Positive electrode composite material of zinc-bromine battery based on pillararene and application of positive electrode composite material
By using columnar aromatic materials to form host-guest interactions with polybrominates in zinc-bromine batteries, the problem of polybrominate shuttle effect in zinc-bromine batteries is solved, thereby improving the battery's discharge capacity, cycle stability, and power density.
Patent Information
- Application Number
- CN202511753517.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-26
- Publication Date
- 2026-02-06
AI Technical Summary
The polybrominated shuttle effect in existing zinc-bromine batteries is severe, leading to increased self-discharge and continuous capacity decay. Existing methods, such as the physical confinement of porous carbon materials and electrolyte trapping agents, have limitations and cannot effectively suppress the shuttle effect or provide additional capacity contribution.
Using columnar aromatic materials as the positive electrode composite material, the cavity structure of the material allows for strong host-guest interactions with polybrominated compounds, enabling precise anchoring and regulation of reactive substances. The abundant binding sites also enhance pseudocapacitance.
It significantly suppresses the shuttle effect during charging and discharging, improves the battery's discharge capacity, cycle stability, and power density, and achieves long cycle life and high coulombic efficiency.
Smart Images
Figure CN121484032A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of new energy storage batteries, in particular to a positive electrode composite material of a zinc-bromine battery based on a pillar arene and application thereof. BACKGROUND
[0002] Zinc-bromine flow battery (ZBFB) has attracted much attention in large-scale energy storage due to its high energy density and potential low cost. The working principle of ZBFB is mainly based on the redox reaction of bromine / bromide (Brx - / Br - ) on the positive electrode side and zinc (Zn / Zn 2+ ) on the negative electrode side. However, this type of battery still faces challenges such as low discharge capacity and poor cycle performance in practical application. The main reason is that the soluble polybromide (such as Br3 - , Br5 - ) generated during charging and discharging easily penetrates the separator, causing shuttle effect, leading to accelerated self-discharge and continuous capacity decay.
[0003] To inhibit the bromine shuttle, existing research mainly focuses on two strategies: one is to use porous carbon and other host materials to physically confine polybromide; the other is to introduce chemical capture agents into the electrolyte. For example, CN117658141A discloses a MXene material and its application as a positive electrode host for zinc-bromine batteries. The material is prepared by mixing MAX phase ceramic powder with halide salt, pressing, and then etching. The preparation process is simple, does not require additional active substances, and has good practicality. MXene can effectively anchor polybromide through physical and chemical adsorption, inhibit its migration, and catalyze the redox reaction of bromine, improving the reaction kinetics, thereby achieving high cycle stability and fast electrochemical response.
[0004] Another patent CN118431529A reports the application of supramolecular bromine capture agents based on cyclodextrin and its derivatives (such as α-, β-, γ-cyclodextrin) in zinc-bromine flow batteries. Cyclodextrin molecules can capture bromine species through their cavities to form stable host-guest complex structures, thereby inhibiting bromine shuttle and volatilization, improving the coulombic efficiency and cycle stability of the battery.
[0005] However, the above methods still have certain limitations. Traditional host materials (such as porous carbon) have high specific surface area, but their pseudo-capacitance contribution is limited, and the action on polybromide is mainly physical confinement, which is prone to leakage under high current or long-term cycling conditions; while adding capture in the electrolyte can improve the anchoring effect with bromine, but it does not contribute additional capacity to the traditional positive electrode.
[0006] Therefore, developing a new positive electrode material that can not only efficiently anchor bromine species but also actively participate in electrode reactions to synergistically improve the comprehensive performance of the battery has become an important research direction in the field of zinc-bromine batteries.
