Zinc-based flow battery negative electrode material and preparation method and application thereof

Abstract

The application discloses a zinc-based flow battery negative electrode material and a preparation method and application thereof, and belongs to the technical field of electrochemical energy storage. The zinc-based flow battery negative electrode material is a porous conductive substrate with in-situ grown zincophilic metal nanometer arrays; the zincophilic metal is selected from one or more of bismuth, indium, tin, antimony, silver, copper, gold, lead, cadmium, germanium and zinc; the thickness of nanometer sheets of the nanometer arrays is 2-10 nm, the height of the nanometer sheets is 150-200 nm, and the gap between the nanometer sheets is 20-500 nm. The application first proposes a zinc-based flow battery negative electrode interface modification system based on zincophilic metal induction and nanometer confinement coordination. Compared with a traditional single zincophilic coating or a conventional porous electrode system, the system constructed by the application fundamentally eliminates the failure caused by the peeling of an active layer under the double stresses of fluid scouring and volume expansion, and has the innate advantages of strong interface bonding force, low induced nucleation energy barrier and strong physical confinement capability.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, specifically relating to a zinc-based flow battery anode material, its preparation method, and its application. Background Technology

[0002] With the increasing proportion of renewable energy globally, developing large-scale energy storage systems that are low-cost, highly safe, and long-lasting has become an urgent priority. Zinc-bromine flow batteries (ZBFBs) possess high theoretical energy density (approximately 440 Wh·kg⁻¹). -1 Zinc-bromine flow batteries, with their significant advantages such as low electrolyte cost and abundant zinc and bromine resources, are considered one of the most promising long-term energy storage technologies. However, the commercialization of zinc-bromine flow batteries is severely hampered by the irreversibility of zinc metal in the negative electrode under high load and flow conditions. To meet the high areal capacity (≥20 mAh·cm³) required for practical applications... -2 In this process, the negative electrode faces the challenge of deep deposition. Tiny, inhomogeneous nucleation and disordered mass transfer behavior can easily be amplified into coarse dendrites. This not only increases the risk of short circuits caused by puncturing the separator, but the loose dendrites are also prone to detaching under the continuous shear force of the circulating electrolyte, forming "dead zinc," which accumulates and blocks the flow channels. This irreversible morphological degradation accumulates continuously during long-term operation, severely limiting the cumulative plating capacity (CPC) of the battery, i.e., the total zinc deposition capacity that the battery can withstand before failure. Existing technologies often experience early failure at relatively low CPC, making it difficult to meet the stringent requirements of long system life and high reliability for large-scale energy storage.

[0003] Although the construction of zinc-affinity sites and defect engineering has been studied for many years in zinc anode modification, no research or technical solution has yet successfully proposed or constructed an ultra-stable composite anode system that integrates zinc-affinity metal induction and nanoscale spatial confinement, and can adapt to the high shear conditions of flow batteries. It is well known that the nucleation thermodynamics and mass transfer kinetics of zinc ions are two key factors determining the density and stability of the deposited layer. However, achieving such a system faces bottlenecks that are difficult to overcome with existing single strategies. Traditional zinc-affinity sites are mostly attached to the substrate surface in the form of metal or oxide particles and coatings. Although they can induce zinc deposition in the early stages, as the charging surface capacity gradually increases, these initial nucleation sites located at the bottom layer are rapidly covered, causing the subsequent thick zinc deposition process to lose its inductive control, easily leading to cumulative uneven growth and dendrite formation. On the other hand, while defect engineering can improve mass transfer and electric field distribution during the initial growth process by introducing vacancies or heteroatoms, it inherently lacks effective strong zinc-affinity initial nucleation sites. Unlike zinc-affinity metals, it cannot significantly reduce the nucleation overpotential, resulting in difficulty in precisely controlling the initial adsorption and nucleation behavior of zinc ions under high flow rates and high current densities. Therefore, developing a novel anode technology based on zinc-affinity metal nanoconfinement engineering is a gap in this field and has significant scientific value and application prospects. Summary of the Invention

[0004] The purpose of this invention is to provide a zinc-based flow battery anode material, its preparation method, and its applications. It aims to solve the technical challenges of existing zinc-based flow battery anodes under the dual harsh conditions of "high cumulative deposition capacity" and "strong fluid shear," such as uncontrolled zinc dendrite growth, active layer peeling and detachment, and "dead zinc" clogging of flow channels due to the failure of induced sites and lack of physical constraints. By constructing an in-situ grown, morphology-customized zinc-loving metal array, thermodynamically low-energy-barrier induced nucleation and kinetically uniform mass transfer confinement are achieved, thereby significantly improving the battery's cumulative deposition capacity, erosion resistance, and cycle life.

