A novel carbon capture liquid flow battery system and methods of use thereof

Abstract

This invention discloses a novel carbon-fixing flow battery system and its usage method, belonging to the field of sustainable energy technology. This system organically combines carbon dioxide conversion and energy storage, overcoming the limitations of existing flow batteries that only possess energy storage functions and rely on independent systems for carbon dioxide treatment. The system includes a charging / discharging device and at least two electrolyte storage units for storing electrolytes at different reaction stages. A switchable flow path is constructed through fluid transport components to achieve a closed-loop cycle of electrolyte charging and discharging. During charging, an oxygen evolution reaction occurs at the positive electrode and a reduction reaction occurs at the negative electrode within the charging reactor stack, realizing the conversion of applied electrical energy into chemical energy. During discharging, an oxidation reaction occurs at the negative electrode and a CO2 reduction reaction occurs at the positive electrode within the discharging reactor stack, converting it into a high-value-added chemical product, achieving carbon dioxide fixation and conversion and releasing electrical energy. This invention is applicable to various large-scale energy storage and carbon capture applications.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage and carbon resource utilization technology, and in particular relates to a novel carbon solidification flow battery system and its usage method, which is used to achieve the synergistic function of CO2 conversion and fixation and electrical energy storage. Background Technology

[0002] With the continued growth of the global economy and the ever-increasing demand for energy, the massive consumption of traditional fossil fuels has led to prominent problems such as resource depletion and environmental pollution. To achieve the goals of optimizing the energy structure and protecting the ecological environment, renewable energy sources such as wind and solar power are gradually becoming important directions for energy system development. However, renewable energy power generation is significantly affected by weather, seasons, and geographical conditions, and its output is intermittent and fluctuating, making it difficult to achieve stable and continuous power supply. This poses a major challenge to grid dispatching and system stability, and also restricts its large-scale, sustainable application.

[0003] Energy storage technology is key to addressing the volatility of renewable energy and grid integration issues. Chemical energy storage, unrestricted by specific geographical conditions, offers advantages such as flexible construction and convenient deployment, making it a key development area. Flow batteries, as a typical long-duration energy storage technology, combine advantages such as independent capacity and power design, fast response speed, long cycle life, high operational safety, and easy resource recovery. They can achieve high energy density and efficiency, making them suitable for various applications including smoothing renewable energy output, peak shaving and valley filling, emergency backup dispatch, improving power quality, and grid frequency and voltage regulation. Currently, flow batteries are being demonstrated and applied in microgrids, emergency power supplies, and large-scale energy storage systems, which is of great significance for building a new power system based on renewable energy. Therefore, developing efficient flow battery energy storage systems and expanding the technological routes and application boundaries of flow batteries have become key research directions in the fields of energy and electrochemistry.

[0004] Most current flow battery systems are built based on a single electrochemical reaction, with their core objective focused on the efficient storage and release of electrical energy. However, their capabilities in utilizing and converting chemical substances are limited, making it difficult to simultaneously fulfill the dual functions of carbon resource conversion and energy storage. For flow batteries using CO2 as a reactant, to achieve substantial carbon fixation and long-term carbon sequestration, it is necessary to break through the traditional design concept of a single redox couple system and construct a reaction system based on a novel electrochemical pathway. This would enable the discharge process to convert CO2 into stable products and achieve carbon sequestration, while the charging process would regenerate the electrolyte. Developing novel flow battery technologies that combine carbon sequestration and energy storage functions not only provides a new approach to building a synergistic energy-carbon resource utilization system but also offers important technical references for achieving energy security, CO2 emission reduction, and ecological environment improvement, demonstrating broad practical needs and application prospects. Summary of the Invention

[0005] In view of this, in order to overcome the technical bottleneck of existing flow battery systems that mainly rely on a single electrochemical reaction and are difficult to achieve simultaneous carbon fixation and energy storage, this invention proposes a novel flow electrochemical system and its application method that is suitable for coupling CO2 conversion and fixation with energy storage.

