Secondary batteries and their manufacturing methods

Abstract

To provide a secondary battery equipped with a low-cost electrode active material containing uranium, capable of generating high electromotive force, and exhibiting excellent charge-discharge characteristics. [Solution] The secondary battery 100 of the present invention comprises a container 101, a partition 102 that divides the inside of the container 101 into a positive electrode chamber 101A and a negative electrode chamber 101B, a positive electrode electrolyte 103 that fills the positive electrode chamber 101A, a negative electrode electrolyte 104 that fills the negative electrode chamber 101B, a positive electrode 105 that contacts the positive electrode electrolyte 103, and a negative electrode 106 that contacts the negative electrode electrolyte 104. The positive electrode electrolyte 103 and the negative electrode electrolyte 104 contain a solvent, an oxidation-reduction pair, and an ionic liquid as a supporting electrolyte, and the oxidation-reduction pair contained in the negative electrode electrolyte 104 is a pair of uranium in valence III and valence IV.

Description

Technical Field

[0001] The present invention relates to a secondary battery and a method for manufacturing the same.

Background Art

[0002] Deteriorated uranium is generated in the manufacturing process of enriched uranium used in nuclear power plants. However, compared with enriched uranium, it is difficult to cause nuclear fission, so there is a problem that it cannot be used as fuel for current nuclear power generation. Although deteriorated uranium is assumed to be used as fuel for a fast reactor, which is an innovative reactor, there is no prospect of practical application, and about 16,000 tons are stored in Japan, and its utilization method is being explored. At present, there is no utilization method of deteriorated uranium other than using it as fuel for a fast reactor in Japan. Considering the current storage amount, it is necessary to quickly find a utilization method for deteriorated uranium.

[0003] A redox flow battery can be cited as a target for utilizing deteriorated uranium. In today's world, viewpoints such as "high safety", "consideration for the environment", "long life", "life cycle cost superiority", "ease of control", and "high degree of design freedom" are emphasized. From such viewpoints, redox flow batteries that utilize vanadium's divalent and trivalent redox pairs and tetravalent and pentavalent redox pairs have attracted attention.

[0004] Regarding redox flow batteries utilizing vanadium, a problem exists in that the reaction on the positive electrode side is a slow reaction involving the desorption and attachment of oxygen ligands, resulting in significant energy loss. Therefore, in order to solve this problem and to utilize depleted uranium, an invention has been made of a redox flow battery that uses a redox pair of uranium with valencies III and IV (Patent Document 1). Specifically, this invention uses a redox pair of uranium with valencies V and VI on the positive electrode side and a redox pair of uranium with valencies III and IV on the negative electrode side. Furthermore, this invention uses a tetraketone (a dimerized β-diketone) as a complexing agent to prevent ligand dissociation and slowing down the reaction during charging and discharging.

[0005] The above invention has the problem of being costly due to the use of a complexing agent. Furthermore, the oxidation-reduction pair on the positive electrode side uses a V-valent and VI-valent uranium pair, and there is room for improvement in terms of generating a higher electromotive force and improving charge-discharge characteristics. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2005-209525 [Overview of the project] [Problems that the invention aims to solve]

[0007] This invention has been made in view of the above circumstances, and aims to provide a secondary battery equipped with a low-cost electrode active material containing uranium, capable of generating a high electromotive force, and having excellent charge-discharge characteristics, as well as a method for manufacturing the same. [Means for solving the problem]

[0008] To solve the above problems, the present invention employs the following means.

[0009] (1) A secondary battery according to one aspect of the present invention comprises a container, a partition that divides the inside of the container into a positive electrode chamber and a negative electrode chamber, a positive electrode electrolyte that fills the positive electrode chamber, a negative electrode electrolyte that fills the negative electrode chamber, a positive electrode that comes into contact with the positive electrode electrolyte, and a negative electrode that comes into contact with the negative electrode electrolyte, wherein the positive electrode electrolyte and the negative electrode electrolyte contain a solvent, an oxidation-reduction pair, and an ionic liquid as a supporting electrolyte, and the oxidation-reduction pair contained in the negative electrode electrolyte is a pair of uranium in valence III and valence IV.

[0010] (2) The secondary battery described in (1) above, comprising: a positive electrode electrolyte tank for storing the positive electrode electrolyte; a positive electrode electrolyte forward flow pipe for flowing the positive electrode electrolyte from the positive electrode chamber to the positive electrode electrolyte tank; a positive electrode electrolyte return flow pipe for flowing the positive electrode electrolyte from the positive electrode electrolyte tank to the positive electrode chamber; and a positive electrode electrolyte flow pump for controlling the flow of the positive electrode electrolyte. The system may further include a negative electrode electrolyte tank for storing the negative electrode electrolyte, a negative electrode electrolyte forward flow piping for flowing the negative electrode electrolyte from the negative electrode chamber to the negative electrode electrolyte tank, a negative electrode electrolyte return flow piping for flowing the negative electrode electrolyte from the negative electrode electrolyte tank to the negative electrode chamber, and a negative electrode electrolyte flow pump for controlling the flow of the negative electrode electrolyte.

[0011] (3) In the secondary battery described in either (1) or (2) above, the cations constituting the ionic liquid are 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1,3-dimethylimidazolium, 1-methyl-3-propylimidazolium, 1-propyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-methyl-3-pentylimidazolium, 1-heptyl-3-methylimidazolium, 1-methyl-3-octylimidazolium, 1-methyl-3-nonylimidazolium, 1-decyl-3-methylimidazolium, 1-dodecyl-3-methylimidazolium, and 1-methyl-3-tetradecyl Preferably, the ionic liquid consists of at least one cation from among imidazolium, 1-hexadecyl-3-methylimidazolium, 1-methyl-3-octadecylimidazolium, tetraethylammonium, tetrabutylammonium, tetraamylammonium, n-octyltrimethylammonium, decyltrimethylammonium, methyltri-n-octylammonium, and didodecyldimethylammonium, and the anions constituting the ionic liquid preferably consist of at least one anion from among fluorine, chlorine, bromine, iodine, dimethyl phosphoric acid, dibutyl phosphoric acid, hexafluorophosphoric acid, tetrafluoroboric acid, and trifluoromethanesulfonic acid.

[0012] (4) In the secondary battery described in any one of (1) to (3) above, it is preferable that the oxidation-reduction pair contained in the positive electrode electrolyte is at least one pair from among divalent and trivalent iron, trivalent and ivvalent iron, divalent and trivalent titanium, trivalent and ivvalent titanium, divalent and trivalent chromium, trivalent and ivvalent chromium, divalent and trivalent manganese, trivalent and ivvalent manganese, divalent and trivalent cobalt, divalent and trivalent nickel, and valent and divalent copper.