[0005] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a zinc-based flow battery anode material, which is a porous conductive substrate for in-situ growth of zinc-loving metal nanoarrays; The zinc-loving metal is selected from one or more of bismuth (Bi), indium (In), tin (Sn), antimony (Sb), silver (Ag), copper (Cu), gold (Au), lead (Pb), cadmium (Cd), germanium (Ge) and zinc (Zn); The nanosheets of the nanoarray have a thickness of 2–10 nm, a height of 150–200 nm, and a gap of 20–500 nm between them.

[0006] The porous conductive substrate for in-situ growth of zinc-loving metal nanoarrays provided by this invention has the following advantages: 1. In-situ anchoring mechanism constructs an ultra-stable shear-resistant interface: This invention employs an in-situ growth strategy to form a strong atomic / chemical bond between the zinc-loving metal array and the substrate. This binder-free endogenous structure has extremely high shear modulus, effectively resisting the high-speed scouring of the electrolyte and the volume expansion stress generated by zinc deposition. This fundamentally eliminates active layer peeling and the formation of "dead zinc," significantly improving the battery's operational reliability under flowing conditions.

[0007] 2. Low-barrier-induced thermodynamically stable dense deposition: A customized zinc-loving metal array significantly reduces the nucleation overpotential of zinc ions, eliminating the nucleation hindrance effect on the heterogeneous substrate. Utilizing its excellent lattice-matching properties, the array induces dense filling of zinc metal in an epitaxial growth mode, suppressing tip effects and dendrite germination from a thermodynamic perspective, ensuring morphological stability under high areal capacity conditions.

[0008] 3. Nanochannel modulation achieves kinetically uniform mass transfer distribution: Based on morphology engineering, a nanoscale array of gaps forms regular ion mass transfer channels, effectively redistributing the electric and ion flow fields on the electrode surface. This structure significantly alleviates concentration polarization under high current density, achieving uniform Zn... 2+ Flux homogenization enables the battery to maintain a flat and dense deposition layer even with extremely high cumulative deposition capacity, significantly improving the system's rate performance and energy efficiency.

[0009] Preferably, the porous conductive substrate is selected from graphite felt, carbon felt, carbon cloth or carbon paper.

[0010] The porous conductive substrate used in this invention has a three-dimensional interconnected pore structure to provide macroscopic electrolyte channels and electron transport framework.

[0011] Preferably, the zinc-loving metal is bismuth.

[0012] The second technical solution of the present invention provides a method for preparing the above-mentioned zinc-based flow battery negative electrode material, comprising the following steps: First, the porous conductive substrate is hydrophilized. Then, an in-situ growth strategy is used to induce the direct nucleation of zinc-loving metal precursors on the surface of the porous conductive substrate. After the zinc-loving metal precursors are reduced, zinc-loving metal nanoarrays are formed.

[0013] Preferably, the hydrophilic treatment method includes, but is not limited to: heat treatment of the porous conductive substrate at a high temperature of 300-600°C and an oxygen content of not less than 20 vol% (such as air or other oxygen-rich atmosphere); or chemical oxidation treatment of the porous conductive substrate in an acidic solution; or plasma etching treatment of the porous conductive substrate.

[0014] The present invention provides a hydrophilic treatment to porous conductive substrates, which can enhance the bonding force between the substrate and the nanoarray. The above hydrophilic treatment can introduce oxygen-containing functional groups on the surface of porous conductive substrates to improve electrolyte wettability.

[0015] Preferably, the in-situ growth strategy includes, but is not limited to: hydrothermal method, solvothermal method, electrochemical deposition method or chemical bath deposition method.

[0016] More preferably, when the zincophile metal is bismuth and the in-situ growth strategy is hydrothermal, the preparation step of the zincophile metal precursor includes: placing the porous conductive substrate on a Bi... 3+ A zinc-loving metal precursor was obtained by hydrothermal reaction at 160–240 °C for 16–24 h in a precursor solution with a concentration of 40–120 mmol / L and an ammonium chloride concentration of 100–300 mmol / L.

[0017] This invention controls the growth of precursors into nanoarray structures with specific geometric features by introducing crystal plane guiding agents and adjusting reaction kinetics during precursor growth.

[0018] Preferably, the reduction method includes, but is not limited to, electrochemical reduction or thermal reduction. After reduction, annealing may be performed as needed to strengthen the interfacial bonding between the zinc-loving metal nanoarray and the substrate.

[0019] The third technical solution of the present invention provides an aqueous zinc-bromine flow battery, the components of which include: a positive electrode, a negative electrode, a separator, an electrolyte, a storage tank, and a drive pump; the material of the negative electrode is the aforementioned zinc-based flow battery negative electrode material; the electrolyte is an aqueous solution containing zinc ions and bromide ions.

