An azo-based organic zinc-ion battery, a preparation method and a recycling method

Abstract

The application discloses an azo organic zinc ion battery, a preparation method and a recycling method. The positive active material of the azo organic zinc ion battery is azobenzene or a functional group-substituted azobenzene, the loading amount of the positive active material is 5-40 mg / cm 2 , the negative electrode is a zinc-based material, and the solute in the aqueous electrolyte is a zinc salt. The recycling method comprises the following steps: placing a positive electrode sheet into an organic solvent, stirring or ultrasonic treating, filtering, removing the solvent under vacuum or obtaining the recycled azobenzene or functional group-substituted azobenzene after the solvent is volatilized, and obtaining the conductive additive again after the filter cake is treated with acid and carbonization. The azobenzene or functional group-substituted azobenzene which can be recycled is used as a small-molecule organic positive active material, high capacity and excellent cycle performance are realized under the condition of high loading amount, and the organic material can be recycled through a simple extraction method, so that the technical problems of low loading amount of an organic electrode and lack of recycling of battery organic materials are solved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and more specifically, relates to an azo-type organic zinc-ion battery, its preparation method, and its recycling method. Background Technology

[0002] Rechargeable batteries have driven the global energy transition towards a sustainable energy system. Demand for lithium-ion batteries is expected to increase significantly in the coming years, but the scarcity and rising price of lithium resources severely hinder their large-scale application. In recent years, various non-lithium-based batteries have seen substantial development. Among them, aqueous zinc-ion batteries have attracted increasing attention due to their advantages such as low redox potential (-0.76V vs. SHE), high specific capacity, and low cost. However, some transition metal-based inorganic electrode materials (manganese, vanadium-based oxides, and Prussian blue analogues) often exhibit poor cycle performance in zinc-ion batteries and cause serious environmental pollution. Therefore, we need to find alternatives to achieve sustainable battery chemistry.

[0003] In recent years, the application of organic materials in the energy storage field has received increasing attention. Besides being environmentally friendly, organic materials offer many advantages as electrode materials, such as: their wide availability, simple and low-cost synthesis; their flexible structures, which support the smooth insertion / extraction of large or multivalent ions, facilitating stable cycling; and the ability to design the structure of organic molecules to achieve desired high-performance organic electrode materials. Given these potential advantages, significant efforts have been made over the past few decades to utilize these redox-active organic materials as electrode active materials.

[0004] It is worth noting that although organic electrodes have high specific capacity (mAh / g), the vast majority of reported organic electrodes have low loading (below 3 mg / cm³). 2 This leads to the areal capacity (mAh / cm²) of organic batteries. 2 The loading level is too low to meet commercialization requirements (active material loading greater than 10 mg / cm³). 2 More importantly, while the sustainability of redox-active organic materials is widely discussed, there is still a lack of reports on the recycling of organic materials. Therefore, developing a high-capacity and recyclable organic zinc-ion battery is crucial for the development of sustainable energy storage batteries. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides an azo-based organic zinc-ion battery, its preparation method, and its recycling method. The aim is to use recyclable azobenzene or functionally substituted azobenzene as a small-molecule organic positive electrode active material, with a loading greater than 10 mg / cm³.2 This allows for the achievement of high capacity and excellent cycle performance, while the organic material can be recovered through a simple extraction method, thereby solving the technical problems of low organic electrode loading and lack of battery organic material recovery.

[0006] To achieve the above objectives, according to one aspect of the present invention, an azo-based organic zinc-ion battery is provided, wherein the positive electrode active material of the azo-based organic zinc-ion battery is azobenzene or functionally substituted azobenzene, and the loading of the positive electrode active material is 5–40 mg / cm³. 2 The negative electrode of the azo-based organic zinc-ion battery is a zinc-based material, and the solute in the aqueous electrolyte is a zinc salt.

[0007] Preferably, the functionalized azobenzene is at least one substituted azobenzene selected from halogen, nitro, methoxy, or methyl. These azo-based organic small molecule electrode materials utilize N=N double bonds as redox active sites to achieve reversible ion storage and release.

[0008] Preferably, the zinc-based material is zinc foil, zinc powder, zinc plate, porous zinc electrode, or zinc alloy.

[0009] Preferably, the zinc salt is at least one of zinc sulfate, zinc perchlorate, zinc acetate, zinc tetrafluoroborate, zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc trifluoromethanesulfonate, and bis(trifluoromethanesulfonylimide) zinc.

[0010] Preferably, the azo-type organic zinc-ion battery is a button cell or a pouch cell. Preferably, the pouch cell includes a single-layer pouch cell, a double-layer pouch cell, or a four-layer pouch cell.

