a cam.

[0036] An advantage of these embodiments is that each of the above-mentioned positions can be optimized for a specific task in the electrolyte filling process.

[0037] An additional advantage of these embodiments is that the movement of the filling head can be used to operate other operating mechanisms. For example, a valve may be operated by moving the filling head.

[0038] In some embodiments of the filling head assembly, the filling head further comprises a second sealing portion mounted on the end face of the filling head.

[0039] The inner diameter of the first sealing portion is larger than the outer diameter of the second sealing portion. The second sealing portion is positioned substantially concentrically with the first sealing portion.

[0040] The inner diameter of the second sealing portion is larger than the diameter of the outlet of the first fluid channel.

[0041] The second sealing portion is positioned substantially concentrically with the outlet of the first fluid channel.

[0042] The inner diameter of the second sealing portion is larger than the diameter of the filling opening. The second sealing portion is positioned substantially concentrically with the filling opening when the end face of the filling head engages with the end face of the battery cell.

[0043] The second sealing portion provides a seal between the end face of the filling head and the end face of the battery cell when the end face of the filling head engages with the end face of the battery cell.

[0044] Preferably, the seal is chemically inert when in contact with the liquid electrolyte. Alternatively, the seal may be chemically resistant when in contact with the liquid electrolyte. The seal may be a standard O-ring seal or an X-ring seal. Alternatively, the seal may have a specialized cross-section and / or a specialized shape. For example, the electrolyte filling opening may be rectangular or located within a rectangular embossed area. In such cases, a rectangular seal may be preferable.

[0045] The purpose of the second sealing section is to separate the atmosphere inside the battery cell and fluid channel from the volume between the filling head, casing, and battery cell during electrolyte injection into the battery. The advantage of this separation is that there is no possibility of the liquid electrolyte overflowing into the filling head assembly or onto the outer surface of the battery cell. This means that downtime and wear due to electrolyte overflow are significantly reduced. To achieve this objective, the sealing section must be able to withstand the pressure difference between the inside of the cell, which may be higher than atmospheric pressure during electrolyte injection, and the ambient volume, which may be at a low vacuum pressure.

[0046] In some embodiments of the filling head assembly, the filling head further comprises a fourth fluid channel.

[0047] The fourth fluid channel is equipped with an inlet and an outlet. The inlet of the fourth fluid channel is adapted to be connected to a gas supply system.

[0048] The outlets of the fourth fluid channel are arranged concentrically around the outlet of the first fluid channel.

[0049] A fourth fluid channel may supply shielding gas concentrically with the first fluid channel when the outlet of the first fluid channel is disengaged from the filling opening, or when the filling head assembly is disengaged from the battery cell. The shielding gas can protect the battery from moisture intrusion between the electrolyte filling step and the cell sealing step, thus eliminating the need for filling to be performed in a dry room.

[0050] An operable battery charging unit according to the present invention may comprise a charging head assembly and a battery cell as described above. In an embodiment of the operable battery charging unit according to the present invention, the battery cell is a completed cell having a charging opening having a diameter in the range of 2 mm to 10 mm, preferably in the range of 3 mm to 8 mm.

[0051] According to a second aspect of the present invention, an apparatus for filling a battery cell with a liquid electrolyte is disclosed. The apparatus is A filling head assembly according to the first aspect of the present invention, • An electrolyte reservoir configured to hold the liquid electrolyte, The apparatus further includes a pump, the outlet of which is fluid-connected to the inlet of the first fluid channel of the filling head, the inlet of which is fluid-connected to the electrolyte reservoir, the pump is adapted to pump-inject the liquid electrolyte, and the apparatus further includes The device includes a vacuum pump, the outlet of which is fluidly connected to the inlet of the second fluid channel of the filling head, the vacuum pump is adapted to reduce the pressure in the second fluid channel, the first fluid channel and the battery cell to below a predetermined pressure threshold, and the device further includes: The means for securing the battery cell in a position where the outlet of the first fluid channel can engage with the filling opening of the battery cell, and / or where the end face of the casing can engage with the end face of the battery cell, and / or where the end face of the filling head can engage with the end face of the battery cell.

