Doping system and method for manufacturing electrodes

Abstract

A doping system that dopes, with an alkali metal, an active material included in an electrode. The doping system comprises a dope tank, a conveying unit, a connection unit, and a drying unit. The dope tank accommodates a counter electrode unit and a solution that contains ions of the alkali metal. The conveying unit conveys the electrode along a route that passes inside the dope tank. The connection unit has an electroconductive power supply roller that contacts the electrode, the connection unit electrically connecting the electrode and the counter electrode unit. The drying unit blows a gas onto the electrode that has passed inside the dope tank and is being conveyed to the power supply roller.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This international application claims priority based on Japanese Patent Application No. 2020-017198, filed with the Japan Patent Office on February 4, 2020, the entire contents of which are incorporated herein by reference. [Technical field]

[0002] The present disclosure relates to a doping system and a method for manufacturing an electrode. [Background technology]

[0003] In recent years, electronic devices have become increasingly smaller and lighter, and this has led to an increased demand for smaller and lighter batteries used as the power source for these electronic devices.

[0004] In order to satisfy such demands for miniaturization and weight reduction, non-aqueous electrolyte secondary batteries, such as lithium ion secondary batteries, have been developed. In addition, lithium ion capacitors are known as power storage devices that can be used in applications that require high energy density and high output. Furthermore, sodium ion batteries and capacitors are also known that use sodium, which is less expensive and more abundant than lithium.

[0005] In such batteries and capacitors, a process of doping an electrode with an alkali metal in advance (generally called pre-doping) is adopted for various purposes. Various methods are known for pre-doping an electrode with an alkali metal. For example, Patent Documents 1 and 2 disclose a so-called sheet-type method in which a cut electrode plate and an alkali metal plate are placed in an electrolyte via a separator and pre-doped. On the other hand, Patent Documents 3 to 6 disclose a so-called continuous method in which a strip-shaped electrode plate is transferred in the electrolyte and pre-doped. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-293499 [Patent Document 2] JP 2012-69894 A [Patent Document 3] Japanese Patent Application Publication No. 10-308212 [Patent Document 4] JP 2008-77963 A [Patent Document 5] JP 2012-49543 A [Patent Document 6] JP 2012-49544 A Summary of the Invention [Problem to be solved by the invention]

[0007] When pre-doping is performed by the methods described in Patent Documents 3 to 6, it is possible to bring the electrode and the power feed roller into contact with each other, and further to electrically connect the power feed roller and the counter electrode unit.

[0008] The dope solution adheres to the electrodes that have passed through the dope tank. When the electrodes with the dope solution adhered to them come into contact with the power feed roller, a reaction occurs on the power feed roller, and alkali metals are precipitated on the surface of the power feed roller. The resistance between the power feed roller with alkali metals precipitated on its surface and the electrodes is high. Therefore, if pre-doping is continued using a power feed roller with alkali metals precipitated on its surface, the quality of the electrodes may deteriorate.

[0009] When the electrode is conveyed at a high speed, a large amount of the dope solution is likely to adhere to the electrode. Therefore, when the electrode is conveyed at a high speed, the deposition of alkali metals on the surface of the power supply roller is likely to occur. If the frequency of replacing the power supply roller on which alkali metals have been deposited increases, the productivity of the electrodes may decrease.

[0010] In one aspect of the present disclosure, it is preferable to provide a doping system and an electrode manufacturing method capable of suppressing deposition of an alkali metal on the surface of a power feed roller. [Means for solving the problem]

[0011] One aspect of the present disclosure is a doping system configured to dope an active material contained in an electrode with an alkali metal. The doping system includes a doping tank configured to accommodate a solution containing ions of an alkali metal and a counter electrode unit, a transport unit configured to transport the electrode along a path passing through the doping tank, a connection unit having a conductive current supply roller in contact with the electrode and configured to electrically connect the electrode and the counter electrode unit, and a drying unit configured to blow a gas onto the electrode passing through the doping tank and being transported to the current supply roller.

[0012] The doping system according to one aspect of the present disclosure can blow gas onto the electrode passing through a dope tank and being transported to the power supply roller to dry it, thereby preventing alkali metal from being deposited on the surface of the power supply roller.

[0013] Another aspect of the present disclosure is a method for producing an electrode including an active material doped with an alkali metal. In the method for producing an electrode that is another aspect of the present disclosure, an electrode including an active material is transported along a path that passes through a doping tank that contains a solution including an alkali metal ion and a counter electrode unit, the electrode that has passed through the doping tank is dried, and the dried electrode and the counter electrode unit are electrically connected to each other.

[0014] According to the method for producing an electrode according to another aspect of the present disclosure, the electrode to which the dope solution is attached can be prevented from being electrically connected to the counter electrode unit, and therefore, deposition of alkali metal on the surface of a member in contact with the electrode can be prevented.

[0015] Another aspect of the present disclosure is a doping system configured to dope an active material contained in an electrode with an alkali metal. The doping system includes a doping tank configured to accommodate a solution containing ions of an alkali metal and a counter electrode unit, a transport unit configured to transport the electrode along a path passing through the doping tank, a connection unit having a conductive power supply roller in contact with the electrode and configured to electrically connect the electrode and the counter electrode unit, a main body of the doping system insulated from the doping tank, and a power source configured to connect to the power supply roller. The potential of a terminal of the power source connected to the power supply roller is lower than the potential of a terminal of the power source connected to the main body.

[0016] The doping system according to another aspect of the present disclosure can suppress the deposition of alkali metals on the surface of the doping bath. When the deposition of alkali metals on the surface of the doping bath is suppressed, the pre-doping is easily stabilized, and it is easy to manufacture a high-quality electrode. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is an explanatory diagram showing a configuration of a doping system. [Diagram 2] FIG. 2 is an explanatory diagram showing a configuration of a doping tank when the doping system has a first electrical configuration. [Diagram 3] FIG. 13 is an explanatory diagram showing the configuration of a doping tank when the doping system has a second electrical configuration. [Figure 4] FIG. 13 is an explanatory diagram showing the configuration of a doping tank when the doping system has a third electrical configuration. [Diagram 5] FIG. 2 is an explanatory diagram showing the configuration of a counter electrode unit. [Figure 6] FIG. 2 is an explanatory diagram showing the configuration of the drying system as viewed from above. [Figure 7] FIG. 2 is an explanatory diagram illustrating the configuration of the drying system as viewed from the front side in FIG. [Figure 8]FIG. 2 is an explanatory diagram illustrating the configuration of the drying system as viewed from the right side in FIG. [Figure 9] FIG. 2 is an explanatory diagram illustrating the configuration of the drying system as viewed from the rear side in FIG. [Figure 10] FIG. 2 is an explanatory diagram showing the configuration of a first blower having a plurality of openings arranged in a straight line. [Figure 11] 11 is a cross-sectional view taken along line XI-XI in FIG. 10. [Figure 12] FIG. 4 is an explanatory diagram illustrating the configuration of a first blower having a slit-shaped opening. [Figure 13] 13 is a cross-sectional view taken along line XIII-XIII in FIG. 12. [Figure 14] 10 is an explanatory diagram showing the configuration of a first blower having a plurality of openings whose positions in the circumferential direction are alternately different. FIG. [Figure 15] 15 is a cross-sectional view taken along the line XV-XV in FIG. 14. [Figure 16] FIG. 2 is a plan view showing the configuration of an electrode. [Figure 17] 17 is a cross-sectional view taken along the line XVII-XVII in FIG. 16. [Explanation of symbols]

[0018] 1...electrode, 1A...doping electrode, 11...doping system, 15, 17, 19...doping tank, 21, 23...cleaning tank, 25, 27, 29, 31, 33, 65, 67, 69, 70, 35, 37, 39, 40, 41, 43, 45, 46, 47, 49, 51, 52, 53, 55, 57, 58, 59, 61, 64, 71, 73, 75, 77, 79, 81, 83 , 85, 87, 89, 91, 93...conveyor rollers, 94...active material layer unformed portion, 96...center portion, 101...supply roll, 103...winding roll, 105...support base, 107...circulation filtration unit, 109, 110, 111, 112, 113, 114...power source, 109A...first terminal, 109B...second terminal, 110A...first terminal, 110B...second terminal, 117...tab Cleaner, 119... recovery unit, 121... end sensor, 123, 135... partition plate, 125, 127, 145, 147... support rod, 131... upstream tank, 133... downstream tank, 137, 139, 141, 143... counter electrode unit, 149, 151... space, 153... conductive base material, 155... alkali metal-containing plate, 157... porous insulating member, 161... filter, 1 63...pump, 165...piping, 193...current collector, 195...active material layer, 201A to F...drying unit, 203...apparatus housing, 205...insulating plate, 207...small power source, 209...resistor, 210...diode, 211...base portion, 213...first blower, 215...second blower, 217...connection portion, 219...first surface, 221...second surface, 223...opening, 225...gas DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Exemplary embodiments of the present disclosure will now be described with reference to the drawings. First Embodiment 1. Configuration of the doping system 11 The doping system 11 dopes an active material contained in an electrode 1, which will be described later, with an alkali metal. The configuration of the doping system 11 will be described with reference to Figs. 1 to 5. As shown in Fig. 1, the doping system 11 includes doping tanks 15, 17, and 19, cleaning tanks 21 and 23, and conveying rollers 25, 27, 29, 31, 33, 65, 67, 69, 70, 35, 37, 39, 40, 41, 43, 45, 46, 47, 49, 51, 52, 53, 55, 57, 58, 59, 61, 64, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 9 The conveying roller group corresponds to the conveying unit.

