Manufacturing method for non-aqueous secondary batteries

Abstract

The present invention provides a method for manufacturing a non-aqueous secondary battery that reduces the reaction resistance in the central part of the electrode body in the winding axis direction. [Solution] The non-aqueous secondary battery comprises an electrode body in which a positive electrode sheet and a negative electrode sheet are stacked and wound with a separator in between, and a non-aqueous electrolyte containing a film-forming agent containing a lithium salt. The negative electrode sheet has a negative electrode composite layer containing a negative electrode active material and a binder containing a sodium salt. The method for manufacturing the non-aqueous secondary battery includes a heating step in which the wound body 20 is placed in a battery case 11, the non-aqueous electrolyte is injected into the battery case 11, and then the central part of the wound body 20 in the winding axis direction is heated with a heating element 40.

Description

Technical Field

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

Background Art

[0002] In the method for manufacturing a non-aqueous secondary battery described in Patent Document 1, a film-forming agent containing lithium is added to the non-aqueous electrolyte. The film-forming agent is lithium bis(oxalato)borate (LiBOB), which is an example of a lithium salt. The electrode body used in the non-aqueous secondary battery contains a sodium salt. When the electrode body contains a large amount of Na, BOB ions ionized from LiBOB combine with Na ions ionized from the sodium salt to form a NaBOB film.

Prior Art Documents

Patent Documents

[0003] 1]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the method for manufacturing a non-aqueous secondary battery described in Patent Document 1 above, the electrolyte penetrates from the end of the electrode body to the electrode plate. Also, the diffusion rate of Na ions dissolved in the electrolyte is faster than that of BOB ions. For this reason, when NaBOB is generated at the central part of the electrode plate, BOB ions do not spread to the central part of the electrode plate. And a portion where the LiBOB film is thin occurs at the central part of the electrode plate. When charge and discharge are repeated in a non-aqueous secondary battery using such an electrode plate, the decomposition of the electrolyte becomes remarkable at a portion where the film-forming agent is relatively less. And a high-resistance film is formed at a portion where the film-forming agent is less, and lithium precipitation occurs. [[ID=

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Means for Solving the Problems

[0005] A method for manufacturing a non-aqueous secondary battery that solves the above problems comprises an electrode body in which a positive electrode sheet and a negative electrode sheet are laminated and wound together with a separator in between, and a non-aqueous electrolyte containing a film-forming agent containing a lithium salt, wherein the negative electrode sheet has a negative electrode composite layer containing a negative electrode active material and a binder containing a sodium salt, and the method includes a heating step of housing the electrode body in a battery case, injecting the non-aqueous electrolyte into the battery case, and then heating the central part of the electrode body in the winding axis direction.

[0006] During aging, sodium ions dissolved in the non-aqueous electrolyte and ions from the film-forming agent containing lithium salt actively react in the central part of the electrode body, forming a high-resistance film. According to the above method, after injecting the non-aqueous electrolyte into the battery case, the central part of the electrode body in the winding axis direction is heated. As a result, the binder present in the central part of the electrode body in the winding axis direction, which has high resistance, dissolves, increasing the reaction area of ​​the negative electrode active material, and thereby reducing the reaction resistance in the central part of the electrode body in the winding axis direction.

[0007] The method for manufacturing a non-aqueous secondary battery described above preferably includes a dissolution amount calculation step, which calculates the amount of dissolution corresponding to a specified reaction resistance based on a known correspondence between the amount of binder dissolved by heating in the heating step and the reaction resistance of the electrode body, and a heating condition determination step, which determines the heating conditions based on a known correspondence between the amount of dissolution and the heating conditions for heating.

