Electrode manufacturing method and electrode manufacturing device

Abstract

To provide an electrode manufacturing method and an electrode manufacturing apparatus capable of facilitating drying of an insulating particle-containing slurry applied to portions adjacent to an active material-containing layer on a current collector.SOLUTION: An electrode manufacturing method according to an embodiment includes: forming an active material-containing layer on at least one main surface of a strip-shaped current collector except for both ends in a short side direction of the current collector; spraying mist of slurry containing first insulating particles in a heated state onto adjacent portions to the active material-containing layer on both ends of the current collector in the short-side direction, thereby forming first insulating layers on the adjacent portions, respectively, and applying a second insulating particle-containing slurry onto the active material-containing layer, thereby forming a second insulating layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method and an apparatus for manufacturing an electrode. [Background technology]

[0002] A battery is manufactured by forming an insulating fine particle layer made of an inorganic oxide (titania, alumina, etc.) or an inorganic nitride (aluminum nitride, etc.) on the upper surface of a positive electrode active material layer supported on a positive electrode current collector, and a nonwoven fabric separator on the upper surface of a negative electrode, and then winding these into a coil.

[0003] The insulating fine particle layer is formed, for example, by coating a slurry containing inorganic oxide particles. Since the insulating fine particle layer does not contribute to the charge / discharge reaction, it is desirable that the insulating fine particle layer is a thin film that can maintain insulation. To make the insulating fine particle layer thin, it is desirable to reduce the particle size of the insulating fine particles. In addition, a thinner and more uniform film is more likely to be obtained when the viscosity of the slurry is lower. However, when the slurry viscosity is lowered, the slurry tends to spread to the positive electrode collector protruding from the periphery of the positive electrode active material layer when the slurry is applied to the upper surface of the positive electrode active material layer. Therefore, in order to regulate this spread, it has been considered to form an insulating fine particle layer by coating the slurry on the positive electrode active material layer after forming an insulating fine particle layer as a bank near the boundary with the positive electrode active material layer on the positive electrode current collector.

[0004] The banks are also formed by coating a slurry. Since the banks need to be completed before the insulating fine particle layer is formed on the positive electrode active material layer, the slurry used to form the banks needs to be dried quickly. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-14194 A [Patent Document 2] JP 2016-71956 A [Patent Document 3] JP 2013-196781 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide an electrode manufacturing method and electrode manufacturing apparatus that can promote drying of an insulating particle-containing slurry that is applied to an area adjacent to an active material-containing layer on a current collector. [Means for solving the problem]

[0007] According to an embodiment, an active material-containing layer is formed on at least one main surface of a strip-shaped current collector, except for both ends in a short side direction of the current collector; spraying and applying a mist of the first insulating particle-containing slurry in a heated state to adjacent portions of the active material-containing layer at both ends in a short side direction of the current collector to form a first insulating layer in the adjacent portions; forming a second insulating layer by applying the second insulating particle-containing slurry onto the active material-containing layer; A method for manufacturing an electrode is provided, comprising: Moreover, according to the electrode manufacturing apparatus of the embodiment, the apparatus includes a conveying mechanism, a first unit, a second unit, and a third unit. The conveying mechanism conveys a strip-shaped current collector along a conveying path. The first unit applies an active material-containing slurry to at least one main surface of the current collector at a first position on the conveying path, except for both ends in the short side direction of the current collector, to form an active material-containing layer. The second unit sprays a mist of the first insulating particle-containing slurry in a heated state to apply the slurry to adjacent portions of the current collector at both ends in the short side direction of the current collector at a second position on the conveying path downstream of the first position on the conveying path. The third unit applies a second insulating particle-containing slurry onto the active material-containing layer at a third position on the conveying path downstream of the second position on the conveying path. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an electrode manufacturing apparatus according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a second unit of the electrode manufacturing apparatus shown in FIG. 1. [Diagram 3] FIG. 3 is a schematic plan view of the tip of the nozzle shown in FIG. 2. [Figure 4] FIG. 4 is a plan view of the current collector in a first insulating layer forming step. [Diagram 5] 5 is a cross-sectional view of the current collector shown in FIG. 4 taken along the short side direction (line BB). [Figure 6] FIG. 11 is a plan view of the current collector in the second insulating layer forming step. [Figure 7] FIG. 7 is a cross-sectional view of the current collector shown in FIG. 6 taken along the short side direction (line CC). [Figure 8] FIG. 11 is a plan view showing an example of a cutting method for cutting an electrode. [Figure 9] FIG. 4 is a schematic view showing another example of the second unit of the electrode manufacturing apparatus according to the embodiment. [Figure 10] FIG. 13 is a schematic diagram showing yet another example of an electrode manufacturing apparatus according to an embodiment. [Figure 11] FIG. 2 is a flow diagram showing a battery manufacturing process. [Figure 12] FIG. 2 is a cross-sectional view showing an example of an electrode group using electrodes manufactured by the method or apparatus of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an electrode manufacturing method and an electrode manufacturing apparatus according to an embodiment will be described with reference to the drawings. FIG. 1 shows a schematic diagram of an example of an electrode manufacturing apparatus according to an embodiment. As shown in FIG. 1, the electrode manufacturing apparatus 1 includes a conveying mechanism that conveys a strip-shaped current collector 101 along a conveying path 100a, a first unit, a second unit, and a third unit. The conveying mechanism includes an unwinding roller 100b, a winding roller (not shown), and a plurality of guide rollers (not shown). The strip-shaped current collector 101 is fed from the unwinding roller 100b and guided by the plurality of guide rollers while being wound up by the winding roller, and is conveyed in the order of the first unit, the second unit, and the third unit in a roll-to-roll manner. The electrodes are manufactured in a dry air atmosphere maintained at room temperature, for example.