[0020] Preferably, the concentration of zinc ions in the electrolyte is 1-3 mol / L and the concentration of bromide ions is 2-6 mol / L.

[0021] More preferably, the electrolyte further comprises a supporting electrolyte for improving the ionic conductivity of the solution and a bromine complexing agent (BCA) for reducing the volatility of bromine and self-discharge. During charging, the bromine complexing agent combines with the elemental bromine generated at the positive electrode to form a water-insoluble oil-phase complex. The bromine complexing agent is a quaternary ammonium salt compound, including but not limited to one or more combinations of N-methyl-N-ethylpyrrolidine ammonium bromide (MEP), N-methyl-N-ethylmorpholine ammonium bromide (MEM), 1-ethyl-3-methylimidazolium bromide (EMImBr), tetrabutylammonium bromide (TBAB), and dodecyltrimethylammonium bromide (DTAB).

[0022] More preferably, the electrolyte further comprises a supporting electrolyte, which includes, but is not limited to, one or more combinations of potassium chloride (KCl), sodium chloride (NaCl), lithium chloride (LiCl), and ammonium chloride (NH4Cl).

[0023] The positive and negative electrode reaction principles of the aqueous zinc-bromine flow battery are as follows: Negative electrode reaction: Zn 2+ +2e - →Zn; Positive electrode reaction: 2Br - -2e - →Br2.

[0024] The structural schematic diagram of the aqueous zinc-bromine flow battery provided by this invention is shown below. Figure 1 As shown, 1 is the negative electrode, 2 is the positive electrode, 3 is the negative electrolyte storage tank, 4 is the positive electrolyte storage tank, 5 is the diaphragm, 6 is the negative peristaltic pump, and 7 is the positive peristaltic pump.

[0025] The negative electrode 1 adopts the zinc-based flow battery negative electrode material based on the synergistic effect of zinc-loving metal-induced and nano-confined systems provided in this invention. This electrode structure can withstand the shear erosion of high-flow-rate electrolytes and ensures high areal capacity (≥20 mAh·cm³). -2 Structural stability under deposition.

[0026] Positive electrode 2: It adopts a porous carbon material with high specific surface area and good catalytic activity, including but not limited to graphite felt, carbon felt, activated carbon cloth or carbon paper.

[0027] Battery separator 5: Select a porous membrane or ion exchange membrane with ion selective permeability, including but not limited to polyolefin porous membranes (PE, PP, such as Daramic membrane), perfluorosulfonic acid proton exchange membranes (Nafion series) or sulfonated polyether ether ketone membranes (SPEEK).

[0028] The zinc-bromine flow battery operates as follows: The electrolyte in the negative electrode electrolyte storage tank 3 enters the negative electrode 1 through the negative electrode peristaltic pump 6. When the zinc ions in the electrolyte flow through the negative electrode 1, an electrochemical deposition / dissolution reaction occurs on the surface of the morphology-customized zinc-loving metal array and within the nano-confined gaps as described in this invention. Afterward, the electrolyte flows out of the negative electrode 1 and re-enters the negative electrode electrolyte storage tank 3. The electrolyte in the positive electrode electrolyte storage tank 4 enters the positive electrode 2 through the positive electrode peristaltic pump 7. The bromide ions / bromine in the electrolyte undergo a redox reaction on the surface of the positive electrode 2. Afterward, the electrolyte flows out of the positive electrode 2 and re-enters the positive electrode electrolyte storage tank 4. Because of the presence of the separator 5, the negative electrode electrolyte on the surface of the negative electrode 1 and the positive electrode electrolyte on the surface of the positive electrode are spatially isolated from each other, preventing the bromine generated at the positive electrode from directly diffusing to the negative electrode and corroding the zinc layer. Only specific ions (such as zinc ions, potassium ions, etc.) can pass through the separator to maintain charge balance.

[0029] The beneficial technical effects of the present invention are as follows: This invention proposes for the first time a zinc-based flow battery anode interface modification system based on the synergistic effect of zinc-loving metal induction and nanoconfinement, and provides a feasible technical solution for realizing this system, filling the gap in existing flow battery anode interface control technology under high areal capacity and strong shear conditions. Compared with traditional single zinc-loving coatings or conventional porous electrode systems, the in-situ grown nanoarray structure constructed in this invention fundamentally eliminates the failure caused by the peeling of the active layer under the dual stress of fluid scouring and volume expansion, and has inherent advantages such as strong interfacial bonding, low induced nucleation energy barrier, and strong physical confinement capability.

