JP6424616B2 - Electrode manufacturing equipment - Google Patents

Description

The present invention has an active material layer of at least one surface a porous current collector and the surface of the active material layer is relates to the production equipment of covered with a protective film electrode.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug-in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion secondary battery as a power storage device for storing power supplied to a motor serving as a prime mover. The electrode of the secondary battery has a structure in which an active material layer containing an active material and a current collector (for example, a metal foil) are integrally laminated. In addition, it has been proposed to coat a protective layer containing particles of an inorganic material (for example, ceramic material) on the surface of the active material layer in such an electrode.

  In forming the protective layer, a protective layer-forming material including particles of an inorganic material, a binder, and a solvent is applied so as to cover the surface of the active material layer integral with the current collector. Thereafter, the protective layer-forming material is dried to form a protective layer comprising particles of the inorganic material and a binder.

  By the way, the active material layer has a structure in which active material particles are mutually fixed by a binder made of a resin material, and has a porous shape provided with a large number of voids between the active material particles. Therefore, as shown in FIG. 5, when the protective layer forming material 101 is applied to the surface of the active material layer 102 integral with the current collector 103, part of the protective layer forming material 101 is inside the active material layer 102. Instead, the gas in the active material layer 102 moves as air bubbles to the surface side of the protective layer forming material 101. If the protective layer forming material 101 is dried in this state, the protective layer may become thin at the portion where the air bubbles are mixed, or the internal air bubbles may be ejected during the drying process, so that a part of the protective layer may not be formed. . Partially thinning the protective layer is not preferable because it causes deterioration of the protective function.

  Therefore, conventionally, there has been proposed a manufacturing apparatus in which a liquid substance is applied to the surface of the active material layer integral with the current collector and the gas inside the active material layer is replaced with the liquid substance before the formation of the protective layer. (See Patent Document 1). Thereby, since the gas inside the active material layer can be removed in advance, it is possible to suppress the mixing of air bubbles between the current collector and the protective layer forming material when forming the protective layer thereafter.

JP, 2009-277598, A

  Since the manufacturing apparatus described above simply infuses the liquid substance into the inside of the porous active material layer, there is a possibility that gas may remain between the current collector and the liquid substance without the liquid substance soaking well. . In this case, when the protective layer forming material is applied to the surface of the active material layer coated with the liquid substance, air bubbles are mixed between the current collector and the protective layer forming material.

  For example, in Patent Document 1, as in the case of applying the protective layer-forming material, a liquid substance is applied by a roll as a pretreatment, but at this time, a part of air is trapped and becomes air bubbles. Sufficient time is required to move the bubbles and discharge them to the outside. If the time from the application of the liquid substance to the application of the protective layer-forming material is increased, the discharged air bubbles increase, but there are restrictions on the facility such as an increase in size of the apparatus.

The present invention has been made in view of such circumstances, and its object is production equipment of electrodes that can suppress mixing of bubbles into between the formation of the protective layer and the current collector and the protective layer forming material To provide.

  An apparatus for producing an electrode for achieving the above object is an apparatus for producing an electrode having a porous active material layer on at least one side of a current collector and the surface of the active material layer covered with a protective layer. A first application unit for applying a protective layer-forming material including a first particle made of an inorganic material, a binder, and a solvent on the surface of the active material layer integral with the current collector; And a solvent, which is a particle made of an inorganic material and smaller than the first particle, on the surface of the active material layer integral with the current collector in a step prior to the application of the protective layer-forming material. And a voltage application unit for applying a voltage between the second application unit and the current collector.

  According to the above manufacturing apparatus, when applying the pretreatment material from the second application unit to the surface of the active material layer integrated with the current collector, the pretreatment material is between the current collector and the second application unit. It can be in an interposed state and in a state where a voltage is applied. Therefore, the second particles in the pretreatment material can be attracted to the current collector by the electrostatic adsorption action by the applied voltage. Thereby, since the pretreatment material containing the second particles can be forcibly pushed into the gap of the active material in the active material layer, the gap can be filled with the pretreatment material and the gas can be pushed out from the gap. In the above manufacturing apparatus, since the second particles contained in the pretreatment material are small and easily enter the gaps between the active materials, the gaps can be suitably filled.

