Battery cell pressure pad and battery cell pressure device including the same

Abstract

The present invention relates to a battery cell pressure pad and a battery cell pressure device including the same, and more particularly to a battery cell pressure pad for improving the performance of an all-solid-state battery cell.

Description

[Technical Field]

[0001] The present invention relates to a battery cell pressure pad and a battery cell pressure device including the same, and more particularly to a battery cell pressure pad for improving the performance of an all-solid-state battery cell.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0146536, filed October 30, 2023, and Korean Patent Application No. 10-2024-0134545, filed October 4, 2024, and incorporates all contents disclosed in the documents of said Korean patent applications as part of this specification. [Background technology]

[0003] As technological development and demand for mobile devices increases, rechargeable secondary batteries are widely used as energy sources for various mobile devices. Secondary batteries are also attracting attention as energy sources for electric vehicles and hybrid vehicles, which have been proposed as a solution to air pollution caused by conventional gasoline and diesel vehicles.

[0004] Secondary batteries are classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries depending on the shape of the battery case. Among these, pouch-type batteries are shaped using a pouch exterior material made of a metal layer (foil) and a multilayered film of synthetic resin layers coated on the top and bottom of the metal layer, which significantly reduces the weight of the battery compared to cylindrical or prismatic types that use metal cans. They are attracting much attention for their advantages of being lightweight and adaptable to various shapes.

[0005] Pouch-type batteries are generally manufactured through a battery assembly process followed by a battery cell activation process, which generally involves pressing the battery cells with a jig and applying a current to the battery cells up to a predetermined voltage to charge and discharge them.

[0006] In the cell assembly process for manufacturing a pouch-type battery, it is important to apply uniform pressure to the battery cell. In particular, in the process for manufacturing an all-solid-state battery, it is important to properly form contact interfaces between the positive and negative electrodes and the solid electrolyte.

[0007] However, in order to improve contact between the positive and negative electrodes and the solid electrolyte, charging or discharging is performed while applying clamping pressure to the battery cell. At this time, uneven pressure is applied to parts of the battery cell, which reduces the cell life performance and affects the initial charge / discharge efficiency.

[0008] Therefore, it is necessary to develop a pressure pad that can provide excellent initial charge / discharge efficiency and performance of the all-solid-state battery and ensure that the charge / discharge cycle is performed smoothly. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 6912658 Summary of the Invention [Problem to be solved by the invention]

[0010] One object of the present invention is to provide a battery cell pressure pad that allows uniform pressure to be applied when fastening a battery cell to a jig in the manufacture of an all-solid-state battery.

[0011] Another object of the present invention is to provide a battery cell pressure pad that enables the production of a battery with excellent initial charge / discharge efficiency and improved performance.

[0012] Another object of the present invention is to provide a battery cell pressure pad that improves the charge-discharge cycle performance of an all-solid-state battery. [Means for solving the problem]

[0013] As one embodiment of the present invention, there is provided a battery cell pressure pad for applying pressure to a battery cell having electrodes and a solid electrolyte stacked thereon, the battery cell pressure pad including a first pressure pad that contacts one side of the battery cell and applies pressure to the one side of the battery cell, and a second pressure pad that is stacked on the first pressure pad and contacts one side of a pressure jig.

[0014] In one embodiment of the present invention, the first pressure pad is a battery cell pressure pad that presses both sides of the battery cell with the battery cell therebetween, and includes a 1-1 pressure pad that presses one side of the battery cell and a 1-2 pressure pad that presses the other side of the battery cell.

[0015] In one embodiment of the present invention, the second pressure pad includes a 2-1 pressure pad stacked on the 1-1 pressure pad and a 2-2 pressure pad stacked on the 1-2 pressure pad, and the 2-1 pressure pad and the 2-2 pressure pad provide battery cell pressure pads that respectively contact one side of a pressure jig facing each other.

[0016] In one embodiment of the present invention, the first and second pressure pads each have a CFD (Compression Force Deflection) 60% value of 4,000 kPa or more.

[0017] In one embodiment of the present invention, there is provided a battery cell pressure pad in which the CFD 60% value of the first pressure pad is greater than the CFD 60% value of the second pressure pad.

