Non-aqueous electrolyte secondary battery and method for manufacturing non-aqueous electrolyte secondary battery

Abstract

A lithium ion secondary battery has an electrode body, a nonaqueous electrolyte, and a rectangular battery case that houses the electrode body and the nonaqueous electrolyte, in the electrode body, a positive electrode including a positive electrode substrate and a positive electrode composite material layer and a negative electrode including a negative electrode substrate and a negative electrode composite material layer are laminated with a separator made of a porous resin interposed therebetween and are wound to be flat, when a spring constant of the lithium ion secondary battery under a load of 316 to 210 N / cm 2 is assumed to be spring constant H, and when a spring constant of the lithium ion secondary battery under a load of 95 to 74 N / cm 2 is assumed to be spring constant L, a ratio L / H of the spring constant L to the spring constant H is 0.34 ≤ L / H ≤ 0.41, and an electrical resistance increase rate before and after a rectangular wave test is 1.17 or less.

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing non-aqueous electrolyte secondary batteries and non-aqueous electrolyte secondary batteries. More specifically, it relates to a method for manufacturing non-aqueous electrolyte secondary batteries with low rate aging. Background Technology

[0002] In recent years, for non-aqueous electrolyte secondary batteries such as lithium-ion batteries, in order to use them as power sources for electric vehicles, they are constructed by connecting a large number of cell units in series / parallel and supplying them with high voltage / high current. Therefore, to accommodate a large number of cell units, wound-type batteries, which are formed by winding electrode plates, are used. In addition, to improve compactness and cooling efficiency, cell units with flat wound electrode bodies are often used.

[0003] In a flat, wound electrode body, the active material layer expands / contracts during charging and discharging. This causes an increase or decrease in pressure within the electrode body. Consequently, the concentration of supporting salts may become uneven, or non-aqueous electrolytes may leak out of the electrode body, leading to electrolyte desiccation. As a result, the internal resistance of the secondary battery may increase. Especially in secondary batteries used with repeated high-rate charge-discharge cycles, so-called high-rate aging can develop rapidly.

[0004] Therefore, for example, the following invention is disclosed in Japanese Patent Application Publication No. 2018-106981. The spring constant of the outer circumferential portion is greater than that of the inner circumferential portion. This suppresses the expansion of the electrode body and inhibits high-rate aging. In the central region of the negative electrode, where the movement of non-aqueous electrolyte is prone to occur, by making the spring constant of the outer circumferential portion greater than that of the inner circumferential portion, the outer circumferential portion becomes harder and less prone to stretching. Therefore, the thickness change during charging and discharging can be suppressed in the outer circumferential portion. As a result, the extrusion of non-aqueous electrolyte from the winding termination portion of the electrode body can be appropriately suppressed. Summary of the Invention

[0005] However, in the invention disclosed in Japanese Patent Application Publication No. 2018-106981, in order to change the spring constant on the inner and outer circumferences of the winding, it is necessary to change the electrode composition and composite material density in the length direction of the electrode body, which leads to the problem of the electrode body becoming more complex. In addition, the manufacturing process also becomes more complex.

[0006] The problem to be solved by the non-aqueous electrolyte secondary battery and the manufacturing method of the non-aqueous electrolyte secondary battery disclosed herein is that the electrode body is not complicated and degradation can be reduced even when used in a manner of repeated high-rate charge and discharge.

[0007] One aspect of this disclosure is a non-aqueous electrolyte secondary battery, comprising an electrode body, a non-aqueous electrolyte, and a cuboid battery case housing the electrode body and the non-aqueous electrolyte. The non-aqueous electrolyte secondary battery is characterized in that, in the electrode body, a positive electrode comprising a positive electrode substrate and a positive electrode composite material layer, and a negative electrode comprising a negative electrode substrate and a negative electrode composite material layer, are laminated and wound together with a separator made of porous resin, forming a flat shape. The non-aqueous electrolyte secondary battery is designed to operate at 316–210 N / cm². 2 The spring constant under load is H. Assume the non-aqueous electrolyte secondary battery operates at 95–74 N / cm. 2 When the spring constant under the load is the spring constant L, the ratio of the spring constant L to the spring constant H, L / H, is 0.34≤L / H≤0.41.

[0008] The aforementioned non-aqueous electrolyte secondary battery can be a lithium-ion secondary battery.

[0009] Furthermore, another aspect of the present disclosure is a method for manufacturing a non-aqueous electrolyte secondary battery, which includes an electrode body, a non-aqueous electrolyte, and a cuboid battery case housing the electrode body and the non-aqueous electrolyte. The method for manufacturing the non-aqueous electrolyte secondary battery is characterized in that, only when the non-aqueous electrolyte secondary battery is at room temperature of 10 to 35°C, the electrode body is directly or indirectly pressurized and constrained in the thickness direction.

[0010] Furthermore, the manufacturing method of the aforementioned non-aqueous electrolyte secondary battery includes the following steps: a winding step, in which a positive electrode comprising a positive electrode substrate and a positive electrode composite material layer and a negative electrode comprising a negative electrode substrate and a negative electrode composite material layer are laminated and wound together with a separator made of porous resin in between; a winding pressing step, in which the wound electrode body is pressed into a flat shape; a battery cell drying step, in which the electrode body is dried inside the battery casing; an initial charging step; an aging step; and an inspection step, wherein the aforementioned constraint is performed in at least one of the aforementioned initial charging step and the aforementioned inspection step, but not in the aforementioned battery cell drying step and the aforementioned aging step.

[0011] Furthermore, in the above-mentioned method for manufacturing a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery is assumed to have a strength of 316–210 N / cm. 2 The spring constant under load is H. Assume the non-aqueous electrolyte secondary battery operates at 95–74 N / cm. 2 When the spring constant under load is the spring constant L, the above constraint conditions can be set according to the ratio L / H of the spring constant L to the spring constant H as a preset setting value.

[0012] Furthermore, in the above-mentioned method for manufacturing non-aqueous electrolyte secondary batteries, the above-mentioned constraint conditions can also be set in such a way that the ratio L / H is 0.34≤L / H≤0.41.

[0013] In the above-mentioned method for manufacturing a non-aqueous electrolyte secondary battery, the pressure applied during the constraint can be 210 N / cm. 2 Perform under the following load range.

[0014] The aforementioned non-aqueous electrolyte secondary battery can be a lithium-ion secondary battery.