[0052] Preferably, the liquid electrolyte is held in an electrolyte reservoir under an inert gas blanket.

[0053] In some embodiments of the apparatus, the apparatus further comprises a first actuator for moving a fixed battery cell. The first actuator can move the fixed battery cell from a position where the end face of the casing does not engage with the end face of the battery cell to a position where both end faces engage with each other, and can move it in the opposite direction. Preferably, the first actuator moves the battery cell assembly in parallel along a linear trajectory.

[0054] In some embodiments of the apparatus, the apparatus includes a second actuator. The second actuator moves the filling head within the casing from a position where the outlet of the first fluid channel is not engaged with the filling opening of the battery cell to a position where they are both engaged, and in the opposite direction.

[0055] In some embodiments of the apparatus, the apparatus further, • Means for measuring the amount of liquid electrolyte filled in the battery cell, The system includes means for controlling the pump.

[0056] By measuring the amount of liquid already filled in the battery, feedback can be provided to the pump controller. This allows for more precise control of the filling process, potentially resulting in faster filling times and a lower chance of electrolyte overflow.

[0057] Means for controlling the pump may include, for example, a PID controller, a state feedback controller, or any other suitable type of control algorithm known to those skilled in the art.

[0058] In some embodiments of the device, the means for measuring quantity is a weight sensor that weighs the battery cells.

[0059] Preferably, the weight sensor is mounted on a fixing means so as to support the entire weight of the battery cell once the battery cell is fixed by the device.

[0060] The advantage of using a gravimetric sensor instead of a flow sensor is that gravimetric sensors are far more accurate than flow sensors. Additional advantages include the fact that gravimetric sensors are less mechanically complex and less expensive than flow sensors. Another advantage is that gravimetric sensors do not need to be in contact with the liquid electrolyte.

[0061] In some embodiments of the device, the pump is a positive displacement pump. The advantage of using positive displacement pumps instead of non-positive displacement pumps is that the volume of electrolyte injected by the pump, or the mass of the electrolyte if it behaves as an incompressible fluid, can be directly inferred from the displacement of the pump's rotor. Positive displacement pumps have the additional advantage of being easier to control and more efficient than centrifugal or axial flow pumps at low flow rates. Furthermore, because the positive displacement pump can act as a valve, the need for a separate, dedicated valve within the filling head assembly may be eliminated.

[0062] In some embodiments of the device, the positive displacement pump is a progressive cavity pump. The advantage of using a progressive cavity pump is that the output flow of the progressive cavity pump has little to no pulsation. An additional advantage is that the progressive cavity pump can be operated in the reverse direction to aspirate and return excess electrolytes. Positive displacement pumps have the additional advantage of having linear pressure characteristics.

[0063] In some embodiments of the device, the pump is equipped with a motor encoder. The advantage of using a motor encoder is that the angular position of the pump can be determined with high resolution and precision. Because there is a relationship inherent to positive displacement pumps between the rotation of the pump and the displacement volume of the fluid, the flow of the electrolyte can be controlled with great precision.

[0064] In some embodiments of the device, the first pressure sensor is located at the inlet of the pump. In some embodiments of the apparatus, the second pressure sensor is located at the outlet of the pump or inside the first fluid channel.

[0065] In some embodiments of the apparatus, the third pressure sensor is located at the outlet of the vacuum pump or inside the second fluid channel.

[0066] The advantage of using pressure sensors is that these pressure sensors can provide additional feedback input for controlling pumps and / or vacuum pumps.

[0067] In some embodiments of the apparatus, a second valve is located between the outlet of the vacuum pump and the inlet of the second fluid channel.

[0068] An advantage of these embodiments is that a second valve can be used to return the internal volume of the filling head assembly to the ambient pressure that may be required to disengage the battery cells from the filling head assembly.

[0069] A third aspect of the present invention is disclosed, which is a production line for filling battery cells with a liquid electrolyte. The production line comprises an apparatus according to the second aspect of the present invention and an automatic actuator.

[0070] The automatic actuator is configured to position and place battery cells that are not filled with electrolyte into the device.

[0071] The device is configured to fill the battery cell with a liquid electrolyte. The automatic actuator is configured to remove the battery cell from the device once the battery cell has been filled.

