A zinc-air battery capable of biomass value-added and a preparation method thereof

Abstract

The present application relates to a kind of zinc-air battery that can realize biomass value-added and its preparation method, belong to metal-air battery and electrochemistry field;The present application uses organic molecule mediated biomass oxidation reaction to replace the oxygen evolution reaction in the charging process of traditional zinc-air battery, reduces battery charging voltage, improves energy conversion efficiency, while realizing biomass value-added, improves economic benefit, has important and broad application prospect in electrochemical energy storage and organic electrosynthesis field.

Description

Technical Field

[0001] This invention belongs to the field of metal-air battery and electrochemical technology, specifically relating to a zinc-air battery that enables biomass value-added and its preparation method. Background Technology

[0002] Metal-air batteries, with their high energy density, inherent safety, and potential low cost, are expected to become one of the candidates for next-generation electrochemical energy storage and conversion devices (EESCs), second only to lithium-ion batteries. Among them, aqueous zinc-air batteries (ZABs) are particularly promising due to their high theoretical energy density (1218 Wh / kg). -1 Zinc metal, with its low cost, high safety of aqueous electrolytes, and environmental friendliness, is considered a promising alternative to EESCs. Since its invention in the 19th century, alkaline primary ZABs have been commercialized in medical and telecommunications applications, but the development of rechargeable ZABs is still in its early stages, with several key issues remaining. One of the main problems is the high charging voltage of the battery, which is essentially due to the slow oxygen evolution reaction (OER) kinetics. During charging, this kinetics involves four proton coupling-electron transfer steps on the electrodes. Although the theoretical charging voltage of ZABs is 1.65 V, the actual charging voltage of ZABs is typically above 2 V, resulting in low energy efficiency. Furthermore, the side reactions caused by the high charging voltage can damage the electrode structure, significantly reducing the cycle stability of rechargeable ZABs. Therefore, improving OER kinetics is a core strategy for the further development of rechargeable ZABs.

[0003] To reduce the charging voltage of ZABs, extensive research has been conducted both domestically and internationally to construct highly active OER electrocatalysts (such as RuO2, Co3O4, and NiFe layered hydroxides) to improve OER kinetics. However, even using state-of-the-art noble metal-based electrocatalysts such as Pd, IrO2, and RuO2, the charge-discharge hysteresis voltage of conventional ZABs remains greater than 0.8 V (J. Mater. Chem. A, 2016, 4, 6282-6289. ACS Sustainable Chem. Eng. 2019, 7, 5462–5475. Applied Surface Science, 2022, 582, 152442). Recent studies have found that introducing semiconductor photoelectrodes into ZABs can improve OER kinetics and significantly reduce the charging voltage of ZABs. For example, under 365 nm ultraviolet light irradiation, using TiO2 as an air electrode, an ultra-low charging voltage of 0.59 V can be obtained, significantly lower than the theoretical voltage of ZABs (Angew. Chem. Int. Ed. 2020, 59, 18140-18144). However, problems such as photocorrosion of semiconductor photoelectrodes and the intermittency of light still limit the practical application of photosensitive rechargeable ZABs. In addition, the product of OER is oxygen, which has low economic value.

[0004] Therefore, in order to promote the development of ZABs and improve their energy conversion efficiency and economic benefits, high charging overvoltage is a technical problem that urgently needs to be solved; secondly, existing solutions have problems such as high cost and poor reliability.

[0005] Therefore, providing a zinc-air battery that can realize biomass value-added by replacing the OER in the traditional ZABs charging process with a more thermodynamically and kinetically favorable biomass oxidation reaction, and its preparation method, has become a problem worthy of research. Summary of the Invention

