A zinc-selenium battery based on electrolyte-cathode-separator synergistic regulation and a preparation method and application thereof

Abstract

The application discloses a zinc-selenium battery based on electrolyte-cathode-diaphragm synergistic regulation and a preparation method and application thereof, and belongs to the technical field of zinc ion battery materials. The zinc-selenium battery comprises a zinc negative electrode, a selenium-loaded graphene aerogel cathode, an oxidized graphene modified diaphragm and an ionic liquid electrolyte. The ionic liquid electrolyte is prepared by Lewis acid-base reaction of 1-ethyl-3-methyl imidazole chloride salt and zinc chloride; the cathode is prepared by loading selenium on graphene aerogel formed by reduction, freeze-drying and calcination of oxidized graphene; and the diaphragm is prepared by suction filtration of an oxidized graphene layer on the surface of a glass fiber diaphragm, and the coated surface faces the cathode. The application eliminates water molecules by using the ionic liquid electrolyte to broaden the electrochemical window and inhibit the zinc negative electrode side reaction, improves the conductivity by using the graphene aerogel cathode to activate the six-electron transfer reaction, and inhibits the shuttle effect by using the oxidized graphene modified diaphragm to adsorb polyselenides. The battery has an initial capacity of 752 mAh g ‑1 at a current density of 1 A g ‑1 , and still maintains a capacity of 534 mAh g ‑1 after 228 cycles, with a capacity retention rate of 71%. The application has a simple preparation process, low cost, excellent electrochemical performance and good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of zinc-ion battery material technology, specifically relating to a zinc-selenium battery based on the synergistic regulation of electrolyte-positive electrode-separator, its preparation method and application. Background Technology

[0002] With the continued growth of global energy demand and increasing environmental awareness, the development of clean, efficient, and sustainable energy storage technologies has become an urgent need for society today. Rechargeable batteries, as a crucial carrier of clean energy storage, play a key role in portable electronic devices, electric vehicles, and large-scale energy storage systems. Currently, although lithium-ion batteries have achieved commercial application and dominate the market, their high cost, limited lithium resources, and the flammable and explosive nature of organic electrolytes pose safety hazards, limiting their further application in large-scale energy storage.

[0003] Zinc-based water batteries are known for their high theoretical capacity (820 mAh g). -1 With advantages such as low redox potential (-0.76 V vs. SHE), abundant reserves, environmental friendliness, and high safety, it has attracted widespread attention in recent years. However, traditional intercalation cathode materials (such as vanadium-based compounds, manganese-based oxides, and Prussian blue analogues) generally suffer from low energy density and low operating voltage, making it difficult to meet the requirements of high-energy-density energy storage systems. Conversion cathode materials have become a research hotspot due to their multi-electron transfer reactions and high theoretical specific capacity. Chalcogen elements (X) have multiple chemical valence states (X... 2− / X 0 / X 4+ Selenium has become a promising cathode material for high-energy zinc batteries. Zinc-sulfur and zinc-oxygen batteries both exhibit high capacity, but zinc-sulfur batteries have low output voltage and sulfur itself has poor conductivity, while zinc-oxygen-air batteries typically have short cycle lives. Selenium, as a highly promising conversion cathode material, can not only achieve Se... 4+ / Se 2– Six electron transfers, with a theoretical specific capacity as high as 2036 mAh g. −1 Moreover, it has a significantly higher intrinsic conductivity than sulfur. However, zinc selenide batteries still face the following challenges in practical applications: (1) Soluble polyselenides generated during charging and discharging are prone to shuttle effect, migrating to the negative electrode and causing loss of active material and passivation of the negative electrode; (2) The conductivity of selenium and its discharge products still needs to be improved, resulting in slow conversion reaction kinetics; (3) Traditional aqueous systems are difficult to provide a wide electrochemical window, which limits the deep reduction reaction of selenium, and water molecules will exacerbate the dissolution and hydrolysis of polyselenides.