[0008] In the above method for manufacturing a non-aqueous secondary battery, it is preferable to heat the battery case by applying a heating element to the outer surface of the battery case in the heating step. [Effects of the Invention]

[0009] According to the present invention, the reaction resistance in the central part of the electrode body in the winding axis direction can be reduced. [Brief explanation of the drawing]

[0010] [Figure 1]This is a perspective view showing the schematic configuration of a non-aqueous secondary battery according to the first embodiment. [Figure 2] This is a diagram showing a portion of the electrode body of the same embodiment unfolded. [Figure 3] This figure shows the state of the negative electrode active material before and after aging in the same embodiment. [Figure 4] This is a graph showing the weight change of the test specimen in the same embodiment. [Figure 5] This graph shows the relationship between the aging temperature and the dissolution rate of the binder in the non-aqueous secondary battery of the same embodiment. [Figure 6] This graph shows the relationship between the elution rate of the binder and the relative ratio of the reaction resistance in the non-aqueous secondary battery of the same embodiment. [Figure 7] This figure shows the heating process of the non-aqueous secondary battery according to the same embodiment. [Figure 8] This graph shows the relationship between the measurement position and resistance of the non-aqueous secondary battery in the same embodiment. [Figure 9] This flowchart shows the method for manufacturing a non-aqueous secondary battery according to the same embodiment. [Modes for carrying out the invention]

[0011] [This Circumstance] An embodiment of a method for manufacturing a non-aqueous secondary battery will be described below with reference to Figures 1 to 9. A lithium-ion secondary battery will be described as an example of a non-aqueous secondary battery.

[0012] [Lithium-ion rechargeable battery 10] As shown in Figure 1, the lithium-ion secondary battery 10, which is a non-aqueous secondary battery, is a cell battery that forms a battery pack when multiple lithium-ion secondary batteries 10 are combined and enclosed in a resin or metal case. The battery pack is used in hybrid vehicles and electric vehicles.

[0013] The lithium-ion secondary battery 10 includes a battery case 11 and a lid body 12. The battery case 11 has a rectangular parallelepiped shape with an opening on the upper side. The lid body 12 seals the opening of the battery case 11. The battery case 11 and the lid body 12 are made of a metal such as aluminum or an aluminum alloy. The lithium-ion secondary battery 10 forms a sealed battery cell by attaching the lid body 12 to the battery case 11.

[0014] Two positive electrode external terminals 13A and a negative electrode external terminal 13B are provided on the lid body 12. The positive electrode external terminal 13A and the negative electrode external terminal 13B are used for charging and discharging electric power. A plurality of wound bodies 20 are housed inside the battery case 11. The wound body 20 is an electrode body. In the present embodiment, three wound bodies 20 are housed in the battery case 11. The positive electrode current collecting portion 20A, which is the end portion on the positive electrode side of the wound body 20, is electrically connected to the positive electrode external terminal 13A via the positive electrode current collecting member 14A. The negative electrode current collecting portion 20B, which is the end portion on the negative electrode side of the wound body 20, is electrically connected to the negative electrode external terminal 13B via the negative electrode current collecting member 14B. Also, a non-aqueous electrolyte is injected into the battery case 11 through a liquid injection hole (not shown). Note that the shapes of the positive electrode external terminal 13A and the negative electrode external terminal 13B are not limited to the shapes shown in FIG. 1 and may be any shape.

[0015] [Wound body 20] As shown in FIG. 2, the wound body 20 is a flat electrode body obtained by winding a laminate in which a long positive electrode sheet 21 and a negative electrode sheet 24 are laminated via a separator 27. The positive electrode sheet 21, the negative electrode sheet 24, and the separator 27 are laminated such that the direction along their respective lengths coincides with the longitudinal direction D1. Before winding, the laminate is laminated in the order of the positive electrode sheet 21, the separator 27, the negative electrode sheet 24, and the separator 27. The positive electrode sheet 21 and the negative electrode sheet 24 are electrode sheets.

[0016] [Positive electrode sheet 21] The positive electrode sheet 21 includes a positive electrode current collector 22 and a positive electrode composite material layer 23. The positive electrode current collector 22 is a foil-shaped positive electrode base material formed in a long strip shape. The positive electrode composite material layer 23 is provided on each of two opposing surfaces of the positive electrode current collector 22. The positive electrode current collector 22 includes a positive electrode side non-coated portion 22A at one end in the width direction D2 where the positive electrode current collector 22 is exposed without the formation of the positive electrode composite material layer 23.