[0015] The manufacturing method of the non-aqueous electrolyte secondary battery disclosed herein does not complicate the electrode body, and can reduce degradation even when used in a manner involving repeated high-rate charge and discharge. Attached Figure Description

[0016] Figure 1 This is a perspective view of the lithium-ion secondary battery according to this embodiment.

[0017] Figure 2 This is a schematic diagram showing the structure of the laminated electrode body of a lithium-ion secondary battery.

[0018] Figure 3 This is a schematic diagram showing the structure of the laminated electrode body of a lithium-ion secondary battery.

[0019] Figure 4 This is a schematic diagram showing the configuration of the end of the electrode body as viewed from the width direction W.

[0020] Figure 5 This is a flowchart illustrating the manufacturing process of the lithium-ion secondary battery according to this embodiment.

[0021] Figure 6 This is a flowchart illustrating process A for adjusting the spring constant in this embodiment.

[0022] Figure 7 This is a table showing the test conditions for the embodiments and comparative examples of this implementation.

[0023] Figure 8 This is a diagram showing a rectangular wave test used to test the high-rate aging of the lithium-ion secondary battery of this embodiment.

[0024] Figure 9 This is a table showing the test results of the embodiments and comparative examples of this implementation.

[0025] Figure 10 This is a diagram illustrating the test results of embodiments and comparative examples of this implementation. Detailed Implementation

[0026] Reference Figures 1-10 The manufacturing method of the non-aqueous electrolyte secondary battery and the non-aqueous electrolyte secondary battery of this disclosure will be described using one embodiment of the lithium-ion secondary battery 1 and its manufacturing method as an example.

[0027] (Structure of the first embodiment)

[0028] <Principle of this implementation method>

[0029] The lithium-ion secondary battery 1 and its manufacturing method according to this embodiment do not complicate the electrode body 10, and can reduce degradation even when used in a manner that involves repeated high-rate charging and discharging.

[0030] During repeated high-rate charge and discharge cycles, the active material layer in the flat, wound electrode body 10 expands / contracts with each charge and discharge. This causes an increase or decrease in pressure within the electrode body 10. Consequently, the concentration of the supporting salt may become uneven, or the non-aqueous electrolyte 17 may leak out of the electrode body 10, resulting in electrolyte desiccation. As a result, the internal resistance of the lithium-ion secondary battery 1 may increase. This performance degradation caused by such reasons is referred to as high-rate aging.

[0031] Therefore, in the lithium-ion secondary battery 1 and its manufacturing method of this embodiment, by suppressing high-rate aging, the uneven distribution of the supporting salt concentration can be suppressed, and the electrolyte drying caused by the non-aqueous electrolyte flowing out to the outside of the electrode body 10 can be suppressed. Therefore, the pressure rise and fall inside the electrode body 10 can be suppressed.

[0032] Specifically, under high load and high SOC conditions, the electrode body 10 expands. In this state, by making the electrode body 10 flexible, it can absorb volume changes, preventing the electrolyte from being discharged during expansion. Thus, the electrolyte's liquid retention capacity under high SOC conditions can be maintained at a high level.

[0033] On the other hand, under low load and low SOC conditions, the electrode body 10 shrinks. In this state, by hardening the electrode body 10, volume change can be suppressed, preventing the electrolyte from being discharged during shrinkage. Thus, even under low SOC conditions, the electrolyte retention capacity can be maintained at a high level.

[0034] By taking both aspects into account, it is possible to produce lithium-ion rechargeable batteries with high rate of operation and low aging.

[0035] Therefore, regarding the hardness of the electrode body 10, the inventors have determined the hardness of the electrode body 10 during expansion and the hardness of the electrode body 10 during contraction. Furthermore, the hardness of the electrode body 10 as a lithium-ion secondary battery is 316–210 N / cm. 2The spring constant under load is set as H, and the load is 95–74 N / cm. 2 The spring constant under load is denoted as spring constant L. In one example, "spring constant H" is the value of 316–210 N / cm² applied to the lithium-ion secondary battery along the thickness direction D. 2 The spring constant of a lithium-ion secondary battery under load, where "spring constant L" is the value of the lithium-ion secondary battery under a load of 95–74 N / cm² in the thickness direction D. 2 The spring constant of the lithium-ion secondary battery under load. Here, by measuring the spring constant H and spring constant L after the lithium-ion secondary battery is assembled, the hardness of the electrode body 10 can be indirectly measured through the battery casing 11. Furthermore, the inventors have discovered through experiments that when the ratio of spring constant L to spring constant H, L / H, is 0.34 ≤ L / H ≤ 0.41, the balance is good and high-rate aging is minimal.

[0036] Furthermore, the inventors discovered that, to achieve this, by directly or indirectly constraining the electrode body 10 only in the room temperature process, i.e., by directly or indirectly constraining the electrode body 10 only in the room temperature process and not constraining the electrode body 10 in the low temperature and high temperature processes, the spring constant L on the low load side specifically increases. A manufacturing method was discovered that utilizes this characteristic to achieve a spring constant L / H ratio L / H of 0.34 ≤ L / H ≤ 0.41. In the manufacturing method of the non-aqueous electrolyte secondary battery 1 comprising the electrode body 10, the non-aqueous electrolyte 17, and the cuboid battery case 11 housing the electrode body 10 and the non-aqueous electrolyte 17, pressure is applied directly or indirectly in the thickness direction only in the room temperature manufacturing process (room temperature process) where the temperature of the non-aqueous electrolyte secondary battery 1 is 10–35°C in a plurality of manufacturing steps, under specific conditions. That is, in the low temperature and high temperature processes in a plurality of manufacturing steps, no direct or indirect constraint is applied to the electrode body 10 in the thickness direction.

[0037] <Composition of Lithium-ion Secondary Battery 1>

[0038] First, a brief explanation of the structure of the lithium-ion secondary battery 1, which is the premise of this embodiment, will be given.

[0039] Figure 1 This is a 3D diagram of lithium-ion secondary battery 1. (See diagram below.) Figure 1As shown, the lithium-ion secondary battery 1 is configured as a single-cell battery. The lithium-ion secondary battery 1 includes a cuboid battery case 11 with an opening on its upper side. The battery case 11 has a cover 12 that seals the battery case 11. Electrode bodies 10 are housed inside the battery case 11. A non-aqueous electrolyte 17 is injected into the battery case 11 through an injection hole (not shown). The battery case 11 and the cover 12 are made of a metal such as aluminum alloy. In the lithium-ion secondary battery 1, a sealed battery cell is formed by mounting the cover 12 to the battery case 11. Furthermore, in the lithium-ion secondary battery 1, the cover 12 has a negative external terminal 14 and a positive external terminal 16 for charging and discharging.

