Method for evaluating inter-electrode distance of nonaqueous electrolyte secondary battery and method for manufacturing nonaqueous electrolyte secondary battery

Abstract

To provide a method for evaluating an inter-electrode distance of a nonaqueous electrolyte secondary battery, capable of simply evaluating the propriety of an inter-electrode distance of an electrode body in a short time, and a method for manufacturing the nonaqueous electrolyte secondary battery.SOLUTION: During a manufacturing process of a nonaqueous electrolyte secondary battery 10 in which an electrode body 1, a nonaqueous electrolyte 2 permeated into the electrode body, and a surplus electrolyte 2Y not permeated into the electrode body are housed in a case 3, a method for evaluating an inter-electrode distance of the nonaqueous electrolyte secondary battery includes: an electrolyte injection step S1 of injecting a nonaqueous electrolyte into the case; an electrolyte forcible permeation step S3 of forcibly permeating the surplus electrolyte in the case; a first liquid volume measurement step S2 of measuring a liquid amount L0 of the surplus electrolyte after the electrolyte injection step and before the electrolyte forcible permeation step; a second liquid volume measurement step S4 of measuring a liquid amount L1 of the surplus electrolyte after the electrolyte forcible permeation step; and an evaluation step S5 of, when a liquid change amount ΔL that is a difference of liquid amounts measured in the first liquid volume measurement step and the second liquid volume measurement step is equal to or less than a reference value KJ, evaluating that an inter-electrode distance DL of the electrode body is appropriate.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a method for evaluating an inter-electrode distance in an electrode assembly of a non-aqueous electrolyte secondary battery, and a method for manufacturing a non-aqueous electrolyte secondary battery using the method for evaluating the inter-electrode distance. [Background technology]

[0002] For example, Patent Document 1 discloses a lithium ion secondary battery including an electrode assembly having a positive electrode, a negative electrode, and a separator, a non-aqueous electrolyte, and a battery case that contains the electrode assembly and the non-aqueous electrolyte. It is known that such a lithium ion secondary battery may have a risk of metallic lithium (dendrite) being precipitated on the negative electrode side when it is charged for a long time with a large current, leading to a short circuit or deterioration of the electrode assembly.

[0003] There are various possible reasons for the precipitation of metallic lithium, but it has been found that one of the reasons is that the inter-electrode distance of the electrode body is partially wide. That is, when the inter-electrode distance is partially wide, a local overcharge state occurs at the change point of the inter-electrode distance, and lithium ions that have gathered in excess near the negative electrode receive electrons from the negative electrode and are likely to precipitate on the negative electrode as metallic lithium. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-67699 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the inter-electrode distance of the electrode body involved in the precipitation of metallic lithium can be measured by, for example, CT (Computed Tomography) image analysis, it is necessary to measure multiple cross sections, which lengthens the measurement and analysis time, making it difficult to measure all of the electrodes in a manufacturing process that requires productivity. In addition, the inter-electrode distance of the electrode body can vary inside the electrode depending on, for example, the state of the metal foil or the coating state of the active material layer, making it difficult to measure from the outside. The problem of dendrite precipitation is not limited to lithium ion secondary batteries, but is a common problem with non-aqueous electrolyte secondary batteries including sodium ion secondary batteries.

[0006] The present disclosed technology has been made in consideration of such problems, and has an object to provide a method for evaluating the inter-electrode distance of a non-aqueous electrolyte secondary battery, which can easily evaluate the suitability of the inter-electrode distance of an electrode assembly in a short time during the manufacturing stage of non-aqueous electrolyte secondary batteries, including lithium ion secondary batteries, and a method for manufacturing a non-aqueous electrolyte secondary battery using the inter-electrode distance evaluation method. [Means for solving the problem]

