A multifunctional electrochemical system coupling a flow battery with indirect organic electrosynthesis

Abstract

This invention discloses a multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis. The multifunctional electrochemical system includes a flow battery module and an indirect electrosynthesis module. The flow battery module includes an anolyte storage tank, a cathode storage tank, a circulating pump, a battery stack, and a power source or load. This invention couples a flow battery and indirect organic electrosynthesis into a unified electrochemical system, achieving a dual breakthrough in function and technology. On the one hand, it endows the flow battery with the dual functions of "energy storage and electrosynthesis." During periods of low electricity demand, the flow battery stores excess electrical energy; when needed, it can be used to drive the indirect organic electrosynthesis reaction, effectively improving equipment utilization and reducing unit costs. On the other hand, by utilizing the stable power supply characteristics of the flow battery through the coupling mechanism, it solves the problem of unstable renewable energy supply, providing continuous power for indirect organic electrosynthesis, fundamentally addressing the pain points of existing flow batteries and direct electrosynthesis technologies.

Description

Technical Field

[0001] This invention relates to the field of electrochemical systems technology, and in particular to a multifunctional electrochemical system coupled with a flow battery and indirect organic electrosynthesis, suitable for renewable energy-driven organic synthesis and energy storage. Background Technology

[0002] In the fields of energy storage and organic synthesis, existing technologies have significant limitations. While flow batteries, with their deep charge-discharge capability and long cycle life, have secured a place in large-scale energy storage, current mainstream flow batteries, such as vanadium redox flow batteries and zinc-bromine flow batteries, generally suffer from high costs. On one hand, the key active materials in the electrolyte are expensive; for example, vanadium resources required for vanadium redox flow batteries are pricey and have limited reserves. On the other hand, core components such as ion exchange membranes not only have complex manufacturing processes and high costs, but also have limited lifespans and require periodic replacement, further increasing operating costs. Furthermore, flow batteries have a relatively simple function, only capable of storing and releasing electrical energy, and cannot be integrated with other chemical production processes. When faced with the intermittent and fluctuating nature of renewable energy generation, it is difficult to effectively convert excess electrical energy into high-value-added chemical products, resulting in limited application scenarios and low overall energy utilization efficiency.

[0003] In the field of organic synthesis, current electrocatalytic organic synthesis technologies mainly rely on direct electrosynthesis. Direct electrosynthesis involves the direct oxidation or reduction reaction of organic reactants on the electrode surface, but this method has several drawbacks. First, the reaction efficiency is low. Due to the slow adsorption and desorption processes of organic reactants on the electrode surface and the susceptibility to side reactions, the yield and selectivity of the target product are low. Second, direct electrosynthesis is difficult to integrate with renewable energy sources. The electricity generated by renewable energy sources such as solar and wind power is fluctuating and intermittent, while direct electrosynthesis reactions require stable potential and current conditions to ensure efficiency and selectivity. This prevents direct electrosynthesis technology from fully utilizing the unstable electricity generated by renewable energy sources, greatly limiting its development potential in the field of green chemistry. Furthermore, direct electrosynthesis typically requires specific electrode materials and reaction conditions, placing high demands on equipment and further increasing the complexity and cost of the process, hindering its large-scale industrial application.

[0004] In summary, the problems and causes of existing technologies are as follows: (1) The volatility of renewable energy affects the efficiency of electrosynthesis: Existing electrosynthesis is mainly a direct electrosynthesis system that relies on the power grid or direct power supply. However, the intermittency of wind and solar power generation leads to unstable reaction conditions, affecting the product yield and quality.

[0005] (2) Current status of flow battery technology: Conventional flow batteries such as all-vanadium redox flow batteries are only used for energy storage. The electrolyte does not have the function of catalyzing organic reactions, which means that the fluctuating electrical energy of renewable energy cannot be efficiently converted into chemical energy or high-value-added chemicals.

[0006] (3) The flow battery and the electrosynthesis system operate independently and lack synergistic optimization: The flow battery and the indirect organic synthesis operate independently and cannot achieve the integration of "energy storage-synthesis", resulting in low overall energy efficiency.

[0007] Therefore, there is an urgent need to develop a new technology system that can combine flow batteries with organic electrosynthesis to overcome the shortcomings of existing technologies and achieve high efficiency, low cost and adaptability to the characteristics of renewable energy. Summary of the Invention

[0008] The purpose of this invention is to provide a multifunctional electrochemical system that couples a flow battery with indirect organic electrosynthesis, in order to solve the problems of low energy utilization rate of flow batteries, low yield and selectivity of target products in direct electrosynthesis, and the inability to combine flow batteries with organic electrosynthesis.