[0013] (5) In the secondary battery described in any one of (1) to (4) above, it is preferable that the uranium is either a uranium ion or a uranium complex ion.

[0014] (6) In the secondary battery described in any one of (1) to (5) above, the solvent is an aprotic solvent, and it is preferable that the aprotic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, tetrahydrofuran, dichloromethane, acetonitrile, acetylacetone, trimethyl phosphate, triethyl phosphate, and tributyl phosphate.

[0015] (7) In the secondary battery described in any one of (1) to (6) above, it is preferable that the constituent materials of the positive electrode and the negative electrode are at least one of carbon, platinum, silver, gold, and iron.

[0016] (8) In the secondary battery described in any one of (1) to (7) above, the partition portion is preferably a porous body, and the constituent material of the porous body is preferably at least one of borosilicate glass, alumina, polytetrafluoroethylene resin, perfluoroalkoxy fluororesin, and ion exchange resin.

[0017] (9) In the secondary battery described in any one of (1) to (8) above, it is preferable that neither the positive electrode electrolyte nor the negative electrode electrolyte contains a complexing agent.

[0018] (10) A method for manufacturing a secondary battery according to one aspect of the present invention comprises the steps of: preparing a container whose interior is divided into a positive electrode chamber and a negative electrode chamber by a partition; filling the positive electrode chamber with a positive electrode electrolyte and filling the negative electrode chamber with a negative electrode electrolyte; and bringing the positive electrode into contact with the positive electrode electrolyte and bringing the negative electrode into contact with the negative electrode electrolyte, wherein the positive electrode electrolyte and the negative electrode electrolyte each contain a solvent, an oxidation-reduction pair and an ionic liquid as a supporting electrolyte, and the oxidation-reduction pair of the negative electrode electrolyte is a pair of uranium in valence III and valence IV.

[0019] (11) A method for manufacturing a secondary battery according to another aspect of the present invention is a method of preparing a container whose interior is divided into a positive electrode chamber and a negative electrode chamber by a partition; connecting the positive electrode chamber and a positive electrode electrolyte tank via a positive electrode electrolyte supply flow pipe; connecting the positive electrode chamber and the positive electrode electrolyte tank via a positive electrode electrolyte return flow pipe; attaching a positive electrode electrolyte flow pump to at least one of the positive electrode electrolyte supply flow pipe and the positive electrode electrolyte return flow pipe; connecting the negative electrode chamber and a negative electrode electrolyte tank via a negative electrode electrolyte supply flow pipe; attaching a negative electrode electrolyte flow pump to at least one of the negative electrode electrolyte supply flow pipe and the negative electrode electrolyte return flow pipe; storing positive electrode electrolyte in the positive electrode electrolyte tank and storing negative electrode electrolyte in the negative electrode electrolyte tank The process includes storing the electrolyte, operating the positive electrode electrolyte flow pump to flow the positive electrode electrolyte from the positive electrode electrolyte tank to the positive electrode chamber via the positive electrode electrolyte forward flow pipe, and from the positive electrode chamber to the positive electrode electrolyte tank via the positive electrode electrolyte return flow pipe, respectively, operating the negative electrode electrolyte flow pump to flow the negative electrode electrolyte from the negative electrode electrolyte tank to the negative electrode chamber via the negative electrode electrolyte forward flow pipe, and from the negative electrode chamber to the negative electrode electrolyte tank via the negative electrode electrolyte return flow pipe, respectively, and bringing the positive electrode into contact with the positive electrode electrolyte that has flowed into the positive electrode chamber, and bringing the positive electrode into contact with the negative electrode electrolyte that has flowed into the negative electrode chamber, wherein the positive electrode electrolyte and the negative electrode electrolyte each contain a solvent, an oxidation-reduction pair, and an ionic liquid as a supporting electrolyte, and the oxidation-reduction pair of the negative electrode electrolyte is a pair of uranium in valence III and valence IV.

[0020] (12) In the method for manufacturing a secondary battery described in either (10) or (11) above, it is preferable that neither the positive electrode electrolyte nor the negative electrode electrolyte contains a complexing agent. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a secondary battery that includes a low-cost electrode active material containing uranium, can generate a high electromotive force, and has excellent charge and discharge characteristics, and a method for manufacturing the same.

Brief Description of the Drawings

[0022] [Figure 1] It is a cross-sectional view of a secondary battery according to a first embodiment of the present invention. [Figure 2] It is a cross-sectional view of a secondary battery according to a second embodiment of the present invention. [Figure 3] It is a graph showing the charge and discharge curves of the secondary battery according to Example 1. [Figure 4] It is a graph showing the charge and discharge curves of the secondary battery according to Example 2. [Figure 5] It is a graph showing the charge and discharge curves of the secondary battery according to Example ́3. [Figure 6] It is a graph showing the charge and discharge curves of the secondary battery according to Example 1 after 1 cycle. [Figure 7] It is a graph showing the charge and discharge curves of the secondary battery according to Example 1 after 2 cycles. [Figure 8] It is a graph showing the charge and discharge curves of the secondary battery according to Example 1 after 5 cycles. [Figure 9] It is a graph showing the charge and discharge curves of the secondary battery according to Example 1 after 10 cycles. [Figure 10] It is a graph showing the redox characteristics of the electrode active material according to Experimental Example 1. [Figure 11] It is a graph showing the redox characteristics of the electrode active material according to Experimental Example 2. [Figure 12] It is a graph showing the redox characteristics of the electrode active material according to Experimental Example 3. [Figure 13] It is a graph showing the redox characteristics of the electrode active material according to Experimental Example 4. [Figure 14] It is a graph showing the redox characteristics of the electrode active material according to Experimental Example 5. [Figure 15] It is a graph showing the charge and discharge curves of the secondary battery according to Example 4. [Figure 16]This graph shows the oxidation-reduction properties of the electrode active material related to Experimental Example 6. [Figure 17] This graph shows the oxidation-reduction properties of the electrode active material related to Experimental Example 7. [Modes for carrying out the invention]

[0023] The secondary battery according to an embodiment of the present invention will be described in detail below with reference to the drawings. Note that, for the sake of clarity, the drawings used in the following description may show enlarged versions of key features, and the dimensional ratios of each component may not be the same as those in reality. Furthermore, the materials, dimensions, etc., exemplified in the following description are merely examples, and the present invention is not limited to these; it can be implemented with appropriate modifications without altering its essence.