[0030] This invention addresses key issues such as high overpotential for zinc ion crystal nucleation, uncontrolled dendrite growth in deep deposition, and easy shedding of hydrophobic zinc layers by constructing a customized zinc-loving metal array. This enables the zinc-bromine flow battery system, which has an inherent cost advantage, to achieve stable operation with ultra-high cumulative deposition capacity, providing a new solution for large-scale, long-term energy storage. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of the aqueous zinc-bromine flow battery provided by the present invention.

[0033] Figure 2The images are SEM images of TGF (a) and PGF (b) in Comparative Example 1, Bi NS@TGF-2 (c) in Example 1, Bi NS@TGF-4 (d) in Example 2, Bi NS@TGF-6 (e) in Example 3 and Bi NS@TGF-8 (f) in Example 4.

[0034] Figure 3 The results show the coulombic efficiency, voltage efficiency, and energy efficiency of the negative electrode materials prepared in Comparative Example 1 and Examples 1-4 of this invention.

[0035] Figure 4 The results of the cycle performance test of Bi NS@TGF-4 prepared in Example 2 of this invention are shown. Detailed Implementation

[0036] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0037] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0038] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0040] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0041] Unless otherwise specified, room temperature in this invention refers to a temperature of 20±10℃.

[0042] Comparative Example 1 Heat-treated graphite felt electrode (blank control): Commercial polyacrylonitrile-based graphite felt (PGF) was cut into 2×2.5cm pieces. 2The graphite felt was ultrasonically cleaned for 30 minutes each in anhydrous ethanol and deionized water to remove surface oil and impurities. The cleaned graphite felt was then dried in a forced-air drying oven and subsequently transferred to a muffle furnace for heat treatment at 500°C for 5 hours in air. After natural cooling to room temperature, the heat-treated graphite felt electrode (TGF) was obtained.

[0043] The SEM image of TGF in Comparative Example 1 is shown below. Figure 2 In the middle (a), the SEM image of PGF is shown below. Figure 2 (b)

[0044] Battery Assembly and Testing: Zinc-bromine flow battery single cells were assembled using the prepared TGF as both the positive and negative electrodes. A porous polyolefin membrane was used as the battery separator, and the electrolyte was a mixed aqueous solution of 2 mol / L zinc bromide (ZnBr2), 3 mol / L potassium chloride (KCl), and 0.4 mol / L N-methyl-N-ethylpyrrolidine ammonium bromide (MEP). To evaluate the performance of the reference electrode, constant current charge-discharge tests were performed under a fixed charging capacity of 100 mAh at a deep deposition level. The test results for coulombic efficiency, voltage efficiency, and energy efficiency are shown below. Figure 3 ,like Figure 3 As shown, at 100mA / cm 2 At a given current density, the coulombic efficiency (CE) of the TGF is 97.92%, but its voltage efficiency (VE) is only 78.49%, resulting in a low energy efficiency (EE) of 76.86%. This data indicates that, due to the lack of zinc-loving sites and an effective physical confinement structure, zinc deposition on bare carbon substrates faces a huge nucleation energy barrier and concentration polarization, resulting in severe voltage hysteresis during charging and discharging, which cannot meet the requirements for efficient energy storage.

[0045] Example 1 Preparation of low-concentration in-situ grown bismuth nanosheet array modified electrode (Bi NS@TGF-2): Measure 50 mL of ethylene glycol (EG) into a beaker, weigh 2 mmol of bismuth nitrate pentahydrate (Bi(NO3)3·5H2O) and 10 mmol of ammonium chloride (NH4Cl) and add them to the beaker. Stir until completely dissolved to form a clear precursor solution. The sample prepared according to Comparative Example 1 has a size of 2 × 2.5 cm. 2 TGF-based substrates were immersed in a precursor solution and transferred to a hydrothermal reactor for reaction at 180°C for 20 h, allowing the precursor to grow in situ on the fiber surface. After the reaction, the substrate was washed with ethanol and water, followed by electrochemical reduction in a three-electrode system (1 MkOH electrolyte) with a constant potential of -1.3 V (vs. SCE). After washing and drying, BiNS@TGF-2 was obtained.

[0046] The SEM image of BiNS@TGF-2 in Example 1 is shown below. Figure 2 (c) For example Figure 2 As shown in the microstructure characterization in (c), due to the low precursor concentration, although the bismuth on the electrode surface forms a nanosheet structure, it exhibits a randomly dispersed state and fails to construct a coherent array, resulting in a weak physical confinement effect. Statistical measurements indicate that the average thickness of the nanosheets is approximately 3.2 nm, and the height is approximately 155 nm. Due to the sparse distribution, the gaps between the nanosheets are relatively large, approximately 420–480 nm.

