Method for manufacturing non-aqueous electrolyte secondary battery

Abstract

To provide a method for manufacturing a non-aqueous electrolyte secondary battery capable of suppressing a decrease in impregnation properties of an electrolyte and / or a decrease in defoaming properties of gas when the electrolyte is injected.SOLUTION: The method for manufacturing a non-aqueous electrolyte secondary battery including a battery case, an electrode body housed in the battery case, and an electrolyte includes the steps of: attaching a liquid-injection mechanism to the battery case; and, in a state in which the electrolyte is injected into the battery case from an injection port of the liquid-injection mechanism, [i] injecting the electrolyte from the liquid-injection mechanism to fill the inside of the battery case with the electrolyte; and [ii] storing and holding, in the liquid-injection mechanism, surplus electrolyte that has not been injected into the battery case. The separator included in the electrode body has a porous base material and a functional layer. The functional layer includes a first layer partially present on a surface of at least one side of the separator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery. [Background technology]

[0002] In order to improve the adhesion between the electrode and the separator, the electrode and the separator substrate may be bonded together using an adhesive layer (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-138768 Summary of the Invention [Problem to be solved by the invention]

[0004] When the adhesion between the electrodes and the separator is improved as described above, the impregnation of the electrolyte may be reduced, and the defoaming of gas inside the battery case when the electrolyte is injected may be reduced.

[0005] An object of the present disclosure is to provide a method for producing a nonaqueous electrolyte secondary battery that can suppress a decrease in impregnation of an electrolyte solution and / or a decrease in defoaming of gas when an electrolyte solution is injected. [Means for solving the problem]

[0006] [1] A method for manufacturing a nonaqueous electrolyte secondary battery including a battery case, and an electrode assembly and an electrolyte solution housed in the battery case, the electrode assembly includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; the separator has a porous substrate and a functional layer, the functional layer includes a first layer partially present on at least one surface of the separator, The manufacturing method for a nonaqueous electrolyte secondary battery includes attaching an injection mechanism to the battery case, and in a state in which the electrolyte is injected into the battery case from an injection port of the injection mechanism, (i) injecting the electrolyte from the injection mechanism to fill the battery case with the electrolyte, and (ii) storing and holding surplus electrolyte that has not been injected into the battery case in the injection mechanism. [2] The electrode body has a rectangular shape when viewed from the stacking direction of the positive electrode, the negative electrode, and the separator, [1] The method for producing a nonaqueous electrolyte secondary battery according to [1], wherein the length of the positive electrode active material layer of the positive electrode or the negative electrode active material layer of the negative electrode in a direction parallel to a long side of the rectangle is 150 mm or more. [3] The method for producing a nonaqueous electrolyte secondary battery according to [2], wherein the liquid filling port is formed in at least one wall surface of the battery case that intersects with the long sides when extended. [4] The method for producing a nonaqueous electrolyte secondary battery according to any one of [1] to [3], wherein the first layer is present in a stripe or dot pattern on the surface of the at least one side. [5] The electrode body is a laminated electrode body, the first layer is present in a striped pattern on the surface of the at least one side, [4] The method for producing a nonaqueous electrolyte secondary battery according to any one of [1] to [4], wherein the extending direction of the stripes of the first layer is a direction parallel to or perpendicular to a wall surface of the battery case on which the liquid filling port is formed. [6] The method for producing a nonaqueous electrolyte secondary battery according to any one of [1] to [5], wherein after the steps [i] and [ii], an operation of reducing the pressure inside the battery case containing the electrode assembly and returning it to normal pressure is carried out at least once. [7] The first layer is partially present on each of the first and second surfaces of the separator, The method for producing a nonaqueous electrolyte secondary battery according to any one of [1] to [6], wherein the first layer on the first surface is present in a region corresponding to a region on the second surface where the first layer is not present. [8] The method for producing a nonaqueous electrolyte secondary battery according to any one of [1] to [7], wherein the first layer has a thickness of 0.5 μm or more. [9] The method for producing a nonaqueous electrolyte secondary battery according to any one of [1] to [8], wherein the first layer is an adhesive layer or a layer containing inorganic particles.