[0006] The purpose of this invention is to provide a zinc-air battery capable of realizing biomass value-added and its preparation method, and to develop a novel aqueous rechargeable ZABs. This ZAB has a low charging voltage, and biomass molecules can be simultaneously value-added during battery charging, improving energy efficiency and economic benefits. The ZABs prepared by this method use organic molecular catalysts and biomass molecules as electrolyte additives. During charging, the organic molecular catalyst in the electrolyte is directly oxidized on the electrode surface to form a cationic intermediate. This cationic intermediate catalyzes the oxidation of biomass molecules to generate value-added products, and is itself reduced to hydroxylamine. Under alkaline conditions, hydroxylamine undergoes a disproportionation reaction with the cationic intermediate to generate an organic molecular catalyst, thereby completing the electrochemical reaction cycle. During discharge, an oxygen reduction reaction (ORR) occurs at the cathode. Since the ORR (1.23 V vs. NHE) is thermodynamically more favorable than the reduction reaction of the organic molecular catalyst (-0.38 V vs. NHE), the ORR reaction preferentially occurs at the cathode, which is key to the high discharge voltage maintained by this novel ZAB. This also means that by using organic molecular catalysts and biomass molecules as electrolyte additives, low charging voltage, biomass amplification, and high discharge voltage can be simultaneously achieved in rechargeable water ZABs. The charging voltage of this novel ZAB can be reduced to 1.6 V, exhibiting charge-discharge cycle stability exceeding 400 hours. The ZABs prepared by this method provide an effective strategy for reducing the charging voltage of metal-air batteries. More importantly, the preparation process of this novel ZAB is simple, low-cost, and can be mass-produced, representing a highly efficient and green pathway for biomass conversion and even organic electrosynthesis reactions.

[0007] A zinc-air battery capable of biomass value-added includes a metallic zinc negative electrode, a hydrophobic carbon paper air cathode, and an aqueous electrolyte containing organic molecular catalysts and biomass molecules. During charging, the organic molecular catalyst in the aqueous electrolyte is directly oxidized on the electrode surface to form a cationic intermediate. The cationic intermediate catalyzes the oxidation of biomass molecules to generate value-added products, and the cationic intermediate itself is reduced to hydroxylamine. Under alkaline conditions, hydroxylamine and the cationic intermediate undergo a disproportionation reaction to generate an organic molecular catalyst, thereby completing the electrochemical reaction cycle. During discharge, an oxygen reduction reaction occurs at the cathode. Since the oxygen reduction reaction is thermodynamically more favorable than the reduction reaction of the organic molecular catalyst, the ORR reaction preferentially occurs at the cathode. By using organic molecular catalysts and biomass molecules as electrolyte additives, low charging voltage, biomass value-added, and high discharge voltage can be simultaneously achieved in rechargeable water-based ZABs.

[0008] The organic molecular catalyst is any one of TEMPO and TEMPO derivatives.

[0009] The biomass molecule is any one of glucose, methanol, ethanol, benzyl alcohol, 5-hydroxymethylfurfural, and glycerol.

[0010] The aqueous electrolyte is either KOH or NaOH aqueous solution.

[0011] A method for preparing a zinc-air battery capable of biomass value-added includes the following steps:

[0012] Step 1. Electrode and Aqueous Electrolyte Preparation: Grind the zinc sheet / plate to remove the surface oxide layer, using it as the negative electrode; use hydrophobic carbon paper as the positive electrode; prepare an aqueous electrolyte solution containing TEMPO and glucose (KOH or NaOH) for use as the aqueous electrolyte. Step 2. Battery Assembly: Fix the positive and negative electrodes from Step 1 to both sides of the battery. The positive electrode is fixed using an air electrode to form a solid-liquid-gas three-phase reaction interface; use a peristaltic pump to circulate the electrolyte, accelerating the mass transfer process of biomass molecules and ensuring complete reaction of biomass molecules.

[0013] The aqueous electrolyte preparation method in step 1 includes the following steps:

[0014] Step a1. Dissolve solid KOH or solid NaOH in deionized water to prepare an aqueous solution of KOH or NaOH.

[0015] Step a2. Dissolve solid TEMPO in the KOH or NaOH aqueous solution described in step a1 to obtain a KOH aqueous solution or a NaOH aqueous solution containing TEMPO;

[0016] Step a3. Dissolve glucose in the KOH aqueous solution containing TEMPO or the NaOH aqueous solution containing TEMPO from step a2 to obtain an aqueous solution containing glucose and TEMPO or an aqueous solution containing glucose and TEMPO, which is the aqueous electrolyte in step 1.

[0017] The aqueous electrolyte contains both glucose and TEMPO.