[0009] To achieve the above objectives, the present invention provides a multifunctional electrochemical system coupling a flow battery and an indirect organic electrosynthesis module. The multifunctional electrochemical system includes a flow battery module and an indirect electrosynthesis module.

[0010] Both current flow batteries and direct electrosynthesis have certain drawbacks. Flow batteries, for example, have a single function: energy storage. During periods of low electricity demand, the equipment remains idle, leading to resource waste. Their high cost also limits their large-scale application. Direct electrosynthesis also faces numerous challenges. The intermittent nature of renewable energy supply makes the power supply unstable, severely reducing reaction efficiency. Side reactions are prone to occur on the electrode surface during direct electrosynthesis, affecting reaction selectivity and product purity, and resulting in high energy consumption. Furthermore, the complex separation process of traditional electrosynthesis products further increases production costs and resource consumption.

[0011] To address the aforementioned problems, this invention couples a flow battery with indirect organic electrosynthesis into an electrochemical system, achieving a dual breakthrough in both function and technology. On one hand, it endows the flow battery with the dual functions of "energy storage and electrosynthesis." During periods of low electricity demand, the flow battery stores excess energy; when needed, it can be used to drive organic electrosynthesis reactions, effectively improving equipment utilization and reducing unit costs. On the other hand, through the coupling mechanism, the stable power supply characteristics of the flow battery solve the problem of unstable renewable energy supply, providing continuous power for indirect organic electrosynthesis. Furthermore, it introduces a redox mediator to construct an indirect electron transfer pathway, avoiding electrode side reactions, significantly improving catalytic efficiency and product purity, while reducing dependence on precious metal catalysts. This achieves green, efficient, and low-cost organic electrosynthesis, fundamentally solving the pain points of existing technologies. Therefore, this system utilizes the energy storage capacity of the flow battery to mitigate the volatility of renewable energy sources (such as wind and solar power), while simultaneously converting electrical energy into chemical energy efficiently through indirect electrosynthesis technology.

[0012] During energy storage and release, the flow battery module charges when there is excess power (energy is stored through a redox reaction in the electrolyte) and discharges when there is insufficient power, providing a stable power source for the indirect electrosynthesis module. In the indirect electron transfer process, within the indirect electrosynthesis module, a reversible electrochemical reaction (such as V2) occurs on the electrode surface using a redox mediator. 2+ / V 3+ VO 2+ / VO2 + TEMPO + / TEMPO、PV 5+ 3Mo9 / PV 4+ 3Mo9, Mn 3+ / Mn 2+ I2 / I - Fe(CN)6 3- / Fe(CN)6 4- p-Benzoquinone / hydroquinone, PQ / HQ, methyl viologen, MV 2+ / MV + Then, the target chemical reaction (such as CO2 reduction, reduction of C=C double bonds, reduction of aldehyde groups, oxidation and cleavage of C=C single bonds, oxidation of alcohols, etc.) is driven by homogeneous catalysis, avoiding direct contact between the electrode and the reactants, thereby improving selectivity and catalyst lifetime.

[0013] Preferably, the flow battery module includes an anolyte tank, a cathode tank, a circulation pump, a battery stack, and a power source or load.

[0014] Preferably, the anolyte storage tank stores an anolyte containing active substance A, and the catholyte storage tank stores a catholyte containing active substance B. Two circulation pumps drive the anolyte and catholyte to circulate between the storage tanks and the battery stack, respectively.

[0015] Preferably, the battery stack includes a positive electrode, a negative electrode, and an ion exchange membrane.

[0016] Preferably, the power source is used for charging, and the load is used to supply power during discharging.

[0017] Preferably, the indirect electrosynthesis module includes a first indirect electrosynthesis module and a second indirect electrosynthesis module. The first indirect electrosynthesis module is disposed on one side of the anolyte storage tank and connected thereto, and the second indirect electrosynthesis module is disposed on one side of the catholyte storage tank and connected thereto.

[0018] Preferably, the first indirect electrosynthesis module contains a redox mediator A, and the second indirect electrosynthesis module contains a redox mediator B.

