Liquid injection device and liquid injection method

Abstract

The present invention simplifies a configuration for reducing pressure and injecting a liquid into a storage battery. A liquid injection method includes: a step for inserting a nozzle section 11 of a liquid injection syringe 10 into a cell opening 5 opened in an outer can 2, the nozzle section 11 being provided with a liquid injection port 12 that supplies an electrolytic solution EL into the interior of the outer can and a suction port 14 that is in communication with a suction path 15 connected to an external pump VP for decompressing the outer can 2; a step for decompressing the interior of the outer can 2 via the suction port 14 and the suction path 15; a step for supplying the electrolytic solution EL to a liquid storage chamber 13 that is partitioned in an airtight manner from the suction path 15 in the liquid injection syringe 10; a step for decompressing the liquid storage chamber 13 separately from the interior of the outer can 2; a step for expanding the volume of the suction path 15 by operating a volume varying mechanism 16 provided on the suction path 15 in the liquid injection syringe 10, and thereby further decompressing the interior of the outer can 2 that is in communication with the suction path 15 via the suction port 14; and a step for injecting, into the outer can 2, the electrolytic solution EL in the liquid storage chamber 13.

Description

Liquid injection device and liquid injection method

[0001] The present disclosure relates to a liquid injection device and a liquid injection method for injecting an electrolyte into a container in a manufacturing process for a battery cell or the like.

[0002] Battery cells such as lithium-ion secondary batteries contain a positive electrode, a negative electrode, a separator, an electrolyte, and other components in an outer can that serves as the container. The manufacturing process for such battery cells requires efficient injection of the electrolyte. Known methods for injecting the electrolyte into the outer can include an open-type injection method and a closed-type injection method. In the closed-type method, an electrode assembly in which the positive and negative electrodes and the separator are wound or stacked is inserted into the outer can, the opening of the outer can is closed with a lid, and the electrolyte is filled through a filling port provided in the lid, which is then sealed.

[0003] A known method for injecting electrolyte into an outer can is to reduce the pressure inside the outer can housing the electrode assembly and supply the electrolyte under reduced pressure. This method involves sucking the electrolyte into the depressurized outer can like a dropper, injecting and filling the electrolyte. This method shortens the injection and filling time because the electrolyte is sucked into the outer can maintained at negative pressure.

[0004] However, it is difficult to replace all of the air in the outer can with the electrolyte simply by reducing the pressure, and fine bubbles still remain in the gaps between the electrode assemblies, which are difficult to remove. Specifically, it is conceivable to make it easier to inject the electrolyte into the outer can by separately reducing the pressure inside the outer can and the syringe that injects the electrolyte into the outer can, and then further reducing the pressure inside the outer can to increase the degree of vacuum. However, while booster pumps or the like are generally used to increase the degree of vacuum, such pumps have the problem of complex piping and an increased size of the injection device.

[0005] Patent re-publication No. WO14 / 006660

[0006] One object of one aspect of the present disclosure is to provide a liquid injection device and a liquid injection method that simplify the configuration when injecting liquid by reducing pressure. Another object of another aspect is to provide a liquid injection device and a liquid injection method that improve efficiency during liquid injection. Note that the description of these objects does not preclude the existence of other objects. Furthermore, it is not necessary for one aspect of the present disclosure to solve all of these objects. Furthermore, other objects can be extracted from the description of the specification, drawings, claims, etc. of the present disclosure. Means for solving the problem and effects of the invention