[0010] The first unit applies active material-containing slurry S to at least one main surface of the current collector 101 at the first position 2 of the transport path 100a, except for both ends of the current collector 101 in the short side direction. 1 The first unit includes, for example, a coater 3. The coater 3 coats one main surface of the current collector 101, except for both ends in the short side direction, with the active material-containing slurry S at a first position 2 on the transport path 100a. 1 The coater 3 may be, for example, a slit coater. A dryer 8 and a press are provided in this order downstream of the first position 2 of the transport path 100a. The dryer 8 dries (e.g., pre-dries) the active material-containing layer 102 applied on the current collector 101 transported along the transport path 100a. The dryer 8 is, for example, an infrared (IR) lamp, a hot air dryer, a stage heating device, or a heat roller. The press applies a press (e.g., a correction press) to the active material-containing layer 102 on the current collector 101 transported along the transport path 100a. The press includes press rollers 9a and 9b. The press rollers 9a and 9b face each other with the current collector 101 and the active material-containing layer 102 on the transport path 100a sandwiched therebetween. The press rollers 9a and 9b are arranged with their respective rotation axes parallel to a direction intersecting the flow direction of the transport path 100a. As press roller 9a rotates counterclockwise and press roller 9b rotates clockwise, press rollers 9a and 9b rotate in opposite directions to each other, and active material-containing layer 102 on current collector 101 on transport path 100a passes between press rollers 9a and 9b in this rotating state, thereby pressing active material-containing layer 102, and the pressed current collector 101 and active material-containing layer 102 are transported to second position 4.

[0011] The second unit 5 is provided downstream of the first position 2, the dryer 8, and the press rollers 9a and 9b on the transport path 100a. The second unit 5 sprays a mist S of the first insulating particle-containing slurry onto the adjacent portions of the active material-containing layer 102 on both ends in the short side direction of one main surface of the current collector 101 at the second position 4 on the transport path 100a. 2The second unit 5 is sprayed and applied in a heated state. A schematic diagram of the second unit 5 is shown in FIG. 2. As shown in FIG. 2, the second unit 5 includes, for example, a nozzle 10, a mist supply unit 11, and a gas supply unit 12. The nozzle 10 includes a first flow path 13 having a tapered tip, an inlet 14 which is an inlet of the first flow path 13, a first jet 15 which is an outlet of the first flow path 13, a second flow path 16 having a needle-shaped tip, a second jet 17 which is an outlet of the second flow path 16, and a heater 18. FIG. 3 shows a schematic diagram of the tip of the nozzle 10 as viewed from the direction indicated by A in FIG. 2. As shown in FIG. 3, the first jet 15 is located near the center of the tip of the nozzle 10. The second jet 17 is an opening formed concentrically with the first jet (jet) 15. The second jet 17 jets gas that guides the mist jetted from the first jet 15. The needle-shaped tip of the second flow path 16 is inclined approximately parallel to a tapered surface that defines the tip of the first flow path 13. The heater 18 is provided in the nozzle 10 between a wall that defines the first flow path 13 and a wall that defines the second flow path 16. The heater 18 is adjacent to the wall that defines the first flow path 13 in the nozzle 10, and heats the fluid (e.g., mist, liquid) passing through the first flow path 13. The heater 18 is, for example, an electric heater.

