All-solid-state battery pressurization system

Abstract

The present invention relates to a solid-state battery pressurization system comprising a jig for pressurizing a solid-state battery from above and below, and a hydraulic press for applying uniform pressure to the jig, wherein a constant pressure is applied to the jig by the pressure applied from the hydraulic press.

Description

[Technical Field]

[0001] This application claims priority rights under Korean Patent Application No. 10-2023-0164806 dated November 23, 2023, and Korean Patent Application No. 10-2024-0167560 dated November 21, 2024, and all content disclosed in the documents of said Korean Patent Applications is incorporated herein by reference.

[0002] This invention relates to an all-solid-state battery pressurization system. [Background technology]

[0003] A secondary battery is a device that stores external electrical energy in the form of chemical energy and generates electricity when needed. Because it can be recharged many times, it is also called a rechargeable battery. Commonly used secondary batteries include lead-acid batteries, nickel-cadmium batteries (NiCd), nickel-metal hydride batteries (NiMH), and lithium-ion batteries. Secondary batteries offer both economic and environmental advantages compared to primary batteries, which are used once and then discarded.

[0004] Meanwhile, as wireless communication technology continues to develop, there is a growing demand for lighter, thinner, and smaller portable devices and automotive accessories, and for rechargeable batteries used as energy sources for these devices. In particular, with the practical application of hybrid and electric vehicles, and from the perspective of preventing environmental pollution, research into using rechargeable batteries in these next-generation automotive batteries to reduce manufacturing costs and weight and extend lifespan is attracting attention. Among the various types of rechargeable batteries, lithium-ion batteries, which are lightweight, exhibit high energy density and operating potential, and have a long cycle life, have recently been gaining prominence.

[0005] Generally, lithium secondary batteries are manufactured by mounting an electrode stack, consisting of a negative electrode, a positive electrode, and a separator membrane, inside a cylindrical or rectangular metal can or an aluminum laminate sheet pouch-type case, and then injecting an electrolyte into the electrode stack.

[0006] Conventionally, electrolytes for lithium secondary batteries have mainly been liquid electrolytes in which lithium salts are dissolved in non-aqueous organic solvents. However, such liquid electrolytes have a high probability of electrode material degeneration and organic solvent volatilization, as well as the risk of combustion or explosion due to rising ambient and battery temperatures, and leakage, making it difficult to realize lithium secondary batteries of various types with high safety.

[0007] On the other hand, all-solid-state batteries, which utilize solid electrolytes, have the advantage of being able to fabricate electrode stacks safely and simply because they eliminate organic solvents.

[0008] Solid-state batteries are classified into oxide-based, polymer-based, and sulfide-based types based on the raw materials of their solid electrolyte. Sulfide-based solid-state batteries are attracting attention because they have superior lithium-ion conductivity compared to other types of batteries. However, despite their excellent properties, they have the disadvantage of higher ionic conductivity and electrical resistance between the positive and negative electrodes compared to liquid batteries, resulting in inferior lifespan and output compared to existing batteries that utilize liquid electrolytes.

[0009] On the other hand, secondary batteries are manufactured through a process of assembling cells and a process of activating the batteries. In the battery activation stage, battery cells are mounted in a charging / discharging device such as a jig, and charging and discharging are performed under the conditions necessary for activation. This process of using a jig to perform predetermined charging and discharging for battery activation is called the formation process.

[0010] Solid-state batteries are also rechargeable batteries and therefore undergo charging and discharging processes, which require applying pressure to the cells through a jig or similar device. Currently, the method used to pressurize the cells involves tightening the jig screws one by one using a torque wrench, but this method has the problem of not being able to apply uniform pressure to the cells. Furthermore, the larger the cell area, the greater the pressure that must be applied, but there are limitations to using only screw tightening without a press device.

