Electrochemical cell and oxygen supply device

Abstract

An electrochemical cell that is free from liquid leakage and capable of generating oxygen with high efficiency even without containing an oxygen generation catalyst is provided. The electrochemical cell comprises: a positive electrode layer that generates oxygen during charging and contains an oxygen-evolving electrode, the oxygen-evolving electrode containing a metal oxide and a metal ion-conductive solid electrolyte; a negative electrode layer capable of depositing a metal derived from the metal oxide, capable of alloying with the metal, and capable of storing the metal; and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer and composed of the metal ion-conductive solid electrolyte. The difference ΔE between oxidative decomposition potential E1 of the metal oxide and potential E2 at which a metal ion generated by oxidative decomposition of the metal oxide is deposited as the metal is less than 2.90 V.

Description

Electrochemical cells and oxygen supply devices

[0001] This disclosure relates to an electrochemical cell and an oxygen supply device.

[0002] Oxygen supply devices that supply oxygen to the outside are known. For example, Patent Document 1 (Japanese Patent Application Publication No. 2023-011956) discloses an oxygen generating device that includes a second battery having a positive electrode which is an air electrode, a negative electrode containing zinc, and an electrolyte containing an aqueous alkali metal hydroxide solution. In this second battery, it is described that oxygen is generated at the positive electrode which has a shape such as a porous body, and zinc is deposited at the negative electrode based on a reduction reaction of zinc ions. Patent Document 2 (U.S. Patent Application Publication No. 2023 / 0386523) discloses a metal-air battery that generates oxygen, and it is described that this air battery has a metal as a first electrode, a metal oxide as a second electrode, and a liquid or solid electrolyte.

[0003] Japanese Patent Publication No. 2023-011956, U.S. Patent Application Publication No. 2023 / 0386523

[0004] Yusuke Daiko et al., "Palm-Sized Ag+ Ion Emission Gun Operated at Room Temperature in Non-Vacuum Atmosphere", Adv. Eng. Mater. 2018, 20, 1800198 (Supporting Information for Non-Patent Literature 1) The Chemical Society of Japan (ed.), "Chemical Handbook, Basic Edition II, Revised 5th Edition, 5th Printing", Maruzen Publishing, 2018, pp. II-291 to II-300

[0005] However, in oxygen generators such as the one disclosed in Patent Document 1, an alkali metal hydroxide aqueous solution is used as the electrolyte, which can cause the electrolyte to leak from the battery and have adverse effects on peripheral equipment and the human body. Furthermore, conventional oxygen supply devices have insufficient oxygen generation capacity, and the development of electrochemical cells and oxygen supply devices (including oxygen generation electrodes) that can generate oxygen more efficiently is desired. In addition, while lithium oxide is described as an example of a metal oxide in Patent Document 2, oxygen generation catalysts are generally used for oxygen supply by oxidative decomposition of such metal oxides. However, RuO ２ Because expensive compounds such as those mentioned above are often used, the manufacturing cost of oxygen supply devices is high. Furthermore, in order to maximize the catalytic effect and minimize the amount of catalyst used, processes such as atomization of the catalyst or support of the catalyst on a metal oxide may be considered, but these processes also increase the manufacturing cost of oxygen supply devices. Therefore, from the perspective of reducing the manufacturing cost of oxygen supply devices, the development of an electrochemical cell and oxygen supply device that do not contain an oxygen-evolving catalyst and generate oxygen during charging (including an oxygen-evolving electrode) is desirable.

[0006] The present inventors have now developed an electrochemical cell that generates oxygen during charging, and the oxidative decomposition potential E of a metal oxide １ The potential E is at which metal ions produced by the oxidative decomposition of metal oxides precipitate as metal. ２ We have found that by using a metal oxide as the oxygen generation electrode such that the difference ΔE is less than 2.90V, it is possible to provide an electrochemical cell that can generate oxygen efficiently without leakage and without containing an oxygen generation catalyst, as well as an oxygen supply device equipped therewith.

[0007] Therefore, the object of the present invention is to provide an electrochemical cell that does not leak and can generate oxygen with high efficiency even without containing an oxygen generation catalyst, and an oxygen supply device equipped therewith.