[0006] The flow battery system of this invention comprises an electrolyte storage unit, an electrolyte circulation and flow control unit, at least one discharge reactor stack, at least one charging reactor stack, and other auxiliary units. By coordinating and regulating the flow path and flow rate of the electrolyte among the functional units, the system achieves electrochemical conversion and fixation of CO2 during the discharge phase and restores and recycles the activity of the intermediate electrolyte during the charging phase, thereby constructing a continuously operating closed-loop reaction system. This system exhibits excellent adjustability in structural configuration, reaction process, and electrolyte chemical pathway, allowing the electrochemical energy storage process and carbon fixation process to proceed synergistically within the same system. Unlike traditional flow batteries that are only used for energy storage or single chemical reactions, this invention, by constructing coupled carbon conversion and energy conversion pathways within the flow battery, enables the flow battery system to simultaneously achieve CO2 conversion and fixation during energy storage and release, thereby significantly improving the system's energy utilization efficiency and carbon emission reduction benefits.

[0007] To achieve the above objectives, this invention adopts the following technical solution: a novel carbon-fixed flow battery system, comprising an electrolyte storage unit, an electrolyte circulation and flow control unit, at least one discharge reactor stack, and at least one charging reactor stack. The system regulates the flow path of the electrolyte between the units. This system operates in two coordinated stages: discharge and charging. In the discharge stage, CO2 is electrochemically reduced at the positive electrode of the stack. Depending on the reaction conditions and the electrolyte system, one or more value-added chemicals or fuels, such as formic acid, methanol, and carbon monoxide, can be selectively generated. The regenerable electrolyte on the negative electrode side is oxidized, releasing electrons and outputting electrical energy. When the electrolyte activity decreases, the charging stage begins. Under the action of external electrical energy, oxidation reactions such as oxygen evolution occur at the positive electrode, while the regenerable electrolyte on the negative electrode side is reduced to restore its activity. Through this two-stage cycle, the system achieves a closed-loop coupling of CO2 conversion and energy storage.

[0008] Furthermore, the electrolyte storage unit may include several storage tanks for storing electrolytes required for different reaction stages. The number and function of the storage tanks are not limited, and can be configured according to actual needs, such as storage tanks for gas reactions, storage tanks for active substance regeneration, and storage tanks for auxiliary reactions.

[0009] Furthermore, the discharge reactor stack can be composed of multiple discharge reaction units connected in series; CO2 can be directly introduced into the positive electrode of the reactor stack, where it undergoes a reduction reaction with the electrolyte at the positive electrode reaction interface. Depending on the reaction system and operating conditions, one or more stable products such as formic acid, methanol, and carbon monoxide can be selectively generated, thereby achieving CO2 fixation; the regenerable electrolyte on the negative electrode side undergoes a corresponding oxidation reaction to release electrons, thereby forming a current in the external circuit and outputting electrical energy.

[0010] Furthermore, the charging reactor stack can be composed of multiple charging reaction units connected in series. When the activity of the regenerable electrolyte decreases, the system switches to the charging reaction stage. Under the drive of external electrical energy, an oxygen evolution reaction or other oxidation reaction occurs on the positive electrode side to provide an electron flow, while the regenerable electrolyte on the negative electrode side undergoes a reduction reaction, so that the active components consumed in the discharge stage are regenerated, thereby restoring its reactivity.

[0011] Furthermore, both the discharge and charging reactor stacks are equipped with bipolar plates and ion exchange membranes, with ion exchange membranes installed between the bipolar plates to form independent reaction chambers. The bipolar plates not only achieve efficient conductivity and current collection but also structurally integrate the positive and negative electrodes of adjacent reaction units into a single conductive structure, thus simultaneously fulfilling both positive and negative electrode functions and improving the stack's structural compactness and current transmission efficiency. The ion exchange membranes enable selective ion migration to maintain charge balance during the reactor stack reaction process and prevent cross-contamination of active materials.