[0004] Currently, researchers have developed various strategies to optimize the performance of zinc-selenium batteries. For example, by using materials such as Cu[Co(CN)6] and CuN3P1@C as selenium supports to catalyze the selenium conversion reaction, the utilization rate of selenium can be improved; or the electrolyte can be modified, and a superhalide anion regulation strategy can be adopted to synergistically regulate the anode interface and selenium conversion intermediates to improve battery life. However, the above strategies often only address local problems and cannot simultaneously solve coupling problems such as multi-selenide shuttle, reaction kinetic lag, and electrolyte side reactions. Moreover, most solutions are still limited by the intrinsic defects of aqueous systems. Therefore, it is urgent to develop novel battery systems from a multi-dimensional synergistic perspective, considering the electrolyte, cathode, and separator, to achieve a comprehensive breakthrough in the electrochemical performance of zinc-selenium batteries. Summary of the Invention

[0005] To address the problems of severe multi-selenide shuttle effect, slow conversion reaction kinetics, and numerous side reactions in aqueous electrolytes in existing technologies, this invention provides a zinc-selenium battery and its preparation method based on the synergistic regulation of electrolyte, cathode, and separator. This battery effectively activates Selenium through the synergistic effect of a non-aqueous ionic liquid electrolyte, a three-dimensional confined selenium / graphene aerogel cathode, and a directionally modified graphene oxide separator. 4+ / Se 2- The deep conversion reaction significantly suppresses polyselenide shuttle and endows the battery with excellent cycle stability and high specific capacity.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: On one hand, the present invention provides a zinc-selenium battery based on the synergistic regulation of electrolyte-positive electrode-separator, including a zinc negative electrode, a selenium-loaded graphene aerogel positive electrode, a graphene oxide modified separator, and an ionic liquid electrolyte.

[0007] Preferably, in the graphene oxide-modified glass fiber membrane, the graphene oxide loading is 3~5 mg / cm³. 2 .

[0008] Preferably, the selenium-loaded graphene aerogel has a selenium mass loading of 60% to 75%.

[0009] Preferably, in the electrolyte, zinc exists mainly in the form of zinc chloride complex anions.

[0010] On the other hand, the present invention provides a method for preparing the above-mentioned zinc-selenium battery, characterized by comprising the following steps: S1. Preparation of ionic liquid electrolyte: Mix 1-ethyl-3-methylimidazolium chloride with zinc chloride at a molar ratio of 1.5 to 1.8, heat and stir at 80 to 110 °C for 8 to 10 h until the solid is completely dissolved, and then cool to room temperature; S2. Preparation of selenium-loaded graphene aerogel cathode: S2-1. Mix graphene oxide dispersion with L-ascorbic acid, wherein the mass ratio of graphene oxide to L-ascorbic acid is 4~6, and react at 60~80 ℃ for 5~12 h to obtain reduced graphene oxide hydrogel. S2-2. After freeze-drying the hydrogel, calcine it at 400~450 ℃ for 1~2 h to obtain a three-dimensional porous graphene aerogel. S2-3. The graphene aerogel is mixed with elemental selenium at a mass ratio of 1:1.5, and heated at 260~600 °C for 10~20 h under a protective atmosphere to obtain selenium-loaded graphene aerogel. S3. Preparation of graphene oxide modified membrane: Graphene oxide is dispersed in deionized water, and the concentration of the dispersion is controlled at 0.15~0.2 mg / mL. After ultrasonic dispersion, it is filtered onto the surface of glass fiber membrane and vacuum dried at 40~60 ℃ for 8~14 h, and the graphene oxide loading is controlled at 3~5 mg / cm². S4. Assemble the battery: Stack the positive electrode, separator, and negative electrode in that order, with the graphene oxide coating of the separator facing the positive electrode. After encapsulation, inject the ionic liquid electrolyte prepared in step S1.

