JP4867232B2 - Battery electrode manufacturing method and manufacturing apparatus - Google Patents

Description

  The present invention relates to a method and an apparatus for manufacturing an electrode for a lithium ion secondary battery that is used by being mounted on electronic devices such as notebook personal computers, precision devices, and the like.

  High-performance electronic devices such as video cameras, laptop computers, and mobile phones consume relatively large currents, so the batteries used can withstand heavy loads and have been recharged in recent years in order to save resources. What can be done is being sought. For this reason, a lithium ion secondary battery using a copper foil as a negative electrode current collector is used as a main power source or backup power source for these electronic devices. This lithium ion secondary battery has excellent features such as high energy density, low self-discharge and light weight.

  In the conventional lithium ion secondary battery, as the charge / discharge cycle progresses, lithium grows in a dendrite shape at the time of charging in the negative electrode, and this dendritic crystal may reach the positive electrode and lead to an internal short circuit. Although there was a problem that it was high, the use of a carbon-based material as a negative electrode active material carrier for the negative electrode has greatly improved the characteristics and has been put to practical use.

That is, in a lithium ion secondary battery using a carbon-based material as a negative electrode active material carrier for the negative electrode, the crystal structure of lithium and the positive electrode active material previously supported on the negative electrode carbon-based material by a chemical or physical method is used. Each of lithium contained in (for example, lithium cobaltate LiCoO ₂ ) and lithium dissolved in the electrolyte is doped between the carbon layers and dedoped from the carbon layers at the negative electrode during charging and discharging. For this reason, even when the charge / discharge cycle proceeds, no precipitation of dendrite-like crystals is observed at the time of charging in the negative electrode, and internal short circuit hardly occurs, and good charge / discharge cycle characteristics are exhibited.

Thus, conventionally, as a negative electrode for a lithium ion secondary battery, a material obtained by applying a carbon-based material such as graphite as an active material to a copper foil as a current collector is mainly used. The negative electrode for a lithium ion secondary battery needs to have a large energy that can be taken out per unit weight (high energy density) and an excellent charge / discharge cycle life. From this point, From the viewpoint of graphite, it can be said that although the theoretical energy capacity is low (372 mAh / g), it has an excellent charge / discharge cycle life.
However, in order to cope with further reduction in size and weight in recent years, tin (993 mAh / g) having a high theoretical energy capacity has attracted attention in place of carbon-based materials such as graphite, and lithium ion 2 using tin or a tin alloy as a negative electrode material. Secondary batteries are being put into practical use.

On the other hand, as a battery structure, as shown in FIG. 8, a spiral wound electrode constituted by winding a strip-like positive electrode 2 and a strip-like negative electrode 1 in the length direction thereof via a strip-like separator 3. Body structure is effective. In this wound electrode body structure, since the electrode area can be made large, it can withstand use under heavy loads, which consumes a relatively large amount of current.
In the wound electrode body, it is desirable from the viewpoint of improving battery performance that the electrode area is increased and the electrode is thinned so that the active material or the active material carrier can be filled as much as possible in the limited space.
In FIG. 8, reference numeral 5 is a battery can, 7 is a positive electrode, 11 is a negative electrode lead, and 12 is a positive electrode lead.

The requirements for an electrode provided with an active material on a copper foil to be a current collector are as follows: a) it is porous so that lithium ions associated with charge / discharge are easily transmitted; b) low electrical resistance so as to ensure a sufficient electron conduction path; c) high active material filling.
And the thing currently disclosed by patent documents 1-5 is conventionally known for the electrode by which an active material is provided on the copper foil used as an electrical power collector, and its manufacturing method.

Patent Document 1 describes an electrode plate for a non-aqueous electrolyte secondary battery represented by a lithium ion secondary battery and a method for producing the electrode plate.
The method for producing an electrode plate for a non-aqueous electrolyte secondary battery includes a step of kneading at least an active material and a binder (binder) to prepare an electrode coating solution, and collecting the electrode coating solution. A non-aqueous electrolyte secondary battery electrode comprising a step of coating on an electric body and a step of drying a coating liquid coated on the current collector to form a coating film containing an active material A method for producing an electrode plate for a non-aqueous electrolyte secondary battery for producing a plate, wherein the electrode coating solution is divided into two or more coating steps and a drying step, and is applied and dried to give a predetermined film thickness. The film thickness is formed on the current collector, and the dry film thickness of the coating film formed by the first coating process and the drying process is only the second time formed by the second coating process and the drying process. If the coating thickness is greater than the dry film thickness of the coating film and the number of coatings is further increased, it is formed in each step as the number of coatings increases. Dry thickness of the coating film is one that was constructed so as to decrease successively to.