[0007] A liquid injection method according to a first aspect of the present disclosure is a liquid injection method for injecting an electrolyte solution into an outer can of an electricity storage device, the method including the steps of: inserting a nozzle portion of an injection syringe, the nozzle portion having an injection port for supplying the electrolyte solution into the interior of the outer can and a suction port connected to a suction path connected to an external pump for depressurizing the outer can, into a cell opening opened in the outer can; reducing the pressure inside the outer can through the suction port and the suction path; supplying the electrolyte solution to a liquid reservoir chamber airtightly separated from the suction path within the injection syringe; reducing the pressure in the liquid reservoir chamber separately from the interior of the outer can; operating a volume variable mechanism provided on the suction path within the injection syringe to expand the volume of the suction path, thereby further reducing the pressure inside the outer can, which is connected to the suction path via the suction port; and injecting the electrolyte solution in the liquid reservoir chamber into the outer can. This allows the volume variable mechanism provided in the injection syringe to be operated to further reduce the pressure inside the outer can, which is already reduced in pressure, thereby enabling the electrolyte to be efficiently injected into the outer can. In particular, additional pressure reduction is possible with the simple configuration of the volume variable mechanism incorporated into the injection syringe, without the need for complex piping such as a booster pump. Furthermore, by incorporating the volume variable mechanism into the injection syringe, there is no loss due to the length of the piping, as with a booster pump, and the effect of efficiently increasing the degree of vacuum can be achieved.

[0008] A second aspect of the liquid injection method is the above aspect, further comprising the step of airtightly closing the liquid injection port so that the liquid reservoir chamber and the interior of the outer can are not in communication with each other prior to the step of depressurizing the interior of the outer can, thereby airtightly separating the liquid reservoir chamber and the interior of the outer can and making it possible to depressurize them separately.

[0009] Furthermore, in a third aspect of the liquid injection method, in any of the above aspects, the step of airtightly closing the liquid injection port includes moving a syringe shaft extended within the liquid injection syringe to close a path leading to the liquid injection port with the tip of the syringe shaft. This makes it possible to close the liquid injection port with a simple mechanism of moving the syringe shaft.

[0010] In a fourth aspect of the liquid injection method, in any one of the above aspects, the step of supplying the electrolyte to the liquid reservoir chamber is performed with the liquid reservoir chamber open, thereby enabling the electrolyte to be smoothly supplied to the liquid reservoir chamber under atmospheric pressure.

[0011] Furthermore, in the liquid injection method according to a fifth aspect, in any one of the above aspects, the step of supplying the electrolyte to the liquid reservoir chamber is performed with the rear end of the liquid injection syringe being open to the liquid reservoir chamber.

[0012] A sixth aspect of the liquid injection method is any one of the above aspects, wherein the step of depressurizing the liquid reservoir chamber is performed in a state in which the liquid injection syringe is closed by a syringe cup inserted from the rear end thereof.

[0013] Furthermore, in a seventh aspect of the liquid injection method, in any of the above aspects, the step of further reducing the pressure inside the outer can is carried out by expanding the volume of the suction path with the volume varying mechanism while maintaining the volume of the liquid reservoir chamber at a constant volume with the syringe cup.

[0014] Furthermore, in an eighth aspect, in any of the above aspects, the liquid injection method further includes, following the step of injecting the electrolyte solution in the liquid reservoir chamber into the outer can, a step of reducing the volume of the liquid reservoir chamber of the injection syringe to pressurize the inside of the outer can.

[0015] Furthermore, in accordance with a ninth aspect, in any one of the above aspects, the liquid injection method further includes, following the step of pressurizing the interior of the outer can, the step of opening the liquid reservoir chamber and the suction path to atmospheric pressure.

[0016] Furthermore, in the liquid injection method according to a tenth aspect, in any one of the above aspects, the power storage device is a lithium ion secondary battery.

[0017] Furthermore, according to an eleventh aspect, there is provided a liquid injection device for injecting electrolyte into an outer can of an electrical storage device, the liquid injection device comprising: an injection syringe including a nozzle portion having a liquid injection port communicating with the liquid reservoir chamber and a suction path therein, the nozzle portion having a liquid injection port for supplying the electrolyte into the interior of the outer can and a suction port communicating with the suction path at one end; a pump communicating with the suction path at the other end for depressurizing the outer can; and a tank communicating with the liquid reservoir chamber and for storing the electrolyte, the liquid injection syringe having a volume variable mechanism provided on the suction path. With this configuration, the volume variable mechanism provided in the liquid injection syringe can be operated to further reduce the pressure inside the outer can, which is already reduced in pressure, thereby enabling efficient injection of electrolyte into the outer can. In particular, the additional pressure reduction is possible without requiring complex piping such as a booster pump, and is achieved with a simple configuration of a volume variable mechanism incorporated in the liquid injection syringe. Furthermore, by incorporating a volume-adjusting mechanism into the injection syringe, there is no loss due to the length of the piping, as occurs with a booster pump, and the degree of vacuum can be increased efficiently.

