Carboxyl polymer-iodine electrode and multi-electron zinc-iodine battery

Abstract

The invention discloses a carboxyl polymer-iodine electrode and a multi-electron zinc-iodine battery, and relates to the field of zinc-iodine batteries, and the carboxyl polymer-iodine electrode is prepared from the following components by weight: 10-20 parts of a carboxyl polymer, 70-80 parts of an iodine-loaded composite material, and 9-11 parts of a conductive agent. The carboxyl polymer is added and can form stable chemical bonds with iodine species (such as I2, I3-and I +) by utilizing the strong nucleophilicity and electronegativity of the carboxyl polymer, shuttling of polyiodide and dissolution of active iodine are effectively inhibited, meanwhile, high-valence iodine (I +) is stabilized through the strong coordination capacity of the carboxyl polymer, efficient proceeding of a four-electron reaction in the zinc-iodine battery is promoted, and the zinc-iodine battery has the advantages of high stability and high efficiency. The carboxyl polymer-iodine electrode is used as a positive electrode, so that the multi-electron zinc-iodine battery capable of realizing four-electron transfer is successfully obtained, and the energy density and the specific capacity of the zinc-iodine battery are improved.

Description

Technical Field

[0001] This application relates to the field of zinc-iodine batteries, and in particular to a carboxyl polymer-iodine electrode and a multi-electron zinc-iodine battery. Background Art

[0002] With the growing global demand for clean energy and efficient energy storage technologies, aqueous zinc-iodine batteries have received extensive attention due to their high energy density, low cost, and high safety.

[0003] Currently, the working principle of aqueous zinc-iodine batteries is usually based on the two-electron reaction of I - / I 2 , with a theoretical specific capacity of 211 mAh / g. In theory, by activating the reaction of high-valent iodine (I + ), the four-electron transfer of I - / I 2 / I + can be achieved, and the specific capacity can be increased to 422 mAh / g.

[0004] However, since I + is extremely prone to hydrolysis in aqueous electrolytes, and the shuttle effect of polyiodides (such as I 3 - ) will cause the loss of active substances and the corrosion of the zinc negative electrode, resulting in a reduction in the actual specific capacity of the zinc-iodine battery. Summary of the Invention

[0005] In view of the deficiencies of the above-mentioned related technologies, this application provides a carboxyl polymer-iodine electrode and a multi-electron zinc-iodine battery. By adding a carboxyl polymer, using its strong nucleophilicity and negative charge, it can form stable chemical bonds with iodine species (such as I 2 , I 3 - , I + ), effectively inhibiting the shuttle of polyiodides and the dissolution of active iodine. At the same time, the strong coordination ability of the carboxyl polymer stabilizes high-valent iodine (I + ), promoting the efficient progress of the four-electron reaction in the zinc-iodine battery. Using the carboxyl polymer-iodine electrode as the positive electrode, a multi-electron zinc-iodine battery with four-electron transfer is successfully obtained, improving the energy density and specific capacity of the zinc-iodine battery.

[0006] In the first aspect, a carboxyl polymer-iodine electrode provided by this application adopts the following technical solution: A carboxyl polymer-iodine electrode is made of components including the following parts by weight: 10-20 parts of carboxyl polymer, 70-80 parts of iodine-loaded composite material, and 9-11 parts of conductive agent.

[0007] Preferably, the carboxyl polymer includes one or more of sodium polyacrylate, sodium polymethacrylate, and carboxymethyl cellulose.

[0008] Preferably, the carboxyl polymer is sodium polyacrylate.

[0009] Preferably, the iodine-loaded composite material is obtained by subjecting carbon nanotubes and iodine to iodine fixation treatment in a weight ratio of 7-9:1.

[0010] Preferably, the iodine-loaded composite material is obtained by subjecting carbon nanotubes and iodine to iodine fixation treatment in a weight ratio of 8:1.

[0011] Preferably, the iodine fixation treatment includes the following steps: mixing the carbon nanotubes and the iodine, and treating them at a temperature of 60-90°C for 3-5 h.

[0012] Preferably, the iodine fixation treatment includes the following steps: mixing the carbon nanotubes and the iodine, and treating them at a temperature of 80°C for 4 h.

[0013] Preferably, the weight ratio of the carboxyl polymer, the iodine-loaded composite material, and the conductive agent is 1:7-9:1.

[0014] Preferably, the weight ratio of the carboxyl polymer, the iodine-loaded composite material, and the conductive agent is 1:8:1.