[0018] In one embodiment of the present invention, a battery cell pressure pad is provided in which the CFD 60% value of the first pressure pad is 7,000 kPa or more.

[0019] In one embodiment of the present invention, the thickness (T c The thickness ratio of the first pressure pad (T1) to the thickness of the first pressure pad (T2) is 1:0.01 to 0.5.

[0020] In one embodiment of the present invention, a battery cell pressure pad is provided, the thickness of the first pressure pad satisfying the following formula 1: [Formula 1] T1>T p -T u In the formula 1, T p is the thickness of the positive electrode in the battery cell, T u is the thickness of the pouch film inside the battery cell.

[0021] In one embodiment of the present invention, there is provided a battery cell pressure pad in which the thickness of the first pressure pad is reduced by 60% or more based on the initial thickness when the first pressure pad is compressed multiple times at a deformation rate of 80% based on the initial thickness.

[0022] In one embodiment of the present invention, there is provided a battery cell pressure pad in which the CFD 50% values ​​of the first pressure pad and the second pressure pad are 2,000 kPa or more.

[0023] In one embodiment of the present invention, there is provided a battery cell pressure pad in which the CFD50% value of the first pressure pad is greater than the CFD50% value of the second pressure pad.

[0024] In one embodiment of the present invention, a battery cell pressure pad is provided in which the CFD (Compression Force Deflection) 50% value of the first pressure pad is 3,000 kPa or more.

[0025] In one embodiment of the present invention, a battery cell pressing device including the battery cell pressing pad is provided.

[0026] In one embodiment of the present invention, a battery cell pressing device is provided in which a battery cell is disposed between the battery cell pressing pads.

[0027] As one embodiment of the present invention, there is provided a battery cell pressing device that applies uniaxial or isotropic pressure to the battery cell. [Effects of the Invention]

[0028] The battery cell pressure pad according to the present invention can apply uniform pressure when fastening the battery cell to the jig.

[0029] The battery cell pressure pad according to the present invention makes it possible to manufacture an all-solid-state battery with excellent initial charge / discharge efficiency and improved performance.

[0030] The battery cell pressure pad according to the present invention can improve the charge-discharge cycle performance of an all-solid-state battery. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a schematic diagram showing a battery cell pressure pad according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram showing a battery cell pressure pad according to an embodiment of the present invention; [Figure 3] FIG. 1 is a diagram showing the charge / discharge rates of battery cells pressed using battery cell pressure pads according to Example 1 of the present invention and Comparative Examples 1 and 2. [Figure 4] FIG. 1 is a graph showing the cycle retention rates of battery cells pressed using battery cell pressure pads according to Example 1 of the present invention and Comparative Examples 1 and 2. [Figure 5] FIG. 10 is a diagram showing the charge / discharge rates of battery cells pressed using battery cell pressure pads according to Example 1 of the present invention and Comparative Examples 3 and 4. [Figure 6] FIG. 10 is a graph showing the cycle retention rates of battery cells pressed using battery cell pressure pads according to Example 1 of the present invention and Comparative Examples 3 and 4. [Figure 7] FIG. 10 is a diagram showing the charge / discharge rates of battery cells pressed using battery cell pressure pads according to Example 1 of the present invention and Comparative Example 5. [Figure 8] FIG. 10 is a graph showing the cycle retention rates of battery cells pressed using battery cell pressure pads according to Example 1 of the present invention and Comparative Example 5. [Figure 9] FIG. 10 is a diagram showing a compression curve of a pressure pad according to Comparative Example 6 of the present invention. [Figure 10]FIG. 10 is a diagram showing the charge / discharge rates of battery cells pressed using battery cell pressure pads according to Example 2 of the present invention and Comparative Example 6. [Figure 11] FIG. 10 is a graph showing the cycle retention rates of battery cells pressed using battery cell pressure pads according to Example 2 of the present invention and Comparative Example 6. [Figure 12] FIG. 10 is a diagram showing the charge / discharge rates of battery cells pressed using battery cell pressure pads according to Example 1 of the present invention and Comparative Example 7. [Figure 13] FIG. 10 is a graph showing the cycle retention rates of battery cells pressed using battery cell pressure pads according to Example 1 of the present invention and Comparative Example 7. DETAILED DESCRIPTION OF THE INVENTION

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, some or all of the components may be exaggerated for ease of explanation.

