Manufacturing method for non-aqueous secondary batteries

Abstract

To provide a method for manufacturing a nonaqueous secondary battery that suppresses deposition of Li due to formation of a NaBOB film.SOLUTION: A method for manufacturing a nonaqueous secondary battery having a positive electrode sheet, a negative electrode sheet, and a nonaqueous electrolyte having a film forming material containing a lithium salt, includes: a measurement process S2 for measuring an amount of sodium of sodium salt contained in an electrode body before injection of a nonaqueous electrolyte; and an infiltration process S6 for infiltrating the nonaqueous electrolyte into the positive electrode sheet and the negative electrode sheet at infiltration temperature determined based on the measured amount of sodium.SELECTED DRAWING: Figure 3

Description

Technical Field

[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, after accommodating an electrode body in a battery case, before injecting an electrolytic solution containing an additive into the battery case, a heating press process is performed in which the battery case accommodating the electrode body is heated while applying a load in the thickness direction of the electrode body to restrain it. The heating press process is performed so that the temperature of the electrode body becomes 80 to 110°C. Further, the temperature of the electrolytic solution at the time of liquid injection is within the range of 20 to 30°C, and the temperature of the electrode body is within the range of 35 to 50°C.

Prior Art Documents

Patent Documents

[0003]

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 the above Patent Document 1, a film-forming material containing lithium is added to the non-aqueous electrolytic solution. The film-forming material 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. And 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, resulting in Li precipitation. Suppression of Li precipitation due to the formation of the NaBOB film is required.

Means for Solving the Problems

[0005] A method for manufacturing a non-aqueous secondary battery that solves the above problems is a method for manufacturing a non-aqueous secondary battery having a positive electrode sheet, a negative electrode sheet, and a non-aqueous electrolyte containing a film-forming material containing a lithium salt, comprising: a measurement step of measuring the amount of sodium in the sodium salt contained in the electrode body before injecting the non-aqueous electrolyte; and an impregnation step of impregnating the positive electrode sheet and the negative electrode sheet with the non-aqueous electrolyte at an impregnation temperature determined based on the measured amount of sodium.

[0006] According to the above configuration, the penetration temperature for permeating the non-aqueous electrolyte into the positive and negative electrode sheets is determined based on the measured amount of sodium. For example, if the amount of sodium is high, lowering the penetration temperature can suppress the formation of localized NaBOB, thereby improving precipitation resistance. Conversely, if the amount of sodium is low, raising the penetration temperature improves the permeability of the non-aqueous electrolyte, leading to a more uniform coating and thus improving precipitation resistance. Increasing the penetration temperature also shortens the penetration time, thus improving productivity.

[0007] In the above method for manufacturing a non-aqueous secondary battery, it is preferable to include an injection step, prior to the infiltration step, in which the non-aqueous electrolyte is injected at an injection temperature determined based on the measured amount of sodium.

[0008] According to the above configuration, the injection temperature for injecting the non-aqueous electrolyte is determined based on the measured amount of sodium. For example, if the amount of sodium is high, lowering the injection temperature can suppress the formation of localized NaBOB, thereby improving precipitation resistance. Conversely, if the amount of sodium is low, raising the injection temperature improves the permeability of the non-aqueous electrolyte, leading to a more uniform coating and thus improving precipitation resistance. Increasing the injection temperature also shortens the penetration time, thus improving productivity.

[0009] In the above method for manufacturing a non-aqueous secondary battery, it is preferable that the permeation temperature determined in the permeation step has a negative correlation with the amount of sodium. According to the above configuration, by determining the penetration temperature in the penetration process to have a negative correlation with the amount of sodium, it is possible to suppress Li precipitation due to the formation of a NaBOB film.

[0010] In the above method for manufacturing a non-aqueous secondary battery, it is preferable that the injection temperature determined in the injection step has a negative correlation with the amount of sodium. According to the above configuration, by determining the injection temperature in the injection process to have a negative correlation with the amount of sodium, it is possible to suppress Li precipitation due to the formation of a NaBOB film.