[0047] Battery Assembly and Testing: Using this electrode as the negative electrode and TGF as the positive electrode, the battery was assembled using the same electrolyte as Comparative Example 1 (2M ZnBr2 + 3M KCl + 0.4M MEP), and the testing conditions were the same as Comparative Example 1. The test results for coulombic efficiency, voltage efficiency, and energy efficiency are shown below. Figure 3 ,like Figure 3 As shown, at 100mA / cm 2 At this level, its CE was 97.79%, VE was 78.63%, and EE was 76.89%. Compared with TGF, its voltage efficiency was slightly improved. This indicates that sparsely dispersed nanosheets cannot provide enough inducing sites to reduce the overall overpotential, nor do they have effective physically confined channels to improve mass transfer, thus the modification effect is minimal.

[0048] Example 2 Preparation of in-situ grown bismuth nanosheet array modified electrode (Bi NS@TGF-4) with medium and low concentrations: Measure 50 mL of ethylene glycol (EG) into a beaker, weigh 4 mmol of Bi(NO3)3·5H2O and 10 mmol of NH4Cl into it, and stir to dissolve. Subsequent hydrothermal growth and electrochemical reduction steps are the same as in Example 1, at a 2×2.5 cm... 2 BiNS@TGF-4 was prepared on the substrate.

[0049] The SEM image of BiNS@TGF-4 in Example 2 is shown below. Figure 2 (d) For example Figure 2 As shown in the microstructure of (d), the BiNS@TGF-4 electrode surface exhibits an optimally shaped array of oriented nanosheets with moderate thickness and open, regularly spaced physical confinement gaps between adjacent nanosheets. Statistical measurements indicate that the average thickness of the nanosheets is approximately 6.5 nm, the nanosheet height is approximately 175 nm, and regular ion transport channels are formed between adjacent nanosheets, with an average gap width of 120–150 nm.

[0050] Battery assembly and testing: Battery assembly and testing conditions are the same as in Example 1. Test results for coulombic efficiency, voltage efficiency, and energy efficiency are shown below. Figure 3 ,like Figure 3As shown, at 100mA / cm 2 At this concentration, its CE is 97.68%, VE is as high as 85.48%, and EE reaches 83.51%. Compared with TGF, its voltage efficiency is significantly improved by nearly 7%, and its energy efficiency is improved by about 6.6%. This proves that the nano-confined array constructed at this concentration achieves the optimal balance between "thermodynamic induction" and "kinetic mass transfer," significantly reducing electrochemical polarization, and is the best-performing embodiment in terms of overall performance. Cyclic performance test results are shown in [link to test results]. Figure 4 ,like Figure 4 As shown, Bi NS@TGF-4 exhibits excellent stability in long-cycle testing with a fixed capacity of 100mAh, with no significant degradation after more than 7700 cycles.

[0051] Example 3 Preparation of medium-to-high concentration in-situ grown bismuth nanosheet array modified electrode (Bi NS@TGF-6): Measure 50 mL of ethylene glycol (EG) into a beaker, weigh 6 mmol of Bi(NO3)3·5H2O and 10 mmol of NH4Cl into it, and stir to dissolve. Subsequent hydrothermal growth and electrochemical reduction steps are the same as in Example 1, at a 2×2.5 cm... 2 BiNS@TGF-6 was prepared on the substrate.

[0052] The SEM image of BiNS@TGF-6 in Example 3 is shown below. Figure 2 (e) For example Figure 2 The microscopic characterization in (e) shows that as the concentration increases, the nanosheet array on the electrode surface becomes denser, and the nanosheet gaps become very narrow (<50 nm). Statistical measurements show that the average thickness of the nanosheets increases to approximately 9.1 nm, and the height of the nanosheets is approximately 195 nm, at which point the gaps between the nanosheets are compressed to the range of 30–45 nm.

[0053] Battery assembly and testing: Battery assembly and testing conditions are the same as in Example 1. Test results for coulombic efficiency, voltage efficiency, and energy efficiency are shown below. Figure 3 ,like Figure 3 As shown, at 100mA / cm 2 At this level, its CE was 96.83%, VE was 83.67%, and EE was 81.02%. Although its voltage efficiency was still significantly better than TGF and Bi NS@TGF-2, it was lower than Bi NS@TGF-4 (85.48%). This indicates that although the narrow nano-gap enhances the confinement ability, it also increases the resistance to ion transport within the channel, resulting in a slight increase in concentration polarization. At the same time, the dense structure may slightly reduce the utilization rate of the active material.