[0007] As a kind of macrocyclic supramolecular host connected by para-methylene bridge between the hydroquinone units, p-phenylene columns have highly symmetrical rigid cavity structure and can form strong host-guest interaction with halogen. At present, the research of p-phenylene columns is mainly focused on chemical sensing, drug delivery and molecular machines, and there is no report on using p-phenylene columns as functional materials for electrochemical energy storage systems, especially for inhibiting bromine shuttling and enhancing electrochemical performance in zinc-bromine batteries. SUMMARY
[0008] In view of the problems of serious polybromide shuttling effect and capacity attenuation in the existing zinc-bromine battery technology, the application provides a positive electrode composite material for zinc-bromine battery, which realizes efficient and stable host-guest interaction of bromine species by using p-phenylene columns, inhibits the shuttling effect and additionally provides significant pseudo-capacitance capacity, thereby synergistically improving the overall capacity, power density and cycle stability of the battery.
[0009] To achieve the above-mentioned purpose, the technical scheme adopted by the application is: A positive electrode composite material for zinc-bromine battery based on p-phenylene columns, wherein the positive electrode composite material comprises a p-phenylene column material.
[0010] The core of the application lies in that the unique cavity structure of p-phenylene columns can synergistically improve the performance of zinc-bromine battery in two aspects: first, the cavity can have strong host-guest interaction with polybromide, realizing precise anchoring and regulation of reactive substances, which is different from the traditional imprisonment of quaternary ammonium salt complexing agent, and is a kind of anchoring based on molecular recognition, which fundamentally inhibits the shuttling effect in the charging and discharging process, and significantly improves the cycle stability; second, the structure provides rich binding sites for ions, thereby greatly improving the pseudo-capacitance contribution of the system. Based on the dual effects, the zinc-bromine battery using p-phenylene columns as the positive electrode material has achieved breakthrough progress in discharge capacity, long cycle life and coulombic efficiency.
[0011] The p-phenylene column material comprises one or more of 1,4-diethoxyp-phenylene[6]arene, 1,4-dipropoxyp-phenylene[6]arene, 1,4-dibutoxyp-phenylene[6]arene, 1,4-di(isopropoxyp-phenylene[6]arene and 1,4-di(isobutoxyp-phenylene[6]arene.
[0012] Preferably, the positive electrode composite material further comprises a conductive agent and a binder.
[0013] The conductive agent is used to build an electron conduction network, and can be selected from one or more of acetylene black, Super P, Ketjen black, carbon nanotubes, graphene and the like.
[0014] The binder is used to enhance the structural integrity of the electrode, and can be selected from one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC) and the like.
[0015] The mass ratio of the pillar arene material, the conductive agent and the binder in the positive electrode composite is (20-80):(15-70):(5-10).
[0016] The application also provides application of the positive electrode composite in preparation of a zinc-bromine battery positive electrode.
[0017] The application also provides a zinc-bromine battery positive electrode prepared from the positive electrode composite. The positive electrode composite is coated on carbon felt, graphite felt or a porous carbon current collector and dried to obtain the positive electrode. When the positive electrode composite contains a conductive agent or a binder, the positive electrode is prepared by mixing all raw materials in a solvent in a proportion, grinding or stirring to form a uniform slurry, and coating the slurry on a current collector and drying to obtain the positive electrode.
[0018] The application also provides a zinc-bromine battery comprising the positive electrode, a negative electrode, a separator, a bromine-containing positive electrode electrolyte and a zinc-containing negative electrode electrolyte; the bromine-containing positive electrode electrolyte is an aqueous solution containing one or more compounds selected from KBr, ZnBr2 and NaBr.
[0019] The zinc-containing negative electrode electrolyte is an aqueous solution containing a soluble zinc salt; the negative electrode comprises zinc foil or zinc powder; and the soluble zinc salt comprises one or more of ZnBr2, ZnSO4 and ZnCl2.
[0020] Compared with the prior art, the application has the following beneficial effects: (1) The zinc-bromine battery positive electrode material disclosed in the application innovatively utilizes the cavity of the pillar arene to interact with the polybromide to achieve efficient anchoring of bromine species, and the anchoring effect is much stronger than traditional physical adsorption, which can greatly reduce the crossover of active bromine to the negative electrode, efficiently inhibit the shuttle effect and improve the charge-discharge cycle stability.