[0033] Furthermore, it will be apparent to those skilled in the art that the present invention is not limited to the accompanying drawings or the contents described in this specification, and that the present invention can be realized in various forms without departing from the technical spirit of the present invention.

[0034] In the manufacturing process of an all-solid-state battery, contact between the interfaces of the electrodes and the solid electrolyte is important for improving battery performance such as initial charge-discharge efficiency and charge-discharge cycle performance, and a process of pressurizing the battery cell at a high pressure is necessary to achieve this contact between the interfaces of the electrodes and the solid electrolyte. That is, in the manufacturing process of an all-solid-state battery, applying uniform pressure to the battery cell during the pressurizing process facilitates the movement of lithium ions.

[0035] However, in order to improve contact between the positive and negative electrodes and the solid electrolyte, charging or discharging is performed while applying clamping pressure to the battery cell. If uneven pressure is applied to parts of the battery cell at this time, this can lead to problems such as a decrease in cell life performance and a decrease in initial charge / discharge efficiency.

[0036] To solve this problem, the inventors have developed a battery cell pressure pad that can improve contact between the electrodes and the solid electrolyte during the pressure process and apply uniform pressure to the battery cell.

[0037] Before describing the battery cell pressure pad according to an embodiment of the present invention in detail, the structure of the battery cell that is pressed by the pressure pad will be briefly described.

[0038] The battery cell according to the present invention may include a first electrode, an electrolyte layer, and a second electrode, which are sequentially stacked. Here, the first electrode may be a positive electrode or a negative electrode. The second electrode may be a negative electrode or a positive electrode. The first electrode and the second electrode may be different electrodes.

[0039] The electrolyte layer is disposed between the first electrode and the second electrode and may have an area equal to or larger than the first and second electrodes. Here, the electrolyte layer may be a solid electrolyte, but is not limited to these examples.

[0040] The battery cell may include a pouch film on its outermost shell.

[0041] FIG. 1 is a schematic diagram showing a battery cell pressure pad according to one embodiment of the present invention.

[0042] Referring to FIG. 1, a battery cell pressure pad according to one embodiment of the present invention may include a first pressure pad (101) that presses a battery cell (10) having electrodes and a solid electrolyte stacked thereon, contacts one side of the battery cell (10), and presses the one side of the battery cell (10), and a second pressure pad (102) that is stacked on the first pressure pad and contacts one side of a pressure jig (20).

[0043] FIG. 2 is a schematic diagram showing a battery cell pressure pad according to one embodiment of the present invention.

[0044] 2, in a battery cell pressure pad according to an embodiment of the present invention, a first pressure pad (101) presses both sides of a battery cell (10) with the battery cell (10) therebetween, and includes a first pressure pad (101-1) that presses one side of the battery cell and a first pressure pad (101-2) that presses the other side of the battery cell. The one side and the other side of the battery cell may be opposite sides.

[0045] In addition, in the battery cell pressure pad according to one embodiment of the present invention, the second pressure pad includes a 2-1 pressure pad (102-1) stacked on the 1-1 pressure pad and a 2-2 pressure pad (102-2) stacked on the 1-2 pressure pad, and the 2-1 pressure pad (102-1) and the 2-2 pressure pad (102-2) may each contact one side of the pressure jigs (20, 20') facing each other.

[0046] The battery cell pressure pad according to an embodiment of the present invention includes a first pressure pad and a second pressure pad, and thus can apply uniform pressure to the battery cell by the pressure pads having different physical properties.

[0047] In one embodiment of the battery cell pressure pad, the first and second pressure pads may have a CFD (Compression Force Deflection) 60% value of 4,000 kPa or greater. Here, CFD (Compression Force Deflection) refers to the compression force deflection, which is a measure of the force required to compress the pressure pad at a specific deformation rate (e.g., 50%, 60%). CFD values ​​are used to characterize the firmness and softness of a material and measure its physical properties. In addition, in the relationship between stress and strain on a material, compression indicates the type of force, and deflection indicates the amount of movement from a starting value (thickness).

