JP2007122889A - Manufacturing method of electrode, and electrode dryer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a group of electrodes of a uniform amount of contained water after drying. <P>SOLUTION: The manufacturing method of the electrodes is provided with processes (S2 to S10) of manufacturing a positive electrode sheet by adhering a positive electrode active material to a sheet-formed positive electrode material, processes (S12 to S20) of manufacturing a negative electrode sheet by adhering a negative electrode active material to a sheet-formed negative electrode material, a process (S30) of manufacturing a wound-around body by winding around a positive electrode sheet and a negative electrode sheet via a separator, and a process (S32) of drying the wound-around body. In this method, a weight reduction rate of the wound-around body during the drying process is derived and the drying process is ended based on the derived weight reduction rate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrode manufacturing method. The present invention also relates to an apparatus for drying an electrode. The “electrode” as used herein includes any of a positive electrode, a negative electrode, and a pair of a positive electrode and a negative electrode.

Various types of electrolytes and electrolytes are used for batteries. For example, a battery using a non-aqueous electrolyte that does not use water as a solvent is widely known. For example, a lithium ion battery uses an organic electrolytic solution or a solid electrolyte in which a lithium salt is dissolved in an organic solvent. In the case of a lithium ion battery, a positive electrode active material containing moisture is applied to the front and back surfaces of a metal sheet to produce a positive electrode sheet. Similarly, a negative electrode active material containing moisture is applied to the front and back surfaces of a metal sheet to produce a negative electrode. Next, a wound body is manufactured by winding the positive electrode sheet and the negative electrode sheet through a separator. The wound body is accommodated in a case, and the organic electrolyte is sealed in the case. Thereby, a lithium ion battery is completed.
In the case of a lithium ion battery, moisture is contained in the positive electrode active material and the negative electrode active material applied to the metal sheet. In the case of a lithium ion battery, if a large amount of moisture is contained in the positive electrode active material or the negative electrode active material, the water reacts with the electrolytic solution, decomposes the lithium salt in the electrolytic solution, and as a result, the performance of the battery is reduced. It is known to decline. For this purpose, for example, in the technique of Patent Document 1, the wound body is dried for a predetermined time before the electrolytic solution is sealed in the case.
JP 2000-12070 A

As in the above-described lithium ion battery, when the amount of moisture contained in the positive electrode active material or the negative electrode active material changes, the performance of the battery may change. Further, when the electrode material (metal sheet in the above example) itself absorbs moisture, the performance of the battery may change if the amount of moisture changes. The amount of moisture contained in the active material and electrode material before drying is different each time. For this reason, when the electrode material to which the active material is attached (hereinafter referred to as “electrode” for convenience) is dried for a predetermined time, the amount of moisture contained in the dried electrode is reduced. Variations appear. In this case, the battery performance varies.
The present invention was created in view of the above-described circumstances, and provides a technique capable of mass-producing an electrode group in which the amount of moisture contained after drying is uniform.

If the amount of moisture contained in the electrode before drying is known, the amount of moisture contained in the electrode after drying can be adjusted to a desired amount by adjusting the drying time. However, it is very difficult to know the amount of moisture in the electrode before drying.
The present inventors paid attention to the fact that when the amount of moisture contained in the electrode changes, the amount of evaporation of the moisture per unit time changes. When the electrode contains a large amount of moisture, the amount of evaporation per unit time increases, and when the electrode does not contain much moisture, the amount of evaporation per unit time decreases. The amount of evaporation of water contained in the electrode per unit time is equal to the amount of weight loss per unit time of the electrode. In the present specification, the “weight reduction amount per unit time” is referred to as a weight reduction rate. When the weight reduction rate of the electrode is large, the amount of moisture contained in the electrode is large, and when the weight reduction rate of the electrode is small, the amount of moisture contained in the electrode is small. For this reason, when the drying of the electrode is terminated when the weight reduction rate corresponding to a predetermined amount of water is reached, an electrode containing the predetermined amount of water can be manufactured. The present invention has been created based on such knowledge.