[0007] (1) One aspect of the disclosed technique for solving the above problems is a method for manufacturing a nonaqueous electrolyte secondary battery, the method comprising the steps of: housing, in a case, an electrode assembly in which a positive electrode body and a negative electrode body are stacked with a separator sandwiched therebetween; a nonaqueous electrolyte solution that has permeated between the electrodes of the electrode assembly; and an excess of the nonaqueous electrolyte solution that has not permeated between the electrodes of the electrode assembly; The method for evaluating the inter-electrode distance of a nonaqueous electrolyte secondary battery includes: an electrolyte injection step of injecting the nonaqueous electrolyte so that the surplus electrolyte remains in the case; a forced electrolyte penetration step of forcibly penetrating the surplus electrolyte in the case between the electrodes of the electrode body; a first liquid volume measurement step of measuring the liquid volume of the surplus electrolyte in the case after the electrolyte injection step and before the forced electrolyte penetration step; a second liquid volume measurement step of measuring the liquid volume of the surplus electrolyte in the case after the forced electrolyte penetration step; and an evaluation step of evaluating the inter-electrode distance of the electrode body as appropriate when an amount of change in liquid volume of the surplus electrolyte obtained by subtracting the liquid volume measured in the second liquid volume measurement step from the liquid volume measured in the first liquid volume measurement step is equal to or less than a predetermined reference value.

[0008] (2) In the method for evaluating the inter-electrode distance of a nonaqueous electrolyte secondary battery described in (1), the second liquid amount measuring step is preferably performed after the forced electrolyte penetration step, and after a conditioning step in which the nonaqueous electrolyte secondary battery is charged and discharged multiple times at room temperature and an aging step in which the battery is left at a high temperature for a predetermined period of time.

[0009] (3) Another aspect of the disclosed technique for solving the above problems is a method for manufacturing a nonaqueous electrolyte secondary battery using the method for evaluating an inter-electrode distance of a nonaqueous electrolyte secondary battery described in (1) or (2). [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view of a nonaqueous electrolyte secondary battery according to one embodiment of the present invention. [Diagram 2] 2 is a schematic perspective view showing a state in the middle of winding the positive electrode body and the negative electrode body of the electrode assembly shown in FIG. 1, with a separator sandwiched between them. FIG. [Diagram 3] 2 is a schematic cross-sectional view showing a laminated state of an electrode body in the present embodiment of a portion A shown in FIG. 1. [Figure 4] 2 is a schematic cross-sectional view showing a laminated state of an electrode body in a comparative example of part A shown in FIG. [Diagram 5]2 is a schematic cross-sectional view of a measuring device for measuring the amount of excess electrolyte in a case of the nonaqueous electrolyte secondary battery shown in FIG. 1 and an evaluation device for the interelectrode distance. [Figure 6] 6 is a schematic cross-sectional view showing a modified example of the measuring device shown in FIG. 5, in which the amount of excess electrolyte is measured while the nonaqueous electrolyte secondary battery is inclined. FIG. [Figure 7] 2 is a flow chart showing the steps of a method for evaluating the inter-electrode distance of the nonaqueous electrolyte secondary battery shown in FIG. 1. [Figure 8] 2 is a flow chart showing steps of a method for producing the nonaqueous electrolyte secondary battery shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Description of the Non-Aqueous Electrolyte Secondary Battery> Next, the configuration of a nonaqueous electrolyte secondary battery that is the subject of the method for evaluating the interelectrode distance according to the embodiment of the disclosed technology will be described in detail with reference to the drawings. FIG. 1 shows a schematic cross-sectional view of a nonaqueous electrolyte secondary battery according to one aspect of the present embodiment. FIG. 2 shows a schematic perspective view of the electrode body shown in FIG. 1 in the middle of being laminated and wound with a separator sandwiched therebetween. FIG. 3 shows a schematic cross-sectional view of the electrode body in this embodiment at part A shown in FIG. 1 in a laminated state. FIG. 4 shows a schematic cross-sectional view of the electrode body in a comparative example at part A shown in FIG. 1 in a laminated state.

[0012] 1 to 3, one embodiment (this embodiment) of the nonaqueous electrolyte secondary battery 10 is a nonaqueous electrolyte secondary battery 10 (10B) that contains, in a case 3, an electrode assembly 1 in which a positive electrode body 11 and a negative electrode body 12 are stacked with a separator 13 sandwiched therebetween, a nonaqueous electrolyte 2 that has permeated into the inter-electrode DK of the electrode assembly 1, and an excess electrolyte 2Y that is the same nonaqueous electrolyte 2 but has not permeated into the inter-electrode DK of the electrode assembly 1. There is no limitation on the type of this nonaqueous electrolyte secondary battery 10 (10B) (for example, a lithium ion secondary battery, a sodium secondary battery, etc.).