[0020] The configuration of the dope tank 17 will be described with reference to Fig. 2 to Fig. 4. The dope tank 17 is composed of an upstream tank 131 and a downstream tank 133. The upstream tank 131 is disposed on the side of the supply roll 101 (hereinafter referred to as the upstream side), and the downstream tank 133 is disposed on the side of the take-up roll 103 (hereinafter referred to as the downstream side).

[0021] First, the configuration of the upstream tank 131 will be described. The upstream tank 131 is a rectangular tank that is open at the top. The bottom surface of the upstream tank 131 has a substantially U-shaped cross section. The upstream tank 131 includes a partition plate 135. The upstream tank 131 also contains four counter electrode units 137, 139, 141, and 143.

[0022] The partition plate 135 is supported by a support rod 145 that passes through its upper end. The support rod 145 is fixed to a wall or the like (not shown). The partition plate 135 extends in the vertical direction and divides the interior of the upstream tank 131 into two spaces. The transport roller 40 is attached to the lower end of the partition plate 135. The partition plate 135 and the transport roller 40 are supported by a support rod 147 that passes through them. The partition plate 135 is cut out near its lower end so as not to come into contact with the transport roller 40. A space exists between the transport roller 40 and the bottom surface of the upstream tank 131.

[0023] The counter electrode unit 137 is accommodated on the upstream side of the upstream tank 131. The counter electrode units 139 and 141 are arranged to sandwich the partition plate 135 from both sides. The counter electrode unit 143 is accommodated on the downstream side of the upstream tank 131.

[0024] A space 149 exists between the counter electrode unit 137 and the counter electrode unit 139. A space 151 exists between the counter electrode unit 141 and the counter electrode unit 143. The counter electrode units 137, 139, 141, and 143 have the same configuration. Here, the configurations of the counter electrode units 137 and 139 will be described with reference to FIG. 5.

[0025] The counter electrode units 137 and 139 have a configuration in which a conductive base material 153, an alkali metal-containing plate 155, and a porous insulating member 157 are laminated. Examples of the material of the conductive base material 153 include copper, stainless steel, and nickel. The form of the alkali metal-containing plate 155 is not particularly limited, and examples of the form include an alkali metal plate and an alkali metal alloy plate. The thickness of the alkali metal-containing plate 155 is, for example, 0.03 to 6 mm.

[0026] The porous insulating member 157 has a plate-like shape. The porous insulating member 157 is layered on the alkali metal-containing plate 155. The plate-like shape of the porous insulating member 157 is the shape of the porous insulating member 157 when it is layered on the alkali metal-containing plate 155. The porous insulating member 157 may be a member that maintains a certain shape by itself, or may be a member that is easily deformable, such as a net.

[0027] The porous insulating member 157 is porous. Therefore, a doping solution, which will be described later, can pass through the porous insulating member 157. This allows the alkali metal-containing plate 155 to come into contact with the doping solution.

[0028] The porous insulating member 157 may be, for example, a mesh made of resin. Examples of resins include polyethylene, polypropylene, nylon, polyether ether ketone, and polytetrafluoroethylene. The mesh opening can be set appropriately. The mesh opening is, for example, 0.1 μm to 10 mm, and preferably 0.1 to 5 mm. The mesh thickness can be set appropriately. The mesh thickness is, for example, 1 μm to 10 mm, and preferably 30 μm to 1 mm. The mesh opening ratio can be set appropriately. The mesh opening ratio is, for example, 5 to 98%, preferably 5 to 95%, and more preferably 50 to 95%.

[0029] The porous insulating member 157 may be made entirely of an insulating material, or may include an insulating layer in part.

[0030] The downstream tank 133 basically has the same configuration as the upstream tank 131. However, inside the downstream tank 133, a transport roller 46 is present instead of the transport roller 40.

[0031] The doping tank 17 and its surroundings have, for example, the electrical configuration shown in Fig. 2 (hereinafter referred to as a first electrical configuration). The power supplies 109 and 110 are bipolar power supplies. A first terminal 109A of the power supply 109 is connected to the transport rollers 37, 41, 43, and 47 via a cable. The transport rollers 37, 41, 43, and 47 are located above the doping tank 17. The transport rollers 37, 41, 43, and 47 are power supply rollers made of a conductive material, as described later.

[0032] The second terminal 109B of the power source 109 is connected to the counter electrode units 139, 141 housed in the upstream tank 131 and the counter electrode units 139, 141 housed in the downstream tank 133 via cables.

[0033] A first terminal 110A of the power source 110 is connected via a cable to the transport rollers 37, 41, 43, and 47. A second terminal 110B of the power source 110 is connected via a cable to the counter electrode units 137 and 143 housed in the upstream tank 131 and the counter electrode units 137 and 143 housed in the downstream tank 133.

[0034] The potential of the first terminal 109A and the potential of the first terminal 110A are both 0 V. The potential of the second terminal 109B and the potential of the second terminal 110B are both positive potentials. The positive potentials are, for example, +3 V.

[0035] The parts of the power supplies 109 and 110 whose potential is 0V are connected to the device housing 203 to create a reference potential in the first electrical configuration. In Figs. 2 to 4, "FG" means the device housing 203. The doping tank 17 is connected to the device housing 203 via an insulating plate 205. The doping tank 17 and the device body 203 are insulated from each other. The device body 203 corresponds to the main body of the doping system 11.

[0036] The doping tank 17 and its surroundings may have an electrical configuration shown in Fig. 3 (hereinafter referred to as a second electrical configuration). The second electrical configuration is basically the same as the first electrical configuration. However, in the second electrical configuration, the potentials of the first terminal 109A and the first terminal 110A are negative. The negative potential is, for example, -3V. The potentials of the second terminal 109B and the second terminal 110B are 0V.

[0037] Here, since power supply 109 and power supply 110 are bipolar power supplies, it is possible to reverse the direction of the current. In the second electrical configuration, a negative current flows from the terminal connected to the positive side of the bipolar power supply, and the potential on the negative side is set to 0V. Therefore, the sign of the voltage on the positive side terminal is negative. In FIG. 3, in order to clarify the polarity of the bipolar power supply, the direction of the symbol for the DC power supply is drawn to match the direction of the positive terminal of the bipolar power supply.

[0038] In such a second electrical configuration, the potential of the first terminal 109A and the first terminal 110A is lower than the potential of the terminal connected to the device housing 203 among the power sources 109 and 110. Therefore, the potential of the conveying rollers 37, 41, 43, and 47, which are power supply rollers, is lower than 0V. In addition, the potential of the electrode 1 in contact with the power supply roller is also lower than the doping tank 17. Since the lithium dissolved from the counter electrode units 137, 139, 141, and 143 is positively charged, it is easy to selectively move to the electrode 1 with a low potential. As a result, the deposition of lithium on the surface of the doping tank 17 having a potential near 0V is suppressed. Since the deposition of lithium on the surface of the doping tank 17 is suppressed, the pre-doping becomes stable and it becomes easy to manufacture a high-quality electrode 1.

[0039] The doping tank 17 and its surroundings may have an electrical configuration as shown in Fig. 4 (hereinafter referred to as a third electrical configuration). The third electrical configuration is basically the same as the first electrical configuration. However, in the third electrical configuration, the potential of the doping tank 17 is a positive potential. The positive potential is, for example, +4V. As a method for setting the potential of the doping tank 17 to a positive potential, for example, a method using a small power supply 207 and a resistor 209 can be used.