  Then, according to the above-mentioned manufacturing apparatus, the protective layer forming material can be applied to the surface of the active material layer in a state in which the gaps between the active materials are filled with the pretreatment material. It is possible to preferably suppress the mixing of air bubbles in between. In the above-described manufacturing apparatus, the first particles contained in the protective layer-forming material are relatively large and difficult to intrude into the gaps between the active materials, and therefore, remain on the surface of the active material layer to form the protective layer.

In the said manufacturing apparatus, it is preferable that the said 2nd particle | grain consists of metal oxides.
Usually, particles of metal oxide (for example, alumina) are formed in a near spherical shape. Therefore, by using the metal oxide particles as the second particles, the second particles are less likely to be caught in the gaps of the active material, and easily enter the gaps. According to the above-described manufacturing apparatus in which such metal oxide particles are used as the second particles, the gaps of the active material can be suitably filled with the second particles.

  In the above manufacturing apparatus, the second application unit has a die head for discharging the pretreatment material, and the manufacturing apparatus has a transport roller for transporting an electrode material including the current collector and the active material layer, The voltage application unit preferably applies a voltage between the die head and the transport roller.

According to the above-described manufacturing apparatus, a voltage can be applied between the transport roller with which the electrode material contacts and the die head of the second application unit.
In the above manufacturing apparatus, the pretreatment material preferably contains a binder.

  According to the above-described manufacturing apparatus, the binder in the pretreatment material can bond the second particles that have penetrated into the gaps of the active material layer to the active material, or bond the second particles to each other, and the active material layer Can increase the strength of

In the above manufacturing apparatus, the electrode can be used as an electrode of a secondary battery .

  According to the present invention, it is possible to suppress the entry of air bubbles between the current collector and the protective layer forming material when forming the protective layer.

The perspective view of the electrode manufactured by the manufacturing apparatus of one embodiment. The figure which shows schematic structure of the same manufacturing apparatus. (A) And (b) is a schematic diagram which shows the permeation aspect to the active material layer of a pretreatment material. The schematic diagram which shows the application | coating aspect of protective layer formation material. The schematic diagram which shows the cross-section of the electrode in the formation process of a protective layer.

Hereinafter, an embodiment in which an electrode manufacturing apparatus and an electrode are embodied will be described according to FIGS. 1 to 4.
Although not shown, the secondary battery to which the electrode of the present embodiment is applied is a rectangular battery having a square external appearance, and is a lithium ion battery. An electrode assembly is provided in the case of the secondary battery, and the electrode assembly has a plurality of positive electrodes and a plurality of negative electrodes. The electrode assembly is configured by alternately laminating a positive electrode and a negative electrode in a state of being insulated by a resin separator.

Hereinafter, the structure of the electrode of the secondary battery will be described.
As shown in FIG. 1, the electrode 10 is formed of a rectangular metal foil 11 as a current collector, a rectangular active material layer 12 provided on both sides of the metal foil 11, and the entire surface of the active material layer 12. And a protective layer 13 (shown by dot hatching in FIG. 1) covering the above. The protective layer 13 has an insulating function to suppress a short circuit between the positive electrode and the negative electrode 10 and has heat resistance superior to that of a resin-made separator. The electrode 10 has an uncoated portion 12 a where the active material layer 12 is not provided along one side of the electrode 10 and the metal foil 11 is exposed. And the current collection tab 14 is provided in a part of uncoated part 12a in the state which protrudes.

  The active material layer 12 is formed by fixing the active materials (specifically, the particles [having a particle diameter of about 10 μm]) to each other by a binder, and a large number of voids serving as electrolyte and ion passages between the active materials. Is porous. Moreover, the protective layer 13 is comprised by the particle | grains and binder which consist of inorganic materials (this embodiment alumina). The protective layer 13 is porous like the active material layer 12.

Next, the manufacturing apparatus 20 of the electrode 10 will be described.
As shown in FIG. 2, the manufacturing apparatus 20 protects the surface of an electrode material 15 having an elongated strip-like metal foil 11 and an active material layer 12 continuously formed on both surfaces of the metal foil 11 in the longitudinal direction. The layer 13 is to be formed. The manufacturing apparatus 20 includes a transfer device 30 that transfers the electrode material 15. The transport device 30 has a supply reel 31, a plurality of guide rolls 32, and a take-up reel 33. Then, after the electrode material 15 is fed out from the supply reel 31, it passes through the guide roll 32 and is taken up on the take-up reel 33.

