JP5148902B2 - All-solid-state lithium secondary battery manufacturing method and all-solid-state lithium secondary battery - Google Patents

Description

  The present invention relates to an all-solid lithium secondary battery manufacturing method and an all-solid lithium secondary battery.

  Conventionally, lithium ion secondary batteries are smaller than other secondary batteries such as nickel cadmium secondary batteries and nickel metal hydride secondary batteries because they have higher energy density and excellent charge / discharge cycle characteristics. It is widely used as a power source for mobile electronic devices such as mobile phones, notebook personal computers, and portable music players that are becoming thinner and thinner.

  However, in the current lithium ion secondary battery using a flammable organic electrolyte, in order to prevent leakage of the organic electrolyte, it is necessary to use a strong battery housing or aluminum laminate outer body, There is a limit to making the battery thinner. For this reason, it is very difficult to mount the present lithium ion secondary battery on a paper electronic display or an ultra-thin RF-RF (Radio frequency identification) tag that is expected to become popular in the future. .

  For this reason, a solid positive electrode film, a solid electrolyte film, and a solid negative electrode film are formed on a substrate by using a thin film manufacturing technique (a dry process such as a sputtering method or a vacuum deposition method or a wet process such as a sol-gel method). Attempts have been made to produce an all-solid-state secondary battery that can be used in a wide temperature range without being laminated and having a problem of leakage. For example, instead of quartz or silicon wafers commonly used as substrates, polymer films are used as substrates, and solid positive electrode films, solid electrolyte membranes, and solid negative electrode films are stacked on the films by thin film fabrication technology. If it is possible to manufacture a flexible battery that can be bent, the application to paper electronic displays and RF-ID tags is expected to expand.

To date, many reports have been made on all-solid-state lithium secondary batteries. For example, in Non-Patent Document 1, a positive electrode made of LiCoO ₂ is formed by RF (radio frequency) sputtering and heat-treated in an electric furnace, and then LiPON (Li ₃ PO _4-x N _x ), lithium metal as the negative electrode film, and laminated by using RF sputtering and vacuum deposition, respectively, to produce an all-solid-state thin film battery, energy density of about 0.8 mWh / cm ² and good charge / discharge cycle Has achieved the characteristics.

In Patent Document 1, an all solid-state secondary layer is formed by laminating a LiMn ₂ O ₄ positive electrode film, a Li ₂ OV ₂ O ₅ —SiO ₂ solid electrolyte film, and a metal negative electrode film such as lithium on a conductive substrate. A battery is manufactured, and good battery performance is realized with a small decay of discharge capacity even in a charge / discharge cycle of about 200 times.

  In Patent Document 2, a plurality of units of an all-solid-state secondary battery having a positive electrode film, a solid electrolyte film, and a negative electrode film as one unit are manufactured on the same substrate. Thus, a compact and high-capacity battery is realized by stacking multiple layers in series or in parallel.

J. B. Bates, et al., `` Preferred Orientation of Polycrystalline LiCoO2 Films. '', Journal of The Electrochemical Society, Vol. 147, No. 1, pp59-70, 2000 Japanese Patent Laid-Open No. 10-83838 Japanese Patent No. 3531866

  By the way, in the above-described conventional technique, when the positive electrode film, the solid electrolyte film, and the negative electrode film are laminated, the positive electrode film and the negative electrode film come into contact with each other, so that a short circuit may be caused. There was a problem that it was a manufacturing method of a possible all-solid-state lithium secondary battery.

  Here, the above-described conventional technology replaces the mask used for forming the positive electrode film, the solid electrolyte film, and the negative electrode film in an arbitrary two-dimensional shape for each stacking process, and thus the all solid-state lithium secondary battery. Manufacturing. Thus, by forming a solid electrolyte film having a large area so as to cover the positive electrode film or the negative electrode film, the positive electrode film and the negative electrode film are separated from each other, and a short circuit caused by contact between the positive electrode film and the negative electrode film is prevented. To prevent. For example, as shown in the region surrounded by the broken line on the right side of FIG. 9, the battery edge is in an orderly laminated structure so that the positive electrode film is completely covered with the solid electrolyte film and isolated from the negative electrode film. If so, a short circuit cannot occur. In addition, FIG. 9 is a figure for demonstrating the problem of a prior art.

  However, when the positive electrode film is laminated on the positive electrode collector film formed on the substrate and the solid electrolyte film having a larger area than the positive electrode film and the negative electrode film is laminated as described above, the broken line on the left side of FIG. As shown by the region surrounded by, the solid electrolyte membrane is formed so as to wrap around the edge surface of the positive electrode film in the region where there is a step in the battery edge portion, and the solid electrolyte film or the negative electrode film is formed at the battery edge portion. Since the thickness is reduced, there are many cases where a short circuit is caused, and there is a problem that this is a method for manufacturing an all-solid-state lithium secondary battery in which a defective product may occur.

  In addition, in order to increase the effective area of the battery, if the negative electrode film is laminated on the solid electrolyte film so as to have the same area as the positive electrode film laminated on the positive electrode collector electrode, the film thickness of the solid electrolyte film is reduced at the battery edge. Since the thinning may cause a short circuit, there is a problem in that it is a method for manufacturing an all-solid-state lithium secondary battery in which a defective product may occur.

  As described above, in the conventional technique described above, a short circuit is caused, the voltage becomes zero, and even if the voltage is displayed or the battery is charged / discharged by a soft short, the battery does not operate, and a defective product is generated. There is a problem in that it is a method of manufacturing an all solid lithium secondary battery that may occur.

  In addition, as shown in FIG. 9, in the case where an all-solid-type lithium secondary battery is manufactured by laminating a positive electrode collector electrode, a positive electrode film, a solid electrolyte membrane, a negative electrode film, and a negative electrode collector electrode in this order on the substrate, Although we explained that there were problems, even when manufacturing an all-solid-state lithium secondary battery by laminating a negative electrode collector electrode, a negative electrode film, a solid electrolyte film, a positive electrode film, and a positive electrode collector electrode in this order on the substrate. There was a similar problem.