[0012] The mist supply unit 11 includes, for example, a mist generator 20, a drive unit 21, and an adjustment unit (not shown). The mist generator 20 supplies the first insulating particle-containing slurry S 4 The mist generator 20 has a cavity into which the slurry S is supplied. The cavity is connected to the inlet 14 of the first flow path 13. 4 From Mist S 2 The driving unit 21 is provided in the first flow path 13, and when driven, the mist generator 20 generates a mist S through the first flow path 13. 2 The mist S supplied to the first nozzle 15 in the nozzle 10. In one example, the driving unit 21 is a pump. 2 In one example, the adjustment unit adjusts the flow rate and pressure of the mist S 2 The device is equipped with a control valve capable of controlling the flow rate, pressure, etc.

[0013] The gas supply unit 12 includes, for example, a drive unit 22 and an adjustment unit (not shown). The drive unit 22 is provided in the second flow path 16. Gas is supplied to the second flow path 16 from the gas storage unit. The drive unit 22 drives the gas to be supplied to the second nozzle 17 of the nozzle 10 through the second flow path 16. In one example, the drive unit 22 is a pump. The adjustment unit adjusts the flow rate and pressure of the gas supplied to the second flow path 16. In one example, the adjustment unit includes a control valve capable of controlling the flow rate and pressure of the gas. For example, air (dry air) or nitrogen is used as the gas. The gas can function as a sheath gas or a carrier gas.

[0014] The operation of the second unit 5 will be described. The slurry S supplied into the mist generator 20 4 Mist S generated from 2 The mist S flows into the first flow passage 13 of the nozzle 10 from the inlet 14 along the direction of the arrow shown in FIG. 2 After being heated by the heater 18, the sheath gas moves along the direction of the arrow shown in FIG. 2 and is sprayed from the first nozzle 15 onto the current collector 101. Meanwhile, the sheath gas supplied to the second flow path 16 moves along the direction of the arrow shown in FIG. 2 and is sprayed from the second nozzle 17 to form a mist S. 2 As a result, the sheath gas acts as a guide to the mist S. 2 As a result, the mist S reaches the target position on the current collector 101. 2 It is easy to spray Mist S. 2 By adjusting the flow rate, pressure, etc. of the mist S, the mist S can be directed to the target position on the current collector 101 without being guided by the sheath gas. 2 In this case, the guide by the sheath gas can be omitted.

[0015] The third unit deposits a second insulating particle-containing slurry S on the upper surface of the active material-containing layer 102 at a third position 6 on the transport path 100a downstream of the second position 4 on the transport path 100a. 3The third unit includes, for example, a coater 7. The coater 7 coats the second insulating particle-containing slurry S on the upper surface of the active material-containing layer 102 on the current collector 101 at the third position 6 on the transport path 100a. 3 The coater 7 is, for example, a slit coater or a spray.

[0016] A method for manufacturing an electrode using the manufacturing apparatus described above will be described.

[0017] The electrode is manufactured, for example, in a dry air atmosphere set at room temperature. A strip-shaped current collector 101 is transported along a transport path 100a. At a first position 2 on the transport path 100a, active material-containing slurry S is applied to one main surface of the current collector 101 except for both ends in the short side direction of the current collector 101. 1 is applied to form an active material-containing layer 102. The ends in the short side direction of the current collector 101 are edges along the long side direction of the current collector 101, and are portions that can function as current collecting tabs or leads of the electrode.

[0018] Next, the current collector 101 coated with the active material-containing layer 102 is transported to the dryer 8 along the transport path 100a. The active material-containing layer 102 is semi-dried by the dryer 8. Semi-drying refers to a state in which the solvent remains in the active material-containing layer 102. The surface of the active material-containing layer 102 has irregularities reflecting the shape of the positive electrode active material particles. The active material-containing layer 102 is dried only in a semi-dry state so that the surface irregularities of the active material-containing layer 102 can be reduced and a smooth surface can be easily obtained by pressing in the next step. In the next step, the active material-containing layer 102 on the current collector 101 transported along the transport path 100a is sandwiched between press rollers 9a and 9b, and the active material-containing layer 102 is pressed (correction pressing). This pressing can reduce the surface irregularities of the active material-containing layer 102 and increase the surface smoothness. As a result, even if the thickness of the second insulating layer 104 covering the surface of the active material-containing layer 102 is reduced, there is no risk of the unevenness on the surface of the active material-containing layer 102 breaking through the second insulating layer, so that the thin second insulating layer 104 can maintain its insulating properties.