  In this method of manufacturing an electrode plate for a non-aqueous electrolyte secondary battery, when an electrode coating solution is applied and dried on a current collector to form a coating film, binding at the current collector interface is performed. By forming a coating film without reducing the amount of agent present, it is possible to form a sufficiently thick coating film without impairing the adhesion between the current collector and the coating film. In addition, by enabling fast drying, it is possible to improve productivity in manufacturing the electrode plate.

Patent Document 2 describes a method for manufacturing an electrode for a lithium ion secondary battery in which an active material layer is formed on a current collector.
In this method for producing an electrode for a lithium ion secondary battery, an active material layer containing an active material to be alloyed with lithium is deposited by using a vapor deposition method in which a vapor deposition material included in a vapor deposition source is heated to evaporate and deposit. A step of forming on a current collector containing a metal that does not alloy with lithium, and at the time of evaporating and depositing the vapor deposition material contained in the vapor deposition source by heating, at least 1 is provided between the current collector and the vapor deposition source. A step of physically shutting off times.

  In this method for manufacturing an electrode for a lithium ion secondary battery, during deposition, the current collector and the vapor deposition source are physically interrupted at least once, so that deterioration due to temperature rise of the current collector is not caused. In addition to being suppressed, heating of the active material layer on the current collector is also suppressed, so that the amount of oxygen introduced into the active material layer can be reduced. As a result, it is possible to suppress a decrease in initial charge / discharge characteristics and charge / discharge cycle characteristics as well as a decrease in capacity.

Patent Document 3 describes a material for a negative electrode for a non-aqueous secondary battery using reversible occlusion / release of alkali metal ions typified by a lithium ion secondary battery.
The method for producing a negative electrode material for a non-aqueous secondary battery is a method for producing a negative electrode material for a non-aqueous secondary battery including a step of heating and melting a raw material to obtain a melt, and a step of solidifying the melt. In the process of melting the raw material and the process of solidifying the melt, the process in which the temperature of the material is in the temperature range of 300 ° C. or higher is performed in a non-oxidizing atmosphere.

  In this method for producing a negative electrode material for a non-aqueous secondary battery, both the discharge capacity and the cycle life can be achieved by setting the specific electrical resistance of the powder of the negative electrode material for the non-aqueous secondary battery made of an alloy powder to a certain value or less. A good negative electrode material can be obtained reliably.

Patent Document 4 is not intended for a lithium ion secondary battery, but a secondary battery capable of improving basic performance as a secondary battery such as a nickel metal hydride battery or a nickel cadmium hydrogen battery used in an electric vehicle or the like. A method for manufacturing a battery negative electrode plate is described.
In this method of manufacturing a secondary battery negative electrode plate, a hydrogen storage alloy powder is supplied to the surface of the core material while being rolled while passing through a thin plate-shaped core material having a large number of through holes between a pair of rolling rolls. The hydrogen storage alloy powder is sintered and fixed to both surfaces of the core material.

In this method of manufacturing a secondary battery negative electrode plate, the hydrogen storage alloy powder can be firmly bonded to the core material without using an organic binder, and the particles can be firmly bonded to each other. Can be electrically connected and a large contact area between the core material and the hydrogen storage alloy powder can be secured to form a good conductive network.
JP 09-134718 (lower left of page 2, upper right of page 3) Japanese Patent Laying-Open No. 2005-158633 (2nd page, lower left, FIG. 2) JP-A-2002-246017 (from page 2, lower left to upper right, page 9, right) JP 2001-68105 A (2nd page, 6th page, lower right, FIG. 2)

However, a conventionally known method for producing an electrode is described in Patent Document 1, wherein an active material and a binder (binder) are kneaded and an electrode coating solution is applied onto a current collector. In the method of forming an electrode by drying, the active material can be made porous because the binder is removed by drying, but the presence of the binder itself hinders the improvement of the filling degree of the active material. As well as an increase in electrical resistance.
Moreover, in the method of depositing an active material for a battery on a current collector by vapor deposition or the like described in Patent Document 2, the filling rate of the active material itself is improved, but the film may be made porous. It is difficult and there is a disadvantage that current capacity cannot be obtained because the permeability of lithium ions becomes insufficient.