[0019] In this invention, the electrolyte of the flow battery module (such as polyoxometalates POMs) also serves as the redox medium for the indirect electrosynthesis module, forming a highly efficient closed loop of "electrical energy stored in electrolyte → medium-driven synthesis reaction", eliminating the additional energy consumption of medium regeneration in traditional processes.

[0020] The polyacids in the electrolyte serve a dual purpose, acting as both energy carriers and reaction media. A single input of these materials generates the dual benefits of energy storage and the synthesis of organic compounds. This not only enhances the comprehensive utilization value of the materials but also enables closed-loop operation between the flow battery and indirect organic synthesis. The aforementioned polyacid media form a closed loop between the flow battery module and the indirect electrosynthesis module. Theoretically, apart from normal aging and wear, there is almost no waste emission. This greatly reduces chemical consumption and environmental pollution, aligning with the principles of atom economy and green chemistry.

[0021] Therefore, the multifunctional electrochemical system of the present invention, which uses the above-described structure to couple a flow battery with indirect organic electrosynthesis, has the following beneficial effects: (1) This invention achieves a deep coupling between flow batteries and indirect organic electrosynthesis through the core technology breakthrough of “energy storage-synthesis” integration. The same device can switch the function mode with one click according to the power supply of renewable energy: during the peak of photovoltaic / wind power generation, the system operates in “synthesis mode”, directly using fluctuating power to drive indirect electrosynthesis reactions such as hydrogenation of phenol to cyclohexanone and oxidation of cyclohexanone to adipic acid, avoiding power waste; during low light / no wind periods, it switches to “energy storage mode” to store surplus power in the grid as a redox flow battery.

[0022] (2) The coupling system of the present invention improves the utilization rate of renewable electrical energy, and at the same time, through the catalytic characteristics of the redox medium, it significantly breaks through the bottleneck of indirect electrosynthesis efficiency. For example, the conversion rate of cyclohexanone oxidation to adipic acid is >99% and the selectivity is >98%, and the selectivity of phenol hydrogenation to cyclohexanone is >99%, thus achieving comprehensive optimization of efficiency, cost and stability.

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure and operation process of the fluid flow energy storage-indirect electrosynthesis coupling system of the present invention; Figure 2 This is a schematic diagram of the liquid flow energy storage module of the present invention; Figure 3 This is a physical image of the fluid flow energy storage module of the present invention; Figure 4 The anode was prepared in 0.1 M cyclohexanone and 0.3 M H6[PV3Mo9O] 40 Electrolyte -0.45M H4[SiW 12 O 40 LSV curves in electrolyte mixtures; Figure 5 The graph shows the FEs and selectivity results of cyclohexanone at different current densities under 0.15M phenol and 1737°C. Figure 6 The graph shows the FEs and selectivity results of cyclohexanone at different current densities under 0.1M phenol and 1737°C. Figure 7 Generate a physical image of the product for Example 2; Figure 8 The results are for the performance of the flow battery, where (a) the scan rate is 100 mV s. -1 At that time, the CV values ​​were 0.45 M H4[SiW 12 O 40 ] and 0.3M H6[PV3Mo9O 40 (b) The prepared RFB was subjected to a current density of 40 mA cm⁻¹ 2 Typical charge-discharge diagrams, (c) Coulombic efficiency of RFB, efficiency and energy efficiency of RFB batteries prepared under different charge-current densities at different voltages, (d) Coulombic efficiency and capacity retention of the prepared RFB in each cycle of 100 cycles. Detailed Implementation

[0025] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the present invention is not limited to this embodiment.

[0026] Example 1 like Figures 1-3 As shown, this embodiment provides a multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis. The multifunctional electrochemical system includes a flow battery module and an indirect electrosynthesis module.

[0027] The flow battery module includes an anolyte tank, a cathode electrolyte tank, a circulation pump, a battery stack, and a power source or load. The anolyte tank stores an anolyte containing active substance A, and the cathode electrolyte tank stores a cathode electrolyte containing active substance B. Two circulation pumps drive the anolyte and cathode electrolyte to circulate between the tanks and the battery stack, respectively. The battery stack includes a positive electrode, a negative electrode, and an ion exchange membrane. The power source is used for charging, and the load is used to supply power during discharge.

