JP6958475B2 - Electrode plate manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing an electrode plate in a battery using a non-aqueous electrolytic solution and an electrode laminate. More specifically, the present invention relates to a method for manufacturing an electrode plate having a size cut out from a large-sized electrode original plate and laminated in an electrode laminate.

Conventionally, an electrode laminate formed by laminating positive and negative electrode plates has been used as a component of a battery. The electrode plate laminated in the electrode laminate is generally manufactured as a large-sized electrode original plate, and is cut to a size suitable for lamination. As a cutting method for this purpose, the one disclosed in Patent Document 1 can be mentioned. In the method of the same document, a solvent containing a binder resin is applied to the planned cutting portion of the electrode original plate (referred to as "band-shaped current collector" in the document). Then, the applied portion is irradiated with ultraviolet rays. After that, cutting will be performed. By softening the planned cutting location in advance to make it easier to cut, the life of the cutting blade is extended.

JP-A-2015-173081

However, the above-mentioned conventional technique has the following problems. As the solvent is applied to a part of the electrode plate, the battery performance deteriorates. This is because the properties of the electrode plate inevitably change due to the application of the solvent. For the time being, this document attempts to minimize such performance degradation. Therefore, the binder resin in the solvent to be applied is the same as that used when forming the active material layer of the electrode plate. However, even so, it is undeniable that the amount of binder resin will be excessive compared to the original composition. In addition, components other than the binder resin in the applied solvent must be removed. Therefore, in the technique of the same document, it is obliged to insert a vacuum drying process after cutting.

The present invention has been made to solve the problems of the above-mentioned conventional techniques. That is, the problem is to provide a method for manufacturing an electrode plate, which can obtain an electrode plate by satisfactorily cutting the electrode original plate in a simple process without impairing the battery performance.

The method for manufacturing an electrode plate according to one aspect of the present invention is a method for manufacturing an electrode plate in a battery using a non-aqueous electrolyte solution and an electrode laminate, and comprises coating an electrode active material layer on a current collecting foil. The size is such that the liquid supply step of supplying the liquid to the electrode active material layer of the electrode original plate and the portion of the electrode original plate after the liquid supply step where the liquid is supplied to the electrode active material layer are cut and laminated in the electrode laminate. It has a cutting step of making an electrode plate. Here, the device that performs the liquid supply process is arranged upstream from the device that performs the cutting process in the flow direction of the electrode original plate, and the liquid supply in the liquid supply process is intermittently performed in the cutting process on the electrode original plate. This is done when the part to be cut in is passed through the liquid supply part. The liquid supplied in the liquid supply process has the same components as the solvent of the non-aqueous electrolytic solution.

In the method for manufacturing the electrode plate in the above aspect, the electrode active material layer at the planned cutting portion of the electrode original plate is first moistened and softened in the liquid supply step. In that state, a cutting step is performed to cut the electrode original plate. The part to be cut is the part where the electrode active material layer is softened in the liquid supply process. Therefore, the electrode active material layer is less likely to be crushed by the pressure at the time of cutting, so that the cutting is performed well. In this way, a good electrode plate is manufactured. After that, even when the electrode plate is formed into an electrode laminate and built in the battery, the properties of the non-aqueous electrolyte of the battery do not change much depending on the liquid supplied in the liquid supply process. This is because the liquid has a component common to the solvent of the non-aqueous electrolytic solution. Therefore, it does not matter if the liquid supplied in the liquid supply step remains without being removed even after the cutting step.

According to this configuration, there is provided a method for manufacturing an electrode plate, which can satisfactorily cut an electrode original plate in a simple process to obtain an electrode plate without impairing battery performance.

It is a side view which shows the structure of the apparatus which carries out the manufacturing method of the electrode plate which concerns on this embodiment. It is a top view of the electrode original plate before cutting and the electrode plate after cutting. It is sectional drawing which shows the structure of the electrode laminated body conceptually. It is a top view which shows the solvent supply area in an Example. It is a top view explaining the exposure width measured in an Example.

Hereinafter, embodiments embodying the present invention will be described in detail with reference to the accompanying drawings. This embodiment embodies the present invention as a method for manufacturing an electrode plate carried out by the apparatus shown in FIG. The device of FIG. 1 is a device for obtaining an electrode plate 3 by cutting an electrode original plate 1 with a cutter 2. In addition to the cutter 2, the device of FIG. 1 is provided with an entry-side roller 4, a spray nozzle 5, and an exit-side roller 6.