[0011] According to another aspect of the present invention, a method for preparing an azo-based organic zinc-ion battery is provided, characterized in that a positive electrode active material, a conductive additive, and a binder are mixed into a slurry, which is then coated onto a current collector to obtain a positive electrode sheet, wherein the positive electrode active material is azobenzene or a functionally substituted azobenzene, and the loading of the positive electrode active material is 5–40 mg / cm³. 2 Zinc-based materials are used as the negative electrode, and an aqueous solution containing dissolved zinc salts is used as the electrolyte to assemble button cells or pouch cells.

[0012] When assembling pouch batteries, they are assembled in the manner of positive electrode, separator, and negative electrode. Multi-layer pouch batteries can be stacked and assembled, such as 2-layer and 4-layer pouch batteries.

[0013] Preferably, the mass ratio of the positive electrode active material, conductive additive and binder is (7-9):(2-0.5):(1-0.5).

[0014] Preferably, the conductive additive is at least one of acetylene black, carbon black, activated carbon, graphite, graphene, carbon fiber, carbon nanotubes, and mesoporous carbon; the binder is at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl alcohol, and sodium carboxymethyl cellulose; and the current collector is at least one of stainless steel mesh, graphite paper, carbon paper, carbon fiber cloth, and titanium mesh.

[0015] According to another aspect of the present invention, a method for recycling azo-based organic zinc-ion batteries is provided, characterized by comprising: placing a positive electrode sheet into a container containing an organic solvent, stirring or ultrasonically treating it and then filtering it; removing the solvent from the filtrate under vacuum conditions or allowing the solvent to evaporate to obtain recovered azobenzene or functionally substituted azobenzene; and obtaining conductive additives again by sequentially treating the filter cake with acid and at a temperature above 500°C.

[0016] Preferably, the organic solvent is at least one selected from methanol, ethanol, dichloromethane, chloroform, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, petroleum ether, n-hexane, or cyclohexane; the acid solution in the acid treatment is 0.1–1 mol / L dilute hydrochloric acid or dilute sulfuric acid.

[0017] Overall, the technical solutions conceived in this invention, compared with the prior art, can achieve at least the following beneficial effects.

[0018] (1) This invention uses azobenzene or functionally substituted azobenzene as a small-molecule organic cathode material. These azo-based small-molecule organic electrode materials use N=N double bonds as redox active sites, enabling reversible ion storage and release. The organic zinc-ion battery provided by this invention achieves high loading rates of 5–40 mg / cm³. 2 Even at low concentrations, it still exhibits high specific capacity and low polarization, for example, when the active material loading reaches 24 mg / cm³. 2 At around 1000 cycles, the battery's specific capacity can reach 150mAh / g.

[0019] (2) This invention strictly limits the types of functional groups in the functionalized azobenzene, which include one or more of halogen, nitro, methoxy, or methyl groups, in order to realize organic zinc-ion batteries with high loading capacities of 5–40 mg / cm³. 2 Even at this stage, it still exhibits high specific capacity and low polarization.

[0020] (3) At present, there is still a lack of research on the sustainability of redox active organic materials. This invention provides an economical and green recycling method that can recycle organic electrode materials in one step, which lays the foundation for the future development of sustainable batteries. Attached Figure Description

[0021] Figure 1AThis is a cycle performance diagram of the azobenzene organic electrode under different loadings in Example 1 of the present invention; Figure 1B This is a charge-discharge curve of the azobenzene organic electrode under different loadings in Example 1 of the present invention;

[0022] Figure 2 This is a graph showing the capacity and cycle performance of the single-layer azobenzene soft-pack battery in Embodiment 2 of the present invention;

[0023] Figure 3 This is a graph showing the capacity and cycle performance of the double-layer azobenzene soft-pack battery in Embodiment 2 of the present invention;

[0024] Figure 4 This is a charge-discharge curve of the 4-layer azobenzene soft-pack battery in Embodiment 2 of the present invention;

[0025] Figure 5 This refers to the recovery rate of the azobenzene electrode in three different organic solvents in Example 3 of this invention;

[0026] Figure 6A This is a cycle performance diagram of the 4-chloroazobenzene electrode in Example 4 of the present invention; Figure 6B This is a charge-discharge curve of the 4-chloroazobenzene electrode in Example 4 of the present invention;

[0027] Figure 7 This is a cycle performance diagram of 4-aminoazobenzene in Comparative Example 1 of the present invention;

[0028] Figure 8 This is a cyclic performance diagram of 4-hydroxyazobenzene in Comparative Example 2 of this invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Example 1

[0031] This embodiment provides an organic zinc-ion button cell. Specifically:

[0032] A slurry was prepared by mixing azobenzene as the organic active material, carbon black as the conductive additive, and PTFE as the binder in a mass ratio of 7:2:1. This slurry was then coated onto graphite paper to obtain the positive electrode sheet. The loading of the active material was 9.2 mg / cm³. 2 14.4 mg / cm 2 21.4 mg / cm 2 24.7 mg / cm2 36.8 mg / cm 2 A coin cell was assembled using zinc foil as the negative electrode and 2 mol / L zinc sulfate as the electrolyte. Figure 1A and Figure 1B As shown, the active material loading was 14.4 mg / cm³. 2 Even at this time, the battery still has a specific capacity of over 200 mAh / g and exhibits excellent cycle performance; even when the active material loading reaches 24.7 mg / cm³, the battery still maintains a specific capacity of over 200 mAh / g and exhibits excellent cycle performance. 2 At that time, the battery's specific capacity can reach 150mAh / g after 100 cycles. Furthermore, in... Figure 1B In the charge-discharge curves shown, the battery exhibits relatively small polarization under different load conditions.

[0033] Example 2

[0034] This embodiment provides an organic zinc-ion pouch battery. The assembly method of the pouch battery is as follows: Azobenzene is used as the organic active material, carbon black as the conductive additive, and PTFE as the binder. These are mixed in a mass ratio of 7:2:1 to prepare a slurry, which is then coated onto graphite paper with a size of 8×8cm to obtain the positive electrode sheet. The loading of the active material is 13 mg / cm³. 2 The electrode sheet is used as the organic positive electrode, and an 8×8cm zinc foil is used as the negative electrode. Each electrode sheet is connected to a tab, and the pouch cell is assembled in the order of positive electrode, separator, and negative electrode. By stacking them in the above manner, 2-layer and 4-layer pouch cells can be further assembled. Figure 2 As shown, a single-layer pouch cell exhibits a specific capacity of up to 160 mAh / g at a current density of 50 mA / g, resulting in a capacity of 0.13 Ah. Figure 3 As shown, the bilayer battery also exhibits excellent electrochemical performance. At a current density of 50 mA / g, the specific capacity remains as high as 160 mAh / g, with a capacity of 0.25 Ah. Furthermore, both single-layer and bilayer pouch cells demonstrate excellent cycling performance, with almost no capacity decay after 200 cycles. Figure 4 As shown, even in a 4-layer pouch battery system, the battery capacity can reach about 0.5Ah, making it an organic battery with great commercial application prospects.

[0035] Example 3

[0036] The active organic materials of the single-layer soft-pack battery in Example 2 were recovered. The electrode recovery method is as follows: The waste battery was disassembled, the positive electrode was removed, and the electrode was directly placed into a beaker containing acetonitrile, ethanol, or dichloromethane. After stirring or ultrasonic treatment for a certain period of time, the mixture was filtered. The filtrate was then desolvated under vacuum or allowed to evaporate naturally to obtain the recovered organic materials. The recovery rate is as follows: Figure 5As shown, the material recovery rate in three different low-boiling-point solvents is over 90%. Furthermore, the recovered filter cake can be washed sequentially with 0.1 mol / L sulfuric acid and water, and then carbonized at a high temperature above 500°C to obtain the conductive additive material again. This further demonstrates that the organic battery provided by this invention is a sustainable organic battery.

[0037] Example 4

[0038] A slurry was prepared by mixing 4-chloroazobenzene as the organic active material, carbon black as the conductive additive, and PTFE as the binder in a mass ratio of 7:2:1. This slurry was then coated onto graphite paper to obtain the positive electrode sheet. The active material loading was 11 mg / cm³. 2 A coin cell was assembled using zinc foil as the negative electrode and 2 mol / L zinc sulfate as the electrolyte. For example... Figure 6A and Figure 6B As shown, at a current density of 50 mA / g, the battery exhibits high capacity, a stable voltage plateau, and good cycle performance.

[0039] Example 5

[0040] The active organic materials of the coin cell in Example 4 were recovered. The electrode recovery method is as follows: the waste battery was disassembled, the positive electrode was removed, and the electrode was placed directly into a beaker containing dichloromethane. After stirring or ultrasonic treatment for a certain period of time, it was filtered, and the recovered organic materials were obtained after the solvent evaporated naturally. The recovery rate was calculated to be 90.1% after weighing.

[0041] Comparative Example 1

[0042] This comparative example provides a button cell battery, specifically:

[0043] A slurry was prepared by mixing 4-aminoazobenzene as the organic active material, carbon black as the conductive additive, and PTFE as the binder in a mass ratio of 7:2:1. This slurry was then coated onto graphite paper to obtain the positive electrode sheet. The active material loading was 11.4 mg / cm³. 2 A coin cell was assembled using zinc foil as the negative electrode and 2 mol / L zinc sulfate as the electrolyte.