  The manufacturing apparatus 20 includes a pre-coating device 40 as a second coating unit that applies the pretreatment material 41 to the surface of the electrode material 15, more specifically, the surface of the active material layer 12 integral with the metal foil 11. The pretreatment material 41 was formed into a slurry by kneading alumina particles 41a (having a particle diameter of about 50 nm) as the second particles, a solvent 41b (N-methyl-2-pyrrolidone) and a binder 41c (polyvinylidene fluoride). It is a thing.

  The pre-coating apparatus 40 has a tank 42 for storing the pre-treatment material 41. An electric ultrasonic vibrator 43 is provided inside the tank 42. The ultrasonic vibrator 43 is for preventing aggregation of alumina particles 41 a and the like in the slurry-like pretreatment material 41.

  The pre-coating apparatus 40 includes a die head 44 for discharging the pretreatment material toward the surface of the active material layer 12 on one surface of the electrode material 15, a communicating pipe 45 communicating the tank 42 and the die head 44, and the communicating pipe 45 And a pump 46 attached to pump the pretreatment material 41. The pre-coating device 40 also has a back roller 47 that supports the electrode material 15 in the vicinity of the die head 44. The discharge port 44 a for discharging the pretreatment material 41 in the die head 44 is disposed to face the back roller 47. The die head 44 and the back roller 47 are formed of a conductive metal material (for example, an iron-based material).

  The manufacturing apparatus 20 further includes a voltage application device 50 as a voltage application unit that applies a predetermined (several volts) DC voltage between the die head 44 and the back roller 47. The voltage application device 50 has a power supply 51. The positive terminal 52 of the power source 51 is connected to the die head 44, and the negative terminal 53 is connected to the back roller 47. When applying the pretreatment material 41 from the die head 44 to the surface of the electrode material 15 by applying a voltage by the voltage application device 50, the portion on the die head 44 side of the pretreatment material 41 existing between the die head 44 and the back roller 47 A DC voltage is applied between the back roller 47 and the portion on the back roller 47 side.

  Furthermore, the manufacturing apparatus 20 includes a protective layer coating apparatus 60 as a first coating unit that applies the protective layer forming material 61 to the surface of the electrode material 15. The protective layer coating device 60 is disposed downstream of the precoating device 40 in the transport direction of the electrode material 15. The protective layer-forming material 61 is formed into a slurry by kneading alumina particles 61a (having a particle diameter of about 2 μm) as first particles, a solvent 61b (N-methyl-2-pyrrolidone) and a binder 61c (polyvinylidene fluoride). It is In the present embodiment, the particle diameter of the alumina particles 41 a contained in the pretreatment material 41 is smaller than the particle diameter of the alumina particles 61 a contained in the protective layer forming material 61.

  The protective layer coating device 60 has a plurality of (five in the present embodiment) injectors 62 arranged in parallel along the electrode material 15. A supply device 63 for supplying a protective layer forming material 61 is connected to each injector 62, and the protective layer forming material 61 is supplied from the supply device 63 to each injector 62.

  The protective layer coating device 60 also has a duct 64 covering the periphery of the electrode material 15 and the injector 62. Then, the protective layer forming material 61 is jetted from the respective injectors 62 toward the surface of the electrode material 15 inside the duct 64. The injection directions of the plurality of injectors 62 are parallel to one another and orthogonal to the electrode material 15. In the protective layer coating device 60, a small amount of the protective layer forming material 61 is divided into a plurality of times and sprayed onto the surface of the electrode material 15. Therefore, the protective layer forming material 61 has less variation in thickness along the longitudinal direction. It is applied to the surface of the electrode material 15.

  The manufacturing apparatus 20 also includes a drying device 70 that dries the electrode material 15. The drying device 70 is disposed downstream of the protective layer coating device 60 in the transport direction of the electrode material 15. The electrode material 15 transported by the transport device 30 can pass through the inside of the drying device 70. The inside of the drying device 70 is supplied with hot air and is high temperature. The slurry-like protective layer forming material 61 dries and hardens while the electrode material 15 passes through the inside of the drying device 70.