[0040] In such a third electrical configuration, the potential of the power source 109, the power source 110, the part connected to the device housing 203, and the potential of the first terminal 109A and the first terminal 110A are the same. As described above, the doping tank 17 is at a positive potential of, for example, +4V. Therefore, the lithium dissolved from the counter electrode units 137, 139, 141, 143 is charged to a positive potential and becomes a cation, and is easily moved to the electrode 1 at a potential near 0V. As a result, for example, the deposition of lithium on the surface of the doping tank 17 at a positive potential of +4V is suppressed, making it easier to manufacture a high-quality electrode 1.

[0041] The electrical connection paths extending from the transport rollers 37, 41, 43, and 47 through the power source 109 or the power source 110 to the counter electrode units 137, 139, 141, and 143 housed in the doping tank 17 correspond to the connection units.

[0042] The dope tank 15 basically has the same configuration as the dope tank 17. However, inside the dope tank 15, there are transport rollers 33 and 70 instead of transport rollers 40 and 46. Also, the counter electrode units 137, 139, 141, and 143 housed in the dope tank 15 are connected to power sources 113 and 114 instead of power sources 109 and 110. The power sources 113 and 114 are bipolar power sources. Also, the power sources 113 and 114 are connected to transport rollers 29, 65, 67, and 35 instead of transport rollers 37, 41, 43, and 47. The transport rollers 29, 65, 67, and 35 are located above the dope tank 15. The transport rollers 29, 65, 67, and 35 are power supply rollers made of a conductive material, as described later.

[0043] The electrical connection paths extending from the transport rollers 29, 65, 67, and 35 through the power source 113 or 114 to the counter electrode units 137, 139, 141, and 143 housed in the doping tank 15 correspond to connection units.

[0044] The dope tank 19 basically has the same configuration as the dope tank 17. However, inside the dope tank 19, transport rollers 52 and 58 exist instead of transport rollers 40 and 46. Also, the counter electrode units 137, 139, 141, and 143 housed in the dope tank 19 are connected to power supplies 111 and 112 instead of power supplies 109 and 110. The power supplies 111 and 112 are bipolar power supplies. Also, the power supplies 111 and 112 are connected to transport rollers 49, 53, 55, and 59 instead of transport rollers 37, 41, 43, and 47. The transport rollers 49, 53, 55, and 59 are located above the dope tank 19. The transport rollers 49, 53, 55, and 59 are power supply rollers made of a conductive material, as described later.

[0045] The electrical connection paths extending from the transport rollers 49, 53, 55, and 59 to the counter electrode units 137, 139, 141, and 143 housed in the doping tank 19 via the power source 111 or 112 correspond to connection units.

[0046] The cleaning tank 21 is a rectangular tank that is open at the top. The bottom surface of the cleaning tank 21 has a substantially U-shaped cross section. The cleaning tank 21 is equipped with a partition plate 123. The partition plate 123 is supported by a support rod 125 that penetrates its upper end. The support rod 125 is fixed to a wall or the like (not shown). The partition plate 123 extends in the vertical direction, and divides the interior of the cleaning tank 21 into two spaces.

[0047] The transport roller 64 is attached to the lower end of the partition plate 123. The partition plate 123 and the transport roller 64 are supported by a support rod 127 that penetrates them. The partition plate 123 is cut out near its lower end so as not to come into contact with the transport roller 64. There is a space between the transport roller 64 and the bottom surface of the cleaning tank 21.

[0048] The cleaning tank 23 basically has the same configuration as the cleaning tank 21. However, inside the cleaning tank 23, transport rollers 75 are present instead of the transport rollers 33. The cleaning tanks 21 and 23 correspond to cleaning units.

[0049] Of the group of conveying rollers, conveying rollers 29, 31, 67, 69, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, and 59 are made of a conductive material. Conveying rollers 29, 31, 67, 69, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, and 59 correspond to conductive power supply rollers.

[0050] The other rollers in the group of conveying rollers are made of elastomer except for the bearing parts. The group of conveying rollers conveys the electrode 1 along a certain path. The path along which the group of conveying rollers conveys the electrode 1 is from the supply roll 101, through the dope tank 15, the dope tank 17, the dope tank 19, the cleaning tank 21, the cleaning tank 23, the tub cleaner 117, and finally to the take-up roll 103.

[0051] The portion of the path that passes through the dope tank 15 is as follows. First, the material is sent downward by the transport rollers 29 and 31, and moves downward through the space 149 of the upstream tank 131. Next, the transport roller 33 changes the direction of movement upward, and the material moves upward through the space 151 of the upstream tank 131. Next, the transport rollers 65 and 67 change the direction of movement downward, and the material moves downward through the space 149 of the downstream tank 133. Next, the transport roller 70 changes the direction of movement upward, and the material moves upward through the space 151 of the downstream tank 133. Finally, the transport roller 35 changes the direction of movement horizontally, and the material moves toward the dope tank 17.

[0052] The portion of the above-mentioned path that passes through the dope tank 17 is as follows. First, the moving direction is changed downward by the conveying roller 37, and the dope tank 17 moves downward through the space 149 of the upstream tank 131. Next, the moving direction is changed upward by the conveying roller 40, and the dope tank 17 moves upward through the space 151 of the upstream tank 131. Next, the moving direction is changed downward by the conveying rollers 41 and 43, and the dope tank 17 moves downward through the space 149 of the downstream tank 133. Next, the moving direction is changed upward by the conveying roller 46, and the dope tank 17 moves upward through the space 151 of the downstream tank 133. Finally, the moving direction is changed horizontally by the conveying roller 47, and the dope tank 19 moves forward.

[0053] The portion of the above-mentioned path that passes through the dope tank 19 is as follows. First, the moving direction is changed downward by the conveying roller 49, and the roller moves downward through the space 149 of the upstream tank 131. Next, the moving direction is changed upward by the conveying roller 52, and the roller moves upward through the space 151 of the upstream tank 131. Next, the moving direction is changed downward by the conveying rollers 53 and 55, and the roller moves downward through the space 149 of the downstream tank 133. Next, the moving direction is changed upward by the conveying roller 58, and the roller moves upward through the space 151 of the downstream tank 133. Finally, the moving direction is changed horizontally by the conveying roller 59, and the roller moves toward the cleaning tank 21.

[0054] In addition, in the above-mentioned path, the portion that passes through the cleaning tank 21 is a path in which the moving direction is first changed downward by the conveying roller 61 and moves downward, and then the moving direction is changed upward by the conveying roller 64.

[0055] In addition, in the above-mentioned path, the portion that passes through cleaning tank 23 is a path in which the moving direction is first changed downward by conveying roller 73 and moves downward, and then the moving direction is changed upward by conveying roller 75.

[0056] The electrode 1 is wound around the supply roll 101. That is, the supply roll 101 holds the electrode 1 in a wound state. The active material in the electrode 1 held by the supply roll 101 has not yet been doped with an alkali metal.

[0057] The group of transport rollers pulls out and transports the electrode 1 held by the supply roll 101. The winding roll 103 winds up and stores the electrode 1 transported by the group of transport rollers. The electrode 1 stored on the winding roll 103 has been pre-doped in doping tanks 15, 17, and 19. Therefore, the active material in the electrode 1 stored on the winding roll 103 is doped with an alkali metal. The electrode 1 stored on the winding roll 103 is a doped electrode 1A.

[0058] The support table 105 supports the doping tanks 15, 17, and 19 and the cleaning tanks 21 and 23 from below. The height of the support table 105 can be changed. The circulation filtration units 107 are provided in the doping tanks 15, 17, and 19, respectively. The circulation filtration units 107 include a filter 161, a pump 163, and a pipe 165.

[0059] In the circulation filtration unit 107 provided in the dope tank 17, the pipe 165 is a circulation pipe that goes out from the dope tank 17, passes through the pump 163 and the filter 161 in order, and returns to the dope tank 17. The dope solution in the dope tank 17 circulates through the pipe 165 and the filter 161 by the driving force of the pump 163, and returns to the dope tank 17 again. At this time, foreign matter in the dope solution is filtered by the filter 161. Examples of the foreign matter include foreign matter precipitated from the dope solution and foreign matter generated from the electrode 1. The material of the filter 161 is, for example, a resin such as polypropylene or polytetrafluoroethylene. The pore size of the filter 161 can be appropriately set. The pore size of the filter 161 is, for example, 0.2 μm to 50 μm.

[0060] The circulation filtration units 107 provided in the dope tanks 15 and 19 have the same configuration and provide the same functions and effects. For convenience, the dope solution is not shown in Figs.