[0028] Active substance A can be H3[PMo] 12 O 40 H4[PVMo] 11 O 40 H5[PV2Mo] 10 O 40 ]、H6[PV3Mo9O 40 ]、H7[PV4Mo8O 40 ]、H8[PV5Mo7O 40 ]、H9[PV6Mo6O 40 ]、H6[P2W 18 O 62 ]、P2Mo5VW 12 P2Mo6W 12 H6[P2W 12 Mo6O 62 One or more of the following, active substance B can be H3[PMo] 12 O 40 H4[PVMo] 11 O 40 H5[PV2Mo] 10 O 40 ]、H6[PV3Mo9O 40 ]、H7[PV4Mo8O 40 ]、H8[PV5Mo7O 40 ]、H9[PV6Mo6O 40 ]、H6[P2W 18 O 62 ]、P2Mo5VW 12 P2Mo6W12 H6[P2W 12 Mo6O 62 H6[PW] 12 O 40 ]、H6[SiW 12 O 40 One or more of the following can be used: the positive electrode material can be graphite paper or titanium felt, the negative electrode material can be graphite paper, and the ion exchange membrane can be a naphthol membrane.

[0029] The indirect electrosynthesis module includes a first indirect electrosynthesis module and a second indirect electrosynthesis module. The first indirect electrosynthesis module is located on one side of the anolyte storage tank and connected to it, and the second indirect electrosynthesis module is located on one side of the catholyte storage tank and connected to it. The first indirect electrosynthesis module contains a redox medium A, and the second indirect electrosynthesis module contains a redox medium B.

[0030] Redox mediator A can be H3[PMo] 12 O 40 H4[PVMo] 11 O 40 H5[PV2Mo] 10 O 40 ]、H6[PV3Mo9O 40 ]、H7[PV4Mo8O 40 ]、H8[PV5Mo7O 40 ]、H9[PV6Mo6O 40 ]、H6[P2W 18 O 62 ]、H6[P2W 12 Mo6O 62 One or more of the following, the redox mediator B can be H3[PMo] 12 O 40 H4[PVMo] 11 O 40 H5[PV2Mo] 10 O 40 ]、H6[PV3Mo9O 40 ]、H7[PV4Mo8O 40 ]、H8[PV5Mo7O 40 ]、H9[PV6Mo6O 40 ]、H6[P2W 18 O 62 ]、H6[P2W 12 Mo6O 62 H3[PW] 12 O 40 ]、H4[SiW 12 O 40One or more of the following.

[0031] The anolyte contains the substrate to be oxidized, and the catholyte contains the substrate to be reduced and a catalyst. R can be a substance containing functional groups such as cyclohexanone, glucose, benzyl alcohol, and lactic acid, or C-C bonds or -OH groups. P can be adipic acid, formic acid, benzaldehyde, or acetic acid.

[0032] The multifunctional electrochemical system in this embodiment has different operating states during energy storage and energy release, as detailed below: 1. Peak periods for photovoltaic / wind power generation: mainly operating under a "synergistic mode" mechanism. In this mode, the multifunctional electrochemical system achieves the synthesis of the target product through a dual-chamber electrolytic cell (cell stack) separated by an ion exchange membrane. Oxidation and reduction reactions occur in the anode and cathode chambers of the dual-chamber electrolytic cell, respectively, and the redox mediators (hereinafter referred to as "mediators") are recycled. The specific process is as follows: (1) Anode chamber (oxidation reaction zone) Electrode reaction (interfacial electron transfer): The reduced mediator (Ared) in the electrolyte undergoes an oxidation reaction at the anode surface, losing electrons to form the oxidized mediator (Aox). Electrons are then transferred to the cathode through the external circuit. The electrode reaction equation is: Ared → Aox + e .

[0033] Solution reaction (homogeneous catalytic conversion): The generated strong oxidizing agent Aox undergoes a homogeneous reaction with the target substrate (cyclohexanone) in the electrolyte, oxidizing it to the target product (adipic acid); simultaneously, Aox is reduced to Ared, which re-enters the electrode reaction cycle. The reaction equation for the solution reaction is: Aox + cyclohexanone → Ared + adipic acid.

[0034] (2) Cathode chamber (reduction reaction zone) Electrode reaction (interfacial electron transfer): The oxidized mediator (Box) in the electrolyte undergoes a reduction reaction at the cathode surface, gaining electrons transferred from the external circuit to generate the reduced mediator (Bred). Electrode reaction equation: Box + e →Bred.