[0054] Example 4 Preparation of high-concentration in-situ grown bismuth nanosheet array modified electrode (Bi NS@TGF-8): Measure 50 mL of ethylene glycol (EG) into a beaker, weigh 8 mmol of Bi(NO3)3·5H2O and 10 mmol of NH4Cl into it, and stir to dissolve. Subsequent hydrothermal growth and electrochemical reduction steps are the same as in Example 1, at a 2×2.5 cm... 2 Bi NS@TGF-8 was prepared on the substrate.

[0055] The SEM image of BiNS@TGF-8 in Example 4 is shown below. Figure 2 (f) For example Figure 2 As shown in the microscopic characterization in (f), excessively high concentrations lead to uncontrolled growth of nanosheets and their stacking into spherical aggregates, resulting in the loss of regular nano-confined channels and an inability to maintain the preferred nanoarray size range described above. Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The test results for coulombic efficiency, voltage efficiency, and energy efficiency are shown in [reference needed]. Figure 3 ,like Figure 3 As shown, at 100mA / cm 2 Below this value, its CE is 97.41%, VE is 83.22%, and EE is 81.06%. Its voltage efficiency is lower than that of BiNS@TGF-4 and BiNS@TGF-6. This is because the spherical stacked structure blocks the originally open ion transport channels, making electrolyte penetration difficult and leading to increased local polarization, thus failing to utilize the advantages of high loading capacity.

[0056] Example 5 Preparation of in-situ grown indium nanosheet array modified electrode (In NS@TGF): 50 mL of a mixed solvent of deionized water and ethanol (volume ratio 1:1) was placed in a beaker. 4 mmol of indium chloride (InCl3) and 8 mmol of sodium citrate (as a crystal plane guiding agent) were weighed and added to the solution, and stirred to dissolve and form a clear precursor solution. A porous conductive substrate was immersed in the solution and transferred to a hydrothermal reactor for reaction at 160 °C for 10 h, allowing the precursor to grow directionally on the fiber surface. Subsequent cleaning and electrochemical reduction steps were the same as in Example 1, resulting in the preparation of In NS@TGF on the substrate.

[0057] Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The In NS@TGF electrode, thanks to the extremely high hydrogen evolution overpotential of indium metal, significantly suppressed side reactions. Specific battery performance data (coulombic efficiency, voltage efficiency, and energy efficiency) are listed in Table 1.

[0058] Example 6 Fabrication of in-situ grown tin nanosheet array modified electrode (Sn NS@TGF): 50 mL of ethanol was placed in a beaker, and 5 mmol of stannous chloride dihydrate (SnCl2·2H2O) and 10 mmol of urea were weighed and added to the beaker, and stirred to dissolve. The substrate was immersed in the mixture and then transferred to a reaction vessel, where a solvothermal reaction was carried out at 180 °C for 12 h to generate a tin oxide precursor array. Subsequently, an electrochemical in-situ reduction method was used to convert the oxide into metallic tin in an acidic electrolyte. After washing and drying, SnNS@TGF was obtained.

[0059] Battery assembly and testing: The battery assembly and testing conditions were the same as in Example 1. The Sn NS@TGF electrode utilizes the excellent alloying effect between tin and zinc (forming a Sn-Zn alloy), effectively reducing the nucleation energy barrier for zinc deposition. Specific battery performance data are listed in Table 1.

[0060] Example 7 Preparation of in-situ grown antimony nanosheet array modified electrode (Sb NS@TGF): 50 mL of ethylene glycol (EG) was placed in a beaker, and 3 mmol of antimony trichloride (SbCl3) and 0.5 g of polyvinylpyrrolidone (PVP, as a dispersant) were weighed and added to the beaker. The mixture was stirred until completely dissolved. The substrate was immersed in the solution and subjected to a solvothermal reaction at 160 °C for 12 h. Antimony ions were directly reduced and anchored to the substrate surface using the reducing properties of the polyol, thus obtaining Sb NS@TGF.

[0061] Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The Sb NS@TGF electrode effectively suppressed longitudinal dendrite penetration by inducing zinc epitaxial growth, exhibiting excellent structural stability. Specific battery performance data are listed in Table 1.

[0062] Example 8 Preparation of in-situ grown copper nanosheet array modified electrode (Cu NS@TGF): 50 mL of deionized water was placed in a beaker, and 5 mmol of copper nitrate (Cu(NO3)2·5H2O) was added. Ammonia was added dropwise to adjust the pH to 10 to form a copper-ammonia complex. The substrate was placed in the mixture, and the precursor was grown by hydrothermal reaction at 120 °C for 6 h. The subsequent electrochemical reduction steps were the same as in Example 1 to obtain Cu NS@TGF.

[0063] Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The Cu NS@TGF electrode exhibits excellent conductivity, significantly reducing local current density and ohmic polarization, demonstrating outstanding performance in high-power output scenarios. Specific battery performance data are listed in Table 1.

