JPS60500190A - electrochemical cell with at least one gas electrode - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] An electrochemical cell gas diffusion electrode with at least one gas electrode has an air electrode. It is used in chlor-alkali cells, fuel cells, metal/air batteries, etc.

Typically, one side of the gas diffusion electrode is in contact with the electrolyte and the other side is in contact with the reactant gas, e.g. contact with air. That is, one side of the gas diffusion electrode faces the gas chamber, e.g. the air chamber. one side facing the electrolyte chamber. However, Swedish patent no. In the battery described in specification No. 7721, the gas chamber and the electrolyte chamber are integrated. , thus one or both sides of the gas diffusion electrode are in contact with the electrolyte and the reactant gas simultaneously. do. The present invention relates to electrochemical cells such as batteries and electrolyzers of this type. , in which at least one side of the electrode is in simultaneous contact with the reactant gas and the electrolyte ( (The following will mainly explain the battery.)

The battery having the gas diffusion electrode described in the above-mentioned Swedish Patent No. 407721 has the following features: The structure is very simple.

Integration of the gas and electrolyte chambers considerably reduces the weight and volume of the battery. It is possible to do. Although this decrease in weight and volume results in a slight increase in resistance value, , this can be offset by a reduction in the weight and volume of the current carrying area.

The present invention provides a surprising improvement in the structure of the battery described in the aforementioned Swedish patent. The feature is that the power density in the electrode area is considerably high.

The present invention also provides improvements in other properties of these electrodes.

As is clear from the term ``gas diffusion electrode,'' these electrodes Mass transfer is an important phenomenon. Optimal gas diffusion electrodes are known, for example, from the Swedish patent no. No. 407721 and No. 360951, etc., but this type of electrode , the rate-limiting factor is the movement of reactants to the reaction sites within the internal area of the gas electrode. It is configured to be.

The amount of catalyst used and the internal surface area should be set somewhat large so that mass transfer becomes the rate-limiting factor. Set to . This setup51 is often based on experimental data, or is based on rational theory. Sophistic thinking may also be of some help. This electrode has a large internal surface area (specific surface area) ) is made in the form of a thin plate.

At the same time, many other requirements must also be met, such as mechanical damage, It is necessary to meet the requirements regarding corrosion resistance, conductivity, etc. Known gas diffusion electrons A common requirement for dissociation is that it is carried out either by movement of the reactants to the reaction site within the object or by self-diffusion. (In addition, internal convection is also added to this. This is because the stagnation reaction (This is because the amount of energy consumed increases.)

Explain the safety of non-invention. Non-invention is the first order.

Secondary batteries such as iron/air batteries, zinc/air batteries, hydrogen/air systems, and metal Tanol/air based fuel cells, electrochemical acid violet generators, alkali metal halides For carrying out electrochemical conversion reactions of gaseous reactants, such as cells for electrolysis of solutions of substances. In a battery having at least one gas electrode, a gas space is provided on each side of the gas electrode 6. The upstream space 11, which is one of the gas spaces, is a reaction gas space. gas supply means 13.14 and the other gas space i.e. the downstream l1111. The space 12 is connected to means 15.16 for discharging the spent reaction gas and thus The used gas is characterized by being passed through a gas electric circle. The present invention relates to a battery having a gas electrode.

Non-invention: Sorry, gas diffusion is not the d or rate-determining step, and in the present invention. This significantly improves battery performance up to its upper limit. This upper limit depends on other properties. For example, it depends on the conductivity, acceptable catalyst concentration, and electrolyte resistance. The value depends on the Next, the present invention will be explained and evaluated under the accompanying drawings. .

FIG. 1 is a diagram with a gas convection electrode for air. This electrode is monopolar This is an example of an electrode. Figure 2 is an explanatory diagram of the structure of the air electrode (air electrode 9) in Figure 1. be. FIG. 6 is an explanatory diagram of an example of a bipolar electrode.

FIG. 4 is an explanatory diagram of a corrugated (corrugated cedar) bipolar electrode. Figure 5 shows the selection FIG. 2 is an illustration of a gas convection electrode provided with a selective gas permeable coating. Figures 6-10 are The method of utilizing the present invention in various known batteries having gas electrodes is mainly shown in FIG. This is a drawing illustrating a method similar to the case of . Figure 11 shows the voltage-current curve. This is the graph shown.