[0035] Solution reaction (homogeneous catalytic conversion): The generated strongly reducing Bled reacts homogeneously with the substrate (phenol) in the electrolyte, reducing it to the target product (cyclohexanone); simultaneously, Bled is oxidized to Box, returning to the electrode reaction cycle. The reaction equation for the solution reaction is: Bled + Phenol → Box + Cyclohexanone.

[0036] 2. Low light / no wind periods: Primarily operating in "energy storage mode". In this mode, the multifunctional electrochemical system switches to the working principle of a secondary battery, realizing the storage (charging) of "electrical energy-chemical energy" and the release (discharging) of "chemical energy-electrical energy" through the change of the valence state of the mediator. The specific process is as follows: (1) Charging process (electrical energy → chemical energy storage) Negative electrode (reduction reaction): The oxidized mediator Box gains electrons from the external circuit and is reduced to the high-energy reduced mediator Bred. Energy is stored in the mediator as chemical energy. The negative electrode reaction is: Box + e⁻ →Bred (energy storage).

[0037] Positive electrode (oxidation reaction): The reduced mediator Ared releases electrons to the external circuit and is oxidized to the higher-energy oxidized mediator Aox, simultaneously completing energy storage. Positive electrode reaction equation: Ared → Aox + e (Energy storage).

[0038] (2) Discharge process (chemical energy → electrical energy release) The multifunctional electrochemical system operates in the form of a "galvanic cell," where a high-energy mediator releases energy through a valence state reversal, and electrons form an electric current through an external circuit. Negative electrode (oxidation reaction): The high-energy state Aox undergoes a reduction reaction, accepting electrons and transforming into the low-energy state Ared, while releasing chemical energy (output as electrical energy). The reaction equation at the negative electrode is: Aox + e⁻ →Ared (energy release).

[0039] Positive electrode (reduction reaction): The low-energy state Bled undergoes an oxidation reaction, losing electrons and transforming into the low-energy state Box, simultaneously releasing chemical energy. Positive electrode reaction equation: Bled → Box + e (Energy release).

[0040] Example 2 The coupled synthesis of phenol → cyclohexanone → adipic acid was carried out using the multifunctional electrochemical system in Example 1.

[0041] I. System Composition This multifunctional electrochemical system includes a flow battery module and an indirect electrosynthesis module. The specific composition and material selection of each module are as follows: 1. Flow battery module The flow battery module includes an anolyte storage tank, a cathode storage tank, a first circulation pump, a second circulation pump, a battery stack, an external power supply, and a load.

[0042] Anode electrolyte storage tank: used to store anolyte, which consists of active material, substrate to be oxidized, and solvent. The active material is H6[PV3Mo9O]. 40The reaction mixture consisted of phosphovanadium molybdate (PVMO) at a concentration of 0.15–0.35 mol / L; the substrate to be oxidized was cyclohexanone at a concentration of 0.25–0.55 mol / L; and the solvent was an aqueous solution of 0–2.2 mol / L H₂SO₄ to provide an acidic reaction environment and inhibit the reaction of H₆[PV₃Mo₉O₂]. 40 Hydrolysis, while simultaneously promoting electron transfer.

[0043] Cathode electrolyte storage tank: Used to store cathode electrolyte, which consists of an active material, a substrate to be reduced, a catalyst, and a solvent. The active material is H4[SiW]. 12 O 40 The catalyst is 2 mg / mL 10% Pd / C, used to improve the selectivity of cyclohexanone; the solvent is the same as the anolyte, which is an aqueous solution of 0-2.2 mol / L H2SO4 to ensure the consistency of ion conduction in the system.

[0044] Circulation pumps: The first circulation pump is connected between the anolyte storage tank and the anode inlet of the battery stack, and the second circulation pump is connected between the catholyte storage tank and the cathode inlet of the battery stack. Both circulation pumps are corrosion-resistant peristaltic pumps with a flow rate of 6~12mL / min. They are used to drive the anolyte and catholyte to circulate between their respective storage tanks and the battery stack to ensure that the media and the substrate are in full contact.

[0045] Battery stack: includes a positive electrode, a negative electrode, and an ion exchange membrane. The positive and negative electrodes are both graphite paper with dimensions of 3×3 cm², exhibiting excellent conductivity and acid resistance. The ion exchange membrane is a naphthol membrane with a thickness of 55~85 μm, allowing H₂O to pass through. + This is done to maintain charge balance while preventing H6[PV3Mo9O] from entering the anolyte. 40 ] with H4[SiW in the catholyte 12 O 40 Cross-mixing helps prevent mediator failure.