[10] The functional layer has a second layer between the first layer and the substrate, The method for producing a nonaqueous electrolyte secondary battery according to any one of [1] to [9], wherein the second layer has a region that is not covered by the first layer.

[11] The method for producing a nonaqueous electrolyte secondary battery according to

[10] , wherein the second layer covers the entire surface of the substrate on the side of the separator where the first layer is present.

[12] The method for producing a nonaqueous electrolyte secondary battery according to

[10] or

[11] , wherein the second layer is an adhesive layer or a layer containing inorganic particles. [Effects of the Invention]

[0007] According to the present disclosure, a nonaqueous electrolyte secondary battery can be manufactured while suppressing a decrease in the impregnation of the electrolyte solution and / or a decrease in the defoaming of gas when the electrolyte solution is injected. [Brief explanation of the drawings]

[0008] [Figure 1] 2A to 2C are cross-sectional views schematically illustrating an example of a manufacturing process for a nonaqueous electrolyte secondary battery according to an embodiment. [Figure 2] 5A to 5C are cross-sectional views schematically illustrating another example of the manufacturing process of the nonaqueous electrolyte secondary battery according to the embodiment. [Figure 3] 1 is a cross-sectional view schematically illustrating an example of a separator included in a nonaqueous electrolyte secondary battery according to an embodiment. [Figure 4] FIG. 3 is a cross-sectional view schematically illustrating another example of a separator included in the nonaqueous electrolyte secondary battery according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] In this specification, unless otherwise specified, a numerical range such as "x to y" includes both the upper and lower limits. That is, "x to y" represents a numerical range of "greater than or equal to x and less than or equal to y." A numerical value arbitrarily selected from within the numerical range may be set as a new upper or lower limit. For example, a new numerical range may be set by arbitrarily combining a numerical value within the numerical range with a numerical value described elsewhere in this specification, in a table, or in a figure.

[0010] 1 and 2 are cross-sectional views schematically showing a manufacturing process of a nonaqueous electrolyte secondary battery according to an embodiment, and Fig. 3 and Fig. 4 are cross-sectional views schematically showing a separator included in the nonaqueous electrolyte secondary battery according to an embodiment.

[0011] The nonaqueous electrolyte secondary battery of this embodiment (hereinafter also referred to as "the battery") is, for example, a lithium ion secondary battery that charges and discharges by absorbing and releasing lithium ions. The battery includes a battery case 17, and an electrode assembly 1 and an electrolyte solution 30 housed in the battery case 17 (FIGS. 1 and 2).

[0012] The battery case 17 can have an exterior body, which is a housing that houses the electrode assembly 1 and the electrolyte solution 30, and a sealing plate that seals the opening of the exterior body. The exterior body and the sealing plate are made of known materials such as metal materials. The battery case 17 has a liquid filling port 18, which is an opening that penetrates the battery case 17 and is used to fill the electrolyte solution 30. The liquid filling port 18 may be formed in the exterior body or in the sealing plate. The battery case 17 usually has one liquid filling port 18, but may have two or more liquid filling ports.

[0013] The electrode assembly 1 has a positive electrode, a negative electrode, and a separator 10 (FIGS. 3 and 4) interposed between the positive and negative electrodes. The positive electrode, for example, has a positive electrode active material layer containing a positive electrode active material on a positive electrode current collector. The negative electrode, for example, has a negative electrode active material layer containing a negative electrode active material on a negative electrode current collector. The positive electrode current collector, positive electrode active material, positive electrode active material layer, negative electrode current collector, negative electrode active material, and negative electrode active material layer can be formed using known materials. The electrode assembly 1 may be a wound type electrode assembly or a stacked type electrode assembly, but in this method, a stacked type electrode assembly is preferred. In the stacked type electrode assembly, the separator 10 may be long and folded in a zigzag shape (snake-folded shape) in the longitudinal direction, with positive electrodes and negative electrodes alternately inserted between the folded portions.