[0013] As shown in Fig. 1, the case 3 is made of, for example, an aluminum alloy, and is composed of a case body 31 having an opening 313, and a case lid 32 that seals the opening 313. Here, the case body 31 has a rectangular bottom plate 311 and a side plate 312 that stands vertically from the outer periphery of the bottom plate 311, and is formed by integral molding. The case lid 32 is formed as a rectangular plate, and an injection port 321 for injecting the electrolyte 2 and a safety valve 322 are formed near the center. The case body 31 and the case lid 32 do not have to be limited to the above shapes, and may be formed in various shapes.

[0014] Terminal insertion holes 323 are formed at both longitudinal ends of the case lid 32, and positive and negative current collector terminals 4 (41, 42) are coupled via insulating members 5 fitted into the terminal insertion holes 323. A positive external connection part 411 is formed at the upper end of the positive current collector terminal 41, and an internal connection part 412 electrically connected to the positive electrode body 11 of the electrode body 1 is formed at its lower end. A negative external connection part 421 is formed at the upper end of the negative current collector terminal 42, and an internal connection part 422 electrically connected to the negative electrode body 12 of the electrode body 1 is formed at its lower end.

[0015] As shown in FIG. 2 and FIG. 3, the electrode body 1 is formed by stacking the positive electrode body 11 and the negative electrode body 12 with the separator 13 sandwiched therebetween, and is wound in a flattened, pressure-bonded state. The electrode body 1 is not limited to a wound type electrode body, and may be, for example, a sheet-laminated type electrode body. The positive electrode body 11 is coated with a positive electrode active material layer 112 at a substantially constant thickness on both sides of the current collector foil (e.g., aluminum foil) 111, except for one end (non-coated portion). The negative electrode body 12 is coated with a negative electrode active material layer 122 at a substantially constant thickness on both sides of the current collector foil (e.g., copper foil) 121, except for one end (non-coated portion). The non-coated portion of the positive electrode body 11 is connected to an internal connection portion 412 of the positive electrode collector terminal 41, and the non-coated portion of the negative electrode body 12 is connected to an internal connection portion 422 of the negative electrode collector terminal 42.

[0016] Here, the inter-electrode distance DL of the electrode body 1 means the distance between the current collector foil 111 of the positive electrode body 11 and the current collector foil 121 of the negative electrode body 12, and Fig. 3 shows a state in which the positive electrode body 11, the separator 13, and the negative electrode body 12 are laminated with an appropriate inter-electrode distance DL1. The electrolyte 2 permeates the small gaps between the positive electrode active material layer 112, the separator 13, and the negative electrode active material layer 122, the minute gaps between the active materials of the active material layers 112, 122, and the pores of the separator 13. The separator 13 is bonded to the positive electrode active material layer 112 and the negative electrode active material layer 122 via an adhesive applied to allow charge carriers (e.g., lithium ions, etc., not shown) to pass through.

[0017] 3, when the positive electrode body 11, separator 13, and negative electrode body 12 are stacked with an appropriate interelectrode distance DL1, the internal resistance between the positive electrode body 11 and the negative electrode body 12 becomes substantially constant, the current flowing during charging and discharging is uniform, and localized overcharging is unlikely to occur. Therefore, in a nonaqueous electrolyte secondary battery (e.g., a lithium ion secondary battery), dendrites (e.g., metallic lithium) are unlikely to precipitate on the surface of the negative electrode body 12.

[0018] In contrast, when the positive electrode body 11, the separator 13, and the negative electrode body 12B are laminated with a partially wide interelectrode distance DL2, as in the electrode body 1B of the nonaqueous electrolyte secondary battery 10B of the comparative example shown in FIG. 4, the internal resistance between the positive electrode body 11 and the negative electrode body 12B becomes high in the region of the wide interelectrode distance DL2, and the current flowing during charging and discharging decreases. Meanwhile, in the convex region HP at the distance change point of the interelectrode distance DL2, local overcharging is likely to occur, and dendrites (e.g., metallic lithium) are likely to precipitate in the convex region HP of the negative electrode body 12B. This region of the partially wide interelectrode distance DL2 can occur during the manufacturing stage of the electrode body 1B due to deformation of the negative electrode current collector foil 121B of the electrode body 1B, variation in the coating thickness of the negative electrode active material layer 122B, and the like. Therefore, in order to provide a high-quality nonaqueous electrolyte secondary battery 10 that is highly resistant to precipitation of dendrites (e.g., metallic lithium), it is important to evaluate whether there are many regions with a relatively wide inter-electrode distance DL during the manufacturing stage of the nonaqueous electrolyte secondary battery 10.