FIG. 1 is a drawing created solely for the purpose of explaining the basic idea. This drawing and other drawings Dimensions shown on the surface are not exact. Furthermore, these drawings show the most masochistic part. This is a schematic diagram showing only the materials. In the first case, the porous electrode 1 is a Swedish patent. This eyelid 1 can be manufactured according to the method described in No. 360952. is mounted in a plastic frame 2 to form an intermediate electrolyte chamber 3.

The intermediate electrolyte chamber 3 is supported by a plastic lid 5, the so-called It has a third leg 4. The new gas convection chamber Toto 6 is based on Swedish Patent No. 407721. It has several members in common with the known gas convection electrode described in No. V'C, and has an air chamber. and an electrolyte chamber. Porous materials used as electrolyte retention members or this is sintered onto the cathode 6. This structure is This is clearly shown in FIG. 2, which is a plan view of a portion of the air electrode.

The second diagram shows the structure of the air electrode 6 in more detail. Nickel wire mesh 8 is supported 5 as members and conductors This is useful for substances with electrochemical catalytic activity (such as Layer 9f consisting of a combination of Raney silver) and polytetrafluoroethylene: hold In the area 10 where the wire mesh 8 and the rig (separator rib) 8 are in contact, The wire mesh is not coated because the rig and electrode are not sufficiently bonded. This is to ensure good contact with the electrolyte.

Figures 1 and 2 show two gas chambers, i.e. one on each side of the electrode. This shows that gas chambers 11 and 12 are present. Continuous electrolyte contact points However, the electrolyte chamber 3, the porous support 1, the separator rib 7, the exposed part of the air electrode 10, The active part 9 of the air electrode exists between the activation parts 9 of the air electrode, and the activation part 9 of the air electrode (film), which also has the property of being gas permeable.

One of the features of the invention is that the gas is transferred from the gas chamber 11 to the exposed portion 9 of the electrode and then transferred to the gas chamber 12. This was done so that it could flow.

The gas (air in this case) is removed by the groove (extraction groove 13 is shown in the drawing). Supply to chamber 11. The waste chamber 11 will be referred to as an "upstream chamber" hereinafter. because This is because it is located on the upstream side of the gas flow path.

The extraction groove 13 is connected to the outer connecting portion 14 via a main groove (not shown). Connection part 14 is shown only in Figure 1.

Gas is discharged from the second gas chamber 12 via the vent groove 15 and the outer connection 16. Contact The sequel 16 is only shown in FIG. The second gas chamber 12 is hereinafter referred to as the "downstream side" It is called a gas chamber.

Gas is thus supplied to this battery system via the connection 14. Next, the removal groove 13 It then enters the gas chamber 11 on the upstream side. The gas then passes through the electrode to the downstream chamber 12. After that, it is discharged through the extraction groove 15 and the connecting part 16.

Also shown in FIG. 1 is the extraction groove 17. The plate groove 17 is arranged at the lower part of the chamber on the downstream side. It will be done. This drainage groove is connected to an outer connection 18 having a valve 19 . This conduit is In particular, it can be used as a downstream discharge means. There is an upper opening in chamber 11 on the upstream side. There is a groove 20, which is connected to an external conduit 21 with a valve 22. This conduit It can be used as a ventilation + stage for the upstream room, and for example, in this specific example, this A selective gas permeable coating is applied to the surface of the electrical conductor facing the upstream chamber.

The electrolyte passes through the drainage groove 23 and enters the electrolyte reservoir 3. The extraction groove 23 is in contact with the outer connection part 24. It is continued. Connection 24 forms part of an external electrolyte thread not shown in the drawings. There's something to do. This external electrolyte thread can be used in surge tanks, heat exchangers, bonders, concentration indicators, etc. It is defined as something that includes an indicator. In this system, U.S. Patent No. 6,801,376 using a circulating electrolyte such as that described in The overflow from the top of the chamber is discharged into the surrounding container.

The other end of the current collector 25 connected to the iron bucket is connected to the main collector 26. It will be done. A current collector 27 is provided at the air electrode by a similar method, and this collector is connected to the main collector 28. In addition, a current collector 29 is connected to the third pole. The other end of this collector is connected to the main collector 30.