[0008] The following embodiments are provided according to this disclosure: [Embodiment 1] An electrochemical cell that generates oxygen during charging, comprising: a positive electrode layer including an oxygen generating electrode, wherein the oxygen generating electrode comprises a metal oxide and a metal ion conductive solid electrolyte; a negative electrode layer on which a metal derived from the metal oxide can be deposited, alloyed with the metal, or adsorbed; and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, comprising a metal ion conductive solid electrolyte, wherein the oxidative decomposition potential E of the metal oxide １ The metal ions produced by the oxidative decomposition of the metal oxide precipitate as metal at a potential E ２An electrochemical cell in which the difference ΔE is less than 2.90V. [Aspect 2] The electrochemical cell according to aspect 1, wherein the positive electrode layer further comprises an electron conduction aid. [Aspect 3] The electrochemical cell according to aspect 1 or 2, wherein the oxygen generation electrode does not contain an oxygen generation catalyst. [Aspect 4] The electrochemical cell according to any one of aspects 1 to 3, wherein the metal oxide is copper oxide and the metal ion conductive solid electrolyte is a copper ion conductive solid electrolyte. [Aspect 5] The electrochemical cell according to any one of aspects 1 to 3, wherein the metal oxide is silver oxide and the metal ion conductive solid electrolyte is a silver ion conductive solid electrolyte. [Aspect 6] The electrochemical cell according to any one of aspects 2 to 5, wherein the electron conduction aid comprises conductive carbon. [Aspect 7] The electrochemical cell according to any one of aspects 1 to 6, wherein the negative electrode layer and the solid electrolyte layer are adjacent to each other in such a way that a space is formed between them that allows for the deposition of the metal. [Aspect 8] The electrochemical cell according to any one of aspects 1 to 7, wherein the difference ΔE is less than 2.0V. [Aspect 9] An electrochemical cell according to any one of aspects 1 to 8, wherein the difference ΔE is less than 1.0V. [Aspect 10] An oxygen supply device comprising: an electrochemical cell according to any one of aspects 1 to 9; an outer casing having an internal space in which the electrochemical cell is housed, wherein at least a part of the outer casing has a function or structure that allows oxygen to permeate. [Aspect 11] An oxygen supply device according to aspect 10, further comprising: a positive electrode current collector layer disposed between the outer casing and the positive electrode layer, and / or a negative electrode current collector layer disposed between the outer casing and the negative electrode layer. [Aspect 12] An air battery comprising: an electrochemical cell according to any one of aspects 1 to 9; an outer casing having an internal space in which the electrochemical cell is housed, wherein at least a part of the outer casing has a function or structure that allows oxygen to permeate. [Aspect 13] A magnetic recording and reproducing apparatus comprising: an oxygen supply device according to aspect 10 or 11; at least one magnetic recording medium; at least one spacer; a spindle motor for rotationally driving the magnetic recording medium; and at least one magnetic head for recording and / or reproducing information on the magnetic recording medium.

[0009] It is a schematic cross-sectional view conceptually showing the electrochemical cell of the present disclosure. It is a schematic cross-sectional view showing an example of the oxygen supply device of the present disclosure. It is a perspective view showing an example of a coin-type oxygen supply device. It is a graph of a voltage-time curve during energization of the oxygen supply device in Example 4 of the present disclosure. It is a schematic diagram showing an example of a magnetic recording / reproducing apparatus using the oxygen supply device of the present disclosure.

[0010] Electrochemical Cell The present disclosure relates to an electrochemical cell that generates oxygen during charging (typically for supplying oxygen). FIG. 1 conceptually shows an electrochemical cell 10 of the present disclosure, while FIG. 2 shows an example of an oxygen supply device 20 including the electrochemical cell 10. The electrochemical cell 10 includes a positive electrode layer 12 including an oxygen generation electrode, a negative electrode layer 14, and a solid electrolyte layer 16 interposed between the positive electrode layer 12 and the negative electrode layer 14. The oxygen generation electrode includes a metal oxide and a metal ion conductive solid electrolyte. The negative electrode layer 14 is a layer on which a metal derived from the metal oxide can be deposited, which can be alloyed with the metal, or which can occlude the metal. The solid electrolyte layer 16 is composed of a metal ion conductive solid electrolyte. Further, in the electrochemical cell 10, the oxidative decomposition potential E of the metal oxide １ and the potential E at which metal ions generated by oxidative decomposition of the metal oxide are deposited as metal ２ has a difference ΔE (hereinafter referred to as potential difference ΔE) of less than 2.90 V. As described above, in the electrochemical cell 10 that generates oxygen during charging, by employing a metal oxide for which the potential difference ΔE is less than 2.90 V in the oxygen generation electrode, there is provided the electrochemical cell 10 that has no liquid leakage and can generate oxygen with high efficiency even without containing an oxygen generation catalyst, and the oxygen supply device 20 including the same. Further, the reaction for generating oxygen in an electrochemical cell (e.g., 2Cu ２ O → 4Cu ＋ + 4e － + O ２ ) is itself the charging reaction of the positive electrode (air electrode) of an air battery. Therefore, by adopting the above configuration in the electrochemical cell 10, there is provided the electrochemical cell 10 that has no liquid leakage and can perform the charging reaction of an air battery with high efficiency even without containing an oxygen generation catalyst, and an air battery (e.g., a metal-air secondary battery) including the same.

[0011] In other words, as mentioned above, in oxygen generators such as the one disclosed in Patent Document 1, an aqueous alkali metal hydroxide solution is used as the electrolyte, which can cause the electrolyte to leak from the battery and have adverse effects on peripheral equipment and the human body. Furthermore, conventional oxygen supply devices have insufficient oxygen generation capacity, and there is a need for the development of electrochemical cells and oxygen supply devices (including oxygen generation electrodes) that can generate oxygen more efficiently. In addition, Patent Document 2 describes lithium oxide as an example of a metal oxide, but oxygen generation catalysts are generally used for oxygen supply by oxidative decomposition of such metal oxides. However, the catalyst is RuO ２ Because expensive compounds such as these are often used, the manufacturing cost of oxygen supply devices increases. Furthermore, in order to maximize the catalytic effect and minimize the amount of catalyst used, processes such as atomization of the catalyst or support of the catalyst on a metal oxide may be considered, but these processes also increase the manufacturing cost of the oxygen supply device. Therefore, from the viewpoint of reducing the manufacturing cost of oxygen supply devices, there is a need for the development of an electrochemical cell and oxygen supply device that do not contain an oxygen-evolving catalyst and generate oxygen during charging (including an oxygen-evolving electrode). These problems are successfully solved according to the present invention. Specifically, in the electrochemical cell 10, a solid electrolyte layer 16 composed of a metal ion-conducting solid electrolyte can be used instead of an electrolyte (i.e., an all-solid-state electrochemical cell configuration can be adopted), so that an electrochemical cell 10 and oxygen supply device 20 without liquid leakage can be realized. Furthermore, in the electrochemical cell 10 and oxygen supply device 20, by employing a metal oxide with a potential difference ΔE of less than 2.90 V as the oxygen generation electrode, a catalyst for the oxygen generation reaction can be eliminated. This makes it possible to provide an electrochemical cell 10 and an oxygen supply device 20 equipped therewith that can generate oxygen with high efficiency while keeping material and manufacturing costs low.