[0040] <Electrode 10>

[0041] Figure 2 This is a schematic diagram showing the structure of the laminated electrode body 10 of the lithium-ion secondary battery 1. (See diagram below.) Figure 2 As shown, the electrode body 10 of the lithium-ion secondary battery 1 includes a negative electrode plate 100, a positive electrode plate 110, and a separator 120. The negative electrode plate 100 has a negative electrode composite material layer 102 on both sides of the negative electrode substrate 101. The positive electrode plate 110 has a positive electrode composite material layer 112 on both sides of the positive electrode substrate 111. The negative electrode plate 100 and the positive electrode plate 110 are overlapped and laminated with the separator 120 in between to form a laminate. This laminate is wound along the length direction Z with a winding axis as the center and shaped into a flat shape to form the electrode body 10.

[0042] The negative electrode connection 103 functions as a current collector for extracting power from the negative electrode composite material layer 102 of the negative electrode plate 100. The positive electrode connection 113 functions as a current collector for extracting power from the positive electrode composite material layer 112 of the positive electrode plate 110.

[0043] <End configuration of electrode body 10>

[0044] Figure 3 This is a perspective view showing the negative electrode side end of the wound electrode body 10 in the width direction. The electrode body 10 is wound around a portion supporting a center CC centered on a winding axis. Figure 5 (S3). Next, from the thickness direction D, which is orthogonal to the width direction W, a pair of opposing presses 2 (see reference) are used. Figure 4 Through the winding and pressing process ( Figure 5 S4) The shape is flattened at the end when viewed from the width direction W, for example, a flattened shape like a racetrack. Then, as... Figure 1The flat electrode body 10 is housed in the battery casing 11, and the negative current collector 13 is welded to the negative connection portion 103. The positive current collector 15 is welded to the positive connection portion 113. Welding methods for the connection portion and the current collector include, for example, ultrasonic welding, resistance welding, and electric welding. Then, the negative external terminal 14 is connected to the negative current collector 13 through the cover 12, and the positive external terminal 16 is connected to the positive current collector 15.

[0045] Here, the direction of the electrode body 10 parallel to the winding axis is referred to as the "width direction W". Furthermore, the direction of the electrode body 10 orthogonal to the winding axis and the surface of the flat portion F is referred to as the "thickness direction D". Additionally, the direction orthogonal to both the width direction W and the thickness direction D is referred to as the "length direction Z".

[0046] <F flat section and R curved section>

[0047] Figure 4 This is a schematic diagram showing the configuration of the end of the electrode body 10 as viewed from the width direction W. The central part of the electrode body 10, which is pressed into a flat shape, is straight, and a planar "flat part F" is formed by the negative electrode plate 100, the positive electrode plate 110 and the spacer 120.

[0048] In addition, at the upper and lower ends of the flat portion F, the electrode body 10, which is composed of a laminated negative electrode plate 100, a positive electrode plate 110, and a separator 120, is bent into a semi-cylindrical shape to form a bent portion R.

[0049] The curved portion R, when viewed from the width direction W, is approximately a concentric semicircle. That is, the negative electrode plate 100, positive electrode plate 110, and separator 120, which are laminated in the curved portion R, are approximately concentric semicircles when viewed from the width direction W. The position that will become the center of these semicircles is referred to as "center C". This center C can be considered as a straight line continuing along the width direction W. In addition, "center C" can also be said to be the midpoint of the boundary line between the flat portion F and the curved portion R in the length direction Z.

[0050] <Negative electrode plate 100>

[0051] A negative electrode composite material layer 102 is formed on both sides of the negative electrode substrate 101 to form a negative electrode plate 100. In this embodiment, the negative electrode substrate 101 is made of Cu foil. The negative electrode substrate 101 forms a base that serves as the aggregate for the negative electrode composite material layer 102 and functions as a current collector that collects electricity from the negative electrode composite material layer 102. The negative electrode plate 100 has the negative electrode composite material layer 102 formed on the metal-made negative electrode substrate 101. In the first embodiment, the negative electrode active material is a material capable of intercalating / deintercalating lithium ions, and a powdered carbon material such as graphite is used.

[0052] The negative electrode plate 100 is manufactured, for example, by mixing the negative electrode active material, solvent and adhesive (binder), coating the mixed negative electrode composite material onto the negative electrode substrate 101 and drying it.

[0053] <Positive Plate 110>

[0054] A positive electrode composite material layer 112 is formed on both sides of the positive electrode substrate 111 to form a positive electrode plate 110. In this embodiment, the positive electrode substrate 111 is made of Al foil or Al alloy foil. The positive electrode substrate 111 serves as a base that acts as the aggregate for the positive electrode composite material layer 112 and functions as a current collector that collects electricity from the positive electrode composite material layer 112.

[0055] In the positive electrode plate 110, a positive electrode composite material layer 112 is formed on the surface of the positive electrode substrate 111. The positive electrode composite material layer 112 has a positive electrode active material. The positive electrode active material is a material capable of lithium intercalation / deintercalation, and can be, for example, lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), etc. Alternatively, a material formed by mixing LiCoO2, LiMn2O4, and LiNiO2 in any proportion can also be used.

[0056] In addition, the positive electrode composite layer 112 contains a conductive material. As a conductive material, carbon black such as acetylene black (AB), Ketjen black, or graphite can be used.

[0057] The positive electrode plate 110 is manufactured, for example, by mixing positive electrode active material, conductive material, solvent and adhesive (binder), coating the mixed positive electrode composite material onto positive electrode substrate 111 and drying it.

[0058] <Separator 120>

[0059] The separator 120 is a nonwoven fabric made of porous resin such as polypropylene, used to hold the non-aqueous electrolyte 17 between the negative electrode plate 100 and the positive electrode plate 110. Alternatively, the separator 120 can be a porous polymer membrane such as a porous polyethylene membrane, a porous polyolefin membrane, or a porous polyvinyl chloride membrane, or a lithium-ion or ion-conductive polymer electrolyte membrane, used alone or in combination. When the electrode body 10 is immersed in the non-aqueous electrolyte 17, the non-aqueous electrolyte permeates from the ends of the separator 120 toward the center.