[0014] The separator 10 has a porous substrate 11 and a functional layer 12. The substrate 11 is, for example, a porous sheet of film or nonwoven fabric formed using a known resin such as polyolefin. The substrate 11 may have a single-layer structure or a multi-layer structure of two or more layers. As described below, the functional layer 12 includes a first layer 15 partially present on at least one surface of the separator 10, and may also include a second layer 16 (FIGS. 3 and 4). The functional layer 12 may be an adhesive layer or a layer containing inorganic particles, or may include both. The layer containing inorganic particles may be a heat-resistant layer.

[0015] The electrolytic solution 30 is, for example, a non-aqueous electrolytic solution, preferably an electrolyte contained in a non-aqueous solvent such as an organic solvent. The electrolytic solution 30 may contain one or more non-aqueous solvents and one or more electrolytes. Known materials can be used for the non-aqueous solvent and the electrolyte.

[0016] The manufacturing method of this battery (hereinafter also referred to as "this method") involves attaching a liquid injection mechanism 20 to a battery case 17, injecting electrolyte 30 into the battery case 17 through an injection port 18 of the liquid injection mechanism 20, [i] injecting the electrolyte 30 from the liquid injection mechanism 20 to fill the battery case 17 with the electrolyte 30, and [ii] storing and retaining excess electrolyte 31 that has not been injected into the battery case 17 within the liquid injection mechanism 20.

[0017] The injection mechanism 20 is preferably a funnel-shaped injection mechanism, such as a funnel or a hopper. The injection mechanism 20 typically includes a main body 21 and an outlet 22 connected to the main body 21. The injection mechanism 20 may further include a valve (not shown) attached to the outlet 22. This valve may be switched between an open state, allowing the electrolyte 30 to flow from the injection mechanism 20, and a closed state, preventing the flow. The amount of the electrolyte 30 flowing out may be adjusted by adjusting the degree of opening of the valve. The main body 21 has a space capable of storing the electrolyte 30. For example, the diameter of at least the side opposite the outlet 22 (hereinafter also referred to as the "inlet side") is larger than the diameter of the outlet 22 side (hereinafter also referred to as the "outlet side") (FIGS. 1 and 2). The shape of the main body 21 may be a shape whose diameter gradually decreases from the inlet side to the outlet side (e.g., a cone, a pyramid, a hemisphere, an elliptical hemisphere, etc.), or a shape whose diameter is constant from the inlet side to the outlet side (e.g., a cylindrical shape, a prismatic shape, etc.). Outlet part 22 is formed in a tubular shape connected to the outflow side of main body 21, and can be attached to inlet 18 of battery case 17 to inject electrolyte 30. Outlet part 22 may be formed in a straight tubular shape (FIG. 2), or in a curved tubular shape or a tubular shape with a bent portion (FIG. 1), depending on the arrangement when connecting inlet 18 of battery case 17 to inlet 18 of battery case 17, etc.

[0018] In this method, the state in which the injection mechanism 20 is attached to the battery case 17 and the electrolyte 30 is injected from the injection mechanism 20 into the battery case 17 refers to, for example, a state in which the outlet 22 of the injection mechanism 20 and the injection port 18 of the battery case 17 are connected so that the electrolyte 30 supplied to the main body 21 of the injection mechanism 20 can flow into the battery case 17. If a valve is attached to the outlet 22, this refers to opening the valve so that the electrolyte 30 can flow from the injection mechanism 20 into the battery case 17. Filling the battery case 17 with the electrolyte 30 refers to a state in which no more electrolyte 30 can be injected into the battery case 17 from the injection port 18 and the electrolyte 30 overflows from the battery case 17 when an attempt is made to inject the electrolyte 30. Therefore, when the electrolyte 30 is injected from the injection mechanism 20 into the battery case 17 and the battery case 17 is filled with the electrolyte 30 (above [i]), the excess electrolyte 31 that was not injected into the battery case 17 is stored and held in the main body 21 of the injection mechanism 20 (above [ii]) (Figures 1 and 2).