[0046] External power supply and load: The external power supply is a photovoltaic / wind energy storage power supply, with an output voltage of 0.8~1.6V during charging; the load is an external electrical device, which is electrically connected to the battery stack during discharging to receive the electrical energy output by the system.

[0047] 2. Indirect electrosynthesis module The indirect electrosynthesis module includes a first indirect electrosynthesis module and a second indirect electrosynthesis module, which are respectively connected to the anolyte storage tank and the cathode storage tank of the flow battery module to form a material circulation loop.

[0048] The first indirect electrosynthesis module is connected to the outlet and return port of the anolyte storage tank via pipelines. It is filled with a reaction medium identical in composition to the anolyte (containing H6[PV3Mo9O]). 40 The reaction mixture consists of cyclohexanone and a 1.2-2.2 mol / L H₂SO₄ aqueous solution, and the reaction temperature is controlled at 30-80℃. In the first indirect electrosynthesis module, H₆[PV₃Mo₉O] 40 As a redox mediator A, its reduced state is PV3Mo9O. 40 6- (denoted as Ared), oxidation state is PV3Mo9O 40 5- (denoted as Aox), used to achieve the homogeneous oxidative conversion of cyclohexanone to adipic acid.

[0049] The second indirect electrosynthesis module is connected to the outlet and return port of the cathode electrolyte tank via pipelines. It is filled with a reaction medium (containing H4[SiW]) with the same composition as the cathode electrolyte. 12 O 40 The reaction mixture consists of phenol, 10% Pd / C, and 0-2.2 mol / L H2SO4 aqueous solution, with the reaction temperature controlled at 30-80℃. In the second indirect electrosynthesis module, H4[SiW]... 12 O 40 As a redox mediator, B has an oxidation state of SiW. 12 O 40 4- (denoted as Box), the reduced state is SiW 12 O 40 5- (denoted as Bred), used to achieve the homogeneous reduction conversion of phenol to cyclohexanone.

[0050] II. System Operation Mechanism 1. Peak periods for photovoltaic / wind power generation: "Synthesis mode" (coupling synthesis of phenol → cyclohexanone → adipic acid) When photovoltaic / wind power generation is at its peak, the system switches to "synthesis mode," using excess electrical energy to drive electrochemical reactions. Through the cycling of mediators A and B, the directional coupling of phenol → cyclohexanone → adipic acid is achieved. The specific process is as follows: (1) Cathode-side reaction (phenol → cyclohexanone) Step 1: Electrode reduction of medium B (within the battery stack) The cathode electrolyte enters the cathode chamber of the battery stack under the drive of the second circulation pump. Box (SiW) in the electrolyte... 12 O 40 4- A reduction reaction occurs on the surface of the graphite paper negative electrode, which acquires electrons from the external circuit and transforms into Bled (SiW). 12 O40 5- The reaction equation for this process is: SiW 12 O 40 4- +e - →SiW 12 O 40 5- .

[0051] The high porosity of the graphite paper negative electrode provides sufficient active sites for the reaction, ensuring a Box reduction efficiency of ≥95%.

[0052] Step 2: Homogeneous reduction of phenol (within the second indirect electrosynthesis module) The Bred-containing cathode electrolyte flows into the second indirect electrosynthesis module through a pipeline. Under the action of the Pd / C catalyst, Bred (SiW) 12 O 40 5- The molecule undergoes a homogeneous reaction with phenol, the substrate to be reduced. The benzene ring of the phenol molecule is selectively hydrogenated to form cyclohexanone; simultaneously, Bled is oxidized back to Box (SiW). 12 O 40 4- The reaction equation for this process is: SiW 12 O 40 5- +C6H5OH→SiW 12 O 40 4- +C6H 10 O.

[0053] After the reaction, the catholyte containing Box and cyclohexanone is returned to the catholyte storage tank via a reflux pipeline. 30% to 50% of the cyclohexanone is introduced into the anolyte storage tank through a material conveying pipeline as the substrate to be oxidized on the anode side. The remaining cyclohexanone is retained in the catholyte storage tank to continue participating in the reaction, ensuring that the substrate utilization rate is ≥90%.