[0018] In a twelfth aspect of the liquid injection device, in any of the above aspects, the liquid injection syringe includes a movable syringe shaft extending therein. The syringe shaft has a closing portion at its tip that closes a path leading to the liquid injection port, and the closing portion can be moved to open and close the path leading to the liquid injection port. With this configuration, the liquid injection port can be closed by simply moving the syringe shaft, and the liquid reservoir chamber and the interior of the outer can can be airtightly separated and the pressure therein can be reduced individually.

[0019] A thirteenth aspect of the liquid injection device is any of the above aspects, wherein the liquid injection syringe has an open rear end of the liquid reservoir chamber, and a syringe cup is slidably inserted into the rear end of the liquid injection syringe. With this configuration, the volume of the liquid reservoir chamber can be varied by using the syringe cup.

[0020] Furthermore, in accordance with a fourteenth aspect of the present invention, in the liquid injection device of any one of the above aspects, the power storage device is a lithium ion secondary battery.

[0021] Furthermore, a fifteenth aspect of the present invention provides an injection syringe for use in an injection device for injecting electrolyte into the outer can of an electrical storage device. The injection syringe has a liquid reservoir chamber and a suction path defined therein, a nozzle portion connected to the liquid reservoir chamber and including an injection port for supplying the electrolyte into the outer can, and a suction port connected at one end to the suction path, and a volume-adjusting mechanism is provided on the suction path. With this configuration, the pressure inside the outer can, which is already reduced, can be further reduced by operating the volume-adjusting mechanism provided in the injection syringe, thereby enabling efficient injection of electrolyte into the outer can. In particular, this does not require complex piping such as a booster pump, and the simple configuration of the volume-adjusting mechanism incorporated into the injection syringe enables additional pressure reduction. Furthermore, incorporating the volume-adjusting mechanism into the injection syringe efficiently increases the degree of vacuum without the loss due to the piping length that occurs with a booster pump.

[0022] 1 is a schematic diagram showing a liquid injection device according to embodiment 1. FIG. 2 is a schematic diagram showing a liquid injection device according to embodiment 2. FIG. 3 is a schematic diagram showing a liquid injection device according to embodiment 3.

[0023] The present disclosure will be described in more detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper," "lower," and other terms including these terms) will be used as necessary. However, the use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present disclosure. Furthermore, parts that appear with the same reference numerals in multiple drawings indicate the same or equivalent parts or components.

[0024] Furthermore, the embodiments shown below are specific examples of the technical ideas of the present disclosure, and are not intended to limit the present disclosure to the following. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative and not to limit the scope of the present disclosure. Furthermore, the content described in one embodiment can also be applied to other embodiments. Furthermore, the sizes and positional relationships of components shown in the drawings may be exaggerated to clarify the explanation. (Secondary Battery 1)

[0025] The following description will be given taking a lithium-ion secondary battery as an example of an electricity storage device to which an electrolyte is injected, and to which the liquid injection device and liquid injection method are applied. The lithium-ion secondary battery includes a rectangular outer can 2, an electrode assembly housed in the outer can 2, and an electrolyte housed in the outer can 2. The outer can 2 has a case body in the shape of a rectangular cylinder with a bottom and a plate-like lid that closes the opening of the case body. The case body and the lid form the wall of the outer can 2. The lid has a cell opening that penetrates the lid in the plate thickness direction. The secondary battery 1 of this embodiment is a prismatic battery with a rectangular appearance. Note that the present disclosure is not limited to prismatic batteries as electricity storage devices, and can also be applied to batteries with cylindrical outer cans.

