Method for manufacturing battery

Abstract

To provide a method for manufacturing a battery capable of shortening an amount of time of aging treatment in a first aging step and a second aging step.SOLUTION: A method for manufacturing a battery includes: a first injection step of injecting a first electrolytic solution that contains lithium bis(fluorosulfonyl)imide into an electrode body having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a first charging step of performing first charging after the first injection step; a first aging step of performing aging treatment after the first charging step; a second injection step of injecting a second electrolytic solution that does not contain lithium bis(fluorosulfonyl)imide into the electrode body after the first aging step; a second charging step of performing second charging after the second injection step; and a second aging step of performing aging treatment after the second charging step.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a battery. [Background technology]

[0002] In the case of conventional batteries, the use of two or more kinds of electrolytes in combination has been considered. When manufacturing such batteries, for example, a first electrolyte is injected into an electrode body, charging and aging are performed, and then a second electrolyte is injected and charging and aging are performed.

[0003] For example, Patent Document 1 discloses a method for manufacturing a nonaqueous electrolyte secondary battery, which includes the steps of preparing an assembly including a positive electrode, a negative electrode, and a first electrolyte solution that is substantially free of lithium bis(fluorosulfonyl)imide and contains a negative electrode film-forming agent, forming a film on the negative electrode in the assembly using the negative electrode film-forming agent, and injecting a second electrolyte solution containing lithium bis(fluorosulfonyl)imide into the assembly.

[0004] Patent Document 2 also discloses a secondary battery having a negative electrode sheet and an electrolyte, the negative electrode sheet comprising a negative electrode current collector and a negative electrode film disposed on at least one surface of the negative electrode current collector and containing a negative electrode active material, the electrolyte having an electrolyte salt and an organic solvent, the negative electrode active material containing a silicon-based material, the organic solvent containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC), the weight occupancy of the ethylene carbonate (EC) in the organic solvent being ≦10%, and the weight occupancy of the ethyl methyl carbonate (EMC) in the organic solvent being 70% to 95%.

[0005] Patent Document 3 also discloses a secondary battery including an electrolyte solution having an electrolyte salt and an organic solvent, the electrolyte salt including lithium bisfluorosulfonylimide (LiFSI) and lithium hexafluorophosphate (LiPF6), the volume molar concentration of lithium bisfluorosulfonylimide (LiFSI) in the electrolyte solution being 0.8 mol / L to 1.2 mol / L, the volume molar concentration of lithium hexafluorophosphate (LiPF6) in the electrolyte solution being 0.15 mol / L to 0.4 mol / L, the organic solvent including ethylene carbonate (EC), and the mass occupancy of ethylene carbonate (EC) in the organic solvent being ≦20%. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2022-141405 [Patent Document 2] Special Publication No. 2022-553168 [Patent Document 3] Special Publication No. 2022-551946 Summary of the Invention [Problem to be solved by the invention]

[0007] In the equipment for manufacturing batteries, for example, SUS304 is used as stainless steel, and SUS304 and SUS430 may be used together. This "SUS304" or "SUS304 and SUS430" may be mixed into the electrode body. If such foreign matter is mixed into the electrode body, it can be dissolved and precipitated by performing a long-term aging treatment. However, performing a long aging treatment is undesirable from the viewpoint of the complexity of the manufacturing process, etc., and therefore a method for manufacturing a battery that can dissolve and precipitate any foreign matter that has been mixed in and can shorten the aging treatment time is desired.

[0008] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a battery manufacturing method capable of shortening the aging treatment time in the first aging step and the second aging step. [Means for solving the problem]

[0009] Means for solving the above problems include the following aspects. <1> A first liquid injection step of injecting a first electrolytic solution containing lithium bis(fluorosulfonyl)imide into an electrode assembly having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a first charging step of performing a first charging step after the first liquid injection step; a first aging step of performing an aging treatment after the first charging step; a second liquid injection step of injecting a second electrolytic solution not containing lithium bis(fluorosulfonyl)imide into the electrode body after the first aging step; a second charging step of performing a second charging step after the second liquid injection step; a second aging step of performing an aging treatment after the second charging step; A method for manufacturing a battery having the above structure. <2> The second electrolyte solution contains lithium hexafluorophosphate. <1> A method for manufacturing the battery according to claim 1. <3> The operating potential of the positive electrode active material contained in the positive electrode is 4V (vs. Li / Li + ) or less, <1> or <2> A method for manufacturing the battery according to claim 1. Effect of the Invention

