Method for isostatically pressing electrode assembly using protection member as outer sacrificial frame, and all-solid-state battery including protection member

Abstract

The present invention provides: a method for isostatically pressing an electrode assembly that comprises a positive electrode including a positive electrode current collector and a positive electrode active material layer, a negative electrode including a positive electrode current collector and a negative electrode active material layer, and a solid electrolyte layer, and has a laminated form in which the solid electrolyte layer is laminated on the negative electrode active material layer such that one surface of the solid electrolyte layer is bonded to the negative electrode active material layer, the positive electrode is laminated on the other surface of the solid electrolyte layer such that the positive electrode active material layer is bonded to the other surface of the solid electrolyte layer, and the negative electrode protrudes outside the end of the positive electrode to form a step, wherein isostatic pressing is performed in a state in which a band-shaped protection member extending vertically from the outer surface of the protruding end of the negative electrode to the positive electrode is fastened, and a space formed by the step is located between the protection member and the positive electrode; and an all-solid-state battery including the electrode assembly and the protection member.

Description

An isotropic pressing method for an electrode assembly using a protective member as an outer sacrificial frame and an all-solid-state battery including the protective member

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0129329, filed September 26, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an isotropic pressing method for an electrode assembly using a protective member as an outer sacrificial frame and an all-solid-state battery including the protective member.

[0003] Recently, secondary batteries have become indispensable as portable power sources for computers, mobile devices, etc., as power sources for driving vehicles such as electric vehicles (EVs), hybrid vehicles (HVs), and plug-in hybrid vehicles (PHVs), and as power sources for power storage.

[0004] In particular, lithium-ion batteries have high energy density and are capable of high-speed output, so their widespread use requires additional performance and improved reliability.

[0005] Recently, in order to improve the safety of lithium-ion secondary batteries, the practical application of all-solid-state batteries that use solid electrolytes made of ceramics or ion-conducting polymers instead of flammable electrolytes is in progress.

[0006] All-solid-state batteries consist of an electrode body formed by placing a layered solid electrolyte between a positive electrode active material layer and a negative electrode active material layer. These solid electrolyte layers and the positive and negative electrode active material layers can be formed as dense thin films using methods such as CVD. However, due to cost and productivity considerations, they are generally manufactured by binding powder-type electrode components with a binder.

[0007] All-solid-state batteries are characterized by high interfacial resistance between the solid electrolyte layer and the positive and negative active material layers. Furthermore, in all-solid-state batteries manufactured using powdered materials, interfacial resistance occurs between particles within the solid electrolyte layer and the positive and negative active material layers. Therefore, to reduce this interfacial resistance, a process is being performed in which an electrode body comprising a stack of positive active material layers, a solid electrolyte layer, and a negative active material layer is pressed at high pressure (e.g., 100 to 500 MPa in surface pressure) to improve the packing density of each layer.

[0008] When the electrode body is pressurized, a tensile stress may be applied in a direction orthogonal to the pressing direction, so that the ends of the positive active material layer and the negative active material layer, which face each other through the solid electrolyte layer, may come into contact, resulting in a short circuit. Therefore, in order to prevent the short circuit, it has been proposed to design one active material layer (e.g., the positive active material layer) to have a small width, for example. In addition, a configuration has been proposed in which the ends of the solid electrolyte layer or the positive and negative active material layers are covered with an insulator.

[0009] In addition, the pressurizing process is generally performed in an isotropic pressurizing manner, and at this time, high pressure is applied to the outermost edge of the cell, which causes the edge to become elongated and thin or rounded, and cracks occur in the electrode active material layer and the solid electrolyte layer.

[0010] [Prior Art Literature]

[0011] [Patent Document]

[0012] Japanese Special Publication No. 2015-050149

[0013]

[0014] The present invention has been devised to solve the above problems of the prior art.

[0015] The purpose of the present invention is to provide an isotropic pressing method for an electrode assembly, which prevents short circuits between the ends of a positive electrode active material layer and the ends of a negative electrode active material layer by applying a specific type of protective member as an outer sacrificial frame to the electrode assembly during an isotropic pressing process for an electrode assembly of an all-solid-state battery, and an all-solid-state battery including the protective member, and which prevents the outermost edge of the cell from becoming thin or rounded due to elongation.