[0024] <First Embodiment> [Secondary battery] Figure 1 is a cross-sectional view of a secondary battery 100 according to one embodiment of the present invention. The secondary battery 100 mainly comprises a container 101, a partition 102, a positive electrode electrolyte 103, a negative electrode electrolyte 104, a positive electrode (positive electrode) 105, and a negative electrode (negative electrode) 106.

[0025] A partition (diaphragm) 102 is positioned inside the container 101. The inside of the container 101 is divided by the partition 102 into a positive electrode chamber 101A and a negative electrode chamber 101B. The positive electrode chamber 101A is filled with positive electrode electrolyte 103, and the negative electrode chamber 101B is filled with negative electrode electrolyte 104. The inside of the container 101 is configured so that the positive electrode electrolyte 103 and the negative electrode electrolyte 104 do not mix, as is done by the partition 102. At least a portion of the positive electrode 105 is in contact with the positive electrode electrolyte 103. At least a portion of the negative electrode 106 is in contact with the negative electrode electrolyte 104.

[0026] The partition portion 102 is preferably made of a porous material. Any material can be selected as the constituent material of the partition portion 102, but for example, at least one selected from borosilicate glass, alumina, polytetrafluoroethylene resin, perfluoroalkoxy fluororesin, and ion exchange resin may be used. Furthermore, the size (diameter) of the pores formed in the partition portion 102 is preferably 0.1 μm to 5.0 μm.

[0027] The positive electrode electrolyte 103 and the negative electrode electrolyte 104 each contain a solvent, an oxidation-reduction pair, and an ionic liquid as a supporting electrolyte. The ionic liquid is composed of a combination of cations and anions. From the viewpoint of reducing costs, it is preferable that neither the positive electrode electrolyte 103 nor the negative electrode electrolyte 104 contains a complexing agent.

[0028] As the solvent, an aprotic solvent is preferred, and it is preferable to use at least one of the following: dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, tetrahydrofuran, dichloromethane, acetonitrile, acetylacetone, trimethyl phosphate, triethyl phosphate, and tributyl phosphate. In particular, considering the stability of the solvent, it is more preferable to use N,N-dimethylformamide or propylene carbonate.

[0029] The cations that make up ionic liquids include, for example, 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1,3-dimethylimidazolium, 1-methyl-3-propylimidazolium, 1-propyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-methyl-3-pentylimidazolium, 1-heptyl-3-methylimidazolium, 1-methyl-3-octylimidazolium, 1-methyl-3-nonylimidazolium, and 1-decyl-3-methylimidazolium. Preferably, the material consists of at least one of the following cations: zolium, 1-dodecyl-3-methylimidazolium, 1-methyl-3-tetradecylimidazolium, 1-hexadecyl-3-methylimidazolium, 1-methyl-3-octadecylimidazolium, tetraethylammonium, tetrabutylammonium, tetraamylammonium, n-octyltrimethylammonium, decyltrimethylammonium, methyltri-n-octylammonium, and didodecyldimethylammonium.

[0030] The anions constituting the ionic liquid are preferably at least one of the following: fluorine, chlorine, bromine, iodine, dimethyl phosphate, dibutyl phosphate, hexafluorophosphate, tetrafluoroboric acid, and trifluoromethanesulfonic acid.

[0031] The redox pair contained in the negative electrode electrolyte 104 is a pair of tertiary and ivival uranium. This uranium is assumed to be either a uranium ion or a uranium complex ion. The redox pair contained in the positive electrode electrolyte 103 is preferably at least one pair from, for example, tertiary and tertiary iron, tertiary and ivival uranium, tertiary and tertiary titanium, tertiary and ivival uranium uranium, tertiary and ivival uranium, tertiary uranium, tertiary and ivival uranium, tertiary uranium, tertiary and ivival uranium, tertiary uranium, tertiary and ivival uranium, tertiary uranium, tertiary uranium, ter

[0032] The positive electrode 105 consists of a positive electrode current collector 107 and a positive electrode portion 108 held by the positive electrode current collector 107. A positive electrode side external terminal (not shown) electrically connected to the positive electrode current collector 107 is arranged in the container 101. The positive electrode side external terminal and the positive electrode current collector 107 may be provided as a single unit or as separate components.

[0033] The negative electrode 106 consists of a negative electrode current collector 109 and a negative electrode portion 110 held by the negative electrode current collector 109. A negative electrode side external terminal (not shown) electrically connected to the negative electrode current collector 109 is arranged in the container 101. The negative electrode side external terminal and the negative electrode current collector 109 may be provided as a single unit or as separate components.

[0034] Any material can be used for the positive electrode portion 108 and the negative electrode portion 110, but for example, at least one of carbon, platinum, silver, gold, and iron may be used. Considering the stability of the oxidation-reduction reaction and cost, it is preferable to use carbon material for the positive electrode portion 108 and the negative electrode portion 110, and it is even more preferable to use felt-like carbon electrodes in order to increase the reaction efficiency (reaction surface area) of the oxidation-reduction reaction.

[0035] Any material can be used for the positive electrode current collector 107 and the negative electrode current collector 109, but platinum may be used, for example. When the external electrode and the positive electrode current collector 107, and the external electrode and the negative electrode current collector 109 are constructed as separate components, it is preferable from a cost standpoint to use an inexpensive metal or the like as the external electrode.

[0036] [Manufacturing method for secondary batteries] The secondary battery 100 described above can be manufactured mainly through the following steps 1A, 1B, and 1C.

[0037] (1A process) A container 101 is prepared, in which the interior is divided into a positive electrode chamber 101A and a negative electrode chamber 101B by a partition 102.

[0038] (1B process) The positive electrode chamber 101A is filled with the positive electrode electrolyte 103, and the negative electrode chamber 101B is filled with the negative electrode electrolyte 104. It is preferable that the positive electrode chamber 101A and the negative electrode chamber 101B are filled with their respective electrolytes, but as shown in Figure 1, there may be gaps.

[0039] (1C process) The positive electrode 105 (positive electrode portion 108) is brought into contact with the positive electrode electrolyte 103, and the negative electrode 106 (negative electrode portion 110) is brought into contact with the negative electrode electrolyte 104. The positive electrode electrolyte 103 and the negative electrode electrolyte 104 each contain a solvent, a redox pair, and an ionic liquid as a supporting electrolyte. The redox pair of the negative electrode electrolyte is a pair of uranium in valence III and valence IV. Neither the positive electrode electrolyte 103 nor the negative electrode electrolyte 104 may contain a complexing agent.

[0040] As described above, in this embodiment, by using an ionic liquid as the supporting electrolyte included in the electrolyte, a complexing agent is not required, and a uranium secondary battery using uranium as the electrode active material can be realized. The secondary battery of this embodiment can be manufactured at low cost by not including a complexing agent in the electrolyte.