[0019] The nonaqueous electrolyte secondary batteries 10 and 10B are not limited to a specific type (e.g., a lithium ion secondary battery, a sodium secondary battery, etc.); however, the positive electrode active material layer 112, the separator 13, the negative electrode active material layer 122, and the electrolyte 2 differ depending on the type of the nonaqueous electrolyte secondary battery 10, and any known materials may be used.

[0020] <Method for evaluating the electrode distance of the non-aqueous electrolyte secondary battery> Hereinafter, a method for evaluating the inter-electrode distance of a non-aqueous electrolyte secondary battery, which can easily evaluate in a short time whether the inter-electrode distance of the electrode body involved in the above-mentioned dendrite precipitation is appropriate during the manufacturing stage of the non-aqueous electrolyte secondary battery, will be described with reference to Figs. 1 to 7. Fig. 5 shows a schematic cross-sectional view of a measuring device for measuring the amount of excess electrolyte in the case of the non-aqueous electrolyte secondary battery shown in Fig. 1 and an evaluation device for the inter-electrode distance. Fig. 6 shows a schematic cross-sectional view of a modified example of the measuring device shown in Fig. 5, in which the amount of excess electrolyte is measured with the non-aqueous electrolyte secondary battery inclined. Fig. 7 shows a flow chart showing the steps in the evaluation method for the inter-electrode distance of the non-aqueous electrolyte secondary battery shown in Fig. 1.

[0021] As shown in FIGS. 1 to 7 , the evaluation method SS for the inter-electrode distance DL of the non-aqueous electrolyte secondary battery 10 (10B) includes the following steps during the production of a non-aqueous electrolyte secondary battery 10 in which an electrode body 1 in which a positive electrode body 11 and a negative electrode body 12 are stacked with a separator 13 sandwiched between them, a non-aqueous electrolyte 2 that has permeated into the inter-electrode DK of the electrode body 1, and a surplus electrolyte 2Y of the non-aqueous electrolyte 2 that has not permeated into the inter-electrode DK of the electrode body 1 are housed in a case 3.

[0022] That is, the evaluation method SS for the inter-electrode distance DL of the nonaqueous electrolyte secondary battery 10 includes: (a) an electrolyte injection step S1 for injecting the nonaqueous electrolyte 2 so that excess electrolyte 2Y remains in the case 3; (b) a forced electrolyte penetration step S3 for forcibly infiltrating the excess electrolyte 2Y in the case 3 into the inter-electrode distance DK of the electrode body 1; and (c) measuring the amount L0 of the excess electrolyte 2Y in the case 3 after the electrolyte injection step S1 and before the forced electrolyte penetration step S3. The method includes (d) a first liquid volume measurement process S2, (e) a second liquid volume measurement process S4 for measuring the liquid volume L1 of the excess electrolyte 2Y in the case 3 after the forced electrolyte penetration process S3, and (f) an evaluation process S5 for evaluating that the inter-electrode distance DL of the electrode body 1 is appropriate if the liquid change amount ΔL of the excess electrolyte 2Y, which is obtained by subtracting the liquid volume L1 measured in the second liquid volume measurement process S4 from the liquid volume L0 measured in the first liquid volume measurement process S2, is equal to or less than a predetermined reference value KJ.

[0023] (a) In the electrolyte injection step S1, an electrolyte discharge nozzle (not shown) is inserted between the upper end of the electrode body 1 housed in the case 3 and the case cover 32 through the injection port 321 of the case cover 32, and a required amount of nonaqueous electrolyte 2 is injected from the electrolyte discharge nozzle into the case 3. At this stage, part of the injected nonaqueous electrolyte 2 permeates into the inter-electrode DK on the outer periphery side of the electrode body 1, but is unlikely to permeate into the inter-electrode DK on the inner periphery side of the electrode body 1, and excess electrolyte 2Y that does not permeate into the inter-electrode DK of the electrode body 1 remains in the case 3.