[0012] Furthermore, the electrolyte circulation and flow control unit includes circulation pipelines, circulation pumps, and flow regulation components for switching operating modes, which are used to control the delivery of electrolyte between various storage tanks and the reactor stack, thereby realizing the orderly switching of the electrical system between discharge mode and charging mode.

[0013] Furthermore, the system can be configured with an energy conversion module for processing the electrical energy output from the discharge reactor stack or providing external electrical energy to the charging reactor stack, thereby realizing the mutual conversion between chemical energy and electrical energy. The specific structural form is not intended to be a limiting feature of this invention.

[0014] Furthermore, the system may be configured with an oxygen evolution and processing unit, which may include a gas-liquid separator, a check valve and an oxygen storage tank connected in sequence, wherein the gas-liquid separator and the oxygen-generating electrolyte storage tank form a closed loop connection for separating and safely discharging or collecting the evolved gas. The specific structural form is not intended to be a limiting feature of the present invention.

[0015] Compared with the prior art, the beneficial effects of the novel carbon solid redox flow battery system and its usage method described in this invention are: 1. This invention constructs a novel carbon fixation liquid flow electrochemical system. In the discharge phase, the system completes the electrochemical conversion of CO2 and outputs electrical energy. In the charging phase, the active electrolyte is regenerated through external electrical energy. This two-stage cycle allows for repeated use of the active components, thereby achieving synergistic carbon fixation and energy storage functions within the same system.

[0016] 2. This invention offers excellent flexibility and is not limited by a fixed number of storage tanks or specific flow path configurations. Different numbers of electrolyte storage tanks and reactor stacks can be configured according to application requirements, and the reaction flow path can be flexibly adjusted, giving the carbon fixation reaction zone and energy storage reaction zone excellent scalability and modular combination capabilities, making it suitable for application scenarios of different scales and operating conditions.

[0017] 3. The novel carbon fixation flow battery system proposed in this invention can simultaneously complete CO2 fixation and energy conversion within the same electrochemical system, thereby improving the overall utilization rate of input energy and providing a new approach for the synergistic utilization of energy and carbon resources. It also has important application value for achieving energy security, CO2 emission reduction and ecological environment improvement. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] To facilitate understanding of the schematic structure, the attached diagram only shows a single unit structure within the reactor stack. In an actual system, the complete reactor stack consists of multiple such units connected in series to meet voltage and capacity requirements. In the attached diagram: Figure 1 This is a schematic diagram of the structure of a novel carbon solid flow battery system according to the present invention.

[0020] 1-CO2 input pipeline, 2-pressure regulating valve, 3-circulation pump, 4-solenoid valve, 5-CO2 reaction electrolyte storage tank, 6-discharge reactor stack, 7-discharge reactor stack positive electrode, 8-discharge reactor stack negative electrode, 9-discharge reactor stack diaphragm, 10-regenerated electrolyte storage tank, 11-charging reactor stack, 12-charging reactor stack negative electrode, 13-charging reactor stack positive electrode, 14-charging reactor stack diaphragm, 15-oxygen evolution electrolyte storage tank, 16-gas-liquid separator, 17-check valve, 18-oxygen storage tank, 19-inverter, 20-load, 21-power generation unit, 22-power line, 23-electrolyte circulation pipeline. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the drawings, and not all of them. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the invention.

[0022] See Figure 1 This embodiment mainly includes an electrolyte storage unit, an electrolyte circulation and flow control unit, at least one discharge reactor stack, and at least one charging reactor stack.

[0023] The electrolyte circulation and storage unit includes a CO2 reaction electrolyte storage tank 5, a regenerated electrolyte storage tank 10, and an oxygen evolution electrolyte storage tank 15, which respectively store the reaction electrolyte for CO2 conversion, the regenerable Zn / ZnO nanoparticle electrolyte, and the auxiliary electrolyte for the oxidation reaction during the charging stage.