[0017] The positive electrode current collector 22 is made of a metal foil composed of aluminum or an alloy mainly composed of aluminum. The positive electrode current collector 22 functions as a current collector in the positive electrode. The positive electrode side non-coated portion 22A provided in the positive electrode current collector 22 forms a positive electrode side current collecting portion 20A with the opposing surfaces being pressed against each other in the state of the wound body 20.

[0018] The positive electrode composite material layer 23 is a cured body of a liquid positive electrode composite material paste. The positive electrode composite material paste contains a positive electrode active material, a positive electrode solvent, a positive electrode conductive material, and a positive electrode binder. The positive electrode composite material layer 23 is formed by drying the positive electrode composite material paste and vaporizing the positive electrode solvent. Therefore, the positive electrode composite material layer 23 contains a positive electrode active material, a positive electrode conductive material, and a positive electrode binder.

[0019] The positive electrode active material is a lithium-containing composite oxide capable of occluding and releasing lithium ions, which are charge carriers in the lithium-ion secondary battery 10. The lithium-containing composite oxide is an oxide containing lithium and other metal elements other than lithium. The other metal elements other than lithium are, for example, at least one selected from the group consisting of nickel, cobalt, manganese, vanadium, magnesium, molybdenum, niobium, titanium, tungsten, aluminum, and iron contained as iron phosphate in the lithium-containing composite oxide.

[0020] For example, lithium-containing composite oxides include lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), and lithium manganate (LiMn2O4). Another example is lithium-containing composite oxide, a ternary lithium-containing composite oxide containing nickel, cobalt, and manganese, which is lithium nickel-cobalt-manganate (LiNiCoMnO2). Yet another example is lithium iron phosphate (LiFePO4).

[0021] The positive electrode solvent is an NMP (N-methyl-2-pyrrolidone) solution, which is an example of an organic solvent. Examples of positive electrode conductive materials include carbon black such as acetylene black and Ketjenblack, carbon fibers such as carbon nanotubes and carbon nanofibers, and graphite. The positive electrode binder is an example of a resin component contained in the positive electrode paste. Examples of positive electrode binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and styrene-butadiene rubber (SBR).

[0022] The positive electrode sheet 21 may have an insulating layer at the boundary between the uncoated portion 22A on the positive electrode side and the positive electrode composite layer 23. The insulating layer contains an inorganic component having insulating properties and a resin component that functions as a binder. The inorganic component is at least one selected from the group consisting of powdered boehmite, titania, and alumina. The resin component is at least one selected from the group consisting of PVDF, PVA, and acrylic.

[0023] [Negative electrode sheet 24] The negative electrode sheet 24 comprises a negative electrode current collector 25 and a negative electrode composite layer 26. The negative electrode current collector 25 is a foil-shaped negative electrode substrate formed in an elongated shape. The negative electrode composite layer 26 is provided on each of two opposing surfaces of the negative electrode current collector 25. The negative electrode current collector 25 has a negative electrode side unpainted portion 25A at one end in the width direction D2, which is located opposite the positive electrode side unpainted portion 22A, where the negative electrode composite layer 26 is not formed and the negative electrode current collector 25 is exposed.

[0024] The negative electrode current collector 25 is made of metal foil composed of copper or an alloy mainly composed of copper. The negative electrode current collector 25 functions as a current collector at the negative electrode. In the state of the wound body 20, the unpainted negative electrode side portion 25A has opposing surfaces pressed against each other to form the negative electrode side current collector portion 20B.