[0048] Specifically, the CFD60% values ​​of the first pressure pad and the second pressure pad are 4,000 kPa or more, 4,100 kPa or more, 4,200 kPa or more, 4,300 kPa or more, 4,400 kPa or more, 4,500 kPa or more, 4,600 kPa or more, 4,700 kPa or more, 4,800 kPa or more, 4,900 kPa or more, 5,000 kPa or more, 5,100 kPa or more, 5,200 kPa or more, 5,300 kPa or more, 5, It may be 400 kPa or more, 5,500 kPa or more, 5,600 kPa or more, 5,700 kPa or more, 5,800 kPa or more, 5,900 kPa or more, 6,000 kPa or more, 6,100 kPa or more, 6,200 kPa or more, 6,300 kPa or more, 6,400 kPa or more, 6,500 kPa or more, 6,600 kPa or more, 6,700 kPa or more, 6,800 kPa or more, 6,900 kPa or more, or 7,000 kPa or more.

[0049] In the battery cell pressure pad according to an embodiment of the present invention, the CFD60% value of the first pressure pad may be greater than the CFD60% value of the second pressure pad.

[0050] In the battery cell pressure pad according to one embodiment of the present invention, the CFD 60% value of the first pressure pad may be 7,000 kPa or more.

[0051] In the battery cell pressure pad according to one embodiment of the present invention, the thickness (T c The ratio of the thickness (T1) of the first pressure pad to the thickness (T2) of the battery cell may be 1:0.01 to 0.5. The thickness of the first pressure pad may be 1% to 50% of the thickness of the battery cell. Here, if the thickness of the first pressure pad is less than 1% or more than 50% of the thickness of the battery cell, it may be difficult to apply uniform pressure when pressing the battery cell.

[0052] In the battery cell pressure pad according to an embodiment of the present invention, the thickness (T1) of the first pressure pad may satisfy the following formula 1: [Formula 1] T1>T p -T u In the formula 1, T p is the thickness of the positive electrode in the battery cell, T u is the thickness of the pouch film inside the battery cell.

[0053] In the above formula 1, T p indicates the thickest part of the battery cell, and T u may indicate the thinnest part in the battery cell.

[0054] The thickness (T1) of the first pressure pad is T p -T u If the value is smaller than or equal to the first pressure pad, it may be difficult to apply uniform pressure to the battery cell when the first pressure pad presses the battery cell.

[0055] In the battery cell pressure pad according to an embodiment of the present invention, when the first pressure pad is compressed multiple times at a deformation rate of 80% based on the initial thickness, the thickness of the first pressure pad may decrease by 60% or more based on the initial thickness.

[0056] The first pressure pad may have increased rigidity as it is compressed multiple times at a high deformation rate based on its initial thickness, which indicates that the first pressure pad has excellent elastic restoring force.

[0057] In the battery cell pressure pad according to one embodiment of the present invention, the CFD 50% values ​​of the first pressure pad and the second pressure pad may be 2,000 kPa or more.

[0058] Specifically, the CFD50% values ​​of the first pressure pad and the second pressure pad may be 2,000 kPa or more, 2,100 kPa or more, 2,200 kPa or more, 2,300 kPa or more, 2,400 kPa or more, 2,500 kPa or more, 2,600 kPa or more, 2,700 kPa or more, 2,800 kPa or more, 2,900 kPa or more, 3,000 kPa or more, 3,100 kPa or more, 3,200 kPa or more, 3,300 kPa or more, 3,400 kPa or more, 3,500 kPa or more, 3,600 kPa or more, 3,700 kPa or more, 3,800 kPa or more, 3,900 kPa or more, or 4,000 kPa or more.

[0059] In the battery cell pressure pad according to an embodiment of the present invention, the CFD50% value of the first pressure pad may be greater than the CFD50% value of the second pressure pad.

[0060] In the battery cell pressure pad according to one embodiment of the present invention, the CFD 50% value of the first pressure pad may be 3,000 kPa or more.

[0061] A CFD50% value or a CFD60% value of the first pressure pad being greater than a CFD50% value or a CFD60% value of the second pressure pad may mean that the first pressure pad is firmer and less ductile than the second pressure pad.

[0062] In the battery cell pressure pad according to one embodiment of the present invention, the first pressure pad and the second pressure pad may be made of any one of polytetrafluoroethylene (PTFE), silicone, organic rubber, polyurethane, polystyrene, polyethylene, polypropylene, ethylene vinyl acetate (EVA), and polyethylene terephthalate (PET), but are not limited to these examples.