[0018] The concentration of the KOH or NaOH aqueous solution in step a1. is 1~6 mol L. -1 ;

[0019] In step a2, the concentration of TEMPO in the KOH aqueous solution or NaOH aqueous solution containing TEMPO is 1-20 mmol / L. -1 It is prepared using acetonitrile;

[0020] The concentration of glucose in the KOH aqueous solution containing glucose and TEMPO or the NaOH aqueous solution containing glucose and TEMPO in step a3. is 10~200 mmol / L. -1 .

[0021] The glucose in step 1 is converted by constant current charge-discharge method or constant voltage electrolysis method. The specific operation steps are as follows: the assembled zinc-air battery in step 2 is subjected to constant current charge-discharge or constant voltage electrolysis to convert glucose into glucose derivatives. The conversion of glucose can both regenerate organic molecular catalysts and produce high-value-added glucose derivatives. This process can reduce the charging voltage of zinc-air battery and realize the value-added of glucose.

[0022] The current density of the constant current charge / discharge is 0.1~10 mA cm⁻¹. -2 The voltage of the constant voltage electrolysis is 1.5~2.0 V, and the time of the constant current charge-discharge and constant voltage electrolysis is 10~100 hours.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. This invention reduces the charging voltage of zinc-air batteries by adding organic molecular catalysts and biomass molecules to the electrolyte, while simultaneously realizing the value-added of biomass molecules during the charging process, thereby improving energy efficiency and economic benefits.

[0025] 2. The preparation process of this invention is simple, low-cost, and environmentally friendly;

[0026] 3. The novel zinc-air battery of this invention has great application prospects in fields such as large-scale static energy storage and high-value-added chemical production. Attached Figure Description

[0027] Figure 1 This is a comparison of the electrochemical performance of the TEMPO-mediated catalytic glucose oxidation reaction in Example 1 of the present invention with that of the conventional OER reaction;

[0028] Figure 2 The cyclic voltammetry curves for the TEMPO-mediated oxidation of methanol (a), ethanol (b), benzyl alcohol (c), and 5-hydroxymethylfurfural (c) in Example 1 of this invention are shown.

[0029] Figure 3 The LSV curves of the platinum electrode in N2-saturated 1 M KOH with and without TEMPO are shown in Example 1 of this invention, with a scan rate of 10 mV / s. -1 ;

[0030] Figure 4 This is a scanning electron microscope image of N-RGO in Embodiment 2 of the present invention;

[0031] Figure 5 The X-ray photoelectron spectroscopy (XPS) broad scan and N 1s fine XPS spectrum of N-RGO in Example 2 of this invention are shown.

[0032] Figure 6 The contact angles of N-RGO before and after modification of hydrophobic carbon paper (CC) in Example 2 of this invention are shown.

[0033] Figure 7 The electrochemical performance of N-RGO / CC and CC in Example 2 of this invention; (a) Linear sweep voltammetry curves, scan rate 5 mV s. -1 (b) AC impedance curve, with a bias voltage of -0.3 V applied;

[0034] Figure 8 (a) Schematic diagram and working mechanism of the zinc-air battery in Example 3 of the present invention; (b) Charging curves of the zinc-air battery in Example 3 of the present invention and a conventional zinc-air battery; (c) Charge-discharge curves of the zinc-air battery in Example 3 of the present invention; (d) Cyclic performance of the zinc-air battery in Example 3 of the present invention and a conventional zinc-air battery; (e) Cyclic performance of the zinc-air battery in Example 3 of the present invention;

[0035] Figure 9 This is a digital photograph showing the open-circuit voltage of the zinc-air battery and the LED light being lit in Embodiment 3 of the present invention.

[0036] Figure 10 This is a SEM image of the zinc negative electrode after cycling in the zinc-air battery of Embodiment 3 of the present invention;

[0037] Figure 11 The XRD pattern of the zinc negative electrode after cycling in the zinc-air battery of Example 3 of this invention;

[0038] Figure 12 This is a SEM image of the zinc negative electrode after cycling in a conventional zinc-air battery according to Example 3 of the present invention.