[0016] In order to achieve the above purpose, the present invention

[0017] A positive electrode including a positive current collector and a positive active material layer, a negative electrode including a negative current collector and a negative active material layer, and a solid electrolyte layer,

[0018] A solid electrolyte layer is laminated so that one side is bonded to the negative electrode active material layer, and a positive electrode is laminated so that a positive electrode active material layer is bonded to the other side of the solid electrolyte layer.

[0019] An isotropic pressing method for an electrode assembly having a laminated form in which the cathode protrudes beyond the terminal end of the anode to form a step,

[0020] A method for isotropic pressing of an electrode assembly is provided, which performs isotropic pressing while attaching a band-shaped protective member extending vertically from the outer surface of the protruding cathode end of the electrode assembly to the anode.

[0021]

[0022] In addition, the present invention

[0023] A positive electrode including a positive current collector and a positive active material layer, a negative electrode including a negative current collector and a negative active material layer, and a solid electrolyte layer,

[0024] A solid electrolyte layer is laminated so that one side is bonded to the negative electrode active material layer, and a positive electrode is laminated so that a positive electrode active material layer is bonded to the other side of the solid electrolyte layer.

[0025] An electrode assembly having a laminated form in which the cathode protrudes beyond the terminal end of the anode to form a step; and

[0026] An all-solid-state battery is provided, including a band-shaped protective member extending vertically from the outer surface of the protruding negative electrode end portion of the above electrode assembly to the positive electrode.

[0027] The isostatic pressing method of the electrode assembly of the present invention prevents the occurrence of a short circuit due to a crack between the end of the positive electrode active material layer and the end of the negative electrode active material layer by applying a protective member of a specific shape as an outer sacrificial frame to the electrode assembly during the isostatic pressing process, and provides the effect of preventing the problem of the outermost edge of the cell from being elongated, thinned, or rounded.

[0028] In addition, the all-solid-state battery including the above-mentioned protective member prevents a short circuit between an end of a positive electrode active material layer and an end of a negative electrode active material layer, and prevents the outermost edge of the cell from becoming thin or rounded, thereby providing the effect of improving the safety and operating characteristics of the battery.

[0029] Figure 1 is a drawing showing a conventional electrode assembly isotropic pressing method.

[0030] Figure 2 is a drawing illustrating a problem that occurs due to the conventional isotropic pressurization method.

[0031] Figure 3 is a drawing illustrating one embodiment of the electrode assembly isotropic pressing method of the present invention.

[0032] Figure 4 is a cross-sectional view showing the shape of the electrode assembly of the present invention.

[0033] Figures 5 and 6 are drawings showing one embodiment in which the electrode assembly and the protective member of the present invention are combined.

[0034] Figure 7 is a drawing showing another embodiment in which the electrode assembly and the protective member of the present invention are combined.

[0035] Figures 8 and 9 are cross-sectional views illustrating one embodiment of an all-solid-state battery of the present invention.

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. Like reference numerals designate similar parts throughout the specification.

[0037] When a component is referred to as being "connected to, provided with, or installed" another component, it should be understood that it may be directly connected or installed to that other component, but there may also be other components in between. Conversely, when a component is referred to as being "directly connected to, provided with, or installed" another component, it should be understood that there are no other components in between. Similarly, other expressions describing the relationship between components, such as "on top of" and "directly on top of," "between" and "directly between," or "adjacent to" and "directly adjacent to," should be interpreted similarly.

[0038] As shown in FIG. 3 and FIG. 5, the isotropic pressing method of the electrode assembly (50) of the present invention

[0039] It includes a positive electrode (10) including a positive electrode current collector (12) and a positive electrode active material layer (14), a negative electrode (20) including a negative electrode current collector (22) and a negative electrode active material layer (24), and a solid electrolyte layer (30).

[0040] A solid electrolyte layer (30) is laminated so that one side is bonded to the negative electrode active material layer (24), and a positive electrode (10) is laminated so that a positive electrode active material layer (14) is bonded to the other side of the solid electrolyte layer (30).