[0010] According to the present disclosure, there is provided a battery manufacturing method capable of shortening the aging treatment time in the first aging step and the second aging step. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 shows a scheme of a method for manufacturing a battery according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic cross-sectional side view for explaining an experimental device used in an experimental example. [Diagram 3] FIG. 3 is a schematic cross-sectional view from above of the experimental setup shown in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment that is an example of the present disclosure will be described. These descriptions and examples are merely illustrative of the embodiment, and are not intended to limit the scope of the invention. In the present specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range. In addition, in the present specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. In this specification, the term "step" refers not only to an independent step, but also to a step that cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved.

[0013] Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if the composition contains multiple substances corresponding to each component, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0014] <Battery manufacturing method> The method for producing a battery according to an embodiment of the present disclosure includes the following steps as shown in the scheme of FIG. (First liquid injection step) A step of injecting a first electrolyte solution containing lithium bis(fluorosulfonyl)imide (LiFSI) into an electrode assembly having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. (First charging step) A step of performing the first charging step after the first liquid injection step. (First aging step) A step of performing aging treatment after the first charging step. (Second electrolyte injection step) A step of injecting a second electrolyte solution not containing lithium bis(fluorosulfonyl)imide (LiFSI) into the electrode body after the first aging step. (Second charging step) A step of performing a second charge after the second liquid injection step. (Second aging step) A step of performing aging treatment after the second charging step.

[0015] The battery manufacturing method according to the embodiment of the present disclosure includes the above steps, and thus can shorten the aging treatment time in the first aging step and the second aging step. The reason for this is believed to be as follows.

[0016] In a typical liquid-based battery, for example, an electrode body having a positive electrode, a negative electrode, and a separator is prepared, and an electrolyte is injected into the electrode body, followed by initial charging and aging treatment to manufacture the battery. In addition, for the purpose of improving various battery performances, two or more types of electrolytes are injected, and for example, a battery is manufactured by injecting a first type of electrolyte into the electrode body, charging and aging treatment, and then injecting a second type of electrolyte, charging and aging treatment.

[0017] Incidentally, in equipment for manufacturing batteries, more specifically, in equipment for manufacturing an electrode assembly having a positive electrode, a negative electrode, and a separator before injection of an electrolyte, for example, SUS304 is used as the stainless steel, and SUS304 and SUS430 may also be used in combination. There is a risk that this "SUS304" or "SUS304 and SUS430" (hereinafter simply referred to as SUS foreign matter) may be mixed into the electrode assembly. If this SUS foreign matter is mixed into the electrode assembly, it can be dissolved and precipitated by performing a long-term aging treatment. However, performing a long-term aging treatment is undesirable from the viewpoints of the complexity of the manufacturing process and the cost. Therefore, a method for manufacturing a battery that can dissolve and precipitate SUS foreign matter even when there is a risk of SUS foreign matter being mixed into the electrode body and can shorten the aging treatment time is desired.

[0018] In contrast, in a battery manufacturing method according to an embodiment of the present disclosure, in which both a first electrolytic solution containing LiFSI and a second electrolytic solution not containing LiFSI are injected into an electrode body, the first electrolytic solution is first injected into the electrode body and a first charging step and a first aging step are performed, and then the second electrolytic solution is injected and a second charging step and a second aging step are performed. Here, if a first electrolytic solution containing LiFSI is injected in the first liquid injection step, and then a second electrolytic solution not containing LiFSI is injected in addition to the first electrolytic solution in the second liquid injection step, the SUS foreign matter will dissolve in the first electrolytic solution in the first aging step, and the SUS foreign matter will dissolve in the mixed electrolytic solution of the first and second electrolytic solutions in the second aging step. On the other hand, if a second electrolytic solution not containing LiFSI is injected in the first liquid injection step, and then a first electrolytic solution containing LiFSI is injected in addition to the second electrolytic solution in the second liquid injection step, the SUS foreign matter will dissolve in the second electrolytic solution in the first aging step, and the SUS foreign matter will dissolve in the mixed electrolytic solution of the first and second electrolytic solutions in the second aging step. As described below, the first electrolyte solution containing LiFSI has a higher solubility of SUS foreign matter than the second electrolyte solution not containing LiFSI. Therefore, in the battery manufacturing method according to the embodiment of the present disclosure, the electrolyte solutions injected in the first electrolyte injection step and the second electrolyte injection step are injected in the above order, thereby making it possible to shorten the time of the aging treatment.