The electrode manufacturing method of the present invention includes a step of attaching an active material to an electrode material, a step of drying an electrode material to which the active material is attached (referred to as an electrode for convenience), and a weight reduction rate of the electrode during the drying step. A deriving step, and a step of ending the drying step based on the derived weight reduction rate.
The above-described electrode is a concept including all of a positive electrode, a negative electrode, and a pair of a positive electrode and a negative electrode. Therefore, the drying step is not limited to drying the electrode material for the positive electrode or the negative electrode alone. It also includes drying the wound body around which the positive electrode sheet, the separator, and the negative electrode sheet are wound. In the drying step, a single continuous electrode material with an active material attached may be divided into a plurality of pieces and dried.
According to this electrode manufacturing method, the amount of moisture contained in the dried electrode can be adjusted. For example, when it is desired to set the amount of moisture contained in the dried electrode to a predetermined amount, the electrode may be dried until the weight reduction rate when the predetermined amount of moisture is contained. According to the present invention, even when the amount of moisture contained in the electrode before drying is different, the amount of moisture contained in the electrode after drying can be made uniform. An electrode group containing a uniform amount of moisture can be manufactured.
This method can be suitably used as a method of manufacturing an electrode for a battery whose performance changes when moisture is contained in the electrode. For example, it can be used when manufacturing an electrode used for a battery using a non-aqueous electrolyte.

In the above end step, the change in the weight reduction rate may be monitored during the drying step, and the drying step may be ended when the weight reduction rate becomes equal to or less than the first predetermined value.
Moreover, you may make it a said completion | finish process complete | finish a drying process, when the predetermined time passed since the weight decreasing rate became below 2nd predetermined value.

The following method is also one of the creations of the present invention. The electrode manufacturing method includes a step of manufacturing a positive electrode sheet by attaching a positive electrode active material to a sheet-like positive electrode material, a step of manufacturing a negative electrode sheet by attaching a negative electrode active material to a sheet-like negative electrode material, and a separator. A step of producing a wound body by winding the positive electrode sheet and the negative electrode sheet, a step of drying the wound body, a step of deriving a weight reduction rate of the wound body during the drying step, and a derived weight A step of ending the drying step based on the reduction rate is provided.
According to this method, the amount of moisture contained in the wound body after drying can be adjusted. An electrode group containing a uniform amount of moisture can be manufactured.

  In the above electrode manufacturing method, for example, a step of drying the positive electrode sheet after the positive electrode sheet manufacturing step and before the wound body manufacturing step, and a step of manufacturing the wound body after the negative electrode sheet manufacturing step A step of drying the negative electrode sheet may be further added before the step.

The positive electrode sheet can be dried before producing the wound body. This drying process can be completed based on the weight reduction rate of the positive electrode sheet. Similarly, the negative electrode sheet can be dried before producing the wound body. This drying process can be completed based on the weight reduction rate of the negative electrode sheet. When this method is adopted, it seems that it is not necessary to dry the wound body. However, when manufacturing a wound body, a positive electrode active material, a negative electrode active material, etc. may absorb the water | moisture content in air. For this reason, after the winding body is manufactured, the winding body must be dried again. In order to omit this wound body drying step, the following technique is provided.
That is, when the drying process of the positive electrode sheet is finished based on the weight reduction rate and the drying process of the negative electrode sheet is finished based on the weight reduction rate, the step of manufacturing the wound body is performed under a dry atmosphere. Is preferred.
If it does in this way, the process of drying a wound body after manufacturing a wound body can be omitted.

In addition, when the process of drying a wound body is abbreviate | omitted, it is preferable to employ | adopt the following technique. That is, when the positive electrode sheet and the negative electrode sheet are pressed before manufacturing the wound body, it is preferable that the pressing process is also performed in a dry atmosphere.
In this case, it is possible to prevent the positive electrode sheet and the negative electrode sheet from absorbing moisture during the pressing process.