[0026] The electrode assembly includes one or more positive electrodes, one or more negative electrodes, and one or more separators. The electrode assembly has a layered structure in which positive and negative electrodes are stacked with a separator interposed between them and insulated from each other. The positive and negative electrodes each include a rectangular sheet-shaped current collector, active material layers on both sides of the current collector, and a current collector tab protruding from one side of the current collector. The current collector tab does not include an active material layer and is composed of the current collector itself. The electrode assembly includes a tab group in which one or more current collector tabs are stacked with the same polarity. While an example in which multiple sheets are stacked as the current collector has been described, a single-strand current collector in which the electrode is wound in an inverted manner may also be used.

[0027] Next, a method for manufacturing the secondary battery 1 will be described. The method for manufacturing the secondary battery 1 includes a liquid injection process in which an electrolyte is injected through a cell opening into the outer can 2 containing the electrode assembly, a temporary sealing process in which the cell opening is temporarily sealed with a temporary sealing member, and an initial charge / discharge process in which the outer can 2 is constrained by a restraining jig and initial charge / discharge is performed. The initial charge / discharge process in this embodiment comprises a conditioning process and an aging process. In the conditioning process, initial charging is performed. Note that, depending on the specifications of the secondary battery 1, multiple charge / discharge cycles may be repeated. After the conditioning process, in the aging process, the secondary battery 1 is heated to a predetermined aging temperature in a thermostatic bath and left for a predetermined time. After the initial charge / discharge process, the restraint of the outer can 2 by the restraining jig is released. [Liquid Injection Device 100]

[0028] 1 shows a liquid injection device 100 that injects an electrolyte into an outer can 2 of a secondary battery 1. The liquid injection device 100 shown in this figure includes a liquid injection syringe 10, a pump VP, and a tank TK. (Liquid Injection Syringe 10)

[0029] The interior of the injection syringe 10 is divided into a liquid reservoir chamber 13 and a suction path 15. The liquid reservoir chamber 13 is a space for temporarily storing the electrolyte solution EL. The liquid reservoir chamber 13 is also connected to a tank TK and receives a supply of the electrolyte solution EL from the tank TK.

[0030] The suction path 15 is a path that is connected at one end (lower part in the figure) to the inside of the outer can 2 via the suction port 14, and at the other end (upper part in the figure) to the pump VP, and is used to reduce the pressure inside the outer can 2 by suctioning with the pump VP.

[0031] The injection syringe 10 is provided with a nozzle 11 at its tip (lower in the figure). The rear end (upper in the figure) is at least partially open. The nozzle 11 includes an injection port 12 and a suction port 14. The injection port 12 is connected to a liquid reservoir chamber 13. Electrolyte solution EL temporarily stored in the liquid reservoir chamber 13 is supplied to the interior of the outer can 2 through the injection port 12. The suction port 14 is connected to a suction path 15, which sucks air from inside the outer can 2 to create a reduced pressure. In this manner, one nozzle 11 is connected to a cell opening in the lid of the outer can 2, the air inside is removed, and the electrolyte solution EL is injected. The nozzle 11 is airtightly connected to the cell opening. This method has the advantage of reducing the number of openings in the secondary battery 1 because the pressure inside the secondary battery 1 is reduced through the same cell opening used for injecting the electrolyte solution EL. In the example of Figure 1, the liquid inlet 12 and the suction port 14 are shown side by side for the sake of explanation, but any known configuration can be used as appropriate, such as forming one in a circular shape and the other in an annular shape arranged around it. (Pump VP)