[0072] Filling battery cells with liquid electrolyte typically takes much longer than lifting and moving the battery cells. Therefore, the number of automated actuators a production line can have may be less than the number of filling devices. For example, one automated actuator may be able to supply battery cells to up to 24 filling devices and remove battery cells from up to 24 filling devices. Those skilled in the art will understand that the optimal number of filling devices per automated actuator depends on the expected filling time of the battery cells and, consequently, on the type and size of the cells.

[0073] In some embodiments of the production line, one or more devices are organized in a modular manner. Preferably, this modular arrangement includes one or more modular slides, one or more cages (mechanical frames on which filling devices are arranged), and one or more airlocks. For example, the modular equipment may have airlocks that can be opened at both ends. One side of the airlock may be a dry room environment, and the other side may be the ambient environment. One or more cages may be installed inside the airlock. Each cage contains one or more filling devices. These filling devices are preferably installed on a movable slide within the cage. For example, the above-described filling devices can be organized into four cages, each cage holding six devices arranged in pairs on a movable slide.

[0074] An advantage of this embodiment is that these devices can move between two or more distinct positions. For example, a first position may correspond to the normal functioning of the device. Therefore, when the device is in the first position, the automatic actuator may equip the device with battery cells. A second position may correspond to a maintenance position or a calibration position. When in this position, the automatic actuator may not equip the device with battery cells. For example, to perform maintenance on one filling device, the dry room side of the airlock is closed. Then, the ambient environment side of the airlock is opened, and the filling device mounted on a movable slide is retracted from the airlock. When the applicable filling device (or applicable pair) is positioned outside the airlock for maintenance, the ambient environment side may be closed and the dry room side may be opened again, so that the remaining filling devices can continue to operate in a controlled atmosphere. This may allow a human operator to intervene for maintenance or repair of the device without having to enter the room where the battery cells are filled. This reduces the risk of cell contamination and also reduces the safety risk to the human operator.

[0075] In addition, since each filling device is controlled individually, devices that are not undergoing maintenance can continue to function and remain in a dry atmosphere. This ensures that the cell filling process is not interrupted, even during maintenance, or in the event of a malfunction or electrolyte leak.

[0076] A fourth aspect of the present invention is disclosed, a method for filling a battery cell with a liquid electrolyte using an apparatus according to the second aspect of the present invention. This method is a. A step of positioning the battery cell, b. The steps of engaging the outlet of the first fluid channel with the filling opening of the battery cell, or engaging the end face of the casing with the end face of the battery, c. Optionally, the step of operating the pump in the reverse direction to aspirate back any electrolytes that may remain in the first fluid channel, d. The step of blocking the first fluid channel by positioning the valve at the first location, e. The step of operating the vacuum pump to reduce the pressure in the second fluid channel, the first fluid channel, and the battery cell to below a predetermined pressure threshold, f. Optionally, if in step (b) the end face of the casing is engaged with the end face of the battery, the step of guiding the filling head to the second position in the casing, thereby extending the outlet of the first fluid channel into the filling opening of the battery cell, g. The step of positioning the valve in the second position, h. The step of operating the pump to fill the battery cell with liquid electrolyte, i. A step of making the pressure in the first fluid channel, the second fluid channel, and the battery cell equal to the ambient pressure, j. Optionally, if in step (e) the filling head is guided to the second position in the casing, the step of guiding the filling head to the first position in the casing, k. Disengaging the outlet of the first fluid channel from the filling opening of the battery cell, or disengaging the end face of the casing from the end face of the battery, l. The step of removing the battery cell.

[0077] In some embodiments of the method, the method further includes the step of reversing the operation of the pump after filling the battery cell with the liquid electrolyte.

[0078] The step of reversing the pump can serve multiple purposes. By reversing the pump, the pressure in the battery cell, which may have risen due to the pumping action, can be normalized. Preferably, the battery is overfilled with reverse electrolyte to compensate for the electrolyte volume removed while the pump is reversing. Alternatively, by reversing the pump, excess electrolyte may be aspirated back in, which can prevent contamination of the battery cell or filling head assembly when the outlet of the first fluid channel is disengaged from the filling opening. Optionally, a valve is placed in the first position after the step of reversing the pump to prevent electrolyte from overflowing.