[0041] As an isotropic pressing method of an electrode assembly (50) having a laminated form in which the cathode (20) protrudes out of the end of the anode (10) to form a step,

[0042] It is characterized in that isostatic pressing is performed in a state in which a band-shaped protective member (40) extending vertically from the outer surface of the protruding cathode (20) end of the above electrode assembly (100) to the anode (10) is fastened.

[0043] In one embodiment of the present invention, the protective member (40) above may extend, for example, to the outermost surface of the positive electrode collector (12).

[0044] In one embodiment of the present invention, when the electrode assembly (100) is in a bi-cell shape as shown in FIG. 8,

[0045] The above electrode assembly (100) is laminated so that a solid electrolyte layer (30) is bonded to one side of the negative electrode active material layer (24) of the negative electrode current collector (22), and the positive electrode (10) is laminated so that a positive electrode active material layer (14) is bonded to the other side of each of the solid electrolyte layers (30).

[0046] The above protective member (40) may be in the form of a band extending vertically to the outer surface of the terminal end of the negative electrode (20) protruding from the electrode assembly (100) and extending to the outermost surface of both positive electrode current collectors (12).

[0047] The electrode assembly (50) to which the above protective member (40) is attached is, as shown in FIG. 3, housed inside a pouch case (60) or an isostatic pressing film (70) and is fixed to an isostatic pressing jig (200) and pressurized.

[0048] As shown in FIGS. 1 and 2, the conventional isotropic pressing method of the electrode assembly (50) has a problem in that, when the electrode assembly is isotropically pressed, a tensile stress is applied in a direction orthogonal to the pressing direction, and a crack occurs, causing the ends of the positive active material layer and the negative active material layer, which face each other through the solid electrolyte layer, to come into contact, resulting in a short circuit. In addition, there is a problem in that the edges of the electrode assembly are stretched and thinned or rounded, and this causes cracks to occur in the electrode active material layer and the solid electrolyte layer.

[0049] The present invention is an invention that solves the above-mentioned problem, and is characterized in that isostatic pressing is performed in a state in which a band-shaped protective member (40) as shown in FIGS. 3 and 5 is fastened as an outer sacrificial frame.

[0050] In one embodiment of the present invention, the solid electrolyte layer (30) is laminated over the entire area of ​​the negative electrode active material layer (24), and accordingly, the step may also be formed between the solid electrolyte layer (30) and the positive electrode (10).

[0051] In one embodiment of the present invention, a space formed by the step may be located between the protective member (40) and the anode (10), as illustrated in FIGS. 3 and 5. The space formed by the step acts as a space that buffers the high pressure applied by isotropic pressing, thereby preventing the outermost edge portion of the electrode assembly (50) from being stretched and thinned or rounded, and the occurrence of cracks in the electrode active material layer and the solid electrolyte layer.

[0052] In one embodiment of the present invention, the protective member (40) has the characteristic of being easily attached to or removed from the electrode assembly (50) during isostatic pressing. That is, the protective member can be accommodated in a battery case such as a pouch while being attached to the electrode assembly, but in some cases, it can be removed after isostatic pressing. In this case, a band-shaped protective member (40) such as that of the present invention is preferable because it is easy to attach and remove and can be recycled.

[0053] In one embodiment of the present invention, the space formed by the step may be filled with a transverse extension (42) of the protective member (40), as illustrated in FIG. 7. The transverse extension (42) fills the space formed by the step, thereby preventing the problem of the outermost edge portion of the electrode assembly (50) being stretched and thinned or rounded due to high pressure, and the problem of cracks occurring in the electrode active material layer and the solid electrolyte layer.

[0054]

[0055] In one embodiment of the present invention, it is preferable that the protective member (40) has a shrinkage range that is the same as or similar to the extent to which the electrode assembly shrinks due to pressure. Specifically, it may be preferable that the protective member (40) shrinks due to pressure by 0.8 to 1.2 times, preferably 0.9 to 1.1 times, the extent to which the electrode assembly shrinks due to pressure.

[0056] For example, CFD (compression force deflection) 50% can be used as 2000 to 4000 kPa. The CFD measurement method is one of the methods for evaluating the hardness of a material, and for example, if a force of 3000 kPa is required to shrink the material to 50% of its initial thickness, CFD 50% is defined as 3000 kPa.