  Each of the electrode manufacturing methods described above is suitable for a method for manufacturing an electrode used for a battery (for example, a lithium ion secondary battery) using a non-aqueous electrolyte solution. However, it can be used as a method for producing an electrode such as an all-solid battery or a dye-sensitized solar cell.

The following electrode drying apparatus is also one of the creations of the present invention. That is, the electrode drying apparatus according to the present invention was calculated with a drying furnace, an apparatus for measuring the weight of the electrode in the drying furnace, and an apparatus for calculating a weight reduction rate of the electrode during drying from the measured weight. A device for stopping the drying furnace based on the weight reduction rate is provided.
According to this apparatus, the amount of moisture contained in the electrode after drying can be adjusted. An electrode group containing a uniform amount of moisture can be manufactured.

First, the main features of the techniques described in the following examples are summarized.
(Form 1) An active material is apply | coated to both the front and back of a sheet-like electrode material.
(Mode 2) When an active material is applied to the surface of the electrode material, a drying step is performed. Thereafter, an active material is applied to the back surface of the electrode material. Thereafter, the drying process is performed again. These drying steps are performed by drying for a predetermined time. After the wound body is manufactured, the drying process is performed again. This drying process ends based on the weight loss rate.
(Form 3) A paste-like active material containing moisture is used.
(Mode 4) One long positive electrode sheet and one long negative electrode sheet are wound through a separator. When it is wound several times, the positive electrode sheet and the negative electrode sheet are cut to produce one wound body. By repeating this, a plurality of wound bodies are manufactured from one positive electrode sheet and one negative electrode sheet. A plurality of manufactured wound bodies are simultaneously dried.

First Embodiment An embodiment of the present invention will be described with reference to the drawings. In this embodiment, a lithium ion secondary battery is manufactured. FIG. 1 is a flowchart of the battery manufacturing method of this embodiment.
First, the process (step S2-S10) which manufactures a positive electrode sheet is demonstrated. In this embodiment, an aluminum sheet is used to manufacture the positive electrode sheet. A very long aluminum sheet having a length of about 5 (m) is used. A positive electrode active material is applied to the surface of the aluminum sheet (step S2). In this embodiment, a positive electrode active material using lithium nickelate as a raw material is used. A mixture of the positive electrode active material and the binder is dissolved in water to form a paste. In step S2, this paste-like positive electrode active material is applied to an aluminum sheet.
When the positive electrode active material is applied to the surface of the aluminum sheet, the aluminum sheet is dried (step S4). The drying process in step S4 is performed for a predetermined time (for example, 5 minutes) determined in advance. Moisture contained in the positive electrode active material applied to the aluminum sheet is skipped to some extent. Thereby, the positive electrode active material on the surface of the aluminum sheet becomes almost solid.
Subsequently, a positive electrode active material is applied to the back surface of the aluminum sheet (step S6). The positive electrode active material used here is the paste-like positive electrode active material used in step S2. If a positive electrode active material is apply | coated to the back surface of an aluminum sheet, an aluminum sheet will be dried (step S8). The drying process in step S8 is performed for a predetermined time (for example, 5 minutes) determined in advance. Thereby, the positive electrode active material on the back surface of the aluminum sheet is in a substantially solid state.
When the drying process in step S8 is completed, the aluminum sheet is pressed (step S10). As a result, the positive electrode active materials on the front and back surfaces of the aluminum sheet become dense. The positive electrode sheet is completed through steps S2 to S10.

Then, the process (step S12-S20) which manufactures a negative electrode sheet is demonstrated. The method for producing the negative electrode sheet is basically the same as the method for producing the positive electrode sheet. A copper foil sheet having a length of about 5 (m) is used. A negative electrode active material is applied to the surface of the copper foil sheet (step S12). A negative electrode active material made of carbon is used as a paste. In step S12, a paste-like negative electrode active material is applied to the copper foil sheet.
When the negative electrode active material is applied to the surface of the copper foil sheet, the copper foil sheet is dried (step S14). The drying process in step S14 is performed for a predetermined time (for example, 5 minutes) determined in advance. The negative electrode active material on the surface of the copper foil sheet becomes almost solid.
Then, a negative electrode active material is apply | coated to the back surface of a copper foil sheet (step S16). The negative electrode active material used here is the paste-like negative electrode active material used in step S12. If a negative electrode active material is apply | coated to the back surface of a copper foil sheet, a copper foil sheet will be dried (step S18). The drying process in step S18 is performed for a predetermined time (for example, 5 minutes) determined in advance. The negative electrode active material on the back surface of the copper foil sheet becomes almost solid.
When the drying process of step S18 is completed, the copper foil sheet is pressed (step S20). The negative electrode active materials on the front and back surfaces of the copper foil sheet become dense. The negative electrode sheet is completed through steps S12 to S20.