[0063] The battery cell pressure pad according to an embodiment of the present invention can be attached to one side of a pressure jig that pressurizes a battery cell. Furthermore, the battery cell pressure pad can be used by contacting the battery cell pressure pad with the surface of the battery cell before pressing the battery cell, and then pressing the battery cell with the pressure jig. Therefore, there are no limitations on the manner in which the battery cell pressure pad can be used, and there are also no limitations on the type of jig that can be used to pressurize the battery cell.

[0064] An embodiment of the present invention may provide a battery cell pressing device including the battery cell pressing pad. The shape of the battery cell pressing device is not limited.

[0065] The battery cell pressure device may be configured to place the battery cells between the battery cell pressure pads, so that the battery cells can be uniformly pressurized by the battery cell pressure pads according to an embodiment of the present invention.

[0066] The battery cell pressurizing device can apply uniaxial or isotropic pressure to the battery cells.

[0067] Preferred examples will be described below to aid in understanding the present invention. However, the following examples are merely illustrative of the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope of the scope and technical idea of ​​the present invention. Naturally, such changes and modifications also fall within the scope of the appended claims.

[0068] Example 1 The pressure pad was fabricated by laminating a 0.5 mm polytetrafluoroethylene (PTFE) and a 0.3 mm silicone layer.

[0069] <Example 2> The pressure pads were manufactured by laminating 0.5 mm of polytetrafluoroethylene (PTFE) and 0.3 mm of silicone layers, and each pressure pad was manufactured to have a CFD 60% value of 4,000 kPa or more.

[0070] <Comparative Example 1> The pressure pad was made using only 0.5 mm of polytetrafluoroethylene (PTFE).

[0071] <Comparative Example 2> The pressure pad was manufactured using only a 0.3 mm silicone layer.

[0072] <Comparative Example 3> The pressure pad was made using only 0.5 mm of polyurethane (PU).

[0073] <Comparative Example 4> The pressure pad was made using only 1.0 mm polyurethane (PU).

[0074] <Comparative Example 5> A pressure pad was manufactured using a 0.5 mm polytetrafluoroethylene (PTFE) layer and a 0.3 mm silicone layer, but the layering order was changed from that of the pressure pad manufactured in the previous example.

[0075] <Comparative Example 6> The pressure pads were manufactured using 0.5 mm of polytetrafluoroethylene (PTFE) and 0.2 mm of polyurethane (PU), and each pressure pad was manufactured to have a CFD60% value of 4,000 kPa or more.

[0076] <Comparative Example 7> The pressure pad was fabricated using a 1.0 mm polytetrafluoroethylene (PTFE) and 0.3 mm silicone layer.

[0077] Experimental example 1: Battery cell performance evaluation The battery cells were pressurized using the pressure pads, spring jigs, and torque wrenches manufactured in Example 1 and Comparative Examples 1 and 2. The battery cell performance, such as the charge / discharge rate and cycle maintenance rate of the cells when fastened, was evaluated. The battery cell performance is shown in Figures 3 and 4.

[0078] 3 is a graph showing the charge / discharge rates of battery cells pressurized using battery cell pressure pads according to an embodiment of the present invention and comparative examples 1 and 2. Here, C rate is a value indicating the rate at which a battery is charged or discharged, and refers to the charge / discharge rate.

[0079] Referring to FIG. 3, it was confirmed that the charge / discharge rate of the battery cell pressed using the battery cell pressure pad according to Example 1 was lower than the charge / discharge rate at a high rate (1C) of the battery cell pressed using the battery cell pressure pad according to Comparative Example 1, but higher than the charge / discharge rate of the battery cell pressed using the battery cell pressure pad according to Comparative Example 2.

[0080] FIG. 4 is a graph showing the cycle maintenance rates of battery cells pressed using the battery cell pressure pads according to Example 1 of the present invention and Comparative Examples 1 and 2.

[0081] Referring to FIG. 4, it was confirmed that the cycle retention of the battery cell compressed using the battery cell pressure pad according to Example 1 decreased at a constant rate as multiple cycles were repeated, whereas the cycle retention of the battery cell compressed using the battery cell pressure pad according to Comparative Example 1 caused a short circuit in the initial cycle, and the cycle retention of the battery cell compressed using the battery cell pressure pad according to Comparative Example 2 increased as multiple cycles were repeated and then decreased again, showing unstable retention rates.