[0019] In addition, instead of providing a dryer for drying the active material-containing layer on the current collector located between the first position and the second position of the transport path and a press for pressing the active material-containing layer dried by the dryer, a heat press may be used, and the dryer may not be used. In addition, if the surface smoothness of the active material-containing layer 102 after coating is sufficiently high, the above-mentioned drying step and pressing step can be omitted.

[0020] The current collector 101 after coating, drying and pressing of the active material-containing layer 102 is transported along the transport path 100a to the next step (second unit 5). The next step, a first insulating layer forming step, will be described with reference to Fig. 4. Fig. 4 is a plan view of the current collector in the first insulating layer forming step.

[0021] Both ends 101a in the short side direction on one main surface of the strip-shaped current collector 101 are portions where no active material-containing layer is formed. An active material-containing layer 102 is formed on one main surface of the strip-shaped current collector 101 except for the both ends 101a. The short side direction of the strip-shaped current collector 101 is a direction intersecting with the long side direction 105 of the strip-shaped current collector 101. A mist S of a first insulating particle-containing slurry is applied at a second position 4 of the transport path 100a to the adjacent portions of the active material-containing layer 102 at both ends 101a in the short side direction of one main surface of the current collector 101 transported along the transport path 100a. 2 The mist S generated in the mist generator 20 is applied. 2 The mist S passes through the inlet 14 and is supplied into the first flow path 13 along the direction of the arrow shown in FIG. 2, and is then heated by the heater 18. 2 2 and is sprayed from the first nozzle 15 onto the current collector 101 on the transport path 100a, while the sheath gas sprayed from the second nozzle 17 is mist S 2 To be a guide for Mist S 2 As a result, the mist S heated at the target position on the current collector is 2 It is possible to spray Mist S 2 Since it is heated, Mist S 2 When applied, Mist S dissolves in water within a short time. 2The solvent evaporates from the solvent. As a result, it is possible to form first insulating layer 103 in a short time in the portion adjacent to active material-containing layer 102 at both ends 101a in the short side direction of one main surface of current collector 101. Then, the next step of forming a second insulating layer can be started.

[0022] 5, a first insulating layer 103 is formed on each of the portions adjacent to the long sides of the active material-containing layer 102 on the current collector 101. The current collector transported along the transport path 100a has a second insulating particle-containing slurry S 3 The second insulating particle-containing slurry S 3 The current flows along the surface of the active material-containing layer 102 onto the current collector 101, but is restricted by the first insulating layer 103. As a result, as shown in Figures 6 and 7, the second insulating layer 104 is formed on the upper surface of the active material-containing layer 102 and the four side surfaces connected thereto, and a structure is obtained in which both edges in the long side direction of the second insulating layer 104 are sandwiched between the first insulating layer 103. 1 is the thickness T of the active material-containing layer 2 It is desirable that the thickness of the first insulating layer is equal to or larger than the thickness T of the first insulating layer. This ensures a sufficient function as a bank for regulating the flow of the second insulating particle-containing slurry. To make the first insulating layer thicker, it is desirable to increase the viscosity of the first insulating particle-containing slurry. Here, the thickness T of the first insulating layer is 1 is the distance between the main surface of the current collector and the tip surface of the first insulating layer. 2 is the distance between the main surface of the current collector and the main surface of the active material-containing layer. Also, the thickness T 3 is the active material containing layer T 2 It is desirable that the thickness of the electrode be thinner than the thickness of the electrode. This allows the electrode reaction to occur smoothly. 1 , thickness T 2 , thickness T 3are measured by observation with a scanning electron microscope (SEM). The thickness of each of the first insulating layer and the second insulating layer can be set within a desired range by adjusting the concentration of the insulating particle-containing slurry. A lower slurry viscosity allows the insulating layer to be thinner, and a higher slurry viscosity allows the insulating layer to be thicker. Note that the second insulating particle-containing slurry S 3 After application of the coating agent, a drying step is carried out as necessary.

[0023] When forming the active material-containing layer 102 on both sides of the current collector, the second insulating particle-containing slurry S is applied to one main surface of the current collector. 3 After coating, the substrate is dried as necessary and either wound up once on a winding machine or turned over without winding on a winding machine, and an active material-containing layer, a first insulating layer, and a second insulating layer are formed on the uncoated surface.