[0019] When the battery case 17 is filled with the electrolyte solution 30, the entire electrode assembly 1 is immersed in the electrolyte solution 30 (FIGS. 1 and 2). Because the electrode assembly 1 has a positive electrode, a negative electrode, and a separator 10 densely stacked, the electrolyte solution 30 does not easily penetrate into the electrode assembly 1 immediately after immersion in the electrolyte solution 30. However, if the electrode assembly 1 is maintained in a state immersed in the electrolyte solution 30, the electrolyte solution 30 penetrates into the electrode assembly 1 over time. Therefore, even if the battery case 17 is filled with the electrolyte solution 30, the electrolyte solution 30 penetrates into the electrode assembly 1, causing the liquid level of the electrolyte solution 30 in the battery case 17 to drop, resulting in the battery case 17 not being filled with the electrolyte solution 30. In this state, a portion of the electrode assembly 1 is located above the liquid level of the electrolyte solution 30, and the electrode assembly 1 is not entirely immersed in the electrolyte solution 30, thereby reducing the impregnation of the electrode assembly 1 with the electrolyte solution 30.

[0020] In this method, as described above, while the electrolyte solution 30 is being injected into the battery case 17 from the injection mechanism 20, excess electrolyte solution 31 is stored and held in the main body 21 of the injection mechanism 20. At this time, the liquid level of the electrolyte solution 30 (excess electrolyte solution 31) held in the injection mechanism 20 is higher in the direction of gravity than the liquid level in the battery case 17 (FIGS. 1 and 2). In this state, when the liquid level of the electrolyte solution 30 in the battery case 17 drops as the electrode body 1 is impregnated with the electrolyte solution 30, the excess electrolyte solution 31 can be automatically injected into the battery case 17 from the injection mechanism 20. As a result, the battery case 17 is maintained in a state filled with the electrolyte solution 30. Therefore, even if the impregnation of the electrode body 1 with the electrolyte solution 30 progresses, the entire electrode body 1 can be maintained in a state immersed in the electrolyte solution 30, and a decrease in the impregnation of the electrode body 1 with the electrolyte solution 30 can be suppressed.

[0021] The electrode body 1 may have a rectangular shape when viewed from the stacking direction of the positive electrode, negative electrode, and separator 10 (Y direction in FIGS. 1 and 2). When the electrode body 1 is rectangular, the length of the positive electrode active material layer of the positive electrode or the negative electrode active material layer of the negative electrode in the direction parallel to the long side of the rectangle (X direction in FIGS. 1 and 2) is preferably 150 mm or more, and may be 150 mm or more and 500 mm or less, 250 mm or more and 450 mm or less, or 280 mm or more and 400 mm or less. In an electrode body 1 in which the length of the positive electrode active material or the negative electrode active material is within the above range, the impregnation distance when the electrolyte solution 30 is impregnated from the edge to the center of the electrode body 1 is large, and therefore it takes time for the electrolyte solution 30 to impregnate the entire electrode body 1. According to this method, the entire electrode body 1 can be kept impregnated with the electrolyte 30, so that even if the electrode body 1 has a large impregnation distance with the electrolyte 30, it is easy to impregnate the center of the electrode body 1 with the electrolyte 30.

[0022] The liquid inlet 18 is preferably formed on at least one wall surface (wall surface parallel to the Z direction in FIGS. 1 and 2 ) of the battery case 17 that intersects with the long sides of the electrode body 1 when extended. This allows the electrolyte solution 30 to be poured in a direction (a direction parallel to the long sides of the electrode body 1 (X direction)) in which it is difficult to impregnate the center with the electrolyte solution 30 due to a large impregnation distance, thereby improving the impregnation of the electrolyte solution 30 in a direction parallel to the long sides of the electrode body 1. Preferably, the liquid inlet 18 is formed on one wall surface, and there is also one liquid inlet 18 formed on that wall surface.

