JP2011154786A - Apparatus for manufacturing electrode plate of electrochemical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a negative electrode for lithium ion secondary battery that prevents deterioration caused by uneven composition when applying lithium to an active material film by using the active material film having thick and thin portions. <P>SOLUTION: The apparatus has: a feed system that is disposed in a vaccum chamber that is depressurized by a scavenging pump and feeds a substrate; a half seal type material application source with an opening surface that is disposed near the substrate and that applies material steam to the substrate; a heating source that heats the application source; and a slit structure that is disposed near the opening surface of the application source and that applies directivity to the material steam. In the slit structure of the film-forming device of the electrochemical device, an incident direction of the material steam heading for the substrate is reversed with respect to a normal line of the substrate accompanying the feeding of the substrate in a film-forming region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an apparatus for manufacturing an electrode plate for a lithium ion secondary battery.

  In recent years, in order to increase the capacity of lithium ion secondary batteries, alloy-based negative electrode active materials containing elements such as Si (silicon) and Sn (tin) have attracted attention as negative electrode active materials (hereinafter also referred to as active materials). . For example, the theoretical discharge capacity of Si is about 4199 mAh / g, which is about 11 times the theoretical discharge capacity of graphite.

  However, when these alloy-based negative electrode active materials occlude lithium ions, the crystal structure greatly changes and expands. As a result, the electrode plate is deformed, and accordingly, the active material particles are cracked or the active material layer is peeled off from the current collector, thereby lowering the electronic conductivity between the active material and the current collector. As a result, battery characteristics such as cycle characteristics deteriorate.

  For this reason, it has been proposed to provide an expansion space in advance in the active material layer during occlusion of lithium ions.

  Patent Document 1 discloses a negative electrode for a lithium secondary battery in which a thin film made of a metal alloyed with Li or an alloy containing this metal is formed on a current collector made of a material that is not alloyed with Li (hereinafter referred to as a negative electrode). (Also called). In this conventional example, a columnar negative electrode active material is selectively formed in a predetermined pattern on a current collector, and the volume expansion of the active material is absorbed by voids formed between the columnar negative active materials. The content to avoid the destruction of the substance is disclosed.

  Patent Document 2 proposes that charge and discharge cycle characteristics are improved by providing protrusions on the surface of the current collector foil. In this conventional example, the contact area at the interface between the active material thin film and the current collector can be increased by forming the active material thin film on the current collector having a surface roughness Ra of 0.01 microns or more. It is shown that the adhesion between the active material thin film and the current collector can be improved. For this reason, it is disclosed that peeling of the active material thin film from the current collector can be prevented and good charge / discharge cycle characteristics can be obtained.

  As another approach for countermeasures against expansion of the active material accompanying lithium occlusion / release, it is attempted to reduce expansion and contraction by using Si, Sn oxide, nitride or oxynitride although the discharge capacity is slightly reduced. (Patent Document 3). When an oxide, nitride or oxynitride of Si or Sn is used as an active material, irreversible capacity is generated. That is, a part of lithium occluded in the negative electrode active material during charging stays in the negative electrode without contributing to discharge. As a result, the charge / discharge efficiency is lowered, and the irreversible capacity greatly reduces the battery capacity.

  In order to solve this problem, it is effective to previously apply lithium corresponding to the irreversible capacity to the negative electrode. As a method for applying lithium, after forming a battery and charging it corresponding to an irreversible capacity, a negative electrode is taken out and combined with another positive electrode to form a battery (hereinafter this method is referred to as an electrochemical method). ) In addition, a method of applying lithium to the negative electrode plate by a thin film process (hereinafter, this method is referred to as a direct application method) has been proposed.

In order to cope with the expansion of the active material, it is effective to provide a space in the active material layer. That is, as shown in FIG. 15, when the active material layer 103 has a thick portion 105 and a thin portion 107 of the active material, lithium is uniformly applied to the surface of the active material layer 103. In the thin portion 107 of the active material, the ratio of lithium to the active material is high, and in the thick portion 105 of the active material, the ratio of lithium is low. As a result, lithium is insufficient in the thick portion 105 of the active material, and lithium is excessive in the thin portion 107 of the active material.

  In particular, in the thin portion 107 of the active material, surplus lithium may be deposited, and a good charge / discharge cycle may not be obtained. In order to solve this problem, in Patent Document 4, a negative electrode active material layer including a plurality of columnar bodies protruding outward from the surface of the current collector and a thin film body covering at least a part of the current collector surface Then, when supplying lithium to each columnar body by a dry film forming method, it is disclosed that the lithium supply direction is inclined with respect to the axial direction of the columnar body. Moreover, providing lithium from two side surfaces of the columnar body is disclosed. According to these, since lithium is mainly applied to the thick part of the active material, it is possible to prevent excess lithium from being deposited in the thin part of the active material.

JP 2004-127561 A JP 2001-533573 A JP 2002-356314 A JP 2009-152189 A

  As a method for selectively and uniformly applying lithium to a thick portion of the active material, it is effective to set the direction of lithium application to a plurality of directions, but as illustrated in FIG. 4 of Patent Document 4, In order to apply lithium to the active material from two directions, a large facility is required. Therefore, a method for realizing this by a simple method has been demanded.

  In order to solve the above-described problems, an electrochemical element electrode plate manufacturing apparatus according to the present invention is arranged in a vacuum chamber that is depressurized by an exhaust pump, and a transport system that transports a substrate, and a substrate that is disposed in the vicinity of the substrate. A material application source having a semi-enclosed structure having an opening surface for applying a material vapor, a heating source for heating the application source, and a slit structure arranged near the opening surface of the application source to impart directivity to the material vapor The slit structure is a structure in which the incident direction of the material vapor toward the substrate is reversed across the substrate normal as the substrate is transported in the film formation region. .