[0015] Preferably, the conductive agent includes one or more of conductive carbon black, graphene, carbon nanotubes, acetylene black, and Ketjen black.

[0016] Preferably, the conductive agent is conductive carbon black.

[0017] In a second aspect, a preparation method of a carboxyl polymer-iodine electrode provided by the present application adopts the following technical solution: A preparation method of a carboxyl polymer-iodine electrode includes the following steps: mixing and grinding an iodine-loaded composite material, a carboxyl polymer, and a conductive agent, adding water to obtain a mixed slurry, and coating the mixed slurry on a current collector to prepare the carboxyl polymer-iodine electrode.

[0018] In a third aspect, a multi-electron zinc-iodine battery provided by the present application adopts the following technical solution: A multi-electron zinc-iodine battery includes a carboxyl polymer-iodine electrode, a negative electrode, an electrolyte, and a separator, and the carboxyl polymer-iodine electrode is a positive electrode.

[0019] Preferably, the electrolyte includes a zinc sulfate solution with a concentration of 0.9-1.1 mol / L.

[0020] Preferably, the electrolyte includes a zinc sulfate solution with a concentration of 1 mol / L.

[0021] Preferably, the separator includes one or more of a glass fiber separator, a polypropylene separator, and a polyethylene separator.

[0022] Preferably, the separator is a glass fiber separator.

[0023] In summary, the present application includes at least one of the following beneficial technical effects: 1. By adding a carboxyl polymer, utilizing its strong nucleophilicity and negative charge, it can form stable chemical bonds with iodine species (such as I 2 , I 3 - , I + ), effectively inhibiting the shuttle of polyiodides and the dissolution of active iodine. At the same time, the carboxyl polymer's strong coordination ability stabilizes high-valent iodine (I + ), promoting the efficient progress of the four-electron reaction in the zinc-iodine battery. Using the carboxyl polymer-iodine electrode as the positive electrode, a multi-electron zinc-iodine battery with four-electron transfer is successfully achieved, improving the energy density and specific capacity of the zinc-iodine battery; 2. The carboxyl polymer-iodine electrode of the present application as the positive electrode of the zinc-iodine battery can trigger a highly reversible four-electron redox reaction of I - being oxidized to I + . At the same time, the electrode potential of the zinc-iodine battery is expanded from 1.3 V (vs. Zn / Zn 2+ ) to 1.9 V (vs. Zn / Zn 2+ ), and the specific capacity reaches 346 mAh / g; 3. When the carboxyl polymer-iodine electrode of the present application is used as the positive electrode of the zinc-iodine battery, an electrolyte with a low concentration (zinc sulfate solution with a concentration of 0.8 - 1.2 mol / L) can trigger a stable zinc-iodine four-electron reaction, improving the applicable range of the carboxyl polymer-iodine electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a comparison chart of cyclic voltammograms of the multi-electron zinc-iodine battery in Example 1 at different scan rates.

[0025] Figure 2 is the cyclic voltammogram of the zinc-iodine battery in Comparative Example 1.

[0026] Figure 3 is the cyclic voltammogram of the zinc-iodine battery in Comparative Example 2.

[0027] Figure 4 is a comparison chart of discharge curves of the multi-electron zinc-iodine battery in Example 1 and the zinc-iodine batteries in Comparative Examples 1 - 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present application is further described in detail below in conjunction with examples. The following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. In the following examples, if specific conditions are not specified, they are carried out according to normal conditions or conditions recommended by the manufacturer. The methods used are conventional methods known in the art unless otherwise specified, and the consumables and reagents used are commercially available unless otherwise specified. Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the recorded content may also be applied to the present invention. The raw materials used in the embodiments and comparative examples can be obtained commercially.

[0029] Preparation Example 1 Example 1 of the present application provides a carboxyl polymer-iodine electrode, which is prepared by the following method: 8 parts by weight of carbon nanotubes and 1 part by weight of iodine were mixed, placed in a reactor, the temperature was controlled to 80°C, and the treatment was performed for 4 hours to obtain an iodine-loaded composite material. 8 parts by weight of the iodine-loaded composite material, 1 part by weight of the carboxyl polymer and 1 part by weight of the conductive agent were mixed and fully ground, ultrapure water was added and ground again to obtain a mixed slurry, which was in a black paste state. The mixed slurry was coated on a current collector to prepare a carboxyl polymer-iodine electrode.

[0030] In this preparation example, the carboxyl polymer is sodium polyacrylate (M W The conductive agent is conductive carbon black (Super P).