[0023] As described above, the first layer 15 is partially present and partially absent on the surface of the separator 10 of the electrode assembly 1 of this battery (FIGS. 3 and 4). Therefore, in a cross section of the separator 10, the surface of the separator 10 has a protruding region where the first layer 15 is present and a recessed region where the first layer 15 is not present, as shown in FIGS. 3 and 4. As a result, in an electrode assembly 1 in which a positive electrode, a negative electrode, and a separator 10 are laminated, gaps are likely to form between the separator 10 and the positive electrode and / or negative electrode in the region where the first layer 15 of the separator 10 is not present. The electrolyte solution 30 can easily enter these gaps, thereby improving the impregnation of the electrolyte solution 30 into the electrode assembly 1. Gas generated during the injection of the electrolyte solution 30 can also easily enter these gaps, thereby improving the defoaming of the gas. As described above, in this method, even if the impregnation of the electrode body 1 with the electrolyte solution 30 progresses, the entire electrode body 1 can be maintained immersed in the electrolyte solution 30, and gaps can be formed between the separator 10 and the positive electrode and / or negative electrode into which the electrolyte solution 30 and gas can enter, thereby improving the impregnation of the electrolyte solution 30 and also improving the defoaming of gas.

[0024] The first layers 15 may be present in a striped or dotted pattern on the surface of the separator 10. The presence of the first layers 15 in a striped or dotted pattern allows the formation of flow paths through which the electrolyte solution and gas flow in the regions where the first layers 15 are not present, which facilitates the improvement of electrolyte solution impregnation and gas defoaming. The first layers 15 are preferably present in a striped pattern. This allows linear formation of regions (flow paths) on the surface of the separator 10 where the first layers 15 are not present, which facilitates the flow of the electrolyte solution and gas, which facilitates the improvement of electrolyte solution impregnation and / or gas defoaming. The electrolyte solution that has permeated into the regions where the first layers 15 are not present also permeates from these regions into the regions where the first layers 15 are present, which facilitates the improvement of electrolyte solution impregnation.

[0025] When the electrode assembly 1 is a laminated electrode assembly and the first layer 15 is present on the surface of the separator 10 in a striped pattern, the extension direction of the stripes is preferably parallel to or perpendicular to the wall surface of the battery case 17 on which the inlet 18 is formed. For example, when the inlet 18 is formed at the position shown in FIGS. 1 and 2, the first layer 15 present on the separator 10 of the electrode assembly 1 is preferably formed in a striped pattern extending in the X or Z direction. In a laminated electrode assembly, the electrolyte solution 30 typically penetrates into the electrode assembly 1 from either end in a plan view from the stacking direction (the Y direction in FIGS. 1 and 2). Therefore, when the extension direction of the stripes is parallel to or perpendicular to the wall surface on which the inlet 18 is formed, a region (flow path) on the surface of the separator 10 on which the first layer 15 is not present can be arranged in the direction in which the electrolyte solution 30 is poured from the inlet 18 or in a direction perpendicular thereto. This allows the electrolyte solution 30 injected into the battery case 17 to easily permeate into the region of the electrode body 1 where the first layer 15 is not present. The electrolyte solution that has permeated into the region where the first layer 15 is not present also permeates into the region where the first layer 15 is present, which makes it easier to improve the impregnation of the electrode body 1 with the electrolyte solution 30.

[0026] When the electrode assembly 1 is a laminated electrode assembly, the extension direction of the stripes of the first layer 15 is preferably a direction perpendicular to the wall surface of the battery case 17 on which the liquid inlet 18 is formed. That is, when the liquid inlet 18 is formed at the position shown in FIGS. 1 and 2 , the first layer 15 is preferably formed in stripes extending in the X direction. When the electrode assembly 1 is a wound electrode assembly, the extension direction of the stripes is preferably a direction parallel to the winding axis and perpendicular to the wall surface on which the liquid inlet 18 is formed. In a wound electrode assembly, the electrolyte solution 30 permeates into the electrode assembly 1 from both ends of the winding axis. As a result, a region (flow path) in the separator 10 where the first layer 15 is not present is arranged in the direction in which the electrolyte solution 30 is poured from the liquid inlet 18, and therefore the electrolyte solution 30 poured from the liquid inlet 18 easily permeates into the region where the first layer 15 is not present.