  According to the electrode plate manufacturing apparatus for an electrochemical element of the present invention, lithium application according to the thickness of the active material can be efficiently performed by a thin film process. As a result, it is possible to prevent the battery characteristics from being deteriorated during cycle charge and discharge.

Schematic sectional view of an example of an apparatus for applying lithium on the active material layer of the present invention Schematic sectional view of an example of an apparatus for applying lithium on the active material layer of the present invention Schematic sectional view of an example of an apparatus for applying lithium on the active material layer of the present invention Schematic cross-sectional view of an example of a conventional apparatus for applying lithium on an active material layer Schematic cross-sectional view of an example of a conventional apparatus for applying lithium on an active material layer Schematic cross-sectional view of an example of a conventional apparatus for applying lithium on an active material layer Schematic sectional view of an example of an apparatus for forming an active material layer used in the present invention Schematic sectional view of an example of an apparatus for forming an active material layer used in the present invention Schematic cross-sectional view of an example of a conventional apparatus for applying lithium on an active material layer (A) Schematic sectional view showing an example of a negative electrode shape after forming an active material layer used in the present invention, (b) Schematic sectional view showing another example Schematic cross-sectional view of a wound lithium secondary battery Schematic cross-sectional view of a stacked lithium secondary battery Diagram showing the dependency of capacity maintenance rate on the number of charge / discharge cycles The schematic sectional drawing which shows an example of the manufacturing method of the negative electrode for lithium secondary batteries used for this invention, (a) The figure which shows the state which prepared the electrical power collector, (b) The state after active material layer formation on an electrical power collector (C) The figure which shows the process of providing lithium on an active material Diagram showing conventional lithium application method

As shown in FIG. 14, the electrochemical device electrode plate manufacturing apparatus of the present invention is used in connection with a method for manufacturing a negative electrode for a lithium secondary battery having the following steps (a) to (c). It is common.
(A) A step of preparing the current collector 101.
(B) A step of forming, on the current collector 101, an active material layer 103 including an active material capable of occluding and releasing lithium and having a thick portion 105 and a thin portion 107.
(C) A step of applying lithium 113 by injecting lithium vapor 111 onto the active material from a plurality of directions inclined with respect to the normal line of the current collector 101.

  Here, the active material layer 103 includes a thick portion 105 and a thin portion 107. That is, a gap 109 is formed between the thick portion 105 and the adjacent thick portion 105. By adopting such a structure, even when the negative electrode absorbs lithium during charging and expands, the volume change can be reduced and the active material layer 103 can be prevented from being separated from the current collector 101. Note that the thin portion may have a film thickness of zero. That is, the active material layer 103 may not be a continuous film.

  The electrochemical element plate manufacturing apparatus of the present invention is used in step (c). In the step (c), the lithium vapor 111 enters the active material thin film 103 from a plurality of directions inclined from the normal direction 115 of the current collector 101. By entering from a direction inclined from the normal direction, lithium becomes difficult to adhere to the thin portion 107 of the active material thin film. This is the so-called self-shadowing effect. Therefore, more lithium adheres to the thick portion 105 of the active material thin film 103, and only a relatively small amount of lithium adheres to the thin portion of the active material thin film. Thereby, it is difficult for the thick portion of the active material thin film to be short of lithium. On the contrary, in the thin part, problems such as excessive lithium and dendrite precipitation hardly occur. Further, by entering from a plurality of directions, lithium can be more uniformly applied to the thick part of the active material. Therefore, the negative electrode of the present invention is excellent in cycle characteristics.

  In the step (c), lithium attached to the active material immediately reacts with the active material. Therefore, when the negative electrode is examined after the step (c), the lithium and the active material are not separated from each other (the state illustrated in FIG. 14C), and lithium is diffused in the active material.

In the step (c), the apparatus for applying lithium on the active material preferably has a semi-enclosed structure of lithium vapor. The semi-enclosed structure is a container that encloses a lithium evaporation source (film forming material) inside the vacuum layer, and a film forming nozzle (opening) is attached to this container, and lithium vapor is drawn from the opening. Means a structure attached to the active material layer. Furthermore, this nozzle has directivity. By this directivity, the incident direction of lithium vapor is controlled in a direction inclined with respect to the normal line of the current collector. This directivity control is easy to control with the current plate of the nozzle. By giving the nozzle directivity in a plurality of directions, the direction in which lithium vapor is incident on the active material can be a plurality of directions.

  A sheet-like metal foil containing copper, nickel, or the like can be used for the current collector in step (a). By using a current collector having a protrusion shape, the active material layer can be selectively formed as a starting point. Further, the presence of the protrusion shape on the current collector is advantageous in improving the adhesion strength. The material composition of the sheet portion and the protruding portion may be the same or different. The total thickness of the current collector is preferably 10 to 50 microns, more preferably 15 to 40 microns, from the viewpoints of strength, volumetric efficiency as a battery, and ease of handling.

  In the step (b), an active material layer is formed on one side or both sides of the current collector. The active material contained in the active material layer is not particularly limited as long as it is electrochemically reactive with lithium, but is relatively high in reactivity with lithium and can be expected to have a high capacity. Including at least one selected from the group consisting of a compound containing silicon and oxygen, a compound containing silicon and nitrogen, a simple substance of tin, a tin alloy, a compound containing tin and oxygen, and a compound containing tin and nitrogen It is preferable. It is because the improvement degree by this invention becomes remarkable.