[0019] (Experimental Example) Here, the solubility of SUS304 and SUS430 after aging treatment in a first electrolytic solution containing LiFSI, a second electrolytic solution not containing LiFSI, and a mixed electrolytic solution of the first and second electrolytic solutions will be described with reference to experimental examples.

[0020] First, the experimental apparatus used will be described. Fig. 2 is a schematic cross-sectional side view showing the configuration of an experimental apparatus using a cyclic voltammetry method, and Fig. 3 is a schematic cross-sectional top view of the experimental apparatus shown in Fig. 2. As shown in Fig. 2 and Fig. 3, the experimental device 10 includes a working electrode 42 (specifically, SUS304 foil or SUS430 foil), a terminal 420 that also serves as a screw cap that contacts the working electrode 42 from the back side, a counter electrode 44 (specifically, Li foil) arranged opposite the working electrode 42, a terminal 440 that also serves as a screw cap that contacts the counter electrode 44 from the back side, a reference electrode 46 (specifically, Li foil), and a terminal 460 that also serves as a screw cap that contacts the reference electrode 46 from the back side. The working electrode 42, the counter electrode 44, and the reference electrode 46 are connected through a space 20 for injecting the electrolyte 2 provided inside the device, and an openable and closable screw cap 6 is provided at the opening of the space 20. The diameter a of the area where the space 20 contacts the working electrode 42, the counter electrode 44, and the reference electrode 46 (i.e., the area where the electrolyte 2 injected into the space 20 contacts) is φ10 mm.

[0021] A SUS304 foil or a SUS430 foil was provided on the working electrode 42 of this experimental device 10, and Li foil was provided on the counter electrode 44 and the reference electrode 46. The working electrode 42, the counter electrode 44, and the reference electrode 46 were all sealed with terminals 420, 440, and 460, which also served as screw caps. Next, an electrolyte was injected from the inlet of the space 20 so that the areas in contact with the working electrode 42, the counter electrode 44, and the reference electrode 46 were all filled with the electrolyte, and then the inlet was sealed with the screw cap 6. The following three types of liquid were used as the electrolyte. First electrolyte containing LiFSI - Second electrolyte that does not contain LiFSI (specifically, electrolyte that contains LiPF6) · Mixture of the first and second electrolytes

[0022] And 2.80~3.83V (vs. Li / Li + The maximum current density was measured. The results are shown in Table 1. The results are shown as a percentage relative to the result of an example in which SUS304 foil was used for the working electrode 42 and a mixed electrolyte solution of the first electrolyte solution and the second electrolyte solution was used as the electrolyte (=100).

[0023] [Table 1]

[0024] As shown in Table 1, in the first aging process, a first electrolyte solution containing LiFSI is injected in the first liquid injection process, and then a second aging process is performed by injecting a second electrolyte solution not containing LiFSI in addition to the first electrolyte solution in the second liquid injection process. In this case, the ratio to the reference value in the first aging process is "1295," and in the second aging process it is "100." On the other hand, if a second electrolyte solution not containing LiFSI is injected in a first liquid injection process to perform a first aging process, and then a first electrolyte solution containing LiFSI is injected in addition to the second electrolyte solution in a second liquid injection process to perform a second aging process, the ratio to the reference value in the first aging process is "1.60" and in the second aging process it is "100". In other words, the former can be aged at a ratio of 1295 to the reference value in the first aging step and at a ratio of 100 to the reference value in the second aging step, whereas the latter can only be aged at a ratio of 1.60 to the reference value in the first aging step and then at a ratio of 100 to the reference value in the second aging step. From the above results, it can be seen that when SUS304 is mixed into the electrode body, injecting a first electrolyte solution containing LiFSI in the first electrolyte injection process and injecting a second electrolyte solution not containing LiFSI in the second electrolyte injection process can more efficiently dissolve and precipitate SUS304, thereby shortening the overall aging treatment time.

[0025] Even when SUS430 is mixed in the electrode body in addition to SUS304, the result for the first electrolyte is a ratio of "1457" to the reference value, and the result for the mixed electrolyte of the first electrolyte and the second electrolyte is a ratio of "14767" to the reference value, as shown in Table 1. Therefore, even when SUS430 is mixed in addition to SUS304, it can be seen that SUS430 can also be efficiently dissolved and precipitated by injecting the first electrolyte containing LiFSI in the first electrolyte injection step and injecting the second electrolyte not containing LiFSI in the second electrolyte injection step.