  The positive electrode sheet and the negative electrode sheet are wound through a separator (step S30). Thereby, the wound body accommodated in a battery case is manufactured. In this embodiment, a very long positive electrode sheet and negative electrode sheet are used. For this purpose, a plurality of wound bodies are manufactured from one positive electrode sheet and one negative electrode sheet. When the positive electrode sheet and the negative electrode sheet are wound several times, the positive electrode sheet is cut and the negative electrode sheet is cut. This completes one wound body. Subsequently, a second wound body is manufactured. The wound body is manufactured until the positive electrode sheet and the negative electrode sheet disappear.

When the wound body is manufactured, the process proceeds to step S32. In step S32, the wound body manufactured in step S30 is dried. In the above steps S4, S8, S14, and S18, the positive electrode sheet and the negative electrode sheet are dried, but may not be sufficiently dried. In addition, the active material may absorb moisture in the air during the pressing process in steps S10 and S20 and the wound body manufacturing process in step S30. For this purpose, the drying process of step S32 is performed. This drying step is performed after the wound body is accommodated in the battery case. The wound body is dried while being accommodated in the battery case.
The drying device used in step S32 will be described. FIG. 2 shows a schematic diagram of the drying apparatus 10. The drying apparatus 10 includes a drying furnace 20, heaters 22 and 24, a vacuum pump 26, an electronic balance 30, a table 32, a controller 70, and the like. The heaters 22 and 24 are attached to the side walls in the drying furnace 20. The heaters 22 and 24 are connected to the controller 70. The vacuum pump 26 is installed inside the drying furnace 20. The vacuum pump 26 is connected to the controller 70. The electronic balance 30 is in contact with the lower surface of the table 32 and measures the weight including the table 32. The electronic balance 30 is connected to the controller 70. The table 32 is placed on the electronic balance 30. The base 32 can hold a plurality of battery cases 50 containing the wound body.
The controller 70 comprehensively controls the operation of the drying apparatus 10. The controller 70 includes a CPU 72, a ROM 74, a RAM 76, a timer 80, and the like. The CPU 72 controls the heaters 22 and 24 and the vacuum pump 26 according to a control program stored in the ROM 74. Various programs are stored in the ROM 74. For example, a program for calculating the weight reduction rate from the weight measured by the electronic balance 30 is stored. Further, for example, a program for stopping the heaters 22 and 24 and the vacuum pump 26 based on the weight reduction rate is stored. The RAM 76 temporarily stores various types of information in the course of executing various types of processing. For example, the weight measured by the electronic balance 30 is stored. When the timer 80 receives the start signal output from the CPU 72, the timer 80 starts measuring time. This timer 80 is mainly used in a second embodiment to be described later.