[0061] The tub cleaner 117 cleans an active material layer unformed portion 94 of the electrode 1, which will be described later. The recovery units 119 are disposed in the dope tanks 15, 17, and 19 and the cleaning tanks 21 and 23. The recovery units 119 recover the liquid that the electrode 1 takes out of the tanks and return it to the tank.

[0062] The recovery unit 119 includes, for example, a remover roll that pressurizes the electrode 1 from both sides, and a liquid droplet guide. The liquid droplet guide returns the dope solution or cleaning solution absorbed by the remover roll to the dope tanks 15, 17, and 19 or the cleaning tanks 21 and 23.

[0063] The position of the recovery unit 119 arranged in the dope tank 15 is near the portion of the electrode 1 that passes through the upstream tank 131 of the dope tank 15 and is transported to the transport roller 65, and near the portion of the electrode 1 that passes through the downstream tank 133 of the dope tank 15 and is transported to the transport roller 35.

[0064] The position of the recovery unit 119 arranged in the dope tank 17 is near the portion of the electrode 1 that passes through the upstream tank 131 of the dope tank 17 and is transported to the transport roller 41, and near the portion of the electrode 1 that passes through the downstream tank 133 of the dope tank 17 and is transported to the transport roller 47.

[0065] The position of the recovery unit 119 arranged in the dope tank 19 is near the portion of the electrode 1 that passes through the upstream tank 131 of the dope tank 19 and is transported to the transport roller 53, and near the portion of the electrode 1 that passes through the downstream tank 133 of the dope tank 19 and is transported to the transport roller 59.

[0066] The end sensor 121 detects the position of the end of the electrode 1 in the width direction W. The doping system 11 adjusts the positions of the supply roll 101 and the take-up roll 103 in the width direction W based on the detection result of the end sensor 121. The device housing 203 accommodates other components of the doping system 11.

[0067] In this embodiment, the doping system 11 includes two cleaning tanks 21 and 23. The number of cleaning tanks may be one or three or more. When the number of cleaning tanks is two or more, it is preferable because the total amount of cleaning liquid used can be reduced.

[0068] In this embodiment, the transport path of the electrode 1 in the cleaning tanks 21 and 23 is a transport path that makes one vertical reciprocation. The transport path of the electrode 1 in the cleaning tanks 21 and 23 may be a transport path that makes two vertical reciprocations, similar to the doping tanks 15, 17, and 19.

[0069] 2. Configuration of Drying Units 201A to 201F 1, the drying unit 201A is disposed near a portion of the electrode 1 that passes through the upstream tank 131 of the dope tank 15 and is transported to the transport roller 65. The drying unit 201A is closer to the transport roller 65 than the adjacent recovery unit 119. By having the drying unit 201A closer to the transport roller 65 than the recovery unit 119, deposition of alkali metal on the surface of the power supply roller can be further suppressed.

[0070] The drying unit 201B is disposed near a portion of the electrode 1 that passes through the downstream tank 133 of the dope tank 15 and is transported to the transport rollers 35. The drying unit 201B is located closer to the transport rollers 35 than the adjacent recovery unit 119.

[0071] The drying unit 201C is disposed near a portion of the electrode 1 that passes through the upstream tank 131 of the dope tank 17 and is transported to the transport rollers 41. The drying unit 201C is closer to the transport rollers 41 than the adjacent recovery unit 119.

[0072] The drying unit 201D is disposed near a portion of the electrode 1 that passes through the downstream tank 133 of the dope tank 17 and is transported to the transport roller 47. The drying unit 201D is closer to the transport roller 47 than the adjacent recovery unit 119.

[0073] The drying unit 201E is disposed near a portion of the electrode 1 that passes through the upstream tank 131 of the dope tank 19 and is transported to the transport rollers 53. The drying unit 201E is located closer to the transport rollers 53 than the adjacent recovery unit 119.

[0074] The drying unit 201F is disposed near a portion of the electrode 1 that passes through the downstream tank 133 of the dope tank 19 and is transported to the transport roller 59. The drying unit 201F is closer to the transport roller 59 than the adjacent recovery unit 119.

[0075] The drying units 201A to 201F have the same configuration. Here, the configuration of the drying unit 201C will be described with reference to Figures 2 to 4 and 6 to 15. As shown in Figures 6 to 9, the drying unit 201C includes a base portion 211, a first blower 213, and a second blower 215.

[0076] The base part 211 has a basic box-like shape. The base part 211 includes a connection part 217. The drying unit 201C is fixed to a support part (not shown) via the connection part 217. The drying unit 201C does not contact other members except the connection part 217. The support part and the drying unit 201C are electrically insulated by the connection part 217. By including the connection part 217, even if the first blower 213 or the second blower 215 contacts the electrode 1, it is possible to suppress a short circuit between the electrode 1 and the support part. The material of the connection part 217 is not particularly limited as long as it is a material that can insulate the support part and the drying unit 201C. Examples of the material of the connection part 217 include epoxy glass and the like.

[0077] The first blower 213 and the second blower 215 each have a basic cylindrical shape. The first blower 213 and the second blower 215 are each attached to one surface of the base part 211. The axial direction of the first blower 213 and the axial direction of the second blower 215 are parallel to each other. As shown in Figs. 6 and 9, there is a gap between the first blower 213 and the second blower 215.

[0078] 6 and 9, in the drying unit 201C, a first blower 213 and a second blower 215 are arranged to sandwich the electrode 1 from both sides. The first blower 213 faces a surface (hereinafter referred to as a first surface 219) of the electrode 1 that will later come into contact with the transport roller 45. A gap exists between the first blower 213 and the first surface 219. The axial direction of the first blower 213 and the width direction W of the electrode 1 are parallel to each other.

[0079] The second blower 215 faces a surface (hereinafter referred to as a second surface 221) of the electrode 1 that will later come into contact with the transport rollers 41, 43, and 47. A gap exists between the second blower 215 and the second surface 221. The axial direction of the second blower 215 and the width direction W of the electrode 1 are parallel to each other.

[0080] The first blower 213 has an opening. The opening communicates the inside and outside of the first blower 213. Examples of the form of the opening include the forms shown in Figs. 10 and 11. The first blower 213 has a plurality of openings 223. Each opening 223 is a circular hole. The plurality of openings 223 are arranged at equal intervals on a straight line parallel to the axial direction of the first blower 213. The positions of the plurality of openings 223 in the circumferential direction C are the same. As shown in Fig. 11, the plurality of openings 223 face the electrode 1.

[0081] 12 and 13 show examples of the shape of the opening. The first blower 213 has one slit-shaped opening 223. The slit-shaped opening 223 extends along the axial direction of the first blower 213. As shown in FIG. 13, the slit-shaped opening 223 faces the electrode 1.

[0082] As the form of the openings, for example, there are forms shown in Figs. 14 and 15. The first blower 213 has a plurality of openings 223. Each opening 223 is a circular hole. The plurality of openings 223 are arranged at equal intervals along the axial direction of the first blower 213. There are two types of positions of the plurality of openings 223 in the circumferential direction C. The position of any opening 223 in the circumferential direction C is different from the position of an adjacent opening 223 in the circumferential direction C. As shown in Fig. 15, the plurality of openings 223 face the electrode 1.

[0083] The second blower 215 has a similar form to the first blower 213. Examples of the material of the first blower 213 and the second blower 215 include resin. Examples of the resin include at least one selected from the group consisting of polyolefin resin, polyester resin, polyarylate resin, polyurethane resin, polyurethane resin, polycarbonate resin, polyamide resin, polyimide resin, polyphenylene sulfide resin, and fluorine-based resin. When the material of the first blower 213 and the second blower 215 is resin, it is possible to suppress a short circuit between the first blower 213 or the second blower 215 and the electrode 1. When the surface material of the first blower 213 and the second blower 215 is resin, it is possible to further suppress a short circuit between the first blower 213 or the second blower 215 and the electrode 1.

[0084] The material of the first blower 213 and the second blower 215 may be at least one selected from the group consisting of metals, alloys of two or more metals, oxides of metals or alloys, and nitrides of metals or alloys. When the first blower 213 and the second blower 215 are made of the above-mentioned materials, they are excellent in terms of workability and strength.

[0085] A gas supply path is provided that runs from a gas supply source (not shown) through the inside of base portion 211 to the inside of first blower 213 and second blower 215. As shown in Figures 11, 13 and 15, first blower 213 blows gas 225 supplied through the gas supply path from opening 223 onto first surface 219.