[0032] The pump VP is used to reduce the pressure inside the injection syringe 10 and the outer can 2. Operating the pump VP reduces the pressure inside the outer can 2 and the injection syringe 10 by suction. The pump VP is connected to the injection syringe 10 via a valve VV. In the example shown in FIG. 1 , the liquid reservoir chamber 13 and the suction path 15 of the injection syringe 10 are connected to the pump VP via separate paths. Each path is provided with a valve VV, allowing the liquid reservoir chamber 13 and the suction path 15 to be independently suctioned and set to different vacuum levels. While the example shown in FIG. 1 shows a configuration in which the liquid reservoir chamber 13 and the suction path 15 are depressurized by a common pump VP, the present disclosure is not limited to this configuration, and the liquid reservoir chamber and the suction path may each be connected to a separate pump. (Tank TK)

[0033] The tank TK stores the electrolyte EL to be injected into the outer can 2. The tank TK is connected to the liquid reservoir chamber 13 via a liquid supply pipe. If necessary, a liquid supply pump LP and a valve may be provided on the liquid supply pipe. (Volume variable mechanism 16)

[0034] The injection syringe 10 also includes a volume variable mechanism 16 on the suction path 15 that can change the volume of the suction path 15. The volume variable mechanism 16 may be formed, for example, in a piston or ring shape, with the piston portion airtightly slidable along the suction path 15, or any other known configuration may be used. The volume variable mechanism 16 can be operated to change the pressure inside the outer can 2. That is, when the volume of the suction path 15 is changed by the volume variable mechanism 16, the pressure inside the outer can 2 that is connected to the suction path 15 changes. Specifically, when the volume of the suction path 15 is increased by the volume variable mechanism 16, the pressure inside the suction path 15 decreases, and therefore the pressure inside the outer can 2 that is connected to the suction path 15 also decreases. This reduces the pressure inside the outer can 2 below the pressure inside the liquid reservoir chamber 13, making it easier for the electrolyte solution EL in the liquid reservoir chamber 13 to move to the interior of the outer can 2, where the pressure is lower. That is, injection can be performed smoothly.

[0035] In order to facilitate injection of the electrolyte solution EL into the exterior can 2, the pressure inside the exterior can 2 is reduced. When the internal pressure of the exterior can 2 is lower than the internal pressure of the injection syringe 10, the pressure difference makes it easier to guide the electrolyte solution EL into the interior of the exterior can 2.

[0036] Conventionally, in order to further reduce the pressure inside the outer can 2, which has already been reduced in pressure, it has been considered to use a booster pump. However, adding a booster pump complicates the piping, increases the equipment cost, and increases energy consumption. In addition, losses occur depending on the length of the piping required to add the booster pump.

[0037] In contrast, in the liquid injection device 100 according to this embodiment, the volume variable mechanism 16 is incorporated inside the liquid injection syringe 10, so no loss in piping occurs. Furthermore, the volume variable mechanism 16 can be realized with a simple configuration, such as a piston-like configuration, so additional costs can be kept low. Furthermore, the volume variable mechanism 16 may be provided at an eccentric position inside the liquid injection syringe 10, or may be arranged on the axis of the liquid injection syringe 10, for example, in a circular shape. [Embodiment 2]

[0038] The injection syringe 10 may also include a movable syringe shaft 17 extending therefrom. Such an example is shown in FIG. 2 as an injection device 200 according to a second embodiment. In this figure, the same components as those in the first embodiment and the like are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate. (Syringe shaft 17)

[0039] The syringe shaft 17 has a closing portion 18 at its tip that closes the path leading to the liquid inlet 12. The syringe shaft 17 is configured to be movable, allowing the closing portion 18 to open and close the path leading to the liquid inlet 12. In FIG. 2 , raising the syringe shaft 17 opens the closing portion 18, while lowering it closes the closing portion 18. In this way, the liquid inlet 12 can be closed by simply moving the syringe shaft 17, airtightly separating the liquid reservoir chamber 13 from the interior of the outer can 2 and allowing the pressure therein to be reduced individually. The closing portion 18 can be formed, for example, elastically, to liquid-tightly close the liquid inlet 12. Alternatively, a metal with a packing or sealing material can be used. Furthermore, the liquid inlet does not necessarily have to be closed at the tip of the syringe shaft; a portion such as the middle or shoulder portion can be used to close the liquid inlet. Note that closing the liquid inlet 12 with the closing portion 18 does not close the suction port 14. This allows the electrolyte solution EL held in the liquid reservoir chamber 13 to be retained while the air inside the outer can 2 is not impeded from being sucked in. (Syringe cup 19)