[0012] In the electrochemical cell 10 (and oxygen supply device 20), an oxidative decomposition reaction of metal oxides occurs in the positive electrode layer 12, specifically, as shown in the following formula: 2M ２／ｎ O → 4 / nM ｎ＋ + 4e－ + O ２ ↑ (1) The reaction shown in the formula (wherein M is the metal constituting the metal oxide and n is the valence of M) proceeds. For example, Cu as the metal oxide ２ When O is used, M = Cu and n = 1. That is, the metal oxide is reduced in the positive electrode layer 12. As a result, oxygen is generated in the positive electrode layer 12, and metal ions and electrons are released. The metal ions then reach the negative electrode layer 14 via the metal ion conductive solid electrolyte that constitutes the solid electrolyte layer 16, and the electrons reach the negative electrode layer 14 via the external power supply and wiring. That is, in the negative electrode layer 14, a reaction occurs in which metal ions generated by the oxidative decomposition of the metal oxide are deposited as metal, specifically, as shown in the following equation: M ｎ＋ + n・e － → The reaction represented by M (2) (wherein M is the metal constituting the metal oxide and n is the valence of M) proceeds, and metal ions and electrons combine to precipitate a metal derived from the metal oxide. Alternatively, in the negative electrode layer 14, alloying of the metal derived from the metal oxide and the metal constituting the negative electrode layer 14 may proceed, or intercalation of the metal derived from the metal oxide may proceed.

[0013] As described above, in the positive electrode layer 12, the oxidative decomposition reaction of the metal oxide proceeds according to the above formula (1), and the oxidative decomposition potential of the metal oxide in this reaction is E １ This is assumed. On the other hand, in the negative electrode layer 14, a reaction proceeds in which metal ions produced by the oxidative decomposition of metal oxides are deposited as metal according to the above formula (2), and the potential at which the metal ions are deposited as metal at this time is called the metal deposition potential E ２ Let's assume that the oxidation decomposition potential E １ and metal deposition potential E ２ The difference ΔE (= E １ -E ２As mentioned above, the potential difference ΔE is less than 2.90V. This makes it possible to realize an electrochemical cell 10 that can generate oxygen with high efficiency even without containing an oxygen generation catalyst. The potential difference ΔE with respect to the metal oxide is not particularly limited as long as it is less than 2.90V, but is preferably less than 2.50V, more preferably less than 2.00V, and even more preferably less than 1.00V. The lower limit of this potential difference is not particularly limited, but is typically 0.01V or more, more typically 0.02V or more, and even more typically 0.04V or more.

[0014] Oxidative decomposition potential E １ and metal deposition potential E ２ The difference ΔE is the standard potential E° of the redox reaction, which is calculated using the Nernst equation. That is, this standard potential E° is calculated using the following formula, where ΔG° is the standard Gibbs free energy of formation of the metal oxide, Faraday constant F, and n is the number of electrons in the reaction: E° = -ΔG° / nF. The standard Gibbs free energy of formation ΔG° for various metal oxides is publicly known and can be found, for example, by referring to Non-Patent Literature 3 (edited by the Chemical Society of Japan, "Chemical Handbook Basic Edition II Revised 5th Edition, 5th Printing", Maruzen Publishing, 2018, pp. II-291 to II-300). For reference, the potential difference ΔE obtained by the above calculation formula for various metal oxides is shown in Table 1 below.

[0015]

[0016] As described above, the electrochemical cell 10 comprises a positive electrode layer 12 containing an oxygen-generating electrode, a negative electrode layer 14, and a solid electrolyte layer 16 interposed between the positive electrode layer 12 and the negative electrode layer 14. Each component will be described in detail below.

[0017] The positive electrode layer 12 includes an oxygen-evolving electrode, which contains a metal oxide and a metal ion-conducting solid electrolyte. As described above, the electrochemical cell 10 employs a configuration in which the potential difference ΔE with respect to the metal oxide is less than 2.90 V, which has the advantage that the oxygen-evolving electrode does not need to contain an oxygen-evolving catalyst. Therefore, it is preferable that the positive electrode layer 12 and the oxygen-evolving electrode do not contain an oxygen-evolving catalyst.

[0018] The metal oxide is not particularly limited as long as the potential difference ΔE is less than 2.90 V, but it is preferable that it satisfies the preferred range of potential difference ΔE described above. Preferred examples of metal oxides include copper oxides (e.g., CuO and / or Cu) ２ O), and silver oxides (e.g., Ag ２ O ２ and / or Ag ２ O) is one example.

[0019] The metal oxide content in the oxygen-evolving electrode is preferably 10 to 90 parts by volume, more preferably 20 to 80 parts by volume, and even more preferably 40 to 70 parts by volume, when the total amount of metal oxide and metal ion-conducting solid electrolyte contained in the oxygen-evolving electrode is taken as 100 parts by volume.