[0079] In some embodiments of the method, the method further, The steps include: • While filling the battery cell with liquid electrolyte, periodically measuring the amount of electrolyte filled into the battery cell; The process includes the step of controlling the pump to ensure proper filling of the battery cells.

[0080] In some embodiments of the method, the method further, The steps include: periodically measuring the pressure inside the pump outlet and / or the outlet of the first fluid channel while filling the battery cell with liquid electrolyte; The process includes the step of controlling the pump to ensure that the pressure setpoint is maintained or not exceeded.

[0081] In some embodiments of the method, the method further includes a step of calibrating the pump. Such calibration may include, for example, simultaneously measuring the weight of the electrolyte actually pumped into the cell (which may be done by measuring the cell before and after filling) and the amount of electrolyte pumped in according to the pump model and / or pump sensor. Based on these measurements, the deviation between the measured filling weight and the estimated filling amount can be tracked over time, and the parameters of the control algorithm can be adjusted to compensate for wear, tolerances, and environmental impacts.

[0082] This calibration may be performed cell by cell or periodically. Incentives that may trigger the calibration process include, for example, the completion of a predetermined number of filling cycles, a predetermined filling volume, detection of deviations by a controller, or human intervention. The sample frequency for the calibration procedure may be adjusted. [Brief explanation of the drawing]

[0083] [Figure 1a] This figure schematically shows one embodiment of a filling head assembly according to the present invention. [Figure 1b] This figure schematically shows one embodiment of a filling head assembly according to the present invention. [Figure 1c] This figure schematically shows one embodiment of a filling head assembly according to the present invention. [Figure 1d] This figure schematically shows one embodiment of a filling head assembly according to the present invention. [Figure 2] This figure schematically shows one embodiment of a device according to the present invention. [Modes for carrying out the invention]

[0084] Detailed explanation This disclosure describes specific embodiments that are illustrative but should not be construed as limiting. It will be understood that this disclosure is not limited by what is specifically illustrated and / or described, and that alternative or modified embodiments may be developed in light of the teachings of this disclosure as a whole. The drawings described are illustrative and not limiting.

[0085] Throughout this description, where the terms “one embodiment” or “embodiment” are used, it means that certain features, structures, or characteristics described in relation to an embodiment are included in one or more embodiments of this disclosure. Therefore, the phrases “in one embodiment” or “in an embodiment” appearing in various places throughout this specification do not necessarily all refer to the same embodiment, although they may refer to the same embodiment. Furthermore, certain features, structures, or characteristics may be combined in any preferred manner in one or more embodiments, as may become apparent to those skilled in the art from this disclosure.

[0086] Specific features, structures, or characteristics are indicated by reference numbers in the figures. Not all features are shown in every figure to avoid overcrowding the figures. Conversely, not all features shown in a particular figure are explained within the context of that specific figure to avoid overcrowding the specification.

[0087] Finally, wherever ordinal numbers such as “first,” “second,” etc. are used throughout this disclosure, they do not, conversely, imply any hierarchical relationship (not in terms of importance, location, or time) between the features on which these ordinal numbers are used, unless explicitly stated. These ordinal numbers simply serve to distinguish features, characteristics, or structures that are different but similar.

[0088] Figure 1a schematically shows an embodiment of a filling head assembly 100 according to the present invention. The assembly comprises a filling head 200 that is movably mounted inside a casing 300. In the embodiment of Figure 1a, the filling head 200 is in a first position within the casing 300.

[0089] The filling head 200 includes a first fluid channel 210, a second fluid channel 220, and a third fluid channel 230. The inlet of the first fluid channel 210 is connected to the outlet of the pump 510. The inlet of the second fluid channel 220 is connected to the outlet of a vacuum pump (not shown in Figure 1a). A valve 240 is located between the pump 510 and the outlet 212 of the first fluid channel 210. In the embodiment of Figure 1a, the valve 240 is in a first position so as to block the first fluid channel 210.