[0024] The electrolyte circulation and flow control unit includes an electrolyte circulation pipeline 23, a circulation pump 3, and a solenoid valve 4. The circulation pump 3 and the solenoid valve 4 are installed on the electrolyte circulation pipeline 23. The circulation pump 3 provides the flow power for the electrolyte between each storage tank and the fuel cell reactor unit. The solenoid valve 4 controls the flow direction of the electrolyte, realizing the switching between the discharge circuit (composed of CO2 reaction electrolyte storage tank 5, discharge reactor 6, and regeneration electrolyte storage tank 10) and the charging circuit (composed of regeneration electrolyte storage tank 10, charging reactor 11, and oxygen evolution electrolyte storage tank 15), ensuring the directional flow of the electrolyte and the efficient reaction.

[0025] The two reactor stacks are a discharge reactor stack 6 and a charging reactor stack 11. For ease of understanding, the attached figures only show the structure of a single reactor stack unit of the discharge reactor stack 6 and the structure of a single reactor stack unit of the charging reactor stack 11. In the actual system, multiple units can be connected in series to form a complete reactor stack to meet the required voltage and power output.

[0026] The discharge reaction unit consists of a discharge reaction stack positive electrode 7, a discharge reaction stack negative electrode 8, and a discharge reaction stack diaphragm 9; the charging reaction unit consists of a charging reaction stack negative electrode 12, a charging reaction stack positive electrode 13, and a charging reaction stack diaphragm 14.

[0027] In the specific implementation process, the positive and negative electrodes of the battery stack can be made into bipolar plate structures as needed to simultaneously undertake the functions of electron conduction and current distribution between adjacent battery cells, thereby improving the structural compactness and energy conversion efficiency of the battery stack; the discharge reaction battery stack separator 9 and the charging reaction battery stack separator 14 are used to achieve selective ion transport to maintain the charge balance in the battery stack, while blocking the cross-contamination of substances between different electrolytes, preventing the electrolyte components from contaminating each other, and ensuring that the reaction process proceeds stably and continuously.

[0028] In some embodiments of this system, an oxygen evolution and collection unit and an electrical energy conversion and output unit may also be included to further improve the integrity of system operation and energy utilization efficiency, but this does not constitute a limitation on the system structure of the present invention.

[0029] The oxygen evolution and collection unit may include a gas-liquid separator 16, a check valve 17, and an oxygen storage tank 18, etc., for separating the oxygen generated during the charging process from the electrolyte and collecting it safely. The separated electrolyte can be returned to the oxygen evolution electrolyte storage tank 15 to maintain circulation.

[0030] The power conversion output unit may include an inverter 19, a load 20, and a power generation unit 21, used to convert the electrical energy output from the reactor stack into usable electricity during discharge, or to provide input electrical energy to the reactor stack during charging, thereby realizing the mutual conversion between electrical energy and chemical energy. The above units can be configured according to application requirements, and their presence or absence does not affect the core electrolyte circulation and reactor stack reaction mechanism of this invention.

[0031] The method of using the novel carbon solid redox flow battery system described in this invention specifically includes the following steps: Step 1: Switch solenoid valve 4 to the discharge circuit. The electrolyte in CO2 reaction electrolyte storage tank 5 is pumped to the discharge reactor stack 6. CO2 can be introduced into the positive electrode 7 of the discharge reactor stack, where a reduction reaction of CO2 occurs at the positive electrode interface to generate one or more products such as formic acid, methanol, and carbon monoxide. The Zn nanoparticle electrolyte in regenerated electrolyte storage tank 10 is pumped to the discharge reactor stack 6, where an oxidation reaction occurs at the negative electrode 8 of the discharge reactor stack to generate ZnO nanoparticles. The Zn nanoparticles in regenerated electrolyte storage tank 10 are converted into ZnO nanoparticles. Protons pass through the discharge reactor stack diaphragm 9 and enter the positive electrode 7 of the discharge reactor stack from the negative electrode 8. The entire system outputs electrical energy.