[0020] Metal ion conductive solid electrolytes are not particularly limited as long as they are solid electrolytes capable of conducting metal ions released from metal oxides during oxygen evolution (reduction reaction). Therefore, preferred examples of metal ion conductive solid electrolytes include copper ion conductive solid electrolytes and silver ion conductive solid electrolytes. Examples of these metal ion conductive solid electrolytes include halogen-based metal ion conductive solid electrolytes, halogen-oxo acid-based metal ion conductive solid electrolytes, and halogen-oxide-based metal ion conductive solid electrolytes. Specifically, an example of a halogen-based metal ion conductive solid electrolyte is RbAg ４ I ５ , Rb ４ Cu １６ I ７ Cl １３ Examples include the following. An example of a halogen-oxo acid-based metal ion conductive solid electrolyte is AgI-Ag ２ CO ３ solid electrolyte, CuI-CuPO ３ Examples include solid electrolyte systems. AgI-Ag ２ CO ３ AgI and Ag in solid electrolyte systems ２ CO ３ The content ratio is 50 to 90 moles of AgI and Ag per 100 moles of the solid electrolyte. ２ CO ３Preferably, the amount is 10 to 50 moles. CuI-CuPO ３ CuI and CuPO in solid electrolyte systems ３ The content ratio is 20 to 60 moles of CuI and CuPO per 100 moles of the solid electrolyte. ３ Preferably, the amount is 40 to 80 moles. An example of a halogen-oxide-based metal ion conductive solid electrolyte is AX-A ２ O-MO ｎ Examples include a solid electrolyte system (where A is Ag and / or Cu, X is at least one selected from the group consisting of F, Cl, Br and I, M is at least one selected from the group consisting of B, Mg, Ca, Sr, Ba, Al, Si, P, V, Cr, Zn, Ga, Ge, As, Se, In, Sn, Sb, Bi, Zr, Hf, Mo and W, and n is a value corresponding to the total valency of M, which may be an integer or a decimal). AX-A ２ O-MO ｎ In solid electrolyte systems, AX, A ２ O and MO ｎ The content ratio is 20 to 80 moles of AX and A per 100 moles of the solid electrolyte. ２ O is 10 to 50 mole parts, and MO ｎ Preferably, it is 5 to 50 mole parts. Preferred AX-A ２ O-MO ｎ The solid electrolyte system is an AgI-Ag, as disclosed in Non-Patent Document 1 (Yusuke Daiko et al., Adv. Eng. Mater. 2018, 20, 1800198) and Non-Patent Document 2 (Supporting Information of Non-Patent Document 1). ２ O-B ２ O ３ Glass (e.g., 60AgI, 25Ag ２ O-15B ２ O ３ (mol %) glass), CuI-Cu ２ O-P ２ O ５ Glass (for example, 33CuI, 33Cu ２ O.34P ２ O ５It may be in the form of glass (mol %) or a molten solid body such as glass. That is, a preferred halogen-oxide metal ion conductive solid electrolyte is AgI-Ag ２ O-B ２ O ３ Solid electrolyte systems and CuI-Cu ２ O-P ２ O ５ It can be a solid electrolyte system.

[0021] The content of the metal ion conductive solid electrolyte in the oxygen generation electrode is preferably 10 to 90 parts by volume, more preferably 20 to 80 parts by volume, and even more preferably 30 to 60 parts by volume, when the total amount of metal oxide and metal ion conductive solid electrolyte contained in the oxygen generation electrode is taken as 100 parts by volume.

[0022] The positive electrode layer 12 (or oxygen generation electrode) preferably further contains an electron conduction aid. On the other hand, in the oxygen generation electrode, a metal oxide and / or metal ion conductive solid electrolyte may also be electron conductive, in which case the positive electrode layer 12 (or oxygen generation electrode) does not need to contain an electron conduction aid. The electron conduction aid that may be included in the positive electrode layer 12 (or oxygen generation electrode) is not particularly limited as long as it is a conductive material, but is preferably a metal and / or conductive carbon, and more preferably conductive carbon. Examples of metals include aluminum, titanium, gold, silver, copper, platinum, chromium, nickel, and combinations thereof. The metal may also include alloys, an example of which is stainless steel. Examples of conductive carbons include acetylene black, carbon black, carbon nanofiber (CNF), carbon fiber (e.g., VGCF® (Vapor Grown Carbon Fiber)), graphite, and combinations thereof.

[0023] When the oxygen-generating electrode contains an electron conduction aid, the content of the electron conduction aid in the oxygen-generating electrode is preferably 1 to 50 parts by volume, more preferably 3 to 30 parts by volume, and even more preferably 5 to 20 parts by volume, when the total amount of metal oxides and metal ion conductive solid electrolytes contained in the oxygen-generating electrode is taken as 100 parts by volume.