[0024] (b) In the electrolyte forced permeation step S3, the excess electrolyte 2Y in the case 3 is forced to permeate the gap DK of the electrode body 1. At this time, the excess electrolyte 2Y in the case 3 decreases more as the number of regions with a wide interelectrode distance DL on the inner periphery side of the electrode body 1 increases. Therefore, the larger the liquid change amount ΔL of the excess electrolyte 2Y in the case 3, the more regions with a wide interelectrode distance DL on the inner periphery side of the electrode body 1, and the lower the resistance to dendrite (e.g., lithium metal) precipitation. The method of forcibly permeating the excess electrolyte 2Y into the gap DK of the electrode body 1 is not particularly limited, but includes, for example, a method of increasing or decreasing the internal pressure of the case 3 to permeate the excess electrolyte 2Y by a pressure difference, or a method of vibrating the case 3 to permeate the excess electrolyte 2Y by inertial force.

[0025] (c) In a first liquid volume measurement step S2, after the electrolyte injection step S1 and before the electrolyte forced permeation step S3, the liquid volume L0 of the excess electrolyte 2Y in the case 3 is measured. Also, in a (d) second liquid volume measurement step S4, after the electrolyte forced permeation step S3, the liquid volume L1 of the excess electrolyte 2Y in the case 3 is measured. Unlike CT image analysis, the liquid volumes L0 and L1 can be measured easily in a short time during the manufacturing stage of the nonaqueous electrolyte secondary battery 10 to match the takt time (for example, a few dozen seconds) of the manufacturing line.

[0026] The measuring device 6 used in the first liquid amount measuring step S2 and the second liquid amount measuring step S4 includes, for example, a fluoroscopic line emitting device 61, a fluoroscopic image measuring device 62, and a table device 63 on which the nonaqueous electrolyte secondary battery 10 (10B) to be measured is placed, as shown in Fig. 5. Here, the fluoroscopic line emitting device 61 is a device (e.g., an X-ray emitting device) that emits a fluoroscopic line 64 that allows the inside of the nonaqueous electrolyte secondary battery 10 (10B) to be seen through. The fluoroscopic image measuring device 62 is a device that measures the liquid amounts L0 and L1 of the excess electrolyte 2Y by the following formulas (1) and (2) from the liquid level heights H1, H2, etc. of the excess electrolyte 2Y relative to the bottom plate 311 of the case main body 31, which are measured based on the fluoroscopic image of the fluoroscopic line 64, and the volumes R1 and R2 of the electrode body 1 present below the liquid level of the excess electrolyte 2Y. L0 = H1 × D1 × D2 - R1 Formula (1) L1 = H2 × D1 × D2 - R2 Formula (2)

[0027] In addition, D1 is the longitudinal length of the bottom plate 311 of the case body 31, D2 is the transverse length of the bottom plate 311 of the case body 31, R1 is the volume of the electrode body 1 present below the liquid surface of the excess electrolyte 2Y measured in the first liquid volume measurement process S2, and R2 is the volume of the electrode body 1 present below the liquid surface of the excess electrolyte 2Y measured in the second liquid volume measurement process S4.

[0028] (e) In the evaluation step S5, when the amount of change in the liquid volume ΔL of the excess electrolyte 2Y, which is obtained by subtracting the amount of liquid volume L1 measured in the second liquid volume measurement step S4 from the amount of liquid volume L0 measured in the first liquid volume measurement step S2, is equal to or less than a predetermined reference value KJ, the inter-electrode distance DL of the electrode body 1 is evaluated as being appropriate. The evaluation device 7 used in this evaluation step S5 is connected to the measurement device 6 (fluoroscopic image measurement device 62). The evaluation device 7 includes, for example, a calculation circuit 71 that determines the amount of change in liquid volume ΔL of the excess electrolyte 2Y from the difference (L0-L1) between the liquid volume L0 of the excess electrolyte 2Y measured in the first liquid volume measurement process S2 and the liquid volume L1 of the excess electrolyte 2Y measured in the second liquid volume measurement process S4, an input / storage circuit 72 that inputs a predetermined reference value KJ and stores the input reference value KJ, and a judgment circuit 73 that compares the amount of change in liquid volume ΔL with the reference value KJ to judge whether the inter-electrode distance DL of the electrode body 1 is appropriate or inappropriate.