[0041] The secondary battery of this embodiment can generate an electromotive force (voltage between positive and negative electrodes) that is 30-40% higher than conventional uranium secondary batteries that use an electrolyte containing a complexing agent but do not contain an ionic liquid. This effect is very effective in large-scale energy storage systems that suppress voltage fluctuations. In particular, in output-type energy storage systems, there is a problem that the number of cells in series increases in order to increase the output voltage, resulting in a larger size. In contrast, the secondary battery of this embodiment can be used to increase the output voltage per cell. Therefore, for example, the number of cells required to output the same voltage can be reduced, making the energy storage system smaller. It is also possible to increase the output voltage obtained in an energy storage system of the same size.

[0042] The secondary battery of this embodiment, by including an ionic liquid in the electrolyte, exhibits excellent charge-discharge characteristics and can withstand long-term use.

[0043] <Second Embodiment> [Secondary battery] Figure 2 is a cross-sectional view of a secondary battery 200 according to a second embodiment of the present invention. The secondary battery 200 is a redox flow type secondary battery and mainly comprises a container 201, a partition 202, a positive electrode 205, a negative electrode 206, a positive electrode electrolyte tank 213, a positive electrode electrolyte 214, a positive electrode electrolyte forward flow pipe 215, a positive electrode electrolyte return flow pipe 216, a positive electrode electrolyte flow pump 217, a negative electrode electrolyte tank 218, a negative electrode electrolyte 219, a negative electrode electrolyte forward flow pipe 220, a negative electrode electrolyte return flow pipe 221, and a negative electrode electrolyte flow pump 222.

[0044] A partition (diaphragm) 202 is positioned inside the container 201. The inside of the container 201 is divided by the partition 202 into a positive electrode chamber 203 and a negative electrode chamber 204. The positive electrode electrolyte 214 flows in the positive electrode chamber 203, and the negative electrode electrolyte 219 flows in the negative electrode chamber 204. The inside of the container 201 is configured so that the positive electrode electrolyte 214 and the negative electrode electrolyte 219 do not mix, due to the partition 202. At least a portion of the positive electrode 205 is in contact with the positive electrode electrolyte 214. At least a portion of the negative electrode 206 is in contact with the negative electrode electrolyte 219.

[0045] A positive electrode electrolyte supply flow pipe 215, a positive electrode electrolyte return flow pipe 216, and a positive electrode electrolyte flow pump 217 are connected between the positive electrode chamber 203 and the positive electrode electrolyte tank 213.

[0046] The positive electrode electrolyte forward flow pipe 215 connects the positive electrode chamber 203 and the positive electrode electrolyte tank 213, and is configured to allow the positive electrode electrolyte 214 to flow from the positive electrode chamber 203 to the positive electrode electrolyte tank 213. The positive electrode electrolyte return flow pipe 216 connects the positive electrode chamber 203 and the positive electrode electrolyte tank 213, and is configured to allow the positive electrode electrolyte 214 to flow from the positive electrode electrolyte tank 213 to the positive electrode chamber 203. Figure 2 shows the state in which the positive electrode electrolyte 214 is flowing inside the positive electrode electrolyte forward flow pipe 215 and the positive electrode electrolyte return flow pipe 216.

[0047] The positive electrode electrolyte flow pump 217 is connected to at least one of the positive electrode electrolyte supply flow pipe 215 and the positive electrode electrolyte return flow pipe 216, and is configured to control the flow of the positive electrode electrolyte 214.

[0048] Between the negative electrode chamber 204 and the negative electrode electrolyte tank 218, a negative electrode electrolyte supply flow pipe 220, a negative electrode electrolyte return flow pipe 221, and a negative electrode electrolyte flow pump 222 are connected.

[0049] The negative electrode electrolyte supply flow pipe 220 connects the negative electrode chamber 204 and the negative electrode electrolyte tank 218, and is configured to allow the negative electrode electrolyte 219 to flow from the negative electrode chamber 204 to the negative electrode electrolyte tank 218. The negative electrode electrolyte return flow pipe 221 connects the negative electrode chamber 204 and the negative electrode electrolyte tank 218, and is configured to allow the negative electrode electrolyte 219 to flow from the negative electrode electrolyte tank 218 to the negative electrode chamber 204. Figure 2 shows the state in which the negative electrode electrolyte 219 is flowing inside the negative electrode electrolyte supply flow pipe 220 and the negative electrode electrolyte return flow pipe 221.

[0050] The negative electrode electrolyte flow pump 222 is connected to at least one of the negative electrode electrolyte supply flow pipe 220 and the negative electrode electrolyte return flow pipe 221, and is configured to control the flow of the negative electrode electrolyte 219.

[0051] The partition portion 202 has the same configuration as the partition portion 102 of the first embodiment. Furthermore, the positive electrode electrolyte 214 and the negative electrode electrolyte 219 have the same configuration as the positive electrode electrolyte 103 and the negative electrode electrolyte 104 of the first embodiment, respectively. Therefore, the solvent, ionic liquid, and redox pair contained in the positive electrode electrolyte 214 and the negative electrode electrolyte 219 can be those with the same configuration as those contained in the positive electrode electrolyte 103 and the negative electrode electrolyte 104 of the first embodiment, respectively.

[0052] The positive electrode 205 consists of a positive electrode external terminal 207, a positive electrode current collector 208, and a positive electrode portion 209. The positive electrode external terminal 207 is electrically connected to the positive electrode current collector 208 and the positive electrode portion 209. The positive electrode external terminal 207 and the positive electrode current collector 208 may be provided as a single unit or as separate components.

[0053] The negative electrode 206 consists of a negative electrode external terminal 210, a negative electrode current collector 211, and a negative electrode portion 212. The negative electrode external terminal 210 is electrically connected to the negative electrode current collector 211 and the negative electrode portion 212. The negative electrode external terminal 210 and the negative electrode current collector 211 may be provided as a single unit or as separate components.

[0054] The materials for the positive electrode portion 209 and the negative electrode portion 212 can be the same as those used for the positive electrode current collector 107 and the negative electrode current collector 109 in the first embodiment. Any material can be used for the positive electrode external terminal 207, the positive electrode current collector 208, the negative electrode external terminal 210, and the negative electrode current collector 211. However, from a cost perspective, carbon is preferred, and glassy carbon is even more preferred to reduce current collection resistance. When the positive electrode external terminal 207 and the positive electrode current collector 208, and the negative electrode external terminal 210 and the negative electrode current collector 211 are configured as separate components, from a cost perspective, it is desirable to use iron for the positive electrode external terminal 207 and the negative electrode external terminal 210.