[0086] Further, the second blower 215 blows the gas supplied through the gas supply path from the opening 223 onto the second surface 221. Thus, the drying unit 201C uses the first blower 213 and the second blower 215 to blow gas onto the electrode 1 passing through the dope tank 17 and being transported to the transport roller 41.

[0087] Since the first blower 213 and the second blower 215 blow gas onto the surface of the electrode 1, for example, when the electrode 1 reaches the transport roller 41, the electrode 1 is dry. As a result, deposition of an alkali metal on the surface of the transport roller 41 can be suppressed.

[0088] When the first blower 213 and the second blower 215 have a plurality of openings 223, it is preferable that there is little variation in the gas flow rate among the plurality of openings 223. In particular, it is preferable that there is little difference in the gas flow rate between the openings 223 on the base side and the openings 223 on the tip side in the first blower 213 and the second blower 215.

[0089] When the first blower 213 and the second blower 215 have a slit-shaped opening 223, it is preferable that the difference in gas flow rate between the base side and the tip side of the opening 223 is small.

[0090] The gas may be, for example, at least one selected from the group consisting of argon gas, helium gas, neon gas, nitrogen gas, carbon dioxide gas, and dehumidified air from which moisture has been removed. When the above gas is used, the reaction between the gas and the active material can be suppressed. In addition, when the above gas is used, the oxygen concentration inside the device housing 203 can be reduced, so that the device has excellent explosion-proof properties.

[0091] 1 to 4, the doping system 11 includes one drying unit 201C. The doping system 11 may include, for example, a plurality of drying units 201C. Each of the plurality of drying units 201C is located near a portion of the electrode 1 that passes through the upstream tank 131 of the dope tank 17 and is transported to the transport roller 41. The plurality of drying units 201C are arranged along the longitudinal direction of the electrode 1.

[0092] The drying units 201A, B, D to F have the same configuration as the drying unit 201C and provide the same effects, except that the drying units 201A, B, D to F blow gas onto the portions of the electrode 1 that are in their respective vicinity to dry them.

[0093] For example, exhaust nozzles can be installed near the drying units 201A to F. When exhaust nozzles are installed, the electrode 1 can be dried more efficiently.

[0094] 3. Construction of Electrode 1 The structure of electrode 1 will be described with reference to Figures 16 and 17. Electrode 1 has a strip-like shape as shown in Figure 16. Electrode 1 includes a strip-like current collector 193 and active material layers 195 formed on both sides thereof as shown in Figure 17.

[0095] At both ends in the width direction W of the electrode 1, there are active material layer unformed portions 94. In the active material layer unformed portions 94, active material layer 195 is not formed on current collector 193, and current collector 193 is exposed. As shown in FIG. 16, active material layer unformed portions 94 exist continuously with a constant width along the longitudinal direction of electrode 1. Active material layer unformed portions 94 exist on both sides of electrode 1. A portion of electrode 1 where active material layer 195 is formed is defined as central portion 96. Central portion 96 is located at the center of electrode 1 in the width direction. Central portion 96 exists continuously with a constant width along the longitudinal direction of electrode 1. Note that electrode 1 may have active material layer unformed portion 94 only at one end in the width direction.

[0096] When the current collector 193 is a positive electrode current collector, aluminum, stainless steel, or the like is preferable. When the current collector 193 is a negative electrode current collector, metal foil such as copper, nickel, stainless steel, or the like is preferable. Moreover, the current collector 193 may be a metal foil on which a conductive layer mainly composed of a carbon material is formed. The thickness of the current collector 193 is, for example, 5 to 50 μm.

[0097] Active material layer 195 can be produced, for example, by preparing a slurry containing an active material before being doped with an alkali metal, a binder, and the like, and then applying this slurry onto current collector 193 and drying it.

[0098] Examples of binders include rubber-based binders such as styrene-butadiene rubber (SBR) and NBR; fluorine-based resins such as polytetrafluoroethylene and polyvinylidene fluoride; polypropylene, polyethylene, polyimide, and fluorine-modified (meth)acrylic binders as disclosed in JP-A-2009-246137.

[0099] The slurry may contain other components in addition to the active material and the binder. Examples of the other components include a conductive agent and a thickener. Examples of the conductive agent include carbon black, graphite, vapor-grown carbon fiber, and metal powder. Examples of the thickener include carboxymethylcellulose, its Na salt or ammonium salt, methylcellulose, hydroxymethylcellulose, ethylcellulose, hydroxypropylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, and casein.

[0100] There is no particular limitation on the thickness of active material layer 195. The thickness of active material layer 195 is, for example, 5 to 500 μm, preferably 10 to 200 μm, and particularly preferably 10 to 100 μm.

[0101] The active material contained in active material layer 195 is not particularly limited as long as it is an electrode active material applicable to a battery or capacitor that utilizes the insertion / extraction of alkali metal ions, and may be either a negative electrode active material or a positive electrode active material.

[0102] The negative electrode active material is not particularly limited. Examples of the negative electrode active material include carbon materials. Examples of the negative electrode active material include materials containing metals or semimetals such as Si and Sn that can be alloyed with lithium, or oxides thereof. Examples of the carbon material include graphite, graphitizable carbon, non-graphitizable carbon, and composite carbon materials. Composite carbon materials are, for example, materials in which graphite particles are coated with carbides of pitch or resin. Specific examples of the carbon material include the carbon materials described in JP-A-2013-258392. Specific examples of materials containing metals or semimetals that can be alloyed with lithium, or oxides thereof, include materials described in JP-A-2005-123175 and JP-A-2006-107795.

[0103] Examples of the positive electrode active material include transition metal oxides and sulfur-based active materials. Examples of the transition metal oxide include cobalt oxide, nickel oxide, manganese oxide, vanadium oxide, and the like. Examples of the sulfur-based active material include simple sulfur and metal sulfides. Both the positive electrode active material and the negative electrode active material may be made of a single material or may be made of a mixture of two or more materials. The doping system 11 of the present disclosure is suitable for doping an alkali metal into a negative electrode active material, and it is particularly preferable that the negative electrode active material is a carbon material or a material containing Si or an oxide thereof.

[0104] The alkali metal to be doped into the active material is preferably lithium or sodium, and particularly preferably lithium.

[0105] When electrode 1 is used for producing a lithium ion secondary battery, active material layer 195 preferably has a density of 1.50 to 2.00 g / cc, and particularly preferably 1.60 to 1.90 g / cc. On the other hand, when electrode 1 is used for producing a lithium ion capacitor, active material layer 195 preferably has a density of 0.50 to 1.50 g / cc, and particularly preferably 0.70 to 1.20 g / cc.

[0106] When the electrode manufacturing method described later is not performed, the active material is not doped with an alkali metal. By performing the electrode manufacturing method described later, the active material is doped with an alkali metal. An electrode 1 in which an active material is doped with an alkali metal is a doped electrode 1A. The doped electrode 1A corresponds to an electrode containing an active material doped with an alkali metal.

[0107] 4. Composition of the dope solution When the doping system 11 is used, the dope tanks 15, 17, and 19 contain a dope solution. The dope solution includes an alkali metal salt and a first aprotic solvent. In the dope solution, a part of the alkali metal salt is ionized to generate alkali ions. The dope solution corresponds to a solution containing ions of an alkali metal. As the first aprotic solvent, an organic solvent having a boiling point of more than 150° C. at 1 atmosphere is preferable, and an organic solvent having a boiling point of more than 200° C. at 1 atmosphere is particularly preferable.

[0108] Examples of the first aprotic solvent include ethylene carbonate, propylene carbonate, butylene carbonate, 1-fluoroethylene carbonate, dipropyl carbonate, γ-butyrolactone, sulfolane, diethylene glycol dimethyl ether (diglyme), diethylene glycol methyl ethyl ether, triethylene glycol dimethyl ether (triglyme), triethylene glycol butyl methyl ether, and tetraethylene glycol dimethyl ether (tetraglyme).

[0109] In addition, as the first aprotic solvent, an ionic liquid such as a quaternary imidazolium salt, a quaternary pyridinium salt, a quaternary pyrrolidinium salt, a quaternary piperidinium salt, etc. can also be used. The first aprotic solvent may be composed of a single component, or may be a mixed solvent of two or more components.

[0110] When the first aprotic solvent is an organic solvent having a boiling point of more than 150° C. at 1 atmospheric pressure, the dope solution may contain a solvent having a boiling point of 150° C. or less at 1 atmospheric pressure. The solvent having a boiling point of 150° C. or less at 1 atmospheric pressure is preferably an aprotic organic solvent, and specific examples thereof include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, acetonitrile, dimethoxyethane, tetrahydrofuran, dioxolane, and methylene chloride.