[0029] The reference value KJ is set to a value of the amount of solution change that provides good resistance to dendrite (e.g., lithium metal) precipitation depending on the type, form, battery capacity, etc. of the nonaqueous electrolyte secondary battery 10. For example, it is known that the resistance to dendrite (e.g., lithium metal) precipitation is good when the ratio (capacity maintenance rate) of the discharge capacity after a high-rate charge-discharge test to the discharge capacity after a conditioning step S6 described below is 90% or more. Therefore, for example, the value of the amount of solution change ΔL when the capacity maintenance rate is 90% or more can be set as the reference value KJ.

[0030] In addition, when the amount of the excess electrolyte 2Y in the case 3 is small, it is preferable to measure the amount of the excess electrolyte 2Y in a state where the case 3 is inclined so that the excess electrolyte 2Y of the nonaqueous electrolyte secondary battery 10 (10B) gathers at one case corner 314 as shown in FIG. 6. In this case, the mounting surface of the table device 63B on which the bottom plate 311 of the case 3 is mounted is formed as an inclined surface that opens upward in a V shape (for example, an inclination angle θ=45°). Then, with the bottom plate 311 and the side plate 312 of the case 3 mounted on the inclined surface, the fluoroscopic line irradiation device 61 shown in FIG. 5 irradiates a fluoroscopic line 64 from the normal direction of the drawing, and the fluoroscopic image measurement device 62 measures based on the fluoroscopic image of the fluoroscopic line 64. In this case, the amounts L0 and L1 of the excess electrolyte 2Y can be accurately measured by the following formulas (3) and (4). L0 = 1 / 2 × H1 × W1 × D2 - T1 Formula (3) L1 = 1 / 2 × H2 × W2 × D2 - T2 Formula (4)

[0031] Here, W1 is the length of the surface of the excess electrolyte 2Y measured in the first liquid volume measurement step S2, W2 is the length of the surface of the excess electrolyte 2Y measured in the second liquid volume measurement step S4, T1 is the volume of the electrode body 1 present below the surface of the excess electrolyte 2Y measured in the first liquid volume measurement step S2, and T2 is the volume of the electrode body 1 present below the surface of the excess electrolyte 2Y measured in the second liquid volume measurement step S4. Also, D2 is the short-side length of the bottom plate 311 of the case body 31.

[0032] 7, in the evaluation method SS for the interelectrode distance DL of the nonaqueous electrolyte secondary battery 10, the second liquid amount measurement step S4 is preferably performed after the electrolyte forced penetration step S3 and after a conditioning step S6 in which the nonaqueous electrolyte secondary battery 10 is charged and discharged multiple times at room temperature and an aging step S7 in which the battery is left at a high temperature for a predetermined time. In the conditioning step S6, a protective coating 12H (see FIG. 3) derived from the electrolyte 2 can be formed near the surface of the negative electrode body 12 by repeating charging and discharging multiple times at room temperature. In the aging step S7, the battery is left at a high temperature for a predetermined time, whereby metal foreign matter can be dissolved and the protective coating 12H can be stabilized. In this case, the excess electrolyte 2Y in the case 3 decreases slightly due to the expansion and contraction of the electrode body 1 and the formation of the protective coating 12H that occur during the conditioning process S6 and the aging process S7, so that the appropriateness of the inter-electrode distance DL of the electrode body 1 can be determined based on the more accurate liquid change amount ΔL of the excess electrolyte 2Y.

[0033] <Manufacturing method of non-aqueous electrolyte secondary battery using electrode distance evaluation method> Next, a method for manufacturing a nonaqueous electrolyte secondary battery using the above-mentioned method for evaluating the interelectrode distance will be described with reference to Fig. 8. Fig. 8 shows a flow chart illustrating the steps in the method for manufacturing the nonaqueous electrolyte secondary battery shown in Fig. 1.

[0034] The manufacturing method for the nonaqueous electrolyte secondary battery 10 uses the above-mentioned evaluation method SS for the inter-electrode distance DL of the nonaqueous electrolyte secondary battery 10. That is, as shown in Fig. 8, the manufacturing method for the nonaqueous electrolyte secondary battery 10 sequentially performs a battery assembly step Q1, an electrolyte injection step S1, a first liquid level measurement step S2, an electrolyte forced penetration step S3, an initial charging step Q2, a conditioning step S6, an aging step S7, a second liquid level measurement step S4, an evaluation step S5, and an appearance inspection step Q3.