  In addition, the above-described technology for multi-layer stacking of all-solid-state secondary batteries composed of multiple units in series or in parallel is expected to cause more short-circuits, and all-solid-state types that may cause defective products. There was a problem that it was a manufacturing method of a lithium secondary battery.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and provides an all-solid-state lithium secondary battery manufacturing method and an all-solid-type lithium secondary battery with a low incidence of defective products. For the purpose.

In order to solve the above-described problems and achieve the object, the present invention provides a solid electrolyte membrane made of a lithium ion conductive solid, a positive electrode membrane made of a solid capable of inserting and removing lithium ions, and lithium metal or An all-solid-state lithium secondary battery manufacturing method for manufacturing an all-solid-type lithium secondary battery having a configuration in which a negative electrode film made of a solid capable of occluding and releasing lithium ions is sandwiched and laminated. Of the collector electrode that contacts each of the membrane and the negative electrode membrane, the collector electrode that also contacts the substrate on which the all-solid-state lithium secondary battery is manufactured, on the other surface facing the surface that contacts the substrate, A collector electrode film forming step of forming a film so as to have at least one concave depression, and the concave depression of the collector electrode formed by the collector electrode film forming process Oite, wherein when stacking the positive electrode film or an electrode film serving as the negative electrode membrane, and the height of the surface on which the peripheral edge of the recess of the concave in which the collecting electrode has to contact the solid electrolyte membrane, the electrode film The electrode is formed such that a step that is different from the height of the surface in contact with the solid electrolyte membrane is 20% or less of the thickness of the solid electrolyte membrane, and is surrounded by the collector electrode. An electrode film forming step for forming a film; a peripheral portion of the concave depression of the collector electrode formed by the collector electrode forming step; and the electrode formed by the electrode film forming step. And a solid electrolyte membrane forming step of forming the solid electrolyte membrane so that the surface of the membrane is continuously coated.

Further, the present invention is the above invention, wherein, when the collector electrode film forming step is viewed from the center of the opening of the concave recess of the collector electrode, the bottom surface and the side surface of the concave recess have the concave shape. The collector electrode is formed so as not to be shielded by the periphery of the opening of the depression.

Further, the present invention is characterized in that, in the above invention, the method further includes a positive electrode film forming step of forming a transition metal oxide containing at least one of Co, Ni 2, Mn, and V as the positive electrode film. To do.

Further, the present invention is the above invention, wherein the collector electrode film forming step is performed at a constant distance from the deepest portion of the sidewall portion or the opening portion of the recessed recess in the sidewall portion excluding the bottom surface portion of the recessed recess. The collector electrode is formed such that the surface from the depth portion to the opening of the concave recess is formed of an insulating material.

In the present invention, the positive electrode film, the negative electrode film, the solid electrolyte film, the collector electrode in contact with the positive electrode film, and the collector electrode in contact with the negative electrode film are each exposed to the outside air. It further includes a protective layer coating step of coating the surface with a protective layer made of an insulating material.

Further, the present invention is characterized by an all-solid-state lithium secondary battery manufactured by the all-solid-state lithium secondary battery production method according to any one of the above inventions of.

According to the present invention, of the collector electrodes that are in contact with each of the positive electrode film and the negative electrode film, the collector electrode that also contacts the substrate on which the all-solid-state lithium secondary battery is manufactured is opposed to the surface in contact with the substrate. On one surface, the collector electrode is formed so as to have at least one concave recess, and when the electrode film as the positive electrode film or the negative electrode film is laminated in the concave recess of the collector electrode to be formed, the collector electrode peripheral edge of the concave recesses and the height of the surface in contact with the solid electrolyte membrane having height and are different occurs stepped surface on which the electrode film is in contact with the solid electrolyte membrane, 20% of the thickness of the solid electrolyte membrane The electrode film is formed so that the entire periphery is surrounded by the collector electrode, and the peripheral edge of the concave depression of the collector electrode to be formed, and the surface of the electrode film to be formed And solid electrolytic so that it is continuously coated Since the formation of the film, it is possible to avoid the short circuit of the battery edge portion, it is possible to lower the incidence of defective products. In addition, this makes it possible to reduce the effective area of the battery by forming an electrode film formed on the solid electrolyte so as to have a smaller area than the solid electrolyte in order to avoid short circuit at the battery edge. As a result, the inefficiency of batteries can be reduced, resulting in the solution to the inefficiency of batteries, which makes it possible to easily produce efficient, all-solid-state lithium secondary batteries with high energy density. Become.

Further, according to the present invention, the solid electrolyte membrane is formed such that the peripheral edge of the concave depression of the collector electrode to be formed and the surface of the electrode film to be formed are continuously coated. Therefore, the collector electrode and the electrode film produced on the substrate can be densely coated with the solid electrolyte film to further avoid the short circuit at the battery edge, and the generation rate of defective products can be further reduced. become. That is, defects such as local non-uniformity in the thickness of the solid electrolyte membrane due to the step between the electrode membrane and the collector electrode can be prevented, and a short circuit at the battery edge can be further avoided, resulting in the generation of defective products. The rate can be made lower.

In addition, according to the present invention, when viewed from the center of the opening of the concave depression of the collector electrode, the bottom and side surfaces of the concave depression are not shielded by the peripheral portion of the opening of the concave depression. Since the collector electrode is formed, the electrode film can be densely and uniformly laminated in the concave depression of the collector electrode to further avoid a short circuit at the battery edge portion, thereby further reducing the incidence of defective products. It becomes possible.