[0025] The negative electrode composite layer 26 is a cured body of a liquid negative electrode composite paste. The negative electrode composite paste contains a negative electrode active material, a lithium salt, a negative electrode solvent, a negative electrode thickener, and a negative electrode binder. The negative electrode composite layer 26 is formed when the negative electrode composite paste dries and the negative electrode solvent vaporizes. Therefore, the negative electrode composite layer 26 contains the negative electrode active material, a lithium salt, and further, as additives, a negative electrode thickener and a negative electrode binder. The negative electrode composite layer 26 may further contain additives such as a conductive material.

[0026] The negative electrode active material is a material capable of intercalating and releasing lithium ions. Examples of negative electrode active materials include carbon materials such as graphite, poorly graphitizable carbon, and easily graphitizable carbon. In this embodiment, graphite is used as the negative electrode active material. The negative electrode solvent is, for example, water. The lithium salt can be one or more lithium compounds (lithium salts) selected from LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC4F9SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiI, LiBOB (lithium bisoxalate borate), etc. In this embodiment, LiPF6 is used as the lithium salt. As an example of a negative electrode thickener, CMC (carboxymethylcellulose) can be used as a thickener containing a sodium salt. The negative electrode binder can be the same as that used for the positive electrode binder. As an example of a negative electrode binder, SAR (styrene-acrylic acid copolymer) can be used as a binder containing a sodium salt.

[0027] [Separator 27] The separator 27 prevents contact between the positive electrode sheet 21 and the negative electrode sheet 24, and holds the non-aqueous electrolyte between the positive electrode sheet 21 and the negative electrode sheet 24. When the wound body 20 is immersed in the non-aqueous electrolyte, the non-aqueous electrolyte penetrates from the ends in the width direction D2 of the separator 27 toward the center.

[0028] The separator 27 can be, for example, a porous polymer membrane such as a porous polyethylene membrane, a porous polyolefin membrane, or a porous polyvinyl chloride membrane, or an ion-conductive polymer electrolyte membrane. In this embodiment, a porous polyolefin membrane is used as the separator 27.

[0029] [Nonaqueous electrolyte] The non-aqueous electrolyte is a composition containing a supporting salt in a non-aqueous solvent. As the non-aqueous solvent, one or more materials selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, etc., can be used. As the supporting salt, one or more lithium compounds (lithium salts) selected from LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC4F9SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiI, etc., can be used. In this embodiment, LiBOB is added as an additive to the non-aqueous electrolyte.

[0030] Here, if the wound body 20 contains a large amount of Na, BOB ions ionized from LiBOB combine with Na ions ionized from the sodium salt to form a NaBOB film. The non-aqueous electrolyte penetrates the electrode plate of the wound body 20 from the edges. Also, the diffusion rate of Na ions dissolved in the non-aqueous electrolyte is faster than that of BOB ions. Therefore, because NaBOB is generated in the central part of the wound body 20 in the direction of the winding axis, BOB ions do not reach the central part of the wound body 20 in the direction of the winding axis. As a result, areas with less LiBOB film are generated in the central part of the electrode plate. When charging and discharging are repeated in a lithium-ion secondary battery 10 using such an electrode plate, the decomposition of the electrolyte becomes significant in the central part where the film-forming agent is relatively small, and a high-resistance film is formed, causing lithium deposition. As a result, as shown in Figure 8, the reaction resistance of the central part of the wound body 20 in the direction of the winding axis becomes higher than the reaction resistance of the edges.

[0031] [Negative electrode active material 30] As shown in Figure 3, the negative electrode active material 30 is coated with a negative electrode binder 31 and a SEI (Solid Electrolyte Interphase) film 32. When heating is performed, and the heating temperature is increased or the heating time is increased, the amount of negative electrode binder 31 bound to the negative electrode active material 30 that dissolves increases, increasing the reaction area of ​​the negative electrode active material 30 and thus reducing the reaction resistance. In this embodiment, this reduction in reaction resistance due to heating is utilized. That is, the variation in reaction resistance in the winding axis direction of the winding body 20 is adjusted by heating the high-resistance areas so that the reaction resistance of the winding body 20 falls within a predetermined reaction resistance.