FIG. 2 shows a plan view of the electrode original plate 1 cut by the apparatus of FIG. 1 and the electrode plate 3 after cutting. The electrode original plate 1 has a long strip shape extending in the left-right direction in FIG. The electrode original plate 1 is generally provided in the form of being wound into a coil, and is drawn out from the electrode original plate 1 and supplied to the entry side roller 4. The electrode plate 3 is formed by cutting the electrode original plate 1 in a direction intersecting the longitudinal direction thereof to form a card. The card-shaped electrode plate 3 is used as an electrode laminate 7 (see FIG. 3) by alternately stacking positive and negative electrodes. The electrode laminate 7 is built in the battery together with the non-aqueous electrolytic solution. Although only one positive and negative electrode plate 3 is shown in FIG. 3, of course, a larger number of positive and negative electrode plates 3 are laminated in the actual electrode laminated body 7.

The positive electrode plate 3 in FIG. 3 is formed by coating both the front and back surfaces of the current collector foil 8 with the positive electrode active material layer 9. In the negative electrode plate 3, both the front and back surfaces of the current collector foil 10 are covered with the negative electrode active material layer 11, and both sides thereof are covered with the separator layer 12. Instead of making the negative electrode plate 3 integrated with the separator, the positive electrode plate 3 can be made with the separator integrated, and neither the positive electrode plate 3 nor the positive or negative electrode plate 3 is made with the separator integrated type, and a separate film separator is prepared. It may be sandwiched between the positive and negative electrode plates 3 to form a separator layer. In either case, the separator layer is a porous layer made of an insulating material such as resin.

The device of FIG. 1 will be further described. The cutter 2 is a cutting tool for cutting the electrode original plate 1. The spray nozzle 5 supplies a liquid to the electrode original plate 1. The spray nozzle 5 is configured to supply liquid to both the front and back surfaces of the electrode original plate 1. The spray nozzle 5 is arranged on the upstream side of the cutter 2 with respect to the flow direction of the electrode original plate 1. In this embodiment, as the liquid supplied from the spray nozzle 5 to the electrode original plate 1, a liquid having a component used as a solvent for the above-mentioned non-aqueous electrolytic solution (hereinafter, referred to as “electrolyte solution solvent”) is used.

The manufacturing method of the electrode plate 3 carried out by the apparatus of FIG. 1 will be described. In the device of FIG. 1, the electrode original plate 1 is conveyed toward the cutter 2 by the entry side roller 4. The electrode original plate 1 passes through the location of the spray nozzle 5 before reaching the cutter 2. When the portion of the electrode original plate 1 to be cut by the cutter 2 passes through the portion of the spray nozzle 5, the spray nozzle 5 supplies the electrolytic solution solvent to the electrode original plate 1. That is, in this embodiment, the supply of the electrolytic solution solvent by the spray nozzle 5 is performed intermittently rather than continuously. The timing at which the spray nozzle 5 supplies the electrolyte solvent is controlled by the transport speed of the electrode original plate 1 and the widthwise dimension W (see FIG. 2) of the electrode plate 3. The widthwise dimension W of the electrode plate 3 and the distance W between the locations of the electrode original plate 1 to which the electrolyte solvent is supplied are the same.

The portion of the electrode original plate 1 to which the electrolyte solvent is supplied eventually reaches the portion cut by the cutter 2. At that time, the electrode original plate 1 is cut by the cutter 2. As a result, the electrode plate 3 is cut out from the electrode original plate 1. The cut-out electrode plate 3 is carried out by the output side roller 6.

Here, in the electrode original plate 1, the portion where the cutting is performed by the cutter 2 is the portion where the electrolytic solution solvent is supplied by the spray nozzle 5 as described above. This has the following advantages. First, the peeling of the electrode active material layer (positive electrode active material layer 9, negative electrode active material layer 11) from the current collector foils 8 and 10 in the vicinity of the cut portion is compared with the case where the electrolyte solvent is not supplied. And a small amount. Secondly, it has excellent charge / discharge performance when assembled as a battery.