[0011] Regarding the method for manufacturing the non-aqueous secondary battery described above, it is preferable that the film-forming material is LiBOB (lithium bisoxalate borate). According to the above configuration, the coating material is LiBOB. Therefore, LiBOB can form a relatively stable coating on the negative electrode sheet that can extend the battery life. [Effects of the Invention]

[0012] According to the present invention, it is possible to suppress Li precipitation due to the formation of a NaBOB film. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view showing the general configuration of a cell in a non-aqueous secondary battery. [Figure 2] This is a diagram showing a portion of the electrode body unfolded. [Figure 3] This is a flowchart showing a method for manufacturing a non-aqueous secondary battery. [Figure 4] This figure shows the diffusion of Na and BOB during the infiltration process of a non-aqueous secondary battery. [Figure 5] This figure shows the diffusion of Na and BOB during the infiltration process of a non-aqueous secondary battery. [Figure 6] This figure shows the diffusion of Na and BOB during the infiltration process of a non-aqueous secondary battery. [Figure 7]It is a diagram showing the diffusion of Na and BOB in the penetration process of a non-aqueous secondary battery. [Figure 8] It is a table showing the implementation conditions of examples and comparative examples of the method for manufacturing a non-aqueous secondary battery. [Figure 9] It is a graph showing examples and comparative examples of the method for manufacturing a non-aqueous secondary battery. [Figure 10] It is a table showing the results of examples and comparative examples of the method for manufacturing a non-aqueous secondary battery.

Mode for Carrying Out the Invention

[0014] Hereinafter, referring to FIGS. 1 to 10, an embodiment of the method for manufacturing a non-aqueous secondary battery will be described. As an example of the non-aqueous secondary battery, a lithium-ion secondary battery will be described. [Lithium-ion secondary battery 10]

[0015] As shown in FIG. 1, the lithium-ion secondary battery 10 is a cell battery that is enclosed in a resin or metal case in a state combined with a plurality of lithium-ion secondary batteries 10 to form a battery pack. The battery pack is used in a hybrid vehicle or an electric vehicle.

[0016] The lithium-ion secondary battery 10 includes a battery case 11 and a lid 12. The battery case 11 has a rectangular parallelepiped shape with an opening on the upper side. The lid 12 seals the opening of the battery case 11. The battery case 11 and the lid 12 are made of a metal such as aluminum or an aluminum alloy. The lithium-ion secondary battery 10 forms a sealed battery tank by attaching the lid 12 to the battery case 11.

[0017] The lid body 12 is provided with two positive electrode external terminals 13A and a negative electrode external terminal 13B. The positive electrode external terminal 13A and the negative electrode external terminal 13B are used for charging and discharging of electric power. Inside the battery case 11, an electrode body 20 is accommodated. A positive electrode current collecting portion 20A, which is an end portion on the positive electrode side of the electrode body 20, is electrically connected to the positive electrode external terminal 13A via a positive electrode current collecting member 14A. A negative electrode current collecting portion 20B, which is an end portion on the negative electrode side of the electrode body 20, is electrically connected to the negative electrode external terminal 13B via a negative electrode current collecting member 14B. Further, 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.

[0018] [Electrode body 20] As shown in FIG. 2, the electrode body 20 is a flat wound 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 longitudinal direction of each 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.

[0019] [Positive electrode sheet 21] The positive electrode sheet 21 includes a positive electrode current collector 22 and a positive electrode mixture layer 23. The positive electrode current collector 22 is a foil-shaped electrode base material formed in a long shape. The positive electrode mixture 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 where the positive electrode current collector 22 is exposed without the formation of the positive electrode mixture layer 23 at one end in the width direction D2.

[0020] The positive electrode current collector 22 is formed of a metal foil made 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 constitutes the positive electrode side current collecting portion 20A with the opposing surfaces being pressed against each other in the state of the wound body.