[0060] <Mechanical properties of spacer 120>

[0061] Regarding the structure of the spacer 120, it is a porous structure as a whole, with a relatively coarse skeleton portion and a relatively fine three-dimensional mesh-like portion formed in the skeleton portion. Then, in the winding pressing process (S4), when the spacer 120 is compressed, due to the elasticity of the resin in the spacer 120, the spacer 120 undergoes elastic deformation, causing the porous portion to be flattened. At this time, even when the same force is applied, the finer three-dimensional mesh-like portion formed in the skeleton portion undergoes greater deformation compared to the coarser skeleton portion. When the spacer 120 is returned to a free state without applied force, its thickness as a whole is approximately restored under elastic restoring force. At this time, the finer three-dimensional mesh-like portion, which has undergone greater deformation, has portions that undergo plastic deformation exceeding the yield point. In contrast, the coarser skeleton portion is less prone to plastic deformation and approximately restores its original shape under elastic restoring force. The spacer 120 hardens when compressed in this way, and the spring constant increases.

[0062] <Plastic deformation depending on the temperature of the spacer 120>

[0063] The spacer 120 is relatively difficult to undergo plastic deformation at room temperature (10-35℃), but it is relatively easy to undergo plastic deformation at high temperature (above 35℃).

[0064] Whether it is at room temperature can be determined by the temperature of the operating environment. Alternatively, it can be due to temperature changes caused by the battery itself generating or releasing heat. Furthermore, it can be due to temperature changes caused by external heating or cooling. In short, whether the separator 120 is prone to plastic deformation or not becomes a problem.

[0065] <Change in spring constant due to compression of spacer 120>

[0066] Here, "constraint" refers to applying pressure to the electrode body 10 directly or indirectly along the thickness direction D, thereby compressing the separator 120. During pressure application, the electrode body 10 can be directly compressed using a pressing device or similar means. Alternatively, after the electrode body 10 is housed in the battery casing 11, it can be compressed by pressing the battery casing 11 along the thickness direction D. Furthermore, the battery casing 11 can be pressed along the thickness direction D while multiple cell units are stacked. The pressing is not limited to the press 2; it can also be implemented using a constraint frame with threaded fastening.

[0067] When the electrode body 10 is compressed at high temperature, the softened septum 120 is also compressed, undergoing plastic deformation and hardening in a way that the gap portion is flattened. That is, the spring constant increases.

[0068] On the other hand, when the electrode body 10 is compressed at room temperature, the unsoftened septum 120 undergoes plastic deformation and hardening in the manner of flattening the void portion, but the degree is smaller compared to high temperature. That is, the increase in spring constant is smaller.

[0069] <Spring constant H and spring constant L>

[0070] Therefore, the inventors will use a secondary battery with a strength of 316–210 N / cm. 2 The spring constant under load is set as "spring constant H", and the spring constant of the secondary battery is 95-74 N / cm. 2 The spring constant under load is defined as "spring constant L," which determines the stiffness of electrode 10 (secondary cell) during expansion and contraction. In one example, "spring constant H" is defined as 316–210 N / cm² applied to the secondary cell in the thickness direction D. 2 The spring constant of the secondary battery under load, "spring constant L" is the value of the secondary battery under a thickness direction D when 95-74 N / cm is applied. 2 The spring constant of the secondary battery under load. In this case, by measuring the "spring constant H" and the "spring constant L", the hardness of the electrode body 10 under expansion and the hardness of the electrode body 10 under contraction can be indirectly determined.

[0071] Here, the spring constant can be measured by pressing the portion of the secondary battery corresponding to the electrode body 10 through the battery casing 11 with a specific pressure at room temperature (10-35°C).

[0072] The "spring constant H" represents the behavior under a large force. Specifically, it refers to the behavior of the electrode body 10 when it expands under high load and high SOC. In this state, by reducing the "spring constant H," i.e., by making the electrode body 10 more flexible, it can absorb volume changes, preventing the electrolyte from being discharged during expansion. Thus, the electrolyte's liquid retention capacity can be maintained at a high level under high SOC conditions.

[0073] The "spring constant L" represents the behavior under a small force. Specifically, it represents the contraction behavior of the electrode body 10 under low load and low SOC conditions. In this state, by increasing the "spring constant L," i.e., stiffening the electrode body 10, volume change can be suppressed, preventing the electrolyte from being discharged during contraction. Thus, even under low SOC conditions, the electrolyte retention capacity can be maintained at a high level.

[0074] <Setting the ratio L / H of the spring constant H to the spring constant L>

[0075] If the electrode body 10 is directly or indirectly constrained at high temperature, both the spring constant H (spring constant of the spacer 120 under high load) and the spring constant L (spring constant of the spacer 120 under low load) will increase.

[0076] On the other hand, if the electrode body 10 is directly or indirectly constrained at room temperature, the spring constant H (the spring constant of the spacer 120 under high load) is not easily changed, only the spring constant L (the spring constant of the spacer 120 under low load) becomes higher. That is, the values ​​of the spring constant H and the spring constant L are close.

[0077] Here, the ratio of the spring constant L to the spring constant H is called "L / H".

[0078] The inventors have discovered that the "L / H ratio" is important in order to maintain high liquid retention under both high and low SOC conditions.

[0079] A situation where the spring constant ratio (L / H) is too small includes cases where the spring constant H is larger than the spring constant L, or cases where the spring constant L is smaller than the spring constant H. In such cases, it is expected that the liquid retention will deteriorate during the expansion and contraction of the electrode body 10, and uneven salt concentration will easily occur.

[0080] On the other hand, a situation where the spring constant ratio (L / H) is too large is, for example, when the spring constant H is smaller than the spring constant L, or when the spring constant L is larger than the spring constant H. In such cases, it is expected that the amount of electrolyte retained during the expansion of the electrode body 10 will be too large, thus contributing to uneven salt concentration; or the electrode body 10 will become too rigid, hindering the discharge and inflow of electrolyte, and easily leading to uneven salt concentration.

[0081] In this embodiment, as described below, the ratio L / H of the spring constant L to the spring constant H is set to 0.34≤L / H≤0.41.