[0082] Therefore, it was found that using two types of pressure pads, such as the battery cell pressure pad of Example 1, allows for more uniform pressure to be applied to the battery cell than using only one pressure pad, such as the battery cell pressure pads of Comparative Examples 1 and 2, and improves the charge / discharge rate and cycle retention rate of the cell.

[0083] Experimental example 2: Battery cell performance evaluation The battery cells were pressurized using the pressure pads, spring jigs, and torque wrenches manufactured in Example 1 and Comparative Examples 3 and 4. The battery cell performance, such as the charge / discharge rate and cycle maintenance rate of the cells when fastened, was evaluated. The battery cell performance is shown in Figures 5 and 6.

[0084] 5 is a diagram showing the charge / discharge rates of battery cells pressurized using the battery cell pressure pads according to Example 1 of the present invention and Comparative Examples 3 and 4. Here, C rate is a value indicating the rate at which a battery is charged or discharged, and refers to the charge / discharge rate.

[0085] Referring to FIG. 5, it was confirmed that the charge / discharge rate of the battery cell pressed using the battery cell pressure pad according to Example 1 was slightly lower than the charge / discharge rate at a high rate (1C) of the battery cell pressed using the battery cell pressure pad according to Comparative Example 3, but was higher than the charge / discharge rate of the battery cell pressed using the battery cell pressure pad according to Comparative Example 4.

[0086] FIG. 6 is a graph showing the cycle maintenance rates of battery cells pressed using the battery cell pressure pads according to Example 1 of the present invention and Comparative Examples 3 and 4.

[0087] Referring to FIG. 6, it was confirmed that the cycle retention of the battery cell pressurized using the battery cell pressure pad according to Example 1 decreased at a constant rate as multiple cycles were repeated, whereas the cycle retention of the battery cell pressurized using the battery cell pressure pad according to Comparative Example 3 caused a short circuit after about 50 cycles, and the cycle retention of the battery cell pressurized using the battery cell pressure pad according to Comparative Example 4 showed a large deviation as multiple cycles were repeated.

[0088] Therefore, it was found that using two types of pressure pads with different ductility and firmness, such as the battery cell pressure pad of Example 1, allows for more uniform pressure to be applied when pressing the battery cell, improving the charge / discharge rate and cycle maintenance rate of the cell, compared to using only a pressure pad with low ductility (softness), such as the battery cell pressure pad of Comparative Examples 3 and 4.

[0089] Experimental example 3: Battery cell performance evaluation The battery cells were pressurized using the pressure pads, spring jigs, and torque wrenches manufactured in Example 1 and Comparative Example 5. The battery cell performance, such as the charge / discharge rate and cycle maintenance rate of the cells when fastened, was evaluated. The battery cell performance is shown in FIGS. 7 and 8.

[0090] 7 is a diagram showing the charge / discharge rates of battery cells pressurized using the battery cell pressure pads according to Example 1 of the present invention and Comparative Example 5. Here, C rate is a value indicating the rate at which a battery is charged or discharged, and refers to the charge / discharge rate.

[0091] Referring to FIG. 7, it was confirmed that the charge / discharge rate of the battery cell pressed using the battery cell pressure pad according to Comparative Example 5 was significantly lower than the charge / discharge rate at a high rate (1C) of the battery cell pressed using the battery cell pressure pad according to Example 1.

[0092] FIG. 8 is a graph showing the cycle maintenance rates of battery cells pressed using the battery cell pressure pads according to Example 1 of the present invention and Comparative Example 5.

[0093] Referring to FIG. 8, it was confirmed that the cycle retention rate of the battery cell pressurized using the battery cell pressure pad according to Example 1 had a slightly smaller deviation from the cycle retention rate of the battery cell pressurized using the battery cell pressure pad according to Comparative Example 5 over multiple cycles.

[0094] Therefore, it was found that when the stacking order of the first and second pressure pads is changed as in the battery cell pressure pad of Comparative Example 5, the charge / discharge rate of the battery cell at a high rate (1C) drops significantly.