[0011] Therefore, in order to solve the aforementioned problems, research is needed on pressurization systems for all-solid-state batteries that apply uniform pressure to the entire surface area of ​​the cell. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] U.S. Published Patent No. 2023-0028855 [Overview of the project] [Problems that the invention aims to solve]

[0013] The present invention aims to provide a pressurization system for all-solid-state batteries in which uniform pressure is applied to the entire surface area of ​​the cell during charging and discharging of the all-solid-state battery. [Means for solving the problem]

[0014] In order to achieve the aforementioned objective, The present invention provides a solid-state battery pressurization system comprising a jig for pressurizing a solid-state battery from above and below, and a hydraulic press for applying uniform pressure to the jig, wherein a constant pressure is applied to the jig by the pressure applied from the hydraulic press.

[0015] In one embodiment of the present invention, the all-solid-state battery pressurization system includes a plurality of jigs, each of which has a different surface area in contact with the all-solid-state battery.

[0016] In one embodiment of the present invention, each of the multiple jigs may be pressurized by a plurality of hydraulic presses, and the plurality of hydraulic presses may be connected from a single hydraulic cylinder via a plurality of hydraulic connecting pipes.

[0017] In one embodiment of the present invention, the plurality of jigs includes a first jig and a second jig, and the area of ​​the first jig is 6,000 mm². 2 The following applies, and the area of ​​the second jig is 6,000 mm². 2 It may exceed that.

[0018] In one embodiment of the present invention, the first jig may adjust the pressure in units of 0.5 bar to 3 bar, and the second jig may adjust the pressure in units of more than 3 bar to 8 bar.

[0019] In one embodiment of the present invention, when a certain pressure is applied to the jig by the pressure applied from the hydraulic press and the thickness of the all-solid-state battery decreases, the screw of the jig may be tightened to maintain the pressure.

[0020] In one embodiment of the present invention, after tightening the screw of the jig to maintain the pressure applied to the all-solid-state battery, the pressure applied from the hydraulic press may be removed.

[0021] [[ID=十四年]] In one embodiment of the present invention, after tightening the screw of the jig to maintain the pressure applied to the all-solid-state battery, the pressure applied from the hydraulic press may be removed.

[0022] In one embodiment of the present invention, the all-solid-state battery may be a sulfide-based all-solid-state battery.

Effects of the Invention

[0023] The pressure application system for the all-solid-state battery of the present invention can apply a uniform pressure to the cell even when the area of the cell increases, improve the charge / discharge efficiency of the cell, improve the rate performance of the cell, and improve the charge / discharge cycle of the cell.

Brief Description of the Drawings

[0024] [Figure 1] It is a photograph showing a pressure application system for an all-solid-state battery according to a conventional invention. [Figure 2] It is a schematic diagram showing a pressure application system for an all-solid-state battery according to an embodiment of the present invention. [Figure 3] It is a schematic diagram showing a pressure application system for an all-solid-state battery according to an embodiment of the present invention. [Figure 4]This is a schematic diagram showing a pouch manufactured for pressurizing an all-solid-state battery according to one embodiment of the present invention. [Figure 5] This is a photograph showing the results of a solid-state battery pressurized by a solid-state battery pressurization system according to one embodiment of the present invention. [Modes for carrying out the invention]

[0025] The present invention will be described in detail below, based on the attached drawings, so that it can be easily implemented by a person with ordinary skill in the art to which the invention pertains. However, the present invention can be implemented in various different forms and is not limited to the embodiments described herein.

[0026] To clearly explain the present invention, irrelevant parts have been omitted, and the same or similar reference numerals have been used throughout the specification for identical or similar components.

[0027] Furthermore, the terms and words used in this specification and in the claims shall not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical concept of the present invention, based on the principle that inventors may define the concepts of terms as appropriate to best describe their invention.

[0028] The embodiments will be described in detail below with reference to the attached drawings. However, the present invention can be carried out in various different forms and is not limited to the embodiments described herein.