  The average thickness of the active material layer varies depending on the performance of the battery to be manufactured, but is generally in the range of 3 to 40 microns. When the active material layer is less than 3 microns, the proportion of the active material in the entire battery decreases, and the energy density of the battery decreases. On the other hand, when the active material layer exceeds 40 microns, the stress at the interface between the current collector and the active material layer increases, and the current collector tends to be deformed.

From the viewpoint of reactivity with lithium, the active material layer is preferably amorphous or low crystalline. The term “low crystallinity” as used herein refers to a region where the crystal grain size is 50 nm or less. Note that the grain size of the crystal grains is calculated by the Scherrer equation from the half-value width of the peak with the highest intensity in the diffraction image obtained by X-ray diffraction analysis. Amorphous means having a broad peak in the range of 2θ = 15 to 40 ° in a diffraction image obtained by X-ray diffraction analysis.
The formation of the active material layer in the step (b) will be described in more detail below.

  FIG. 7 is a schematic view illustrating an example of a part of a manufacturing apparatus for forming an active material layer. In FIG. 7, the vacuum chamber 2 is exhausted by an exhaust pump 4. The substrate 21, which is a long current collector material unwound from the unwinding roll 8 in the vacuum chamber 2, is guided to the transport roller 5 and passes through the first opening and the second opening of the shielding plate 10. After traveling, the vehicle further travels through the third opening and the fourth opening of the shielding plate, and is taken up by the take-up roll 3. The substrate 21 used here is a sheet-like foil made of copper, nickel or the like. The active material application source 19 contains silicon or tin in a crucible or the like. The active material application source 19 is heated by a heating device (not shown) such as an electron beam, and silicon or tin evaporates.

When the substrate (current collector) 21 is exposed to silicon, tin, or the like flying from the active material application source 19 in the first opening and the second opening of the shielding plate 10, silicon is formed on one surface of the substrate 21. A first active material layer (not shown) made of tin or tin is formed. Next, the third surface and the fourth opening of the shielding plate 10 are exposed to silicon, tin, etc. flying from the substrate 21 active material application source 19, so that the other surface is made of silicon, tin, etc. Two active material layers (not shown) are formed. In this way, by forming the active material layer on the substrate having the protrusion shape by the oblique vapor deposition method, as shown schematically in FIG. The active material is selectively grown in a columnar shape on 25, and an active material layer having a space between the columnar active materials 22 can be formed. However, a slight film formation is also performed between the columnar particles and the lower active material 23 is formed so that the current collector is not exposed. The growth of the active material layer on the substrate 21 is performed when the first opening and the second opening, and both the third opening and the fourth opening are used for film formation. Since evaporated atoms are incident on the shape from two directions, an active material layer 24 having a columnar active material 22 as schematically shown in FIG. 10A is obtained. Further, when one of the first opening and the second opening and one of the third opening and the fourth opening are used for film formation, the evaporated atoms from one direction with respect to the protrusion shape of the substrate 21. For example, an active material layer 24 having a columnar active material 22 as schematically shown in FIG. 10B is obtained. The present invention is effective for both active material layers of FIG.

In addition, the columnar active material 22 of the active material layer 24 formed as described above corresponds to a thick portion of the active material layer, and the lower active material 23 corresponds to a thin portion.
The active material layer can also be formed by providing an opening portion of the shielding plate in a portion where the substrate travels along the peripheral surface of the cylindrical can. By providing the substrate in a portion where the substrate travels in a straight line, it is possible to efficiently use the obliquely incident component of the evaporated atoms on the substrate, so that the productivity of the active material layer having a space between the columnar active materials It is effective for improvement.

  In order to form an active material layer of a compound containing silicon and oxygen, a compound containing silicon and nitrogen, a compound containing tin and oxygen, or a compound containing tin and nitrogen, oxygen gas or nitrogen gas is used. Introducing from an introduction pipe (not shown) and evaporating silicon or tin from the active material application source 19 under these gas atmospheres, a work-in-process negative electrode before application of lithium is obtained. In the case of forming an active material containing nitrogen, it is particularly effective to secure the reaction efficiency by converting the introduced gas into plasma.

  Step (b) of the present invention may be any method that can form an active material layer 103 having a thick portion 105 and a thin portion 107 on the current collector 101 as shown in FIG. Although the specific process of the step (b) is not particularly limited, it is preferable to use a dry process such as a vapor deposition method, a sputtering method, or a CVD method.

After the formation of the active material layer (step (b)), as step (c), lithium is applied as a countermeasure for irreversible capacity, and the negative electrode is completed.
In the lithium ion battery of the present invention, the battery is constituted after lithium is applied to the negative electrode plate by a thin film process.

  As a result of intensive studies, we have found that the expansion of the negative electrode is caused by occlusion of lithium during charging, regardless of whether discharge is possible or not. Therefore, the negative electrode plate with the irreversible capacity countermeasure has an increase in thickness of 20%, for example, and further expands by storing more lithium during charging.