In addition, the method of melting and solidifying by heating described in Patent Document 3 generally involves heating and cooling by batch processing, which has the disadvantage of increasing the heat treatment time.
Furthermore, in the method described in Patent Document 4 in which only the alloy powder is sintered and fixed to the core material using a rolling roll without a binder, the alloy powders are porous and have a low electrical resistance, and a filling rate is ensured. However, it is necessary to use a core material having a certain thickness and strength, which disadvantageously increases the thickness of the negative electrode plate itself.

  In view of this point, the present invention proposes a manufacturing method and a manufacturing apparatus for a battery electrode that have good productivity and are suitable for use in a lithium ion secondary battery.

To solve the above problems, the present invention is method of manufacturing a battery electrode to fix the active material on a current collector substrate, the predetermined supplying powdery active material on a current collector substrate thinness of The first step of forming a layer, and a layer formed of a powdery active material are scanned with an electron beam, and the powdered active material is bound and the active material is collected by the irradiation heat of the electron beam. and a second step for fixing to the substrate, the one in which the active material of the first and second step on a current collector substrate was performed repeatedly until a layer of predetermined thickness.

  According to the battery electrode manufacturing method configured as described above, the powdered active material thinly provided on the current collecting base material is irradiated with an electron beam to slightly dissolve the powdered active material, and the powder The body-shaped active material and the current collecting base material can be fixed. Then, a new active material layer can be bonded to the previous active material by irradiating an electron beam after providing a powdery active material layer on top of this. The active material can be formed on the current collecting base material repeatedly without using a binder (binder) up to a predetermined thickness. Further, the filling rate can be adjusted by changing the porous state after the binding according to the powder particle size of the active material and the heating conditions.

  According to the present invention, in the method for manufacturing a battery electrode described above, the second step is performed in a vacuum chamber.

  According to the battery electrode manufacturing method configured as described above, an increase in electrical resistance due to oxidation of the current collecting base material and the active material can be suppressed.

  Moreover, this invention makes the current collection base material copper foil in the manufacturing method of the battery electrode described above, and the current collection base material is drawn out from the copper foil roll and continuously supplied.

  According to the battery electrode manufacturing method configured as described above, it is possible to continuously perform the process of fixing the active material to the current collector base material of the copper foil and binding the active materials to each other.

In order to solve the above-described problems, the battery electrode manufacturing apparatus of the present invention includes a supply roll for supplying a foil-like current collecting base material, a winding roll for winding up the current collecting base material after the treatment, An electron beam source, a scanning mechanism for the electron beam, a supply mechanism for the powdered active material of the battery electrode, a squeegee for providing the powdered active material on the current collector, and a powdered active material A squeegee drive mechanism that adjusts the squeegee height and moves the squeegee to form a material in a predetermined thin layer on the current collecting substrate, and a vacuum chamber that blocks the scanned electron beam from the atmospheric atmosphere. The powdered active material is supplied onto the current collecting base fed from the supply roll to form a layer having a predetermined thickness by a squeegee, and an electron beam is applied to the layer formed of the powdered active material. Of powdered active materials and current collection by active heat It is obtained to carry out the fixing of the wood.

  According to the apparatus for manufacturing an electrode for a battery of the present invention configured as described above, the active material is continuously fixed to the roll-shaped current collecting base material while avoiding an increase in electrical resistance due to oxidation, and the active materials are bonded to each other. A battery electrode can be produced by binding.

  According to the method for manufacturing an electrode for a battery of the present invention, the formation of an active material on a current collecting base material can be continuously performed without using a binder (binder), so that production efficiency is ensured. It is possible to improve the filling property of the active material and the electrical resistance, and adjust the porosity of the active material according to the particle size of the powder and the heating conditions, thereby improving the lithium ion permeability. .

  In addition, according to the battery electrode manufacturing apparatus of the present invention, it is possible to continuously produce a battery electrode in which an active material is fixed to a roll-shaped current collecting base material while avoiding an increase in electrical resistance due to oxidation. it can.

  An example of the best mode for carrying out the method and apparatus for producing a battery electrode of the present invention will be described with reference to FIGS.