[0040] The injection syringe 10 has an open rear end of the liquid storage chamber 13. A syringe cup 19 is slidably inserted into the rear end of the injection syringe 10. This configuration makes it possible to vary the volume of the liquid storage chamber 13 using the syringe cup 19. The syringe cup 19 is configured to move independently of the volume variable mechanism 16. The syringe cup 19 and the volume variable mechanism 16 may be arranged coaxially. The operations of the syringe cup 19 and the volume variable mechanism 16 may be coordinated. For example, the volume variable mechanism 16 may be moved simultaneously when the syringe cup 19 is inserted, and after the syringe cup 19 is inserted, only the volume variable mechanism 16 may be moved while the syringe cup 19 is stationary. [Embodiment 3]

[0041] Furthermore, the present disclosure is not limited to a configuration in which the liquid reservoir chamber is closed by a sliding syringe cup to adjust the pressure, and it goes without saying that the liquid reservoir chamber may be closed by other members. For example, as in the liquid injection device 300 according to the third embodiment shown in Figure 3, a booster BS is provided on the liquid injection syringe to adjust the pressure in the liquid reservoir chamber.

[0042] In the above-described second and third embodiments, the syringe shaft is extended coaxially with the injection syringe, but the present disclosure is not limited to this configuration, and the syringe shaft may be disposed at an angle to the extension direction of the injection syringe or may intersect with the extension direction of the injection syringe.

[0043] A method for injecting the electrolyte solution EL into the outer can 2 of the electricity storage device will be described below. First, the nozzle 11 of the injection syringe 10 is inserted into the cell opening in the lid of the outer can 2. The nozzle 11 is airtightly connected to the cell opening. In this state, the injection port 12 of the nozzle 11 is closed, and the suction port 14 is open and communicates with the suction path 15. The suction path 15 is connected to the pump VP.

[0044] Next, the pump VP is operated to reduce the pressure inside the outer can 2 through the suction port 14 and the suction path 15. The degree of vacuum is set according to the volume of the outer can 2, the degree of filling inside, the viscosity of the electrolyte, etc., and is set to, for example, −90 kPa.

[0045] Meanwhile, the electrolyte solution EL is supplied from the tank TK connected to the injection syringe 10 into the liquid reservoir chamber 13 of the injection syringe 10. Because the injection port 12 is closed, the electrolyte solution EL is stored in the liquid reservoir chamber 13. Preferably, the electrolyte solution EL is supplied with the liquid reservoir chamber 13 open. This allows the electrolyte solution EL to be smoothly supplied to the liquid reservoir chamber 13 under atmospheric pressure. For example, injection is performed with the rear end of the injection syringe 10 open.

[0046] Then, with the liquid reservoir chamber 13 airtightly closed, the pump VP is used to depressurize the liquid reservoir chamber 13. To airtightly close the liquid reservoir chamber 13, for example, a syringe cup 19 is inserted into the rear end of the injection syringe 10 to close it. Because the liquid reservoir chamber 13 is separated from the interior of the outer can 2, the liquid reservoir chamber 13 is depressurized separately from the interior of the outer can 2. In other words, the liquid reservoir chamber 13 and the interior of the outer can 2 can be maintained at different pressures or atmospheric pressures.