In addition, according to the present invention, since the transition metal oxide containing at least one of Co, Ni 2, Mn, and V is formed as the positive electrode film, it is determined from the crystal structure and the valence state of the transition metal ion in the crystal. Thus, a positive electrode film can be manufactured using a material that can smoothly insert and desorb lithium ions, and a more efficient all-solid-state lithium secondary battery with high energy density can be manufactured. become.

Further, according to the present invention, in the side wall part excluding the bottom part of the concave depression, the opening of the concave depression from the deepest part of the side wall part or a part of a certain depth from the opening part of the concave depression. Since the collector electrode is deposited so that the surface up to the surface is made of an insulating material, a short circuit between the collector electrode fabricated on the substrate and the electrode membrane fabricated on the solid electrolyte membrane is avoided. It is possible to reduce the incidence of defective products.

According to the present invention, the positive electrode film, the negative electrode film, the solid electrolyte film, the collector electrode that is in contact with the positive electrode film, and the collector electrode that is in contact with the negative electrode film are each made of a protective material made of an insulating material. Since it coats with a layer, the battery excellent in stability and handling nature can be manufactured, and it becomes possible to make the incidence rate of inferior goods lower.

  Embodiments of an all solid lithium secondary battery manufacturing method and an all solid lithium secondary battery according to the present invention will be described below in detail with reference to the accompanying drawings. In the following description, after describing the all-solid-state lithium secondary battery manufacturing method according to Example 1 and the characteristics of the all-solid-state lithium secondary battery, all-solid-state lithium according to Example 2 is described as in Example 1. The characteristics of the secondary battery manufacturing method and the all-solid-state lithium secondary battery will be described. Further, the usefulness of the protective layer of the all-solid-type lithium secondary battery according to Example 1 will be described in Comparative Example 1, and finally The usefulness of the all solid lithium secondary battery according to Example 1 will be described in Comparative Example 2 between the all solid lithium secondary battery according to Example 1 and the all solid lithium secondary battery according to the related art. .

[Method for Producing All Solid-Type Lithium Secondary Battery in Example 1]
First, the outline and main features of the all-solid-state lithium secondary battery manufacturing method in Example 1 will be specifically described with reference to FIGS. 1 and 2. FIG. 1 is a bird's-eye view and a cross-sectional view for explaining the configuration of the all-solid-state lithium secondary battery in Example 1. FIG. 2 shows the positive electrode collector electrode of the all-solid-type lithium secondary battery in Example 1. It is sectional drawing for demonstrating the process from film-forming to film-forming of a positive electrode film.

  The all-solid-state lithium secondary battery in Example 1 has a solid electrolyte membrane made of lithium ion conductive solid, a positive electrode membrane made of solid capable of inserting and removing lithium ions, and occlusion of lithium metal or lithium ions. The main feature is that it can be manufactured by a manufacturing method with a low occurrence rate of defective products.

  This main feature will be briefly described. As shown in FIG. 1, first, a positive electrode collector electrode 2 having a concave depression is formed at the center on a quartz substrate 1 (15 mm × 15 mm, thickness 0.3 mm). Make it.

  Specifically, the positive electrode collector electrode 2 having a concave depression is produced by the steps shown in FIGS. First, as shown in FIG. 2A, the first mask 8 is set at the center of the substrate 1. Here, the first mask 8 is a mask having a thickness of 50 μm and has an opening in which a square (10 mm × 10 mm) and a rectangle (2 mm × 4 mm) are combined (the positive electrode collector electrode 2 in the overhead view of FIG. 1). See shape). Note that the opening in the rectangular (2 mm × 4 mm) portion is used to form the positive electrode terminal in the positive electrode collector electrode 2.

Subsequently, as shown in FIG. 2B, the substrate 1 on which the first mask 8 is set is placed in an RF magnetron sputtering apparatus and depressurized to the order of 10 ⁻⁵ Pa. 0.0 Pa), a Pt target is used, an RF output is 100 W, and Pt (platinum) is deposited so that the film thickness becomes 0.5 μm. By removing the first mask 8 from this state, the lower structure of the positive electrode collector electrode 2 is obtained as shown in FIG.

  Then, as shown in FIG. 2D, a second mask 9 (opening: 7 mm × 7 mm, thickness: 50 μm) is placed at the center of the lower structure of the obtained positive electrode collector electrode 2. The third mask 10 (opening: 10 mm × 10 mm, thickness: about 50 μm) is set so as to be in contact with the lower structure 2 and to shield the portion where the battery material is not deposited on the substrate 1. , Set on the substrate 1.

  After that, as shown in FIG. 2E, Pt (platinum) is sputtered to a thickness of 0.5 μm under the same conditions as in FIG. Is made. By removing the second mask 9 and the third mask 10 from this state, as shown in FIG. 2F, the upper structure of the positive electrode collector electrode 2 is obtained, and the substrate 1 has a concave depression. A positive electrode collector electrode 2 is prepared.

  As described above, when viewed from the center of the opening of the concave depression of the positive electrode collecting electrode 2 by the steps shown in FIGS. 2A to 2E, the bottom and side surfaces of the concave depression are concave. The positive electrode collector electrode 2 is prepared so as to have a structure that is not shielded by the periphery of the opening of the depression.

  Subsequently, as shown in FIG. 2G, the fourth mask 11 (opening: 7 mm × 7 mm, thickness: 50 μm) is set so as to cover and contact the upper structure of the positive electrode collector electrode 2.

Then, as shown in FIG. 2H, the film formation time is adjusted so that the film thickness is 0.5 μm in the concave depression of the positive electrode collector electrode 2, and lithium cobalt oxide (LiCoO ₂ ) is used. A positive electrode film 3 is produced. Here, the step between the surface where the peripheral edge of the concave depression of the positive electrode collecting electrode 2 contacts the solid electrolyte membrane 4 described later and the surface where the positive electrode film 3 contacts the solid electrolyte membrane 4 described later is reduced. In other words, the positive electrode film 3 is produced so that the film thickness becomes a value close to 0.5 μm.