As is clear from this description, the example disclosed in Swedish Patent No. 407721 Iron/air batteries made according to conventional technology, such as It would be impossible for a person skilled in the art to go from one to a gas convection type according to the present invention. This variation is not difficult; it can be implemented as follows: By providing a gas electrode with a gas electrode, the upstream area 11]ii and the downstream area 1ill and allow the gas to flow through the electrode by convective motion 1rC. be able to.

In addition, the bipolar type shown in FIG. It is also possible to form electrodes. Created in relation to Figure 2 (Dai-detail map) FIG. 6 shows the partition wall or collector 31 of the two-frame electrode. child The partition wall (′: i is electrically conductive or does not permeate the electrolyte. This partition wall One side (G, in this case, is in contact with the iron pole 1, and the other side is connected to the active layer 5 of the gas electric injection). It will be done. This connection is made via the connecting member 32, i.e. the connecting member 32 is Separate the pole! This is a member that electrically connects to the I wall. Gas comes from chamber 11 on the upstream side It flows into the chamber 12 on the downstream side.

FIG. 4 is a drawing showing a specific example using a corrugated air electrode. Node (node) ) contacts the compartment wall at the contact point 33, and the nodes on the other side contact the compartment wall at the contact point 35. It contacts the palator 34. The gas flows from the upstream chamber 11 to the downstream chamber 12. Ru.

This new gas convection electrode may provide unexpected improvements in battery operation. So, this is very important. Conventional oxidation using alkaline electrolyte/ One of the problems with nitride batteries is that the electrolyte absorbs carbon dioxide from the air. That is true. This electric layer gJ1. is about 50 cycles (reverse number of photodischarges) Therefore, the light should not be replaced! Don't do it. That is, a special scrubber is installed in this system. If not, mixing of the electrolyte must be done after the above cycle. do not have.

Figure 5 illustrates a method to eliminate, or at least significantly improve, this drawback. This is a drawing shown. Blush the electrode facing the upstream chamber, making it selectively permeable. It is coated with a thin film 36 made of a polymer having the following properties. Another in the chamber on the downstream side The above-mentioned selectively permeable thin film (or broken film) is covered with an airtight polymer film 37 around the thorns. ) permeates the oxygen molecules and therefore the oxygen molecules pass through the active area of the air electrode. It can flow into the chamber 12 downstream 11'l.

9 On the other hand, most of the carbon dioxide cannot pass through this membrane and therefore remains in the upstream chamber 12. from there through a drainage groove 20 and a conduit 21 with a valve 22. Le. Gas permeable thin membranes can be manufactured from silicone rubber. This also Licasenate, polyurea, z IJ 7 acetate, various vinyl polymers, It may also be made of cellulose acetate, crosslinked polyglutamine, or the like.

Generally, the thickness of this thin film is less than 1 μm. In order to support this thin film, In order to prevent small holes from forming in this thin film, a backing layer (back layer) is added to this thin film. ing), an example of which is a porous polytetrafluoroethylene A support layer 38 made of tyrene (PTFE) or polysulfone is provided.

In this case, the pressure difference that must be eliminated between the upstream side and the downstream side is small and straightforward. Often, the gas permeation capacity of the thin film is approximately 100 mA/C or less than the actual current density. It is possible to obtain a value corresponding to the amount of i'181 expenses that becomes +++2. Select oxygen only Oxygen in the active area of the electrode is The concentration also increases, which provides better electrode performance.

This technology also eliminates undesirable components in the hydrogen, such as nitrogen and small amounts of carbon dioxide and carbon dioxide. It can also be used to remove elements, which can be carried out using suitable polymers and The same effect can be obtained as in the case of . The appropriate polymer will vary in each case, so experimentation is required. Appropriate selection should be made by conducting laboratory tests.