Hereinafter, the effect | action by manufacturing the electrode 10 using the said manufacturing apparatus 20 is demonstrated.
The production of the electrode 10 by the production device 20 is performed using the electrode material 15. In addition, since formation of the active material layer 12 which makes a part of electrode material 15 can be implemented by a well-known method, the description is abbreviate | omitted. The active material layer 12 of the electrode material 15 has already been cured, and the active material layer 12 is formed on the metal foil 11, so that the electrode material 15 has a certain degree of rigidity.

As shown in FIG. 2, in the production of the electrode 10, the transport device 30 transports the electrode material 15 having the active material layer 12 on both sides.
Then, the electrode material 15 drawn out from the supply reel 31 passes through the guide roll 32 and is guided by the back roller 47 to a position facing the discharge port 44 a of the die head 44. The pretreatment material 41 is ejected from the ejection port 44 a of the die head 44, and the pretreatment material 41 is applied to the surface of the active material layer 12 on one side of the electrode material 15.

  As shown in FIG. 3A, at this time, in the manufacturing apparatus 20, the pretreatment material 41 is interposed between the die head 44 and the back roller 47, and a predetermined DC voltage is obtained by the voltage application device 50. It will be in the applied state. Therefore, Coulomb force acts between the metal foil 11 conducted to the back roller 47 via the active material layer 12 and the alumina particles 41 a in the pretreatment material 41.

  Thereafter, as shown in FIG. 2, the electrode material 15 is guided into the duct 64 of the protective layer coating device 60. The protective layer forming material 61 is sprayed from the plurality of injectors 62 inside the duct 64, and the protective layer forming material 61 is applied to the surface of the active material layer 12 to which the pretreatment material 41 is previously applied. Thereby, a layer of the protective layer forming material 61 is formed on the surface of the active material layer 12.

  Thereafter, the electrode material 15 is guided to the inside of the drying device 70. Then, the pretreatment material 41 and the protective layer forming material 61 in the slurry state before entering the inside of the drying device 70 dry and harden while passing through the inside of the drying device 70. As a result, the layer of the protective layer forming material 61 becomes the protective layer 13.

Thereafter, the electrode material 15 on which the protective layer 13 is formed is wound around the take-up reel 33 through the guide roll 32.
The electrode material 15 taken up on the take-up reel 33 is drawn out in a separate step and cut into a predetermined shape. And while the active material layer 12 is formed in rectangular shape, the uncoated part 12a and the current collection tab 14 are formed, and the electrode 10 is manufactured.

  The electrode 10 manufactured in this manner is provided with alumina particles 41 a having a small particle diameter in the gaps of the active material in the active material layer 12 and is made of alumina particles 61 a having a relatively large particle diameter covering the surface of the active material layer 12. It is a structure provided with the protective layer 13.

According to the present embodiment, the following effects can be obtained.
(1) The alumina particles 41a can be attracted to the metal foil 11 side by the electrostatic adsorption action by the Coulomb force acting between the metal foil 11 and the alumina particles 41a by the voltage applied by the voltage application device 50. Therefore, as shown in FIG. 3B, the pretreatment material 41 including the alumina particles 41a can be forcibly pushed into the gap of the active material in the active material layer 12, and the gas can be pushed out from the gap. In the present embodiment, since the particle size of the alumina particles 41a is small and easily intrudes into the gaps between the active materials, the alumina particles 41a can be suitably pushed into the gaps. Then, as shown in FIG. 4, the protective layer forming material 61 can be applied to the surface of the active material layer 12 by the protective layer applying device 60 in a state where the gaps between the active materials are narrowed by the pretreatment material 41. Mixture of air bubbles between the metal foil 11 and the protective layer forming material 61 can be suppressed. In the present embodiment, since the alumina particles 61a contained in the protective layer forming material 61 are relatively large and difficult to penetrate into the gaps between the active materials, the protective particles 13 remain on the surface of the active material layer 12 to form the protective layer 13.

  (2) The particles of metal oxide (alumina, magnesia, etc.) are formed in a shape close to a spherical shape, so they are less likely to get caught in the active material and easily enter the gap. In the present embodiment, since the pretreatment material 41 including the alumina particles 41 a is adopted, the gaps of the active material can be suitably filled with the alumina particles 41 a.