[0039] Figure 13 This is the XRD pattern of the zinc negative electrode after cycling in a conventional zinc-air battery, as shown in Example 3 of this invention.

[0040] Figure 14 Infrared and hydrogen nuclear magnetic resonance spectra of glucose, gluconic acid, glucuronic acid standards and electrolytes of the zinc-air battery in Example 3 of this invention after different cycles.

[0041] Figure 15 Example 4 of the present invention describes the cycle performance of zinc-air batteries using KOH solution (a) containing glucose and KOH solution (b) containing TEMPO, respectively.

[0042] Figure 16In Example 5 of this invention, 1 mol L -1 The LSV curve of the glucose oxidation reaction mediated by TEMPO was obtained using NaOH aqueous solution as the electrolyte. Detailed Implementation

[0043] The present invention will be described in more detail through specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0044] Example 1

[0045] Prepare 1.0 mol L by dissolving solid KOH. -1 KOH aqueous solution. A glassy carbon electrode (3 mm in diameter) was used as the working electrode, Ag / AgCl (saturated KCl) as the reference electrode, and a Pt foil (1 cm²) was used. 2 Using a typical three-electrode cell as the counter electrode, cyclic voltammetry and linear voltammetry were performed without stirring. The potential window was 0–0.8 V, and the scan rate was 10 mV / s. -1 A mixture containing Pt / C and RuO2 in a 1:1 mass ratio was dispersed in N,N-dimethylformamide (DMF). Five mL of the dispersion containing 0.5% Nafion was dropped onto the surface of a glassy carbon electrode and dried at room temperature to obtain a Pt / C-RuO2 modified electrode. Electrochemical tests of the Pt / C-RuO2 modified electrode were performed at 1.0 mol / L... -1 The process is carried out in KOH aqueous solution.

[0046] This embodiment compares the electrochemical performance of TEMPO-mediated glucose oxidation with that of conventional OER reactions, such as... Figure 1 As shown, the TEMPO-mediated glucose oxidation reaction exhibits more favorable reaction thermodynamics and kinetics than the conventional OER reaction catalyzed by noble metal catalysts. Furthermore, from... Figure 1 b shows that TEMPO has a mediating catalytic oxidation effect on glucose derivatives (gluconic acid, glucuronic acid), indicating that TEMPO has the ability to deeply oxidize glucose.

[0047] This embodiment involves applying 1.0 mol L... -1 TEMPO and common biomass molecules (methanol, ethanol, benzyl alcohol, 5-hydroxymethylfurfural) were added to KOH aqueous solution to study the electrochemical behavior between TEMPO and these biomass molecules. For example... Figure 2 As shown, the addition of biomass molecules such as methanol, ethanol, benzyl alcohol, and 5-hydroxymethylfurfural significantly increases the oxidation current, indicating that TEMPO has the ability to mediate the catalytic oxidation of these biomass molecules. Furthermore, the addition of TEMPO molecules effectively suppresses the hydrogen evolution side reaction, such as... Figure 3 As shown.

[0048] Example 2

[0049] 1 g of flake graphite was weighed and mixed with 30 mL of concentrated sulfuric acid. 3 g of KMnO4 was slowly added under an ice-water bath. After stirring for 2 h, the temperature was raised to 35 °C and stirred for 30 min. Then, 50 mL of deionized water was slowly added, and the temperature was raised to 90 °C and held for 30 min. The mixture was diluted to 100 mL of deionized water, and 5 mL of 30% H2O2 was added. After centrifugation, the mixture was washed with 10% hydrochloric acid and deionized water, respectively, and then freeze-dried to obtain graphene oxide. 0.5 g of graphene oxide was ultrasonically dispersed in 50 mL of hydrazine hydrate (50%). The resulting mixture was sealed in a hydrothermal reactor (100 mL) and kept at 180 °C for 12 h. After cooling, the product was thoroughly washed with deionized water and freeze-dried to obtain N-RGO. The morphology of the sample was characterized using field emission scanning electron microscopy (SEM) at an accelerating voltage of 10 kV. The surface composition of N-RGO was analyzed using XPS.