[0111] Among these, dimethyl carbonate and ethyl methyl carbonate are preferred, and dimethyl carbonate is particularly preferred. The content of the solvent having a boiling point of 150° C. or less at 1 atmospheric pressure is preferably 50 to 90% by volume, and particularly preferably 65 to 75% by volume, of the solvent contained in the dope solution.

[0112] The alkali metal salt contained in the dope solution is preferably a lithium salt or a sodium salt. The anion moiety constituting the alkali metal salt is, for example, PF6 - , PF3(C2F5)3 - , PF3(CF3)3 - , etc. Phosphorus anion with a fluoro group; BF4 - , BF2(CF)2 - , BF3(CF3) - , B(CN)4 - Boron anions with fluoro or cyano groups such as N(FSO2)2 - , N(CF3SO2)2 - , N(C2F5SO2)2 - Sulfonylimide anions with fluoro groups such as CF3SO3 -The alkali metal salt is preferably a fluorine-containing compound.

[0113] The concentration of the alkali metal salt in the doping solution is preferably 0.1 mol / L or more, and more preferably within the range of 0.5 to 1.5 mol / L. When the concentration of the alkali metal salt in the doping solution is within this range, doping of the alkali metal proceeds efficiently.

[0114] The dope solution may further contain additives such as vinylene carbonate, vinyl ethylene carbonate, 1-fluoroethylene carbonate, 1-(trifluoromethyl)ethylene carbonate, succinic anhydride, maleic anhydride, propane sultone, and diethyl sulfone.

[0115] 5. Electrode manufacturing method When the doped electrode 1A is manufactured using the doping system 11, the following steps are first performed as preparations for manufacturing the doped electrode 1A. The electrode 1, whose active material has not yet been doped with an alkali metal, is wound around the supply roll 101. The doping tanks 15, 17, and 19 are filled with a doping solution. The doping solution is as described above in "4. Composition of the doping solution."

[0116] Next, the electrode 1 is transported along the above-mentioned path from the supply roll 101 to the take-up roll 103 by a group of transport rollers. The path along which the electrode 1 is transported passes through the doping tanks 15, 17, and 19. When the electrode 1 passes through the doping tanks 15, 17, and 19, the active material contained in the active material layer 195 is doped with an alkali metal. As a result, the electrode 1 becomes a doped electrode 1A.

[0117] Furthermore, the group of transport rollers transports the doped electrode 1A to the cleaning tanks 21 and 23. The doped electrode 1A is cleaned in the cleaning tanks 21 and 23 while being transported by the group of transport rollers.

[0118] Furthermore, the group of transport rollers continuously transports the doped electrode 1A to a tub cleaner 117. The tub cleaner 117 cleans a portion 94 of the doped electrode 1A where an active material layer is not formed.

[0119] When the electrode 1 passes through the upstream tank 131 of the dope tank 15 and is transported to the transport rollers 65, first, a part of the dope solution adhering to the electrode 1 is collected by the collection unit 119. Next, the electrode 1 is dried by being blown with gas by the drying unit 201A. When the electrode 1 reaches the transport rollers 65, it is in a dry state.

[0120] When the electrode 1 passes through the downstream tank 133 of the dope tank 15 and is transported to the transport rollers 35, first, a part of the dope solution adhering to the electrode 1 is collected by the collection unit 119. Next, the electrode 1 is dried by being blown with gas by the drying unit 201B. When the electrode 1 reaches the transport rollers 35, it is in a dry state.

[0121] When the electrode 1 passes through the upstream tank 131 of the dope tank 17 and is transported to the transport rollers 41, first, a part of the dope solution adhering to the electrode 1 is collected by the collection unit 119. Next, the electrode 1 is dried by being blown with gas by the drying unit 201C. When the electrode 1 reaches the transport rollers 41, the electrode 1 is in a dry state.

[0122] When the electrode 1 passes through the downstream tank 133 of the dope tank 17 and is transported to the transport rollers 47, first, a part of the dope solution adhering to the electrode 1 is collected by the collection unit 119. Next, the electrode 1 is dried by being blown with gas by the drying unit 201D. When the electrode 1 reaches the transport rollers 47, it is in a dry state.

[0123] When the electrode 1 passes through the upstream tank 131 of the dope tank 19 and is transported to the transport rollers 53, first, a part of the dope solution adhering to the electrode 1 is collected by the collection unit 119. Next, the electrode 1 is dried by being blown with gas by the drying unit 201E. When the electrode 1 reaches the transport rollers 53, it is in a dry state.

[0124] When the electrode 1 passes through the downstream tank 133 of the dope tank 19 and is transported to the transport rollers 59, first, a part of the dope solution adhering to the electrode 1 is collected by the collection unit 119. Next, the electrode 1 is dried by being blown with gas by the drying unit 201F. When the electrode 1 reaches the transport rollers 59, it is in a dry state.

[0125] The flow rate of the gas is not particularly limited. The higher the flow rate of the gas, the easier it is to dry the electrode 1. The higher the temperature of the gas, the easier it is to dry the electrode 1. However, in the case of a gas that may react with the doped electrode 1A, such as nitrogen gas or carbon dioxide gas, the gas temperature is preferably 40° C. or lower.

[0126] As described above, in the electrode manufacturing method of the present disclosure, the electrode 1 after drying is brought into contact with the power supply roller, which makes it possible to prevent the deposition of alkali metal on the surface of the power supply roller.

[0127] In the electrode manufacturing method of the present disclosure, the electrode 1 is dried using the first blower 213 and the second blower 215 that blow gas onto the electrode 1. This makes it even easier to dry the electrode 1.

[0128] In the electrode manufacturing method of the present disclosure, the second blower 215 blows gas onto the surface of the electrode 1 that will later come into contact with the power feed roller, thereby drying it. As a result, the electrode manufacturing method of the present disclosure can further suppress the deposition of alkali metal on the surface of the power feed roller.

[0129] The first blower 213 and the second blower 215 are disposed so as to sandwich the electrode 1. Therefore, the first blower 213 and the second blower 215 can blow gas onto both sides of the electrode 1, thereby drying both sides of the electrode 1.

[0130] The first blower 213 and the second blower 215 are provided with, for example, a slit-shaped opening 223 as shown in Fig. 12. In this case, the effect of the first blower 213 and the second blower 215 in drying the surface of the electrode 1 is further enhanced.

[0131] The first blower 213 and the second blower 215 include two or more openings 223, for example, as shown in Fig. 10 or 14. In this case, the first blower 213 and the second blower 215 can more effectively dry the surface of the electrode 1.

[0132] In particular, when gas is blown in two or more directions as viewed from the axial direction of the first blower 213 and the second blower 215 as shown in Figures 14 and 15, the effect of the first blower 213 and the second blower 215 in drying the surface of the electrode 1 is even greater.

[0133] The doping system 11 is suitable for manufacturing a negative electrode for an alkaline ion type capacitor or battery, more suitable for manufacturing a negative electrode for an alkaline ion type capacitor or secondary battery, and particularly suitable for manufacturing a negative electrode for a lithium ion capacitor or lithium ion secondary battery.

[0134] The doping amount of the alkali metal is preferably 70 to 95% of the theoretical capacity of the negative electrode active material when lithium is absorbed in the negative electrode active material of a lithium ion capacitor, and is preferably 10 to 30% of the theoretical capacity of the negative electrode active material when lithium is absorbed in the negative electrode active material of a lithium ion secondary battery.

[0135] 6. Manufacturing method of electricity storage device The method for producing an electricity storage device according to the present disclosure is a method for producing an electricity storage device including a positive electrode, a negative electrode, and an electrolyte. In the method for producing an electricity storage device according to the present disclosure, the negative electrode is produced by the above "5. Method for producing an electrode".

[0136] Examples of the power storage device include a capacitor and a battery. The capacitor is not particularly limited as long as it is a capacitor that utilizes the insertion / extraction of alkali metal ions. Examples of the capacitor include a lithium ion capacitor and a sodium ion capacitor. Among them, a lithium ion capacitor is preferable.

[0137] The basic structure of the positive electrode constituting the capacitor can be a general structure, and it is preferable to use activated carbon as the positive electrode active material.

[0138] The electrolyte constituting the capacitor is usually in the form of a liquid electrolytic solution. The basic composition of the electrolytic solution is the same as that of the dope solution described above. The concentration of the alkali metal ion in the electrolyte is preferably 0.1 mol / L or more, more preferably within the range of 0.5 to 1.5 mol / L. The electrolyte may be in the form of a gel or solid in order to prevent leakage.