[0057]

[0058] The protective member (40) may preferably be extended vertically from the outer surface of the protruding end of the negative electrode (20) in the electrode assembly (100) to the outermost surface of the positive electrode collector (10), but considering elasticity, it may also be extended slightly higher than the outermost surface of the positive electrode collector (12). In this case, when high pressure is applied by isostatic pressing, the protective member (40) may be compressed by elasticity and provide the effect aimed at in the present invention. Specifically, it may be preferably used to have a length that is compressed during isostatic pressing and compresses to the outermost surface of the positive electrode collector (10). In addition, the same or similar effect may be expected even when extended to a position slightly lower than the outermost surface of the positive electrode collector (12).

[0059] In one embodiment of the present invention, the material of the protective member is not particularly limited, but, for example, a polymer material such as rubber, silicone, Gore-Tex, PVC, or EVA can be preferably used.

[0060] In one embodiment of the present invention, a through hole or groove may be formed in the protective member (40) so that the negative tab formed in the negative electrode current collector (22) and the positive tab formed in the positive electrode current collector (12) protrude outside the protective member (40), as shown in FIGS. 5 and 7.

[0061]

[0062] The present invention also, as shown in FIG. 8,

[0063] A cathode (10) including a cathode current collector (12) and a cathode active material layer (14),

[0064] A negative electrode (20) including a negative electrode current collector (22) and a negative electrode active material layer (24), and

[0065] It includes a solid electrolyte layer (30),

[0066] A solid electrolyte layer (30) is laminated so that one side is bonded to the negative electrode active material layer (24), and a positive electrode (10) is laminated so that a positive electrode active material layer (14) is bonded to the other side of the solid electrolyte layer (30).

[0067] An electrode assembly (50) having a laminated form in which the cathode (20) protrudes out of the end of the anode (10) to form a step; and

[0068] An all-solid-state battery is provided, including a band-shaped protective member (40) extending vertically from the outer surface of the protruding end of the cathode (20) in the above electrode assembly (100) to the anode (10).

[0069] In one embodiment of the present invention, when the electrode assembly (100) is in a bi-cell shape as shown in FIG. 8,

[0070] The above electrode assembly (100) is laminated so that a solid electrolyte layer (30) is bonded to one side of the negative electrode active material layer (24) of the negative electrode current collector (22), and the positive electrode (10) is laminated so that a positive electrode active material layer (14) is bonded to the other side of each of the solid electrolyte layers (30).

[0071] The above protective member (40) may be in the form of a band extending vertically to the outer surface of the terminal end of the negative electrode (20) protruding from the electrode assembly (100) and extending to the outermost surface of both positive electrode current collectors (12).

[0072] As for the all-solid-state battery of the present invention, all of the contents described in the isotropic pressing method described above can be applied, so description of overlapping contents is omitted.

[0073] In one embodiment of the present invention, the solid electrolyte layer (30) is laminated over the entire area of ​​the negative electrode active material layer (24), and accordingly, the step may also be formed between the solid electrolyte layer (30) and the positive electrode (10).

[0074] In one embodiment of the present invention, a space formed by the step may be located between the protective member (40) and the anode (10).

[0075] The above-mentioned all-solid-state battery (100) may have a structure in which the electrode assembly (50) and the protective member (40) are assembled and stored in a battery case such as a pouch case, as shown in FIG. 8.

[0076] In one embodiment of the present invention, it is preferable that the protective member (40) has a shrinkage range that is the same as or similar to the extent to which the electrode assembly shrinks due to pressure. Specifically, it may be preferable that the protective member (40) shrinks due to pressure by 0.8 to 1.2 times, preferably 0.9 to 1.1 times, the extent to which the electrode assembly shrinks due to pressure.

[0077] For example, CFD (compression force deflection) 50% can be used as 2000 to 4000 kPa. The CFD measurement method is one of the methods for evaluating the hardness of a material, and for example, if a force of 3000 kPa is required to shrink the material to 50% of its initial thickness, CFD 50% is defined as 3000 kPa.