[0011] The advantages of this invention are: 1. A clear three-dimensional synergistic regulation mechanism among electrolyte, cathode, and separator is established: the ionic liquid electrolyte is essentially free of water, effectively broadening the electrochemical stability window and inhibiting zinc anode corrosion and hydrogen evolution; the three-dimensional graphene aerogel provides a highly conductive framework and hierarchical pores, achieving physical confinement and volume expansion buffering of selenium nanoparticles; the graphene oxide coating is oriented towards the cathode, utilizing the strong chemical adsorption and electrostatic shielding effects of oxygen-containing functional groups on polyselenides to construct a directional barrier layer. This synergistic effect of the three components fundamentally solves the problems of shuttle effect and kinetic hysteresis.

[0012] 2. Strong compatibility of preparation process: The synthesis of each component is completed in aqueous phase or under mild thermal conditions, without the need for inert atmosphere protection or complex equipment. The raw material cost is low and it has the potential for large-scale production and industrial application. Attached Figure Description

[0013] Figure 1 Here are SEM images of the graphene aerogel cathode before and after selenium loading in Example 1; Figure 2 The XRD patterns of the graphene aerogel cathode before and after selenium loading in Example 1 are shown. Figure 3 For the zinc-selenium battery in Comparative Example 2 at 1000 mAg -1 Cyclic curves at current density; Figure 4The zinc-selenium battery in Example 1 at 1000 mAg -1 Cyclic curves at current density; Figure 5 For the zinc-selenium battery in Comparative Example 1 at 1000 mAg -1 Charge-discharge curves at different current densities with different numbers of cycles; Figure 6 For the zinc-selenium battery in Comparative Example 2 at 1000 mAg -1 Charge-discharge curves at different current densities with different numbers of cycles; Figure 7 The zinc-selenium battery in Example 1 at 1000 mAg -1 Charge-discharge curves at different current densities with different numbers of cycles; Figure 8 The zinc selenium batteries of Example 1, Comparative Example 1, and Comparative Example 2 were tested at 1000 mAg. -1 Cyclic curves at current density. Detailed Implementation

[0015] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments described below can be arbitrarily combined to form new embodiments.

[0016] Example 1: Zinc-selenium battery based on three-dimensional synergistic regulation of electrolyte-cathode-separator A novel zinc-selenium battery based on three-dimensional synergistic regulation of electrolyte-cathode-separator, the preparation process of which includes the following steps: (1) Preparation of ionic liquid electrolyte: 1-ethyl-3-methylimidazolium chloride (EMImCl) and zinc chloride (ZnCl2) solid in a molar ratio of 1.6 were placed in a sealed container and heated and stirred at 90 °C for 8 h until the solid was completely dissolved to form a uniform and transparent liquid, thus obtaining zinc chloride salt type ionic liquid electrolyte.

[0017] (2) Preparation of selenium-loaded graphene aerogel (GA@Se) cathode: Graphene oxide (GO) was prepared using a modified Hummers method. 40 mg of GO was ultrasonically dispersed in 25 mL of deionized water, and 120 mg of L-ascorbic acid was added. After stirring evenly, the mixture was transferred to a hydrothermal reactor and hydrothermally reacted at 80 °C for 8 h to form a reduced graphene oxide hydrogel. After cooling, the hydrogel was repeatedly washed with deionized water to remove residual reactants, followed by freeze-drying and calcination at 425 °C in an inert atmosphere for 1.5 h to obtain a three-dimensional porous graphene aerogel (GA). The obtained GA was mixed with selenium (Se) powder at a mass ratio of 1:1.5, vacuum-sealed in a quartz tube, and heated at 600 °C for 12 h. After cooling, the selenium-loaded graphene aerogel cathode material (GA@Se) was obtained.

[0018] (3) Preparation of graphene oxide modified membrane: 3.0 mg GO was ultrasonically dispersed in 20 mL of deionized water, filtered, and coated onto the surface of a glass fiber membrane. The membrane was then vacuum dried at 60 °C for 12 h to obtain a graphene oxide loading of 4.0 mg / cm³. 2 The modified diaphragm is denoted as GO@GF diaphragm.