[0027] While Fig. 3 shows a case where separator 10 has functional layers 12 (first layers 15) on both sides, separator 10 may have functional layers 12 on only one side. When separator 10 has functional layers on both sides, first layers 15 on the first side may be formed in areas on the second side corresponding to areas where first layers 15 are not present (Fig. 3), or may be formed in areas on the second side corresponding to areas where first layers 15 are present. As shown in Fig. 3, by arranging first layers 15 on the first side and first layers 15 on the second side alternately on substrate 11 in the cross section of separator 10, electrolyte solution 30 can easily permeate the entire separator 10.

[0028] The functional layer 12 of the separator 10 may have a second layer 16 between the substrate 11 and the first layer 15. The second layer 16 may have an area that is not covered by the first layer. For example, as shown in FIG. 4, a method for providing the second layer 16 with an area that is not covered by the first layer is to form the second layer 16 so as to entirely cover one or both sides of the substrate 11, and form the first layer 15 so as to partially cover the second layer 16. Alternatively, both the first layer 15 and the second layer 16 may be formed partially (e.g., in a striped or dotted pattern) on the substrate 11, and the first layer 15 may be formed on the partially formed second layer 16. Even when the functional layer 12 has the first layer 15 and the second layer 16, the partial presence of the first layer 15 on the surface of the separator 10 can improve the impregnation of the electrolyte and the defoaming of gas.

[0029] The functional layer 12 only needs to include the first layer 15, and may also include a third layer other than the first layer 15 and the second layer 16. The third layer may be formed between the first layer 15 and the second layer 16, or may be formed between the second layer 16 and the substrate 11.

[0030] The functional layer 12 may be formed on only one side or on both sides of the substrate 11. When the functional layer 12 is formed on both sides of the substrate 11, the layer structures of the functional layers 12 on both sides may be the same or different from each other, and the pattern shapes of each layer (e.g., first layer, second layer) constituting the functional layer 12 may also be the same or different from each other.

[0031] The first layer 15 and the second layer 16 may each independently be an adhesive layer or a layer containing inorganic particles. When the functional layer 12 has the first layer 15 and the second layer 16, for example, the first layer 15 may be an adhesive layer and the second layer may be a layer containing inorganic particles (heat-resistant layer).

[0032] The adhesive layer can be formed using an adhesive. Examples of the adhesive include hot melt adhesives, ultraviolet curing adhesives, and thermosetting adhesives. Examples of the base resin of the adhesive include one or more resins selected from the group consisting of acrylic resins, urethane resins, ethylene vinyl acetate resins, epoxy resins, and fluororesins. The adhesive layer may contain inorganic particles contained in the layer containing inorganic particles.

[0033] The layer containing inorganic particles may contain a binder resin in addition to the inorganic particles. Examples of inorganic particles include ceramic particles selected from the group consisting of alumina, boehmite, aluminum hydroxide, silica, magnesia, titania, silicon nitride, and titanium nitride. Examples of binder resins include acrylic binder resins such as acrylic resins, fluoropolymer binder resins such as polyvinylidene fluoride, and styrene-butadiene rubber (SBR).

[0034] The thickness of the first layer 15 and the second layer 16 may be independently 0.5 μm or more, 0.5 to 6 μm, 1 to 5 μm, or 1 to 4 μm.

