Lithium carbon dioxide flow battery system based on double electrolytes and energy storage-carbon capture integrated method thereof

Abstract

The invention discloses a lithium carbon dioxide flow battery system based on double electrolytes and an energy storage-carbon capture integrated method thereof, and belongs to the technical field of electrochemical energy storage and carbon capture. Aqueous electrolyte (aqueous side) and organic electrolyte (organic side) are separated by a solid electrolyte diaphragm, and CO2-containing gas is directly introduced into the aqueous side, so that the CO2-containing gas is directly introduced into the organic side; an electrochemical reduction reaction is carried out to generate Li2CO3, a lithium metal negative electrode is adopted on the organic side, lithium ions are unidirectionally transmitted through a solid electrolyte diaphragm to maintain charge balance, and meanwhile corrosion of water and oxygen to the lithium metal negative electrode is isolated. In the operation process, the external pump drives the water system electrolyte to flow, generated Li2CO3 is continuously taken away from the surface of the electrode, reaction stagnation caused by product accumulation is avoided, high-purity products can be recycled through simple precipitation or filtration of enriched Li2CO3, and the residual electrolyte is reused to the system to form a closed loop. Based on the process, the lithium carbon dioxide flow battery system based on the double electrolytes can simultaneously realize continuous carbon dioxide fixation and rapid discharge.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage and carbon capture, and in particular relates to a dual-electrolyte-based lithium-carbon dioxide flow battery system and an integrated energy storage-carbon capture method thereof. Background Art

[0002] Lithium-ion batteries dominate the market, with annual shipments reaching 122GWh (2024 data). However, existing lithium battery technology can only store electrical energy in one direction and cannot directly participate in the carbon cycle, making it difficult to support the deep decarbonization needs of key industries such as thermal power and steel (which account for over 60% of China's total carbon emissions).

[0003] Lithium-carbon dioxide (Li-CO2) battery is an important technology for large-scale carbon dioxide capture and efficient electrical energy conversion. The reaction fixes CO2 as an electrical energy storage medium. Its theoretical energy density (1875Wh / kg) far exceeds that of lithium-ion batteries (<350Wh / kg). However, this technology faces three major industrial bottlenecks:

[0004] 1. Energy density is high in reality: due to CO2 mass transfer resistance (diffusion coefficient <10 -5 cm 2 / s) and product deposition, the actual discharge capacity is less than 30% of the theoretical value (<600Wh / kg);

[0005] 2. Irreversible electrode passivation: Insulating Li2CO3 (resistivity>10 8 Ω·cm) forms a dense layer on the cathode surface (thickness > 5μm after 50 cycles), resulting in a 10-fold increase in charge transfer impedance;

[0006] 3. System compatibility contradiction: The CO2 solubility in organic electrolyte is low (<0.1 mol / L), while the aqueous electrolyte will induce hydrogen evolution corrosion at the lithium negative electrode (rate >0.5 μL / min).

[0007] The research community has proposed several improvements to address these issues. For example, a Ru@MOF composite catalyst (CN114583205A) was used to reduce the CO2 reduction overpotential to 0.21V, but this was unable to prevent Li2CO3 deposition. The introduction of a solid-state electrolyte (Nature Energy, 2021, 6:987) inhibited lithium dendrite growth, but the static electrolyte design limited CO2 mass transfer. Existing technologies only optimize local reaction kinetics and remain unresolved: they ignore the fundamental issue of electrode interface deactivation caused by product deposition, making it difficult to achieve a synergistic improvement in both high energy density and long cycle life. Summary of the Invention

[0008] In order to solve the above technical problems, the present invention proposes a lithium carbon dioxide liquid flow battery system based on dual electrolyte and its integrated energy storage-carbon capture method. The lithium carbon dioxide liquid flow battery system based on dual electrolyte of the present invention is a dynamic circulation Li-CO2 carbon fixation battery device, which realizes the efficient conversion and resource recovery of CO2 in industrial exhaust gas through dual electrolyte partition design and external field driven circulation system.

[0009] To achieve the above objectives, the present invention provides the following technical solutions:

[0010] One of the technical solutions of the present invention:

[0011] The present invention provides a dual-electrolyte-based lithium-carbon dioxide flow battery system, which comprises a dual-electrolyte-based lithium-carbon dioxide flow battery, a pump, an aqueous electrolyte storage tank, and a lithium carbonate filtration and purification device.

[0012] The dual-electrolyte-based lithium-carbon dioxide flow battery comprises a positive electrode, a negative electrode, and a solid electrolyte located between the positive electrode and the negative electrode; a positive electrode cavity is formed between the positive electrode and the solid electrolyte; a negative electrode cavity is formed between the negative electrode and the solid electrolyte; the positive electrode cavity is filled with an aqueous electrolyte, and the negative electrode cavity is filled with an aqueous electrolyte;

[0013] The cathode chamber is used to introduce a gas containing CO2 to generate lithium carbonate (Li2CO3) through an electrochemical reduction reaction;

[0014] The solid electrolyte is located between the positive electrode cavity and the negative electrode cavity as a diaphragm, and is used to isolate the aqueous electrolyte from the organic electrolyte;

[0015] The negative electrode is a lithium metal negative electrode.