Specifically, the positive electrode film 3 made of lithium cobalt oxide (LiCoO ₂ ) is formed by an electron cyclotron resonance (ECR) sputtering method using a lithium cobalt oxide ceramic target and a distribution of argon and oxygen. The pressure ratio was set to 40: 1, the total gas pressure was set to 0.14 Pa, and the microwave output and RF output were set to 800 W and 500 W, respectively. Note that the LiCoO ₂ positive electrode film produced under these conditions was confirmed to have high crystallinity even without heat treatment in an electric furnace by an X-ray diffraction method or the like.

  Here, as described above, the step between the surface where the peripheral edge of the concave depression of the positive electrode collector electrode 2 is in contact with the solid electrolyte membrane 4 described later and the surface where the positive electrode membrane 3 is in contact with the solid electrolyte membrane 4. The positive electrode film 3 is formed so as to be smaller, but the step is 20% or less of the thickness (1 μm in this embodiment) of the solid electrolyte film 4 produced in the next stage (this embodiment) In the example, 0.2 μm or less is desirable in order to reduce the incidence of defective batteries. This will be described in detail later.

  Note that the positive electrode film 3 formed under the above conditions is slightly lower than the peripheral edge of the concave depression of the positive electrode collector electrode 2, and as a result of precise observation with a scanning electron microscope (SEM), the level difference is 0. .18 μm. Further, when a negative electrode collector electrode having a concave depression is produced on the substrate 1 and a negative electrode film is produced in the concave depression, it is produced under the same conditions as described above.

After that, by removing the fourth mask 11, the positive electrode film 3 was laminated in the concave depression of the positive electrode collector electrode 2 formed on the substrate 1 as shown in FIG. A structure is obtained, and LiPON (Li ₃ PO _4−x N _x ), which is a lithium phosphate containing nitrogen, is laminated as the solid electrolyte membrane 4 on the obtained structure.

That is, a mask (thickness: 50 μm) having a square (8 mm × 10 mm) opening in the center is set in contact with the positive electrode film 3, and nitrogen is formed by RF magnetron sputtering using Li ₃ PO ₄ as a target. The solid electrolyte membrane 4 is produced by forming the film so that the film thickness becomes 1.0 μm. Here, the solid electrolyte membrane 4 made of LiPON includes a positive electrode membrane 3 made of LiCoO ₂ produced in a concave depression of the positive electrode collector electrode 2, and a peripheral portion of the concave depression of the positive electrode collector electrode 2 made of Pt. The film is formed so as to be continuously coated.

  Then, a lithium metal film is laminated as the negative electrode film 5. That is, the mask used when producing the solid electrolyte membrane 4 is removed, a mask (thickness: 50 μm) having a square (7 mm × 7 mm) opening in the center is set, and vacuum deposition using lithium as a deposition source A negative electrode film 5 is produced by forming a lithium metal film having a thickness of 0.5 μm by the method.

  Subsequently, a copper metal film is laminated as the negative electrode collector electrode 6. That is, a copper metal film having a film thickness of 0.5 μm is formed by a vacuum vapor deposition method in which the vapor deposition source is Cu, and the negative electrode collector electrode 6 that also functions as a negative electrode terminal is produced.

  Finally, an insulating parylene resin is laminated as the protective layer 7. In other words, a mask (thickness: 50 μm) having a square (13 mm × 13 mm) opening in the center is set, and a parylene resin is deposited to a thickness of 2.0 μm by thermal evaporation to protect it. Layer 7 is produced. Here, the protective layer 7 made of an insulating material is formed so as to cover the surface of the positive electrode collector electrode 2, the positive electrode film 3, the solid electrolyte membrane 4, the negative electrode film 5, and the negative electrode collector electrode 6 exposed to the outside air. To do.

  The all-solid-state lithium secondary battery in Example 1 manufactured in this way can avoid a short-circuit at the battery edge and is manufactured by a manufacturing method with a low incidence of defective products as described above. it can.

  In this embodiment, the case where Pt is used as the positive electrode collector electrode 2 and Cu is used as the negative electrode collector electrode 6 has been described. However, the present invention is not limited to this and does not react with lithium or has low reactivity. Any conductive material can be used as the positive electrode collector 2 or the negative electrode collector 6.

  In this embodiment, the case where a single layer of Pt is formed as the lower structure of the positive electrode collector electrode 2 has been described. However, the present invention is not limited to this, and the adhesion to the substrate 1 is improved. In addition, as the lower structure of the positive electrode collector electrode 2, a plurality of layers of films may be formed.

In this embodiment, LiPON is used as the solid electrolyte membrane 4. However, the present invention is not limited to this. For example, lithium ion conductive lithium-containing glass or lithium such as LiTi ₂ (PO ₄ ) ₃ is used. Any substance having lithium ion conductivity, such as a contained phosphate, can be used as the solid electrolyte membrane 4.

In the present embodiment, the case where metallic lithium is used as the negative electrode film 5 has been described. However, the present invention is not limited to this, and carbon, silicon, tin, an alloy containing these, or Li ₄ Ti Any material that can occlude and release lithium ions at a base potential, such as a metal oxide such as ₅ O ₁₂ , can be used as the negative electrode film 5.

  In this embodiment, the case where a parylene resin is used as the protective layer 7 has been described. However, the present invention is not limited to this, and a polymer resin such as parylene or an insulating property such as silicon nitride. Any material or moisture-resistant material such as a mixture of a polymer resin and an insulating material can be used as the protective layer 7.

  Moreover, although the present Example demonstrated the case where the positive electrode collector electrode 2 which has a concave hollow was produced on the board | substrate 1, this invention is not limited to this, The negative electrode collector electrode 6 which has a concave hollow Is produced on the substrate 1, and further, the negative electrode film 5 is produced in the concave depression, and the solid electrolyte film 4, the positive electrode film 3, the positive electrode collector electrode 2, and the protective layer 7 are laminated on this structure. It may be.

  In addition, the battery manufacturing method according to this embodiment can be applied regardless of the electrode, solid electrolyte, collector electrode, or protective layer deposition method. However, as a method for producing the positive electrode film, it is more preferable to use a sputtering method in which composition deviation hardly occurs and a highly crystalline film can be produced without heat treatment at high temperature by appropriately setting the film formation conditions. It is not limited to.

[Characteristics of all solid-state lithium secondary battery in Example 1]
Next, the characteristics of the all solid-state lithium secondary battery (see FIG. 1) manufactured in this way will be described with reference to FIGS. FIG. 3 is a diagram showing the charge / discharge characteristics of the all-solid-state lithium secondary battery in Example 1, and FIG. 4 is a diagram showing the cycle dependency of the discharge capacity of the all-solid-type lithium secondary battery in Example 1. It is.

The charge / discharge measurement of the all solid-state lithium secondary battery in Example 1 was performed in a voltage range of 2.5 to 4.3 V with a charge / discharge current density of 10 μA / cm ² . Here, the measurement was performed in a normal living environment where humidity was not controlled at room temperature. FIG. 3 shows a charge / discharge curve at the 20th cycle. Here, the charge / discharge capacity is the value of the positive electrode indicated by a value obtained by multiplying the effective area (cm ² ) of the battery by the film thickness (μm) of the positive electrode for easy comparison with Example 2 described later. The value per unit volume (μAh / cm ² μm) is shown.

  As shown in FIG. 3, the all-solid-state lithium secondary battery in Example 1 has a high average discharge voltage of about 3.9 V, almost the same charge capacity and discharge capacity, and is excellent in reversibility. I understand that.

As shown in FIG. 4, the all solid-state lithium secondary battery in Example 1 shows a large value of about 50 μAh / cm ² μm, although the discharge capacity slightly decreases with the cycle. Shows stable cycle dependency.

  Furthermore, in order to study the manufacturing conditions of the all-solid-state lithium secondary battery in Example 1, the surface where the peripheral edge of the concave depression of the positive electrode collector electrode 2 is in contact with the solid electrolyte membrane 4 and the positive electrode membrane 3 An all solid-state lithium secondary battery having a step with the surface in contact with the solid electrolyte membrane 4 in the range of 0.10 μm to 0.35 μm was manufactured by adjusting the sputtering time.

  As a result of investigating the performance of the manufactured all-solid-state lithium secondary battery, it was confirmed that when the step difference exceeds 0.2 μm, short-circuiting of the battery frequently occurs and the incidence of defective batteries is remarkably increased. That is, in order to manufacture a battery that operates satisfactorily, the above step is 20% or less of the thickness of the solid electrolyte membrane 4 (1 μm in this embodiment) (0.2 μm or less in this embodiment). It turned out to be desirable.

That is, from the above measurement results, the surface where the peripheral edge of the concave depression of the positive electrode collector electrode 2 produced on the substrate 1 is in contact with the solid electrolyte membrane 4 (LiPON) and the positive electrode membrane 3 (LiCoO ₂ ) The all-solid-state lithium secondary battery in which the level difference from the surface in contact with the solid electrolyte membrane 4 is 20% or less of the thickness of the solid electrolyte membrane 4 is an excellent battery in terms of charge / discharge characteristics and cycle dependency of discharge capacity. It became clear to show performance.

[Effect of Example 1]
As described above, according to Example 1, the positive electrode collector electrode 2 manufactured on the substrate 1 has at least one concave depression on the other surface facing the surface in contact with the substrate 1. In the concave depression of the positive electrode collector electrode 2 formed into a film, when the positive electrode film 3 is laminated, the peripheral edge of the concave depression of the positive electrode collector electrode 2 is in contact with the solid electrolyte membrane 4 Since the positive electrode film 3 is formed so that the step difference between the positive electrode film 3 and the surface where the positive electrode film 3 is in contact with the solid electrolyte film 4 is 20% or less of the film thickness of the solid electrolyte film 4, the short circuit at the battery edge portion is prevented. This can be avoided, and the incidence of defective products can be reduced. In addition, this makes it possible to reduce the effective area of the battery by forming an electrode film formed on the solid electrolyte so as to have a smaller area than the solid electrolyte in order to avoid short circuit at the battery edge. As a result, the inefficiency of batteries can be reduced, resulting in the solution to the inefficiency of the battery. " Become.

  Moreover, according to Example 1, since the solid electrolyte membrane 4 is formed so that the peripheral part of the concave hollow which the positive electrode collector electrode 2 has, and the surface of the positive electrode film | membrane 3 may be continuously coat | covered, board | substrate The positive electrode collector electrode 2 and the positive electrode film 3 manufactured on the substrate 1 can be densely coated with the solid electrolyte film 4 to further avoid a short circuit at the battery edge, and to further reduce the incidence of defective products. Is possible. That is, it is possible to prevent defects such as local non-uniformity in the thickness of the solid electrolyte film 4 due to the step between the positive electrode collector electrode 2 and the positive electrode film 3 and further avoid a short circuit at the battery edge portion, It becomes possible to lower the incidence of defective products.

  Further, according to Example 1, when viewed from the center of the opening of the concave depression of the positive electrode collector electrode 2, the bottom and side surfaces of the concave depression are formed by the peripheral portion of the opening of the concave depression. Since the positive electrode collector electrode 2 is formed so as not to be shielded, the positive electrode film 3 can be densely and uniformly laminated in the concave depression of the positive electrode collector electrode 2 to further avoid a short circuit at the battery edge, It becomes possible to lower the incidence of defective products.

  Further, according to Example 1, in each of the positive electrode film 3, the negative electrode film 5, the solid electrolyte film 4, the positive electrode collector electrode 2, and the negative electrode collector electrode 6, the protective layer 7 made of an insulating material is exposed on the surface. Therefore, it is possible to manufacture a battery having excellent stability and handling properties, and to further reduce the occurrence rate of defective products. That is, when a battery component includes a substance that deteriorates due to moisture in the atmosphere, the protective layer 7 made of at least one of an insulating organic substance and an insulating inorganic substance covers the battery part that is exposed to the outside air. Therefore, it is possible to manufacture a battery having excellent stability and handling properties by imparting excellent durability and lowering the incidence of defective products.

  Further, in the side wall part excluding the bottom part of the concave depression, the surface from the deepest part of the side wall part or the opening part of the concave depression to the opening part of the concave depression, By forming the positive electrode collector electrode 2 so as to be composed of an insulating material, a short circuit between the positive electrode collector electrode 2 and the negative electrode film 5 can be avoided, and the generation rate of defective products can be further reduced. It becomes possible. This will be described below.

  That is, after making a terminal (positive electrode terminal in FIG. 1) for connection with another device, in the side wall part excluding the bottom part of the concave depression made in the positive electrode collecting electrode 2, the deepest part of the side wall part or By forming the surface from the recessed opening to a certain depth from the recessed opening with an insulating material, it is possible to prevent the positive electrode collecting electrode 2 and the negative electrode film 5 from coming into contact with each other and causing a short circuit. it can.

  For example, in the case where the positive electrode film 3 is formed in the concave depression of the positive electrode collector electrode 2, the lower structure of the positive electrode collector electrode 2 is set to Pt in the steps shown in FIGS. ) To (F), when the upper structure of the positive electrode collector electrode 2 is made of polyethylene, it is possible to prevent the positive electrode collector electrode 2 and the negative electrode film 5 from coming into contact with each other to cause a short circuit.

  Alternatively, a conductive film such as Pt is first formed on the substrate 1, and then an insulating film such as polyethylene is laminated on the conductive film by a vapor deposition method or the like, and insulation is performed on at least one portion of the insulating film. The positive electrode collector electrode 2 having a concave depression is produced by opening a hole penetrating to the conductive film by a technique such as laser or lithography so that the conductive film remains around the conductive film. By producing the positive electrode film 3 in the concave recess, it is possible to prevent the positive electrode collector electrode 2 and the negative electrode film 5 from coming into contact with each other to cause a short circuit.

  As described above, the method for producing the positive electrode collector electrode 2 having a concave depression may be any method that is excellent in flatness and workability of the film to be produced. Etching techniques or the like can be used.

In Example 1 described above, an all solid-state lithium secondary battery manufactured using lithium cobalt oxide (LiCoO ₂ ) as the positive electrode film 3 has been described. In Example 2, lithium ions can be inserted and removed. As the positive electrode film 3 made of solid, “LiNi _0.5 Co _0.5 O ₂ ”, “LiMn ₂ O ₄ ”, “V ₂ O ₅ ”, which are transition metal oxides containing at least one of Co, Ni, Mn, and V, are used. The all-solid-state lithium secondary battery having the same structure as in Example 1 manufactured using each will be described.

[Method for producing all solid-state lithium secondary battery in Example 2]
The positive electrode film 3 made of each of “LiNi _0.5 Co _0.5 O ₂ ”, “LiMn ₂ O ₄ ”, and “V ₂ O ₅ ” was produced by a known method using an RF magnetron sputtering method. The film thicknesses were all 0.5 μm, and were produced in the same manner as in Example 1. Other battery components, the positive electrode collector electrode 2, the solid electrolyte membrane 4, the negative electrode membrane 5, the negative electrode collector electrode 6, and the protective layer 7, were also produced in the same manner as in Example 1.

[Characteristics of an all-solid-state lithium secondary battery in Example 2]
Next, the characteristics of the all solid-state lithium secondary battery in Example 2 manufactured as described above will be described with reference to FIG. FIG. 5 is a diagram showing the characteristics of the all-solid-state lithium secondary battery in Example 2.

As shown in FIG. 5, in order to investigate the characteristics of the all-solid-state lithium secondary battery in Example 2, the charge / discharge current density was set to 10 μA / cm ² for these three types of all-solid-state lithium secondary batteries manufactured. As a result, a charge / discharge test was conducted. In addition, since an operating voltage changes with kinds of positive electrode material to be used, the voltage range which performs a measurement according to the report for each battery was set (refer to "Measurement voltage range" in FIG. 5). The measurement was performed in a normal environment where the humidity was not controlled at room temperature.

FIG. 5 shows the results of the charge / discharge test of the all-solid-state lithium secondary battery in these three types of Example 2, and the results of the all-solid-state lithium secondary battery in Example 1 in which the positive electrode film 3 was produced using LiCoO ₂ . It shows with the result of a charge / discharge test.

The battery manufactured in Example 2 shows a high voltage (see “Average Discharge Voltage” in FIG. 5) as well as the battery manufactured in Example 1, and has a large discharge capacity of 40 to 70 μAh / cm ² μm. (See “Initial Discharge Capacity” in FIG. 5). In addition, even after 100 cycles of charging / discharging, about 90% of the discharge capacity was maintained compared to the initial discharge capacity, and charging / discharging could be performed stably (the “100th cycle” in FIG. 5). Discharge capacity ”).

That is, the all-solid-state lithium secondary battery in Example ₂ is not limited to LiCoO ₂ shown in Example 1, but includes at least one of Co, Ni, Mn, and V that can insert and desorb lithium ions. It shows that excellent battery performance can be realized by using the transition metal-based oxide containing as the positive electrode film 3.