First, the battery electrode of this example will be described.
As a battery structure in which the electrode of this example is used, as shown in FIG. 8, a spiral formed by winding a strip-shaped negative electrode 1 and a strip-shaped positive electrode 2 through a strip-shaped separator 3 in the length direction thereof. The description will be made with reference to a wound electrode body structure. In this wound electrode structure, since the electrode area can be increased, it can withstand use in an electronic device that consumes a relatively large amount of current and has a heavy load.
In the wound electrode body, the electrode is thinly formed so that the electrode area is increased from the viewpoint of improving the battery performance and the active material or the active material carrier can be filled in the limited space as much as possible.
Hereinafter, the negative electrode will be described as an example.

FIG. 2 is a perspective view of the negative electrode material 41 in which the strip-shaped negative electrode 1 of the lithium ion secondary battery shown in FIG. 8 is taken out and developed. In the figure, 41a is a copper foil as a negative electrode current collector, and 41b is a negative electrode active material made of Cu (copper) powder and Sn (tin) powder formed in layers on the surface of the copper foil 41a.
Thus, the negative electrode material 41 formed in a strip shape is wound together with the positive electrode material 42 through the separator 3, and is housed as the negative electrode 1 and the positive electrode 2 as shown in FIG.

FIG. 3 is a schematic diagram of a structure showing an enlarged cross section of the negative electrode material 41. The negative electrode material 41 has a thickness of about 50 μm on one surface of a copper foil 41 a having a thickness of about 20 μm, for example, a powder 40 in which Cu powder having a particle diameter of 20 μm and Sn powder are mixed at a weight ratio of 1: 1. Thus, it is fixed without using a binder.
At this time, the mixed powder 40 serving as the negative electrode active material 41b is fixed by melting on one surface of the copper foil 41a, and further, the Cu powder and the Sn powder constituting the powder 40 are not completely dissolved under heating conditions. Only their surfaces are melted and bound together. Then, a space through which lithium ions can pass between the particles of the mixed powder 40 is left.

Next, the manufacturing apparatus of this negative electrode material 41 is demonstrated with reference to FIG.1, FIG.4, FIG.5.
FIG. 1 is an explanatory diagram of a configuration of a manufacturing apparatus for the negative electrode material 41. The manufacturing apparatus for the negative electrode material 41 is mainly composed of an electron beam irradiation mechanism 57 and a processing chamber 60.

As shown in FIG. 1, the processing chamber 60 has a feeding roll 52 for supplying the copper foil 50 wound in a roll shape, a winding roll 53 for winding the processed copper foil 50, and a roll drive (not shown). A control mechanism, a hopper 55 for supplying the mixed powder 40, a squeegee 56 for leveling the mixed powder 40 supplied onto the copper foil 50 to a predetermined thickness, and a squeegee driving mechanism 51 for driving the squeegee 56. , And an irradiation unit 59 of the electron beam irradiation mechanism 57 is provided.
The processing chamber 60 is configured to be evacuated independently by a work opening / closing door (not shown) and a vacuum exhaust device.

The copper foil 50 has a thickness of, for example, about 20 μm, a width of about 300 mm, and a length of several meters, and is initially wound around the feeding roll 52. One end is fixed to the winding roll 53. Then, a predetermined amount of movement is possible in the left and right directions of the double arrow shown in FIG. 1 by a roll drive control mechanism (not shown).
The hopper 55 is a trumpet-shaped container provided with a lid that allows a slit-shaped opening provided at the bottom to be opened and closed. Then, the powder 40 supplied into the hopper 55 is elongated in the width direction on the copper foil 50 by opening the bottom lid for a predetermined time.
The powder 40 is supplied to the hopper 55 through a pipe 55a extending to the outside of the processing chamber 60. The pipe 55a is provided with a valve 55b for maintaining a vacuum.

The squeegee 56 equalizes the powder 40 supplied onto the copper foil 50 so as to have a predetermined thickness, and is made of a metal having wear resistance to ensure the accuracy of the thickness of the powder 40. Is done.
The squeegee driving mechanism 51 allows the squeegee 56 to be lowered so as to have a predetermined gap between the squeegee 56 and the upper surface of the copper foil 50 as shown by an arrow in FIG. A squeegee operation can be performed.
An electron beam irradiation unit 59 to be described later is provided above the processing chamber 60, and a beam collector 60a is provided on the lower side of the copper foil 50 facing the irradiation unit 59.

As shown in FIG. 4, the electron beam irradiation mechanism 57 includes a power supply unit 58, an irradiation unit 59, a control unit (not shown), and the like.
The power supply unit 58 includes a filament power supply 58a for generating thermoelectrons, an extractor power supply 58b for extracting the generated electron beam, and a high voltage power supply 58c for accelerating the electrons.