[0021] The positive electrode composite layer 23 is a cured form of a liquid positive electrode composite paste. The positive electrode composite 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 layer 23 is formed when the positive electrode composite paste dries and the positive electrode solvent vaporizes. Therefore, the positive electrode composite layer 23 contains a positive electrode active material, a positive electrode conductive material, and a positive electrode binder.

[0022] The positive electrode active material is a lithium-containing composite oxide capable of intercalating 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 metallic elements other than lithium. The other metallic 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.

[0023] 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).

[0024] 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 composite paste. Examples of positive electrode binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and styrene-butadiene rubber (SBR).

[0025] 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.

[0026] [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 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 uncoated portion 25A at one end in the width direction D2, which is located opposite the positive electrode uncoated portion 22A, where the negative electrode composite layer 26 is not formed and the negative electrode current collector 25 is exposed.

[0027] 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 wound state, the unpainted negative electrode side portion 25A has opposing surfaces pressed against each other to form the negative electrode side current collector portion 20B.

[0028] 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 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 is dried and the negative electrode solvent vaporizes. Therefore, the negative electrode composite layer 26 contains the negative electrode active material, 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.

[0029] 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, easily graphitizable carbon, and carbon nanotubes. The negative electrode solvent is, for example, water. 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, SBR (styrene-butadiene copolymer) can be used as a binder containing a sodium salt.

[0030] [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 electrode body 20 is immersed in the non-aqueous electrolyte, the non-aqueous electrolyte permeates from the edges of the separator 27 toward the center.

[0031] The separator 27 is a nonwoven fabric made of polypropylene or the like. As the separator 27, for example, porous polymer membranes such as porous polyethylene membranes, porous polyolefin membranes, and porous polyvinyl chloride membranes, and ion-conductive polymer electrolyte membranes can be used.

[0032] [Nonaqueous electrolyte] A 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.

[0033] In this embodiment, ethylene carbonate is used as the non-aqueous solvent. LiBOB (lithium bisoxalate borate) is added to the non-aqueous electrolyte as a lithium salt additive. For example, LiBOB is added to the non-aqueous electrolyte so that the concentration of LiBOB in the non-aqueous electrolyte is between 0.001 and 0.1 [mol / L].

[0034] [Manufacturing method] Next, with reference to Figure 3, a method for manufacturing the lithium-ion secondary battery 10 will be described. In this manufacturing method, the amount of sodium contained in the electrode body 20 is estimated before the non-aqueous electrolyte is injected, and the temperature of the non-aqueous electrolyte and the permeation temperature during permeation are changed based on the amount of sodium.

[0035] In step S1, the electrode plate manufacturing process, a positive electrode sheet 21 as the positive electrode plate and a negative electrode sheet 24 as the negative electrode plate are created. The positive electrode sheet 21 comprises a positive electrode current collector 22 and a positive electrode composite layer 23. The positive electrode current collector 22 is a foil-shaped electrode substrate formed in a long, rectangular shape. The positive electrode composite layer 23 is provided on each of two opposing surfaces of the positive electrode current collector 22. The positive electrode composite layer 23 is a cured form of a liquid positive electrode composite paste. The positive electrode composite 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 layer 23 is formed when the positive electrode composite paste dries and the positive electrode solvent vaporizes.

[0036] 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 electrode substrate formed in a long, rectangular 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 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 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.

[0037] In the measurement process of step S2, the amount of sodium in the sodium salt contained in the electrode body 20 is measured. The amount of sodium in the electrode body 20 is determined by measuring the amount of sodium in the positive electrode sheet 21, the negative electrode sheet 24, and the separator 27, respectively. It is desirable to perform the measurement for each lot of material.

[0038] The amount of sodium contained in the material can be measured, for example, by inductively coupled plasma (ICP), a technique of emission spectroscopy. However, any method that can measure the amount of sodium contained in the material is acceptable.