[0082] <Adjustment of spring constant H and spring constant L>

[0083] In the spacer 120 made of porous resin, the finer three-dimensional mesh-like portion before the winding body pressing process (S4) undergoes plastic deformation in the winding body pressing process (S4) due to deformation exceeding the yield point, resulting in a smaller void diameter compared to before the winding body pressing process. That is, the "spring constant" of the spacer 120 changes before and after the winding body pressing process (S4). As described above, the overall size of the spacer 120 does not change significantly before and after the winding body pressing process (S4) due to the restoring force of the skeleton portion. However, even if the overall size is restored, the spring constant changes significantly as the voids are flattened and reduced. It should be noted that the winding body pressing process (S4) is carried out at room temperature, where plastic deformation is relatively difficult to occur, thus maintaining the softness of the spacer 120.

[0084] On the other hand, since the drying process (S8) and aging process (S11) of the battery cell are both carried out at high temperature, when the cell cell is constrained in these processes, that is, when the electrode body 10 is indirectly constrained, the softened separator 120 undergoes significant plastic deformation, and changes significantly in the manner that both the spring constant H (spring constant of the electrode body 10 under high load) and the spring constant L (spring constant of the electrode body 10 under low load) increase.

[0085] In addition, the initial charging process (S10), self-discharge inspection process (S12), and shipment inspection process (S13) are all carried out at room temperature. Therefore, even if the cell or battery stack is constrained in these processes, that is, the electrode body 10 is indirectly constrained, the plastic deformation of the separator 120 is small, and it changes in a way that only the spring constant L (the spring constant of the electrode body 10 under low load) increases.

[0086] That is, by applying a "constraint" at "normal temperature", only the "spring constant L" can be adjusted. As a result, the ratio L / H of the spring constant H to the spring constant L can be adjusted to the set value.

[0087] <Non-aqueous electrolyte 17>

[0088] A non-aqueous electrolyte is a composition containing a supporting salt in a non-aqueous solvent. Here, ethylene carbonate (EC) can be used as the non-aqueous solvent. Alternatively, the non-aqueous solvent can be one or more materials selected from the group consisting of propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). Furthermore, the supporting salt can be LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC4F9SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiI, etc. Additionally, the supporting salt can be one or more lithium compounds (lithium salts) selected from these.

[0089] <Manufacturing Process of Lithium-ion Secondary Battery 1>

[0090] Figure 5 This is a flowchart illustrating the manufacturing process of the lithium-ion secondary battery 1 according to this embodiment. (Refer to...) Figure 5 A summary of the manufacturing process of the lithium-ion secondary battery 1 according to this embodiment will be described.

[0091] <Initial Process (Source Project) (S1)>

[0092] In this embodiment, an initial process (S1) is performed first. Here, the initial process is the manufacturing process of the battery elements of the lithium-ion secondary battery 1. Specifically, it is the process of manufacturing the negative electrode plate 100, the positive electrode plate 110, and the separator 120 that constitute the battery elements of the lithium-ion secondary battery 1.

[0093] <Lamination Process (S2)>

[0094] In the initial process (S1), the negative electrode plate 100, the positive electrode plate 110 and the separator 120 are fabricated respectively, and then the lamination process (S2) is performed.

[0095] like Figure 2 As shown, in the lamination process, the negative electrode plate 100, separator 120, positive electrode plate 110, and separator 120 are laminated in that order. At this time, the negative electrode composite material layer 102 and the positive electrode composite material layer 112 are arranged opposite each other with the separator 120 in between. Furthermore, at one end in the width direction W, the negative electrode connection portion 103 is arranged to protrude from the separator 120. At the other end, the positive electrode connection portion 113 is arranged to protrude from the separator 120.

[0096] <Winding process (S3)>

[0097] like Figure 2 As shown, in the lamination process (S2), the electrode body 10, which is laminated in the order of negative electrode plate 100, separator 120, positive electrode plate 110, and separator 120, undergoes a winding process (S3). In the winding process (S3), the laminated electrode plate 10 is wound around the winding axis AX in the width direction W, with the core material supporting the center CC as the center.

[0098] Figure 3 , Figure 4 This is a schematic diagram showing the electrode body 10 after the winding process (S3) is completed. Figure 4 As shown, the wound electrode body 10 forms a flat portion F such as a racing track, and curved portions R formed at both ends thereon.

[0099] <Wrapped body pressing process (S4)>

[0100] Figure 4 This is a schematic diagram showing the electrode body 10 in the winding body pressing process (S4). Figure 4 As shown, in the winding process (S3), the electrode body 10 is wound, forming a flat portion F and curved portions R at both ends when viewed from the width direction W. The electrode body 10 is compressed from the thickness direction D by a press 2 having a pressing surface 2a composed of a pair of opposing planes, clamping the flat portion F with a force not exceeding 100 kN. In the winding pressing process (S4), the electrode body 10, after being compressed by the press 2, roughly recovers its shape within a few seconds due to the elastic repulsive force, but the structure of the spacer 120 is flattened and hardened, and the spring constant increases. At this time, the temperature is maintained at 25°C so that the structure of the spacer 120 is not excessively flattened due to the softening of the resin. Furthermore, the pressing time and extrusion pressure can be adjusted by observing changes in the spring constant.

[0101] Terminal soldering process (S5)

[0102] like Figure 2 As shown, in the electrode body 10 which has been shaped by the winding body pressing process (S4), a negative electrode connection portion 103 with the negative electrode substrate 101 exposed is formed at one end, and a positive electrode connection portion 113 with the positive electrode substrate 111 exposed is formed at the other end.

[0103] Therefore, as Figure 3 As shown, in terminal welding (S5), the negative current collector 13 is welded to the negative connection part 103 to make an electrical / mechanical connection.

[0104] In addition, such as Figure 1 As shown, the positive current collector 15 is also welded to the positive connection part 113 for electrical / mechanical connection.

[0105] <Shell insertion process (S6)>

[0106] After that, as Figure 1 As shown, the flattened electrode body 10, the positive current collector 15 and the negative current collector 13 welded to the electrode body 10 are inserted into the battery case 11 by the case insertion (S6) process.

[0107] <Sealing and Welding Process (S7)>

[0108] In the sealing welding (S7) process, the battery casing 11 and the cover 12 are sealed by laser welding or the like. At this stage, the non-aqueous electrolyte has not yet been injected, and the injection port of the cover 12 is open.

[0109] <Battery cell drying process (S8)>

[0110] In the battery cell drying (S8) process, the temperature inside the battery is raised to, for example, about 105°C in order to thoroughly dry any moisture remaining inside the battery casing. During this process, the resin of the separator 120 softens due to the high temperature, and therefore no restraint is applied.