[0019] (4) Battery assembly: In a glove box filled with argon, GA@Se prepared in step (2) is used as the positive electrode, zinc sheet is used as the negative electrode, and GO@GF membrane prepared in step (3) is used as the separator (ensure that the GO coating surface is in close contact with the positive electrode). 100 μL of the ionic liquid electrolyte prepared in step (1) is injected and packaged as a CR2032 button cell. Comparative Example 1: Traditional aqueous zinc-selenium battery (ZSO system) The only difference from Example 1 is that the electrolyte was replaced with a 2.0 M ZnSO4 aqueous solution, and an unmodified ordinary glass fiber membrane was used as the separator. Battery assembly was carried out in air, and the remaining positive and negative electrode materials and assembly sequence were the same as in Example 1. Comparative Example 2: Zinc-selenium batteries containing only ionic liquid electrolytes An ionic liquid-based zinc selenium battery, the preparation process of which includes the following steps: The only difference from Example 1 is that the diaphragm uses an unmodified ordinary glass fiber diaphragm, while the electrolyte (same as step 1 of Example 1), the positive electrode material (same as step 2 of Example 1), and the assembly process are all the same as in Example 1. Morphological and structural characterization: Figure 1 This is a SEM image of the GA load Se before and after Example 1. (From...) Figure 1 It is known that the GA prepared by the present invention has a highly interconnected three-dimensional porous network structure, and the elemental Se is uniformly melted / deposited inside the aerogel pores, effectively realizing the physical confinement of active substances.

[0020] Figure 2 The images show the XRD patterns of GA before and after Se loading in Example 1. Figure 2 It can be seen that the GA@Se composite material exhibits obvious Se characteristic diffraction peaks at positions such as 23.5° and 29.7°, while retaining the broadened carbon peaks of GA, indicating that Se was successfully loaded into the carbon skeleton.

[0021] Electrochemical performance test comparison: The batteries assembled in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to constant current charge-discharge tests on the Land CT2001A testing system, with the voltage window set to 0.01~2.1 V (vs. Zn). 2+ / Zn).

[0022] Figure 3 Comparative Example 2 at 1000 mAg -1 Cycling curves at current density. Test results show that after 40 cycles, the discharge specific capacity of Comparative Example 2 is only 367.5 mAh g⁻¹. -1 .

[0023] Figure 4 Example 1 at 1000 mA g -1 Cycling curves at current density. Test results show that, under the same conditions, the discharge specific capacity of Example 1 stabilizes at 521 mAh g⁻¹ after 40 cycles. -1 .

[0024] Figures 5-7 Comparative Examples 1, 2, and 1 were respectively tested at 1000 mA g. -1 Typical charge-discharge curves at current density. As shown in the figure, the initial reversible capacity of Comparative Example 1 after 3 activation cycles is 900.8 mAh g⁻¹. -1 However, after 40 cycles, the capacity suddenly dropped to 232.5 mAh g. -1 The capacity retention rate was only 25.8%; the initial capacity of Comparative Example 2 was 722.3 mAh g. -1 After 40 laps, the mAh capacity dropped to 367.5 g. -1 The retention rate was 50.8%; while the initial capacity of Example 1 was 668.2 mAh g. -1 It still maintains 521 mAh g after 40 laps -1 The capacity retention rate reached 78.0%.

[0025] Figure 8 For all three at 1000 mA g -1The long-cycle comparison curves were obtained. After 100 cycles, the capacity retention rates of Example 1, Comparative Example 2, and Comparative Example 1 were 71.0%, 62.9%, and 13.8%, respectively, further verifying the structural stability of the system of the present invention during long-term operation.

[0026] Based on the above test data, it can be seen that the present invention significantly improves the overall performance of zinc-selenium batteries through a three-dimensional synergistic regulation mechanism of electrolyte-positive electrode-separator: (1) Non-aqueous ionic liquid electrolyte effectively broadens the electrochemical stability window and basically eliminates the side reactions of hydrogen evolution, corrosion and passivation caused by free water molecules, providing a stable interface environment for the deep redox of selenium. (2) The three-dimensional GA cathode, with its highly conductive network and abundant pores, achieves uniform confinement and volume expansion buffering of Se nanoparticles, thereby activating Se. 2- / Se 4+ Multi-electron conversion reaction significantly improves reversible capacity; (3) GO-modified membrane effectively blocks the migration of active material to the negative electrode through the strong chemical adsorption and size sieving effect of oxygen-containing functional groups on polyselenoides, and greatly suppresses the shuttle effect.