[0139] The capacitor may include a separator between the positive electrode and the negative electrode to prevent physical contact between them. Examples of the separator include nonwoven fabrics or porous films made of cellulose rayon, polyethylene, polypropylene, polyamide, polyester, polyimide, or the like.

[0140] An example of the capacitor structure is a stacked cell in which three or more plate-like constituent units each consisting of a positive electrode, a negative electrode, and a separator therebetween are stacked to form a laminate, and the laminate is then sealed in an exterior film.

[0141] Further, examples of the capacitor structure include a wound cell in which a strip-shaped structural unit consisting of a positive electrode, a negative electrode, and a separator therebetween is wound to form a laminate, and the laminate is housed in a rectangular or cylindrical container.

[0142] A capacitor can be manufactured, for example, by forming a basic structure including at least a negative electrode and a positive electrode, and injecting an electrolyte into the basic structure.

[0143] In the case of a lithium ion capacitor, the density of active material layer 195 is preferably 0.50 to 1.50 g / cc, and particularly preferably 0.70 to 1.20 g / cc.

[0144] The battery is not particularly limited as long as it utilizes the insertion / extraction of alkali metal ions. The battery may be a primary battery or a secondary battery. Examples of the battery include a lithium ion secondary battery, a sodium ion secondary battery, and an air battery. Among them, a lithium ion secondary battery is preferable.

[0145] The basic structure of the positive electrode constituting the battery can be a general structure. In addition to the above-mentioned examples, organic active materials such as nitroxy radical compounds and oxygen can also be used as the positive electrode active material.

[0146] The structure of the electrolyte constituting the battery and the structure of the battery itself are the same as those of the capacitor. The battery can be manufactured, for example, by forming a basic structure including at least a negative electrode and a positive electrode, and injecting an electrolyte into the basic structure. <Example> 1. Example 1 (1) Manufacturing of negative electrodes A long strip-shaped current collector 193 was prepared. The current collector 193 was used as a negative electrode current collector. The size of the current collector 193 was 132 mm in width and 8 μm in thickness. The surface roughness Ra of the current collector 193 was 0.1 μm. The current collector 193 was made of copper foil. An active material layer 195 was formed on each of both sides of the current collector 193. The active material layer 195 was a negative electrode active material layer. The thickness of the active material layer 195 was 65 μm.

[0147] The coating amount of the active material layer 195 formed on one side of the current collector 193 was 50 g / m 2 The active material layer 195 was formed along the longitudinal direction of the current collector 193. The active material layer 195 was formed over a width of 120 mm from one end of the current collector 193 in the width direction W. The width of the active material layer unformed portion 94 at the other end of the current collector 193 in the width direction W was 12 mm. Thereafter, drying and pressing were performed to obtain an electrode 1.

[0148] The active material layer 195 contained a negative electrode active material, carboxymethyl cellulose, acetylene black, and a binder in a mass ratio of 88:4:5:3. The negative electrode active material was a graphite-based active material. The binder was a fluorine acrylic resin. The graphite-based active material had a D50 of 5 μm. The graphite-based active material had a BET specific surface area of ​​10 m 2 / g.

[0149] A doping system 11 shown in FIG. 1 was prepared, and an electrode 1 was set. Also, counter electrode units 137, 139, 141, and 143 were accommodated in the doping tanks 15, 17, and 19, respectively. Next, a doping solution was supplied into the doping tanks 15, 17, and 19. The doping solution was a solution containing 1.2M LiPF6. The solvent of the doping solution was a mixed solution containing EC (ethylene carbonate) and DMC (dimethyl carbonate) in a volume ratio of 3:7.

[0150] The doping system 11 had the first electrical configuration shown in Fig. 2. The potentials of the first terminal 109A and the first terminal 110A were 0 V. The potentials of the second terminal 109B and the second terminal 110B were +3 V.

[0151] Next, while the electrode 1 was transported at a speed of 2 m / min, a current of 50 A was applied. At this time, the center in the width direction W of the active material layer 195 of the electrode 1 coincided with the center in the width direction W of the lithium metal plate of the counter electrode unit 51. When passing through the doping tanks 15, 17, and 19, the negative electrode active material in the active material layer 195 was doped with lithium at about 80% of the theoretical capacity. As a result, the electrode 1 became a doped electrode 1A.

[0152] The transported electrode 1 was dried by the above-mentioned method using the drying units 201A to F. The first blower 213 and the second blower 215 provided in the drying units 201A to F were each a pipe having a diameter of 10 mm and a length of 184 mm. The material of the first blower 213 and the second blower 215 were each SUS. SUS corresponds to metal.

[0153] The first blower 213 and the second blower 215 each had a plurality of openings 223 as shown in Figures 10 and 11. The diameter of the openings 223 was 1 mm. The number of the openings 223 was 20. The pitch of the openings 223 was 8 mm.

[0154] The first blower 213 did not blow out gas, and only the second blower 215 blew out gas. The gas was blown onto the second surface 221 by the second blower 215. The gas blown onto the electrode 1 by the second blower 215 was nitrogen gas. The flow rate of the nitrogen gas was 5 L / min throughout the second blower 215. The second surface 221 of the electrode 1 was dried by the drying units 201A-F, so that the electrode 1 was in a dry state when it came into contact with the transport rollers 65, 35, 41, 47, 53, and 59.

[0155] The doped electrode 1A was passed through doping tanks 15, 17, and 19, and then through cleaning tanks 21 and 23, where it was blown with argon to dry and then wound up. DMC at 25° C. was placed in the cleaning tanks 21 and 23. In this manner, the doped electrode 1A was produced.

[0156] (2) Dope evaluation During the pre-doping, a doping evaluation was performed. The doping evaluation is an evaluation of the ease with which the voltage increases during the pre-doping. The criteria for the doping evaluation are as follows.

[0157] AA: The absolute value of the stable voltage after pre-doping is less than 3.0V.

[0158] A: The absolute value of the stable voltage is greater than or equal to 3.0V and less than 3.3V.

[0159] B: The absolute value of the stable voltage is greater than or equal to 3.3V and less than 3.6V.

[0160] C: The voltage is above 3.6 V regardless of whether the voltage is stable during pre-doping.

[0161] The stable voltage means the voltage when the voltage change becomes ±0.05V or less after the start of pre-doping. In Example 1, the evaluation result of the doping evaluation was A, and the stable voltage was 3.05V. In Example 1, the voltage did not continuously increase during pre-doping. The results of the doping evaluation are shown in Table 1.

[0162] [Table 1] In Table 1, "round hole type" refers to the multiple openings 223 shown in Figures 10 and 11. "Slit-like" refers to the slit-like openings 223 shown in Figures 12 and 13. "Two-way type" refers to the multiple openings 223 shown in Figures 14 and 15.

[0163] "Material" refers to the material of first blower 213 and second blower 215. "Gas blowing surface" refers to the surface of electrode 1 to which gas is blown. "Power supply roller contact surface" is second surface 221. "Epoxy glass installation" refers to drying units 201A-F equipped with connecting parts 217 made of epoxy glass.

[0164] "Power supply connection method" refers to the electrical configuration in the doping system 11. "-Earth" refers to the first electrical configuration shown in FIG. 2. "+Earth" refers to the second electrical configuration shown in FIG. 3.

[0165] (3) Lithium precipitation evaluation During the pre-doping, Li deposition evaluation was performed. The Li deposition evaluation is an evaluation of the ease of Li deposition on the surface of the power supply roller when the strip-shaped electrode 1 is continuously doped. The criteria for Li deposition evaluation are as follows.

[0166] AA: When electrode 1 was doped at 7500 m or more, Li deposition was observed for the first time.

[0167] A: When electrode 1 with a length of 3000 m or more and less than 7500 m was doped, Li deposition was observed for the first time.

[0168] B: When electrode 1 with a length of 1000 m or more and less than 3000 m was doped, Li deposition was observed for the first time.

[0169] C: Li deposition was observed before doping the 1000 m electrode 1.

[0170] The results of the Li precipitation evaluation are shown in Table 1.

[0171] 2. Example 2 A negative electrode was manufactured basically in the same manner as in Example 1. However, the first blower 213 and the second blower 215 included in the drying units 201A to F each had a plurality of openings 223 as shown in Fig. 14 and Fig. 15. As shown in Fig. 15, when viewed from the axial direction of the first blower 213 and the second blower 215, the angle formed between the direction of the gas 225 blown out from some of the openings 223 and the direction of the gas 225 blown out from the remaining openings 223 was 45 degrees.