One of the main causes of the deterioration reaction of the negative electrode plate and the generation of lithium dendride is excessive lithium, avoiding excessive application when applying lithium, and applying lithium according to the film thickness in each part of the active material layer It is valid. Accordingly, it is desirable to selectively apply lithium to the columnar particle portion (thick portion). In conventional lithium application by a thin film process, lithium is almost uniformly distributed over the entire active material layer. Therefore, excess lithium is present in the thin portion between the columnar particles (thick portion) and the columnar particles (thin portion) of the active material layer. In some cases, the negative electrode plate deteriorates or the dendride grows in the worst case with repeated charging and discharging.
In order to prevent excessive lithium from being applied to the thin portion of the active material layer, an apparatus schematically shown in FIG. 4 can be used in step (c). In FIG. 4, the lithium supply source 18 holds the lithium material 16. The lithium supply source 18 has a semi-enclosed structure having an opening facing the substrate 21 on which an active material layer has been formed that travels in the vicinity. Here, the semi-sealed structure means that the lithium material is enclosed inside the vacuum chamber separately from the vacuum chamber 2. By making the lithium application source 18 in this semi-sealed structure, unnecessary scattering can be prevented, and lithium vapor can be used for applying lithium efficiently. The lithium application source 18 is heated by a heating mechanism (not shown). As the heating method, induction heating, resistance heating, and other various methods can be used. The lithium application source 18 heated by the heating mechanism is further heated after the lithium material 16 is dissolved and held in order to evaporate lithium corresponding to a predetermined lithium film formation rate. Lithium vapor generated by heating the lithium material 16 travels toward the surface of the active material layer of the substrate 21 that travels along the peripheral surfaces of the first can 6 and the second can 7.

At that time, as shown in FIG. 4, lithium is an active material layer by setting the normal direction of the substrate to an oblique direction with respect to a directivity direction that is a direction connecting lithium material openings held in a lithium application source. Incident on the surface from an oblique direction. When the active material layer is made of a columnar active material that grows obliquely from the substrate surface as shown in FIG. 10B, the incident direction of lithium is shifted from the growth direction of the columnar particles of the active material. It is necessary to keep. Thus, it is possible to avoid excessive application during the application of lithium and to apply lithium according to the film thickness in each part of the active material layer. However, since lithium is applied only from one direction of the columnar active material, the film formation rate is limited in order for lithium to occlude at the same time as film formation. Therefore, an apparatus schematically shown in FIG. It can be used in (c). In FIG. 5, the lithium supply source 18 holds the lithium material 16. The lithium supply source 18 has a semi-enclosed structure having an opening in the axial direction inclined with respect to the normal line of the substrate 21 on which the active material layer is formed that travels in the vicinity.

  The film forming nozzle is heated by a heating mechanism (not shown). Lithium vapor generated by heating the lithium material 16 is directed to the surface of the active material layer formed on the front and back surfaces of the substrate at the two locations of the first can and the two locations of the second can. In each can, lithium enters the surface of the active material layer from two oblique directions. By intermittently applying lithium from two directions, an increase in substrate temperature can be suppressed.

Another example of the method for applying lithium from a plurality of directions is schematically shown in FIG. As shown in FIG. 6, by using a plurality of film formation nozzles having different directivity control directions, lithium can be simultaneously applied to the active material from a plurality of incident directions. By applying lithium simultaneously from two directions, the reaction between the active material and lithium can be promoted more uniformly.
In the manufacturing apparatus schematically shown in FIGS. 5 and 6, since two film forming sources are used to apply lithium from two directions, a total of four components are used for applying lithium to the active material on the front and back surfaces. A membrane source is needed. Therefore, the apparatus configuration is complicated, the equipment cost is increased, and the heat insulation structure and control for equalizing the lithium application from two directions by eliminating the thermal interference between the lithium application sources are complicated.

  Therefore, an apparatus that can apply lithium to the active material layer from a plurality of directions by a simpler method is desirable.

On the other hand, FIG. 1 schematically shows an example of the lithium application device of the present invention used in the step (c) constituting a part of the manufacturing method of the electrode plate.
In FIG. 5, the lithium supply source 18 holds the lithium material 16. The lithium supply source 18 has a semi-enclosed structure having an opening facing the substrate 21 on which an active material layer has been formed that travels in the vicinity.

  The film forming nozzle is heated by a heating mechanism (not shown). Lithium vapor generated by heating the lithium material 16 moves along the rectifying plate 17 provided in the opening and travels toward the surface of the active material layer. At that time, by forming the vapor passage in two oblique directions opposite to the substrate normal, lithium is incident on the surface of the active material layer from two oblique directions.

  According to the method of FIG. 1, since lithium can be applied from two directions with one lithium application source, the apparatus configuration is simplified and the equipment cost can be reduced.

  In addition, by making the heating and conductance configuration of the lithium application source uniform with respect to the two directions of the lithium application, the amount of lithium applied in the two directions can be made almost equal. It is not necessary to design a structure for thermally separating the gaps, and the difficulty of control due to thermal interference can be avoided.

  The present invention is not limited to these examples, and other nozzle systems in which lithium is incident on the surface of the active material layer from a plurality of oblique directions can also be used.

  When lithium is incident on the surface of the active material layer from an oblique direction, most of the lithium adheres to the columnar active material in the active material layer without reacting between the columnar active material in the active material layer and reacts. . Accordingly, the amount of lithium flying between the columnar active material and the columnar active material in the active material layer is greatly reduced, and lithium can be applied according to the film thickness in each part of the active material layer.

The negative electrode 20 obtained by such a method includes a positive electrode plate containing a commonly used positive electrode active material such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , a separator made of a microporous film, and hexafluoride. A lithium secondary battery can be produced by using lithium phosphate or the like together with an electrolytic solution having lithium ion conductivity having a generally known composition in which cyclic carbonates such as ethylene carbonate and propylene carbonate are dissolved. At that time, it is preferable to make the width of the positive electrode plate slightly smaller than the width of the negative electrode plate for the purpose of preventing lithium from being deposited in the shape of the negative electrode plate during charging.

  In addition, the negative electrode of the present invention can be applied to lithium secondary batteries having various shapes, and the shape and sealing form of the battery are not particularly limited. However, the present invention is particularly applicable to a foldable or wound type secondary battery. It is effective. When applied to a wound lithium secondary battery, it is preferable to have the following configuration. This will be described with reference to the drawings.