In step S32 (see FIG. 1), first, each of the plurality of wound bodies manufactured in step S30 is placed in the battery case 50. Next, the battery case group 50 is placed on the base 32 of the drying apparatus 10. These operations are performed by workers. Subsequently, the worker activates the drying device 10. Thereby, the controller 70 starts the heaters 22 and 24 and the vacuum pump 26. The processing executed after that by the controller 70 will be described next.
FIG. 3 is a flowchart showing a part of processing executed by the controller 70. When the controller 70 starts the heaters 22 and 24 and the vacuum pump 26, the controller 70 executes the process of step S50. In step S50, the weight is measured. This process is executed by inputting the measurement value of the electronic balance 30. In the process of step S50, the weight including the battery case group 50 in which the wound body is accommodated and the base 32 is measured. The measured weight is stored in the RAM 74.
When measuring the weight, the controller 70 calculates a weight reduction rate (step S52). If the weight has been measured only once, the process of step S52 is skipped. In step S52, the difference between the weight measured in the previous step S50 and the weight measured in the current step S50 is calculated. It will be calculated how much the weight has been reduced. The amount of weight loss per unit time can be obtained. In this embodiment, the amount of weight reduction per unit time is referred to as “weight reduction rate”.
When the weight reduction rate is calculated, it is determined whether or not the weight reduction rate is equal to or less than a predetermined value A1 (step S54). If the weight reduction rate is greater than the predetermined value A1 (NO in step S54), the process returns to step S50. In step S50, the weight is measured again. In this embodiment, when returning from step S54 to step S50, step S50 is executed again after one hour has elapsed since the execution of the previous step S50. If step S50 is performed, the process of step S52 and step S54 will be performed. Therefore, in the process of step S52 of the present embodiment, the amount of weight reduction per hour is calculated.
If it is determined in step S54 that the weight reduction rate is equal to or less than the predetermined value A1 (in the case of YES), the process proceeds to step S56 and drying is terminated. This process is executed by the controller 70 stopping the heaters 22 and 24 and the vacuum pump 26. When the process of step S56 is finished, the drying process of step S32 of FIG. 1 is finished.

  When the drying process of step S32 in FIG. 1 is completed, an electrolytic solution is injected into the battery case group 50. In this embodiment, an organic electrolytic solution in which a lithium salt is dissolved in an organic solvent is used. It is preferable to perform the process of step S34 immediately after the process of step S32. This is to prevent the dried wound body from absorbing moisture in the air. Moreover, when not performing the process of step S34 immediately after finishing the process of step S32, it is preferable to keep the dried wound body in a dry atmosphere. A battery is completed by injecting an electrolyte into the battery case group 50.

FIG. 4 shows the relationship between the time when the positive electrode sheet is dried and the weight parts per million contained in the positive electrode sheet. The horizontal axis of FIG. 4 is time (Hour), and the vertical axis is the weight parts per million (ppm) of moisture contained in the positive electrode sheet. The weight parts per million in this experiment were measured chemically using chemicals. In this example, measurement was performed using the Karl Fischer measurement method. As shown in FIG. 4, it reached 3000 (ppm) in about 15 hours from the start of drying. Also, the weight parts per million decreased to 1000 (ppm) in about 45 hours after the start of drying. As the drying time becomes longer, the reduction rate of the contained water (that is, the slope of the tangent line in the graph of FIG. 4) becomes smaller.
FIG. 5 shows the relationship between the weight parts per million of moisture contained in the positive electrode sheet and the internal resistance of the battery. In this experiment, positive electrode sheets having various parts per million by weight were prepared. Each of these positive electrode sheets was combined with the same negative electrode sheet to produce a battery. The internal resistance was measured for each battery, and the results were plotted. The internal resistance (sometimes referred to as reaction resistance) is measured as follows. The battery is discharged for a predetermined time, and the potential difference and current at that time are measured. The value calculated by dividing the measured potential difference by the current is the internal resistance. When the internal resistance is small, a high output can be obtained and it can be said that the battery has excellent performance. As shown in FIG. 5, even when the weight percentage of moisture contained in the positive electrode sheet is 1000 (ppm) or less, the internal resistance is hardly changed. If the percentage by weight of water contained in the positive electrode sheet is 1000 (ppm), it can be said that the battery is extremely excellent.