[0039] In the winding process of step S3, the positive electrode sheet 21 and the negative electrode sheet 24 are laminated with a separator 27 in between. The laminate of the positive electrode sheet 21 and the negative electrode sheet 24, laminated with the separator 27 in between, is wound up. Subsequently, the laminated and wound up body of the positive electrode sheet 21, the negative electrode sheet 24, and the separator 27 is pressed flat. Thus, the outer shape of the electrode body 20 is formed on the wound up body composed of the positive electrode sheet 21, the negative electrode sheet 24, and the separator 27.

[0040] In the insertion process of step S4, the electrode body 20 is inserted into the battery case 11. Once the electrode body 20 is inserted into the battery case 11, the opening of the battery case 11 is sealed by the cover body 12.

[0041] In the injection process of step S5, a non-aqueous electrolyte is injected into the battery case 11 containing the electrode body 20 through the injection hole. At this time, the non-aqueous electrolyte is injected into the battery case 11 at an injection temperature determined based on the measured amount of sodium, such that the injection temperature is lower when the amount of sodium is high in the measurement process. The non-aqueous electrolyte is injected after its temperature reaches the injection temperature. The injection temperature determined in the injection process has a negative correlation with the amount of sodium. That is, when the amount of sodium contained in the electrode body 20 is high, lowering the injection temperature can suppress the formation of localized NaBOB, thereby improving precipitation resistance. Also, when the amount of sodium contained in the electrode body 20 is low, raising the injection temperature improves the permeability of the non-aqueous electrolyte, which improves precipitation resistance by homogenizing the coating. When the injection temperature is increased, the permeation time is shortened, which can improve productivity.

[0042] In the permeation process of step S6, the non-aqueous electrolyte is permeated into the positive electrode sheet 21 and the negative electrode sheet 24. At this time, the non-aqueous electrolyte is permeated into the positive electrode sheet 21 and the negative electrode sheet 24 at a permeation temperature determined based on the measured amount of sodium, such that the permeation temperature is lowered as the amount of sodium increases in the measurement process. The permeation process is performed with the ambient temperature of the room where the permeation process is carried out set as the permeation temperature. The permeation temperature determined in the permeation process has a negative correlation with the amount of sodium. That is, if the amount of sodium contained in the electrode body 20 is large, the formation of localized NaBOB can be suppressed by lowering the permeation temperature, thereby improving precipitation resistance. Also, if the amount of sodium contained in the electrode body 20 is small, raising the permeation temperature improves the permeability of the non-aqueous electrolyte and improves precipitation resistance by homogenizing the coating. When the permeation temperature is increased, the permeation time is shortened, so productivity can be improved.

[0043] In the activation process of step S7, the lithium-ion secondary battery 10 is charged and discharged multiple times. This allows the lithium-ion secondary battery 10 to discharge smoothly to a predetermined capacity. Thus, the lithium-ion secondary battery 10 is manufactured.

[0044] [diffusion] Next, the diffusion of Na ions and BOB ions in the above penetration process will be explained with reference to Figures 4 to 7. LiBOB is added as an additive to the non-aqueous electrolyte, and sodium is contained in the electrode body 20. In Figures 4 to 7, Na ions are shown by solid lines, and BOB ions are shown by dashed lines.

[0045] First, as shown in Figure 4, Na ions diffuse rapidly in non-aqueous electrolytes. On the other hand, BOB ions diffuse slowly in non-aqueous electrolytes. Therefore, a difference in diffusion rates occurs between Na ions and BOB ions in the initial stages of osmosis.

[0046] Next, as shown in Figure 5, the Na ions concentrate in the center before attempting to penetrate the electrode body 20 at a constant rate. At this time, if the temperature of the non-aqueous electrolyte is high, the viscosity of the non-aqueous electrolyte decreases, and the difference in diffusion rates between Na ions and BOB ions becomes larger. Therefore, the Na ions concentrate in the center more quickly.

[0047] Next, as shown in Figure 6, BOB ions cannot overcome areas with high Na ion concentrations, and NaBOB is generated in these high-concentration Na ion regions (localized NaBOB generation). It is presumed that this localized NaBOB generation is more frequent in conventional techniques due to the high temperatures involved.