[0029] Among conventional all-solid-state batteries, those using sulfide-based solid electrolytes undergo a charging and discharging process, during which pressure must be applied to the cells via a jig or similar device. Conventionally, as shown in Figure 1, a method was used to pressurize the cells by tightening the jig screws one by one using a torque wrench. However, this method was not only cumbersome but also had the problem of not being able to apply uniform pressure to the cells. Furthermore, as the cell area increases, greater pressure is required, but there were limitations to the method of tightening screws without a press device.

[0030] Therefore, in order to solve the aforementioned problems, research is needed on pressurization systems for all-solid-state batteries that apply uniform pressure to the entire surface area of ​​the cell.

[0031] Therefore, the inventors have developed a method to ensure that uniform pressure is applied to the entire surface area of ​​the all-solid-state battery cell. We have found that the aforementioned problem can be solved through an all-solid-state battery pressurization system that includes a jig for pressurizing an all-solid-state battery from above and below, and a hydraulic press for applying uniform pressure to the jig, wherein a constant pressure is applied to the jig by the pressure applied from the hydraulic press, and have thus completed the present invention.

[0032] This invention relates to an all-solid-state battery pressurization system. Specifically, it includes a jig for applying pressure to the all-solid-state battery from above and below, and a hydraulic press for applying uniform pressure to the jig.

[0033] In the all-solid-state battery pressurization system of the present invention, a constant pressure is applied to the jig by the pressure applied from the hydraulic press, thereby applying a constant pressure to the top and bottom of the all-solid-state battery.

[0034] As shown in Figure 2, the all-solid-state battery pressurization system of the present invention includes a plurality of jigs, each of which may have a different surface area in contact with the all-solid-state battery. By using a plurality of jigs with different surfaces, the all-solid-state battery pressurization system of the present invention may apply different pressures to each jig.

[0035] In the all-solid-state battery pressurization system of the present invention, a constant pressure is applied to the jig by the pressure applied from the hydraulic press, and as the thickness of the all-solid-state battery decreases, the screws on the jig can be tightened to maintain the pressure. When the hydraulic press applies pressure to the jig, the screws on the jig loosen, and by tightening the screws by the amount they loosened, the pressure applied by the hydraulic press can be maintained.

[0036] The all-solid-state battery pressurization system of the present invention allows for the removal of pressure applied from the hydraulic press after maintaining the pressure applied to the all-solid-state battery by tightening the screws of the jig. As mentioned above, tightening the screws maintains the pressure applied by the hydraulic press, but in this case, even if the pressure applied by the hydraulic press is removed, the pressure applied to the all-solid-state battery by the jig can be maintained.

[0037] In the present invention, each of the multiple jigs is pressurized by a plurality of hydraulic presses, and as shown in Figure 3, the plurality of hydraulic presses can be connected from a single hydraulic cylinder (30) via a plurality of hydraulic connecting pipes (31, 32). One hydraulic press (21, 22) is placed for each of the jigs (11, 12), and when this hydraulic press (21, 22) applies pressure to one side of the jig (11, 12), pressure is also applied to the all-solid-state battery. The means by which pressure is applied to such hydraulic presses (21, 22) is the hydraulic cylinder (30). In the present invention, the hydraulic cylinder (30) applies pressure to the plurality of hydraulic presses (21, 22) through a plurality of hydraulic connecting pipes (31, 32), but since a plurality of hydraulic connecting pipes (31, 32) are connected to one hydraulic press (21, 22), the hydraulic cylinder (30) is connected to a plurality of hydraulic presses (21, 22), and thereby pressure is applied to the plurality of jigs (11, 12).

[0038] In this invention, although there is only one hydraulic cylinder (30), the pressure applied to it can be changed by adjusting the area of ​​the jigs (11,12) connected to it to be different. Each time a single hydraulic cylinder (30) pumps, the cylinder moves by a certain distance, which is defined as the feed distance. Thus, there is a constant feed distance per pump, and as a result, an additional pressure of a certain value may be applied. This feed distance varies depending on the pressure of the cylinder, but for example, if the area of ​​the cylinder is 71.15 cm² 2 In this case, the cylinder feed distance per pump is 0.13 mm. In this case, the pressure applied to a jig with an outer width of 7 cm x 7 cm will increase by 1 bar per pump. Similarly, if the cylinder area is 33.2 cm² 2 In this case, the cylinder feed distance per pump is 1.1 mm (for pressures of 13 bar or less) or 0.28 mm (for pressures of 13 bar or more), and in this case, the pressure applied to a jig with an outer diameter of 8 cm x 10 cm increases by 5 bar per pump.