[0090] Figure 1b schematically illustrates how the end face 310 of the casing 300 engages with the end face 401 of the battery cell 400. Preferably, this engagement is performed by a first actuator (not shown) that moves the battery cell 400 toward the filling head assembly. The first actuator is connected to means for securing the cell (not shown). Preferably, the first actuator is a linear actuator. Preferably, the first actuator is configured to move the battery cell between two positions: one position in which the cell is not engaged with the filling head assembly, and another position in which the cell is engaged with the filling head assembly. Preferably, the movement of the battery cell is a parallel movement. Alternatively, this engagement may be performed by a second actuator (not shown) that moves the filling head assembly toward the battery cell. The casing includes a funnel 312, which ensures that the battery cell 400 is centered and held in place relative to the filling head assembly when engaged. The first sealing portion 311 is compressed between the end face 310 of the casing and the end face 401 of the battery, surrounding the filling opening 402 of the battery cell 400 and the opening in the casing.

[0091] In the situation shown in Figure 1b, the valve 240 is still in the first position. In this situation, the vacuum pump can be operated to reduce the pressure inside the battery cell 400 to below a predetermined pressure threshold. Such a pressure reduction reduces the amount of gas trapped in the porous electrodes of the battery cell, thereby allowing the electrolyte to penetrate these electrodes more quickly. Preferably, the pressure inside the battery cell is reduced to a low vacuum level. For example, the pressure may be reduced to below 50 mbar. Inevitably, in order to reduce the pressure inside the battery cell 400, the pressure inside the first and second fluid channels, as well as the pressure inside the gap 330 between the filling head 200 and the casing 300, must also be reduced. The first seal 311 must be able to withstand the pressure difference between the area around the battery cell and filling head assembly, which will generally be atmospheric pressure, and the area inside the battery cell and filling head assembly, which will be a low vacuum pressure.

[0092] In the situation shown in Figure 1c, the filling head 200 is in a second position within the casing 300. Preferably, the movement of the filling head from the first position to the second position, and vice versa, is controlled by a second actuator (not shown) fixedly connected to the filling head and a compression spring 331. The compression spring 331 is mounted to guide the filling head 200 to the first position within the casing 300, while the second actuator is designed to guide the filling head 200 to the second position within the casing by acting against the force applied by the spring. The actuator can be any known type of pneumatic, hydraulic, or electromechanical actuator. The movement of the filling head 200 within the casing 300 is limited and guided by a guide surface 332. The permitted movement may be entirely linear or may have an additional rotational component. The third sealing portion 333 seals the lateral contact surface between the filling head 200 and the casing 300, and together with the first sealing portion 311, ensures that a low vacuum pressure is maintained.

[0093] When the filling head 200 is in the second position, the outlet of the first fluid channel extends into the filling opening 402 of the battery cell. The second seal portion 251 surrounding the outlet of the first fluid channel is compressed between the end face of the filling head and the end face of the battery cell. The main purpose of the second seal portion is to ensure that the electrolyte does not overflow during the cell filling process.

[0094] In Figure 1d, the valve 240 is positioned in its second location. In this position, the pump 510 is fluidly connected to the outlet of the first fluid channel 210. By operating the pump, the liquid electrolyte can be injected into the battery cell. The liquid electrolyte cannot overflow due to the provision of the second seal 251. The second seal 251 must be able to withstand the pressure difference between the inside of the battery cell and the first fluid channel (where the pressure may rise due to the filling process) and the volume 330, which may still be at a low vacuum pressure.

[0095] Figure 2 schematically shows an embodiment of an apparatus according to the present invention. The apparatus 500 comprises a filling head assembly 100 and a pump 510. The pump 510 is fixedly mounted on the filling head, which is part of the filling head assembly. A second actuator 550 is fixedly mounted on the pump and the filling head, and these parts are connected to the upright section 530. The apparatus further comprises means for fixing the battery cell 520. In the embodiment of Figure 2, the means for fixing is a holder that restricts the downward or lateral translation of the battery cell but does not exert a clamping force on the cell. A first actuator 540 is fixedly mounted on the means for fixing, and this part is connected to the upright section 530.