[0055] [Manufacturing method for secondary batteries] The secondary battery 200 described above can be manufactured mainly through the following 2A to 2K processes.

[0056] (2A process) A container 201 is prepared, in which the interior is divided into a positive electrode chamber 203 and a negative electrode chamber 204 by a partition 202.

[0057] (2B process) The positive electrode chamber 203 and the positive electrode electrolyte tank 213 are connected via the positive electrode electrolyte supply path flow piping 215.

[0058] (2C process) The positive electrode chamber 203 and the positive electrode electrolyte tank 213 are connected via the positive electrode electrolyte return flow pipe 216.

[0059] (2D process) A positive electrode electrolyte flow pump 217 is attached to at least one of the positive electrode electrolyte supply flow pipe 215 and the positive electrode electrolyte return flow pipe 216.

[0060] (2E process) The negative electrode chamber 204 and the negative electrode electrolyte tank 218 are connected via the negative electrode electrolyte supply flow piping 220.

[0061] (2F process) The negative electrode chamber 204 and the negative electrode electrolyte tank 218 are connected via the negative electrode electrolyte return flow pipe 221.

[0062] (2G process) A negative electrode electrolyte flow pump 222 is attached to at least one of the negative electrode electrolyte supply flow pipe 220 and the negative electrode electrolyte return flow pipe 221.

[0063] (2H process) The positive electrode electrolyte 214 is stored in the positive electrode electrolyte tank 213, and the negative electrode electrolyte 219 is stored in the negative electrode electrolyte tank 218.

[0064] (2I process) The positive electrode electrolyte flow pump 217 is activated to cause the positive electrode electrolyte 214 to flow from the positive electrode electrolyte tank 213 to the positive electrode chamber 203 via the positive electrode electrolyte supply flow pipe 215, and from the positive electrode chamber 203 to the positive electrode electrolyte tank 213 via the positive electrode electrolyte return flow pipe 216.

[0065] (2J process) The negative electrode electrolyte flow pump 222 is activated to cause the negative electrode electrolyte 219 to flow from the negative electrode electrolyte tank 218 to the negative electrode chamber 204 via the negative electrode electrolyte forward flow pipe 220, and from the negative electrode chamber 204 to the negative electrode electrolyte tank 218 via the negative electrode electrolyte return flow pipe 221.

[0066] (2K process) The positive electrode 205 is brought into contact with the positive electrode electrolyte 214 that has flowed into the positive electrode chamber 203, and the negative electrode 206 is brought into contact with the negative electrode electrolyte 219 that has flowed into the negative electrode chamber 204.

[0067] Similar to the first embodiment, the positive electrode electrolyte 214 and the negative electrode electrolyte 219 each contain a solvent, a redox pair, and an ionic liquid as a supporting electrolyte, and the redox pair of the negative electrode electrolyte 219 is a pair of uranium in valence III and valence IV. Alternatively, neither the positive electrode electrolyte 214 nor the negative electrode electrolyte 219 may contain a complexing agent.

[0068] As described above, in this embodiment, by using an ionic liquid as the supporting electrolyte included in the electrolyte, a complexing agent is not required, and a uranium redox flow type secondary battery using uranium as the electrode active material can be realized. The redox flow type secondary battery of this embodiment can be manufactured at low cost by not including a complexing agent in the electrolyte.

[0069] The redox flow type secondary battery of this embodiment can generate an electromotive force (voltage between positive and negative electrodes) that is 30-40% higher than conventional uranium secondary batteries that use an electrolyte containing a complexing agent but do not contain an ionic liquid. This effect is very effective in large-scale energy storage systems that suppress voltage fluctuations. In particular, in output-type energy storage systems, there is a problem that the number of cells in series increases in order to increase the output voltage, resulting in a larger size. In contrast, the secondary battery of this embodiment can be used to increase the output voltage per cell. Therefore, for example, the number of cells required to output the same voltage can be reduced, making the energy storage system smaller. It is also possible to increase the output voltage obtained in an energy storage system of the same size. [Examples]

[0070] The effects of the present invention will be made clearer by the following examples. However, the present invention is not limited to the following examples and can be modified as appropriate without altering its essence.

[0071] (Example 1) A secondary battery was manufactured according to the first embodiment described above. In the positive electrode electrolyte and the negative electrode electrolyte, the solvent was an aprotic solvent consisting of N,N-dimethylformamide, and the supporting electrolyte was an ionic liquid combining 1-ethyl-3-methylimidazolium ions and chloride ions, with a concentration of the supporting electrolyte in the solution of 1 mol / L. In the positive electrode electrolyte, the redox pair was a pair of divalent iron and trivalent iron. The concentration of divalent iron in the positive electrode electrolyte was 0.1 mol / L. In the negative electrode electrolyte, the redox pair was a pair of trivalent uranium and IVvalent uranium. The concentration of IVvalent uranium in the negative electrode electrolyte was 0.1 mol / L. The partition (diaphragm) was a porous body made of borosilicate glass with a pore size of 0.5 μm. The constituent material of the positive electrode current collector and the negative electrode current collector was platinum. The constituent material of the positive electrode part and the negative electrode part was carbon.

[0072] The secondary battery manufactured in Example 1 was charged by holding a current of 3 mA for 900 seconds, and then discharged from this secondary battery at currents of 0 mA, 1 mA, 1.5 mA, and 2 mA. The change in the voltage between the positive and negative electrodes (cell voltage) over time was measured. Figure 3 is a graph showing the results of this measurement. The obtained electromotive force (cell voltage when the discharge current is 0 mA) was approximately 1.3 V, which is significantly higher than the 1.0 V expected as the electromotive force of conventional secondary batteries, as disclosed in Patent Document 1, etc.

[0073] (Example 2) A secondary battery having the same configuration as in Example 1 was manufactured, except that the partition portion was made of a porous material with a pore size of 0.45 μm, which is made of hydrophilic polytetrafluoroethylene.

[0074] (Example 3) A secondary battery having the same configuration as in Example 1 was manufactured, except that the partition portion was made of a porous material with a pore size of 5 μm, which is made of hydrophilic polytetrafluoroethylene.

[0075] The time-dependent change in the positive-negative electrode voltage was measured for the secondary batteries manufactured in Examples 2 and 3 under the same conditions as in Example 1. Figures 4 and 5 are graphs showing the measurement results for the secondary batteries of Examples 2 and 3, respectively. The obtained electromotive force was approximately 1.3V in all cases, showing a high value similar to that of Example 1. From the graphs in Figures 3 to 5, it can be seen that if the discharge current is around 1mA, the output voltage hardly fluctuates even if discharge continues for 1800 seconds.