[0054] (2) Anode-side reaction (cyclohexanone → adipic acid) Step 1: Electrode oxidation of medium A (within the battery stack) The anolyte enters the anode chamber of the battery stack under the drive of the first circulation pump. The anolyte contains Ared (PV3Mo9O). 40 6- On the surface of the graphite paper cathode, an oxidation reaction occurs, resulting in the loss of electrons and the conversion into Aox (PV3Mo9O). 40 5- Electrons are transferred to the cathode via an external circuit, providing an electron source for the reduction of medium B. The reaction equation for this process is: PV3Mo9O 40 6- →PV3Mo9O40 5- +e - The acidic environment of the H2SO4 aqueous solution can stabilize A. ox To understand its chemical properties and avoid side reactions.

[0055] Step 2: Homogeneous oxidation of cyclohexanone (within the first indirect electrosynthesis module) The Aox-containing anolyte flows into the first indirect electrosynthesis module through a pipeline. 40 5- Aox undergoes a homogeneous reaction with the substrate cyclohexanone, where the six-membered ring of the cyclohexanone molecule breaks and is oxidized to form adipic acid; simultaneously, Aox is reduced back to Ared (PV3Mo9O). 40 6- The reaction equation for this process is: PV3Mo9O 40 5- +C6H 10 O + 3H₂O → PV₃Mo₹O 40 6- +HOOC(CH2)4COOH+2H + .

[0056] After the reaction, the anolyte containing Ared and adipic acid is returned to the anolyte storage tank through the reflux pipeline. Adipic acid is separated by cooling crystallization (temperature controlled at 6~11℃), and the purity of the precipitated adipic acid is ≥98.5%. The mother liquor (containing Ared and unreacted cyclohexanone) continues to participate in the cycle, and the cycle life of mediator A is ≥500 times.

[0057] 2. Low light / no wind periods: "Energy storage mode" (energy storage and release) When photovoltaic / wind power generation is at its off-peak, the system switches to "energy storage mode," converting electrical energy into chemical energy through changes in the valence states of media A and B. The specific process is as follows: (1) Charging process (electrical energy → chemical energy) An external photovoltaic / wind energy storage power source supplies power to the battery stack, and a reduction reaction occurs at the negative electrode (graphite paper): Box (SiW) in the cathode liquid... 12 O 40 4- It gains electrons and transforms into Bled (SiW) 12 O 40 5- Energy is stored in the Bred as chemical energy, and the reaction is: SiW 12 O 40 4- +e - →SiW 12 O 405- (Energy storage).

[0058] Oxidation reaction occurs at the positive electrode (graphite paper): Ared (PV3Mo9O) in the anolyte 40 6- It loses electrons and transforms into Aox (PV3Mo9O). 40 5- Simultaneously, energy storage is completed, and the reaction formula is: PV3Mo9O 40 6- →PV3Mo9O 40 5- +e - (Energy storage).

[0059] (2) Discharge process (chemical energy → electrical energy) The battery stack acts as a primary cell to supply power to the load, and an oxidation reaction occurs at the negative electrode: Bred(SiW) 12 O 40 5- It loses electrons and transforms into Box (SiW) 12 O 40 4- ), releasing chemical energy, the reaction formula is: SiW 12 O 40 5- →SiW 12 O 40 4- +e - (Energy release).

[0060] A reduction reaction occurs at the positive electrode: Aox(PV3Mo9O) 40 5- It gains electrons and transforms into Ared (PV3Mo9O) 40 6- Simultaneous release of chemical energy, the reaction formula is: PV3Mo9O 40 5- +e - →PV3Mo9O 40 6- (Energy release).

[0061] To evaluate the industrial application potential of this system, a two-electrode flow electrolyzer with an effective area of ​​9 square centimeters was constructed for the electrocatalytic oxidation of phenol to adipic acid. Linear sweep voltammetry (LSV) was used for testing. Figure 4 This indicates that the paired electrolysis system only requires a battery voltage of 1.4V to achieve 0.9A (100mA·cm). - The current of 2) highlights its excellent energy efficiency.

[0062] System constant current electrolysis test ( Figure 5 , 6 This indicates that this indirect electrocatalytic system, through the decoupling design of electrode reactions and organic matter conversion reactions, can maintain high selectivity at different current densities, effectively overcoming the inherent thermodynamic mismatch between the anode and cathode in traditional direct pairing electrosynthesis.