[0096] During operation, the battery cell 400 is positioned within the means 520 for securing it. The first actuator 540 can move the battery cell upward to engage with the filling head assembly. The second actuator 550 can move the filling head downward together with the pump to engage with the filling opening of the battery cell. [Explanation of Symbols]

[0097] Reference sign

[0098] [Table 1]

Claims

1. A filling head assembly (100) for filling a battery cell (400) with a liquid electrolyte, wherein the filling head assembly (100) comprises a filling head (200), a. The filling head (200) comprises a first fluid channel and a second fluid channel (210, 220) and a valve (240), b. Each of the fluid channels (210, 220) is provided with an inlet and an outlet. c. The inlet of the first fluid channel (210) is adapted to be connected to a pump (510), d. The inlet of the second fluid channel (220) is adapted to be connected to a vacuum pump. e. The outlet of the first fluid channel (210) is fitted to engage with the filling opening (402) of the battery cell (400), f. The outlet of the second fluid channel (220) is located on the same side of the filling head (200) as the outlet of the first fluid channel (210). g. A filling head assembly (100) wherein the valve (240) is positioned such that the first fluid channel (210) is closed when the valve (240) is in a first position, and the first fluid channel (210) is open when the valve (240) is in a second position.

2. The filling head assembly (100) further comprises a casing (300), a. The filling head (200) is movably mounted within the casing (300), b. The casing (300) includes one or more openings to allow fluid to access the fluid channels (210, 220) of the filling head (200), c. An end face (310) of the casing (300), the end face (310) of the casing includes one of the openings and is fitted to engage with an end face (401) of the battery cell (400), the end face (401) of the battery cell includes the filling opening (402), d. The filling head assembly (100) according to claim 1, wherein when the filling head (200) is in a first position within the casing (300), the outlet of the first fluid channel (210) is away from the filling opening (402), and when the filling head (200) is in a second position within the casing (300), the outlet of the first fluid channel (210) extends into the filling opening (402) through the opening at the end face (310) of the casing.

3. The filling head assembly (100) further comprises a first sealing portion (311) mounted on the end face (310) of the casing, a. The inner diameter of the first sealing portion (311) is larger than the diameter of the opening in the end face (310) of the casing. b. The first sealing portion (311) is positioned substantially concentrically with the opening, c. The inner diameter of the first sealing portion (311) is larger than the diameter of the filling opening. d. The first sealing portion (311) is positioned substantially concentrically with the filling opening when the end face (310) of the casing engages with the end face of the battery cell. e. The filling head assembly (100) according to claim 2, wherein when the end face (310) of the casing engages with the end face of the battery cell, the first sealing portion (311) provides a seal between the end face (310) of the casing and the end face of the battery cell.

4. The filling head assembly (100) according to claim 2 or 3, wherein the filling head (200) is slidably mounted within the casing (300) so as to be able to move from the first position to the second position, or from the second position to the first position.

5. The filling head assembly (100) further comprises a spring (331), the spring (331) being mounted between the filling head (200) and the casing (300), according to claim 4.

6. A filling head assembly (100) according to any one of claims 2 to 5, wherein the filling head assembly (100) further comprises a second sealing portion (251) mounted on the end face of the filling head, a. The inner diameter of the first sealing portion (311) is larger than the outer diameter of the second sealing portion (251). b. The second sealing portion (251) is positioned substantially concentrically with the first sealing portion (311), c. The inner diameter of the second sealing portion (251) is larger than the diameter of the outlet of the first fluid channel (210). d. The second sealing portion (251) is positioned substantially concentrically with the outlet of the first fluid channel (210), e. The inner diameter of the second sealing portion (251) is larger than the diameter of the filling opening (402), f. The second sealing portion (251) is positioned substantially concentrically with the filling opening (402) when the filling head end face engages with the end face of the battery cell. g. The second sealing portion (251) is a filling head assembly (100) that provides a seal between the filling head end face and the end face (401) of the battery cell when the filling head end face engages with the end face (401) of the battery cell.

7. An operable battery charging unit comprising a charging head assembly (100) according to any one of claims 1 to 6 and the battery cell (400).

8. The operable battery filling unit according to claim 7, wherein the battery cell (400) is an assembled cell having a filling opening (402) having a diameter in the range of 2 mm to 10 mm, preferably in the range of 3 mm to 8 mm.