  (3) The binder 41c contained in the pretreatment material 41 can bond the alumina particles 41a entering the gaps of the active material layer 12 to the active material or bond the alumina particles 41a to each other. Therefore, the strength of the active material layer 12 can be increased as compared with the case where a pretreatment material not containing the binder 41 c is adopted.

  (4) Since air bubbles are prevented from being mixed between the metal foil 11 and the protective layer forming material 61 when the protective layer 13 is applied, the protective layer 13 can be formed into an appropriate shape with small variation in thickness. The protective layer 13 can provide an appropriate protective function.

The above embodiment may be modified as follows.
As the voltage application device 50, one in which a gradient force acts between the alumina particles 41a in the pretreatment material 41 and the metal foil 11 may be employed. Also by such a manufacturing apparatus, the alumina particles 41a can be attracted to the metal foil 11 by the electrostatic adsorption action by the gradient force.

  ○ The point where the power supply 51 of the voltage application device 50 is connected, such as connecting the positive terminal 52 of the power supply 51 of the voltage application device 50 to the communication pipe 45 or connecting the negative terminal 53 to the metal foil 11 of the electrode material 15 It can be changed arbitrarily.

As the drying device 70, one having a heater inside may be adopted.
The size of the active material and the size of the alumina particles 41a and 61a can be arbitrarily changed. The size of the alumina particles 41 a of the pretreatment material 41 may be a size that easily enters the gaps of the active material layer 12 and is less likely to cause aggregation in the pretreatment material 41. The size of the alumina particles 61 a of the protective layer forming material 61 may be a size that does not easily enter the gaps of the active material layer 12 and easily stay on the surface of the active material layer 12.

  The pretreatment material 41 and the protective layer forming material 61 may include particles of metal oxides other than the alumina particles 41a and 61a (for example, magnesia). In addition, the pretreatment material 41 and the protective layer forming material 61 may be those including particles made of an inorganic material (silicon carbide, silicon oxide, aluminum nitride or the like).

The pretreatment material 41 can be made free of the binder 41c.
The manufacturing apparatus 20 according to the above-described embodiment can be applied to a manufacturing apparatus that manufactures an electrode of the wound and laminated type.

  The manufacturing apparatus 20 of the above embodiment can also be applied to a manufacturing apparatus that manufactures electrodes of power storage devices other than secondary batteries, such as electrodes of capacitors.

  DESCRIPTION OF SYMBOLS 10 ... Electrode 11 11 Metal foil 12 Active material layer 13 Protective layer 15 Electrode material 20 Manufacturing apparatus 40 Pre-coating apparatus 41 Pretreatment material 41a Alumina particles 41b Solvent , 41c: binder, 44: die head, 44a: discharge port, 45: communicating pipe, 47: back roller, 50: voltage application device, 51: power source, 52: positive terminal, 53: negative terminal, 60: protective layer coating device 61: Protective layer-forming material, 61a: alumina particles, 61b: solvent, 61c: binder.

Claims (5)

An apparatus for producing an electrode comprising a porous active material layer on at least one side of a current collector, and a surface of the active material layer covered with a protective layer,
A first application unit for applying a protective layer-forming material including a first particle made of an inorganic material, a binder, and a solvent on the surface of the active material layer integrated with the current collector;
It is a particle made of an inorganic material on the surface of the active material layer integral with the current collector in a step prior to the application of the protective layer-forming material from the first application part, and smaller than the first particle A second application unit for applying a pretreatment material containing second particles and a solvent;
An apparatus for manufacturing an electrode, comprising: a voltage application unit that applies a voltage between the second application unit and the current collector.   The apparatus of claim 1, wherein the second particles are made of metal oxide. The second application unit has a die head for discharging the pretreatment material,
The production apparatus has a transport roller for transporting an electrode material composed of the current collector and the active material layer,
The apparatus according to claim 1, wherein the voltage application unit applies a voltage between the die head and the transport roller.   The said pre-processing material contains the binder, The manufacturing apparatus of the electrode as described in any one of Claims 1-3.   The said electrode is an electrode of a secondary battery, The manufacturing apparatus of the electrode as described in any one of Claims 1-4.