[0027] The synergistic effect of the three components enabled Example 1 to significantly outperform Comparative Examples 1 and 2, which were optimized with a single component, in terms of cycle stability, capacity retention, and coulombic efficiency, thus verifying the superiority and synergistic effect mechanism of the technical solution of the present invention.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A zinc-selenium battery based on synergistic regulation of electrolyte-positive electrode-separator, characterized in that, include: Zinc anode; The positive electrode is a graphene aerogel loaded with selenium, the graphene aerogel having a three-dimensional interconnected porous network structure, in which elemental selenium is confined and distributed in the network pores in the form of nanoparticles. The separator is a graphene oxide modified glass fiber separator, which includes a glass fiber matrix and a graphene oxide layer coated on one side of the matrix, with the graphene oxide layer facing the positive electrode. The electrolyte is an ionic liquid electrolyte prepared by reacting 1-ethyl-3-methylimidazolium chloride with zinc chloride via a Lewis acid-base reaction.

2. The zinc-selenium battery according to claim 1, characterized in that, The molar ratio of 1-ethyl-3-methylimidazolium chloride to zinc chloride is 1.5 to 1.

8.

3. The zinc-selenium battery according to claim 1, characterized in that, The preparation method of the selenium-loaded graphene aerogel includes the following steps: Graphene oxide was reduced with L-ascorbic acid in an aqueous solution to obtain a reduced graphene oxide hydrogel. The reduced graphene oxide hydrogel was freeze-dried and calcined to obtain graphene aerogel. The graphene aerogel was reacted with elemental selenium under a protective atmosphere to obtain a selenium-loaded graphene aerogel.

4. The zinc-selenium battery according to claim 3, characterized in that, The concentration of the graphene oxide dispersion is 1.5~2 mg / mL, the amount of L-ascorbic acid is 6~8 mg / mL, the temperature of the reduction reaction is 60~80 ℃, and the reaction time is 5~12 h.

5. The zinc-selenium battery according to claim 3, characterized in that, The calcination temperature is 400~450℃, and the calcination time is 1~2 h.

6. The zinc-selenium battery according to claim 3, characterized in that, The mass ratio of graphene aerogel to selenium is 1:1.5, the heating reaction temperature is 260~600℃, and the reaction time is 10~20 h.

7. The zinc-selenium battery according to claim 1, characterized in that, In the graphene oxide-modified glass fiber membrane, the graphene oxide loading is 3~5 mg / cm³. 2 The concentration of the graphene oxide dispersion used to prepare the diaphragm is 0.15~0.2 mg / mL.

8. A method for preparing a zinc-selenium battery as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Preparation of ionic liquid electrolyte: Mix 1-ethyl-3-methylimidazolium chloride with zinc chloride at a molar ratio of 1.5 to 1.8, heat and stir at 80 to 110°C for 8 to 10 h until the solid is completely dissolved, and cool to room temperature to obtain ionic liquid electrolyte; S2. Preparation of a selenium-loaded graphene aerogel cathode: The cathode is prepared according to the method described in any one of claims 3 to 6; S3. Preparation of graphene oxide modified membrane: A graphene oxide dispersion with a concentration of 0.15~0.2 mg / mL was filtered onto the surface of a glass fiber membrane and vacuum dried at 40~60 ℃ for 8~14 h to obtain the graphene oxide modified membrane, wherein the graphene oxide loading was 3~5 mg / cm³. 2 ; S4. Assemble the battery: Assemble the battery in the order of positive electrode-separator-negative electrode, so that the graphene oxide coating of the separator is in close contact with the positive electrode, and inject the ionic liquid electrolyte prepared in step S1 after encapsulation.

9. An application of the zinc selenium battery as described in any one of claims 1 to 7 in the field of energy storage.

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