[0047] In this state, the volume variable mechanism 16 provided on the suction path 15 is activated to expand the volume of the suction path 15, further reducing the pressure inside the outer can 2. Generally, the electrolyte solution EL can be injected into the outer can 2 by creating a pressure difference or air pressure difference between the liquid reservoir chamber 13 and the interior of the outer can 2. The greater the pressure difference, i.e., the higher the degree of vacuum inside the outer can 2 is compared to the degree of vacuum in the liquid reservoir chamber 13, the easier it is to inject the electrolyte solution EL. Therefore, it is important to increase the degree of vacuum inside the outer can 2. However, methods using a booster pump or the like complicate the configuration, incur significant losses due to piping length, and are energy inefficient. Therefore, in this embodiment, the volume variable mechanism 16 provided on the suction path 15 in the injection syringe 10 is activated to expand the volume of the suction path 15, thereby further reducing the pressure inside the outer can 2, which is connected to the suction path 15 via the suction port 14. The electrolyte solution EL in the liquid reservoir chamber 13 is then injected into the outer can 2. This enables the electrolyte solution EL to be efficiently injected into the outer can 2. In particular, the volume variable mechanism 16 incorporated into the injection syringe 10 has a simple configuration that allows additional pressure reduction and efficiently increases the degree of vacuum. Furthermore, by expanding only the volume of the suction path 15 with the volume variable mechanism 16 while maintaining the liquid reservoir chamber 13 at a constant volume, it is possible to easily reduce only the pressure on one side and generate a pressure difference.

[0048] After the electrolyte solution EL in the liquid reservoir chamber 13 is injected into the outer can 2, the liquid reservoir chamber 13 is connected to the interior of the outer can 2, so the volume of the liquid reservoir chamber 13 can be reduced to pressurize the interior of the outer can 2. This allows a certain amount of pressure to be applied and preliminary liquid injection to be performed. Finally, the liquid reservoir chamber 13 and the suction path 15 are opened to atmospheric pressure.

[0049] In this way, the electrolyte solution EL can be smoothly injected into the exterior can 2. Furthermore, the speed at which the electrolyte solution EL permeates the electrode body can be increased, thereby improving the impregnation efficiency.

[0050] The liquid injection device and liquid injection method according to the present disclosure can be applied to the injection of liquid into battery cells such as lithium ion secondary batteries, as well as into electricity storage devices such as capacitors, and can also be applied to the injection of liquids other than electrolytes.

[0051] Furthermore, the liquid injection device and liquid injection method according to the present disclosure can reduce the energy required to create a vacuum or reduced-pressure state in the electricity storage device, thereby reducing power consumption and, as a result, reducing the consumption of fossil fuels required for power generation and reducing the environmental impact. As a result, this technology contributes to the achievement of the following of the 17 goals and 169 targets set out in the Sustainable Development Goals (SDGs), international goals adopted at the United Nations Summit in September 2015: - "8. Decent work and economic growth", "8.4 By 2030, improve progressively resource efficiency in global consumption and production and endeavour to decouple economic growth from environmental degradation, in accordance with the 10-year framework of programmes on sustainable consumption and production, with developed countries taking the lead", "9. Industry, innovation and infrastructure", and "9.4 By 2030, enhance sustainability through infrastructure and industry improvement through improved resource efficiency and the expanded introduction of clean technologies and environmentally friendly technologies and industrial processes, with all countries taking action in accordance with their respective capabilities".

[0052] 100, 200, 300... Liquid injection device 1... Secondary battery 2... Outer can 10... Liquid injection syringe 11... Nozzle portion 12... Liquid injection port 13... Liquid reservoir chamber 14... Suction port 15... Suction path 16... Volume variable mechanism 17... Syringe shaft 18... Closure portion 19... Syringe cup EL... Electrolyte VP... Pump TK... Tank VV... Valve LP... Liquid supply pump BS... Booster

Claims

1. A method for injecting an electrolyte into an outer can of an electricity storage device, comprising the steps of: inserting a nozzle portion of an injection syringe, the nozzle portion having an injection port for supplying the electrolyte into the inside of the outer can and an suction port connected to a suction path connected to an external pump for depressurizing the outer can, into a cell opening opened in the outer can; reducing the pressure inside the outer can through the suction port and the suction path; supplying the electrolyte to a liquid reservoir chamber airtightly separated from the suction path within the injection syringe; reducing the pressure of the liquid reservoir chamber separately from the inside of the outer can; operating a volume variable mechanism provided on the suction path within the injection syringe to expand the volume of the suction path, thereby further reducing the pressure inside the outer can which is connected to the suction path via the suction port; and injecting the electrolyte in the liquid reservoir chamber into the outer can.