In order to separate the various gas mixtures within the cell itself, suitable thin film materials and film thicknesses are used. The selection of gas-permeable polymer membranes is based on the current well-developed This is by no means difficult for farmers. As such, this new gas convection current Poles have enabled revolutionary advances in fuel cell and metal/air cell technology. It is a very important member of the

Figures 6-12, made in the same manner as Figure 2, have gas electrodes. 1 is a diagram illustrating how the present invention may be utilized in various batteries. For example, Figure 6 shows the basic structure of a bipolar electrode for a battery that uses phosphoric acid as the electrolyte. be. This structure is a so-called ABA electrode (Angeinara Inciusv). This is an IN that utilizes the present invention in the r1es (n-electrode) developed in soil. just In FIG. 6, only the hydrogen side of this bipolar electrode is shown. The same goes for the air side. However, hydrogen GL] is flowed laterally (transversely) into the air stream. bipolar The impermeable partition wall of the mold electrode 31 consists of densified graphite paper. This partition wall , a carbonized felt structure with micro grooves 40 to promote internal movement of gas 40. It is placed in contact with a member 39 made of a structure. The member 39 is a so-called ABA electrode. The partition wall 31 corresponds to the A1 member, and the partition wall 31 corresponds to the B1 member. According to the invention, member 3 9 can be used as a chamber 11 on the upstream side. Felt structure 391 has gas permeability and at the same time contains a preliminary electrolyte.

In this case, the gas convection electrode 6 is composed of porous carbon paper, but The carbon paper is an electro-catalyst made of noble metal. lyst). The downstream chamber 12 has a felt structure 4 having grooves 41. Contains 0. The felt structure is non-conductive, so this It can be manufactured from PTFE fibers that are resistant to corrosion under chemical environments such as

``This member 41 is in direct contact with a porous structure made of silicon carbide bonded to PTFE. It consists of a layer of matter, which is completely saturated with phosphoric acid. The chamber 12 on the downstream side is a gas couple. It is located between the flow electrode 6 and the electrolyte member 41. Of course, this fuel cell has an extraction groove. , into this vent groove, hydrogen is introduced from the upstream chamber 11 through the gas convection electrode 6 to the downstream side. It is arranged to allow flow into chamber 12. This bipolar electrode air 1lli (a A similar structure is also formed on the ir-side.

FIG. 7 shows one side of a bipolar electrolyte of a fuel cell having a molten acid salt electrolyte according to the present invention. FIG. The so-called electrolyte tile 42 has all ribs 43, and this rib 43 is in contact with the gas convection electrode 6. In this case, the electrode 6 is made of porous nickel oxide. It is an anode.

The partition wall 31 in this case is a corrugated stainless steel plate, which has ribs 44 and This rib 44 is arranged to make electronic contact with the gas convection electrode. upstream The side chamber 11 is formed on one side of the gas convection electrode 6, and the downstream chamber 12 is formed on another side. formed on top of. Similar to the case in Figure 7, another type of bipolar fuel Batteries can also be manufactured. The latter type of battery contains a solid electrolyte; Examples of such materials include ionoconducting oxide-based electrolytes for high-temperature batteries. Or From an on-exchange membrane [for example, the commercially available 'Naflon'' (registered trademark)] It is also possible to produce so-called SPE batteries with an electrolyte of: The actual value of such a battery The manufacturing method is disclosed in U.S. Patent No. 4:175.165. , so-called oxygen generation, which electrochemically concentrates and decomposes oxygen in the air to obtain pure oxygen. Diagram showing biological organs.

It is a surface. This is a generator (has an air electrode (ka-') and an oxygen electrode (anode). do. Oxygen is supplied to one side of the wall 31 between the ribbed separator 46 and the ribbed separator 46. Occurs at the node. The oxygen gas is exhausted through the electrolytic light filling groove 47. Sepa with lip The separator 46 is in contact with another rigged separator 48, and its ribs 49 are in contact with it. A corresponding corrugated gas convection electrode 6 is placed in a pocket in the upper part, and this is connected to the compartment wall. You can keep a close eye on it by pointing it out. Each surface VC-f of the gas convection electrode 6: upstream side The chamber 11 and the downstream chamber 12 are formed. downstream side] and the downstream side If the air in the chamber 12 leaks, the separator is installed in the anode space (anorite space) with a pillar. light space) 16 47, the separator members 46 and 48 have micropores @( mtcro-pcrous) structure.