[0024] The electrode obtained as described above is subjected to a cutting process as necessary, and then to a pressing process for density adjustment, etc. An active material-containing layer is not formed on both ends of the short side direction of the current collector. This part without the active material-containing layer can function as a current collecting tab. The current collecting tab may be present at both ends of the electrode, or only at one end. For example, as shown in FIG. 8, by cutting along the long side direction of the electrode (two-dot chain line L), an electrode having a current collecting tab only at one end is obtained.

[0025] In the above example, the nozzle of the second unit is provided with a heater to heat the mist of the first insulating particle-containing slurry, but the heating method is not limited to the method of heating the mist of the first insulating particle-containing slurry and then ejecting the mist from the first ejection port. For example, the mist ejected from the first ejection port may be heated. Specifically, a method of heating a container storing the sheath gas from the outside and pumping it, or a method of using a hot air machine such as a dryer, etc., may be used. An example of a method of heating a container storing the sheath gas and pumping it will be described with reference to FIG. 9. In FIG. 9, the same members as those described in FIG. 2 are denoted with the same reference numerals and the description will be omitted. The nozzle 10 has a structure similar to that described in FIG. 2, except that a heater is not provided.

[0026] The gas supply unit 12 includes, for example, a heater 30 as a first heater, a cavity 31, a drive unit 22, and an adjustment unit (not shown). The heater 30 is a first heater that heats the gas supplied to the second nozzle 17. The heater 30 heats the gas accommodated in the cavity 31 therein to a target temperature. The cavity 31 of the heater 30 communicates with the second flow path 16. The drive unit 22 is provided in the second flow path 16, and is driven to move the gas in the cavity 31 of the heater 30 to the second flow path 16 along the arrow direction shown in FIG. 9 and supply it to the second nozzle 17. In one example, the drive unit 22 is a pump. The adjustment unit adjusts the flow rate, pressure, etc. of the gas supplied to the second flow path 16. In one example, the adjustment unit includes a control valve that can control the flow rate, pressure, etc. of the gas. Examples of the gas are as described above.

[0027] According to the gas supply unit 12, the gas heated by the heater 30 moves through the second flow path 16 along the direction of the arrow shown in FIG. 9 and is supplied to the second nozzle 17. The sheath gas is ejected from the second nozzle 17, and the sheath gas is turned into mist S. 2 As a result, the sheath gas acts as a guide and the mist S 2 The diffusion of mist S is suppressed and the sheath gas 2 As a result, the heated mist S 2 is sprayed onto the current collector 101 at a target position. When a hot air machine such as a dryer is used instead of the heater 30, hot air is supplied to the second flow passage 16 in FIG. 9 from the blower port of the dryer, and the hot air is ejected from the second ejection port 17 to be used as the sheath gas.

[0028] The temperature of the mist of the first insulating particle-containing slurry is preferably in the range of 40°C or more and 80°C or less. By setting the temperature at 40°C or more, the volatilization of the solvent in the slurry applied to the current collector can be promoted. Furthermore, by setting the temperature at 80°C or less, the temperature can be easily controlled and clogging of the nozzle hole can be prevented even when a highly volatile solvent is used as the solvent in the slurry. To set the temperature of the mist in the above range, for example, the temperature of the heater in the nozzle of the second unit or the temperature of the first heater of the second unit can be set to 40°C or more and 80°C or less. Both the heater and the first heater may be used.

[0029] In addition to heating the mist of the first insulating particle-containing slurry, it is desirable to heat the current collector. This can promote drying of the applied mist. As an example of a method for heating the current collector, FIG. 10 shows an example using a device equipped with a second heater that heats the current collector at a second position on the transport path. In FIG. 10, the same members as those described in FIG. 1 are given the same reference numerals and the description thereof is omitted.

[0030] The electrode manufacturing apparatus further includes a local heating support 40 as a second heater. The local heating support 40 is provided at a position facing the nozzle 10 with the current collector 101 located at the second position 4 of the transport path 100a in between. The heating support 40 supports and heats the surface of the current collector 101 opposite to the surface to be coated. The local heating support 40 is, for example, an electric heater or an IH (Induction Heating) heater. By heating the current collector from the surface opposite to the surface to be coated, the drying of the applied mist can be promoted. The heating of the current collector does not have to be the entire main surface. For example, heating may be concentrated on both ends of the current collector in the short side direction. The temperature at which the current collector is heated is preferably in the range of 40°C to 80°C.