  FIG. 11 is an example of a schematic cross-sectional view of a wound lithium secondary battery of the present invention. In FIG. 611, the strip-shaped positive electrode 31 and the strip-shaped negative electrode 20 of the present invention are wound together with a strip-shaped separator having a width wider than that of the two electrode plates, thereby forming the electrode plate group 32. . A positive electrode lead 34 made of aluminum or the like is connected to the positive electrode 31, and one end thereof is connected to a sealing plate 39 in which an insulating packing 40 made of polypropylene or the like is arranged at the periphery. A negative electrode lead 35 made of copper or the like is connected to the negative electrode 20, and one end thereof is connected to a battery can 38 that houses the electrode plate group 32. An upper insulating ring 36 and a lower insulating ring 37 are arranged above and below the electrode plate group 32, respectively. The electrode plate group 32 is impregnated with the above-described electrolyte (not shown) having lithium ion conductivity. The opening of the battery can 38 is closed with a sealing plate 39.

  Although the wound type battery has been described in the above embodiment, the effects of the present invention can be obtained for a sheet type and a stack type battery in which an electrode plate and a separator are repeatedly laminated. FIG. 12 is an example of a schematic cross-sectional view of a stack type (stacked type) battery of the present invention. In FIG. 12, the positive electrode 31 and the strip-shaped negative electrode 20 of the present invention are laminated so as to have a negative electrode portion not facing the positive electrode together with the separator 33 disposed between them to form an electrode plate group 32. Yes. In the electrode plate group 32, a positive electrode external electrode 41 and a negative electrode external electrode 42 are connected to the positive electrode and the negative electrode, respectively.

Next, the present invention will be described using more specific embodiments.
(Embodiment 1)
First, in step (a), the current collector is an alloy copper foil having a width of 85 mm and a thickness of 18 microns, and a plurality of frustoconical convex portions are formed in a staggered arrangement on both sides by machining. The height of each convex portion is 6 microns. Further, the bottom width of the convex portion in the long longitudinal section of the current collector is 20 microns, and the distance to the adjacent convex portion is 20 microns.

Next, as a step (b), a silicon thin film is formed on both sides of the current collector as an active material layer so as to have an average thickness of 8 microns by a vacuum deposition method using an apparatus as shown in FIG.
As a preparation for the step (b), a vacuum tank having a volume of 0.4 cubic meters and having two oil diffusion pumps having a diameter of 14 inches as the exhaust means 37 is once exhausted to 0.004 Pascal before film formation. Using a 270-degree deflection electron beam evaporation source manufactured by JEOL Ltd., an electron beam with an acceleration voltage of −10 kV and an average emission current of 680 mA is irradiated onto silicon, and the generated vapor is directed to the copper foil substrate.

  The shielding plate 10 (opening length is 20 cm each) is placed on the copper foil substrate close to a distance of about 2 mm so that the silicon thin film has a film formation width of 65 mm. The copper foil substrate transfer mechanism can reciprocate. When film formation is performed at a substrate transfer speed of 2.4 m / min and an average film formation speed of 100 nm / sec, a film thickness of 0. A silicon thin film of about 5 microns is formed one by one. By repeating the film formation 16 times while reciprocating, a silicon thin film of about 8 microns can be laminated. In addition, the substrate in the film formation region is cooled by a cooling mechanism including a cooling body 12 disposed close to the back surface of the film formation surface and an introduction pipe for introducing an appropriate amount of gas between the cooling body and the substrate.

  In this way, the active material layer formed on the current collector is used as a negative electrode.

  Next, as step (c), lithium application corresponding to irreversible capacity is performed. The irreversible capacity of the in-process negative electrode is examined by a charge / discharge test using the in-process negative electrode and a coin battery with lithium as the counter electrode, and it is found that the lithium equivalent to 1.2 microns is required. Lithium is applied by vacuum deposition of lithium using an apparatus similar to the apparatus shown in FIG. The vacuum chamber is once evacuated to 0.001 Pa before film formation. The degree of vacuum during film formation is 0.002 Pascal, and no gas is introduced.

  Using a nozzle-type film-forming source, the film-forming source is heated by a heater, and the work-in-process negative electrode is moved along a can cooled by 10 ° C. cooling water at a transfer speed of 0.8 m / min. Lithium is applied over a width of 60 mm in accordance with the silicon thin film formation position. The angle formed by the substrate normal at the center of the nozzle opening and the extension of the nozzle baffle is ± 30 degrees. Thereafter, both ends where the silicon thin film is not formed are cut at a position of 60 mm in width, and a negative electrode plate is formed by cutting at a position of 900 mm in length.

  The negative electrode plate and the aluminum foil as a current collector, LiCoO2 as an active material, an electrode lead is welded to a positive electrode with a width of 56 mm, a separator with a width of 62 mm is wound between the two electrode plates, wound into a cylindrical case, Electrolytic solution injection and sealing are performed to form a cylindrical battery. Details will be described below.

As the positive electrode active material LiCoO ₂ , Li ₂ CO ₃ and CoCO ₃ are mixed at a predetermined molar ratio, synthesized by heating at 950 ° C., and classified to a particle size of 45 microns or less. To 100 parts by weight of the positive electrode active material, add 5 parts by weight of acetylene black as a conductive agent, 4 parts by weight of polyvinylidene fluoride as a binder, and an appropriate amount of N-methyl-2-pyrrolidone as a dispersion medium, and mix well. A positive electrode mixture paste is obtained. The positive electrode mixture paste is applied to both sides of a current collector made of an aluminum foil having a thickness of 15 microns (manufactured by Showa Denko KK), dried and rolled. In this way, a positive electrode comprising a current collector and a positive electrode mixture layer carried on both sides thereof is obtained.