[0039] In this way, the pressure applied to the jig can be changed by changing the area (outer width) of the jig. Therefore, in the present invention, when the plurality of jigs include a first jig and a second jig, the area of ​​the first jig is 6,000 mm². 2 The following applies, and the area of ​​the second jig is 6,000 mm². 2 It can be set to be greater than or equal to.

[0040] In this case, the first jig in the all-solid-state battery pressurization system of the present invention can adjust the pressure in increments of 0.5 bar to 3 bar, and the second jig can adjust the pressure in increments of more than 3 bar to 8 bar.

[0041] The pressure can be adjusted using a gauge (40), a manual valve (50), a manual pump (60), etc., and the gauge, valve, and pump may be those commonly used in the industry.

[0042] In the present invention, the all-solid-state battery pressurized by the all-solid-state battery pressurization system may include a positive electrode, a negative electrode, and a solid electrolyte. It may also further include a positive electrode lead and a negative electrode lead connected to the positive electrode and the negative electrode, respectively.

[0043] All-solid-state batteries may have a positive electrode, a negative electrode, and a solid electrolyte housed in a pouch, or they may be pouch-type battery cells in which a portion of the positive electrode leads and negative electrode leads are exposed to the outside of the pouch. Pouch-type battery cells can be manufactured by placing a solid electrolyte between the positive and negative electrodes, pressurizing and interbonding them, and then attaching the positive and negative electrode leads to form an electrode assembly which is then housed in a pouch and sealed.

[0044] However, the structure of the all-solid-state battery pressurized by the all-solid-state battery pressurization system according to one embodiment of the present invention is not limited thereto.

[0045] The configuration of the positive electrode, negative electrode, solid electrolyte layer, positive electrode lead, negative electrode lead, and pouch included in the all-solid-state battery may be used without particular limitations as long as they are used in all-solid-state batteries used in the industry, but a sulfide-based all-solid-state battery is preferred.

[0046] In the present invention, the all-solid-state battery may be a sulfide-based all-solid-state battery. Therefore, the positive electrode, negative electrode, and solid electrolyte layer included in the all-solid-state battery of the present invention may contain a sulfide-based solid electrolyte.

[0047] The sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and may include Li-PS glass or Li-PS glass ceramics. Non-limiting examples of such sulfide-based solid electrolytes include Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, Li2S-GeS2-ZnS, and may contain one or more of these. However, it is not limited to these.

[0048] The solid electrolyte layer of the present invention may be manufactured using the sulfide-based solid electrolyte. The method for forming the solid electrolyte layer is not particularly limited as long as it is used in the industry. For example, the solid electrolyte layer may be manufactured by mixing solid electrolyte powder, a binder, and a solvent to produce a slurry containing the sulfide-based solid electrolyte, then applying the slurry to a current collector on which electrodes are formed, and then drying and rolling it. The binder and solvent may be used without particular limitation as long as they are materials that do not react with sulfur in the solid electrolyte.

[0049] A positive electrode according to one embodiment of the present invention may include a positive electrode current collector, a positive electrode active material, and a solid electrolyte.

[0050] The positive electrode current collector is for supporting the positive electrode active material, and is not particularly limited as long as it has excellent conductivity and is electrochemically stable in the voltage range of the lithium secondary battery. For example, the positive electrode current collector may be any one metal selected from the group consisting of copper, aluminum, stainless steel, titanium, silver, palladium, nickel, alloys thereof, and combinations thereof. The stainless steel may be surface-treated with carbon, nickel, titanium, or silver. As the alloy, an aluminum-cadmium alloy may be preferably used. In addition, fired carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer may be used.