[0026] Next, the configuration of a battery manufactured by a battery manufacturing method according to an embodiment of the present disclosure will be described.

[0027] The battery comprises an electrode assembly having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a first electrolytic solution and a second electrolytic solution injected into the electrode assembly.

[0028] (electrolyte) The electrolytic solution is a solution in which a supporting salt serving as an electrolyte is dissolved or dispersed in a solvent. Examples of the solvent include propylene carbonate (PC), fluoroethylene carbonate (FEC), and ethyl carbonate (EC).

[0029] The indicator salt in the first electrolytic solution (electrolytic solution containing lithium bis(fluorosulfonyl)imide) is preferably lithium bis(fluorosulfonyl)imide (LiFSI). As the indicator salt in the second electrolyte (an electrolyte not containing lithium bis(fluorosulfonyl)imide), for example, lithium hexafluorophosphate (LiPF6) is preferable. The electrolytic solution may contain various additives (for example, lithium bis(oxalato)borate, etc.).

[0030] (Negative electrode) The negative electrode contains at least a negative electrode active material. The negative electrode may contain at least one of a conductive material and a binder.

[0031] Examples of the negative electrode active material include Li-based active materials such as metallic lithium and lithium alloys, carbon-based active materials such as graphite and hard carbon, oxide-based active materials such as lithium titanate, and Si-based active materials such as simple silicon, Si alloys, silicon oxide, etc. The conductive material and binder used in the negative electrode are the same as those used in the positive electrode layer described above. Examples of the negative electrode active material include metal active materials such as Li and Si, carbon active materials such as graphite, and Li4Ti5O 12The negative electrode current collector may be in the form of, for example, a foil or a mesh.

[0032] The conductive material and binder used in the negative electrode are the same as those used in the positive electrode layer. The thickness of the negative electrode is, for example, 0.1 μm or more and 1000 μm or less.

[0033] (positive electrode) The positive electrode has, for example, a positive electrode current collector (e.g., aluminum foil, etc.) and a positive electrode active material layer supported by the positive electrode current collector. The positive electrode active material layer is made of a known positive electrode active material (e.g., LiNiO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM), and may further contain a known conductive material (for example, carbon black, etc.) and a known binder (for example, polyvinylidene fluoride, etc.). The thickness of the positive electrode active material layer is not particularly limited, and is preferably 0.1 μm to 1 mm.

[0034] The operating potential of the positive electrode active material contained in the positive electrode is 4V (vs. Li / Li + ) or less. + When using the following positive electrode active material (e.g., LFP, etc.), the effect of dissolving and precipitating SUS foreign matter by injecting the electrolyte in the first liquid injection step and the second liquid injection step in the above-mentioned order can be more efficiently achieved.

[0035] (Separator) The separator electrically insulates the positive electrode from the negative electrode, and provides a path for lithium ions to move between the positive electrode active material layer and the negative electrode active material layer. Examples of the separator include a microporous resin sheet made of a resin such as polyethylene (PE). The separator may have a single layer structure or a multilayer structure. The thickness of the separator is not particularly limited, and is preferably 0.1 μm to 1000 μm.

[0036] (Application) Applications of the battery obtained by the battery manufacturing method according to the embodiment of the present disclosure include, for example, power sources for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). [Explanation of symbols]

[0037] 2 electrolyte, 6 screw cap, 10 experimental apparatus, 42 working electrode, 44 counter electrode, 46 reference electrode 420, 440, 460 terminals

Claims

1. A first liquid injection step of injecting a first electrolytic solution containing lithium bis(fluorosulfonyl)imide into an electrode assembly having a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a first charging step of performing a first charging step after the first liquid injection step; a first aging step of performing an aging treatment after the first charging step; a second liquid injection step of injecting a second electrolytic solution not containing lithium bis(fluorosulfonyl)imide into the electrode body after the first aging step; a second charging step of performing a second charging step after the second liquid injection step; a second aging step of performing an aging treatment after the second charging step; A method for manufacturing a battery having the above structure.

2. The method for producing a battery according to claim 1 , wherein the second electrolyte solution contains lithium hexafluorophosphate.

3. The operating potential of the positive electrode active material contained in the positive electrode is 4 V (vs. Li / Li ＋ 3. The method for producing a battery according to claim 1 or 2, wherein the total mass of the battery is 1000 mol / L or less.

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