[0063] At 100mA·cm - At a current density of 20 mA·cm², the system exhibited excellent catalytic performance: the yield of adipic acid reached 98%, while the yield of cyclohexanone was 67%, demonstrating that the cyclohexanone produced at the cathode fully met the requirements of the anolyte reaction. Notably, the Faradaic efficiency (FEs) of cyclohexanone at the cathode is related to the current density, reaching a high level at 20 mA·cm². - The current density reaches a peak of 81% at 2°C and gradually decreases with increasing current density. This phenomenon is caused by the reduction of H₄[SiW] at the cathode. 12 O 40 Heteropolyblue species are formed, releasing active hydrogen on the Pd / C surface for phenol hydrogenation, inevitably accompanied by hydrogen evolution side reactions. Notably, this system can be driven by renewable energy sources at 100 mA·cm⁻¹. - Under conditions of 2°C, continuous operation for 24 hours can produce 9.8 grams of product (e.g., ...). Figure 7 As shown in the figure, it demonstrates great potential for industrial applications.

[0064] Example 3 The flow battery (RFB) energy storage mode was tested, and the test results are shown below. Figure 8 .

[0065] The electrochemical performance of the RFB battery was evaluated at room temperature. Figure 8 To determine the performance test results of the flow battery, cyclic voltammetry (CV) tests were first performed on the anode and cathode electrolytes, such as... Figure 8 As shown in figure a, the CV results indicate that H4[SiW] 12 O 40 The sample exhibits three pairs of redox peaks. Two single-electron redox peaks are located at -0.17 V vs. Ag / AgCl and -0.42 V vs. Ag / AgCl, respectively. The third redox peak is located at -0.64 V / Ag / AgCl, corresponding to a two-electron redox reaction. During charge and discharge, the third pair of redox peaks should be avoided as it corresponds to irreversible reduction. H6[PV3Mo9O] 40 The system exhibits multiple redox peaks with a potential difference of approximately 1.34V, indicating that the system has good reversibility and a suitable operating voltage.

[0066] like Figure 8 As shown in b, in H4[SiW12 O 40 In the 2e-reduced state, at a current density of 40 mA cm⁻¹ -2 Under these conditions, typical charge-discharge curves were measured, and two voltage plateaus were observed on the curves, corresponding to two single-electrode reactions, which is consistent with the CV results of the three-electrode system. The fabricated RFB cells were then investigated at current densities ranging from 20 to 80 mA cm⁻¹. -2 Multiplier capability within the range, such as Figure 8 As shown in Figure c, the Coulombic efficiency is close to 100% at all current densities, indicating high charge transfer efficiency during charging and discharging. At 20 mA cm⁻¹ -2 At this point, the energy efficiency is approximately 82%, but due to ohmic losses, the energy efficiency decreases slightly with increasing current density. When the current density is 80 mA cm⁻¹ -2 At higher current densities, the energy efficiency drops to 62%, due to increased voltage polarization. The excellent performance of the fabricated RFB battery at various charging current densities provides more opportunities for flexible and efficient storage of intermittent wind and solar energy.

[0067] To further investigate the stability of the RFB system, at 40 mA cm -2 A constant current density was used to conduct 100 cycles of testing, such as... Figure 8 As shown in d, during long-term cycling, the coulombic efficiency remains close to 100%, and the capacity retention rate is 80%.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis, characterized in that: The multifunctional electrochemical system includes a flow battery module and an indirect electrosynthesis module.

2. The multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis according to claim 1, characterized in that: A flow battery module includes an anolyte tank, a cathode tank, a circulation pump, a battery stack, and a power source or load.

3. The multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis according to claim 2, characterized in that: The anolyte storage tank stores anolyte containing active substance A, and the catholyte storage tank stores catholyte containing active substance B. Two circulation pumps drive the anolyte and catholyte to circulate between the storage tanks and the battery stack, respectively.

4. The multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis according to claim 2, characterized in that: The battery stack includes a positive electrode, a negative electrode, and an ion exchange membrane.

5. The multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis according to claim 2, characterized in that: The power source is used for charging, and the load is used to supply power during discharging.

6. The multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis according to claim 2, characterized in that: The indirect electrosynthesis module includes a first indirect electrosynthesis module and a second indirect electrosynthesis module. The first indirect electrosynthesis module is located on one side of the anolyte storage tank and connected to it, and the second indirect electrosynthesis module is located on one side of the catholyte storage tank and connected to it.

7. The multifunctional electrochemical system coupling a flow battery and indirect organic electrosynthesis according to claim 6, characterized in that: The first indirect electrosynthesis module contains redox mediator A, and the second indirect electrosynthesis module contains redox mediator B.

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