Figure 9 has an air electrode (anode) configured as a gas convection electrode, 5'i. FIG. 2 is a detailed explanatory diagram of a chloralkali cell. Chlorine gas is a dimensionally stable anode Occurs at 50. The anolyte space 51 is provided with a membrane 53 (for example, a commercially available product). Separated from the space 52 for the Tecasorite by Naflon” (registered trademark), be separated. The space 52 for the cutlight is the chamber 11 on the upstream side and the chamber on the downstream side. 12, and these chambers are separated from each other by air electrodes 6. Upstream chamber 11 contains a member 49 similar to the member 49 shown in FIG. Air @6 is connection member 3 2, it is electronically connected to the partition wall 31.

If a gas convection electrode is used in a metal/air battery, the first Although it is not absolutely necessary to use the so-called third pole shown in the diagram, it is important to note that It is something that should be done. The gas convection electrode is coated with a low acid ultraviolet voltage material (e.g. nickel). However, this coating is applied on the upstream side where oxygen is mainly absorbed during charging. be able to. The gas convection electrode is a two-layer electrode (see Swedish Patent No. 560752). It can also be made in the form of

In this two-layer electrode, the oxygen generation layer is arranged to face the upstream ψ1j. downstream f It is possible to attach similar layers (three-layer electrode). Oxygen The biolayer should be porous so that gas can enter from the upstream side to the downstream side. must be done. Therefore, in this case, the known two-layer gas diffusion electrode The barrier layer used for pillows is completely different from that used for pillows. acid The pores in the outer layer for element generation have a reduced amount of oxygen (reductlon). ) should be more dog than the pores of the layer for.

The present invention (C) such gas convection electrodes also utilize rechargeable metal/air batteries other than iron/air batteries. It can also be used in batteries, such as zinc/air batteries. in the space between two electrodes Since there is no free electrolyte, it depletes toward the air electrode during charging. The tendency to generate light is very low. Therefore, it can be stabilized with various polymers. The zinc electrode, when used in conjunction with the inventive Vcf gas convection electrode, Its cycle life is considerably longer.

If a third electrode is used in a zinc/air battery, the third electrode is By gradually moving the three poles up and down by mechanical means, the third pole can be moved up and down. The amount of dendrites produced can be significantly reduced (Figure 10).

In this case, zinc electrodes in the form of a solution can also be used, which are exposed to the porous material during the charging operation. It is deposited on a thin iron plate 55. Gas convection electrode separator resolution is on the back side of the iron plate 55. come into contact with In this case, the partitioning member in the electrolyte space is a highly porous assimilated 5 (,5intered) It may be made of a polymer plate 516. this Polymer plate/5f3 is an abrasive-containing member (abrasive el, elements) ) f, and this member is connected to the third pole. By this method, the zinc electrode During the charging operation, it is abraded by mechanical means, thereby making it smooth and smooth. The evolution of gas from the third pole, which produces a densified zinc coating, occurs near this third pole. This is facilitated by providing a groove 58 in the separator member 56 of the In this example, the upstream chamber spans the entirety of one side of the electrode to simplify the structure. The downstream chamber is arranged over the entire other side. However The downstream chamber and the upstream chamber ([411] are arranged in sequence on each side of the electrode, and the gas is Flow the electrode back and forth several times from the inlet to the outlet. It is also possiblejL.

This specification cites many technical documents in this field, so if a known battery is However, installing such a gas convection electrode according to the present invention (') should never be done by a black professional. It's difficult (not).

The technical effects of the present invention will be explained. The battery shown in Figure 1 was prepared according to the known method Supply air to both the upstream and downstream sides, and at the same speed. the air is discharged from the upstream chamber 111 and the downstream chamber. In this case, the movement of gas through electric A is not due to convection. Rather, it simply diffuses from both the upstream and downstream sides. The voltage-current curves of a battery operated by the gas diffusion method are shown.

If this air electrode is structured as shown in Fig. 2, the air flow rate can be In the soft experiment, valve 22 was adjusted so that about 50% of the oxygen reacted at the electrode. Almost completely closed, approximately 95% of the introduced air passes through the cathode, while groove 20 and The amount of air discharged through the valve and its connection 21 was approximately 5%. child As is clear from the graph in Figure 11, the charging method of This brought about improvement in the situation.