[0031] The application of the mist of the first insulating particle-containing slurry can be performed by the aerosol jet method, the inkjet method, or the spray method. The size of the mist (droplets) is larger in the spray method than in the other two methods. The aerosol jet method has a wider range of viscosity of the slurry that can be discharged than the other two methods. For example, the range of the slurry viscosity that can be discharged by the inkjet method is about 10 to 40 mPa·s, for example. The range of the slurry viscosity that can be discharged by the aerosol jet method is about 100 to 1000 mPa, for example. The slurry viscosity can be adjusted by the solid content concentration. By applying the aerosol jet method to the method or apparatus of the embodiment, a first insulating layer having a thick film thickness can be formed in a short time.

[0032] The materials constituting the electrodes will be described below. Active material-containing slurry S 1 is prepared, for example, by dispersing active material particles and a binder in a solvent. The active material particles may be either positive electrode active material particles or negative electrode active material particles. The positive electrode active material may be, for example, a lithium transition metal composite oxide. An example of the lithium transition metal composite oxide is LiCoO 2 , LiNi 1-x Co x O 2 (0 <x<0.3)、LiMn x Ni y Co z O 2 (0 <x<0.5、0<y<0.5、0≦z<0.5)、LiMn 2-x M x O 4 (M is at least one element selected from the group consisting of Mg, Co, Al, and Ni; O <x<0.2)、LiMPO 4(M is at least one element selected from the group consisting of Fe, Co, and Ni). Carbon materials such as graphite, tin-silicon alloy materials, and the like can be used as the negative electrode active material, but it is preferable to use lithium titanate. Titanium oxides containing other metals such as (niobium) Nb or lithium titanate can also be used as the negative electrode active material. Examples of lithium titanate include Li 4+x Ti 5 O 12 (0≦x≦3) and Li with ramsdellite structure 2+y Ti 3 O 7 (0≦y≦3).

[0033] Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene butadiene rubber, and mixtures thereof. If necessary, a conductive agent may be included. Examples of the conductive agent include acetylene black, carbon black, graphite, and mixtures thereof. As the solvent, an organic solvent such as n-methylpyrrolidone (NMP) can be used.

[0034] The current collector may be a conductive sheet. Examples of the conductive sheet include foils made of conductive materials. Examples of the conductive materials include aluminum and aluminum alloys. The thickness of the current collector may be 5 μm or more and 40 μm or less.

[0035] The first insulating particle-containing slurry contains, for example, insulating particles, a binder, and a solvent. The insulating particles are, for example, inorganic oxide particles or inorganic nitride particles. Examples of inorganic oxides include TiO 2 Titanium oxides such as Al 2 O 3Examples of the inorganic nitride include aluminum oxides such as AlN, and examples of the inorganic nitride include aluminum nitrides such as AlN. The average particle size of the insulating particles can be smaller than the average particle size of the active material particles. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene butadiene rubber, or a mixture thereof. Examples of the solvent include an organic solvent such as n-methylpyrrolidone (NMP).

[0036] The second insulating particle-containing slurry contains, for example, insulating particles, a binder, and a solvent. The insulating particles, binder, and solvent may be the same as those described for the first insulating particle-containing slurry. The average particle size of the insulating particles is preferably smaller than the average particle size of the active material particles. This allows the thickness of the second insulating layer to be thinner than the thickness of the active material-containing layer. The compositions of the first insulating particle-containing slurry and the second insulating particle-containing slurry may be the same or different.

[0037] According to the method of the embodiment described above, the method includes forming an active material-containing layer on at least one main surface of a strip-shaped current collector except for both ends in the short side direction, spraying and applying a mist of a first insulating particle-containing slurry in a heated state to the adjacent portion of the active material-containing layer at both ends in the short side direction of the current collector to form a first insulating layer on the adjacent portion, and applying a second insulating particle-containing slurry on the active material-containing layer to form a second insulating layer. According to this method, the mist applied to the adjacent portion can be dried in a short time to form the first insulating layer. As a result, mass productivity can be improved. In addition, stress during drying can be relieved to prevent the first insulating layer from cracking. In the next step, when the second insulating particle-containing slurry is applied to the upper surface of the active material-containing layer, the second insulating particle-containing slurry tries to flow onto the current collector along the surface of the active material-containing layer, but is blocked by the first insulating layer. As a result, a second insulating layer is formed on the upper surface of the active material-containing layer, and an electrode having a structure in which both ends of the second insulating layer in the short side direction are sandwiched between the first insulating layers can be obtained. Therefore, even if the viscosity of the second insulating particle-containing slurry is reduced, uneven coating due to dripping is unlikely to occur, and the surface of the active material-containing layer can be uniformly covered. In addition, since both ends of the second insulating layer in the short side direction are sandwiched between the first insulating layers, peeling of the second insulating layer from the active material-containing layer can be suppressed. Therefore, insulation can be maintained with a thin and uniform insulating layer.