[0021] (2) The pseudo-capacitance capacity contributed by the pillar arene itself is superimposed with the redox capacity of bromine, so that the overall discharge specific capacity of the battery is significantly improved.
[0022] (3) The battery prepared from the positive electrode material in the application has the shuttle effect effectively inhibited, the loss of positive electrode active material is reduced, the capacity retention rate of the battery is greatly improved after long-term cycling (such as >1000 cycles), and the battery exhibits excellent cycle stability. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 The images are scanning electron microscope (SEM) images of the 1,4-diethoxy columnar aromatic hydrocarbons prepared in the embodiments of the present invention at different magnifications [6].
[0024] Figure 2 This is a comparison chart of the polybromination removal efficiency in Example 1, Comparative Example 1, and Comparative Example 2.
[0025] Figure 3 Different materials in Example 1, Comparative Example 1, and Comparative Example 2 reacted with Br3 - The energy of interaction between them.
[0026] Figure 4 The cyclic voltammograms are for Example 1, Comparative Example 1, and Comparative Example 2.
[0027] Figure 5 This is a comparison of the capacitance of batteries in Example 1, Comparative Example 1, and Comparative Example 2 at different scan rates.
[0028] Figure 6 The batteries used in Example 2, Comparative Example 3, and Comparative Example 4 were tested at 0.83 A g. -1 Comparison of cycling performance at current density.
[0029] Figure 7 The batteries used in Example 2, Comparative Example 3, and Comparative Example 4 were tested at 8.3 A g. -1 Comparison of cycling performance at current density. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.
[0031] All raw materials used in the following specific embodiments were purchased from the market. The synthesis of 1,4-diethoxy column[6] aromatic material is as follows: 1,4-diethoxybenzene (0.83 g, 5 mmol), paraformaldehyde (0.46 g, 15 mmol) and 98% concentrated sulfuric acid (30 µL, 10 mol%) were mixed and ground for 10 minutes. Then, 10 mL of ethanol and 0.5 mL of water were poured into a container. The resulting precipitate was filtered and washed with ethanol several times to obtain 1,4-diethoxy column[6] aromatic. The scanning electron microscope image of the product is shown below. Figure 1 As shown.
[0032] First, prepare 5 mL of 2 mol L -1 potassium bromide, 5 mL of 2 mol L -1 hydrobromic acid and 10 mL of 0.1 mol L -1 sodium bromate solution, then put them into a 100 mL beaker, seal the beaker with a sealing film. Stir for 10 min, prepare 20 mL of 120 mmol L -1 polybromide solution, prepare the above prepared 120 mmol L -1 polybromide solution, prepare a series of polybromide solutions with different concentrations by dilution: 12 mmol L -1 , 24 mmol L -1 , 36 mmol L -1 , 48 mmol L -1 , 60 mmol L -1 Each concentration of solution is prepared in two copies, a total of 10 samples for subsequent parallel control experiments.
[0033] Example 1 Add equal mass (20 mg) of 1,4-diethoxy pillar[6]arene (hereinafter referred to as BEP6A) to five polybromide solutions with different concentrations respectively, and test their adsorption capacity by ultraviolet-visible spectroscopy after standing for 48 hours. Calculate the interaction energy between BEP6A and Br3 - by first principles (DFT).
[0034] Comparative Example 1 Add equal mass (20 mg) of activated carbon (hereinafter referred to as Carbon) to another group of polybromide solutions prepared in Example 1, and test their adsorption capacity by ultraviolet-visible spectroscopy after standing for 48 hours. Calculate the interaction energy between Carbon and Br3 - by first principles (DFT).