[0031] Example 1 Example 2 of the present application provides a multi-electron zinc-iodine battery, which is prepared by the following method: A multi-electron zinc-iodine battery was assembled using a carboxyl polymer-iodine electrode as the positive electrode, a zinc sheet as the negative electrode, a glass fiber separator to separate the positive and negative electrodes, and 1 mol / L zinc sulfate as the electrolyte.

[0032] Comparative Example 1 Comparative Example 1 provides a zinc-iodine battery, which is prepared by the following method: 8 parts by weight of carbon nanotubes and 1 part by weight of iodine were mixed, placed in a reactor, and the temperature was controlled at 80°C for 4 hours to obtain an iodine-loaded composite material. 8 parts by weight of the iodine-loaded composite material, 1 part by weight of polyvinylidene fluoride and 1 part by weight of conductive carbon black (Super P) were mixed and fully ground, and N-methylpyrrolidone (NMP) was added and ground again to obtain a mixed slurry, which was a black paste. The mixed slurry was coated on the current collector to prepare a polyvinylidene fluoride-iodine electrode.

[0033] Using a polyvinylidene fluoride-iodine electrode as the positive electrode and a zinc sheet as the negative electrode, a glass fiber separator is used to separate the positive and negative electrodes, and 1 mol / L zinc sulfate is used as the electrolyte to assemble a zinc-iodine battery.

[0034] Comparative Example 2 Comparative Example 2 provides a zinc-iodine battery prepared by the following method: Mix 8 parts by weight of carbon nanotubes and 1 part by weight of iodine, place them in a reaction kettle, control the temperature at 80 °C, and treat for 4 h to obtain an iodine-loaded composite material. Take 8 parts by weight of the iodine-loaded composite material, 1 part by weight of 2-acrylamido-2-methylpropanesulfonic acid sodium salt, and 1 part by weight of conductive carbon black (Super P), mix and grind them thoroughly, add water to obtain a mixed slurry, and the mixed slurry is a black paste. Coat the mixed slurry on the current collector to prepare a sulfonic acid group-iodine electrode.

[0035] Using the sulfonic acid group-iodine electrode as the positive electrode and a zinc sheet as the negative electrode, a glass fiber separator is used to separate the positive and negative electrodes, and 1 mol / L zinc sulfate is used as the electrolyte to assemble a zinc-iodine battery.

[0036] Test and detection (1) Respectively detect the cyclic voltammetry characteristic curves of the multi-electron zinc-iodine battery of Example 1 at scan rates of 1 mV / s, 2 mV / s, 5 mV / s, and 10 mV / s to obtain a comparison chart of cyclic voltammograms at different scan rates, as Figure 1 shown.

[0037] (2) Detect the cyclic voltammetry characteristic curve of the zinc-iodine battery of Comparative Example 1 at a scan rate of 5 mV / s, as Figure 2 shown.

[0038] (3) Detect the cyclic voltammetry characteristic curve of the zinc-iodine battery of Comparative Example 2 at a scan rate of 5 mV / s, as Figure 3 shown.

[0039] (4) Detect the discharge curves of the multi-electron zinc-iodine battery of Example 1 and the zinc-iodine batteries of Comparative Examples 1-2 to obtain a comparison chart of discharge curves as Figure 4 shown, where the discharge curve of the multi-electron zinc-iodine battery of Example 1 is marked as PAA-Na, the discharge curve of the zinc-iodine battery of Comparative Example 1 is marked as PVDF, and the discharge curve of the zinc-iodine battery of Comparative Example 2 is marked as PAMPS-Na.

[0040] Result analysis The following will Figures 1-4 be described in detail with reference to the experimental data provided.