[0032] As shown in Figure 4, a test specimen was prepared by drying 1 g of negative electrode binder. Let the weight of this test specimen be W1. Next, the prepared test specimens were immersed in 20 cc of non-aqueous electrolyte solution and left to stand at 60°C and 70°C for 3 days before being removed from the non-aqueous electrolyte solution. The weight of the test specimens after immersion is denoted as W2. This 3-day standing period corresponds to heating.

[0033] Next, the test specimen was air-dried for 7 days. The weight of the test specimen after drying is denoted as W3. Note that weight W3 includes the weight of the lithium salt in the electrolyte absorbed by the negative electrode binder, so it is necessary to subtract the weight of the lithium salt. Therefore, the weight increase of the test specimen W2-W1 is taken as the amount of electrolyte absorbed by the negative electrode binder, and the weight obtained by subtracting the weight of the lithium salt from that increase using theoretical calculation is denoted as W4.

[0034] The elution rate of the negative electrode binder was then calculated using the following formula. Elution rate [%]=(W1-W4) / W1*100 As shown in Figure 5, it can be seen that the higher the heating temperature, the higher the dissolution rate. Similarly, instead of changing the temperature, increasing the heating time at the same temperature can also increase the dissolution rate.

[0035] [Method for determining heating conditions] First, based on the known correspondence between the amount of negative electrode binder 31 eluted by heating and the reaction resistance of the electrode body, the amount of elution corresponding to a specified reaction resistance is calculated. That is, the amount of elution is calculated from the correspondence so that the reaction resistance of the central part in the winding axis direction of the wound body 20 becomes the specified reaction resistance. This process corresponds to the elution amount calculation step.

[0036] Next, the heating conditions are determined based on the known correspondence between the amount of elution and the heating conditions. That is, the temperature or time, which is the heating condition, is calculated from the amount of elution of the negative electrode binder 31. This process corresponds to the heating condition determination step.

[0037] As shown in Figure 7, the heating element 40 is applied to the center of the outer surface of the battery case 11 in the direction of the winding axis, thereby heating the center of the winding body 20 in the direction of the winding axis. The width of the heating element 40 in the direction of the winding axis corresponds to the width X of the resistance peaks P1 and P2 of the winding body 20 shown in Figure 8. The width of the heating element 40 may be such that it includes the range where the resistance of the winding body 20 is higher than the ends in the direction of the winding axis. This process corresponds to the heating step.

[0038] As shown in Figure 6, an electrode body was fabricated using a negative electrode sheet 24 containing graphite as the negative electrode active material, CMC as the negative electrode thickener, and SAR as the negative electrode binder, and the effect of reducing the reaction resistance in the central part of the electrode body in the winding axis direction was confirmed. The reaction resistance in Figure 6 shows the relative ratio with that of the case without heating. As the dissolution rate increases, the reaction resistance decreases.

[0039] [Manufacturing method] Next, with reference to Figure 9, a method for manufacturing the lithium-ion secondary battery 10 will be described. The method for manufacturing the lithium-ion secondary battery 10 includes a source process, a lamination process, a winding process, a winding body pressing process, an assembly process, a liquid injection and sealing process, an activation process, and an inspection process.

[0040] [Source process] In the source process of step S1 in Figure 9, a positive electrode composite paste is prepared by kneading the positive electrode active material, positive electrode conductive material, and positive electrode binder that constitute the positive electrode composite layer 23. Similarly, a negative electrode composite paste is prepared by kneading the negative electrode active material 30, lithium salt, negative electrode solvent, negative electrode thickener, and negative electrode binder 31 that constitute the negative electrode composite layer 26. Next, the positive electrode composite paste is applied to the positive electrode current collector 22 to prepare the positive electrode sheet 21. Similarly, the negative electrode composite paste is applied to the negative electrode current collector 25 to prepare the negative electrode sheet 24. Subsequently, the positive electrode sheet 21 and the negative electrode sheet 24 are compressed to a specified thickness and then cut to a specified width.