[0035] In this method, preferably, after the above steps [i] and [ii], an operation of reducing the pressure inside the battery case 17 containing the electrode assembly 1 and returning it to normal pressure is carried out one or more times. This promotes permeation of the electrolyte solution 30 into the electrode assembly 1 and makes it easier to remove gas from the battery case 17. One method of reducing the pressure inside the battery case 17 is to place the battery case 17 containing the electrode assembly 1 in a chamber container, reduce the pressure inside the chamber container, maintain the reduced pressure, and then return the chamber container to normal pressure. The gauge pressure during the reduced pressure may be, for example, -0.5 to -0.01 MPa or -0.3 to -0.05 MPa. The time for maintaining the reduced pressure is, for example, 0.1 to 10 minutes, 0.5 to 5 minutes, or 1 to 3 minutes. The operation of reducing the pressure and returning it to normal pressure may be carried out one or more times, or may be repeated 2 to 5 times, or may be repeated 2 to 3 times. [Explanation of symbols]

[0036] 1 electrode body, 10 separator, 11 substrate, 12 functional layer, 15 first layer, 16 second layer, 17 battery case, 18 inlet, 20 liquid injection mechanism, 21 main body, 22 outlet, 30 electrolyte, 31 excess electrolyte (electrolyte).

Claims

1. A method for manufacturing a nonaqueous electrolyte secondary battery including a battery case, and an electrode assembly and an electrolyte solution housed in the battery case, the electrode assembly includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; the separator has a porous substrate and a functional layer, the functional layer includes a first layer partially present on at least one surface of the separator, The manufacturing method for a nonaqueous electrolyte secondary battery includes attaching a liquid injection mechanism to the battery case, and in a state in which the electrolyte is injected into the battery case from an injection port of the liquid injection mechanism, [i] injecting the electrolyte from the liquid injection mechanism to fill the battery case with the electrolyte, and [ii] storing and holding surplus electrolyte that has not been injected into the battery case in the liquid injection mechanism.

2. the electrode body has a rectangular shape when viewed from the stacking direction of the positive electrode, the negative electrode, and the separator, 2 . The method for producing a nonaqueous electrolyte secondary battery according to claim 1 , wherein the length of the positive electrode active material layer of the positive electrode or the negative electrode active material layer of the negative electrode in a direction parallel to a long side of the rectangle is 150 mm or more.

3. The method for manufacturing a nonaqueous electrolyte secondary battery according to claim 2 , wherein the liquid injection port is formed in at least one wall surface of the battery case that intersects with the long sides when extended.

4. The method for producing a nonaqueous electrolyte secondary battery according to claim 1 , wherein the first layer is present on the at least one surface in the form of stripes or dots.

5. The electrode body is a laminated electrode body, the first layer is present on the at least one surface in a striped pattern, 3. The method for manufacturing a nonaqueous electrolyte secondary battery according to claim 1, wherein the extending direction of the stripes of the first layer is parallel to or perpendicular to a wall surface of the battery case on which the liquid filling port is formed.

6. 3. The method for producing a nonaqueous electrolyte secondary battery according to claim 1, wherein after the steps [i] and [ii], an operation of reducing the pressure inside the battery case accommodating the electrode assembly and returning it to normal pressure is carried out one or more times.

7. the first layer is partially present on each of the first and second surfaces of the separator, The method for manufacturing a nonaqueous electrolyte secondary battery according to claim 1 , wherein the first layer on the first surface is present in a region corresponding to a region on the second surface where the first layer is not present.

8. 3. The method for producing a nonaqueous electrolyte secondary battery according to claim 1, wherein the first layer has a thickness of 0.5 [mu]m or more.

9. 3. The method for producing a nonaqueous electrolyte secondary battery according to claim 1, wherein the first layer is an adhesive layer or a layer containing inorganic particles.

10. the functional layer has a second layer between the first layer and the substrate, 3. The method for producing a nonaqueous electrolyte secondary battery according to claim 1, wherein the second layer has a region that is not covered by the first layer.

11. The method for producing a nonaqueous electrolyte secondary battery according to claim 10 , wherein the second layer covers the entire surface of the substrate on the side of the separator where the first layer is present.

12. The method for producing a nonaqueous electrolyte secondary battery according to claim 10 , wherein the second layer is an adhesive layer or a layer containing inorganic particles.

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