[0076] A test involving repeated charge and discharge was performed on the secondary battery of Example 1. Specifically, the secondary battery was charged by holding a current of 3 mA for 900 seconds, and then discharged by holding a current of 2 mA for 1200 seconds. This cycle was repeated 10 times. The charge and discharge characteristics were measured after each cycle. Figures 6-9 are graphs showing the measured charge and discharge characteristics after 1 cycle, 2 cycles, 5 cycles, and 10 cycles, respectively. Both the charge and discharge characteristics were almost identical regardless of the number of cycles (number of charge and discharge cycles). From these results, it can be seen that the secondary battery of the present invention exhibits almost no degradation like that seen in the charge and discharge of lithium-ion batteries and can withstand long-term use.

[0077] (Experimental Example 1) To evaluate the redox potential of uranium in combinations of IV and III valencies, a three-electrode cyclic voltammetry method was performed. A glassy carbon component was used as the working electrode, a platinum wire as the counter electrode, and a silver wire as the reference electrode. Each electrode was immersed in a solution containing an aprotic solvent and a supporting electrolyte.

[0078] The aprotic solvent was N,N-dimethylformamide. The supporting electrolyte was an ionic liquid combining 1-ethyl-3-methylimidazolium ions and chloride ions, with a concentration of 1 mol / L of the supporting electrolyte in the solution. Uranium(IV) chloride was further added to the solution to achieve a uranium concentration of 10 mmol / L. Cyclic voltammetry was measured with a sweep rate of 20 mV / s of the potential of the working electrode relative to the counter electrode.

[0079] Figure 10 is a graph showing the measurement results for Experimental Example 1, illustrating the redox characteristics of uranium in its IV and III states, which are the redox pairs on the negative electrode side. When the current density shows a negative peak (reduction peak), uranium in its IV state is reduced to its III state, and when the current density shows a positive peak (oxidation peak), uranium in its III state is oxidized to its IV state. The redox potential is the average value of the potential at the reduction peak and the potential at the oxidation peak. From Figure 10, it can be seen that the redox potentials of uranium in its IV and III states are -1.03V, relative to the redox potentials of silver in its O and I states.

[0080] (Experimental Example 2) To evaluate the redox potential of uranium in combinations of V and VI valencies, three-electrode cyclic voltammetry was performed. These conditions correspond to the evaluation conditions for the redox potential at the positive electrode in Patent Document 1. Cyclic voltammetry was measured in the same manner as in Experimental Example 1, except that uranyl(VI) chloride was added instead of uranium(IV) chloride and the sweep rate of the working electrode potential was set to 50 mV / s.

[0081] (Experimental Example 3) To evaluate the redox potential of copper in both its I and II valencies, three-electrode cyclic voltammetry was performed. The cyclic voltammetry was measured in the same manner as in Experimental Example 1, except that copper(I) chloride was added instead of uranium(IV) chloride, and the copper concentration in the solution was set to 10 mmol / L.

[0082] (Experimental Example 4) To evaluate the redox potential of combinations of II-valent and III-valent iron, three-electrode cyclic voltammetry was performed. Cyclic voltammetry was measured in the same manner as in Experimental Example 1, except that 1-ethyl-3-methylimidazolium tetrachloroferrate, a salt containing III-valent iron, was added instead of uranium(IV) chloride, and the iron concentration in the solution was set to 10 mmol / L.

[0083] Figure 11 is a graph showing the measurement results for Experimental Example 2, illustrating the redox characteristics of uranium with valencies VI and V, which are the redox pairs on the positive electrode side. From Figure 11, it can be seen that the redox potentials of uranium with valencies VI and V are -0.36V, relative to the redox potentials of silver with valencies 0 and I. The theoretical electromotive force of a battery is the difference in redox potentials between the two sets of redox pairs. Therefore, when a secondary battery is constructed with uranium with valencies IV and III as the redox pairs on the negative electrode side and uranium with valencies VI and V as the redox pairs on the positive electrode side, the theoretical electromotive force of that secondary battery is 0.67V.

[0084] Figure 12 is a graph showing the measurement results for Experimental Example 3, illustrating the oxidation-reduction properties of copper in its I and II states, which are the oxidation-reduction pairs on the negative electrode side. From Figure 12, it can be seen that the oxidation-reduction potentials of copper in its I and II states are +0.37V, relative to the oxidation-reduction potentials of silver in its O and I states. Therefore, when a secondary battery is constructed with uranium in its IV and III states as the oxidation-reduction pairs on the negative electrode side and copper in its I and II states as the oxidation-reduction pairs on the positive electrode side, the theoretical electromotive force of that secondary battery will be 1.40V.

[0085] Figure 13 is a graph showing the measurement results for Experimental Example 4, illustrating the redox properties of the II and III valencies of iron, which are the redox pairs on the negative electrode side. From Figure 13, it can be seen that the redox potentials of the II and III valencies of iron are +0.43V, relative to the redox potentials of the O and I valencies of silver. Furthermore, when the IV and III valencies of uranium are used as the redox pairs on the negative electrode side, and the II and III valencies of iron are used as the redox pairs on the positive electrode side, the theoretical electromotive force of the secondary battery is 1.46V.

[0086] By comparing Figures 11 and 12, and Figures 11 and 13, it can be seen that, compared to conventional uranium secondary batteries disclosed in Patent Document 1, etc., a higher electromotive force can be generated by using other materials (in this case, copper and iron) as the redox pair on the positive electrode side. Furthermore, in the secondary battery of the present invention, by including an ionic liquid as the supporting electrolyte in the electrolyte, it is possible to construct a secondary battery with excellent charge-discharge characteristics and electromotive force without the need for a complexing agent.

[0087] (Experimental Example 5) Except for the following differences, cyclic voltammetry was measured in the same manner as in Experimental Example 4: 1-butyl-3-methylimidazolium tetrachloroferate, a salt containing trivalent iron, was added instead of 1-ethyl-3-methylimidazolium tetrachloroferate; the supporting electrolyte was replaced with an ionic liquid combining 1-butyl-3-methylimidazolium ions and chloride ions instead of 1-ethyl-3-methylimidazolium chloride; and the concentration of the supporting electrolyte in the solution was set to 10 mmol / L.