[0111] <Injection / Sealing Process (S9)>

[0112] In the electrolyte injection / sealing (S9) process, non-aqueous electrolyte 17 is injected into the dry cell through the injection port. After injection, the injection port is sealed. This completes the assembly of the cell unit.

[0113] <Initial charging process (S10)>

[0114] After the cell assembly is completed, an initial charging process (S10) is performed. Furthermore, an initial charge is performed to form an SEI (Solid Electrolyte Interphase) coating, etc. The initial charge is performed at a low charge rate to suppress the temperature rise of the battery. In this embodiment, the initial charge is performed, for example, at approximately 25°C. In this state, the resin constituting the separator 120 does not soften. During the initial charging process (S10), the cell is constrained. The constraining is performed at 10 kN or less. The constraining continues until the initial charging process (S10) is completed. The pressure and time are adjusted while observing the spring constant L.

[0115] <Aging Process (S11)>

[0116] After the initial charging process (S10) is completed, an aging process (S11) is performed. In the aging process (S11), the cell is chemically stabilized / activated. One of its purposes is to eliminate the micro-short circuit caused by a fine metal present in the electrode, where current flows through the metal and generates a high temperature, thereby melting the metal and eliminating the micro-short circuit. Therefore, in the aging process (S11), the temperature is maintained at a high temperature, for example, around 60°C in this embodiment. Therefore, in process A of this embodiment, in the aging process (S11), the resin constituting the separator 120 softens at a high temperature, thereby making the spring constant too high and thus failing to provide restraint.

[0117] <Self-discharge inspection procedure (S12)>

[0118] In the self-discharge inspection process (S12), the lithium-ion secondary battery 1 is fully charged to 100% SOC using the initial charging process (S10). In the aging process (S11), the open-circuit voltage (OCV) after being placed at a high temperature is measured. The degree of voltage drop is used to check whether excessive self-discharge has occurred. This process is a continuous measurement process with the aging process (S11). Since time has passed after the aging process (S11), the self-discharge inspection process (S12) is performed at room temperature, for example, around 20°C.

[0119] <Outgoing Inspection Procedure (S13)>

[0120] In the shipment inspection process (S12), inspections are performed on appearance or leakage, battery cell voltage, battery internal resistance, etc., and products exhibiting specific performance are designated as finished products. The shipment inspection process (S12) is performed, for example, at a room temperature of 20°C. The inspected automotive lithium-ion secondary batteries 1 are stacked in multiples to form a battery stack. At this time, the battery stack is constrained under a compression state of 200 to 10000 N, preferably 3000 to 6000 N. A range of arbitrary combinations of the above upper and lower limits is also assumed.

[0121] Multiple battery stacks are further housed in a container, and control devices, various sensors, etc. are installed to form a battery pack for vehicles.

[0122] (Example)

[0123] Figure 6 This is a flowchart illustrating process A for adjusting the spring constant of this embodiment, and processes B and C as comparative examples. Process A is a combination of conditions for the processes related to adjusting the spring constant in the manufacturing processes S1 to S13 of the lithium-ion secondary battery 1 described above.

[0124] Figure 7 It is a table showing the conditions for process A, process B, and process C.

[0125] <Conditions for the winding and pressing process>

[0126] First, in the winding pressing process (S4), the electrode body 10 is compressed from the thickness direction D by a press 2 having a pressing surface 2a composed of a pair of opposing planes, clamping the flat portion F with a force of less than 100 kN. This "compression" differs from the "constraint" of this embodiment. Regarding this pressing, at a room temperature of 25°C and with a pressing force not exceeding 100 kN, the electrode body 10 is compressed using a force greater than that used in "constraint".

[0127] As a result, the porous structure of the spacer 120 is flattened, a portion of the spacer 120 undergoes plastic deformation, and the spring constant H (the spring constant of the spacer 120 under high load) increases. However, since the winding pressing process (S4) is carried out at room temperature of around 25°C, the plastic deformation is limited. This condition is the same as in processes A, B, and C.

[0128] <Conditions for the battery cell drying process>

[0129] Next, in the battery cell drying process (S8), the temperature is set to a high temperature of 105°C. At this time, the cell is not constrained. If the cell is constrained at such a high temperature, the material of the separator 120 softens and becomes susceptible to plastic deformation, thus the separator 120 is flattened and the spring constant increases rapidly. This condition is the same as in processes A, B, and C.

[0130] <Conditions for the initial charging process>

[0131] In the initial charging step (S10), charging is performed slowly at a low charging rate, resulting in minimal heat generation. In this embodiment, the initial charging step (S10) is performed at approximately 25°C. Here, since it is within the normal temperature range, constraint is applied under a load of 10 kN or less. Because constraint is performed at normal temperature and under low load, it has the effect of only increasing the spring constant L.

[0132] This condition is the same for processes A, B, and C.

[0133] <Conditions for the aging process>

[0134] In the aging process (S11), the battery is heated to melt the fine metal particles. In process A, the battery temperature is maintained at a high temperature of 60°C. Here, in process A, the separator 120 is at a high temperature and is in a state prone to plastic deformation. Therefore, to avoid a sharp increase in the spring constant, no constraint is applied. Similarly, no constraint is applied in process B. In contrast, constraint is applied in process C. Therefore, in process C, the spring constant increases, especially the spring constant H, which increases significantly.

[0135] <Conditions for Self-Discharge Inspection Procedure>

[0136] In the self-discharge inspection process (S12), after the aging process (S11), the cell is constrained for a certain period of time at a temperature of 20°C (room temperature) with a load of less than 10 kN. The constraint continues until the inspection is completed. Therefore, in process A, only the spring constant L increases, and the difference between L and the spring constant H decreases, thus reducing the L / H ratio.

[0137] This condition applies only to process A. For processes B and C, since no constraints are applied, the conditions for process A differ from those for processes B and C. Specifically, in process B, because the constraint is only applied to the initial charging step (S10), the separator 120 is flexible, and both the spring constant H and the spring constant L decrease.

[0138] <Conditions for Outgoing Inspection Process>

[0139] In the outgoing inspection process (S13), visual inspection or leakage checks, battery cell voltage checks, and internal battery resistance checks are performed. Notably, no heating or heat generation is required. In process A, the battery stack is constrained at a normal temperature of 20°C with a load of less than 10 kN until the inspection is completed. Therefore, only the spring constant L increases.