[0024] The negative electrode layer 14 is an electrode on which metals derived from metal oxides can be deposited, alloyed with metals derived from metal oxides, or adsorbed metals derived from metal oxides. From these viewpoints, it is preferable that the negative electrode layer 14 contains at least one selected from the group consisting of In, Al, Sn, C, Si, Ca, Sr, Ba, Rh, Ir, Pd, Pt, Au, Zn, Ga, Ge, Pb, Sb, Bi, Cu, Ti, and stainless steel. Examples of electrode materials on which metals derived from metal oxides can be deposited include Cu and stainless steel. Examples of electrode materials that can alloy with metals derived from metal oxides, or that can absorb metals derived from metal oxides, include In, Al, Sn, C, Si, Ca, Sr, Ba, Rh, Ir, Pd, Pt, Au, Zn, Ga, Ge, Pb, Sb, Bi, and Ti, preferably In, Al, Sn, C, Si, Ca, Zn, Pb, Sb, Bi, and Ti, and more preferably In, Al, Sn, Ti, and Si.

[0025] The solid electrolyte layer 16 is composed of a metal ion conductive solid electrolyte. The metal ion conductive solid electrolyte is not particularly limited as long as it is a solid electrolyte capable of conducting metal ions released from metal oxides during oxygen evolution (reduction reaction), similar to the metal ion conductive solid electrolyte described above with respect to the oxygen evolution electrode. Therefore, the description of the metal ion conductive solid electrolyte described above with respect to the oxygen evolution electrode also applies to the solid electrolyte layer 16. The metal ion conductive solid electrolyte contained in the positive electrode layer 12 (oxygen evolution electrode) and the metal ion conductive solid electrolyte constituting the solid electrolyte layer 16 may be made of the same material or different materials, but preferably they are made of the same material.

[0026] As described above, the negative electrode layer 14 may be capable of depositing metal derived from metal oxides. In this case, it is preferable that the negative electrode layer 14 and the solid electrolyte layer 16 are adjacent to each other in such a way that a space is formed between them that allows for the deposition of metal. That is, although the negative electrode layer 14 and the solid electrolyte layer 16 are adjacent to each other, it is preferable that the negative electrode layer 14 and / or the solid electrolyte layer 16 are displaced as metal deposition occurs, forming a space filled with deposited metal on at least a portion of the adjacent surface. Alternatively, it is preferable that the negative electrode layer 14 has a space into which metal derived from metal oxides can be deposited. In this case, the negative electrode layer 14 may be composed of a metal mesh and / or a composite porous body of metal ion conductive solid electrolyte powder and carbon powder. The material of the metal mesh is not particularly limited.

[0027] As shown in Figure 2, the electrochemical cell 10 can be incorporated into an oxygen supply device 20 or an air battery. The oxygen supply device 20 or air battery comprises the electrochemical cell 10 and an outer casing 22. The outer casing 22 has an internal space in which the electrochemical cell 10 is housed. Furthermore, at least a portion of the outer casing 22 has a function or structure that allows oxygen to pass through. Therefore, oxygen generated in the positive electrode layer 12 can be released to the outside by passing through the outer casing 22. In addition, as mentioned above, since the electrochemical cell 10 is an all-solid-state electrochemical cell that does not contain an electrolyte, the oxygen supply device 20 or air battery also has the advantage of not leaking.

[0028] The form of the outer casing 22 is not particularly limited, as long as at least a part of it has a function or structure that allows oxygen to permeate. For example, oxygen release holes 24 may be provided in the outer casing 22 as shown in Figures 2 and 3, or at least a part of the outer casing 22 may be made of an oxygen-permeable material. When oxygen release holes 24 are provided in the outer casing 22, it is preferable that the oxygen release holes 24 be provided in the part facing the positive electrode layer 12 as shown in Figure 2, but it is not limited to this, and may be in any position as long as the oxygen generated in the positive electrode layer 12 can be released to the outside of the outer casing 22.

[0029] The outer casing 22 can be appropriately selected depending on the type of oxygen supply device 20 or air battery. The outer casing 22, oxygen supply device 20, or air battery may be in the form of a coin-type battery as shown in Figures 2 and 3, or in the form of a pouch-type battery. For example, if the oxygen supply device 20 is in the form of a coin-type device as shown in Figures 2 and 3, the outer casing 22 preferably comprises a positive electrode can 22a, a negative electrode can 22b, and a gasket 22c, with the positive electrode can 22a and negative electrode can 22b being crimped together via the gasket 22c to form an internal space. The positive electrode can 22a and negative electrode can 22b can be made of metal such as stainless steel and are not particularly limited. The gasket 22c can be an annular member made of insulating resin such as polypropylene, polytetrafluoroethylene, or PFA resin and is not particularly limited.

[0030] If necessary, a positive electrode current collector layer 26 may be provided between the outer casing 22 and the positive electrode layer 12. A negative electrode current collector layer 28 may also be provided between the outer casing 22 and the negative electrode layer 14. However, the outer casing 22 itself can also function as a current collector. For example, the positive electrode can 22a may function as the positive electrode current collector layer 26, or the negative electrode can 22b may function as the negative electrode current collector layer 28.

[0031] As shown in Figure 5 of the magnetic recording and playback device, the oxygen supply device 20 can be incorporated into the magnetic recording and playback device 30. The magnetic recording and playback device 30 comprises the oxygen supply device 20, at least one magnetic recording medium 32, at least one spacer 34, a spindle motor 36, and at least one magnetic head 38. The spindle motor 36 is a motor for rotating the magnetic recording medium 32. The magnetic head 38 is a head for recording and / or reproducing information on the magnetic recording medium 32. The spacer 34 is a member for fixing the magnetic recording medium 32 to the spindle of the spindle motor 36 and / or for maintaining distance between multiple magnetic recording mediums 32. The oxygen supply device 20 may be located anywhere inside the magnetic recording and playback device 30, as long as it operates normally inside the magnetic recording and playback device 30.