  One end of an aluminum positive electrode lead is connected to the positive electrode current collector. One end of a nickel negative electrode lead is connected to the negative electrode current collector. As the separator, a microporous film made of polyethylene resin having a thickness of 20 microns is used. As the electrolytic solution, a solution obtained by dissolving lithium hexafluorophosphate at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1 is used.

  The electrode plate group constituted by winding is vacuum-dried at 60 ° C. for 10 hours in a dry atmosphere having a dew point of −60 ° C. to expel moisture contained in the electrode group. Insulating rings are arranged above and below the electrode plate group and accommodated in the battery can. Next, the nonaqueous electrolyte is poured into the battery can and impregnated in the electrode plate group. The other end of the positive electrode lead is welded to the back surface of the positive electrode terminal at the center of the insulating sealing plate. The other end of the negative electrode lead was welded to the inner bottom surface of the battery can. Finally, the opening of the battery can is closed with a sealing plate. In this way, a cylindrical lithium ion secondary battery is completed.

(Embodiment 2)
As the current collector, a plurality of elliptical truncated cone-shaped convex portions are formed in a staggered arrangement by machining on both sides of an alloy copper foil having a width of 85 mm and a thickness of 18 microns, and the height of each convex portion is Prepare one that is 6 microns. Moreover, the bottom part width | variety in the longitudinal direction cross section of a long electrical power collector shall be 20 microns, and the space | interval to an adjacent convex part shall be 20 microns.
A silicon oxide thin film having a thickness of 15 microns is formed on both sides of the current collector by a vacuum deposition method using an apparatus as shown in FIG.

  After evacuating a vacuum chamber having a volume of 0.4 cubic meter having two oil diffusion pumps having a diameter of 14 inches as the exhaust means 37 to 0.002 Pascal, silicon which is a film forming material of the negative electrode active material is dissolved. Dissolution of silicon is performed using a 270-degree deflection electron beam evaporation source manufactured by JEOL. An electron beam with an acceleration voltage of −10 kV and an average emission current of 930 mA is irradiated onto the molten silicon, and the generated vapor is directed to the copper foil substrate.

  The shielding plate 10 (opening length is 15 cm each) is placed on the copper foil substrate in the vicinity of a distance of about 2 mm so that the film width of the silicon oxide thin film becomes 65 mm. In addition, oxygen gas is directed to the opening of the shielding plate from a reaction gas nozzle (not shown) installed on the film forming surface side of the copper foil substrate, and 30 sccm is directed to each opening. As a result, a silicon oxide thin film is formed on the copper foil substrate. The copper foil substrate transfer mechanism can reciprocate. When film formation is performed at a substrate transfer speed of 3.6 m / min and an average film formation speed of 200 nm / sec, the film thickness is 1 micron on both sides of the substrate in a single run. A silicon oxide thin film of a degree is formed one by one. By repeating the film formation 15 times while reciprocating, a silicon oxide thin film of about 15 microns can be laminated. Further, the substrate in the film formation region is cooled by a cooling mechanism including a cooling body arranged close to the back surface of the film formation surface and an introduction pipe for introducing an appropriate amount of gas between the cooling body and the substrate.

  This formed as described above is used as a working negative electrode.

Next, lithium corresponding to an irreversible capacity is applied. Using the in-process negative electrode, the irreversible capacity of the in-process negative electrode was examined by a charge / discharge test using a coin battery with lithium as a counter electrode. As a result, it was found that the application corresponding to the lithium thickness of 8 microns is necessary. Lithium is applied by vacuum deposition of lithium using an apparatus similar to the apparatus shown in FIG. The vacuum chamber is once evacuated to 0.001 Pa before film formation. The degree of vacuum in the vacuum chamber during film formation is 0.002 Pascal, and no gas is introduced. Using a nozzle-type film-forming source, the film-forming source is heated by a heater, and the in-process negative electrode is moved at a conveying speed of 0.12 m / min along the endless zone cooled by 10 ° C. cooling water. Lithium is applied over a width of 60 mm in accordance with the silicon oxide thin film formation position of the hanging negative electrode. The distance from the closest part of the endless belt to the tip of the nozzle opening is 5 mm, and the angle between the substrate normal and the nozzle rectifying plate is ± 45 degrees. Thereafter, both ends where the silicon oxide thin film is not formed are cut at a position having a width of 60 mm, and cut at a position having a length of 900 mm to obtain a negative electrode plate.

  The negative electrode plate and the aluminum foil as a current collector, LiCoO2 as an active material, an electrode lead is welded to a positive electrode with a width of 56 mm, a separator with a width of 62 mm is wound between the two electrode plates, wound into a cylindrical case, The electrolytic solution is poured and sealed, and a cylindrical lithium ion secondary battery is formed in the same manner as in the first embodiment.

(Embodiment 3)
In the same manner as the in-process negative electrode forming method in the first embodiment, an in-process negative electrode having a thickness of 8 microns is formed on each side of the current collector.

  Next, lithium corresponding to an irreversible capacity is applied. Using the in-process negative electrode, the irreversible capacity of the in-process negative electrode was examined by a charge / discharge test using a coin battery with lithium as a counter electrode. As a result, it was found that the lithium equivalent to 1.2 microns was necessary. Lithium is applied by means of vacuum deposition of lithium using an apparatus similar to the apparatus shown in FIG. The vacuum chamber is once evacuated to 0.001 Pa before film formation. The degree of vacuum during film formation is 0.002 Pascal, and no gas is introduced.