The irradiation unit 59 draws out the thermoelectrons generated by the plurality of filaments 59a provided side by side in the vacuum container by the extra grid 59b, and further generates electrons by a high voltage (70 to 300 kV) applied between the terminal grid 59c. Accelerate at a stretch. Then, the accelerated electrons become an electron current, pass through the window foil (thin titanium foil) 59d, and jump out to the processing chamber 60 side. At this time, secondary X-rays are shielded by a beam collector 60a provided in the processing chamber 60 (self-shielding structure).
Then, the vacuum vessel 59d is evacuated by a dedicated evacuation system 59e so as to achieve a high degree of vacuum, and an electron mean free process is ensured so that an electron beam can be irradiated in a curtain shape without losing kinetic energy.

As shown in FIG. 4, the irradiation unit 59 and the processing chamber 60 are separated from each other, and an electron beam from the irradiation unit 59 can be introduced into the processing chamber 60 through the window foil 59 d. I have to.
Here, the window foil 59d is made of, for example, a thin titanium foil, maintains the vacuum of the irradiation unit 59, and returns to atmospheric pressure due to a vacuum break when supplying the copper foil 50 and the mixed powder 40 into the processing chamber 60. Is divided so as not to affect the irradiation unit 59.
In this example, the copper foil 50 serving as the negative electrode material 41 is set on the feeding roll 20 and the winding roll 21, and the processing chamber 60 is evacuated as a whole with the mixed powder 40 supplied to the hopper 55. Therefore, the exhaust port is disposed so that the powder 40 does not rise greatly during exhaust.

In the negative electrode material 41 manufacturing apparatus configured as described above, first, the copper foil 50 is set on the feeding roll 20 and the winding roll 21 in the processing chamber 60, and the mixed powder 40 is supplied to the hopper 55 and then the valve. 55b (FIG. 1) is closed. Then, the processing chamber 60 is evacuated until a predetermined degree of vacuum is reached.
Next, after supplying the powder 40 from the hopper 55 onto the copper foil 50, the copper foil 50 is moved by the roll drive mechanism, and the powder 40 is leveled to a predetermined thickness and width by the squeegee 56.

  Then, in this state, the electron beam made into a curtain shape from the irradiation unit 59 is irradiated in the front-rear direction shown in FIG. 1, and the copper foil 50 is moved slowly to the right. Thereby, about the desired range of the uniformed powder 40, it can irradiate and heat an electron beam from the upper direction, and can fix the powder 40 on the copper foil 50, and can bind the powder 40 together. .

Hereinafter, the manufacturing method of the negative electrode material 41 is demonstrated with reference to FIG. 1, FIG.
5 and 6 omit the processing chamber 60 for the sake of explanation.

First, the processing chamber 60 shown in FIG. 1 is returned to atmospheric pressure, a work door (not shown) is opened, a roll of the copper foil 50 is set on the feeding roll 52, and one end is fixed to the winding roll 53. Then, the working door of the processing chamber 60 is closed. On the other hand, the mixed powder 40 of the electrode active material is supplied to the hopper 55 from a pipe 55a extending to the outside of the processing chamber 60, and then the valve 55b is closed.
Then, the processing chamber 60 is evacuated to a predetermined vacuum level.

The supply of the mixed powder 40 onto the copper foil 50 in the state of the desired degree of vacuum will be described with reference to side views 5A to 5D and plan views 6A to 6E.
First, as shown in FIGS. 5A and 6A, a predetermined amount of the mixed powder 40 in the hopper 55 is supplied onto the copper foil 50.
5B and 6B, the copper foil 50 is driven in the direction of the arrow by a predetermined distance by a roll drive control mechanism (not shown) so that the powder 40 is arranged on the right side of the squeegee 56 shown in the drawing. Is done. That is, the copper foil 50 is fed out from the feeding roll 52 by a predetermined amount and wound up on the winding roll 53.

Thereafter, as shown in FIG. 5C, the squeegee 56 is lowered and driven by the squeegee driving mechanism (FIG. 1) so that the lower surface of the squeegee 56 has a predetermined gap, for example, 50 μm, with respect to the upper surface of the copper foil 50. 56 is driven in the direction of the arrow shown in FIGS. 5C and 6C. At this time, the powder which is made into a thin layer is shown by 40a.
Then, as shown in FIG. 5D, the squeegee 56 itself is returned to the original position shown in FIG. 5A.