[0041] [Lamination process] Next, in the lamination process of step S2 in Figure 9, a laminate is created by laminating a positive electrode sheet 21 and a negative electrode sheet 24 with a separator 27 in between. The laminate is formed by laminating the positive electrode sheet 21, separator 27, negative electrode sheet 24, and separator 27 in that order.

[0042] [Winding process] Next, in the winding process of step S3 in Figure 9, a wound body 20 is produced by winding a laminate formed by stacking the positive electrode sheet 21, the negative electrode sheet 24, and the separator 27. In the winding process, the wound body 20 is produced by winding it onto a winding core (not shown). The wound body 20 is formed into a flattened shape by compressing it from both sides.

[0043] [Rolled body pressing process] Next, in the winding press process of step S4 in Figure 9, a flattened winding body 20 is formed by compressing the substantially cylindrical winding body 20 from both sides.

[0044] [Assembly Process] Next, in the assembly process of step S5 in Figure 9, the positive electrode external terminal 13A is joined to the positive electrode side current collector portion 20A, which is the positive electrode end of the winding body 20 in the axial direction, via the positive electrode side current collector member 14A. The negative electrode external terminal 13B is joined to the negative electrode side current collector portion 20B, which is the negative electrode end of the winding body 20 in the axial direction, via the negative electrode side current collector member 14B. Finally, the winding body 20 is housed in the battery case 11.

[0045] [Liquid injection / sealing process] Next, in the liquid injection and sealing process of step S6 in Figure 9, a non-aqueous electrolyte is injected through an inlet (not shown) formed in the lid 12, and a cap (not shown) is attached to the inlet, for example by laser welding, to seal it.

[0046] [High resistance part heating process] Next, in step S7 of Figure 9, the high-resistance portion heating step, the heating element 40 is applied to the outer surface of the battery case 11 to heat the central part of the winding body 20 in the winding axis direction. The central part of the winding body 20 in the winding axis direction corresponds to the high-resistance portion. The heating conditions are predetermined according to the lithium-ion secondary battery 10 manufactured from similar materials. Based on the known correspondence between the amount of negative electrode binder 31 dissolved by heating and the reaction resistance of the electrode body, the amount of dissolution corresponding to a specified reaction resistance is calculated. Then, based on the known correspondence between the amount of dissolution and the heating conditions, the temperature or time, which is the heating condition, is determined. The width of the heating element 40 in the winding axis direction is also predetermined. Step S7 corresponds to the heating step.

[0047] [Activation process] Next, in the activation step S8 of Figure 9, the lithium-ion secondary battery 10 is initially charged and stored at a high temperature for a certain period of time to perform aging, which dissolves metallic foreign matter and stabilizes the SEI (Solid Electrolyte Interphase) coating. Due to the aging, sodium ions dissolved in the non-aqueous electrolyte and ions of the film-forming agent containing lithium salt react actively in the central part of the wound body 20, forming a high-resistance coating. On the other hand, the negative electrode binder 31 present in the central part of the wound body 20 in the direction of the winding axis dissolves, increasing the reaction area of ​​the negative electrode active material 30, thereby reducing the reaction resistance in the central part of the wound body 20 in the direction of the winding axis.

[0048] [Inspection Process] Next, in the inspection process of step S9 in Figure 9, the cell voltage and battery resistance are inspected to select a lithium-ion secondary battery 10 that exhibits the specified performance.

[0049] Next, the effects of this embodiment will be described. (1) After injecting a non-aqueous electrolyte into the battery case 11, the central part of the winding body 20 in the winding axis direction is heated. As a result, the negative electrode binder 31 present in the central part of the winding body 20 in the winding axis direction, which has high resistance, dissolves, increasing the reaction area of ​​the negative electrode active material 30, thereby reducing the reaction resistance in the central part of the winding body 20 in the winding axis direction.