9. An apparatus for filling a battery cell (400) with a liquid electrolyte, wherein the apparatus is a. A filling head assembly (100) according to any one of claims 1 to 3, b. An electrolyte reservoir configured to hold the liquid electrolyte, c. A pump, the outlet of which is fluid-connected to the inlet of the first fluid channel (210) of the filling head (200), the inlet of which is fluid-connected to the electrolyte reservoir, the pump is adapted to pump-inject the liquid electrolyte, and the apparatus further includes d. Including a vacuum pump, the outlet of the vacuum pump is fluidly connected to the inlet of the second fluid channel (220) of the filling head (200), and the vacuum pump is adapted to reduce the pressure in the second fluid channel (220), the first fluid channel (210), and the battery cell (400) to below a predetermined pressure threshold, and the device further includes, e. An apparatus comprising means for securing the battery cell (400) in a position where the outlet of the first fluid channel (210) can engage with the filling opening (402) of the battery cell (400), and / or where the end face (310) of the casing can engage with the end face (401) of the battery cell, and / or where the end face of the filling head can engage with the end face (401) of the battery cell.

10. The apparatus according to claim 9, further comprising one or more actuators for changing the position of the filling head (200) within the casing (300) from a first position to a second position and / or from the second position to the first position, and / or for changing the position of the battery cell (400) from a first position to a second position and / or from the second position to the first position.

11. The aforementioned device further, a. Means for measuring the amount of liquid electrolyte filled in the battery cell (400), b. The apparatus according to claim 9 or 10, further comprising means for controlling the pump (510).

12. The apparatus according to any one of claims 9 to 11, wherein the pump (510) is a positive displacement pump.

13. The apparatus according to claim 12, wherein the pump (510) is a progressive cavity pump.

14. The apparatus according to any one of claims 9 to 13, further comprising a second valve between the outlet of the vacuum pump and the inlet of the second fluid channel (220).

15. A production line for filling a battery cell (400) with a liquid electrolyte, wherein the production line comprises the apparatus described in any one of claims 9 to 14 and an automatic actuator. a. The automatic actuator is configured to lift the battery cell (400) that is not filled with electrolyte and place it inside the device. b. The apparatus is configured to fill the battery cell (400) with a liquid electrolyte, c. A production line in which the automatic actuator is configured to remove the battery cell (400) from the device when the battery cell (400) has been filled.

16. A method for filling a battery cell (400) with a liquid electrolyte using the apparatus described in any one of claims 9 to 14, wherein the method is: a. A step of positioning the battery cell (400), b. The steps of engaging the outlet of the first fluid channel (210) with the filling opening (402) of the battery cell (400), or engaging the end face of the casing with the end face (401) of the battery, c. Optionally, the step of operating the pump (510) in the reverse direction to aspirate back any electrolytes that may remain in the first fluid channel (210), d. The step of blocking the first fluid channel (210) by positioning the valve (240) in the first position, e. The step of operating the vacuum pump (510) to reduce the pressure in the second fluid channel (220), the first fluid channel (210), and the battery cell (400) to below a predetermined pressure threshold, f. Optionally, in step (b), if the end face of the casing is engaged with the end face (401) of the battery, the step of guiding the filling head (200) to the second position in the casing (300) thereby extending the outlet of the first fluid channel (210) into the filling opening (402) of the battery cell (400), g. The step of positioning the valve (240) in the second position, h. The step of operating the pump (510) to fill the battery cell (400) with the liquid electrolyte, i. The steps of making the pressure in the first fluid channel (210), the second fluid channel (220), and the battery cell (400) equal to the ambient pressure, j. Optionally, if in step (e) the filling head (200) is guided to the second position in the casing (300), the step of guiding the filling head (200) to the first position in the casing (300) k. Disengaging the outlet of the first fluid channel (210) from the filling opening (402) of the battery cell (400), or disengaging the end face of the casing from the end face (401) of the battery, l. A method comprising the step of removing the battery cell (400).

17. The method according to claim 16, further comprising the step of filling the battery cell (400) with the liquid electrolyte and then operating the pump (510) in reverse.

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