[0051] The positive electrode current collector may form fine irregularities on its surface to strengthen the bonding force with the positive electrode active material, and various forms such as a film, sheet, foil, mesh, net, porous, foam, non-woven fabric, etc. may be used.

[0052] The solid electrolyte contained in the positive electrode of the present invention is the same as the content of the solid electrolyte described above.

[0053] The positive electrode active material may optionally contain a conductive material and a binder in addition to the positive electrode active material.

[0054] The positive electrode active material may vary depending on the type of all-solid-state battery. For example, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), a compound substituted with one or more transition metals; the chemical formula Li 1+x Mn 2-x O4 (0 < x ≦ 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; the chemical formula LiNi 1-x M x O2 (M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga; 0.01 ≦ x ≦ 0.3) Ni-site type lithium nickel oxide represented by; the chemical formula LiMn 2-x M xLithium manganese composite oxide represented as O2 (M=Co, Ni, Fe, Cr, Zn, or Ta; 0.01≦x≦0.1) or Li2Mn3MO8 (M=Fe, Co, Ni, Cu, or Zn); LiNi x Mn 2-x Lithium manganese composite oxide with a spinel structure represented by O4; LiCoPO4; LiFePO4; elemental sulfur (S8); Li2S n (n=1), organosulfur compounds or carbon-sulfur polymers ((C2S x ) n It may contain sulfur-based compounds such as (x=2.5~50, n=2), but is not limited to these.

[0055] The conductive material is a substance that electrically connects the electrolyte and the positive electrode active material, acting as a pathway for electrons to move from the current collector to the positive electrode active material. It can be used without limitation as long as it does not undergo chemical changes in a lithium secondary battery and is porous and conductive.

[0056] For example, the conductive material may be a porous carbon-based material, such as carbon black, graphite, graphene, activated carbon, carbon fiber, metallic fibers such as metal mesh; metallic powders such as copper, silver, nickel, and aluminum; or organic conductive materials such as polyphenylene derivatives. The conductive materials may be used individually or in combination.

[0057] Currently, commercially available conductive materials include acetylene black (such as products from Chevron Chemical Company or Gulf Oil Company), Ketjen Black EC (products from Armak Company), Vulcan XC-72 (products from Cabot Company), and Super P (products from MMM). Examples include acetylene black, carbon black, and graphite.

[0058] Furthermore, the positive electrode may further contain a binder, the binder which enhances the bonding force between the components constituting the positive electrode and between them and the current collector, and any binder known in the industry may be used.

[0059] For example, the binder may be one, a mixture of two or more, or a copolymer selected from the group consisting of: fluororesin binders containing polyvinylidenefluoride (PVdF) or polytetrafluoroethylene (PTFE); rubber binders containing styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; cellulose binders containing carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; polyalcohol binders; polyolefin binders containing polyethylene or polypropylene; polyimide binders; polyester binders; and silane binders.

[0060] An embodiment of the present invention may include a negative electrode current collector, a negative electrode active material, and a solid electrolyte.

[0061] The negative electrode, like the positive electrode, may optionally contain a conductive material and a binder. In this case, the negative electrode current collector, conductive material, and binder may be those commonly used in negative electrodes, as described above.

[0062] The negative electrode active material according to one embodiment of the present invention may be a lithium metal, a lithium alloy, or a negative electrode-free form.

[0063] The aforementioned negative electrode-free configuration may include only a negative electrode current collector, or a structure in which a carbon layer containing a binder is coated on the negative electrode current collector.

[0064] Those with ordinary skill in the art related to this embodiment will understand that it can be realized in modified forms without departing from the essential characteristics described above. Therefore, the disclosed method should be considered in an explanatory rather than restrictive view. The scope of the invention is shown in the claims and not in the foregoing description, and all differences within an equivalent scope should be construed as being included in the invention.