[0095] Experimental example 4: CFD (Compression Force Deflection) measurement of battery cell pressure pad Among the pressure pads manufactured in Example 1, 50 mm x 50 mm samples were prepared for the polytetrafluoroethylene used as the first pressure pad, the silicone layer used as the second pressure pad, and the pressure pads manufactured in Comparative Examples 3 and 4. The samples were placed on the lower compression plate of a compression tester and compressed at a rate of 50 mm per minute to measure stress according to the degree of compression. Specifically, the CFD values ​​of the pressure pads were measured using the ASTM D3574 standard test. The measured CFD values ​​of the pressure pads are listed in Table 1 below.

[0096] [Table 1]

[0097] Experimental example 5: Battery cell performance evaluation The battery cells were pressurized using the pressure pads manufactured in Example 2 and Comparative Example 6. The battery cell performance, such as the charge / discharge rate and cycle maintenance rate of the cells when fastened, was evaluated. The battery cell performance is shown in FIGS. 10 and 11.

[0098] FIG. 9 is a diagram showing the compression curve of the pressure pad according to Comparative Example 6 of the present invention. The compression curve graph of the PU pad used in Comparative Example 6 shows that the stress increases as the compression ratio increases. In particular, when the compression ratio is 40% or less, the stress is shown to be 2 MPa or less, but at around 50%, it rises sharply to 10 MPa.

[0099] 10 is a diagram showing the charge / discharge rates of battery cells pressurized using battery cell pressure pads according to Example 2 of the present invention and Comparative Example 6. Here, C rate is a value indicating the rate at which a battery is charged or discharged, and refers to the charge / discharge rate.

[0100] Referring to FIG. 10, it was confirmed that the charge / discharge rate of the battery cell pressed using the battery cell pressure pad according to Example 2 was approximately 4% or more higher than the charge / discharge rate at a high rate (1C) of the battery cell pressed using the battery cell pressure pad according to Comparative Example 6.

[0101] FIG. 11 is a graph showing the cycle maintenance rates of battery cells pressed using the battery cell pressure pads according to Example 2 of the present invention and Comparative Example 6.

[0102] Referring to FIG. 11, it was confirmed that the cycle retention of the battery cell pressurized using the battery cell pressure pad according to Example 2 decreased at a constant rate as multiple cycles were repeated, whereas the cycle retention of the battery cell pressurized using the battery cell pressure pad according to Comparative Example 6 showed a similar pattern in the initial cycles, but showed a difference of about 5% or more as the number of cycles increased.

[0103] Therefore, even when the CFD60% value is set to 4,000 kPa or more under the conditions of Comparative Example 6, it was found that the use of the battery cell pressure pad according to Example 2 allows for a more uniform pressure to be applied when pressurizing the battery cell, improving the charge / discharge rate and cycle retention rate of the cell.

[0104] Experimental Example 6: Battery cell performance evaluation The pressure pads manufactured in Example 1 and Comparative Example 7 were used to pressurize the battery cells to a depth of 0.5 mm. The battery cell performance, such as the charge / discharge rate and cycle maintenance rate of the cells when fastened, was evaluated. The battery cell performance is shown in FIGS. 12 and 13.

[0105] 12 is a diagram showing the charge / discharge rates of battery cells pressurized using the battery cell pressure pads according to Example 1 of the present invention and Comparative Example 7. Here, C rate is a value indicating the rate at which a battery is charged or discharged, and refers to the charge / discharge rate.

[0106] Referring to FIG. 12, it was confirmed that the charge / discharge rate of the battery cell pressed using the battery cell pressure pad according to Comparative Example 7 was significantly lower than the charge / discharge rate at a high rate (1C) of the battery cell pressed using the battery cell pressure pad according to Example 1.

[0107] FIG. 13 is a graph showing the cycle maintenance rates of battery cells pressed using the battery cell pressure pads according to Example 1 of the present invention and Comparative Example 7.

[0108] Referring to FIG. 13, it was confirmed that the cycle retention of the battery cell pressed using the battery cell pressure pad according to Example 1 decreased at a constant rate as multiple cycles were repeated, whereas the cycle retention of the battery cell pressed using the battery cell pressure pad according to Comparative Example 7 decreased rapidly within 10 cycles.