Another specific softness experiment was also conducted using a 0.6 μm thick cone on the electrode shown in Figure 5. I attached the rubber =d=. In this case, (d) the air flow rate is approximately 6 times the stoichiometric amount. The performance of the electrode is Further improved [curve (C) in Figure 13] significantly less than half of the amount of As is clear from the above explanation, this It is not at all difficult to adjust this to the optimum state for a given field. The convection electrode is generally made somewhat thicker than the diffusion electrode, and the pore size is made larger; It would be better to make the value of the specific surface area even smaller, and make the total surface area a little smaller. electric body It is better to increase the electrolyte content somewhat by satisfying these requirements. Batteries are more durable, have a longer lifespan, and are more durable under abnormal operating conditions. In other words, given these properties, five roughly equivalent gas diffusion electrodes with known gas diffusion electrodes Much better than the properties of batteries. ,・-1jigo・:′,yu；−・,−゛7view3fig. Procedural amendment (formality) November 22, 1982 Commissioner of the Patent Office ４　′　　　′ Relationship to the incident: Patent applicant address full name (Name) Itake-ga (゛Love fI] Lele)! Sodost υ-m 5, correction command date of October 23, 1981 6. Number of inventions increased by amendment 7. Subject of correction Special'、Otsu-Calyx IF'4'r+　3'; Wi-Jinki-Koyoru document; Permission 1:1 Submission of a translation of my written amendment for the names of Yu' and I' Paragraph) Commissioner of the Patent Office 1. Patent application indication paT/5g831004343, patent applicant Address: Nis-18365 Turby, Sweden.

Lawrence Bixbu 14 Name (name) Aktiborag Olle Lindström 4, agent Address: 33 Yumishin Otemachi Building Jinog, 2-2-1 Otemachi, Chiyoda-ku, Tokyo 100 1 5. Date of submission of written amendment: May 14, 1982 8 Amended claims Soil: Primary or secondary batteries such as iron/air batteries, zinc/air batteries, hydrogen/air batteries, and methanol/air fuel cells, electrochemical oxygen generators, alkaline entertainment halo Electrochemical conversion reactions of gaseous reactants, such as cells for the electrolysis of silicide solutions. at least one gas electrode for the reaction, the gas electrode comprising an electrolyte phase; This electrolyte phase is in contact with the counter electrode of the gas electrode and carries the electrocatalyst. In an electrochemical cell containing a gas space (1 1, 12), one of which is a gas space (11), that is, an upstream space. (11) to a continuous supply means of reaction gas, and one other gas space (12) The reaction gas is continuously passed through the gas electrode (6) in contact with the Zunatoro catalyst and electrolyte phase. an electrochemical cell configured to allow the passage of .

2 A request characterized in that the surface of the gas electrode facing the upstream space (11) is The electrochemical cell according to claim 1.

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Claims (1)

[Claims] 11th or secondary batteries such as iron/air batteries, zinc/air batteries, hydrogen/air batteries, and and methanol/air-based fuel cells, electrochemical oxygen generators, alkaline and halogen For electrochemical conversion reactions of gaseous reactants, such as cells for the electrolysis of chemical solutions. in an electrochemical cell in which at least one of the gas electrodes (6) has a sum electrode; A gas space (11, 12) is provided on each side of the (11) That is, the upstream space (11) is connected to the reaction gas supply means (13, 14). Next, the other gas space (12), that is, the downstream space (12), is The reaction gas is connected to the reaction gas discharge means (15, 16) of the gas electrode, and the reaction gas is passed through the gas electrode. An electrochemical cell characterized in that the electrochemical cell is configured to discharge after discharging. 2. Electrification according to claim 1, wherein the gas convection electrode (6) is a monopolar electrode. Academic cell Claim 4, Item 1: The electricity according to claim 4, wherein the gas convection electrode (6) is a bipolar electrode. chemical cellular 4. Claim 1, wherein the gas convection electrode (6) is in contact with an electrolyte in a liquid state. Electrochemical cell according to item 2 or 3. 5. Claim 1, 2, or 5, wherein the gas convection electrode (6) is in contact with a solid electrolyte. Electrochemical cell according to clause 3. 6. The surface of the gas convection electrode facing the upstream space (11) is made of polymer. Claims 1 to 5 covered with a selectively permeable thin film (36) The electrochemical cell described in . 1