[0172] The size and material of the first blower 213 and the second blower 215, the diameter of the openings 223, the pitch of the openings 223, and the number of the openings 223 were the same as in the first embodiment.

[0173] Doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. When 7000 m of electrode 1 was doped, Li deposition was observed on the power supply roller for the first time. During pre-doping, the voltage did not continuously increase. The stable voltage was 3.07 V. The evaluation results are shown in Table 1.

[0174] 3. Example 3 A negative electrode was manufactured basically in the same manner as in Example 1. However, the first blower 213 and the second blower 215 equipped in the drying units 201A to F each had a slit-shaped opening 223 as shown in Figs. 12 and 13. The width of the opening 223 was 1 mm. The length of the opening 223 was 150 mm. The size and material of the first blower 213 and the second blower 215 were the same as in Example 1.

[0175] Doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. Even when 10,000 m of electrode 1 was doped, Li deposition was not observed on the power supply roller. During pre-doping, the voltage did not continuously increase. The stable voltage was 3.04 V. The evaluation results are shown in Table 1.

[0176] 4. Example 4 A negative electrode was produced basically in the same manner as in Example 1. However, the first blower 213 and the second blower 215 were pipes made of polypropylene (PP). In addition, the drying units 201A to F did not include the connection part 217.

[0177] Doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. When 5000 m of electrode 1 was doped, Li deposition was observed on the power supply roller for the first time. During pre-doping, the voltage did not continuously increase. The stable voltage was 3.06 V. The evaluation results are shown in Table 1.

[0178] 5. Example 5 A negative electrode was produced basically in the same manner as in Example 1. However, in addition to the second blower 215, the first blower 213 also blew gas onto the electrode 1. When the electrode 1 reached the power feed roller, in addition to the second surface 221, the first surface 219 was also dry.

[0179] Doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. When 8000 m of electrode 1 was doped, Li deposition was observed on the power supply roller for the first time. During pre-doping, the voltage did not continuously increase. The stable voltage was 3.05 V. The evaluation results are shown in Table 1.

[0180] 6. Example 6 Basically, the negative electrode was manufactured in the same manner as in Example 1. However, the conveying speed of the electrode 1 was set to 4 m / min. The doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. When 2500 m of the electrode 1 was doped, Li deposition was observed on the power supply roller for the first time. During pre-doping, the voltage did not continuously increase. The stable voltage was 3.08 V. The evaluation results are shown in Table 1.

[0181] 7. Example 7 Basically, the negative electrode was manufactured in the same manner as in Example 6. However, the flow rate of nitrogen gas was set to 10 L / min. Doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. When 5000 m of electrode 1 was doped, Li deposition was observed on the power supply roller for the first time. During pre-doping, the voltage did not continuously increase. The stable voltage was 3.05 V. The evaluation results are shown in Table 1.

[0182] 8. Example 8 A negative electrode was manufactured basically in the same manner as in Example 1. However, the electrical configuration of the doping system 11 was the second electrical configuration shown in FIG. 3. The potentials of the first terminal 109A and the first terminal 110A were each −3V. The potentials of the second terminal 109B and the second terminal 110B were each 0V.

[0183] Doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. When 5000 m of electrode 1 was doped, Li deposition was observed on the power supply roller for the first time. During pre-doping, the voltage was a negative value, and the absolute value of the voltage did not continue to increase further. The stable voltage was a negative value, and the absolute value of the stable voltage was less than 3.0 V. The evaluation results are shown in Table 1.

[0184] 9. Comparative Example 1 A negative electrode was produced basically in the same manner as in Example 1. However, the doping system 11 did not include the drying units 201A to F. When the electrode 1 reached the power feed roller, the first surface 219 and the second surface 221 of the electrode 1 were wet with the dope solution.

[0185] Doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. When 500 m of electrode 1 was doped, a large amount of Li was deposited on the power supply roller. During pre-doping, the voltage rose to 3.6 V or more, and pre-doping became impossible. The evaluation results are shown in Table 1.

[0186] 10. Comparative Example 2 The negative electrode was basically manufactured in the same manner as in Comparative Example 1. However, the conveying speed of the electrode 1 was set to 4 m / min. The doping evaluation and Li deposition evaluation were performed in the same manner as in Example 1. When the electrode 1 of 250 m was doped, a large amount of Li was deposited on the power supply roller. During pre-doping, the voltage rose to 3.6 V or more, and pre-doping became impossible. The evaluation results are shown in Table 1. <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms.

[0187] (1) The function of one component in each of the above embodiments may be shared by multiple components, or the functions of multiple components may be performed by one component. Also, part of the configuration of each of the above embodiments may be omitted. Also, at least part of the configuration of each of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[0188] (2) In addition to the doping system described above, the present disclosure can also be realized in various forms, such as a higher-level system that includes the doping system as a component, a program for causing a computer to function as a control device for the doping system, a non-transient physical recording medium such as a semiconductor memory on which this program is recorded, a doping method, etc.

Claims

1. 1. A doping system configured to dope an active material included in an electrode with an alkali metal, comprising: A doping tank configured to accommodate a solution containing ions of an alkali metal and a counter electrode unit; a transport unit configured to transport the electrode along a path passing through the doping tank; a connection unit having a conductive current feed roller in contact with the electrode and configured to electrically connect the electrode and the counter electrode unit; a drying unit configured to blow gas onto the electrode passing through the dope tank and being transported to the power supply roller immediately after passing through the dope tank; A doping system comprising:

2. 1. A method for producing an electrode including an alkali metal-doped active material, comprising: Transporting an electrode including an active material along a path passing through a doping tank that contains a solution including alkali metal ions and a counter electrode unit; drying the electrode that has passed through the dope tank and is being transported to a power supply roller that is one of the power supply rollers that transport the electrode and is located immediately after passing through the dope tank; electrically connecting the electrode and the counter electrode unit after drying; A method for manufacturing an electrode.

3. A method for producing the electrode according to claim 2, comprising the steps of: Drying the electrodes using a blower to blow gas onto the electrodes. A method for manufacturing an electrode.

4. A method for producing an electrode according to claim 3, When electrically connecting the electrode and the counter electrode unit after drying, a conductive power supply roller is used in contact with the electrode, the blower is disposed so as to blow the gas onto a surface of the electrode that is in contact with the current feed roller. A method for manufacturing an electrode.

5. A method for producing the electrode according to claim 3 or 4, comprising the steps of: Drying the electrode using two or more of the blowers arranged so as to sandwich the electrode. A method for manufacturing an electrode.

6. A method for producing the electrode according to any one of claims 3 to 5, comprising the steps of: The blower has a slit-shaped opening for blowing the gas onto the electrode. A method for manufacturing an electrode.

7. A method for producing the electrode according to any one of claims 3 to 5, comprising the steps of: The blower has two or more openings for blowing the gas onto the electrode. A method for manufacturing an electrode.

8. A method for producing the electrode according to any one of claims 3 to 7, comprising the steps of: The gas includes at least one selected from the group consisting of argon gas, helium gas, neon gas, nitrogen gas, carbon dioxide gas, and dehumidified air from which moisture has been removed. A method for manufacturing an electrode.

9. A method for producing the electrode according to any one of claims 3 to 8, comprising the steps of: the material of the blower includes at least one selected from the group consisting of polyolefin resin, polyester resin, polyarylate resin, polyurethane resin, polycarbonate resin, polyamide resin, polyimide resin, polyphenylene sulfide resin, and fluorine-based resin; A method for manufacturing an electrode.

10. A method for producing the electrode according to any one of claims 3 to 8, comprising the steps of: The material of the blower includes at least one selected from the group consisting of a metal, an alloy of two or more metals, an oxide of the metal or the alloy, and a nitride of the metal or the alloy. A method for manufacturing an electrode.

11. 1. A doping system configured to dope an active material included in an electrode with an alkali metal, comprising: A doping tank configured to accommodate a solution containing ions of an alkali metal and a counter electrode unit; a transport unit configured to transport the electrode along a path passing through the doping tank; a connection unit having a conductive current feed roller in contact with the electrode and configured to electrically connect the electrode and the counter electrode unit; a drying unit configured to blow gas onto the electrode passing through the dope tank and being transported to the power supply roller immediately after passing through the dope tank; a power source configured to connect to a main body of the doping system insulated from the dope tank and the power supply roller; Equipped with a potential of a terminal of the power source connected to the power supply roller is lower than a potential of a terminal of the power source connected to the main body; Doping system.

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