  Using a nozzle-type film-forming source, the film-forming source is heated by a heater, an in-process negative electrode is moved at a conveyance speed of 0.8 m / min along a can cooled by cooling water at 10 ° C., and an adhesion speed of 80 nm. Lithium is applied over a width of 60 mm in accordance with the silicon thin film formation position of the in-process negative electrode at / second. The direction of the nozzle rectifying plate is the vertical direction, the interval between the rectifying plates is 2 cm, and the total opening length of the nozzles in the substrate running direction is 20 cm. Thereafter, both ends where the silicon thin film is not formed are cut at a position of 60 mm in width, and a negative electrode plate is formed by cutting at a position of 900 mm in length.

The negative electrode plate and the aluminum foil as a current collector, LiCoO2 as an active material, an electrode lead is welded to a positive electrode with a width of 56 mm, a separator with a width of 62 mm is wound between the two electrode plates, wound into a cylindrical case, The electrolytic solution is poured and sealed, and a cylindrical lithium ion secondary battery is formed in the same manner as in the first embodiment.
(Comparative form 1)
An in-process negative electrode is formed in the same manner as in the first embodiment. Next, lithium corresponding to an irreversible capacity is applied. Lithium is applied by vacuum deposition of lithium using an apparatus schematically shown in FIG. The vacuum chamber is once evacuated to 0.001 Pa before film formation. The degree of vacuum during film formation is 0.002 Pascal, and no gas is introduced. Using a resistance heating evaporation source, the evaporation source is heated by a heater, and the in-process negative electrode is moved along the can at a transfer speed of 1.2 m / min, while the deposition speed is 120 nm / sec. Lithium is applied over a width of 60 mm using a shielding plate 10 (opening length is 20 cm) aligned with the center of the width. Thereafter, both ends where the silicon thin film is not formed are cut at a position of 60 mm in width, and a negative electrode plate is formed by cutting at a position of 900 mm in length.

  Using the negative electrode plate, a cylindrical lithium ion secondary battery is formed by the same method as in the first embodiment.

Elemental analysis in the negative electrode is performed by wavelength dispersive X-ray spectroscopy (hereinafter referred to as WDS). When a cut surface perpendicular to the substrate is provided and characteristic X-ray analysis is performed, a considerable amount of lithium is detected even in a portion where the active material film thickness is small between the columnar particles in the electrode plate of Comparative Example 1. However, in the electrode plates of Embodiments 1 to 3, the lithium detection between the columnar particles and the columnar particles (thin portion of the active material layer) is less than that of Comparative Embodiment 1, and the lithium application is performed in the columnar particle portion (active portion). It can be seen that this is selectively performed on a thick portion of the material layer.

Next, the present invention will be described using more specific examples.
Example 1
As the current collector, a plurality of elliptical truncated cone-shaped convex portions are formed in a staggered arrangement by machining on both sides of an alloy copper foil having a width of 85 mm and a thickness of 18 microns, and the height of each convex portion is What was 6 microns was prepared. Further, the bottom width of the protrusions in the longitudinal section of the long current collector was 20 microns, and the distance to the adjacent protrusions was 20 microns.

  Next, a silicon oxide thin film having a thickness of 15 microns was formed on both surfaces of the current collector by a vacuum deposition method using an apparatus as shown in FIG.

  After evacuating a vacuum chamber having a volume of 0.4 cubic meter equipped with two oil diffusion pumps having a diameter of 14 inches as the exhaust means 37 to 0.002 Pascal, silicon as a film forming material for the negative electrode active material was dissolved. Dissolution of silicon was performed using a 270-degree deflection electron beam evaporation source manufactured by JEOL. An electron beam with an acceleration voltage of −10 kV and an average emission current of 930 mA was irradiated onto the molten silicon, and the generated vapor was directed to the copper foil substrate.

  The shielding plate 10 (opening length was 15 cm each) was placed on the copper foil substrate in the vicinity of a distance of about 2 mm so that the film formation width of the silicon oxide thin film was 65 mm. In addition, oxygen gas was directed to the opening of the shielding plate from a reaction gas nozzle (not shown) installed on the film forming surface side of the copper foil substrate, and 30 sccm was directed to each opening. As a result, a silicon oxide thin film was formed on the copper foil substrate. The copper foil substrate transfer mechanism can reciprocate. When film formation is performed at a substrate transfer speed of 3.6 m / min and an average film formation speed of 200 nm / sec, the film thickness is 1 micron on both sides of the substrate in a single run. About one silicon oxide thin film was formed layer by layer. By repeating the film formation 15 times while reciprocating, a silicon oxide thin film of about 15 microns could be laminated. The substrate in the film formation region is cooled by a cooling mechanism including a cooling body arranged close to the back surface of the film formation surface and an introduction pipe for introducing an appropriate amount of gas between the cooling body and the substrate.

  A negative electrode was prepared by forming an active material thin film layer on the current collector thus prepared.

  Next, lithium corresponding to an irreversible capacity is applied. The irreversible capacity of the in-process negative electrode is examined by a charge / discharge test using the in-process negative electrode and a coin battery using lithium as a counter electrode, and it is found that the lithium equivalent to 8 microns is required. Lithium was applied by vacuum deposition of lithium using the apparatus schematically shown in FIG. The vacuum chamber was once evacuated to 0.001 Pa before film formation. The degree of vacuum in the vacuum chamber during film formation is 0.002 Pascal, and no gas is introduced. Using a nozzle-type film-forming source, the film-forming source is heated by a heater, an in-process negative electrode is moved at a conveying speed of 0.12 m / min along a can cooled by cooling water at 10 ° C., and an adhesion speed of 160 nm. / Sec., Lithium was applied over a width of 60 mm in accordance with the silicon oxide thin film formation position of the in-process negative electrode. The total opening length of the nozzles in the substrate running direction is 10 cm. Thereafter, both ends including a portion where the silicon oxide thin film was not formed were cut at a position having a width of 15 mm, and cut at a position having a length of 15 mm to obtain a negative electrode plate.