[0016] The present invention is based on a dual-electrolyte lithium carbon dioxide flow battery system. The solid electrolyte membrane separates the aqueous electrolyte (aqueous side) and the organic electrolyte (organic side). The gas containing CO2 (such as industrial exhaust containing CO2) is directly introduced into the aqueous side, and an electrochemical reduction reaction occurs to generate lithium carbonate (Li2CO3). The organic side uses a lithium metal negative electrode. The solid electrolyte membrane transmits lithium ions in one direction to maintain charge balance, while isolating the corrosion of the lithium metal negative electrode by water and oxygen. During operation, an external pump drives the aqueous electrolyte to flow, continuously removing the generated Li2CO3 (which is in a particle state) from the electrode surface to avoid reaction stagnation caused by product accumulation. The enriched Li2CO3 can be recovered as a high-purity product (purity can reach 95%) by simple precipitation or filtration, and the remaining electrolyte is recycled to the system to form a closed loop. Based on the above process, the present invention is based on a dual-electrolyte lithium carbon dioxide flow battery system. It can simultaneously achieve continuous carbon dioxide fixation and rapid discharge.

[0017] Exemplarily, the lithium metal negative electrode is a high-purity lithium sheet, a lithium alloy sheet, a lithium-plated copper foil or lithium iron phosphate.

[0018] Exemplarily, the gas containing CO 2 includes a mixture of oxygen and CO 2 , a mixture of water vapor and CO 2 , industrial exhaust gas containing CO 2 , or a mixture of oxygen, water vapor and CO 2 .

[0019] Further, the solvent of the organic electrolyte includes one of dimethyl sulfoxide (DMSO), tetraethylene glycol dimethyl ether (TEGDME), ethylene glycol dimethyl ether (DME) and acetonitrile (ACN);

[0020] And / or, the solvent of the aqueous electrolyte is water.

[0021] Furthermore, the lithium salt in the organic electrolyte is lithium perchlorate (LiClO4) or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI);

[0022] And / or, the lithium salt in the aqueous electrolyte is lithium chloride (LiCl), lithium nitrate (LiNO3), lithium acetate (LiCH3COO), lithium trifluoromethanesulfonate (LiOTF) or LiTFSI.

[0023] Furthermore, the solid electrolyte membrane includes lithium germanium aluminum phosphate (Li 1.5 Al 0.5 Ge 1.5 (PO4)3, one of LAGP) ceramics, lithium aluminum titanium phosphate (LATP) ceramics, lithium phosphorus oxynitride (LiPON) ceramics and lithium germanium phosphide (LGPS) ceramics, preferably LAGP ceramics.

[0024] Exemplarily, the organic electrolyte is LiClO4 / DMSO (DMSO solution containing LiClO4), LiTFSI / DMSO (DMSO solution containing LiTFSI), LiTFSI / TEGDME (TEGDME solution containing LiTFSI) or LiTFSI / DME (DME solution containing LiTFSI).

[0025] Furthermore, the organic electrolyte contains a sustained-release agent.

[0026] Exemplarily, the sustained-release agent is lithium nitrate (LiNO 3 ), and the amount of LiNO 3 added is 1%, 2% or 5% of the mass of the organic electrolyte.

[0027] Furthermore, the dual-electrolyte-based lithium carbon dioxide flow battery system also includes an aqueous electrolyte storage tank; the aqueous electrolyte storage tank and the positive electrode chamber form a circulation path through upper and lower pipelines; a pump is provided in the upper pipeline for pumping the aqueous electrolyte from the aqueous electrolyte storage tank into the positive electrode chamber; and a lithium carbonate purification device is provided in the lower pipeline for collecting and purifying the lithium carbonate produced in the positive electrode chamber.

[0028] The positive electrode is located in the positive electrode cavity, and the negative electrode is located in the negative electrode cavity.

[0029] Furthermore, the positive electrode is selected from carbon nanotube (CNT) buckypaper electrode (Ru@N-CNTs), cobalt oxide-molybdenum disulfide heterojunction / graphene foam electrode, nickel-iron alloy nanowire / boron nitride coated carbon fiber electrode or iron single atom-nitrogen doped porous carbon electrode;

[0030] And / or, the cavity material of the positive electrode cavity and the negative electrode cavity is polytetrafluoroethylene.

[0031] The second technical solution of the present invention:

[0032] The present invention provides an integrated energy storage-carbon capture method. Utilizing the above-mentioned system, CO2-containing gas is introduced into the positive electrode cavity, so that the aqueous electrolyte in the positive electrode cavity is always in a carbon dioxide saturated state; a lithium metal negative electrode is adopted on one side of the organic electrolyte, and lithium ions are unidirectionally transferred through a solid electrolyte membrane to maintain charge balance. During operation, an external pump is connected to the aqueous electrolyte storage tank, and the pump drives the aqueous electrolyte to flow, continuously carrying the generated lithium carbonate away from the electrode surface. The enriched lithium carbonate is passed through a lithium carbonate filtration and purification device to recover high-purity lithium carbonate, and the remaining electrolyte is reused in the system to form a closed loop.

[0033] Compared with the prior art, the present invention has the following advantages and technical effects:

[0034] (1) Improve reaction efficiency: The dynamic flow field design significantly accelerates the mass transfer process, alleviates electrode surface blockage, and greatly increases the CO2 reduction reaction rate; the synergistic effect of CO and O2 in the exhaust gas optimizes the product conductivity and reduces polarization loss.

[0035] (2) Achieving truly high energy density: Products are removed through electrolyte circulation to avoid ineffective deposition, and the actual energy storage density is close to the theoretical limit; the external aqueous electrolyte storage tank separates the energy storage and product recovery functions to ensure the continuous and efficient utilization of the active components of the electrolyte.

[0036] (3) