JP5415099B2 - Method for manufacturing thin-film solid secondary battery - Google Patents

Description

The present invention relates to a method of manufacturing a thin-film solid secondary battery, in particular, aims to simplify the manufacturing process using a mask, a method for producing a good have thin film solid state secondary battery of the yield.

  Currently, small portable devices such as mobile phones are widely spread, and are becoming smaller, lighter, and more multifunctional. Accordingly, batteries required for driving these devices are also required to be smaller and have higher energy density. Lithium ion secondary batteries have a higher energy density than other batteries and can be used in a wide range of applications, and are currently most widely used.

  Recently, safety and high-temperature resistance have become important elements of lithium ion secondary batteries. However, conventional batteries that use electrolytes have risks such as liquid leakage and explosion due to thermal expansion. There are aspects that are not perfect for high temperature and high temperature resistance. For example, the upper limit of the temperature at which the battery can operate is about 80 ° C. for a normal lithium ion secondary battery using a solution electrolyte, and if the temperature rises higher than that, the battery characteristics deteriorate, and an unexpected situation due to thermal expansion May occur.

  Further, with regard to miniaturization and thinning, conventional batteries using an electrolytic solution have limitations due to the thickness of the container. For this reason, an all-solid battery using a gel electrolyte or a solid electrolyte instead of a solution has been proposed. For example, a polymer battery using a gel electrolyte (see, for example, Patent Document 1) or a solid electrolyte is used. Thin film solid secondary batteries (see, for example, Patent Documents 2 and 3) have been proposed.

  The polymer battery described in Patent Document 1 has a positive electrode current collector inside an exterior body, a composite positive electrode containing a polymer solid electrolyte inside, an electrolyte layer made of an ion conductive polymer compound, and a polymer solid electrolyte inside. A composite negative electrode and a negative electrode current collector are sequentially arranged.

  Such a polymer battery can be made thinner and smaller than a normal lithium ion secondary battery using an electrolytic solution, and the temperature at which stable battery operation can be improved to about 100 ° C. However, since a gel electrolyte, a bonding agent, a sealing member, and the like are required, the thickness is about 0.1 mm, which is not suitable for further thinning and miniaturization. In addition, since the electrolyte is a polymer, the structure changes when the temperature reaches about 150 ° C., and the battery itself collapses. Therefore, there is a problem in use at a higher temperature.

  On the other hand, as described in Patent Documents 2 and 3, the configuration of the thin film solid secondary battery is as follows: a current collector thin film, a negative electrode active material thin film, a solid electrolyte thin film, a positive electrode active material thin film, and a current collector thin film on a substrate. A stacked structure or a structure in which the above layers are stacked in the reverse order on the substrate. With such a configuration, the thin-film solid secondary battery can be made as thin as about 1 μm except for the substrate. Further, if the thickness of the substrate is reduced or a thin solid electrolyte film is used instead of the substrate, the overall thickness can be reduced and the size can be reduced. Furthermore, since it is an all-solid-state thin film solid secondary battery, it can be provided with high safety without inconvenience such as liquid leakage.

  Regarding the manufacturing technology of a thin film solid secondary battery, when laminating each layer of a thin film solid secondary battery (for example, a thin film solid lithium secondary battery), the material and the film forming technique are applied by a dry process such as a sputtering technique and a vacuum deposition technique. Various materials and techniques have been proposed. Among them, the film formation technology by sputtering is not only capable of forming a film with various targets in accordance with recent technological advances, but also downsizing the apparatus, simplifying the film formation process, and the costs associated therewith. This is a technology that is very important in the manufacturing technology of thin film solid state secondary batteries because it can be down.

  In the sputtering technique, as a method for controlling the film formation area, a method is often used in which a mask is attached to a substrate, the substrate film formation surface side is partially covered, and a film is formed only on an opening portion of the mask. Basically, in the film formation of the five layers constituting the thin film solid state secondary battery, it is necessary to exchange the mask for each lamination process in order to form each film in an arbitrary two-dimensional shape. However, when this mask is replaced, a slight “deviation” occurs due to technical problems. Along with this “deviation”, the positive electrode film (positive electrode current collector layer and positive electrode active material layer) and negative electrode film (negative electrode current collector). The body layer and the negative electrode active material layer) are in contact with each other at the end of the film, causing a short circuit. Therefore, despite the fact that a high-performance all-solid-state lithium secondary battery can be manufactured by the sputtering technique, there is a possibility that a defective product may be generated due to the above problems.

  On the other hand, in Patent Document 4, a recess is formed in a substrate, and four layers of an active material layer of a lower electrode, a solid electrolyte layer, an active material layer of an upper electrode, and an upper electrode current collector layer are sequentially formed in the recess. By doing so, it is said that there is no need to replace the mask. That is, when the four layers are formed, the layers are sequentially stacked in the concave portion, so that it is not necessary to replace the mask for controlling the area of each film, and therefore it is possible to avoid the occurrence of mask displacement. At the same time, since the end portions of the respective films are uniformly formed, it is proposed that a short circuit caused by contact between the positive electrode film and the negative electrode film can be prevented and the incidence of defective products is low. Furthermore, it is said that the deterioration of the battery function due to the mixing of foreign matters accompanying the mask exchange at the time of forming each layer can be solved.

Japanese Patent Laid-Open No. 10-74496 Japanese Patent Laid-Open No. 10-284130 JP 2002-42863 A JP 2008-140705 A

  In the technique of Patent Document 4, a mask is exchanged by forming a recess in a substrate and forming an active material layer of a lower electrode, a solid electrolyte layer, an active material layer of an upper electrode, and an upper electrode current collector layer in the recess. It is said that the time “shift” is eliminated, thereby reducing the incidence of short circuits, but in a thin-film solid secondary battery, it cannot function with only the four layers. In order for the thin film solid secondary battery to function, the lower electrode current collector layer is indispensable, and an electrode lead-out terminal portion must be formed in the lower electrode current collector layer. Since the lower electrode current collector layer has a different external shape from the other layers, the mask is changed after the lower electrode current collector layer is formed, and then the lower electrode active material layer, the solid electrolyte layer, and the upper electrode A method of laminating an active material layer and an upper electrode current collector layer in order is common.

  Therefore, in the technique of Patent Document 4, it is necessary to open the atmosphere once after the lower electrode current collector is formed. This is because when the current collector layer of the lower electrode is formed on the bottom surface of the opening, an electrode terminal is formed on the substrate surface at the same time, and then a step of connecting the electrode terminal and the lower electrode current collector layer is necessary. Because it becomes. Therefore, the surface of the lower electrode current collector layer that becomes the interface with the active material layer of the lower electrode to be laminated is oxidized due to exposure to the atmosphere due to mask exchange, alteration due to moisture, and the battery accordingly The problem that the performance (for example, battery life) is reduced is not solved, and in addition, the manufacturing process of the thin film solid secondary battery is complicated.

An object of the present invention is to provide a thin film solid secondary battery including a lower electrode current collector layer, a lower electrode active material layer, a solid electrolyte layer, an upper electrode active material layer, and an upper electrode current collector layer. in film formation by five layers sputtering comprising prevents contamination of foreign substances due to mask exchange, a method of manufacturing a thin-film solid secondary battery which aimed to reduce the short-circuit occurring between the upper and lower electrodes by the position of the mask and the substrate is deviated It is to provide.
Another object of the present invention is to provide a method of manufacturing a thin-film solid secondary battery long that can maintain the voltage.

  According to the method for manufacturing a thin-film solid secondary battery according to the present invention, the object is to provide a lower electrode current collector layer, a lower electrode active material layer, a solid electrolyte on the conductive layer of a substrate having a conductive layer on the surface. A method of manufacturing a thin-film solid secondary battery in which a layer, an active material layer of an upper electrode, and an upper electrode current collector layer are respectively laminated in a predetermined thickness in this order, the lower electrode current collector layer, A film forming step of continuously forming the active material layer of the lower electrode, the solid electrolyte layer, the active material layer of the upper electrode, and the upper electrode current collector layer to a predetermined thickness using the same mask; That is solved.

As described above, the five layers constituting the thin-film solid-state secondary battery including the lower electrode current collector layer can be continuously formed in the same film forming apparatus by the same mask without opening to the atmosphere. Impurities that deteriorate the battery performance at the interface between the five layers by preventing the introduction of impurities and the generation of impurities by continuously forming five layers from the lower electrode current collector layer to the upper electrode current collector layer. It is possible to reduce the possibility of occurrence.
Furthermore, when the five layers from the lower electrode current collector layer to the upper electrode current collector layer are formed, the positions of the respective layers are not shifted, thereby preventing a short circuit caused by contact between the positive electrode film and the negative electrode film. Can be prevented.

At this time, the lower electrode current collector layer is a positive electrode current collector layer, the lower electrode active material layer is a positive electrode active material layer, the upper electrode active material layer is a negative electrode active material layer, and the upper electrode current collector layer Is a negative electrode current collector layer, and each layer is preferably formed and laminated in this order on the conductive layer.
According to this structure, when the steel work a thin film solid state lithium secondary battery, lithium contained in the positive electrode active material layer is moved in the negative electrode active material layer or the like during the film formation, it may cause irreversible capacity, reduced battery characteristics Can be prevented. That is, since the lithium ion movable part can be sealed, it is possible to protect the surface of the positive electrode active material layer containing lithium, to suppress the deterioration of the battery performance, and to maintain the battery performance for a long period of time. Become.

The solid electrolyte layer includes lithium phosphate (Li ₃ PO ₄ ), lithium phosphate oxynitride glass (LiPON) in which oxygen of the lithium phosphate is partially substituted with nitrogen, or a transition metal and Li and N. One of the complex oxides is preferable. Thus, the charging / discharging characteristic of a lithium ion secondary battery can be improved by containing these compounds with favorable lithium ion conductivity in the solid electrolyte layer.

  Furthermore, it is preferable that the conductive layer is an electrode extraction metal film and is formed in a step of forming a metal layer on an insulating substrate. Thereby, the influence which a board | substrate has on the performance of a thin film solid secondary battery can be reduced, and the charge / discharge characteristic of a thin film solid secondary battery can be improved.

  At this time, it is preferable that the electrode extraction metal film and the lower electrode current collector layer are made of the same material. Thereby, since the electrode extraction metal film and the lower electrode current collector can be formed with the same target, the number of targets required for film formation is reduced during the manufacture of the thin film solid secondary battery, the operation is simplified, It is possible to shorten the film formation time and simplify the manufacturing apparatus of the thin film solid secondary battery.

Furthermore, the negative electrode current collector layer of the electrode current collector layer is preferably niobium, and the negative electrode active material layer of the electrode active material layer is preferably niobium oxide (Nb ₂ O ₅ ). At this time, the negative electrode current collector layer and the negative electrode active material layer can be manufactured by using the same niobium metal target and adjusting the oxygen gas flow rate during sputtering film formation. Therefore, when manufacturing a thin film solid-state secondary battery, the number of targets used for film formation and the number of power source switching can be reduced, the manufacturing process can be simplified, the operation can be simplified, and the apparatus can be downsized. Can do. In addition, since the same material metal can be used, it is not necessary to replace the metal target, so that it is possible to improve the work efficiency of the operator and prevent the contamination of impurities, thereby ensuring the uniformity of the performance of the obtained battery. it can.

  According to the method for producing a thin film solid secondary battery of claim 1 of the present invention, the lower electrode current collector layer, the lower electrode active material layer, the solid electrolyte layer, the upper electrode active material layer, the upper electrode current collector layer These five layers can be formed by continuous film formation in the same film forming apparatus without opening to the atmosphere. By performing the five layer continuous film formation, contamination of foreign matters and generation of impurities are hindered. The possibility that impurities that deteriorate the battery performance are generated at the interface is reduced. Further, the number of times of switching the power source can be reduced, the manufacturing process can be simplified, the operation can be simplified, and the apparatus can be downsized.

According to the method for manufacturing a thin film solid secondary battery of the present invention, when the layers of the thin film solid lithium secondary battery are stacked, it is possible to continuously form films using the same mask. Since the operating part of the battery cell is consistently produced in a high-vacuum film forming apparatus, it can be said that the battery performance is not easily affected by environmental changes such as ambient temperature, humidity, and cleanliness. As a result, it is possible to prevent foreign matters from being mixed during film formation, and accordingly, occurrence of a short circuit can be prevented. Therefore, more stable and reproducible battery performance can be obtained, and the battery can be manufactured with high yield. In addition, the continuous film formation does not adversely affect the performance due to the discontinuity between the current collector interface and the active material layer interface, and an improvement in battery performance can be expected.

Furthermore, not only the battery performance is improved, but the production time of the battery cell is greatly shortened by continuous film formation, so that the manufacturing cost can be reduced. This is because the evacuation time of the vacuum film forming apparatus performed every time the vacuum film forming apparatus is opened to the atmosphere for mask exchange can be omitted.
Furthermore, even when multiple persons in charge are involved in the manufacturing process, there are few operations in the atmosphere where the thin film constituting the battery cell is likely to deteriorate, so depending on the difference in work efficiency between persons in charge, the battery It is unlikely that there will be a difference in performance.

Also, as claimed in claim 2, when manufactured create a thin film solid state lithium secondary battery, the lower electrode collector layer and the cathode current collector layer, a positive electrode active material layer of the active material layer of the electrode, the solid electrolyte layer, an upper When the active material layer of the electrode is the negative electrode active material layer, the upper electrode current collector layer is the negative electrode current collector layer, and each layer is laminated in this order on the lower electrode extraction metal film, lithium contained in the positive electrode active material layer is formed. It moves to the negative electrode active material layer and the like, causing irreversible capacity and preventing battery characteristics from deteriorating.

Moreover, according to invention of Claim 3, while providing the above-mentioned effect, the charging / discharging characteristic of a lithium ion secondary battery is improved by containing the said compound with favorable electroconductivity of lithium ion in a solid electrolyte layer. Can do.
According to the invention of claim 4, by selecting an insulator as the substrate, the type of the substrate on which the thin film solid secondary battery can be manufactured is not limited, and various materials including an insulator film can be used. .

  Further, as described in claim 5, by using the same material for the electrode lead-out metal film and the lower electrode current collector layer, the number of targets required for film formation can be reduced, and the operation can be simplified and the film formation time can be reduced. Shortening and simplification of a thin film solid state secondary battery manufacturing apparatus can be achieved.

Further, according to the invention of claim 6, in the electrode current collector layer, the negative electrode current collector layer is niobium, and the negative electrode active material layer is niobium oxide (Nb ₂ O ₅ ) in the electrode active material layer. Since the negative electrode current collector layer and the negative electrode active material layer can be formed with a single target during the continuous film formation process, the film formation process can be simplified .

It is a schematic side view of the thin film solid secondary battery which concerns on embodiment of this invention. It is a graph of the cycle characteristics of a thin film solid secondary battery. It is a graph of the discharge curve of a thin film solid secondary battery. 6 is a schematic side view of a thin-film solid secondary battery according to an embodiment of Comparative Example 1. FIG. 6 is a schematic side view of a thin-film solid secondary battery according to an embodiment of Comparative Example 2. FIG.

A method of manufacturing a thin film solid secondary battery according to an embodiment of the present invention will be described with reference to the drawings. The materials, arrangements, configurations, and the like described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
FIG. 1 is a schematic side view showing a thin film solid secondary battery according to an embodiment of the present invention. The thin film solid secondary battery according to the present embodiment has an electrode extraction metal film 2 and a lower electrode current collector on a substrate 1. The layer 3, the active material layer 4 of the lower electrode, the solid electrolyte layer 5, the active material layer 6 of the upper electrode, and the thin film of the upper electrode current collector layer 7 are sequentially laminated.

In the method for manufacturing a thin film solid secondary battery of the present invention, the lower electrode current collector layer 3, the lower electrode active material layer 4, the solid electrolyte layer 5, and the upper electrode active so as to overlap the electrode extraction metal film 2. The material layer 6 and the upper electrode current collector layer 7 are successively formed in this order using the same mask until each layer has a predetermined thickness.
In this manner, the lower electrode current collector layer 3 and subsequent layers are formed in a vacuum state without changing the mask and opening to the atmosphere.

In the present embodiment, either the lower electrode current collector layer 3 or the upper electrode current collector layer 7 is a negative electrode current collector layer, the negative electrode current collector is niobium, and the lower electrode active material layer 4 Alternatively, when any of the active material layers 6 of the upper electrode is a negative electrode active material layer and the negative electrode active material is niobium oxide (Nb ₂ O ₅ ), the film can be formed by a DC sputtering method. Compared to the method, the film formation speed is improved, the film formation time can be shortened, the production efficiency can be improved, and the manufacturing cost can be reduced.

  It is considered that various operating principles and types of thin film solid-state secondary batteries having the above-described configuration can be manufactured. Among them, a thin-film solid-state lithium secondary battery is preferable from the viewpoint of excellent battery characteristics such as energy density and relatively easy thinning of the constituent materials.

Here, when a thin film solid lithium secondary battery is manufactured, the lower electrode current collector layer 3 is a positive electrode current collector layer, the lower electrode active material layer 4 is a positive electrode active material layer, and the upper electrode active material layer 6 is formed. Film formation is performed using the negative electrode active material layer and the upper electrode current collector layer 7 as a negative electrode current collector layer. In this way, it is desirable to produce the layers in order from the positive electrode side.
The reason for stacking in order from the positive electrode side is to protect the surface of the positive electrode active material layer containing lithium. Conversely, when a battery cell is manufactured by stacking from the negative electrode side, the lithium contained in the positive electrode active material layer Is moved to the negative electrode active material layer or the like during film formation, causing irreversible capacity and possibly reducing battery characteristics.

  As a method for forming each thin film, a vacuum film forming method such as a sputtering method, an electron beam vapor deposition method, a heating steam method, a coating method, or the like can be used. It is preferable to use a vacuum film-forming method that can form a thin film more thinly and uniformly. More preferably, it is preferable to use a sputtering method in which there is little deviation in the atomic composition from the vapor deposition material and uniform film formation is possible.

  It is well known that a lithium-containing oxide, which is a constituent material of a lithium secondary battery, easily deteriorates due to moisture and oxidation. As a countermeasure, a dry room, a glove box, and the like are required. According to the present invention, the lower electrode current collector layer constituting the battery cell to the upper electrode current collector layer can be continuously produced in a vacuum film forming apparatus. Therefore, it is suitable as a method for manufacturing a lithium secondary battery.

  Hereinafter, the lower electrode current collector layer 3 is the positive electrode current collector layer 3, the lower electrode active material layer 4 is the positive electrode active material layer 4, the upper electrode active material layer 6 is the negative electrode active material layer 6, and the upper electrode current collector. The layer 7 is used as the negative electrode current collector layer 7, and an optimum form for manufacturing the thin film solid lithium secondary battery of this example will be described. The stacking order on the electrode extraction metal film 2 is the order in which the positive electrode current collector layer 3 and the negative electrode current collector layer 7, and the positive electrode active material layer 4 and the negative electrode active material layer 6 are replaced, that is, the negative electrode current collector layer. The order of the electric conductor layer 7, the negative electrode active material layer 6, the solid electrolyte layer 5, the positive electrode active material layer 4, and the positive electrode current collector layer 3 may be used.

As the substrate 1, glass, semiconductor silicon, ceramic, stainless steel, a resin substrate, or the like can be used. As the resin substrate, polyimide, PET, or the like can be used. A thin film that can be bent can be used for the substrate 1 as long as it can be handled without losing its shape. It is more preferable that these substrates have additional characteristics such as increasing transparency, preventing diffusion of alkali elements such as Na, increasing heat resistance, and providing gas barrier properties. A substrate on which a thin film such as SiO ₂ or TiO ₂ is formed by sputtering or the like may be used.

The electrode extraction metal film 2 may be a metal film having good adhesion to the substrate 1 and low electrical resistance. In order for the electrode extraction metal layer 2 to function well as an extraction electrode, the sheet resistance is desirably 1 kΩ / □ or less. When the film thickness of the electrode extraction metal layer 2 is set to 0.1 μm or more, the electrode extraction metal layer 2 needs to be formed of a substance having a resistivity of 1 × 10 ⁻² Ω · cm or less. As such a substance, for example, vanadium, titanium, niobium, aluminum, copper, nickel, gold or the like can be used. With these materials, the electrode lead-out metal layer 2 can be formed to a thickness of about 0.05 to 1 μm, which is as thin as possible and has a low electrical resistance.

  As the positive electrode current collector layer 3, a conductive film having good adhesion to the positive electrode active material layer 4 and low electric resistance can be used. Vanadium, titanium, niobium, aluminum, copper, nickel, gold or the like can be used in the same manner as the electrode extraction metal film 2. When the electrode extraction metal film 2 and the positive electrode current collector layer 3 are formed of the same material, the battery cell manufacturing process can be simplified, which is preferable.

The positive electrode active material layer 4 may be any material containing lithium and capable of detaching and occluding lithium ions, and is not particularly limited, but is preferably any one of transition metals such as manganese, cobalt, and nickel. A metal oxide thin film containing one or more and lithium is preferably used. For example, lithium-manganese oxide (LiMn ₂ O ₄ , Li ₂ Mn ₂ O ₄ etc.), lithium-cobalt oxide (LiCoO ₂ , LiCo ₂ O ₄ etc.), lithium-nickel oxide (LiNiO ₂ , LiNi ₂ O) ₄ ), lithium-manganese-cobalt oxide (LiMnCoO ₄ , Li ₂ MnCoO ₄ etc.), lithium-titanium oxide (Li ₄ Ti ₅ O ₁₂ , LiTi ₂ O ₄ etc.), etc. can be used. The film thickness of the positive electrode active material layer 4 is desirably as thin as possible, but is preferably about 0.05 to 5 μm that can secure a charge / discharge capacity.

The solid electrolyte layer 5 is composed of lithium phosphate (Li ₃ PO ₄ ) having good lithium ion conductivity, lithium phosphate oxynitride glass (LiPON) in which oxygen of the lithium phosphate is partially substituted with nitrogen, or Ta and Nb. Any one or more transition metals and composite oxides containing Li and N can be used. The thickness of the solid electrolyte layer 5 is preferably about 0.05 to 1 [mu] m, where generation of pinholes is reduced and as thin as possible.

The negative electrode active material layer 6 is not particularly limited as long as it can release and occlude lithium ions, and is preferably a silicon-manganese alloy (Si-Mn), a silicon-cobalt alloy (Si-Co). ), Silicon-nickel alloy (Si—Ni), lithium-titanium oxide (LiTi ₂ O ₄ , Li ₄ Ti ₅ O _12, etc.), niobium pentoxide (Nb ₂ O ₅ ), titanium oxide (TiO ₂ ), oxidation Indium (In ₂ O ₃ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), nickel oxide (NiO), indium oxide added with tin (ITO), zinc oxide added with aluminum (AZO), gallium Added zinc oxide (GZO), antimony added tin oxide (ATO), fluorine added tin oxide (FTO), lithium added It is preferable to use nickel oxide (NiO—Li) or the like.

As the negative electrode current collector layer 7, a conductive film having good adhesion to the negative electrode active material layer 6 and low electric resistance can be used.
Vanadium, titanium, niobium, aluminum, copper, nickel, gold or the like can be used in the same manner as the electrode extraction metal film 2 and the positive electrode current collector layer 3.

Further, when niobium oxide (Nb ₂ O ₅ ) is used as the negative electrode active material layer 6, oxygen during sputtering film formation using the same niobium metal target by using the negative electrode current collector layer 7 as niobium. It can be made by adjusting the gas flow rate. Thereby, when manufacturing a battery cell, the number of required targets and the number of power supplies can be reduced, the apparatus can be miniaturized, and the cost can be reduced.

When the thin-film solid secondary battery is charged, lithium is released from the positive electrode active material layer 4 as ions, and is inserted in the negative electrode active material layer 6 through the solid electrolyte layer 5. At this time, electrons are emitted from the positive electrode active material layer 4 to the outside.
Further, at the time of discharging, lithium is separated from the negative electrode active material layer 6 as ions and is inserted into the positive electrode active material layer 4 through the solid electrolyte layer 5. At this time, electrons are emitted from the negative electrode active material layer 6 to the outside.

  Next, examples and comparative examples of the present invention will be described with reference to the drawings. FIG. 2 is a graph showing comparison of cycle characteristics of battery cells in which the negative electrode active material and the negative electrode current collector are changed, and shows the relationship between the number of charge / discharge cycles and the discharge capacity. FIG. 3 is a graph showing comparison of discharge curves of battery cells in which the negative electrode active material and the negative electrode current collector are changed, and shows the relationship between the battery capacity and the battery voltage. FIG. 4 is a schematic side view of the thin-film solid secondary battery according to the embodiment of Comparative Example 1, and shows that the positive electrode active material layer 4, the solid electrolyte layer 5, and the negative electrode active material layer 6 are continuously formed. . FIG. 5 is a schematic side view of a thin-film solid secondary battery according to an embodiment of Comparative Example 2, in which a positive electrode active material layer 4, a solid electrolyte layer 5, a negative electrode active material layer 6, and a negative electrode current collector layer 7 are continuously formed. It shows that it did.

An electrode extraction metal film 2, a positive electrode current collector layer 3, a positive electrode active material layer 4, a solid electrolyte layer 5, a negative electrode active material layer 6, and a negative electrode current collector layer 7 are formed on a substrate 1 so as to have the configuration shown in FIG. sequentially formed by sputtering to manufactured create a thin film solid secondary battery. At this time, as described above, after the electrode extraction metal film 2 is formed on the substrate in advance, the mask is exchanged and the atmosphere is released, and then the positive electrode current collector layer 3, the positive electrode active material layer 4, and the solid electrolyte layer 5. The negative electrode active material layer 6 and the negative electrode current collector layer 7 were continuously formed.
As the substrate 1, soda lime glass having a length of 50 mm, a width of 50 mm, and a thickness of 1 mm was used.
The electrode extraction metal film 2 was formed by DC magnetron sputtering using a titanium (Ti) target. At this time, the film was formed with a DC power of 1 KW and no heating. As a result, a 0.1 μm titanium thin film was formed as the electrode extraction metal film 2.
Next, after the electrode extraction metal film 2 was formed, the atmosphere was released and the mask was exchanged. All subsequent manufacturing steps were performed continuously in a film forming apparatus that maintained a high vacuum state.
The positive electrode current collector layer 3 was formed by a DC magnetron sputtering method using a titanium (Ti) target in the same manner as the electrode extraction metal film 2. The film was formed with a DC power of 1 KW and no heating. As a result, a 0.1 μm titanium thin film was formed as the positive electrode current collector layer 3.

The positive electrode active material layer 4 was formed by RF magnetron sputtering using a lithium manganate (LiMn ₂ O ₄ ) target and introducing oxygen. The film was formed with an RF power of 1 KW and no heating. Thereby, a 0.2 μm thick LiMn ₂ O ₄ thin film was formed.
The solid electrolyte layer 5 was formed by RF magnetron sputtering using a sintered phosphor target of lithium phosphate (Li ₃ PO ₄ ) and introducing nitrogen. The film was formed with an RF power of 1 KW and no heating. Thereby, a 0.1 μm lithium phosphate oxynitride glass (LiPON) thin film was formed.
The negative electrode active material layer 6 was formed by DC magnetron sputtering using a niobium (Nb) target and introducing oxygen. The film was formed with a DC power of 1 KW and no heating. Thereby, a 0.1 μm niobium oxide thin film was formed.
The negative electrode current collector 7 was formed by a DC magnetron sputtering method using a niobium (Nb) target in the same manner as the negative electrode active material layer 6. The film was formed with a DC power of 1 KW and no heating. As a result, a 0.1 μm-thick niobium thin film was formed.

The thin-film solid secondary battery obtained as described above was subjected to X-ray diffraction measurement, and as a result, it was confirmed that no diffraction peak appeared. Thereby, it was confirmed that all the constituent layers were amorphous. Further, the yield was 91.0% of the thin film solid secondary battery manufactured created by the method described above (measurement number 78, the movable number 71 pieces).

Next, in order to evaluate battery performance, the charge / discharge characteristics were measured using a charge / discharge meter.
The measurement conditions were such that the current during charging and discharging was 0.02 mA, and the final voltages for charging and discharging were 3.5 V and 0.3 V, respectively. As a result, it was confirmed that repeated charge / discharge operations were exhibited.

[Comparative Example 1]
In Comparative Example 1, as in the example were made created by sputtering a thin film solid state secondary battery having the structure shown in FIG. 4. However, after the positive electrode current collector layer 3 was formed, the atmosphere was released and the mask was exchanged. Thereafter, three layers of the positive electrode active material layer 4, the solid electrolyte layer 5, and the negative electrode active material layer 6 were continuously formed, and the atmosphere was released and the mask was exchanged. Thereafter, a negative electrode current collector layer 7 was formed to produce a thin film solid secondary battery.
The film forming conditions for each of the positive electrode current collector layer 3, the positive electrode active material layer 4, the solid electrolyte layer 5, the negative electrode active material layer 6, and the negative electrode current collector layer 7 are the same as those in the example.

Also, the yield of the thin film solid secondary battery manufactured created by the above method was 77.0% (determined number 126, 97 movable few).

[Comparative Example 2]
In Comparative Example 2, as in the example were made created by sputtering a thin film solid state secondary battery having the structure shown in FIG. 5. However, after the positive electrode current collector layer 3 was formed, the atmosphere was released and the mask was exchanged. Thereafter, four layers of a positive electrode active material layer 4, a solid electrolyte layer 5, a negative electrode active material layer 6, and a negative electrode current collector layer 7 were continuously formed to produce a thin film solid secondary battery.
The film forming conditions for each of the positive electrode current collector layer 3, the positive electrode active material layer 4, the solid electrolyte layer 5, the negative electrode active material layer 6, and the negative electrode current collector layer 7 are the same as those in the example.

  As shown in FIG. 2, it was shown that when the number of times of charge / discharge is the same, the higher the number of layers to be continuously stacked, the higher the discharge capacity can be maintained. For example, in the 20th cycle, a thin-film solid secondary battery produced by continuously forming five layers by the method of the example has three layers (the positive electrode active material layer 4, the solid electrolyte layer 5, the negative electrode active material) by the method of Comparative Example 1. Material layer 6) It was shown that a discharge capacity about 1.3 times higher than that of a thin-film solid secondary battery produced by continuous film formation can be maintained. In addition, the thin film solid secondary battery produced by continuously forming five layers by the method of the example was divided into four layers (positive electrode active material layer 4, solid electrolyte layer 5, negative electrode active material layer 6, It was shown that the negative electrode current collector layer 7) can maintain a discharge capacity about 1.2 times higher than that of a thin film solid secondary battery produced by continuous film formation.

As shown in FIG. 3, it was shown that a higher battery voltage can be maintained as the number of layers to be continuously stacked increases with an equal battery capacity.
For example, when comparing battery capacities that can maintain a battery voltage of 1.0 V or more, a thin-film solid secondary battery produced by continuously forming five layers by the method of the example has three layers (positive electrode active) by the method of Comparative Example 1. Material layer 4, solid electrolyte layer 5, negative electrode active material layer 6) It was shown that the battery capacity was about 1.3 times that of a thin film solid secondary battery produced by continuous film formation. In addition, the thin film solid secondary battery produced by continuously forming five layers by the method of the example was divided into four layers (positive electrode active material layer 4, solid electrolyte layer 5, negative electrode active material layer 6, Negative electrode current collector layer 7) It was shown that the battery capacity was about 1.2 times that of a thin-film solid secondary battery produced by continuous film formation.

As described above, as a result of comparison with the case where three or four layers are continuously formed, the discharge curve becomes gentle when the five layers are continuously formed, and an effect of maintaining a predetermined voltage for a longer time is seen. It was. This can be achieved by continuously forming each layer, it is suppressed layers of degradation due to air release, suggesting a more a thin film solid state secondary battery of high performance could be made created. The battery was made created by depositing five layers continuously has also been shown that the yield than good batteries manufactured created by depositing four layers continuously.

  The following embodiments are also included in the present invention. That is, an electrode extraction metal film 2, a lower electrode current collector layer 3, a lower electrode active material layer 4, a solid electrolyte layer 5, an upper electrode electrode active material layer 6, an upper electrode current collector layer 7 on a substrate 1. Are formed in this order in a predetermined thickness, and a metal thin film secondary electrode 2 is formed on the substrate 1 with a predetermined thickness using a mask. A first film forming step, a mask exchanging step for exchanging a mask used in the first film forming step after the first film forming step, and an electrode extraction metal film formed in the first film forming step 2, using the same mask exchanged in the mask exchange step, the lower electrode current collector layer 3, the lower electrode active material layer 4, the solid electrolyte layer 5, and the upper electrode The electrode active material layer 6 and the upper electrode current collector layer 7 are continuously formed to a predetermined thickness. A second film forming step of, may be a method of manufacturing a thin film solid secondary battery, characterized by comprising comprises a.

  The thin-film solid-state secondary battery manufactured according to the present invention can be used as a power source for a composite apparatus equipped with a device, thereby driving the device stably for a long time. Examples of such devices include mobile devices such as mobile phones, notebook computers, digital cameras, and portable games.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Electrode extraction metal film 3 Lower electrode current collector layer (positive electrode current collector layer)
4 Active material layer of lower electrode (positive electrode active material layer)
5 Solid electrolyte layer 6 Upper electrode active material layer (negative electrode active material layer)
7 Upper electrode current collector layer (negative electrode current collector layer)

Claims (6)

A lower electrode current collector layer, a lower electrode active material layer, a solid electrolyte layer, an upper electrode active material layer, and an upper electrode current collector layer are arranged in this order on the conductive layer of the substrate having a conductive layer on the surface. A method for producing a thin-film solid secondary battery having a predetermined film thickness,
The lower electrode current collector layer, the lower electrode active material layer, the solid electrolyte layer, the upper electrode active material layer, and the upper electrode current collector layer are successively formed to a predetermined thickness using the same mask. A film forming process,
A method for producing a thin-film solid secondary battery, comprising:   The lower electrode current collector layer is a positive electrode current collector layer, the lower electrode active material layer is a positive electrode active material layer, the upper electrode active material layer is a negative electrode active material layer, and the upper electrode current collector layer is a negative electrode current collector. 2. The method of manufacturing a thin film solid state secondary battery according to claim 1, wherein each of the layers is formed in this order and laminated on the conductive layer. The solid electrolyte layer is composed of lithium phosphate (Li ₃ PO ₄ ), lithium phosphate oxynitride glass (LiPON) in which oxygen of the lithium phosphate is partially substituted with nitrogen, or a composite oxide containing a transition metal and Li and N The method for manufacturing a thin film solid state secondary battery according to claim 1, wherein the method is one of the objects.   2. The method of manufacturing a thin film solid secondary battery according to claim 1, wherein the conductive layer is an electrode extraction metal film, and is formed in a step of forming a metal layer on an insulating substrate.   2. The method for manufacturing a thin film solid secondary battery according to claim 1, wherein the electrode extraction metal film and the lower electrode current collector layer are made of the same material. The negative electrode current collector layer of the electrode current collector layer is niobium, and the negative electrode active material layer of the electrode active material layer is niobium oxide (Nb ₂ O ₅ ). The manufacturing method of the thin film solid secondary battery of description .

Images