[0078] The protective member (40) may preferably be extended vertically from the outer surface of the protruding end of the negative electrode (20) in the electrode assembly (100) to the outermost surface of the positive electrode collector (10), but considering elasticity, it may also be extended slightly higher than the outermost surface of the positive electrode collector (12). In this case, when high pressure is applied by isostatic pressing, the protective member (40) may be compressed by elasticity to provide the effect aimed at in the present invention. Specifically, it may be preferably used to have a length compressed to the outermost surface of the positive electrode collector (10) during isostatic pressing. In addition, the same or similar effect may be expected even when extended to a position slightly lower than the outermost surface of the positive electrode collector (12).

[0079] In one embodiment of the present invention, the all-solid-state battery may be a lithium-ion all-solid-state battery.

[0080]

[0081] Although the present invention has been described in connection with the preferred embodiments mentioned above,

[0082] Various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the appended claims shall encompass such modifications and variations as long as they fall within the spirit and scope of the present invention.

[0083] [Explanation of symbols]

[0084] 10: Positive 10: Positive

[0085] 12: Cathode current collector 14: Cathode active material layer

[0086] 20: Cathode 32: Cathode current collector

[0087] 34: Negative active material layer 40: Protective member

[0088] 42: Transverse extension of protective member 50: Electrode assembly

[0089] 60: Pouch case 70: Film for isostatic pressing

[0090] 100: All-solid-state battery 200: Jig for isostatic pressing

Claims

1. A positive electrode including a positive electrode current collector and a positive electrode active material layer, a negative electrode including a negative electrode current collector and a negative electrode active material layer, and a solid electrolyte layer, A solid electrolyte layer is laminated so that one side is bonded to the negative electrode active material layer, and a positive electrode is laminated so that a positive electrode active material layer is bonded to the other side of the solid electrolyte layer. An isotropic pressing method for an electrode assembly having a laminated form in which the cathode protrudes beyond the terminal end of the anode to form a step, In the above electrode assembly, isostatic pressing is performed while a band-shaped protective member extending vertically from the outer surface of the protruding cathode end to the anode is fastened. An isotropic pressing method for an electrode assembly, characterized in that a space formed by the step is located between the protective member and the anode.

2. In paragraph 1, An isostatic pressing method for an electrode assembly, characterized in that the electrode assembly to which the above protective member is attached is accommodated inside a pouch case or an isostatic pressing film and is pressed while being fixed to an isostatic pressing jig.

3. In paragraph 1, An isotropic pressing method for an electrode assembly, characterized in that the solid electrolyte layer is laminated over the entire area of ​​the negative electrode active material layer, and accordingly, the step is also formed between the solid electrolyte layer and the positive electrode.

4. In paragraph 1, An isotropic pressing method for an electrode assembly, characterized in that the above protective member shrinks by 0.8 to 1.2 times the amount of shrinkage of the electrode assembly due to pressing.

5. In paragraph 1, The above protective member is an isotropic pressurization method for an electrode assembly, characterized in that CFD (compression force deflection) 50% is 2000 to 4000 kPa.

6. In paragraph 1, An isotropic pressing method for an electrode assembly, characterized in that the above protective member is manufactured from at least one selected from rubber, silicone, Gore-Tex, and polymer materials.

7. A positive electrode including a positive electrode current collector and a positive electrode active material layer, a negative electrode including a negative electrode current collector and a negative electrode active material layer, and a solid electrolyte layer, A solid electrolyte layer is laminated so that one side is bonded to the negative electrode active material layer, and a positive electrode is laminated so that a positive electrode active material layer is bonded to the other side of the solid electrolyte layer. An electrode assembly having a laminated form in which the cathode protrudes beyond the terminal end of the anode to form a step; and A protective member in the form of a band extending vertically from the outer surface of the protruding cathode end of the above electrode assembly to the anode; An all-solid-state battery characterized in that a space formed by the step is located between the protective member and the positive electrode.

8. In paragraph 7, An all-solid-state battery characterized in that the solid electrolyte layer is laminated over the entire area of ​​the negative electrode active material layer, and accordingly, the step is also formed between the solid electrolyte layer and the positive electrode.

9. In paragraph 7, An all-solid-state battery characterized in that the above all-solid-state battery is a lithium-ion all-solid-state battery.

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