[0032] An example of a magnetic recording and playback device 30 is a hard disk drive (HDD). One recording method for HDDs is heat-assisted magnetic recording (HAMR). In HAMR, there is a mode in which materials such as the protective layer and lubricating layer inside the HDD may decompose due to heat and light, releasing carbon into the atmosphere inside the device, which is then collected at the tip of the near-field optical element, potentially causing failure. To counter this, one could consider introducing oxygen into the HDD to burn off the carbon. However, if oxygen is introduced into a drive sealed with helium, there is a problem that the oxygen will be consumed for purposes other than HAMR protection (for example, oxidation reactions of substances inside the device). Therefore, it is desirable that the initial oxygen concentration be set so that a certain amount of oxygen remains in the drive even as time passes, in accordance with oxygen consumption. On the other hand, if oxygen is consumed over time and the pressure inside the device decreases, the amount of slider levitation may change, which can cause HDI (head disk interface) failure. These problems are successfully resolved by the magnetic recording and playback device 30 equipped with the oxygen supply device 20 of this disclosure. Specifically, in the heat-assisted method, the operating atmosphere may consist of an initial filling of a gas mixture mainly containing He gas and a gaseous oxidizing agent component (oxidizing agent) for the entire operating life of the drive. In this case, long-term reliability can be ensured by sequentially supplying the oxygen consumed by the drive with the oxygen supply device 20, thereby maintaining a constant oxygen concentration in the operating atmosphere. Furthermore, the oxygen supply device 20 of this disclosure can supply oxygen to a sealed HDD while also being shock-resistant to shocks during transport and operation of the magnetic recording and playback device 30.

[0033] In the magnetic recording and playback device 30, an energy-assisted magnetic recording head can be used as the magnetic head 38, which has an energy source (e.g., a heat source such as a laser light source, microwaves, etc.) for assisting magnetization reversal (assisting in writing magnetic signals), a recording element section, and a playback element section. In this way, when the magnetic recording and playback device 30 is an energy-assisted recording system magnetic recording and playback device that includes an energy-assisted magnetic recording head, it is useful as a magnetic recording and playback device with high recording density and high reliability.

[0034] The magnetic recording and playback device 30 may be equipped with an oxygen detection unit that detects the oxygen concentration. The oxygen detection unit can be installed at any position within the device. The oxygen detection unit may include, for example, an oxygen meter for measuring oxygen, or a function for indirectly predicting the amount of oxygen, and can detect the amount of oxygen in the atmosphere inside the magnetic recording and playback device 30 at the time the amount of oxygen needs to be checked.

[0035] The present invention will be further described in detail by the following examples. However, the present invention is not limited to the following examples. In the following examples, the mixing ratio of each component of the oxygen-generating electrode (positive electrode layer) is shown as a volume ratio. This volume ratio corresponds to the volume parts of each component when the total amount of metal oxide and metal ion-conducting solid electrolyte described above is set to 100 volume parts.

[0036] Example 1 (comparison) Li as a metal oxide used in the oxygen generation electrode ２ The fabrication and evaluation of an oxygen supply device using O (potential difference ΔE = 2.91V) were carried out as follows.

[0037] (1) Preparation of solid electrolyte powder Commercially available LiF (lithium fluoride) powder and commercially available AlF ３ (Aluminum fluoride) powder is LiF:AlF ３ The ingredients were weighed and mixed in a 3:1 (molar ratio). The resulting mixture was heated at 900°C and then ground in a mortar to obtain Li ３ AlF ６ A powder (i.e., LAF powder) was obtained. The obtained LAF powder and commercially available Li ２ SiF ６ The powder (i.e., LSF powder) and LAF were weighed together so that the LAF:LSF ratio was 80:20 (molar ratio), and the mixture was mechanically milled using a planetary ball mill to obtain a solid electrolyte powder containing LAF and LSF (hereinafter referred to as LAF-LSF powder) as a lithium-ion conductive solid electrolyte.

[0038] (2) Preparation of cathode powder for oxygen generation electrode (cathode layer) Li in an argon atmosphere having a dew point of -60°C or lower ２O powder (corresponding to a metal oxide), LAF-LSF powder prepared in (1) above, and carbon nanofiber (CNF) (corresponding to an electron conduction aid) are combined with Li ２ The O:LAF-LSF:CNF were weighed out in a volume ratio of 40:60:10, and these were mixed in a dry mortar to obtain the cathode powder.

[0039] (3) Preparation of the negative electrode layer An In metal foil with a thickness of 0.2 mm and a diameter of 16.5 mm was prepared as the negative electrode layer 14.