[0050] N-RGO was ultrasonically dispersed in DMF to prepare a dispersion (10 mg / mL). -1 Five mL of N-RGO dispersion containing 0.5% Nafion was dropped onto the CC surface and dried at room temperature. Pt / C-RuO2-modified CC air cathodes were prepared using a method similar to that used for N-RGO / CC preparation. The loading of N-RGO or Pt / C-RuO2 on the CC was 1.0 mg cm⁻¹. -2 In a three-electrode system, the electrochemical performance of N-RGO or Pt / C-RuO2 modified CC electrodes was tested using cyclic voltammetry and electrochemical impedance spectroscopy.

[0051] like Figure 4 As shown, the obtained N-RGO exhibits a typical lamellar wrinkled structure. XPS analysis results indicate that the N atom content of N-RGO is 4.74 at.%, primarily existing in pyridine, pyrrole, and graphitized N configurations, such as... Figure 5 As shown. The introduction of nitrogen heteroatoms can increase the wettability of the electrolyte and improve the electrocatalytic oxygen reduction performance of the material. For example... Figure 6 As shown, the water contact angle of N-RGO / CC is 146.5° compared to the original CC. o It became 119.9 o This indicates that the hydrophobicity of CC is reduced after N-RGO modification.

[0052] This embodiment improves the electrocatalytic oxygen reduction performance of the electrode through N-RGO modification. The electrocatalytic oxygen reduction performance of N-RGO / CC and the original CC is as follows: Figure 7As shown in Figure a, the onset potential of N-RGO / CC for electrocatalytic oxygen reduction is -0.15 V (vs. Ag / AgCl), which is superior to that of the original CC (-0.35 V vs. Ag / AgCl). Furthermore, at a bias voltage of -0.5 V (vs. Ag / AgCl), the oxygen reduction current of N-RGO / CC is significantly higher than that of the original CC. At a bias voltage of -0.3 V (vs. Ag / AgCl), the charge transfer impedance of N-RGO / CC is significantly lower than that of the original CC. Figure 7 As shown in b. The above results indicate that N-RGO modification significantly enhances the electrocatalytic oxygen reduction performance of the electrode, which is beneficial for increasing the discharge voltage of the battery.

[0053] Example 3

[0054] Using polished zinc sheet as the negative electrode and CC or N-RGO / CC as the air cathode, 1.0 mol L -1 KOH contains 10 mmol L -1 TEMPO and 100 mmol L -1 Aqueous glucose solution was used as the electrolyte to assemble a zinc-air battery. Polished zinc sheet was used as the negative electrode, and Pt / C-RuO2 / CC was used as the air cathode. 1.0 mol L⁻¹ -1 A conventional zinc-air battery was assembled using KOH aqueous solution as the electrolyte. The cycle stability of the zinc-air battery was investigated using constant current charge-discharge. X-ray diffraction (XRD) was used to investigate the phase structure of the zinc metal anode surface after cycling. SEM was used to characterize the morphology of the zinc metal anode before and after cycling at an accelerating voltage of 10 kV. Infrared spectroscopy and proton nuclear magnetic resonance (NMR) spectroscopy of the electrolyte after cycling were performed to investigate the conversion of biomass molecules.