[0109] Therefore, it was found that when the thickness of the first pressure pad is greater than a certain value, as in the battery cell pressure pad according to Comparative Example 7, the charge / discharge rate and cycle maintenance rate of the battery cell are reduced.

[0110] Although one embodiment of the present invention has been described above as an example, the present invention is not limited to the above embodiment. Those skilled in the art will be able to appropriately modify and implement one embodiment of the present invention, such as omitting, changing, or replacing all or part of the configuration of the present invention, or adding other configurations, by referring to this specification and the accompanying drawings, without departing from the technical spirit of the present invention. Terms and expressions in this specification should be interpreted broadly and not in a restrictive sense. In this specification, the word "comprise" does not exclude the presence or addition of one or more other components other than the referenced components.

[0111] In this specification, the singular forms include the plural forms unless the context clearly indicates otherwise.

[0112] In this specification, the embodiments described as examples can be combined with each other, and unless contradictory, the content described in a particular embodiment can be applied to other embodiments in the same manner, even if it is not described in the other embodiments. [Explanation of symbols]

[0113] 10: Battery cell 20: Pressure jig 101: First pressure pad 101-1: No. 1-1 pressure pad 101-2: 1st and 2nd pressure pad 102: Second pressure pad 102-1: No. 2-1 pressure pad 102-2: No. 2-2 pressure pad

Claims

1. A battery cell pressure pad that applies pressure to a battery cell in which electrodes and a solid electrolyte are stacked, a first pressure pad that contacts one side of the battery cell and applies pressure to the one side of the battery cell; and a second pressure pad stacked on the first pressure pad and in contact with one side of the pressure jig.

2. The first pressure pad is The battery cell is placed between the two cells and pressed on both sides. a first pressure pad for applying pressure to one side of the battery cell; and The battery cell pressure pad of claim 1 , further comprising: a first pressure pad and a second pressure pad for applying pressure to the other side of the battery cell.

3. The second pressure pad is a second-first pressure pad laminated on the first-first pressure pad; and a second-second pressure pad laminated on the first-second pressure pad; The battery cell pressure pad of claim 2 , wherein the second-1 pressure pad and the second-2 pressure pad are in contact with respective sides of a pressure jig that face each other.

4. The battery cell pressure pad according to claim 1 , wherein the first pressure pad and the second pressure pad have a CFD (Compression Force Deflection) 60% value of 4,000 kPa or more.

5. The battery cell pressure pad of claim 1 , wherein the CFD60% value of the first pressure pad is greater than the CFD60% value of the second pressure pad.

6. The battery cell pressure pad of claim 1 , wherein the CFD 60% value of the first pressure pad is 7,000 kPa or greater.

7. The thickness of the battery cell (T ｃ ) and the thickness of the first pressure pad (T １ 2. The battery cell pressure pad of claim 1, wherein the ratio of the adhesive strength to the adhesive strength is 1:0.01-0.

5.

8. The thickness of the first pressure pad (T １ 2. The battery cell pressure pad according to claim 1, wherein the pressure applied to the battery cell satisfies the following formula 1: [Formula 1] T １ > T ｐ - T ｕ In the formula 1, T ｐ is the thickness of the positive electrode in the battery cell, T ｕ is the thickness of the pouch film inside the battery cell.

9. The battery cell pressure pad of claim 1 , wherein when the first pressure pad is compressed multiple times at a deformation rate of 80% of the initial thickness, the thickness of the first pressure pad is reduced by 60% or more of the initial thickness.

10. The battery cell pressure pad according to claim 1 , wherein the CFD50% values ​​of the first pressure pad and the second pressure pad are 2,000 kPa or more.

11. The battery cell pressure pad of claim 1 , wherein the CFD50% value of the first pressure pad is greater than the CFD50% value of the second pressure pad.

12. The battery cell pressure pad according to claim 1 , wherein the first pressure pad has a CFD (Compression Force Deflection) 50% value of 3,000 kPa or more.

13. A battery cell pressure device comprising the battery cell pressure pad according to any one of claims 1 to 12.

14. The battery cell pressure device according to claim 13 , wherein a battery cell is disposed between the battery cell pressure pads.

15. The battery cell pressurizing device according to claim 14 , wherein the battery cell is pressurized uniaxially or isotropically.

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