  Next, as shown in FIG. 6D, while the copper foil 50 is slowly moved in the right direction as shown in the figure, an electron beam is irradiated and heated from above the powder 40a, and a thin layer of the copper foil 50 and the powder 40a. And the powders 40 are bound together. This powder fixed to a thickness of about 50 μm is indicated by 40b. The fixed powder 40b becomes the negative electrode active material 41b.

When the negative electrode active material 41b is formed thicker, the copper foil 50 is rewound in the left direction shown in FIG. 6D to the position shown in FIGS. 5A and 6A, and the powder 40 is further supplied. The powder 40b fixed by the procedure of FIGS. 5A to 5D and FIGS. 6A to D similar to the above after being lowered from the upper surface of 50 to a height of, for example, 100 μm can be further laminated.
As shown in FIG. 6E, when the negative electrode active material 41b having a desired thickness is formed by the lamination process of the powder 40, the copper foil 50 is moved in the right direction indicated by the arrow in the drawing, and the negative electrode active material A predetermined amount of the copper foil 50 on which 41b is formed is wound on a winding roll 53.

By repeating the processes shown in FIGS. 5A to 5D and FIGS. 6A to 6E, a plurality of strip-shaped negative electrode active materials 41b are continuously formed on the rolled copper foil 50. And the copper foil roll in which the strip | belt-shaped negative electrode active material 41b of the winding roll 53 was formed in plural is cut out to a predetermined dimension by another shaping processing apparatus, and it is set as the negative electrode material 41. FIG.
The thickness of the powder 40 that is leveled by the squeegee 56 on the copper foil 50 is such that when the electron beam is irradiated by the electron beam irradiation mechanism 57, the copper foil 50 and the powder 40a are fixed and the powder 40a is fixed. As long as 40 are bound together, the thickness is not limited to the thickness of about 50 μm shown here, and can be appropriately changed depending on the performance of the electron beam irradiation mechanism 57.

  Embodiments according to the present invention will be described below with reference to FIGS.

  FIG. 7 is a schematic longitudinal sectional view of the lithium ion secondary battery of this example, and FIG. 2 is a perspective view of a strip-like negative electrode material 41 that can be used in this battery. This battery was produced as follows.

First, as the strip-like negative electrode material 41, a mixed powder 40 of Cu powder and Sn powder (weight ratio 1: 1) each having a particle diameter of 20 μm is prepared, and this is squeegee 56 so that the thickness is 50 μm. Level on foil 50. The copper foil 50 was heated and sintered by a laser while being moved by winding to produce an electrode. The atmosphere was a vacuum degree of 10 ⁻⁴ to 10 ⁻⁶ × 133.3 Pa used for electron beam welding or the like.
The film thickness of the layer of the negative electrode active material 41b after molding was approximately 50 μm because it was not completely dissolved, and the width of the strip-shaped negative electrode material 41 was 41.5 mm and the length was 280 mm.

Next, the positive electrode material 42 was produced as follows. LiCoO ₂ was obtained by mixing 0.5 mol of lithium carbonate and 1 mol of cobalt carbonate and firing in air at 900 ° C. for 5 hours.
Using this LiCoO ₂ as a positive electrode active material, 6 parts by weight of graphite as a conductive agent and 3 parts by weight of polyvinylidene fluoride as a binder were mixed with 91 parts by weight of LiCoO ₂ to prepare a positive electrode active material. This positive electrode active material was dispersed in a solvent N-methyl-2-pyrrolidone to form a slurry (paste).

  Next, this positive electrode active material slurry is uniformly applied to both surfaces of the positive electrode current collector 10 which is a strip-shaped aluminum foil having a thickness of 20 μm. The solvent was dried, and after this drying, compression molding was performed with a roller press to obtain a strip-like positive electrode material 42 having layers of the positive electrode active material 42a on both surfaces of the positive electrode current collector 10.

  The film thickness of the positive electrode active material 42a after molding was the same at both sides of 80 μm, and the width of the strip-like positive electrode material 42 was 39.5 mm and the length was 230 mm.

  Using the strip-shaped negative electrode material 41, the strip-shaped positive electrode material 42, and the pair of strip-shaped separators 3 a and 3 b made of a microporous polypropylene film having a thickness of 25 μm and a width of 44 mm, the negative electrode The material 41, the separator 3a, the positive electrode material 42, and the separator 3b are laminated in this order in four layers, and the laminated electrode body of this four-layer structure is wound many times in a spiral shape with the negative electrode material 41 inside along the length direction. Thus, a wound electrode body 15 was produced. At this time, the final winding end of the wound electrode body 15 was fixed with an adhesive tape.