[0044] from Figure 7 It can be seen that after 50 cycles, the specific capacity is 65 mAh / g, which is significantly smaller than the battery prepared in Example 1 using azobenzene or in Example 4 using 4-chloroazobenzene as the organic active material.

[0045] Comparative Example 2

[0046] This comparative example provides a button cell battery, specifically:

[0047] A slurry was prepared by mixing 4-hydroxyazobenzene as the organic active material, carbon black as the conductive additive, and PTFE as the binder in a mass ratio of 7:2:1. This slurry was then coated onto graphite paper to obtain the positive electrode sheet. The active material loading was 12.4 mg / cm³. 2 A coin cell was assembled using zinc foil as the negative electrode and 2 mol / L zinc sulfate as the electrolyte.

[0048] from Figure 8 It can be seen that after 100 cycles, the specific capacity decays rapidly, almost to 0, which is significantly less than the battery prepared using azobenzene as the organic active material in Example 1.

[0049] By comparing the results of the embodiments and comparative examples, it can be seen that azobenzene substituted with hydrophilic groups containing amino or hydroxyl groups is not suitable for the high-capacity requirements of this invention. The halogen, nitro, methoxy, or methyl groups specified in this invention are beneficial for achieving the desired performance of azobenzene. Those skilled in the art will readily understand that the above descriptions are merely preferred embodiments of this invention and are not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An azo-based organic zinc-ion battery, characterized by, The positive active material of the azo-based organic zinc ion battery is a functional group-substituted azobenzene, and the loading of the positive active material is 10-40 mg / cm 2 The negative electrode of the azo-based organic zinc ion battery is a zinc-based material, and the solute in the aqueous electrolyte is a zinc salt. The functional group-substituted azobenzene is at least one of halogen, nitro, methoxy or methyl-substituted azobenzene; The positive electrode sheet of the azo-based organic zinc ion battery is obtained by mixing the positive electrode active material, the conductive additive and the binder into a slurry and coating on a current collector, and the mass ratio between the positive electrode active material, the conductive additive and the binder is (7-9):(2-0.5):(1-0.5).

2. The azo-based organic zinc-ion battery of claim 1, wherein, The zinc-based material is zinc foil, zinc powder, zinc plate, porous zinc electrode or zinc alloy.

3. The azo-based organic zinc-ion battery of claim 1 or 2, wherein, The zinc salt is at least one of zinc sulfate, zinc perchlorate, zinc acetate, zinc tetrafluoroborate, zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc triflate, zinc bis(trifluoromethylsulfonylimide).

4. The azo-based organic zinc-ion battery of claim 1, wherein, The azo-based organic zinc ion battery is a button cell or a soft pack battery, and the soft pack battery includes a single-layer soft pack battery, a double-layer soft pack battery or a 4-layer soft pack battery.

5. A method of producing the azo-based organic zinc-ion battery as claimed in any one of claims 1 to 4, characterized by, Mixing a positive active material, a conductive additive and a binder into a slurry, coating the slurry onto a current collector to obtain a positive electrode sheet, wherein the positive active material is a functional group-substituted azobenzene, and the loading amount of the positive active material is 5-40 mg / cm 2 Assembling a button cell or a soft pack cell by using a zinc-based material as a negative electrode and an aqueous solution in which a zinc salt is dissolved as an electrolyte.

6. The production method according to claim 5, wherein The conductive additive is at least one of carbon black, activated carbon, graphite, graphene, carbon fiber, carbon nanotube and mesoporous carbon; the binder is at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl alcohol and sodium carboxymethyl cellulose; and the current collector is at least one of stainless steel mesh, graphite paper, carbon paper, carbon fiber cloth and titanium mesh.

7. A recovery method of the azo-based organic zinc-ion battery according to any one of claims 1 to 4, characterized by, The method comprises: The positive electrode sheet is placed in a container containing an organic solvent, stirred or ultrasonically treated, filtered, and the filtrate is obtained by removing the solvent under vacuum or after the solvent is volatilized; the filter cake is treated with acid and carbonized to obtain the conductive additive again; the organic solvent is at least one of methanol, ethanol, dichloromethane, chloroform, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, petroleum ether, n-hexane or cyclohexane.

8. The recycling method of claim 7, wherein, In the acid treatment, the acid solution is hydrochloric acid or sulfuric acid with a concentration of 0.1-1 mol / L; and the carbonization treatment temperature is above 500 DEG C.

Images