[0048] On the other hand, as shown in Figure 7, when the temperature of the non-aqueous electrolyte is low, the viscosity of the non-aqueous electrolyte increases, and the difference in diffusion rates between Na ions and BOB ions decreases. Therefore, BOB ions can catch up with Na ions before they concentrate in the center, suppressing localized NaBOB formation. In this way, suppression of NaBOB formation is expected to improve resistance to Li precipitation. Furthermore, if the amount of Na is low and there is no concern about NaBOB formation, productivity can also be improved, and both performance and productivity can be balanced depending on the amount of sodium contained in the electrode body 20.

[0049] Next, the effects of this embodiment will be described. (1) Based on the measured amount of sodium, the penetration temperature for permeating the non-aqueous electrolyte into the positive and negative electrode sheets is determined. For example, if the amount of sodium is high, lowering the penetration temperature can suppress the formation of localized NaBOB, thereby improving precipitation resistance. If the amount of sodium is low, raising the penetration temperature improves the permeability of the non-aqueous electrolyte, which in turn improves precipitation resistance by making the coating more uniform. When the penetration temperature is increased, the penetration time is shortened, which can improve productivity.

[0050] (2) The injection temperature for injecting the non-aqueous electrolyte is determined based on the measured amount of sodium. For example, if the amount of sodium is high, lowering the injection temperature can suppress the formation of localized NaBOB, thereby improving precipitation resistance. If the amount of sodium is low, raising the injection temperature improves the permeability of the non-aqueous electrolyte, which can improve precipitation resistance by making the coating more uniform. When the injection temperature is increased, the penetration time is shortened, which can improve productivity.

[0051] (3) By determining the penetration temperature in the penetration process to have a negative correlation with the amount of sodium, the deposition of Li due to the formation of the NaBOB film can be suppressed. (4) By determining the injection temperature in the injection process to have a negative correlation with the amount of sodium, the deposition of Li due to the formation of a NaBOB film can be suppressed.

[0052] (5) The coating material is LiBOB. Therefore, LiBOB can form a relatively stable coating on the negative electrode sheet that can extend the battery life.

[0053] [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.

[0054] In the above embodiment, the injection temperature in the injection process and the permeation temperature in the permeation process were changed based on the measured amount of sodium. However, only the permeation temperature in the permeation process may be changed based on the measured amount of sodium.

[0055] In the above embodiment, the negative electrode thickener added to the negative electrode mixture is not limited to CMC as long as it contains a sodium salt. In the above embodiment, the LiBOB used as a film-forming material added to the non-aqueous electrolyte is not particularly limited as long as it contains a lithium salt.

[0056] In the above embodiment, the negative electrode binder added to the negative electrode mixture is not limited to SBR as long as it contains a sodium salt. In the above embodiment, the electrode body 20 was formed by winding a laminate in which a positive electrode sheet 21 and a negative electrode sheet 24 were stacked with a separator 27 in between. However, the electrode body may also be formed by stacking multiple positive electrode sheets 21 and multiple negative electrode sheets 24 alternately with a separator 27 in between.

[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.

[0058] [Examples] Next, examples and comparative examples of lithium-ion secondary battery 10 will be described with reference to Figures 8 to 10. Note that these examples and comparative examples do not limit the manufacturing method of non-aqueous secondary batteries.

[0059] In the following, as shown in Figures 8 and 9, lithium-ion secondary batteries 10 of examples and comparative examples were prepared by changing the combination of the amount of sodium contained in the electrode body 20 and the permeation temperature. For each example and comparative example, the uniformity of resistance, Li deposition resistance, and the time until the resistance became constant by AC-IR were evaluated.

[0060] [Example 1] The amount of sodium contained in electrode 20 was set to 0.02 mg. The osmosis temperature was set to 25°C. The injection temperature was also set to 25°C.

[0061] [Example 2] The amount of sodium contained in electrode 20 was set to 0.05 mg. The osmosis temperature was set to 13°C. The injection temperature was also set to 13°C. Since Example 2 has a larger amount of sodium than Example 1, the osmosis temperature and injection temperature were set lower than in Example 1.