  The inner diameter of the hollow portion at the center of the wound electrode body 15 was 3.5 mm, and the outer diameter was 13.9 mm. Note that the core 33 is located in this hollow portion.

  The spiral wound electrode body 15 produced as described above was housed in an iron battery can 5 plated with nickel as shown in FIG.

  Further, in order to collect the current of the negative electrode material 41 and the positive electrode material 42, the negative electrode lead 11 made of nickel is previously attached to the negative electrode current collector 41a, which is led out from the negative electrode material 41 and welded to the bottom surface of the battery can 5. In addition, the positive electrode lead 12 made of aluminum was previously attached to the positive electrode current collector 42 a, which was led out from the positive electrode material 42 and welded to the protruding portion 34 a of the metal safety valve 34.

  Thereafter, a non-aqueous electrolyte solution in which LiPF6 as a lithium salt is dissolved at a ratio of 1 mol / 1 mol in an equal volume mixed solvent of propylene carbonate and 1,2-dimethoxyethane is injected into the battery can 5 and wound. The electrode body 15 was impregnated.

  Before and after this, disk-shaped insulating plates 4 a and 4 b were respectively disposed in the battery can 5 so as to face the upper end surface and the lower end surface of the wound electrode body 15.

  Thereafter, the battery can 5 is sealed by caulking the battery can 5, the safety valve 34 whose outer periphery is in close contact with each other, and the metal battery lid 7 through an insulating sealing gasket 6 having asphalt coated on the surface thereof. did. Thereby, the battery lid 7 and the safety valve 34 were fixed, and the airtightness in the battery can 5 was maintained. Further, at this time, the lower end of the gasket 6 in FIG. 7 is in contact with the outer peripheral surface of the insulating plate 4 a, so that the insulating plate 4 a is in close contact with the upper surface side of the wound electrode body 15.

  As described above, a cylindrical lithium ion secondary battery having a diameter of 14 mm and a height of 50 mm was produced. The battery of Example 1 is referred to as battery A for convenience.

  The cylindrical lithium ion secondary battery includes a safety valve 34, a stripper 36, and an intermediate fitting made of an insulating material for integrating the safety valve 34 and the stripper 36 in order to form a double safety device. 35. Although not shown in the drawings, the safety valve 34 is provided with a cleaving portion that cleaves when the safety valve 34 is deformed, and the battery lid 7 is provided with a hole.

Comparative example

  The negative electrode material was used in the conventional structure, and the others were produced by the same procedure as the battery A described above.

  After oxygen crosslinking in which 10 to 20% by weight of a functional group containing oxygen is introduced into petroleum pitch as a starting material for the negative electrode material, the oxygen-crosslinked precursor is fired at 1000 ° C. in an inert gas stream. As a result, a carbonaceous material having properties similar to glassy carbon was obtained. This carbonaceous material was pulverized to obtain a carbonaceous material powder having an average particle size of 10 μm.

  The carbonaceous material obtained as described above is used as a negative electrode active material carrier, 90 parts by weight of the powder of the carbonaceous material and 10 parts by weight of polyvinylidene fluoride (PVDF) as a binder are mixed, and the negative electrode active material Was prepared. This negative electrode active material was dispersed in N-methyl-2-pyrrolidone as a solvent and slurried (pasted).

  Next, the negative electrode active material slurry was uniformly applied to both surfaces of the negative electrode current collector 41a, which is a strip-shaped copper foil having a thickness of 10 μm, and then the natural convection type electric dryer at 90 ° C. The solvent was dried, and after this drying, compression molding was performed with a roller press to obtain a strip-like negative electrode material 41 having negative electrode active material layers on both sides of the negative electrode current collector 41a as shown in FIG. The drying was performed in the above-described natural convection type electric dryer while the set temperature was 90 ° C. and the air was naturally convected while the atmospheric temperature in the electric dryer was 90 ° C.

  The film thickness of the negative electrode active material after molding was 80 μm on both sides, and the width of the strip-shaped negative electrode material 41 was 41.5 mm and the length was 280 mm.

  The positive electrode material 42 described in Example 1 was combined with the negative electrode material 41 to produce a cylindrical lithium ion secondary battery having a diameter of 14 mm and a height of 50 mm. The battery of this comparative example is referred to as battery B for convenience.