[0140] This condition applies only to process A. For processes B and C, since no direct or indirect constraints are applied to the electrode body, the conditions differ between process A and processes B and C. Specifically, in process B, because the constraints are only applied during the initial charging process (S10), the spacer 120 is flexible, and both the spring constant H and the spring constant L are reduced.

[0141] (Example)

[0142] High-rate aging test

[0143] In this embodiment, the present disclosure is verified through Examples 1-8 and Comparative Examples 1 and 2. In Examples 1-8, lithium-ion secondary batteries 1 were manufactured using process A with modified conditions. In Comparative Example 1, lithium-ion secondary batteries 1 were manufactured using process B. In Comparative Example 2, lithium-ion secondary batteries 1 were manufactured using process C. Subsequently, for each lithium-ion secondary battery 1, the degree of high-rate aging was tested using a rectangular wave test.

[0144] <Rectangular Wave Experiment>

[0145] Figure 8 This is a diagram showing a rectangular wave test used to test the high-rate aging of the lithium-ion secondary battery 1 of this embodiment.

[0146] The rectangular wave test involves applying a current of tens to hundreds of amperes for several seconds to tens of seconds, and then repeatedly applying approximately one-tenth of that current in the opposite direction with the same capacity. Through this repetition, high-rate aging is generated during high-rate charge and discharge.

[0147] In this embodiment, the lithium-ion secondary battery 1 is charged at 100A for 10 seconds and discharged at 10A for 100 seconds at a battery temperature of 25°C. Specifically, the current is set to 0A from the start until 5 seconds later. After 5 seconds, the current is increased from 0A to 100A to charge the lithium-ion secondary battery 1. Then, after 15 seconds, the current is changed from 100A to 0A, ending the charging process. Further, after 20 seconds, the current is changed from 0A to -10A to discharge the lithium-ion secondary battery 1 for 100 seconds. Then, after 120 seconds, the current is changed from -10A to 0A, and one cycle ends after 125 seconds. This cycle is repeated 1000 times.

[0148] Furthermore, the internal resistance [Ω] of the battery cell was measured before the inspection and after 1000 cycles, and the increase rate was calculated.

[0149] <Constraints>

[0150] Regarding the constraint, the load on the electrode 10 is measured directly or indirectly using the Autograph precision universal testing machine (a registered trademark of Shimadzu Corporation). In this embodiment, the constraint is set to 4500 [N].

[0151] Results of High-Rate Aging Tests

[0152] Figure 9 This is a table showing the test results of the embodiments and comparative examples of this implementation. Figure 10 This is a diagram illustrating the test results of embodiments and comparative examples of this implementation.

[0153] <Process A>

[0154] Examples 1-8 are the results of measuring the resistance rise rate of lithium-ion secondary batteries 1 manufactured in process A by changing conditions such as the number of windings and the composition of composite material layers.

[0155] As a result, the spring constant H ranged from 164 to 239, while the corresponding spring constant L ranged from 58 to 90. The ratio of spring constant L to spring constant H was in the range of L / H = 0.34 to 0.41. That is, the constraint conditions (e.g., constraint temperature, load, time) were set in a manner where the ratio of spring constant L to spring constant H, L / H, was in the range of L / H = 0.34 to 0.41. The rate of increase in resistance (the rate of increase in internal resistance [Ω] before and after the rectangular wave test) was in the range of 1.09 to 1.17.

[0156] <Process B>

[0157] In contrast, Comparative Example 1 shows the results of measuring the resistance rise rate of the lithium-ion secondary battery 1 manufactured in Process B. In Process B, the constraint is only performed in the initial charging process (S10), so the separator 120 is flexible, and both the spring constant H and the spring constant L are reduced.

[0158] As a result, the spring constant H is 183, and the corresponding spring constant L is 58. The ratio of spring constant L to spring constant H is L / H = 0.32. The rate of increase in resistance is 1.24.

[0159] <Process C>

[0160] Comparative Example 2 shows the results of measuring the resistance rise rate of the lithium-ion secondary battery 1 manufactured in Process C. In Process C, the battery is constrained during an aging process (S11) at high temperature. As a result, in Process C, the porous structure of the separator 120, which softens at high temperature, is flattened and undergoes plastic deformation, leading to an increase in the spring constant, and particularly a significant increase in the spring constant H.

[0161] As a result, the spring constant H is extremely high, at 238. In contrast, the spring constant L increases to 102. The ratio of spring constant L to spring constant H is L / H = 0.42. The rate of increase in resistance is high, at 1.21.

[0162] <Conclusion of the experiment>

[0163] The conclusion drawn from the above experiments is that the resistance rise rate of the lithium-ion secondary battery 1 manufactured in process A is suppressed to 1.09–1.17. On the other hand, the resistance rise rates of Comparative Example 1 manufactured in process B and Comparative Example 2 manufactured in process C show high values ​​of 1.21–1.24. This proves that, compared with the lithium-ion secondary batteries 1 manufactured in processes B and C, the lithium-ion secondary battery 1 manufactured in process A is less prone to significant high-rate aging.

[0164] In other words, by keeping the ratio of spring constant L to spring constant H in the range of L / H = 0.34 to 0.41, the rate of increase in resistance was suppressed to 1.09 to 1.17. Therefore, it can be seen that the rate of increase in resistance can be suppressed by controlling the ratio of spring constant L to spring constant H.

[0165] (The function of this implementation method)

[0166] Regarding high-rate aging, during repeated high-rate charge-discharge cycles, the active material layer in the flat, wound electrode body 10 expands / contracts with each charge and discharge. This causes the pressure within the electrode body 10 to rise or fall. Consequently, the concentration of the supporting salt may become uneven, or the non-aqueous electrolyte 17 may leak out of the electrode body 10, resulting in electrolyte drying. As a result, the internal resistance of the lithium-ion secondary battery 1 may increase. This leads to performance degradation.

[0167] In this embodiment, the hardness of the electrode body 10 is determined by using spring constants H and L to control the hardness of the electrode body 10 during expansion and contraction.

[0168] However, it has been found that even under such usage conditions, when the ratio of spring constant L to spring constant H, L / H, is 0.34≤L / H≤0.41, the balance is good and there is little high-rate aging.

[0169] Furthermore, it was discovered that, in order to achieve this, by directly or indirectly constraining the electrode body 10 only under room temperature processing, the spring constant on the low load side can be specifically increased. By utilizing this characteristic, a manufacturing method is constructed in which the ratio of spring constant L to spring constant H, L / H, is 0.34 ≤ L / H ≤ 0.41.