[Effect of Example 2]
As described above, according to Example 2, since the transition metal oxide containing at least one of Co, Ni 2, Mn, and V is formed as the positive electrode film 3, the crystal structure and the transition metal ions in the crystal Judging from the valence state, the positive electrode film 3 can be manufactured using a material that can smoothly insert and desorb lithium ions, and an efficient all-solid-state lithium secondary battery with high energy density can be obtained. It can be easily manufactured.

[Comparative Example 1]
Next, the usefulness of the protective layer 7 mounted on the battery will be described with reference to FIG. FIG. 6 is a diagram for explaining the usefulness of the protective layer.

  First, in order to examine the usefulness of the protective layer 7 mounted on the battery, in the all solid-state lithium secondary battery in Example 1, the positive electrode collector electrode 2 and the positive electrode film 3 were formed without forming the protective layer 7. Then, an all solid lithium secondary battery including only the solid electrolyte membrane 4, the negative electrode membrane 5, and the negative electrode collector electrode 6 was produced as the all solid lithium secondary battery in Comparative Example 1.

  And the battery performance was evaluated about the all-solid-type lithium secondary battery in Example 1 (with the protective layer 7) and the all-solid-type lithium secondary battery in the comparative example 1 (without the protective layer 7), respectively. The evaluation of the battery performance was performed by measuring the change in the discharge capacity accompanying the cycle in the charge / discharge test, similarly to the above-mentioned [Characteristics of the all-solid-state lithium secondary battery in Example 1]. In addition, the charge / discharge test was performed in an actual living environment without controlling humidity at room temperature.

  As shown in FIG. 6, the all-solid-state lithium secondary battery (with the protective layer 7) in Example 1 shows a stable cycle (the change in the discharge capacity with the number of cycles is small), whereas the comparative example The all-solid-state lithium secondary battery (without protective layer 7) in No. 1 had the same initial discharge capacity, but in the subsequent cycles, the deterioration of the discharge capacity was remarkably abrupt.

  As a result, in order to prevent deterioration due to moisture, a protective layer made of either a polymer resin such as parylene or an insulating material such as silicon nitride, preferably a mixture of a polymer resin and an insulating material. 7, covering the surfaces exposed to the outside air in each of the positive electrode film 3, the negative electrode film 5, the solid electrolyte film 4, the positive electrode collector electrode 2, and the negative electrode collector electrode 6 is necessary to reduce the incidence of defective products. It is shown that.

[Comparative Example 2]
Finally, the effectiveness of the all-solid-state lithium secondary battery manufactured by the method for manufacturing the all-solid-state lithium secondary battery according to the present invention is compared with the effectiveness of the all-solid-state lithium secondary battery that has been conventionally used. It verified by comparing with.

  First, as an object to be compared with the all solid lithium secondary battery in Example 1, an all solid lithium secondary battery having a general structure was manufactured as shown in FIG. FIG. 7 is a bird's-eye view and a cross-sectional view for explaining the configuration of an all solid-state lithium secondary battery manufactured by the prior art.

As shown in FIG. 7, the all-solid-state lithium secondary battery manufactured by the conventional technique forms a Pt film as a positive electrode collector (positive electrode terminal) 2 and a LiCoO ₂ film as a positive electrode film 3 on a substrate 1. Then, LiPON is formed as the solid electrolyte film 4, Li is formed as the negative electrode film 5, Cu is formed as the negative electrode collector (negative electrode terminal) 6, and finally a parylene resin is formed as the protective layer 7. Manufactured. The negative electrode collector electrode 6 (Cu), the positive electrode film 3 (LiCoO ₂ ), the solid electrolyte film 4 (LiPON), and the negative electrode film 5 (Li) were formed in the same manner as in Example 1, and the film thickness was the same. It was. The positive electrode collector electrode 2 (Pt) was formed by RF magnetron sputtering in the same manner as the lower structure of the positive electrode collector electrode in Example 1. In order to avoid short-circuiting at the battery edge, the film area was set to positive electrode film: 0.8 cm ² , solid electrolyte film: 1.1 cm ² , and negative electrode film: 0.8 cm ² . Also, the membrane surface area of the positive electrode current electrode film and negative collector electrode film, was 0.9 cm ² and 0.8 cm ^2, respectively.

Further, in order to examine the occurrence rate (defective rate) of defective products such as low voltage and inability to charge / discharge, the all solid-state lithium secondary battery in Example 1 (see FIG. 1, hereinafter “in Example 1”). cell "and referred) and all-solid-state lithium secondary battery produced by the prior art (see FIG. 7, hereinafter," the referred to as conventional batteries "), produced 30 pieces each, 2 at a current density of 10 .mu.A / cm ^2. A charge / discharge cycle test was conducted in a voltage range of 5 to 4.3V.

As a result, when the “conventional battery” operates normally as a secondary battery, the same electrode material and solid electrolyte material as the “battery in Example 1” are formed with the same film thickness. The discharge capacity per unit volume (μAh / cm ² μm) shows the same value as “Battery in Example 1”, and the cycle characteristics when charging and discharging are repeated are the same as “Battery in Example 1” Had a tendency to However, when a large number of batteries were manufactured, there was a large difference in the incidence of defective products.

  FIG. 8 shows a table in which the number of defective products in “30 batteries in Example 1” and “30 conventional batteries” is summarized for each failure factor of the battery. In addition, FIG. 8 is a figure for demonstrating the comparison with the all-solid-state lithium secondary battery in Example 1, and the all-solid-state lithium secondary battery manufactured by the prior art.

  Here, the cause of failure is “(1) Low voltage: extremely low initial voltage (open circuit voltage) of 2V or less (usually 3V or more)”, “(2) Impossible charge / discharge: completely due to short circuit. It was classified by three factors, “Those that cannot be charged / discharged” and “(3) Poor cycle characteristics: those with significant cycle deterioration compared to FIG. 4”. As shown in FIG. 8, in the “battery in Example 1”, the rate of occurrence of defective products is as low as about 3%, whereas in the “conventional battery”, the rate of occurrence of defective products is extremely high at about 40%. I understand that it is expensive.