“A1” in step S54 in FIG. 3 can be determined by employing various methods. For example, the slope of the tangent line at a certain point in the graph of FIG. 4 is the rate of weight reduction of the positive electrode sheet when the weight percentage at that point is. When the slope of the tangent line at the point A (the weight percentage contained in the positive electrode sheet is 1000 (ppm)) in the graph of FIG. 4 is determined, the decrease in the weight of the positive electrode sheet when the weight percentage is 1000 (ppm). A rate will be required. The above A1 can be determined based on the weight reduction rate.
For example, when the relationship of the weight reduction rate of the positive electrode sheet (the relationship as shown in FIG. 4) is substantially equal to the relationship of the weight reduction rate of the negative electrode sheet, the above A1 is determined only from the relationship of the weight reduction rate of the positive electrode sheet. be able to. In this case, the relationship between the weight reduction rates of the negative electrode sheet may be obtained and A1 may be determined from the relationship.
If the relationship between the weight reduction rate of the positive electrode sheet is not equal to the relationship between the weight reduction rate of the negative electrode sheet, the relationship between the weight reduction rate of the positive electrode sheet and the relationship between the weight reduction rate of the negative electrode sheet is obtained, and those relationships are obtained. From this, A1 may be determined. In this case, A1 may be determined from the relationship between the time when the positive electrode sheet and the negative electrode sheet are dried together and the weight parts per million contained in both electrode sheets. .

  According to the present embodiment, the drying of the wound body is finished based on the weight reduction rate. The weight loss rate at a certain point and the amount of water contained in the wound body at that point correlate very well. For this reason, even if there is a difference in the amount of water contained in the wound body before drying, if the drying is completed based on the weight reduction rate, the amount of water contained in the wound body after drying is set to a constant value. be able to. An experimental result showing this is shown in FIG. The horizontal axis of the graph of FIG. 6 is the weight percentage of moisture contained in the wound body before drying. A vertical axis | shaft is the weight percentage of the water | moisture content contained in the wound body after drying. A diamond point (a point not included in the range of the ellipse) is a plot of a result obtained by drying a plurality of wound bodies manufactured from different positive electrode sheets and negative electrode sheets for a certain period of time. A square point (a point included in the range of the ellipse) is a plot of the result when drying of the wound body is completed based on the weight reduction rate as in this example. As can be seen from FIG. 6, when the wound body is dried for a certain period of time, the amount of water contained in the wound body after drying varies. On the other hand, when the method of the present embodiment is adopted, the moisture content after drying is concentrated around a certain value (1000 (ppm)).

The amount of water contained in the positive electrode active material and the negative electrode active material changes every time the positive electrode sheet or the negative electrode sheet is manufactured. Moreover, since the humidity of the place where the step of pressing the positive electrode sheet or the negative electrode sheet (steps S10 and S20 in FIG. 1) or the step of winding (step S30) is constantly changed, the positive electrode sheet or The amount of moisture absorbed by the negative electrode sheet changes every time. Accordingly, the amount of moisture contained in the wound body before drying changes every time.
In order to realize a high-performance lithium ion secondary battery, it is necessary to reduce the amount of water contained in the wound body as much as possible. In order to dry a wound body containing a small amount of water, drying for a short time is sufficient, whereas in order to dry a wound body containing a large amount of water, a long time drying is required. When drying the wound body for a certain period of time as in the past, if the drying time necessary to dry the wound body containing a large amount of moisture is adopted, the wound body containing a small amount of moisture About drying time is wasted. However, if the drying time is set short so that there is no wasted drying time, the wound body containing a large amount of water cannot be sufficiently dried, and the performance of the battery is lowered.
According to this example, in order to adjust the drying time using the weight reduction rate, the wound body containing a large amount of moisture is dried for a long time, but the wound body containing only a small amount of moisture is used for a short time. Finish with drying. According to this example, a lithium ion secondary battery can be efficiently manufactured.