[0170] Therefore, in the lithium-ion secondary battery 1 of this embodiment, the pressure rise or fall inside the electrode body 10 can be suppressed, the uneven distribution of the concentration of the supporting salt can be suppressed, or the non-aqueous electrolyte 17 may flow out to the outside of the electrode body 10 and cause the electrolyte to dry out.

[0171] Specifically, under high load and high SOC conditions, the electrode body 10 expands. In this state, by making the electrode body 10 flexible, it can absorb volume changes, preventing the non-aqueous electrolyte 17 from being discharged during expansion. Thus, the liquid retention capacity of the non-aqueous electrolyte 17 under high SOC conditions can be maintained at a high level.

[0172] On the other hand, under low load and low SOC conditions, the electrode body 10 shrinks. In this state, by hardening the electrode body 10, volume change can be suppressed, preventing the non-aqueous electrolyte 17 from being discharged during shrinkage. Thus, even under low SOC conditions, the liquid retention capacity of the non-aqueous electrolyte 17 can be maintained at a high level.

[0173] By taking both aspects into account, it is possible to produce lithium-ion secondary batteries with high rate of change and low aging.

[0174] (Effects of this implementation method)

[0175] (1) According to the lithium-ion secondary battery 1 and its manufacturing method in this embodiment, the electrode body 10 does not become complicated, and even if it is used in a manner of repeated high-rate charging and discharging, degradation can be reduced.

[0176] (2) The salt concentration unevenness can be reduced by electrode body 10 alone. Usually, in order to control the spring constant in the process, no special equipment is required, and high-rate aging can be effectively suppressed without increasing the cost.

[0177] (3) In addition, the lithium-ion secondary battery 1 of this embodiment does not require a special structure and does not have the risk of reduced voltage life due to damage to the battery casing 11 or lithium deposition due to local electrochemical reaction.

[0178] (4) The manufacturing method of the lithium-ion secondary battery 1 in this embodiment can be implemented only by "constraining" specific conditions, so it can be applied to the manufacturing of existing lithium-ion secondary batteries 1 using existing production equipment.

[0179] (Other examples)

[0180] • In this embodiment, the present disclosure is described using a lithium-ion secondary battery 1 as an example, but it can also be applied to other non-aqueous electrolyte secondary batteries.

[0181] • In this embodiment, a thin-plate lithium-ion secondary battery 1 for automotive use is shown, but it can also be applied to cylindrical batteries, etc. Furthermore, it is not limited to automotive use, but can also be applied to marine, aircraft, and stationary batteries.

[0182] • The constraints of process A, such as temperature, load, and time, are used as examples of constraints. For the characteristics of the target battery, those skilled in the art can optimize the temperature, load, and time constraints to reduce high-rate aging.

[0183] · Figure 5 , Figure 6 The flowchart shown is illustrative. Those skilled in the art can add, remove, or modify the process, and may change the order of implementation.

[0184] • Regarding high-rate aging, an inspection was conducted using a rectangular wave test, but the evaluation of high-rate aging is not limited to inspections conducted using a rectangular wave test, as long as it is possible to perform such an evaluation.

[0185] This disclosure can, of course, be implemented by those skilled in the art by adding, deleting, altering, or changing the order of its components without departing from the scope of the claims.

Claims

1. A non-aqueous electrolyte secondary battery, comprising an electrode body, a non-aqueous electrolyte, and a flat, rectangular battery casing housing the electrode body and the non-aqueous electrolyte, characterized in that... In the electrode body, a positive electrode comprising a positive electrode substrate and a positive electrode composite material layer, and a negative electrode comprising a negative electrode substrate and a negative electrode composite material layer, are laminated and wound together with a separator formed of porous resin to form a flat shape. Assuming a thickness of 316 N / cm is applied to the non-aqueous electrolyte secondary battery,... 2 ~210N / cm 2 The spring constant of the non-aqueous electrolyte secondary battery under load is H. Assume a load of 95 N / cm is applied to the non-aqueous electrolyte secondary battery in the thickness direction. 2 ~74N / cm 2 When the spring constant of the non-aqueous electrolyte secondary battery under load is the spring constant L, The ratio of the spring constant L to the spring constant H, L / H, is 0.34 ≤ L / H ≤ 0.

41. The non-aqueous electrolyte secondary battery is a lithium-ion secondary battery.

2. A method for manufacturing a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery comprising an electrode body, a non-aqueous electrolyte, and a flat, cuboid battery casing housing the electrode body and the non-aqueous electrolyte, characterized in that... Only when the non-aqueous electrolyte secondary battery is at a room temperature of 10℃ to 35℃, is the electrode body directly or indirectly constrained by pressure applied in the thickness direction. Assuming a thickness of 316 N / cm is applied to the non-aqueous electrolyte secondary battery,... 2 ~210N / cm 2 The spring constant of the non-aqueous electrolyte secondary battery under load is H. Assume a load of 95 N / cm is applied to the non-aqueous electrolyte secondary battery in the thickness direction. 2 ~74N / cm 2 When the spring constant of the non-aqueous electrolyte secondary battery under load is the spring constant L, The constraint conditions are set according to the ratio of the spring constant L to the spring constant H, L / H being 0.34 ≤ L / H ≤ 0.

41. The non-aqueous electrolyte secondary battery is a lithium-ion secondary battery.

3. The method for manufacturing a non-aqueous electrolyte secondary battery as described in claim 2, characterized in that, The method includes the following steps: In the winding process, the positive electrode of the electrode body, which includes a positive electrode substrate and a positive electrode composite material layer, and the negative electrode, which includes a negative electrode substrate and a negative electrode composite material layer, are laminated and wound together with a separator made of porous resin. The winding pressing process flattens the wound electrode body into a flat shape. The battery cell drying process involves drying the electrode body inside the battery casing. Initial charging process; Aging process; as well as Inspection process, The constraint is performed in at least one of the initial charging process and the inspection process. The constraint is not applied during the battery cell drying process and the aging process.

4. The method for manufacturing a non-aqueous electrolyte secondary battery as described in claim 2 or 3, characterized in that, The pressure applied during the constraint is 210 N / cm. 2 Perform under the following load range.

5. The method for manufacturing a non-aqueous electrolyte secondary battery as described in claim 2 or 3, characterized in that, The non-aqueous electrolyte secondary battery is a lithium-ion secondary battery.

Images