[0035] Comparative Example 2 Add equal mass (20 mg) of 1,4-diethoxybenzene (hereinafter referred to as DB) to another group of polybromide solutions prepared in Example 1, and test their adsorption capacity by ultraviolet-visible spectroscopy after standing for 48 hours. Calculate the interaction energy between DB and Br3 - by first principles (DFT).
[0036] The polybromide ion removal efficiency measured by ultraviolet-visible spectroscopy in Example 1, Comparative Example 1 and Comparative Example 2 is shown in Figure 2 , 24 mmol L -1 , 36 mmol L -1 , 48 mmol L -1, 48 mmol L -1 , 60 mmol L -1 , 36 mmol L -1 , 48 mmol L -1 , 60 mmol L -1 , 36 mmol L -1 , 48 mmol L -1 , 60 mmol L -1 , 36 mmol L -1 , 48 mmol L -1 , 60 mmol L -1 , 36 mmol L -1 , 48 mmol L - , 60 mmol L -1 , 36 mmol L -1 , 48 mmol L -1 , 60 mmol L
[0037] Figure 3 The energy calculation in Example 1 shows that BEP6A has the strongest interaction energy (-58.4 kcal mol - ) with Br3 -1 , which is significantly higher than Carbon (-24.7 kcal mol -1 ) in Comparative Example 1 and DB (-16.6 kcal mol -1 ) in Comparative Example 2.
[0038] The strong interaction between BEP6A and Br3 - in Example 1 is conducive to enhancing the anchoring effect of polybromide during the charging and discharging process. At the same time, compared with DB, the cavity structure formed by BEP6A significantly enhances the interaction, thereby being conducive to improving the capacity and cycle stability of the positive electrode material.
[0039] Battery assembly and performance test The carbon paper coated after mixing the different positive electrodes with the conductive agent and the binder was used as the positive electrode, zinc foil was used as the negative electrode, and glass fiber was used as the separator. Zinc sulfate and water were mixed to obtain the negative electrode electrolyte. Among them, the concentration of zinc sulfate was 2 mol L -1 Potassium bromide and water were mixed to obtain the positive electrode electrolyte. Among them, the concentration of potassium bromide was 0.5 mol L -1The assembled zinc-bromine full cells were charged and discharged in a voltage range of 0.8 to 1.85 V. For parallel comparison, the specific capacity was based on the mass of bromine, and the volume of potassium bromide added to the positive electrode of all batteries was the same (30 μL). The positive electrode of Example 2 was BEP6A, the positive electrode of Comparative Example 3 was Carbon, the positive electrode of Comparative Example 4 was DB, the positive electrode of Comparative Example 5 was 1,4-diethoxy[5]arene, the positive electrode of Comparative Example 6 was 1,4-dipropoxy[6]arene, and the positive electrode of Comparative Example 7 was 1,4-dibutoxy[6]arene.
[0040] A comparison of the cyclic voltammetry curves of Example 2 with those of Comparative Examples 3 and 4 is shown in the figure. Figure 4 .Depend on Figure 4 As can be seen, the curve in Example 2 exhibits a significantly enhanced pseudocapacitive current signal. Furthermore, Figure 5 The results of pseudocapacitive contribution analysis at different scan rates are presented, which further validate the excellent pseudocapacitive performance of Example 2. In summary, these data fully demonstrate that the BEP6A material with its unique cavity structure can induce a significantly stronger pseudocapacitive effect compared to Carbon and DB materials, which may be the key reason for its improved capacitance.
[0041] Comparison of charge-discharge cycle performance of Example 2 with Comparative Examples 3 and 4 Figure 6 As shown. In terms of initial discharge capacity, Example 2 achieved 520.7 mAh g⁻¹. -1 This is significantly higher than that of Comparative Example 3 (263.9 mAh g). -1 ) and Comparative Example 4 (435.6 mAh g) -1 Comparative Example 4, while exhibiting higher capacity during the first discharge due to its larger capacitance contribution, showed significant charge-discharge fluctuations after 80 cycles due to its weaker anchoring effect on polybrominates. In contrast, Example 2 demonstrated superior capacity performance and cycle stability thanks to the enhanced pseudocapacitive effect of the BEP6A material and the synergistic effect of its efficient anchoring of polybrominates.