(Second Embodiment) A second embodiment of the present invention will be described. Here, the description will focus on the differences from the first embodiment. In this embodiment, the method for ending the drying process is different from that in the first embodiment. FIG. 7 shows a flowchart of processing executed by the controller 70 (see FIG. 2) in the drying process of this embodiment.
When the controller 70 starts the heaters 22 and 24 and the vacuum pump 26 (see FIG. 2), the controller 70 executes the processes of steps S60 and S62. These steps S60 and S62 are the same processes as steps S50 and S52 of FIG. When the weight reduction rate is calculated, it is determined whether the weight reduction rate is A2 or less (step S64). If NO in step S64, the process returns to step S60. If YES in step S64, the process proceeds to step S66 to start the timer 80 (see FIG. 2). When the timer 80 is started, it is monitored whether or not the count value of the timer 80 has reached T (step S68). When the value of timer 80 reaches T (YES in step S68), drying is terminated (step S70). That is, the heaters 22 and 24 and the vacuum pump 26 are stopped.

The time from reaching point B shown in FIG. 4 to reaching point A was about 30 hours. That is, the time from when the weight parts per million reached 3000 (ppm) until it reached 1000 (ppm) was about 30 hours. It is possible to obtain the time required from when the moisture contained in the wound body reaches a predetermined amount until it reaches a desired amount.
In the present embodiment, the drying is finished when the time T has elapsed after the weight reduction rate becomes A2. Even in this case, the amount of moisture contained in the wound body after drying can be made uniform. According to this example, the end of drying is determined when the change in the weight reduction rate is large. In this way, even when an electrode with a very small change in weight reduction rate is manufactured, the end of drying can be determined accurately.

(Third Embodiment) A third embodiment of the present invention will be described. Here, the description will focus on the differences from the first embodiment. FIG. 8 shows a flowchart of the battery manufacturing method of this embodiment.
Steps S102 to S106 are the same as steps S2 to S6 in FIG. In the drying process of step S108, the drying apparatus 10 shown in FIG. 2 is used, and the end of drying is determined based on the weight reduction rate. That is, the drying process of step S108 is performed according to the flowchart of FIG. When the drying process in step S108 is completed, the process proceeds to the pressing process in step S110. This step is performed under a dry atmosphere. That is, the pressing process is performed in a space where the humidity is very low. The positive electrode sheet is completed under a dry atmosphere. The completed positive electrode sheet is managed under a dry atmosphere.
Steps S112 to S116 are the same as steps S12 to S16 in FIG. In the drying process of step S118, the drying apparatus 10 shown in FIG. 2 is used, and the end of drying is determined based on the weight reduction rate. The drying process of step S118 is performed according to the flowchart of FIG. When the drying process in step S118 is completed, the process proceeds to the pressing process in step S120. This step is performed under a dry atmosphere. The completed negative electrode sheet is managed under a dry atmosphere.

In step S130, the positive electrode sheet and the negative electrode sheet are wound through the separator. Thereby, a wound body is manufactured. Step S130 is also performed under a dry atmosphere. In this embodiment, the drying process (step S32 in FIG. 1) is not performed after the wound body is manufactured. When step S130 is completed, the electrolytic solution is injected after the wound body is placed in the battery case (step S132). The process of step S132 is also performed under a dry atmosphere.
In the present embodiment, after performing the drying process of step S108 and step S118, the work is performed under a dry atmosphere. For this reason, the process of drying a wound body can be skipped. According to the present embodiment, the electrode can be manufactured efficiently.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
(1) In the above-described examples, the weight reduction amount per hour was adopted as the weight reduction rate. However, the length of time can be changed as appropriate. For example, the weight reduction rate may be calculated by creating a graph showing the relationship between the measured weight and time during drying and obtaining the slope of the tangent line of the graph.
(2) In the above-described embodiment, the method for manufacturing the lithium ion secondary battery has been described. However, this method can be applied to other battery manufacturing methods. For example, it can be applied to a method for producing an all-solid battery, a dye-sensitized solar cell, or the like.
(3) Numerical values such as A1, A2, and T in each of the above-described embodiments can be changed as appropriate. For example, the weight of the battery case 50 group that houses the wound body is measured before the drying process is started, and a numerical value such as A1 can be determined based on the weight.
(4) Further, in the drying process of any one of steps S4, S8, S14, and S18 of the first embodiment, the end of drying may be determined based on the weight reduction rate.
(5) You may make it dry a wound body in the state which is not accommodated in a battery case.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The flowchart of the battery manufacturing method of 1st Example is shown. The schematic of a drying apparatus is shown. The flowchart of the process which a controller performs in a drying process is shown. The relationship between the drying time and the weight parts per million of water contained in the positive electrode sheet is shown. The relationship between the weight parts per million of moisture contained in the positive electrode sheet and the internal resistance is shown. The relationship between the weight parts per million of water contained in the wound body before drying and the weight parts per million of water contained in the wound body after drying is shown. The flowchart of the process which a controller performs in a drying process is shown (2nd Example). The flowchart of the battery manufacturing method of 3rd Example is shown.