[0064] Example 9 Preparation of in-situ grown silver nanosheet array modified electrode (Ag NS@TGF): 50 mL of deionized water was placed in a beaker, and 2 mmol of silver nitrate (AgNO3) and an appropriate amount of ethylenediamine were added as ligands. Using a chemical bath deposition method, the substrate was vertically immersed in the solution, and sodium borohydride solution was slowly added dropwise in a 60℃ water bath for in-situ reduction growth. After washing and drying, AgNS@TGF was obtained.

[0065] Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The Ag NS@TGF electrode combines excellent zinc affinity and conductivity, minimizing deposition overpotential and exhibiting excellent overall energy efficiency. Specific battery performance data are listed in Table 1.

[0066] Example 10 Preparation of in-situ grown germanium nanosheet array modified electrode (Ge NS@TGF): 50 mL of anhydrous ethanol was placed in a beaker, and 4 mmol of germanium tetrachloride (GeCl4) was added. The mixture was stirred and hydrolyzed to form a colloidal solution. The substrate was then impregnated and placed in a reaction vessel, where a solvothermal reaction was carried out at 180 °C to generate germanium oxide nanosheets. Subsequently, the nanosheets were annealed and reduced in a tube furnace at 450 °C for 2 h under a H2 / Ar atmosphere to obtain Ge NS@TGF.

[0067] Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The unique semiconductor electronic structure of the Ge NS@TGF electrode effectively modulated the interfacial electric field distribution, achieving uniform zinc deposition. Specific battery performance data are listed in Table 1.

[0068] Example 11 Preparation of in-situ grown lead nanosheet array modified electrode (Pb NS@TGF): 50 mL of deionized water was placed in a beaker, and 5 mmol of lead acetate (Pb(CH3COO)2) and 10 mmol of thiourea were weighed and added. After immersing the substrate, a hydrothermal reaction was carried out at 160 °C for 8 h. After the reaction was completed, the electrode was annealed in air to convert it into an oxide, and then electrochemically reduced to obtain Pb NS@TGF.

[0069] Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The Pb NS@TGF electrode exhibited strong hydrogen evolution suppression capabilities similar to indium and good stability under high areal capacity deposition. Specific battery performance data are listed in Table 1.

[0070] Example 12 Preparation of in-situ grown zinc nanosheet array modified electrode (Zn NS@TGF): 50 mL of deionized water was placed in a beaker, and 0.1 mol of zinc acetate (Zn(CH3COO)2) and 5 mmol of ethylenediamine were added as morphology control agents. The substrate was used as the working electrode, and the zinc sheet was used as the counter electrode. Deposition was carried out at a constant potential of -1.2 V (vs. SCE) for 10 minutes. After cleaning and drying, a hexagonal zinc nanosheet array was grown in situ on the substrate surface to obtain Zn NS@TGF.

[0071] Battery assembly and testing: Battery assembly and testing conditions are the same as in Example 1. The Zn NS@TGF electrode utilizes a homoepitaxial growth mechanism, eliminating the nucleation barrier and achieving a transition from "surface deposition" to "bulk deposition". Specific battery performance data are listed in Table 1.

[0072] Example 13 Preparation of in-situ grown gold nanosheet array modified electrode (Au NS@TGF): 50 mL of deionized water was placed in a beaker. The substrate was first immersed in a 0.01 M chloroauric acid solution to adsorb seed crystals, and then transferred to a growth solution containing 0.02 M chloroauric acid and 0.1 MCTAB (hexadecyltrimethylammonium bromide). A trace amount of ascorbic acid was added at 30 °C and the reaction was allowed to proceed for 4 hours to allow gold to grow in a directional manner. After washing and drying, Au NS@TGF was obtained.

[0073] Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The Au NS@TGF electrode, thanks to gold's excellent conductivity and zinc affinity, minimized polarization voltage and, despite its higher cost, exhibited extremely high energy efficiency. Specific battery performance data are listed in Table 1.

[0074] Example 14 Preparation of in-situ grown cadmium nanosheet array modified electrode (Cd NS@TGF): 50 mL of deionized water was placed in a beaker to prepare a solution containing 0.05 M cadmium chloride (CdCl2) and 0.1 M ammonium chloride, and the pH was adjusted to 2. Using the substrate as the working electrode, pulse deposition was performed at -0.8 V (vs. SCE) for 20 minutes. After washing and drying, Cd NS@TGF was obtained.

[0075] Battery assembly and testing: Battery assembly and testing conditions were the same as in Example 1. The Cd NS@TGF electrode exhibits high hydrogen evolution overpotential characteristics similar to indium and bismuth, effectively suppressing hydrogen evolution side reactions and maintaining high coulombic efficiency at high current densities. Specific battery performance data are listed in Table 1.