[0042] To further verify the above conclusions, we conducted charge-discharge tests at a higher current density. Figure 7 The results showed that the initial discharge capacity of Example 2 was 329.2 mAh g. -1 It is still significantly higher than that of Comparative Example 3 (159.6 mAh g). -1 ) and Comparative Example 4 (237.0 mAh g) -1). Meanwhile, the cycling stability of all batteries was improved under high current conditions, which might be due to the accelerated charge-discharge rate and shortened relaxation time of polybromide, thus weakening the negative effect of shuttling. In addition, the coulombic efficiency of Example 2 was also more stable under this condition, further demonstrating its excellent electrochemical performance.
[0043] Table 1 Charge-discharge capacity comparison under 0.83 A g -1 To verify the universality of the conclusion, we compared more comparative examples (Comparative Examples 5-7). As shown in Table 1, all comparative examples showed higher capacity than the earlier Comparative Examples 3 and 4. Notably, under the condition of the same functional group, the capacity of Example 2 based on pillar[6]arene was still superior to Comparative Example 5 based on pillar[5]arene. We believe that this is mainly due to the larger cavity structure of pillar[6]arene, thus providing more efficient ion interaction. Therefore, pillar[6]arene is a better choice for the present application.
Claims
1. A positive electrode composite material for zinc-bromine batteries based on columnar aromatics, characterized in that, The cathode composite material includes columnar aromatic materials.
2. The positive electrode composite material for zinc-bromine batteries based on columnar aromatics according to claim 1, characterized in that, The columnar aromatic materials include one or more of 1,4-diethoxy columnar[6] aromatics, 1,4-diepropoxy columnar[6] aromatics, 1,4-diebutoxy columnar[6] aromatics, 1,4-di(isopropoxy) columnar[6] aromatics, and 1,4-di(isobutoxy) columnar[6] aromatics.
3. The positive electrode composite material for zinc-bromine batteries based on columnar aromatics according to claim 1, characterized in that, The positive electrode composite material also includes a conductive agent and a binder.
4. The positive electrode composite material for zinc-bromine batteries based on columnar aromatics according to claim 3, characterized in that, The conductive agent includes one or more of acetylene black, Super P, Ketjen black, carbon nanotubes, and graphene.
5. The positive electrode composite material for zinc-bromine batteries based on columnar aromatics according to claim 3, characterized in that, The adhesive is one or more of polyvinylidene fluoride, polytetrafluoroethylene, and sodium carboxymethyl cellulose.
6. The positive electrode composite material for zinc-bromine batteries based on columnar aromatics according to claim 3, characterized in that, The mass ratio of the columnar aromatic material, conductive agent and binder in the positive electrode composite material is (20-80):(15-70):(5-10).
7. The application of the cathode composite material according to any one of claims 1-6 in the preparation of the cathode of a zinc-bromine battery.
8. A positive electrode for a zinc-bromine battery, characterized in that, The positive electrode is prepared using the positive electrode composite material described in any one of claims 1-6.
9. A zinc-bromine battery, characterized in that, It includes the positive electrode, negative electrode, separator, bromine-containing positive electrode electrolyte and zinc-containing negative electrode electrolyte as described in claim 8; the bromine-containing positive electrode electrolyte is an aqueous solution containing one or more compounds including KBr, ZnBr2 and NaBr.
10. The zinc-bromine battery according to claim 9, characterized in that, The zinc-containing negative electrode electrolyte is an aqueous solution containing soluble zinc salts; the negative electrode includes zinc foil or zinc powder; the soluble zinc salts include one or more of ZnBr2, ZnSO4, and ZnCl2.