[0040] (4) Fabrication of the oxygen supply device A coin-shaped oxygen supply device 20, as schematically shown in Figure 2, was fabricated as follows. 165 mg of the LAF-LSF powder fabricated in (1) above was placed in a mold consisting of a resin sleeve with an inner diameter of 16.5 mm and upper and lower punches made of stainless steel, and a solid electrolyte layer 16 was obtained by uniaxial press molding at a pressure of 150 MPa. Subsequently, 136 mg of positive electrode preparation powder was placed on the solid electrolyte layer 16, and a pellet in which the positive electrode layer 12 and the solid electrolyte layer 16 were laminated was fabricated by uniaxial press molding at a pressure of 150 MPa. After press molding of the obtained pellet by heating it at a temperature of 150°C and a pressure of 150 MPa for 12 hours, an In metal foil was bonded to the surface of the solid electrolyte layer 16 opposite to the positive electrode layer 12, and uniaxial press molding was performed at a pressure of 25 MPa. Thus, a pellet with a three-layer structure consisting of a positive electrode layer 12, a solid electrolyte layer 16, and a negative electrode layer 14 was fabricated. The obtained pellet was placed between a positive electrode can 22a and a negative electrode can 22b, which form a CR2032 type coin cell case equipped with oxygen supply holes, and sealed by crimping the positive electrode can 22a and negative electrode can 22b via a gasket 22c. The positive electrode can 22a has seven oxygen release holes 24 formed therein, and is configured to allow oxygen generated in the positive electrode layer 12 to be released to the outside through the oxygen release holes 24. In this way, an oxygen supply device 20 including an all-solid-state electrochemical cell 10 was fabricated. Since this oxygen supply device 20 does not contain any liquid, there is no risk of leakage.

[0041] (5) Evaluation of oxygen evolution The coin-type oxygen supply device 20 produced in (4) above was sealed in a pouch equipped with tab leads, and a constant voltage of 4.38 V was applied for 100 hours to operate the oxygen supply device 20. The presence or absence of oxygen evolution was evaluated by checking whether there was an increase in volume inside the pouch during operation. The evaluation results are as shown in Table 2.

[0042] Example 2 Cu was used as the metal oxide for the oxygen evolution electrode ２ O (potential difference ΔE = 0.76 V) was employed to produce and evaluate an oxygen supply device as follows.

[0043] (1) Preparation of solid electrolyte powder Commercially available CuI powder, commercially available Cu ２ O powder, and commercially available P ２ O ５ powder, CuI:Cu ２ O:P ２ O ５ was weighed so as to have a molar ratio of 33:33:34, placed in a glass tube, heated and melted, then quenched to obtain a melt-solidified product. This melt-solidified product was taken out and pulverized in an alumina mortar to obtain a copper ion conductive solid electrolyte powder.

[0044] (2) Preparation of positive electrode mixture powder for oxygen evolution electrode (positive electrode layer) In an argon atmosphere having a dew point of -60°C or lower, Cu ２ O powder (corresponding to a metal oxide), the copper ion conductive solid electrolyte powder produced in (1) above, and carbon nanofiber (CNF) (corresponding to an electron conduction aid) were mixed, Cu ２ O:copper ion conductive solid electrolyte:CNF was weighed so as to have a volume ratio of 40:60:10, and these were dry-mixed in a mortar to obtain a positive electrode mixture powder.

[0045] (3) Preparation of negative electrode layer A Cu metal mesh having a thickness of 0.2 mm and a diameter of 16.5 mm was prepared as the negative electrode layer 14.

[0046] (4) Production of oxygen supply device A coin-type oxygen supply device 20 as schematically shown in Fig. 2 was produced in the same manner as in Example 1, except that the copper ion conductive solid electrolyte powder produced in (1) above, the positive electrode mixture powder produced in (2) above, and the negative electrode layer produced in (3) above were used.

[0047] (5) Evaluation of oxygen generation Oxygen generation evaluation was performed in the same manner as in Example 1, except that a constant voltage of 1 V was applied to the coin-type oxygen supply device 20 produced in (4) above. The evaluation results were as shown in Table 2. It was also confirmed using an oxygen sensor that oxygen gas was generated.

[0048] Example 3 Ag as a metal oxide used for the oxygen generation electrode ２ O (potential difference ΔE = 0.06 V) was adopted to produce and evaluate an oxygen supply device as follows.

[0049] (1) Preparation of solid electrolyte powder Commercially available AgI powder, commercially available Ag ２ O powder, and commercially available B ２ O ３ powder was weighed such that AgI:Ag ２ O:B ２ O ３ had a molar ratio of 60:25:15, placed in a glass tube, heated to melt, and then quenched to obtain a melted and solidified product. The melted and solidified product was taken out and pulverized in an alumina mortar to obtain a silver ion conductive solid electrolyte powder.

[0050] (2) Preparation of positive electrode compound powder for oxygen generation electrode (positive electrode layer) In an argon atmosphere having a dew point of -60°C or lower, Ag ２ O powder (corresponding to a metal oxide), the silver ion conductive solid electrolyte powder prepared in (1) above, and carbon nanofiber (CNF) (corresponding to an electron conduction auxiliary agent) were mixed, wherein Ag ２ O:silver ion conductive solid electrolyte:CNF was weighed to achieve a volume ratio of 40:60:10, and these were mixed in a dry mortar to obtain positive electrode compound powder.

[0051] (3) Preparation of negative electrode layer A Cu metal mesh having a thickness of 0.2 mm and a diameter of 16.5 mm was prepared as the negative electrode layer 14.

[0052] (4) Production of oxygen supply device A coin-type oxygen supply device 20 schematically shown in FIG. 2 was produced in the same manner as in Example 1, except that the silver ion conductive solid electrolyte powder produced in (1) above, the positive electrode compound powder produced in (2) above, and the negative electrode layer produced in (3) above were used.

[0053] (5) Evaluation of oxygen generation The coin-shaped oxygen supply device 20 fabricated in (4) above was evaluated in the same manner as in Example 1, except that the constant voltage was set to 0.15V. The evaluation results are shown in Table 2. In addition, it was confirmed that oxygen gas was generated using an oxygen sensor.