As a result of measuring the battery capacities of the batteries A and B thus produced, it was found that the battery capacity of the battery A was 1.5 times that of the battery B.
This is because the negative electrode material 41 heat-treats the mixed powder 40 of Cu powder and Sn powder so as to have appropriate porosity, so that it absorbs lithium ions more efficiently than the carbonaceous material by the battery B. This is thought to be due to the ability to release.

  According to the method for manufacturing a battery electrode of this example, since a binder (binder) is unnecessary and the treatment is performed in a vacuum atmosphere, the filling property of the electrode active material and the electrical resistance can be reduced. Since the porous property of the electrode active material can be optimized by an electron beam with good controllability, the diffusibility of lithium ions can be ensured and the cycle life can be improved.

  According to the battery electrode manufacturing apparatus of the present example, the electrode active material of the mixed powder is continuously fixed to the copper foil current collecting base while avoiding an increase in electrical resistance due to oxidation, and the powder active Substances can be bound to each other, and a battery electrode can be efficiently produced.

  Of course, the battery electrode manufacturing method and manufacturing apparatus of the present invention are not limited to the above-described examples, and various other configurations can be adopted without departing from the gist of the present invention.

It is a figure where it uses for description of a structure of an example of embodiment of the manufacturing apparatus of the electrode for this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is an external appearance perspective view which showed an example of the form of the negative electrode material used as the negative electrode of this invention battery electrode, and was made into strip | belt shape. It is explanatory drawing which shows the cross-section of the negative electrode material of the battery of the example of FIG. It is explanatory drawing which shows the structure of an example of the electron beam irradiation mechanism of the manufacturing apparatus of the example of FIG. 1 shows an example of a processing procedure according to an embodiment of a method for producing an electrode for a battery of the present invention, wherein A is supply of a mixed active material powder of a negative electrode onto a copper foil, B is movement of the mixed active material powder, and C is a squeegee. D is an explanatory view showing a heat treatment (on the way) by an electron beam. It is explanatory drawing which looked at the processing procedure of the example of FIG. 5 from the upper direction of copper foil, A is supply to the copper foil of the mixed active material powder of an electrode, B is a movement of mixed active material powder, C is by a squeegee. It is explanatory drawing which shows the movement of a heat processing part, D is the heat processing by an electron beam, D is the heat processing by a powder. It is a schematic longitudinal cross-sectional view of the lithium ion secondary battery using the negative electrode material of this example. It is explanatory drawing of the structure of a lithium ion secondary battery.

Explanation of symbols

  40 ... Mixed powder, 41b ... Negative electrode active material, 50 ... Copper foil, 52 ... Feeding roll, 53 ... Winding roll, 56 ... Squeegee

Claims (4)

In the method for producing a battery electrode for fixing an active material on a current collecting substrate,
Supplying a powdery active material on the current collecting substrate to form a layer having a predetermined thickness;
The layer formed of the powdered active material is scanned with an electron beam, and the powdered active materials are bonded to each other and the active material is fixed to the current collecting base material by irradiation heat of the electron beam. A second step of performing
The a method of manufacturing the first and second said steps on said current Denmoto material active material a predetermined repetition until a thick layer performed as in the batteries electrode. In the manufacturing method of the battery electrode of Claim 1,
Manufacturing method of the second step to the batteries for electrodes is performed in a vacuum chamber. In the manufacturing method of the electrode for batteries of Claim 1 or 2 ,
The collector substrate and a copper foil, a manufacturing method of batteries for electrodes to the collector substrate is continuously fed is unwound from foil rolls. A supply roll for supplying a foil-shaped current collecting substrate;
A winding roll for winding the current collecting base material after the treatment;
An electron beam source for heat treatment;
A scanning mechanism of the electron beam;
A supply mechanism of a powdered active material of a battery electrode;
A squeegee for providing the powdery active material on the current collector;
A squeegee drive mechanism for adjusting the squeegee height and moving the squeegee to form the powdered active material in a predetermined thin layer on the current collector base;
A vacuum chamber for shielding the scanned electron beam from the atmospheric atmosphere;
And supplying the powdery active material onto the current collecting base material fed from the supply roll to form a layer having a predetermined thickness by the squeegee, and by the powdery active material production of the powdery active material between the binder and the active the current collector in the batteries for the electrode to perform the fixing to the substrate material by irradiation heat of scanning the electron beam to the formed layer apparatus.

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