A similar study was conducted on an all-solid-state lithium secondary battery using LiNi _0.5 Co _0.5 O ₂ , LiMn ₂ O ₄ , and V ₂ O ₅ as the positive electrode film 3 in Example 2, according to the present invention. A result similar to this comparative example was obtained that the battery having the structure has a significantly lower occurrence rate of defective products than the “conventional battery”.

  From the above results, it was demonstrated that the method for producing an all-solid-state lithium secondary battery according to the present invention is an easy and efficient method with a low incidence of defective products. From the above results, according to the present invention, it is clear that the manufactured battery has a very high performance, and in the future, on an electronic circuit board, a silicon wafer, an IC card, and an RF-ID tag. This shows that an embedded battery can be manufactured directly in the same manner as in the above embodiment. In addition, since the all-solid-state lithium secondary battery can function normally as a battery even if it is bent or bent, it is suitable for a sealed battery that is attached to a curved surface or a paper display that is used like paper. It is also promising as a driving source.

  As described above, the method for producing an all-solid-state lithium secondary battery according to the present invention includes an all-solid-state lithium secondary battery having a configuration in which a solid electrolyte membrane is sandwiched and stacked between a positive electrode film and a negative electrode film. The present invention provides an all solid-state lithium secondary battery that is useful for manufacturing and is particularly suitable for manufacturing an all-solid-state lithium secondary battery with a low occurrence rate of defective products and a low occurrence rate of defective products.

2 is an overhead view and a cross-sectional view for explaining a configuration of an all solid-state lithium secondary battery in Example 1. FIG. 3 is a cross-sectional view for explaining a process from film formation of a positive electrode collector electrode to film formation of a positive electrode film of an all solid-state lithium secondary battery in Example 1. FIG. It is a figure which shows the charging / discharging characteristic of the all-solid-state lithium secondary battery in Example 1. FIG. It is a figure which shows the cycle dependence of the discharge capacity of the all-solid-type lithium secondary battery in Example 1. FIG. FIG. 4 is a diagram showing characteristics of an all solid-state lithium secondary battery in Example 2. It is a figure for demonstrating the usefulness of a protective layer. It is the bird's-eye view and sectional drawing for demonstrating the structure of the all-solid-state lithium secondary battery manufactured by the prior art. It is a figure for demonstrating the comparison with the all-solid-state lithium secondary battery in Example 1, and the all-solid-state lithium secondary battery manufactured by the prior art. It is a figure for demonstrating the problem of a prior art.

Explanation of symbols

1 Substrate 2 Positive electrode collector (positive electrode terminal)
3 Positive Electrode Membrane 4 Solid Electrolyte Membrane 5 Negative Electrode Membrane 6 Negative Electrode Current Collector (Negative Electrode Terminal)
7 Protective layer 8 First mask 9 Second mask 10 Third mask 11 Fourth mask

Claims (6)

A solid electrolyte membrane made of a lithium ion conductive solid is sandwiched between a positive electrode membrane made of a solid capable of inserting and removing lithium ions and a negative electrode membrane made of a solid capable of inserting and extracting lithium metal or lithium ions. An all-solid-state lithium secondary battery manufacturing method for manufacturing an all-solid-type lithium secondary battery having a configuration of being stacked,
Of the collector electrodes that are in contact with each of the positive electrode film and the negative electrode film, the collector electrode that also contacts the substrate on which the all-solid-state lithium secondary battery is manufactured is the other surface that faces the surface that contacts the substrate. In the collector electrode film forming step of forming a film so as to have at least one concave depression,
When the electrode film as the positive electrode film or the negative electrode film is laminated in the concave recess of the collector electrode formed by the collector electrode forming step, the peripheral edge of the concave recess of the collector electrode the height of the surface part is in contact with the solid electrolyte membrane, height and are different resulting level difference surface on which the electrode film is in contact with the solid electrolyte membrane, becomes 20% or less of the thickness of the solid electrolyte membrane, And an electrode film forming step of forming the electrode film so that the entire periphery is surrounded by the collector electrode;
The peripheral edge of the concave depression of the collector electrode formed by the collector electrode film forming step and the surface of the electrode film formed by the electrode film film forming step are continuously coated. A solid electrolyte membrane forming step for forming the solid electrolyte membrane,
All-solid-state lithium secondary battery manufacturing method characterized by including.   In the collector electrode film forming step, when viewed from the center of the opening of the concave depression of the collector electrode, the bottom and side surfaces of the concave depression are not shielded by the peripheral portion of the opening of the concave depression. The method for producing an all solid state lithium secondary battery according to claim 1, wherein the collector electrode is formed as described above. The all solid according to claim 1, further comprising a positive electrode film forming step of forming a transition metal-based oxide containing at least one of Co, Ni 2, Mn, and V as the positive electrode film. Type lithium secondary battery manufacturing method.   In the collector electrode film forming step, in the side wall portion excluding the bottom surface portion of the concave depression, from the deepest portion of the side wall portion or the opening portion of the concave depression, the concave depression The method for producing an all-solid-state lithium secondary battery according to any one of claims 1 to 3, wherein the collector electrode is formed so that a surface up to the opening is formed of an insulating material.   The positive electrode film, the negative electrode film, the solid electrolyte film, the collector electrode in contact with the positive electrode film, and the collector electrode in contact with the negative electrode film are coated with a protective layer made of an insulating material on the surface exposed to the outside air. The method for producing an all solid lithium secondary battery according to claim 1, further comprising a protective layer coating step.   An all solid lithium secondary battery manufactured by the method for producing an all solid lithium secondary battery according to claim 1.

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