[0054] Example 4: Cu as a metal oxide used in the oxygen generation electrode ２ The fabrication and evaluation of an oxygen supply device employing O (potential difference ΔE = 0.76V) were carried out as follows.

[0055] (1) Preparation of solid electrolyte powder Commercial CuI powder, commercial CuCl powder, and commercial RbCl powder were weighed so that CuI:CuCl:RbCl was 7:9:4 (molar ratio), sealed in a zirconia container together with zirconia pebbles, and subjected to mechanical milling using a Fritsch planetary ball mill P-6 to obtain copper ion conductive solid electrolyte powder.

[0056] (2) Preparation of positive electrode powder for oxygen generation electrode (positive electrode layer) - In an argon atmosphere having a dew point of -60°C or lower, Cu ２ O powder (corresponding to a metal oxide), the copper ion conductive solid electrolyte powder prepared in (1) above, and carbon nanofiber (CNF) (corresponding to an electron conduction aid) are used in Cu ２ O: Copper ion conductive solid electrolyte: CNF were weighed in a volume ratio of 50:50:10, and these were mixed in a dry mortar to obtain a cathode preparation powder.

[0057] (3) Preparation of the negative electrode layer A Cu metal mesh with a thickness of 0.2 mm and a diameter of 16.5 mm was prepared as the negative electrode layer 14.

[0058] (4) Fabrication of an oxygen supply device A coin-shaped oxygen supply device 20, as schematically shown in Figure 2, was fabricated in the same manner as in Example 1, except that the copper ion conductive solid electrolyte powder fabricated in (1) above, the positive electrode compound powder fabricated in (2) above, and the negative electrode layer fabricated in (3) above were used.

[0059] (5) Evaluation of Oxygen Generation As shown in Figure 4, a voltage-time curve graph was obtained for the coin-shaped oxygen supply device 20 fabricated in (4) above when a constant current of 0.24 mA was applied. From this graph, a plateau region was observed at the theoretical voltage of 0.76 V. Furthermore, the oxygen generation of the coin-shaped oxygen supply device 20 fabricated in (4) above was evaluated in the same manner as in Example 1, except that the constant voltage was set to 1.0 V. The evaluation results are shown in Table 2. In addition, the generation of oxygen gas was confirmed using an oxygen sensor.

[0060]

[0061] 10: Electrochemical cell, 12: Positive electrode layer, 14: Negative electrode layer, 16: Solid electrolyte layer, 20: Oxygen supply device, 22: Outer casing, 22a: Positive electrode can, 22b: Negative electrode can, 22c: Gasket, 24: Oxygen release vent, 30: Magnetic recording and playback device, 32: Magnetic recording medium, 34: Spacer, 36: Spindle motor, 38: Magnetic head

Claims

1. An electrochemical cell that generates oxygen during charging, comprising: a positive electrode layer including an oxygen generating electrode, wherein the oxygen generating electrode comprises a metal oxide and a metal ion conductive solid electrolyte; a negative electrode layer on which a metal derived from the metal oxide can be deposited, alloyed with the metal, or adsorbed; and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, comprising a metal ion conductive solid electrolyte, wherein the oxidative decomposition potential E of the metal oxide １ The metal ions produced by the oxidative decomposition of the metal oxide precipitate as metal at a potential E ２ An electrochemical cell in which the difference ΔE is less than 2.90V.

2. The electrochemical cell according to claim 1, wherein the positive electrode layer further comprises an electron conduction aid.

3. The electrochemical cell according to claim 1, wherein the oxygen-evolving electrode does not contain an oxygen-evolving catalyst.

4. The electrochemical cell according to claim 1, wherein the metal oxide is a copper oxide and the metal ion conductive solid electrolyte is a copper ion conductive solid electrolyte.

5. The electrochemical cell according to claim 1, wherein the metal oxide is silver oxide and the metal ion conductive solid electrolyte is a silver ion conductive solid electrolyte.

6. The electrochemical cell according to claim 2, wherein the electron conduction aid includes conductive carbon.

7. The electrochemical cell according to claim 1, wherein the negative electrode layer and the solid electrolyte layer are adjacent to each other in such a way that a space is formed between them that allows for the deposition of the metal.

8. The electrochemical cell according to claim 1, wherein the difference ΔE is less than 2.0 V.

9. The electrochemical cell according to claim 1, wherein the difference ΔE is less than 1.0 V.

10. An oxygen supply device comprising: an electrochemical cell according to any one of claims 1 to 9; and an outer casing having an internal space, the electrochemical cell being housed within the internal space, wherein at least a portion of the outer casing has a function or structure that allows oxygen to permeate.

11. The oxygen supply device according to claim 10, further comprising a positive electrode current collector layer disposed between the outer casing and the positive electrode layer, and / or a negative electrode current collector layer disposed between the outer casing and the negative electrode layer.

12. An air battery comprising: an electrochemical cell according to any one of claims 1 to 9; and an outer casing having an internal space, the electrochemical cell being housed within the internal space, wherein at least a portion of the outer casing has a function or structure that allows oxygen to permeate.

13. A magnetic recording and reproducing apparatus comprising: an oxygen supply device according to claim 10; at least one magnetic recording medium; at least one spacer; a spindle motor for rotationally driving the magnetic recording medium; and at least one magnetic head for recording and / or reproducing information on the magnetic recording medium.

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