[0088] Figure 14 is a graph showing the measurement results for Experimental Example 5, illustrating the redox properties of the II and III valencies of iron, which are the redox pairs on the negative electrode side. From Figure 14, it can be seen that when the supporting electrolyte is an ionic liquid combining 1-ethyl-3-methylimidazolium ions and chloride ions, the redox potentials of the II and III valencies of iron are +0.43V relative to the redox potentials of the O and I valencies of silver. Also from Figure 14, it can be seen that when the supporting electrolyte is an ionic liquid combining 1-butyl-3-methylimidazolium ions and chloride ions, the redox potentials of the II and III valencies of iron are +0.52V relative to the redox potentials of the O and I valencies of silver. Therefore, when a secondary battery is constructed with an ionic liquid combining 1-butyl-3-methylimidazolium ions and chloride ions as the supporting electrolyte, it is expected that a similar electromotive force can be obtained as when the supporting electrolyte is an ionic liquid combining 1-ethyl-3-methylimidazolium ions and chloride ions.

[0089] (Example 4) A redox flow type secondary battery was manufactured according to the second embodiment described above. In the positive electrode electrolyte and the negative electrode electrolyte, the solvent was an aprotic solvent consisting of propylene carbonate, and the supporting electrolyte was an ionic liquid combining 1-ethyl-3-methylimidazolium ions and chloride ions, with a concentration of the supporting electrolyte in the solution of 1 mol / L. In the positive electrode electrolyte, the redox pair was a pair of divalent iron and trivalent iron. The concentration of divalent iron in the positive electrode electrolyte was 0.1 mol / L. In the negative electrode electrolyte, the redox pair was a pair of trivalent uranium and IVvalent uranium. The concentration of IVvalent uranium in the negative electrode electrolyte was 0.1 mol / L. The partition (diaphragm) was a porous material with a pore size of 0.1 μm made of polytetrafluoroethylene resin. The constituent material of the positive electrode external terminal and the negative electrode external terminal was gold-plated stainless steel. The constituent material of the positive electrode current collector and the negative electrode current collector was carbon.

[0090] The redox flow type secondary battery manufactured in Example 4 was charged by holding a current of 13.5 mA for 60 minutes, and then discharged from this redox flow type secondary battery with a current of 0 mA. It was also charged with a current of 27 mA and then discharged with a current of 2.7 mA. The change in the voltage between the positive and negative electrodes (cell voltage) over time was measured. Figure 15 is a graph showing the measurement results. The obtained electromotive force (cell voltage when the discharge current is 0 mA) remained above 1.4 V for 60 minutes after the start of discharge, significantly exceeding the 1.0 V expected as the electromotive force of conventional secondary batteries, as disclosed in Patent Document 1, etc. Furthermore, it can be seen that if the discharge current is around 2.7 mA, it is possible to discharge while maintaining a cell voltage of 1.4 V or higher for more than 30 minutes.

[0091] (Experimental Example 6) To evaluate the redox potential of uranium in combinations of IV and III valencies, a three-electrode cyclic voltammetry method was performed. A glassy carbon component was used as the working electrode, a platinum wire as the counter electrode, and a silver wire as the reference electrode. Each electrode was immersed in a solution containing an aprotic solvent and a supporting electrolyte.

[0092] A non-protic solvent was used, specifically propylene carbonate. The supporting electrolyte was an ionic liquid combining 1-ethyl-3-methylimidazolium ions and chloride ions, with a concentration of 1 mol / L of the supporting electrolyte in the solution. Uranium(IV) chloride was further added to the solution to achieve a uranium concentration of 10 mmol / L. Cyclic voltammetry was measured with a sweep rate of 10 mV / s of the working electrode potential relative to the counter electrode.

[0093] Figure 16 is a graph showing the measurement results for Experimental Example 6, illustrating the redox characteristics of uranium in its IV and III states, which are the redox pairs on the negative electrode side. When the current density shows a negative peak (reduction peak), uranium in its IV state is reduced to its III state, and when the current density shows a positive peak (oxidation peak), uranium in its III state is oxidized to its IV state. The redox potential is the average of the potential at the reduction peak and the potential at the oxidation peak. From Figure 16, it can be seen that the redox potentials of uranium in its IV and III states are -0.95V, relative to the redox potentials of silver in its O and I states.

[0094] (Experimental Example 7) To evaluate the redox potential of uranium in combinations of IV and III valencies, a three-electrode cyclic voltammetry method was performed. A glassy carbon component was used as the working electrode, a platinum wire as the counter electrode, and a silver wire as the reference electrode. Each electrode was immersed in a solution containing an aprotic solvent and a supporting electrolyte.

[0095] A non-protic solvent was used, specifically propylene carbonate. The supporting electrolyte was an ionic liquid combining tetrabutylammonium ions and chloride ions, with a concentration of 1 mol / L of the supporting electrolyte in the solution. Uranium(IV) chloride was further added to the solution to achieve a uranium concentration of 1 mmol / L. Cyclic voltammetry was measured with a sweep rate of 10 mV / s of the working electrode potential relative to the counter electrode.

[0096] Figure 17 is a graph showing the measurement results for Experimental Example 7, illustrating the redox characteristics of uranium in its IV and III states, which are the redox pairs on the negative electrode side. When the current density shows a negative peak (reduction peak), uranium in its IV state is reduced to its III state, and when the current density shows a positive peak (oxidation peak), uranium in its III state is oxidized to its IV state. The redox potential is the average of the potential at the reduction peak and the potential at the oxidation peak. From Figure 17, it can be seen that the redox potentials of uranium in its IV and III states are -0.58V, relative to the redox potentials of silver in its O and I states. [Explanation of symbols]

[0097] 100, 200... Secondary battery 101, 201...container 101A, 203...Positive electrode chamber 101B, 204...Negative electrode chamber 102, 202... Partition section 103, 214... Positive electrode electrolyte 104, 219...Negative electrolyte 105, 205...Positive electrode 106, 206...Negative electrode 107, 208...Positive electrode current collector 108, 209... Positive electrode section 109, 211...Negative electrode current collector 110, 212...Negative electrode part 207... Positive external terminal 210... Negative external terminal 213... Positive electrode electrolyte tank 215... Positive electrode electrolyte supply path flow piping 216... Positive electrode electrolyte return path flow piping 217... Positive electrode electrolyte flow pump 218... Negative Electrolyte Tank 220...Negative electrode electrolyte supply path flow piping 221...Negative electrode electrolyte return flow piping 222... Negative Electrolyte Flow Pump

Claims

1. Container and The container has a partition that divides the inside into a positive electrode chamber and a negative electrode chamber, The positive electrode electrolyte filling the positive electrode chamber, The negative electrode electrolyte filling the negative electrode chamber, A positive electrode in contact with the positive electrode electrolyte, The system comprises a negative electrode that comes into contact with the negative electrode electrolyte, The positive electrode electrolyte and the negative electrode electrolyte each contain a solvent, an oxidation-reduction pair, and an ionic liquid as a supporting electrolyte. A secondary battery characterized in that the oxidation-reduction pair contained in the negative electrode electrolyte is a pair of uranium in the III and IV states.