[0041] Refer to Figure 1, The cyclic voltammetry curves show that, at a scanning rate of 1 - 10 mV / s, for the multi - electron zinc - iodine battery of Example 1 using the carboxyl polymer - iodine electrode of Preparation Example 1 as the positive electrode, two obvious and stable pairs of redox peaks appear in the charge - discharge range of 1 - 2V, located near 1.4V and 1.8V respectively. This indicates that the electro - chemical reaction of the multi - electron zinc - iodine battery of Example 1 has high reversibility in the charge - discharge range of 1 - 2V, with good reaction kinetics and stable battery performance. That is, the multi - electron zinc - iodine battery of Example 1 has successfully achieved the stable promotion of the four - electron reaction at a low electrolyte concentration (1mol / L zinc sulfate). While referring to Figure 2 and Figure 3 , Figure 2 show that the zinc - iodine battery of Comparative Example 1 only has a pair of redox peaks near 1.4V, while Figure 3 shows that the zinc - iodine battery of Comparative Example 2 only has a pair of redox peaks near 1.3V, indicating that the zinc - iodine batteries of Comparative Example 1 and Comparative Example 2 can only achieve a two - electron transfer process. It is analyzed that it may be because there is sodium polyacrylate with nucleophilicity in the carboxyl polymer - iodine electrode of the multi - electron zinc - iodine battery of Example 1, which enables the active substance iodine to not only be converted into iodide ions with a valence of - 1, but also react with the carboxylate groups in the carboxyl polymer, inducing the iodine element to change to a valence of + 1, thus realizing the four - electron transfer process, and the theoretical specific capacity reaches 422 mAh / g. In Comparative Example 1 and Comparative Example 2, in the absence of carboxylate groups, only a two - electron transfer process can be achieved, and the theoretical specific capacity is only 211 mAh / g. It is analyzed that it may be because there is no nucleophilic reagent in Comparative Example 1, and the nucleophilicity of the sulfonate group in Comparative Example 2 is weak, making it difficult to provide sufficient electron interaction to promote the stability of I + .

[0042] Referring to Figure 4 , it can be seen that there is only a low - voltage plateau near 1.4V in the discharge curves of the zinc - iodine batteries of Comparative Example 1 and Comparative Example 2, corresponding to the conversion reaction of I - / I 0 . In the discharge curve of the multi - electron zinc - iodine battery of Example 1, there are discharge plateaus near both 1.4V and 1.8V. The discharge plateau near 1.8V corresponds to the conversion reaction of I 0 / I + . This result is consistent with the result of the cyclic voltammetry characteristic curve of Figures 1-3 . And the specific capacities of the multi - electron zinc - iodine battery of Example 1, the zinc - iodine battery of Comparative Example 1, and the zinc - iodine battery of Comparative Example 2 are 346, 140, and 170 mAh / g respectively. The specific capacity of the multi - electron zinc - iodine battery of Example 1 is more than twice that of the zinc - iodine batteries of Comparative Example 1 and Comparative Example 2. This shows that the multi - electron zinc - iodine battery of Example 1 can stably promote the four - electron reaction and greatly improve the specific capacity of the zinc - iodine battery.

[0043] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A carboxyl polymer-iodine electrode, characterized in that: The invention is prepared from the following components in parts by weight: 10-20 parts of carboxyl polymer, 70-80 parts of iodine-carrying composite material and 9-11 parts of conductive agent.

2. A carboxyl polymer-iodine electrode according to claim 1, characterized in that: The carboxyl polymer includes one or more of sodium polyacrylate, sodium polymethacrylate, and carboxymethyl cellulose.

3. A carboxyl polymer-iodine electrode according to claim 1, characterized in that: The iodine-loaded composite material is obtained by subjecting carbon nanotubes and iodine element to iodine fixation treatment in a weight ratio of 7-9:

1.

4. A carboxyl polymer-iodine electrode according to claim 3, characterized in that: The iodine fixation treatment comprises the following steps: The carbon nanotubes and the iodine element are mixed and treated at a temperature of 60-90° C. for 3-5 hours.

5. A carboxyl polymer-iodine electrode according to claim 1, characterized in that: The weight ratio of the carboxyl polymer, the iodine-loaded composite material and the conductive agent is 1:7-9:

1.

6. A carboxyl polymer-iodine electrode according to claim 5, characterized in that: The conductive agent includes one or more of conductive carbon black, graphene, carbon nanotubes, acetylene black and Ketjen black.

7. A method for preparing a carboxyl polymer-iodine electrode according to any one of claims 1 to 6, characterized in that: The following steps are involved: The iodine-loaded composite material, carboxyl polymer and conductive agent are mixed and ground, and then water is added to obtain a mixed slurry. The mixed slurry is coated on a current collector to prepare the carboxyl polymer-iodine electrode.

8. A multi-electron zinc-iodine battery, characterized in that: The invention comprises the carboxyl polymer-iodine electrode according to any one of claims 1 to 6, a negative electrode, an electrolyte and a separator, wherein the carboxyl polymer-iodine electrode is a positive electrode.

9. A multi-electron zinc-iodine battery according to claim 8, characterized in that: The electrolyte includes a 0.9-1.1 mol / L zinc sulfate solution.

10. A multi-electron zinc-iodine battery according to claim 8, characterized in that: The diaphragm includes one or more of a glass fiber diaphragm, a polypropylene diaphragm, and a polyethylene diaphragm.

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