[0076] Table 1 The results of the examples show that the composite negative electrode material of the present invention for aqueous zinc-bromine flow batteries uses porous conductive materials such as graphite felt and carbon felt as substrates, and constructs a customized zinc-loving metal array through in-situ growth technology. The zinc-loving metal is selected from one or more of Bi, In, Sn, Sb, Ag, Cu, Au, Pb, Cd, Ge, and Zn. (The examples use preferred bismuth nanosheets as an example). To verify the universality of the technical solution of the present invention, Examples 5-14 further verified other zinc-loving metals besides the preferred metal bismuth (Bi). The test results show that different metal components significantly improve battery performance through the nanoarray structure of the present invention: among them, metals such as In, Pb, Cd, and Zn, due to their high hydrogen evolution overpotential or homoepitaxial growth advantages, achieve performance at 100 mA / cm². 2 Excellent coulombic efficiency (CE above 98%) was achieved at high current densities; highly conductive metals such as Ag, Cu, and Au significantly reduced electrode polarization, exhibiting extremely high voltage efficiency (VE above 86%); metals such as Sn, Sb, and Ge also maintained a high battery energy efficiency (EE) of 78%–82% through alloying effects or electronic structure modulation. Although the energy efficiencies of Ag (EE≈85.06%) and Au (EE≈86.73%) were slightly higher than those of Bi (EE≈83.51%), considering the cost of raw materials, environmental friendliness, and long-cycle stability, Bi remains the preferred embodiment with the most promising commercial prospects. In summary, this invention utilizes a synergistic mechanism of "low-barrier induced nucleation + uniform mass transfer through nanochannels + in-situ anchoring for shear resistance" to effectively solve key problems in zinc-based flow batteries, such as reaction kinetic stagnation, uncontrolled dendrite growth, and active material shedding (dead zinc) under high areal capacity and strong fluid shear conditions. This significantly improves the battery's voltage efficiency and cumulative deposition capacity, thereby constructing a high-efficiency, high-stability, long-life zinc-bromine flow battery system.

[0077] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A zinc-based flow battery anode material, characterized in that, The zinc-based flow battery anode material is a porous conductive substrate with an in-situ grown zinc-loving metal nanoarray. The zinc-loving metal is selected from one or more of bismuth, indium, tin, antimony, silver, copper, gold, lead, cadmium, germanium, and zinc; The nanosheets of the nanoarray have a thickness of 2–10 nm, a height of 150–200 nm, and a gap of 20–500 nm between them.

2. The zinc-based flow battery negative electrode material according to claim 1, characterized in that, The porous conductive substrate is selected from graphite felt, carbon felt, carbon cloth or carbon paper.

3. A method for preparing the zinc-based flow battery negative electrode material according to claim 1 or 2, characterized in that, Includes the following steps: First, the porous conductive substrate is hydrophilized. Then, an in-situ growth strategy is used to induce the direct nucleation of zinc-loving metal precursors on the surface of the porous conductive substrate. After the zinc-loving metal precursors are reduced, zinc-loving metal nanoarrays are formed.

4. The method for preparing the zinc-based flow battery negative electrode material according to claim 3, characterized in that, The hydrophilic treatment methods include: heat-treating the porous conductive substrate at a high temperature of 300-600°C and an oxygen content of not less than 20 vol%; or chemically oxidizing the porous conductive substrate in an acidic solution; or plasma etching the porous conductive substrate.

5. The method for preparing the zinc-based flow battery negative electrode material according to claim 3, characterized in that, The in-situ growth strategies include: hydrothermal method, solvothermal method, electrochemical deposition method, or chemical bath deposition method.

6. The method for preparing the zinc-based flow battery negative electrode material according to claim 5, characterized in that, When the zinc-loving metal is bismuth and the in-situ growth strategy is hydrothermal, the preparation steps of the zinc-loving metal precursor include: placing the porous conductive substrate on a Bi... 3+ A zinc-loving metal precursor was obtained by hydrothermal reaction at 160–240 °C for 16–24 h in a precursor solution with a concentration of 40–120 mmol / L and an ammonium chloride concentration of 100–300 mmol / L.

7. The method for preparing the zinc-based flow battery negative electrode material according to claim 3, characterized in that, The reduction methods include electrochemical reduction or thermal reduction.

8. An aqueous zinc-bromine flow battery, characterized in that, The components include: The battery comprises a positive electrode, a negative electrode, a separator, an electrolyte, a storage tank, and a drive pump; the negative electrode is made of the zinc-based flow battery negative electrode material as described in claim 1 or 2; and the electrolyte is an aqueous solution containing zinc ions and bromide ions.

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