[0050] (2) Based on the known correspondence between the amount of negative electrode binder 31 eluted by heating and the reaction resistance of the wound body 20, the amount of eluted corresponding to the specified reaction resistance is calculated, and the heating conditions are determined based on the known correspondence between the amount of eluted and the heating conditions. Therefore, the heating conditions can be determined so that the specified reaction resistance is achieved.

[0051] (3) By applying the heating element 40 to the outer surface of the battery case 11, the central part of the winding body 20 in the winding axis direction is heated through the battery case 11. Therefore, the heating treatment can be easily performed without processing the battery case 11.

[0052] (Other embodiments) The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0053] In the above embodiment, the amount of negative electrode binder 31 eluted was changed by changing either the time or the temperature as heating conditions. However, the amount of negative electrode binder 31 eluted may also be changed by changing both the time and the temperature as heating conditions.

[0054] In the above embodiment, the heating element 40 was applied to the center of the outer surface of the battery case 11 in the direction of the winding axis, thereby heating the center of the winding body 20 in the direction of the winding axis via the battery case 11. However, the heating element may also be inserted inside the battery case 11 to heat the center of the winding body 20 in the direction of the winding axis.

[0055] In the above embodiment, the heating element 40 was applied to the center of the outer surface of the battery case 11 in the direction of the winding axis. However, the center of the winding body 20 in the direction of the winding axis may be heated by blowing warm air or hot air onto the center of the outer surface of the battery case 11 in the direction of the winding axis.

[0056] In the above embodiment, the amount of elution corresponding to a specified reaction resistance was calculated based on a known correspondence between the amount of negative electrode binder 31 eluted by heating and the reaction resistance of the wound body 20, and the heating conditions were determined based on a known correspondence between the amount of elution and the heating conditions. However, if the central part of the wound body 20 in the direction of the winding axis can be heated, it is not necessary to determine the detailed heating conditions.

[0057] The lithium-ion secondary battery 10 may be installed in automated transport machines, special vehicles for cargo handling, electric vehicles, hybrid vehicles, etc., as well as in computers and other electronic devices, or it may constitute a system other than those mentioned above. For example, it may be installed in mobile objects such as ships and aircraft, or it may be part of a power supply system that supplies electricity from a power plant to buildings and homes where the secondary battery is installed via a substation or the like. [Explanation of symbols]

[0058] 10…Lithium-ion rechargeable battery 11…Battery case 12... Lid 13A... Positive external terminal 13B…Negative external terminal 14A... Positive electrode current collector 14B... Negative electrode current collector 20...Wound body 20A... Positive electrode current collector 20B... Negative electrode current collector 21…Positive electrode sheet 22...Positive electrode current collector 22A...Unpainted area on the positive electrode side 23…Positive electrode composite layer 24... Negative electrode sheet 25...Negative electrode current collector 25A...Unpainted area on the negative electrode side 26…Negative electrode composite material layer 27... Separator 30...Negative electrode active material 31... Negative electrode binder 32...SEI coating

Claims

1. A method for manufacturing a non-aqueous secondary battery comprising an electrode body in which a positive electrode sheet and a negative electrode sheet are laminated and wound with a separator in between, and a non-aqueous electrolyte containing a film-forming agent containing a lithium salt, The negative electrode sheet has a negative electrode composite layer comprising a negative electrode active material and a binder containing a sodium salt. The heating step includes housing the electrode body in a battery case, injecting the non-aqueous electrolyte into the battery case, and then heating the central portion of the electrode body in the winding axis direction. A method for manufacturing a non-aqueous secondary battery.

2. A step to calculate the amount of dissolution corresponding to a specified reaction resistance, based on a known correspondence between the amount of binder dissolved by heating in the heating step and the reaction resistance of the electrode body, The step includes determining the heating conditions based on a known correspondence between the amount of elution and the heating conditions. A method for manufacturing a non-aqueous secondary battery according to claim 1.

3. In the heating step, the outer surface of the battery case is heated by applying a heating element to it. A method for manufacturing a non-aqueous secondary battery according to claim 1 or 2.

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