2. A positive electrode electrolyte tank for storing the positive electrode electrolyte, A positive electrode electrolyte supply path flow pipe is provided for flowing the positive electrode electrolyte from the positive electrode chamber to the positive electrode electrolyte tank, A return flow pipe for the positive electrode electrolyte flows from the positive electrode electrolyte tank to the positive electrode chamber, A positive electrode electrolyte flow pump controls the flow of the positive electrode electrolyte, A negative electrode electrolyte tank for storing the aforementioned negative electrode electrolyte, A negative electrode electrolyte supply flow pipe is provided for flowing the negative electrode electrolyte from the negative electrode chamber to the negative electrode electrolyte tank, A negative electrode electrolyte return flow pipe is provided for flowing the negative electrode electrolyte from the negative electrode electrolyte tank to the negative electrode chamber, The secondary battery according to claim 1, further comprising a negative electrode electrolyte flow pump for controlling the flow of the negative electrode electrolyte.

3. The cations constituting the aforementioned ionic liquid are 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1,3-dimethylimidazolium, 1-methyl-3-propylimidazolium, 1-propyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-methyl-3-pentylimidazolium, 1-heptyl-3-methylimidazolium, 1-methyl-3-octylimidazolium, 1-methyl-3-nonylimidazolium, and 1-decyl-3-methylimidazolium. It consists of at least one cation from midazolium, 1-dodecyl-3-methylimidazolium, 1-methyl-3-tetradecylimidazolium, 1-hexadecyl-3-methylimidazolium, 1-methyl-3-octadecylimidazolium, tetraethylammonium, tetrabutylammonium, tetraamylammonium, n-octyltrimethylammonium, decyltrimethylammonium, methyltri-n-octylammonium, and didodecyldimethylammonium. The secondary battery according to claim 1, characterized in that the anions constituting the ionic liquid consist of at least one of the anions of fluorine, chlorine, bromine, iodine, dimethyl phosphate, dibutyl phosphate, hexafluorophosphate, tetrafluoroboric acid, and trifluoromethanesulfonic acid.

4. The secondary battery according to claim 1 or 2, characterized in that the oxidation-reduction pair contained in the positive electrode electrolyte is at least one pair from among divalent and trivalent iron, trivalent and ivvalent iron, divalent and trivalent titanium, trivalent and ivvalent titanium, divalent and trivalent chromium, trivalent and ivvalent chromium, divalent and trivalent manganese, trivalent and ivvalent manganese, divalent and trivalent cobalt, divalent and trivalent nickel, and valent and divalent copper.

5. The secondary battery according to either claim 1 or 2, characterized in that the uranium is either a uranium ion or a uranium complex ion.

6. The aforementioned solvent is an aprotic solvent, The secondary battery according to either claim 1 or 2, characterized in that the aprotic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, tetrahydrofuran, dichloromethane, acetonitrile, acetylacetone, trimethyl phosphate, triethyl phosphate, and tributyl phosphate.

7. The secondary battery according to claim 1 or 2, characterized in that the constituent materials of the positive electrode and the negative electrode are at least one of carbon, platinum, silver, gold, and iron.

8. The partition is made of a porous material. The secondary battery according to either claim 1 or 2, characterized in that the constituent material of the porous body is at least one of borosilicate glass, alumina, polytetrafluoroethylene resin, perfluoroalkoxy fluororesin, and ion exchange resin.

9. The secondary battery according to either claim 1 or 2, characterized in that neither the positive electrode electrolyte nor the negative electrode electrolyte contains a complexing agent.

10. The process involves preparing a container in which the interior is divided into a positive electrode chamber and a negative electrode chamber by a partition, The steps include filling the positive electrode chamber with positive electrode electrolyte and filling the negative electrode chamber with negative electrode electrolyte, The process includes bringing the positive electrode into contact with the positive electrode electrolyte and bringing the negative electrode into contact with the negative electrode electrolyte. The positive electrode electrolyte and the negative electrode electrolyte each contain a solvent, an oxidation-reduction pair, and an ionic liquid as a supporting electrolyte. A method for manufacturing a secondary battery, characterized in that the oxidation-reduction pair of the negative electrode electrolyte is a pair of uranium in the III and IV states.

11. The process involves preparing a container in which the interior is divided into a positive electrode chamber and a negative electrode chamber by a partition, A step of connecting the positive electrode chamber and the positive electrode electrolyte tank via a positive electrode electrolyte supply path flow piping, A step of connecting the positive electrode chamber and the positive electrode electrolyte tank via a return flow pipe for the positive electrode electrolyte, A step of installing a positive electrode electrolyte flow pump to at least one of the positive electrode electrolyte supply flow piping and the positive electrode electrolyte return flow piping, A step of connecting the negative electrode chamber and the negative electrode electrolyte tank via a negative electrode electrolyte supply flow piping, A step of connecting the negative electrode chamber and the negative electrode electrolyte tank via a negative electrode electrolyte return flow pipe, A step of attaching a negative electrode electrolyte flow pump to at least one of the negative electrode electrolyte supply flow piping and the negative electrode electrolyte return flow piping, The process involves storing the positive electrode electrolyte in the positive electrode electrolyte tank and storing the negative electrode electrolyte in the negative electrode electrolyte tank. The process involves operating the positive electrode electrolyte flow pump to cause the positive electrode electrolyte to flow from the positive electrode electrolyte tank to the positive electrode chamber via the positive electrode electrolyte supply flow piping, and from the positive electrode chamber to the positive electrode electrolyte tank via the positive electrode electrolyte return flow piping, A step of operating the negative electrode electrolyte flow pump and causing the negative electrode electrolyte to flow from the negative electrode electrolyte tank to the negative electrode chamber via the negative electrode electrolyte supply flow piping, and from the negative electrode chamber to the negative electrode electrolyte tank via the negative electrode electrolyte return flow piping, The process includes bringing the positive electrode into contact with the positive electrode electrolyte that has flowed into the positive electrode chamber, and bringing the positive electrode into contact with the negative electrode electrolyte that has flowed into the negative electrode chamber. The positive electrode electrolyte and the negative electrode electrolyte each contain a solvent, an oxidation-reduction pair, and an ionic liquid as a supporting electrolyte. A method for manufacturing a secondary battery, characterized in that the oxidation-reduction pair of the negative electrode electrolyte is a pair of uranium in the III and IV states.

12. A method for manufacturing a secondary battery according to either 10 or 11, characterized in that neither the positive electrode electrolyte nor the negative electrode electrolyte contains a complexing agent.

Images