[0065] The following are preferred embodiments to aid in understanding the present invention, but these embodiments are provided to make the present invention easier to understand and the invention is not limited thereto.

[0066] Examples After fabricating a cell containing pressure-sensitive paper as shown in Figure 4, a test was conducted in which pressure was applied using a hydraulic press as described in the present invention.

[0067] The results are shown in Figure 5, confirming that using a hand hydraulic press allows for pressurization close to the desired pressure and that the pressure is applied uniformly throughout the entire cell.

[0068] Specifically, as shown in Figure 2, the hand hydraulic press comprises two jigs (a first jig and a second jig) and cylinders connected to each jig. First, the area of ​​the cylinder connected to the first jig is 71.15 cm². 2 The cylinder feed distance per pump is 0.13 mm, and the area is 7 cm * 7 cm (4,900 mm). 2 The pressure applied to the first jig, which has an area of ​​), increased by 1 bar per pump. Similarly, the area of ​​the cylinder connected to the second jig was 33.2 cm². 2 The cylinder feed distance per pump is 1.1 mm, and the volume is 8 cm * 10 cm (8,000 mm). 2 The pressure applied to the second jig, which has the outer width of ), increased by 5 bar per pump.

[0069] In this all-solid-state battery pressurization system, the multiple hydraulic presses are connected to a single hydraulic cylinder via multiple hydraulic connecting pipes, and by adjusting only one hydraulic cylinder, multiple hydraulic presses that apply different pressures can be activated.

[0070] Subsequently, after pressurizing the all-solid-state battery, it was confirmed that the same pressure was applied in the thickness direction of the cell through the pressure-sensitive paper on the top, middle, and bottom surfaces, and this is shown in Figure 5.

[0071] This revealed that the all-solid-state battery pressurization system of the present invention can apply uniform pressure to cells even when the cell area is large, thereby improving the charge and discharge efficiency of the cells, enhancing the rate performance of the cells, and improving the charge and discharge cycle of the cells. [Explanation of Symbols]

[0072] 11: Jig 12: Jig 21: Hydraulic press 22: Hydraulic press 30: Hydraulic cylinder 31: Hydraulic connection pipe 32: Hydraulic connection pipe 40: Gauge 50: Manual valve 60: Manual pump

Claims

1. A jig for applying pressure to an all-solid-state battery from above and below; and A hydraulic press that applies uniform pressure to the jig; A solid-state battery pressurization system in which a constant pressure is applied to a jig by the pressure applied from the aforementioned hydraulic press.

2. The aforementioned jigs include multiple units, The solid-state battery pressurization system according to claim 1, wherein the plurality of jigs each have a different surface area in contact with the solid-state battery.

3. The all-solid-state battery pressurization system according to claim 2, wherein each of the plurality of jigs is pressurized by a plurality of hydraulic presses, and the plurality of hydraulic presses are connected from a single hydraulic cylinder via a plurality of hydraulic connecting pipes.

4. The aforementioned plurality of jigs include a first jig and a second jig, The area of ​​the first jig is 6,000 mm². ２ The following: The area of ​​the second jig is 6,000 mm². ２ The all-solid-state battery pressurization system according to claim 3, which is superior.

5. The first jig adjusts the pressure in increments of 0.5 bar to 3 bar, The all-solid-state battery pressurization system according to claim 4, wherein the second jig adjusts the pressure in increments of more than 3 bar to 8 bar.

6. When a constant pressure is applied to the jig by the pressure from the hydraulic press, the thickness of the solid-state battery decreases. The all-solid-state battery pressurization system according to claim 1, wherein pressure is maintained by tightening the screws of the jig.

7. After tightening the screws of the jig to maintain the pressure applied to the solid-state battery, The all-solid-state battery pressurization system according to claim 6, which removes the pressure applied from a hydraulic press.

8. The all-solid-state battery pressurization system according to claim 1, wherein the all-solid-state battery is a sulfide-based all-solid-state battery.

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