[0032] Step 2: Switch the solenoid valve 4 to the charging circuit. The ZnO nanoparticle electrolyte in the regenerated electrolyte tank 10 is pumped to the charging reactor 11, where a reduction reaction occurs at the negative electrode 12 of the charging reactor to generate Zn nanoparticles. The ZnO nanoparticles in the regenerated electrolyte tank 10 are converted into Zn nanoparticles. The electrolyte in the oxygen evolution electrolyte tank 15 is pumped to the charging reactor 11, where an oxidation reaction occurs at the positive electrode 13 of the charging reactor to generate O2. Protons pass through the charging reactor membrane 14 and enter the negative electrode 12 of the charging reactor from the positive electrode 13. The entire system is driven by external electrical energy.

[0033] Step 3: Repeat steps 1 and 2 above, alternating between charging and discharging, to achieve CO2 fixation, O2 generation, and cyclic conversion between Zn nanoparticle electrolyte and ZnO nanoparticle electrolyte.

[0034] Before system operation, all storage tanks, fuel cell stacks, circulating pumps, solenoid valves, and other equipment are assembled and inspected to ensure that each module is functioning properly and that the electrolyte circulates between the storage tanks and the fuel cell stack. The CO2 reaction electrolyte storage tank 5 uses a neutral or acidic solution as the electrolyte, and CO2 is introduced into the positive electrode 7 of the discharge reaction fuel cell stack for reaction. The regeneration electrolyte storage tank 10 uses a suspension of nano-Zn / ZnO nanoparticles as the electrolyte. The oxygen evolution electrolyte storage tank 15 uses a neutral or acidic solution as the electrolyte. Based on the selection of the above electrolytes, the electrochemical reactions in the discharge and charging phases can be represented as follows.

[0035] Discharge phase:

[0036] Charging phase:

[0037] During the discharge process, the flow battery system releases electrical energy, which is then regulated by the inverter 19 and output to the load 20. During the charging process, the generator 21 supplies power to the charging reactor 11 after being regulated by the inverter 19. The oxygen generated during the charging process is separated by the gas-liquid separator 16 and introduced into the oxygen storage tank 18 for storage via the check valve 17.

[0038] Throughout the operation, the circulating pump 3 and the solenoid valve 4 can flexibly switch between charging and discharging circuits according to the preset flow path. The system parameter changes are recorded through multi-point monitoring (such as temperature sensors, voltage and current monitoring, etc.), providing experimental data for analyzing electrochemical reaction efficiency, CO2 conversion effect and energy storage performance.

[0039] This implementation scheme, through three-tank partitioned storage and closed-loop circulation control, enables the coordinated operation of the novel flow battery in CO2 fixation and energy storage, providing a feasible practical case for further optimizing reaction conditions, improving carbon dioxide conversion efficiency and energy storage performance.

[0040] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating orientation and positional relationships are based on the orientation and positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0041] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A novel carbon-fixed flow battery system, characterized in that: It includes an electrolyte storage unit, an electrolyte circulation and flow control unit, at least one discharge reactor stack, and at least one charging reactor stack. The storage tank and the reactor stack are connected by an electrolyte circulation pipeline. The circulation of electrolyte between the above units enables the system to convert and fix CO2 and output electrical energy during the discharge phase. During the charging phase, the reactor stack restores the activity of the regenerated electrolyte and achieves energy storage by applying external electrical energy, thereby constructing a flow battery system with both CO2 fixation and electrical energy storage functions.