[0038] The electrode manufacturing apparatus of the embodiment includes a conveying mechanism for conveying a strip-shaped current collector along a conveying path, a first unit for applying an active material-containing slurry to at least one main surface of the current collector at a first position on the conveying path, except for both ends in the short side direction, to form an active material-containing layer, a second unit for spraying a mist of a first insulating particle-containing slurry in a heated state to adjacent portions of the active material-containing layer at both ends in the short side direction of the current collector at a second position on the conveying path downstream of the first position on the conveying path, and a third unit for applying a second insulating particle-containing slurry on the active material-containing layer at a third position on the conveying path downstream of the second position on the conveying path. According to this electrode manufacturing apparatus, the mist applied to the adjacent portions can be dried in a short time to form a first insulating layer. In addition, stress during drying can be alleviated to prevent the first insulating layer from cracking. In the third unit, the second insulating particle-containing slurry is applied to the upper surface of the active material-containing layer, and the flow of the second insulating particle-containing slurry is regulated by the first insulating layer. As a result, the second insulating layer is formed on the upper surface of the active material-containing layer, and an electrode having a structure in which both ends of the second insulating layer in the short side direction are sandwiched between the first insulating layer can be obtained. Therefore, even if the viscosity of the second insulating particle-containing slurry is reduced, uneven coating due to dripping is unlikely to occur, and the surface of the active material-containing layer can be uniformly covered. In addition, since both ends of the second insulating layer in the short side direction are sandwiched between the first insulating layer, it is possible to suppress the second insulating layer from peeling off from the active material-containing layer. Therefore, the insulation properties can be maintained with a thin and uniform insulating layer.

[0039] FIG. 11 shows an example of a method for manufacturing a secondary battery using an electrode manufactured by the method or device of the embodiment. According to the embodiment, slurry preparation (insulating inorganic coating liquid preparation 201, positive electrode coating liquid dispersion 202, negative electrode coating liquid dispersion 203), coating 204, slitting (cutting) 205, and roll press 206 are performed. Thereafter, if necessary, a porous layer is formed on the surface of the positive electrode or negative electrode by electrospinning (207). Next, the positive electrode and the negative electrode are wound or stacked with at least an insulating layer interposed therebetween to prepare an electrode group (208). The electrode group is stored in an outer container and dried (209), and then an electrolyte is poured (210). After sealing the outer container, aging treatment and the like are performed, and then a degassing process is performed (211). Then, charging and discharging are performed (212), a pre-shipment inspection (213) is performed, and the secondary battery is shipped (214).

[0040] FIG. 12 shows an example of an electrode group using electrodes manufactured by the method or device of the embodiment. The positive electrode 106 is manufactured by the method or device of the embodiment. The current collector 101a on which the positive electrode active material-containing layer is not formed functions as a positive electrode tab. The negative electrode 107 is manufactured by a method other than the method of the embodiment. The negative electrode 107 includes a band-shaped negative electrode current collector 108, a negative electrode tab 108a protruding from one long side of the negative electrode current collector 108, a negative electrode active material-containing layer 109 formed on both main surfaces of the negative electrode current collector 108, and a porous layer 110 made of organic fibers that covers both main surfaces of the negative electrode active material-containing layer 109 and four side surfaces intersecting both main surfaces. The positive electrode 106 and the negative electrode 107 are laminated with the second insulating layer 104 and the porous layer 110 interposed therebetween. The direction in which the positive electrode tab 101a extends is opposite to the direction in which the negative electrode tab 108a extends.

[0041] An electrode group using electrodes manufactured by the method or apparatus of the embodiment can maintain reliability for a long period of time because cracks or breaks do not occur in first insulating layer 103 and second insulating layer 104.