[0055] This embodiment compares and studies the performance of zinc-air batteries using different electrolytes. Figure 8 a is a schematic diagram of the zinc-air battery structure and working mechanism of the present invention. Figure 8 Figure b shows the charging curves of the zinc-air battery of this invention and a conventional zinc-air battery. As can be seen from the figure, the zinc-air battery of this invention has the lowest charging voltage (1.62 V), significantly lower than that of conventional zinc-air batteries based on noble metal catalysts. The charge / discharge voltage hysteresis of the zinc-air battery of this invention is only 0.54 V. Figure 8 As shown in c. After 3000 minutes of charge-discharge cycles, the charging voltage of the zinc-air battery of this invention remained at 1.63 V, as... Figure 8 As shown in d. Using N-RGO / CC as the air cathode further improves the discharge voltage of the zinc-air battery of this invention. For example... Figure 8 As shown in Figure e, after a long-term cycling period of 400 hours, the charging voltage of the zinc-air battery of the present invention remains at 1.65 V. The voltage of a single cell in the zinc-air battery of the present invention can reach 1.5 V, as shown in Figure e. Figure 9 As shown in figure a. Two zinc-air batteries of this invention connected in series can achieve an open-circuit voltage of 2.86 V, as shown in figure a. Figure 9 As shown in b. Two zinc-air batteries of this invention connected in series can light one or two LEDs connected in parallel, such as... Figure 9 As shown in c and d, the microstructure of the metallic zinc negative electrode before and after cycling in the zinc-air battery of the present invention is as follows. Figure 10 As shown. Before cycling, the zinc anode surface was smooth and flat; after cycling, particles adhered to the zinc anode. XRD test results showed that the surface composition of the zinc anode was Zn(OH)2, as... Figure 11 As shown. After cycling, the zinc negative electrode surface of a traditional zinc-air battery develops a spiky, spherical morphology, such as... Figure 12 As shown. XRD test results indicate that the spiky, spherical material on the zinc anode surface is ZnO, as... Figure 13 As shown. Figure 14 a and b are the proton NMR spectrum and infrared spectrum of the electrolyte of the zinc-air battery of the present invention under different cycles. Figure 14 c and d are the 1H NMR and IR spectra of standard samples glucose, gluconic acid, and glucuronic acid, respectively. The comparison shows that in the zinc-air battery of this invention, glucose is oxidized during the charging and discharging process to generate high-value-added chemicals such as gluconic acid and glucuronic acid.

[0056] Example 4

[0057] Using polished zinc sheet as the negative electrode and N-RGO / CC as the air cathode, 1.0 mol L... -1 KOH contains 100 mmol / L -1 An aqueous solution of glucose and 1.0 mol L -1 KOH contains 10 mmol / L -1 An aqueous solution of TEMPO was used as the electrolyte to assemble a zinc-air battery. The cycle stability of the zinc-air battery was investigated using constant current charge-discharge.

[0058] This embodiment compares and studies the performance of zinc-air batteries using different electrolytes. For example... Figure 15 As shown in Figure a, the initial charging voltage of the zinc-air battery using glucose aqueous solution as the electrolyte is as high as 2.01 V. After 100 h of charge-discharge, the charging voltage is still as high as 1.96 V, indicating that under these conditions, the glucose oxidation reaction is still a kinetically slow anodic reaction. Figure 15As shown in b, the initial charging voltage of the zinc-air battery using an aqueous TEMPO solution as the electrolyte exceeded 1.8 V. After 20 h, the charging voltage decreased to 1.62 V, and after 100 h, it gradually increased to 1.77 V. The increase in charging voltage can be attributed to the consumption of TEMPO, as TEMPO cannot be regenerated without glucose. This result highlights the importance of the coexistence of glucose and TEMPO in the electrolyte.

[0059] Example 5

[0060] Prepare 1.0 mol L by dissolving solid NaOH. -1 A typical three-electrode cell was used with NaOH aqueous solution, a glassy carbon electrode (3 mm in diameter) as the working electrode, Ag / AgCl (saturated KCl) as the reference electrode, and a Pt foil (1 cm²) as the counter electrode. Linear voltammetry was performed without stirring, with a potential window of 0–0.8 V and a scan rate of 10 mV / s. -1 .

[0061] This embodiment aims to study the characteristics of glucose oxidation mediated by TEMPO in NaOH aqueous solution. For example... Figure 16 As shown, add 100 mmol L -1 After glucose was added, the anolyte current increased sharply, indicating that the glucose oxidation reaction mediated by TEMPO in NaOH aqueous solution is similar to that in KOH aqueous solution. Therefore, NaOH aqueous solution can be used as the supporting electrolyte for the zinc-air battery of this invention.

[0062] The above are merely preferred embodiments of the present invention and should not be construed as limiting the technical scope of the present invention. Therefore, any simple equivalent changes and modifications made with reference to the contents of the present invention's specification should still fall within the protection scope of the present invention.

Claims

1. A zinc-air battery capable of realizing biomass value-added processing, characterized in that: The device includes a zinc metal anode, a hydrophobic carbon paper air cathode, and an aqueous electrolyte containing organic molecular catalysts and biomass molecules. During charging, the organic molecular catalysts in the aqueous electrolyte are directly oxidized on the electrode surface to form cationic intermediates. The cationic intermediates catalyze the oxidation of biomass molecules to generate value-added products, and the cationic intermediates themselves are reduced to hydroxylamine. Under alkaline conditions, hydroxylamine undergoes a disproportionation reaction with a cationic intermediate to generate an organic molecular catalyst, thereby completing the electrochemical reaction cycle. During discharge, an oxygen reduction reaction occurs at the cathode. Since the oxygen reduction reaction is thermodynamically more favorable than the reduction reaction of the organic molecular catalyst, the ORR reaction preferentially occurs at the cathode. By using organic molecular catalysts and biomass molecules as electrolyte additives, low charging voltage, biomass amplification, and high discharge voltage can be simultaneously achieved in a rechargeable aqueous zinc-air battery. The organic molecular catalyst is any one of TEMPO and TEMPO derivatives; the biomass molecules are any one of glucose, methanol, ethanol, benzyl alcohol, 5-hydroxymethylfurfural, and glycerol.

2. The zinc-air battery capable of realizing biomass value-added as described in claim 1, characterized in that: The aqueous electrolyte is either KOH or NaOH aqueous solution.

3. A method for preparing a zinc-air battery capable of biomass value-added as described in any one of claims 1-2, characterized in that: Includes the following steps: Step 1. Electrode and Aqueous Electrolyte Preparation: Grind the zinc sheet / plate to remove the surface oxide layer, using it as the negative electrode; use hydrophobic carbon paper as the positive electrode; prepare an aqueous electrolyte solution containing TEMPO and glucose (KOH or NaOH) for use as the aqueous electrolyte. Step 2. Battery Assembly: Fix the positive and negative electrodes from Step 1 to both sides of the battery. The positive electrode is fixed using an air electrode to form a solid-liquid-gas three-phase reaction interface; use a peristaltic pump to circulate the electrolyte, accelerating the mass transfer process of biomass molecules and ensuring complete reaction of biomass molecules.

4. The method for preparing a zinc-air battery capable of biomass value-added according to claim 3, characterized in that: The aqueous electrolyte preparation method in step 1 includes the following steps: Step a1. Dissolve solid KOH or solid NaOH in deionized water to prepare an aqueous solution of KOH or NaOH. Step a2. Dissolve solid TEMPO in the KOH or NaOH aqueous solution described in step a1 to obtain a KOH aqueous solution or a NaOH aqueous solution containing TEMPO; Step a3. Dissolve glucose in the KOH aqueous solution containing TEMPO or the NaOH aqueous solution containing TEMPO from step a2 to obtain an aqueous solution containing glucose and TEMPO, which is the aqueous electrolyte in step 1.

5. The method for preparing a zinc-air battery capable of biomass value-added according to claim 4, characterized in that: The aqueous electrolyte contains both glucose and TEMPO. The concentration of the KOH aqueous solution or NaOH aqueous solution in step a1. is 1~6 mol L. -1 ; In step a2, the concentration of TEMPO in the KOH aqueous solution or NaOH aqueous solution containing TEMPO is 1-20 mmol / L. -1 ; The concentration of glucose in the KOH aqueous solution containing glucose and TEMPO or the NaOH aqueous solution containing glucose and TEMPO in step a3. is 10~200 mmol / L. -1 .

6. The method for preparing a zinc-air battery capable of biomass value-added according to claim 3, characterized in that: The glucose in step 1 is converted by constant current charge-discharge method or constant voltage electrolysis method. The specific operation steps are as follows: the assembled zinc-air battery in step 2 is subjected to constant current charge-discharge or constant voltage electrolysis to convert glucose into glucose derivatives. The conversion of glucose can both regenerate organic molecular catalysts and produce high-value-added glucose derivatives. This process can reduce the charging voltage of zinc-air battery and realize the value-added of glucose. The current density of the constant current charge / discharge is 0.1~10 mA cm⁻¹. -2 The voltage of the constant voltage electrolysis is 1.5~2.0V, and the time of the constant current charge-discharge and constant voltage electrolysis is 10~100 hours.

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