The first advantage is obtained because the electrode active material layer is moistened with the electrolyte solvent and becomes flexible at the time of cutting. Therefore, the electrode active material layer is not broken by the pressure from the cutter 2 at the time of cutting. Therefore, the degree of residual of the positive electrode active material layer 9 and the negative electrode active material layer 11 in the electrode plate 3 after cutting is high. This means that the effective battery reaction area of the electrode plate 3 is wide and the storage capacity of the battery is large.

The reason for obtaining the second advantage is the type of components of the electrolyte solvent. The fact that the electrolytic solution solvent has the same composition as the solvent of the non-aqueous electrolytic solution means that the properties of the non-aqueous electrolytic solution do not change much even if the electrolytic solution solvent is mixed in the non-aqueous electrolytic solution. This means that even if the electrolyte solvent remains at that location after cutting, the properties of the non-aqueous electrolyte do not change much when the electrode plate 3 is incorporated into the battery. Therefore, the charge / discharge performance of the battery is not impaired by the residual electrolyte solvent for cutting.

If a liquid different from the above is used as the liquid supplied from the spray nozzle 5, the properties of the non-aqueous electrolytic solution may change if the liquid remains. As another type of liquid, for example, the kneading solvent used when kneading the material of the electrode active material layer can be considered. Even if it is a different kind of liquid, it has the effect of preventing the electrode active material layer from breaking during cutting. However, if different liquids are mixed with the non-aqueous electrolyte solution, the non-aqueous electrolyte solution may be denatured and the charge / discharge performance of the battery may be impaired. This is not the case with this embodiment.

A test was conducted to confirm the effect of the present invention in the cases shown in the following examples. Each condition in this example is as follows.

Negative electrode configuration:
-Current collector foil 10: Copper foil (10 μm thickness)
-Negative electrode active material layer 11:
・ ・ Active material: Natural graphite particles (particle size is about 80 μm)
Binder: Carboxymethyl cellulose, Styrene butadiene rubber Separator layer 12: Porous polyethylene film (20 μm thick, acrylic binder coated on both sides)
-Electrode surface size of the electrode plate 3: 112 mm x 72 mm

Positive electrode configuration:
-Current collector foil 8: Aluminum foil (10 μm thickness)
-Positive electrode active material layer 9:
・ ・ Active material: Nickel-manganese-chromium ternary lithium oxide (particle size is about 70 μm) ・ ・ Binder: Polyvinylidene fluoride ・ Electrode surface size of electrode plate 3: 110 mm × 70 mm

In other words, this is a lithium-ion battery, and ethyl methyl carbonate (dimethyl carbonate is also acceptable) was used as the solvent for the non-aqueous electrolyte solution. Then, ethyl methyl carbonate was also used as the liquid supplied from the spray nozzle 5. As shown in FIG. 4, the supply region 13 has a width of 10 mm centered on the planned cutting line 14. Then, as shown in FIG. 5, the maximum width of the exposed portion 15 formed on the cut pieces (upper side and lower side in FIG. 5) of the electrode plate 3 after cutting was measured.

The results are shown in Table 1. The column of "Liquid supply amount" in Table 1 shows the supply amount of the electrolytic solution solvent by the spray nozzle 5 per the area of the supply area 13 in FIG. The column of "time difference" indicates the time lag from the supply of the electrolytic solution solvent by the spray nozzle 5 to the cutting by the cutter 2. This was adjusted by the distance between the spray nozzle 5 and the cutter 2 in FIG. The column of "exposure width" is the test result, and is the measured value of the maximum width of the exposed portion 15 shown in FIG. Table 1 shows the values for the negative electrode plate 3. Although the negative electrode plate 3 is a separator integrated type as described above, the action of wetting the negative electrode active material layer 11 is exhibited even if the electrolytic solution solvent is supplied from above the separator layer 12. This is because the separator layer 12 is porous.

In Examples 1 to 3 in Table 1, the liquid supply amount was changed while keeping the time difference constant. Looking at these, even in Example 1 in which the liquid supply amount is the smallest, the exposure width is reduced to about 60% as compared with the comparative example (without liquid supply). In Examples 2 and 3 in which the amount of liquid supplied was increased, the exposure width was reduced to one-fourth or less as compared with the comparative example. However, the difference between Example 2 and Example 3 is not significant.