[0042] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. As another example, an ultraviolet curing resin is added to the first insulating particle-containing slurry, and the mist is sprayed and applied in a heated state, and then the applied mist is cured in a short time by irradiating ultraviolet light to form a first insulating layer. The method of heating and applying the mist may be any of the above-mentioned embodiments. In addition, the electrode manufacturing apparatus of the embodiment may include an ultraviolet lamp that irradiates ultraviolet light to the first insulating particle-containing slurry on the current collector at the second position of the transport path. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and modifications are included within the scope and spirit of the invention, and are included in the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0043] Reference Signs List 1...electrode manufacturing apparatus, 2...first position, 3...applicator, 4...second position, 5...second unit, 6...third position, 7...applicator, 8...dryer, 9a...press roller, 9b...press roller, 10...nozzle, 11...mist supply section, 12...gas supply section, 13...first flow path, 14...inlet, 15...first outlet, 16...second flow path, 17...second outlet, 18...heater, 20...mist generator, 21...driving section, 22...driving section, 30...warmer, 31...cavity, 40...heating support, 100a...transport path, 100b...roller, 101...current collector, 101a...both ends , 102... active material-containing layer, 103... first insulating layer, 104... second insulating layer, 105... long side direction, 106... positive electrode, 107... negative electrode, 108... negative electrode current collector, 108a... negative electrode tab, 109... negative electrode active material-containing layer, 110... porous layer, 201... production of insulating inorganic coating liquid, 202... dispersion of positive electrode coating liquid, 203... dispersion of negative electrode coating liquid, 204... coating, 205... slitting (cutting), 206... roll press, 207... electrospinning, 208... winding, 209... drying, 210... injection, 211... degassing, 212... charging and discharging, 213... pre-shipment inspection, 214... shipment, S 1 …Active material-containing slurry, S 2... Mist, S 3 …Second insulating particle-containing slurry, S 4 …first insulating particle-containing slurry, T 1 …thickness of the first insulating layer, T 2 ...the thickness of the active material-containing layer.

Claims

1. forming an active material-containing layer on at least one main surface of a strip-shaped current collector, except for both ends in a short side direction of the current collector; spraying and applying a mist of a first insulating particle-containing slurry in a heated state onto adjacent portions of the active material-containing layer at both ends of the current collector in the short side direction to form a first insulating layer in the adjacent portions; forming a second insulating layer by applying a second insulating particle-containing slurry onto the active material-containing layer; A method for manufacturing an electrode comprising the steps of:

2. The method for manufacturing an electrode according to claim 1 , wherein the mist of the first insulating particle-containing slurry is heated to 40° C. or more and 80° C. or less.

3. 3. The method for manufacturing an electrode according to claim 1, wherein the coating of the first insulating particle-containing slurry is performed by heating the first insulating particle-containing slurry and spraying the heated mist of the first insulating particle-containing slurry onto the adjacent portion of the current collector.

4. The method for manufacturing an electrode according to claim 1 , wherein the first insulating particle-containing slurry is applied to the current collector while heating the current collector.

5. 5. The method for manufacturing an electrode according to claim 1, wherein the first insulating particle-containing slurry contains an ultraviolet curing resin, and a mist of the first insulating particle-containing slurry is heated and sprayed onto adjacent portions of the current collector at both ends in the short side direction, and then the applied first insulating particle-containing slurry is irradiated with ultraviolet light to form a first insulating layer in the adjacent portions.

6. 6. The method for producing an electrode according to claim 1, wherein the active material-containing layer is formed by applying an active material-containing slurry to at least one main surface of the current collector except for both end portions in the short side direction of the current collector, drying the slurry, and pressing the slurry.

7. a conveying mechanism that conveys the strip-shaped current collector along a conveying path; a first unit that applies an active material-containing slurry to at least one main surface of the current collector at a first position on the transport path, excluding both end portions in a short side direction of the current collector, to form an active material-containing layer; a second unit that sprays a mist of a first insulating particle-containing slurry in a heated state onto adjacent portions of the active material-containing layer at both ends of the current collector in the short side direction at a second position of the transport path downstream of the first position of the transport path, and applies the mist to the active material-containing layer; a third unit that applies a second insulating particle-containing slurry onto the active material-containing layer at a third position of the transport path downstream of the second position of the transport path; and An electrode manufacturing apparatus comprising:

8. 8. The electrode manufacturing apparatus according to claim 7, wherein the second unit comprises: a flow path having an outlet for ejecting a mist of the first insulating particle-containing slurry; and a heater for heating the flow path.

9. 8. The electrode manufacturing apparatus of claim 7, wherein the second unit comprises a first nozzle that sprays a mist of the first insulating particle-containing slurry, a second nozzle that is provided around the first nozzle and sprays a gas that guides the mist sprayed from the first nozzle, and a first heater that heats the gas supplied to the second nozzle.

10. The electrode manufacturing apparatus according to claim 7 , further comprising a second heater configured to heat the current collector at the second position on the transport path.

11. 8. The electrode manufacturing apparatus according to claim 7, further comprising: a dryer that dries the active material-containing layer on the current collector located between the first position and the second position of the transport path; and a press that presses the active material-containing layer dried by the dryer.

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