[0035] Here, the battery assembly process Q1 is a process of housing the electrode body 1, in which the positive electrode body 11 and the negative electrode body 12 are stacked with the separator 13 sandwiched therebetween, in the case body 31 and sealing the case lid 32. At this stage, the injection port 321 for the electrolyte 2 is open. The initial charging process Q2 is a process of connecting the electrode body 1 to an external power source to perform an initial charge, and releasing gas generated by decomposition of part of the electrolyte and moisture contained in the battery to the outside of the case. The appearance inspection process Q3 is a process of inspecting for scratches and the like on the appearance and deciding whether or not to ship the battery.

[0036] Then, the nonaqueous electrolyte secondary battery 10 in which the inter-electrode distance DL of the electrode body 1 is evaluated as appropriate in the evaluation step S5 is sent to the appearance inspection step Q3, and is shipped if the appearance inspection passes (OK). In contrast, the nonaqueous electrolyte secondary battery 10 in which the inter-electrode distance DL of the electrode body 1 is evaluated as inappropriate in the evaluation step S5 is suspended from shipment. Also, even if the nonaqueous electrolyte secondary battery 10 in which the inter-electrode distance DL of the electrode body 1 is evaluated as appropriate in the evaluation step S5 is not passed (NG) in the appearance inspection step Q3, shipment is suspended.

[0037] As described above, the manufacturing method for the nonaqueous electrolyte secondary battery 10 uses the evaluation method SS for the inter-electrode distance DL of the nonaqueous electrolyte secondary battery 10 in the manufacturing process of the nonaqueous electrolyte secondary battery 10, and therefore can evaluate the suitability of the inter-electrode distance DL of the electrode body 1 involved in dendrite precipitation for all nonaqueous electrolyte secondary batteries 10. Therefore, it is possible to stably provide high-quality nonaqueous electrolyte secondary batteries with excellent dendrite precipitation resistance.

[0038] <Modification> The above-described embodiment is merely an example and does not limit the disclosed technology in any way. Therefore, the disclosed technology can be improved or modified in various ways without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0039] 1 Electrode body 2 Non-aqueous electrolyte 2Y Surplus electrolyte 3 Cases 10, 10B non-aqueous electrolyte secondary battery 11 Cathode 12 Negative electrode body 13 Separator DK Polar DL distance between poles KJ Standard Value L0, L1 liquid volume ΔL Fluid change amount S1 Electrolyte injection process S2 First liquid volume measurement process S3 Forced electrolyte penetration process S4 Second liquid volume measurement process S5 Evaluation process S6 Conditioning process S7 Aging process

Claims

1. In a manufacturing process of a non-aqueous electrolyte secondary battery, an electrode assembly in which a positive electrode body and a negative electrode body are laminated with a separator sandwiched therebetween, a non-aqueous electrolyte that has permeated between the electrodes of the electrode assembly, and an excess of the non-aqueous electrolyte that has not permeated between the electrodes of the electrode assembly are housed in a case, an electrolyte injection step of injecting the nonaqueous electrolyte so that excess electrolyte remains in the case; an electrolyte forced penetration step of forcibly penetrating the excess electrolyte in the case between the electrodes of the electrode body; a first liquid amount measuring step of measuring the amount of the excess electrolyte in the case after the electrolyte injection step and before the electrolyte forced penetration step; a second liquid amount measuring step of measuring the amount of the excess electrolyte in the case after the electrolyte forced penetration step; and an evaluation step of evaluating the inter-electrode distance of the electrode body as appropriate when a change in the amount of the excess electrolyte, which is obtained by subtracting the amount of the electrolyte measured in the second liquid volume measurement step from the amount of the electrolyte measured in the first liquid volume measurement step, is equal to or less than a predetermined reference value. A method for evaluating the interelectrode distance of a non-aqueous electrolyte secondary battery.

2. The method for evaluating the inter-electrode distance of a nonaqueous electrolyte secondary battery according to claim 1, The second liquid amount measuring step is performed after the electrolyte forced penetration step, and after a conditioning step in which the nonaqueous electrolyte secondary battery is charged and discharged multiple times at room temperature and an aging step in which the battery is left at a high temperature for a predetermined period of time. A method for evaluating the interelectrode distance of a non-aqueous electrolyte secondary battery.

3. The method for evaluating the electrode distance of a non-aqueous electrolyte secondary battery according to claim 1 or 2 is used. A method for manufacturing a non-aqueous electrolyte secondary battery.

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