[0062] [Example 3] The amount of sodium contained in electrode 20 was set to 0.1 mg. The osmosis temperature was set to 2°C. The injection temperature was also set to 2°C. Since Example 3 contains a larger amount of sodium than Examples 1 and 2, the osmosis temperature and injection temperature were set lower than in Examples 1 and 2.

[0063] [Comparative Example 1] The amount of sodium contained in electrode 20 was set to 0.02 mg. The osmosis temperature was set to 2°C. The injection temperature was also set to 2°C.

[0064] [Comparative Example 2] The amount of sodium contained in electrode 20 was set to 0.1 mg. The osmosis temperature was set to 25°C. The injection temperature was also set to 25°C.

[0065] [evaluation] As shown in Figure 10, for each of the above examples and comparative examples, the uniformity of resistance, Li deposition resistance, and the time it took for the resistance to become constant using AC-IR were evaluated. Resistance uniformity was determined by measuring the resistance distribution and calculating the value at which the base portion and the highest resistance were obtained. Li deposition resistance was determined by running a predetermined program and measuring the capacity retention rate after 300 cycles. For AC-IR, measurements were started after the injection of the non-aqueous electrolyte, and the time it took for the resistance to become constant was measured.

[0066] We marked resistance uniformity as follows: "◎" for resistance less than 5mΩ, "○" for resistance greater than 5mΩ but less than 10mΩ, "△" for resistance greater than 10mΩ but less than 20mΩ, and "×" for resistance greater than 20mΩ.

[0067] We rated the volume retention rate, which indicates resistance to Li precipitation, as follows: "◎" for values ​​greater than 98%, "〇" for values ​​greater than 96% but less than 98%, "△" for values ​​greater than 94% but less than 96%, and "×" for values ​​less than 94%.

[0068] The uniformity of resistance was "◎" for Examples 1 and 2, "○" for Example 3, "△" for Comparative Example 1, and "×" for Comparative Example 2. Li precipitation resistance was "◎" for Examples 1 and 2, "○" for Example 3, and "△" for Comparative Examples 1 and 2.

[0069] The AC-IR treatment time was 2 hours for Example 1, 2.5 hours for Example 2, 3.5 hours for Example 3 and Comparative Example 1, and 2 hours for Comparative Example 2. As shown in Figure 9, Examples 1-3, in which the immersion process was carried out at the immersion temperature of the non-aqueous electrolyte determined based on the measured amount of sodium, yielded excellent results in terms of resistance uniformity and Li deposition resistance. Furthermore, for AC-IR, results within an acceptable range were obtained in all of Examples 1-3 and Comparative Examples 1 and 2. [Explanation of symbols]

[0070] 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...Electrode 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

Claims

1. A method for manufacturing a non-aqueous secondary battery having a positive electrode sheet, a negative electrode sheet, and a non-aqueous electrolyte containing a film-forming material containing a lithium salt, A measurement step of measuring the amount of sodium in the sodium salt contained in the electrode body before injecting the non-aqueous electrolyte, The process includes a penetration step in which the non-aqueous electrolyte is permeated into the positive electrode sheet and the negative electrode sheet at a penetration temperature determined based on the measured amount of sodium, The aforementioned coating material is LiBOB (lithium bisoxalate borate). A method for manufacturing a non-aqueous secondary battery.

2. Prior to the aforementioned infiltration step, the injection step includes injecting the non-aqueous electrolyte at an injection temperature determined based on the measured amount of sodium. A method for manufacturing a non-aqueous secondary battery according to claim 1.

3. The penetration temperature determined in the aforementioned penetration process is negatively correlated with the amount of sodium. A method for manufacturing a non-aqueous secondary battery according to claim 1.

4. The injection temperature determined in the injection step is negatively correlated with the amount of sodium. A method for manufacturing a non-aqueous secondary battery according to claim 2.

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