The negative electrode plate and aluminum foil as a current collector, LiCoO ₂ as an active material, an electrode lead is welded to a positive electrode having a width of 15 mm, and a separator having a width of 17 mm is placed between the two electrode plates and placed in a laminate case. Were injected and sealed to form a stamp-type lithium ion secondary battery.

(Comparative Example 1)
An in-process negative electrode was formed in the same manner as in Example 1.

Next, lithium application corresponding to irreversible capacity was performed. Lithium was applied by vacuum deposition of lithium using an apparatus schematically shown in FIG. The vacuum chamber was once evacuated to 0.001 Pa before film formation. The degree of vacuum during film formation is 0.002 Pascal, and no gas is introduced. Using a resistance heating evaporation source, heating the evaporation source with a heater, moving the negative electrode along the can and moving the negative electrode at a conveyance speed of 0.12 m / min, applying lithium over a width of 60 mm at an adhesion speed of 80 nm / sec It was. Thereafter, both ends including a portion where the silicon oxide thin film was not formed were cut at a position having a width of 15 mm, and cut at a position having a length of 15 mm to obtain a negative electrode plate.
A stamp-type lithium ion secondary battery was formed in the same manner as in Example 1 using the negative electrode plate.

  Next, charge / discharge cycle tests were performed on the lithium ion secondary batteries of Example 1 and Comparative Example 1 created as described above.

  The charge / discharge cycle test was performed in a constant temperature bath set at 20 ° C., with a charge current of 1C (1C is a one hour rate current) until the battery voltage reached 4.05V, and then at a current value of 4.05V. The battery was charged at a constant voltage until the battery voltage became 0.05 C, and then the operation of discharging the battery voltage to 2.5 V with a current of 1 C was repeated 100 cycles.

  As shown in FIG. 13, the battery formed by the method of Example 1 had a higher capacity retention rate than the battery formed by the method of Comparative Example 1. The reason for the superiority or inferiority of the charge / discharge cycle test is not clear enough, but in the comparative example, the amount of lithium with respect to the active material differs between the columnar particles and between the columnar particles, so the charge / discharge cycle deterioration due to non-uniformity occurs. I think that. Note that the present invention is not limited to the above-described examples, and is effective for forming an active material layer having a columnar particle structure by a method other than the examples, or for selectively applying lithium to the columnar particle portions. is there.

As a method for forming an active material layer having a thick portion and a thin portion, in addition to the formation method described in the above embodiment, a thin-film active material layer on a current collector, which is mentioned in JP-A-2003-303586, is cited. There is a method of forming a columnar shape by etching after forming.
In addition, the active material layer of the in-process negative electrode is not necessarily formed at a portion where the substrate travels linearly. For example, the active material layer can be formed while the substrate travels along a cooling can.

  Further, in the examples, the case where silicon and silicon oxide are used as the active material has been described, but the present invention is not limited to these active material materials, an alloy containing silicon, a compound containing silicon and oxygen, It is also effective for compounds containing silicon and nitrogen, tin alone, tin alloys, compounds containing tin and oxygen, compounds containing tin and nitrogen, and the like.

According to the electrochemical device electrode plate manufacturing apparatus of the present invention, lithium can be uniformly applied according to the amount of active material, so that the reliability of the battery is improved and it is useful as a lithium ion secondary battery.

DESCRIPTION OF SYMBOLS 2 Vacuum tank 3 Winding roll 4 Exhaust pump 5 Conveying roller 6 1st can 7 2nd can 8 Unwinding roll 9 Opening part 10 Shielding plate 11 Endless belt 12 Cooling body 13 3rd can 14 4th can 15 Cooling can 16 Lithium material 17 Current plate 18 Lithium source 19 Active material source 20 Negative electrode 21 Substrate 22 Columnar active material 23 Lower active material 24 Active material layer 25 Projection 31 Positive electrode 32 Electrode plate group 33 Separator 34 Positive electrode lead 35 Negative electrode lead 36 Upper insulating ring 37 Lower insulating ring 38 Battery can 39 Sealing plate 40 Insulating packing 41 Positive electrode external electrode 42 Negative electrode external electrode 43 Auxiliary material

Claims (4)

A transport system disposed in a vacuum chamber that is depressurized by an exhaust pump, and transports a substrate;
A material application source for holding a film forming material in a semi-enclosed structure disposed in the vicinity of the substrate and having an opening for applying material vapor to the substrate;
A heating source for heating the application source;
A slit structure disposed in the vicinity of the opening surface of the application source and imparting directivity to the material vapor,
The slit structure is a structure in which the incident direction of the material vapor directed toward the substrate is reversed with the substrate normal line as the substrate is transported in the film formation region. Membrane device.   2. The electrochemical element film forming apparatus according to claim 1, wherein an opening surface of the application source is disposed close to the substrate, and an application width of the material is regulated by an opening width of the application source. The substrate has an active material layer that absorbs and releases lithium, and a current collector,
The electrochemical element film forming apparatus according to claim 1, wherein the active material layer has a thick portion and a thin portion. The film forming apparatus for an electrochemical element according to claim 1, wherein the film forming material is Li.

Images