In Examples 4 to 6 in Table 1, the liquid supply amount was kept at the same level as in Example 3, but the time difference was changed. Even in Example 4 in which the time difference was shorter than that in Example 3, the effect was almost the same as that in Example 1. In Examples 5 and 6 in which the time difference was longer than that in Example 3, the effect was almost the same as that in Example 3. In particular, in Example 5 in which the time difference was 1 second, the best results were obtained in Table 1. From this, in the negative electrode plate 3, even if the time lag from liquid supply to cutting is as short as about 0.05 seconds, there is some effect, but it is more effective if the time lag is 0.5 seconds or more. You can see that. It is considered that this is because it takes a certain amount of time for the electrolytic solution solvent supplied from the spray nozzle 5 to permeate into the negative electrode active material layer 11 through the separator layer 12. If the separator is not integrated, it is considered that there is little need to take this time lag.

In the above-mentioned positive and negative electrode configurations, the solvent at the time of kneading is water or N-methyl-2-pyrrolidone, but if these liquids are supplied from the spray nozzle 5, the electrode active material layer is formed as described above. Although it has a softening effect, it is not good because it denatures the non-aqueous electrolyte solution. Further, particularly in the case of N-methyl-2-pyrrolidone, it is not good in that the acrylic binder layer on the surface of the separator layer 12 is dissolved. In this example, ethyl methyl carbonate, which is a component of the non-aqueous electrolyte solution, is used to prevent these harmful effects.

As described in detail above, according to the present embodiment and the embodiment, when cutting out the card-shaped electrode plate 3 from the long electrode original plate 1, the electrolytic solution solvent is first supplied to the planned cutting portion, and the supply thereof is performed. It is decided to cut the part that has been removed. As a result, a method for manufacturing an electrode plate has been realized, which enables good cutting without impairing battery performance, and does not require a particularly strict drying process after cutting.

It should be noted that the present embodiment is merely an example and does not limit the present invention in any way. Therefore, as a matter of course, the present invention can be improved and modified in various ways without departing from the gist of the present invention. For example, in the above-described embodiment and the embodiment, a mode in which the card-shaped electrode plate 3 is obtained by cutting the electrode original plate 1 in the direction perpendicular to the longitudinal direction thereof has been described. The electrode laminate 7 made of the electrode plate 3 was a flat stack type. However, the present invention is not limited to this, and the present invention is also applicable to a mode in which a long electrode original plate having a width of two rows is cut in two in parallel with the longitudinal direction thereof to obtain two long electrode plates. Applicable. In this case, the electrolyte solvent is supplied locally and continuously from the spray nozzle. In this case, the obtained electrode plate after cutting is usually a wound electrode laminate.

The target battery type is not limited to the lithium ion battery, but may be another type such as a nickel hydrogen battery. Further, the liquid having a component common to the solvent of the non-aqueous electrolytic solution does not need to completely match the solvent of the non-aqueous electrolytic solution. For example, when a mixed solution of two or more kinds of organic solvents is used as the solvent of the non-aqueous electrolytic solution, the electrolytic solution solvent supplied from the spray nozzle may have a different compounding ratio, or two or more kinds. It may lack some kinds of organic solvents of.

1 Electrode original plate 2 Cutter 3 Electrode plate 5 Spray nozzle 7 Electrode laminate 8 Current collecting foil 9 Positive active material layer 10 Current collecting foil 11 Negative negative active material layer 14 Scheduled cutting line

Claims (1)

A method for manufacturing an electrode plate in a battery using a non-aqueous electrolyte solution and an electrode laminate.
A liquid supply step of supplying a liquid to the electrode active material layer of the electrode original plate formed by coating the electrode active material layer on the current collector foil, and
It has a cutting step of cutting a portion of the electrode original plate after the liquid supply step in which the liquid is supplied to the electrode active material layer to obtain an electrode plate having a size to be laminated in the electrode laminate.
The device for performing the liquid supply step is arranged upstream of the device for performing the cutting step with respect to the flow direction of the electrode original plate.
The liquid is supplied intermittently in the liquid supply step when the portion of the electrode original plate to be cut in the cutting step passes through the liquid supply portion.
A method for producing an electrode plate, wherein the liquid supplied in the liquid supply step has a component common to the solvent of the non-aqueous electrolytic solution.

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