2. The liquid injection method according to claim 1, further comprising the step of air-tightly closing the liquid injection port so that the liquid reservoir chamber does not communicate with the inside of the outer can prior to the step of reducing the pressure inside the outer can.

3. A liquid injection method as claimed in claim 2, wherein the step of airtightly closing the liquid injection port comprises moving a syringe shaft extended within the liquid injection syringe to close the path leading to the liquid injection port with the tip of the syringe shaft.

4. A liquid injection method according to claim 1, wherein the step of supplying the electrolyte to the liquid reservoir chamber is carried out with the liquid reservoir chamber open.

5. A liquid injection method according to claim 4, wherein the step of supplying the electrolyte to the liquid reservoir chamber is carried out with the rear end of the liquid injection syringe being opened to the liquid reservoir chamber.

6. A liquid injection method according to claim 5, wherein the step of reducing the pressure in the liquid reservoir chamber is carried out in a state in which the liquid injection syringe is closed by a syringe cup inserted from the rear end of the liquid injection syringe.

7. A liquid injection method as claimed in claim 6, wherein the step of further reducing the pressure inside the outer can is carried out by expanding the volume of the suction path with the volume variable mechanism while maintaining the volume of the liquid storage chamber at a constant level with the syringe cup.

8. A liquid injection method according to any one of claims 1 to 7, further comprising the step of reducing the volume of the liquid reservoir chamber of the injection syringe to pressurize the inside of the outer can following the step of injecting the electrolyte in the liquid reservoir chamber into the outer can.

9. The liquid injection method according to claim 8, further comprising the step of releasing the liquid reservoir chamber and the suction path to atmospheric pressure following the step of pressurizing the inside of the outer can.

10. The liquid injection method according to any one of claims 1 to 7, wherein the power storage device is a lithium ion secondary battery.

11. An injection device for injecting an electrolyte into an outer can of an electrical storage device, comprising: an injection syringe including a nozzle portion which defines a liquid reservoir chamber and a suction path therein, the injection syringe including a nozzle portion which is connected to the liquid reservoir chamber and has an injection port for supplying the electrolyte into the inside of the outer can and a suction port which is connected to the suction path at one end; a pump which is connected to the suction path at the other end and which reduces the pressure in the outer can; and a tank which is connected to the liquid reservoir chamber and stores the electrolyte, the injection device comprising: an injection syringe having a volume variable mechanism provided on the suction path.

12. A liquid injection device as described in claim 11, wherein the liquid injection syringe has a movable syringe shaft extending therefrom, and the syringe shaft has a closing portion at its tip for closing the path leading to the liquid injection port, and the liquid injection device is configured such that the path leading to the liquid injection port can be opened and closed at the closing portion by moving the syringe shaft.

13. A liquid injection device according to claim 11, wherein the liquid injection syringe has an open rear end of the liquid storage chamber, and a syringe cup is slidably inserted into the rear end of the liquid injection syringe.

14. The liquid injection device according to any one of claims 11 to 13, wherein the power storage device is a lithium ion secondary battery.

15. An injection syringe for use in an injection device that injects electrolyte into the outer can of an electricity storage device, the injection syringe defining an internal liquid storage chamber and a suction path, the injection syringe comprising a nozzle portion that is connected to the liquid storage chamber and has an injection port for supplying the electrolyte into the inside of the outer can, and a suction port that is connected at one end to the suction path, and a volume variable mechanism is provided on the suction path.

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