Explanation of symbols

10: drying device 20: drying furnace 22: heater 24: heater 26: vacuum pump 30: electronic balance 32: stand 50: battery case 70: controller 72: CPU
74: ROM
76: RAM
80: Timer

Claims (9)

An electrode manufacturing method,
A step of attaching an active material to the electrode material, a step of drying the electrode material to which the active material is attached, and a step of deriving a weight reduction rate of the “electrode material to which the active material is attached” during the drying step. An electrode manufacturing method provided with the process of complete | finishing a drying process based on a weight decreasing rate.   2. The electrode manufacturing method according to claim 1, wherein the finishing step ends the drying step when the derived weight reduction rate becomes equal to or less than a first predetermined value.   2. The electrode manufacturing method according to claim 1, wherein the ending step ends the drying step when a predetermined time elapses after the derived weight reduction rate becomes equal to or less than a second predetermined value. An electrode manufacturing method,
A step of manufacturing a positive electrode sheet by attaching a positive electrode active material to a sheet-like positive electrode material, a step of manufacturing a negative electrode sheet by attaching a negative electrode active material to a sheet-like negative electrode material, and a positive electrode sheet and a negative electrode via a separator A step of manufacturing a wound body by winding a sheet, a step of drying the wound body, a step of deriving a weight reduction rate of the wound body during the drying process, and drying based on the derived weight reduction rate The electrode manufacturing method provided with the process of complete | finishing a process.   The step of drying the positive electrode sheet after the positive electrode sheet manufacturing step and before the wound body manufacturing step, and the step of drying the negative electrode sheet after the negative electrode sheet manufacturing step and before the wound body manufacturing step The electrode manufacturing method according to claim 4, further comprising the step of: An electrode manufacturing method,
A step of manufacturing a positive electrode sheet by attaching a positive electrode active material to a sheet-like positive electrode material, a positive electrode drying step of drying the positive electrode sheet, a step of deriving a weight reduction rate of the positive electrode sheet during the positive electrode drying step, and a positive electrode sheet A positive electrode drying end step for ending the positive electrode drying step based on the weight reduction rate of the step, a step of manufacturing a negative electrode sheet by attaching a negative electrode active material to a sheet-like negative electrode material, a negative electrode drying step of drying the negative electrode sheet, A step of deriving a weight reduction rate of the negative electrode sheet during the negative electrode drying step, a negative electrode drying end step of ending the negative electrode drying step based on the weight reduction rate of the negative electrode sheet, a separator after the positive electrode drying end step and the negative electrode drying end step A step of producing a wound body by winding the positive electrode sheet and the negative electrode sheet via,
The wound body manufacturing process is performed under a dry atmosphere. A first press step of pressing the positive electrode sheet after the positive electrode drying end step and before the wound body manufacturing step; and a negative electrode after the negative electrode drying end step and before the wound body manufacturing step. A second pressing step of pressing the sheet,
The electrode manufacturing method according to claim 6, wherein the first pressing step and the second pressing step are performed under a dry atmosphere.   The electrode manufacturing method according to claim 1, wherein the electrode manufacturing method is used for a battery using a non-aqueous electrolyte. A device for drying the electrodes,
A drying furnace, an apparatus for measuring the weight of the electrode in the drying furnace, an apparatus for calculating a weight reduction rate of the electrode during drying from the measured weight, and stopping the drying furnace based on the calculated weight reduction rate Electrode drying apparatus comprising the apparatus.

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