2. The novel carbon-fixed flow battery system according to claim 1, characterized in that: The electrolyte storage unit includes at least three electrolyte storage tanks: a CO2 reaction electrolyte storage tank (5), a regenerable electrolyte storage tank (10), and an oxygen evolution electrolyte storage tank (15), which respectively store electrolytes for CO2 electrochemical reactions, regenerable electrolytes, and electrolytes for oxygen evolution. The number, type, and arrangement of each storage tank are adjusted according to the system capacity and operating requirements.

3. The novel carbon-fixed flow battery system according to claim 1, characterized in that: The electrolyte circulation and flow control unit includes a circulation pump (3), a solenoid valve (4), and an electrolyte circulation pipeline (23), which is used to switch the electrolyte flow path under different operating modes to realize automatic or semi-automatic switching between the discharge circuit and the charging circuit.

4. The novel carbon-fixed flow battery system according to claim 1, characterized in that: The discharge reactor stack (6) includes multiple discharge reactor units connected in series or in parallel, and the charging reactor stack (11) includes multiple charging reactor units connected in series or in parallel. Each reactor unit includes a positive electrode, a negative electrode, and a membrane structure. The positive and negative current collectors are composed of bipolar plates, which are used to achieve conductivity, fluid distribution, and multi-unit integration.

5. The novel carbon-fixed flow battery system according to claim 1, characterized in that: During the discharge phase, CO2 undergoes a reduction reaction at the positive electrode (7) of the discharge reaction stack, selectively generating one or more products among formic acid, methanol, and carbon monoxide. The active ions in the regenerable electrolyte on the negative electrode (8) of the discharge reaction stack undergo an oxidation reaction to provide an electron flow, thereby achieving the synergistic process of CO2 fixation and electrical energy output.

6. The novel carbon-fixed flow battery system according to claim 1, characterized in that: During the charging phase, oxygen evolution reaction or other oxidation reactions occur at the positive electrode (13) of the charging reaction stack, and active ions in the regenerable electrolyte on the negative electrode (12) side of the charging reaction stack undergo reduction reaction to restore the active components consumed during the discharge phase, thereby realizing the recycling and regeneration of the electrolyte.

7. The novel carbon-fixed flow battery system according to claim 1, characterized in that: The system also includes an oxygen evolution and collection unit, used to separate and collect or discharge the oxygen generated during the charging reaction from the electrolyte.

8. The novel carbon-fixed flow battery system according to claim 7, characterized in that: The electrolyte is selected from other aqueous or non-aqueous electrolyte systems containing metal ion complexes, metal oxide nanoparticles, or capable of participating in CO2 conversion and reversible redox reactions.

9. The novel carbon-fixed flow battery system according to claim 7, characterized in that: The CO2 in the system enters the discharge reactor stack through gas diffusion, electrode interface reaction, dissolution mass transfer, or direct gas-liquid contact.

10. A method of using the novel carbon solid redox flow battery system as described in any one of claims 1-9, characterized in that: Step 1: Switch to the discharge circuit. CO2 is introduced into the positive electrode (7) of the discharge reaction stack, where an electrochemical reduction reaction occurs and stable and storable formic acid, methanol or carbon monoxide is generated. The stack outputs electrical energy. The negative electrode electrolyte undergoes a corresponding oxidation reaction at the negative electrode (8) of the discharge reaction stack. Hydrogen ions migrate from the negative electrode to the positive electrode through the membrane to maintain charge balance. Step 2: Switch to the charging circuit. The regenerable electrolyte after discharge enters the negative electrode (12) of the charging reactor and completes the regeneration of active materials under the action of external power. The other electrolyte undergoes an oxidation reaction at the positive electrode (13) of the charging reactor to produce oxygen. Hydrogen ions migrate from the positive electrode to the negative electrode through the membrane. Step 3: Cycle through the discharge and charge steps to allow the active components of the regenerable electrolyte to repeatedly transform between oxidized and reduced states, thereby achieving CO2 conversion and fixation, O2 generation, and electrical energy storage.

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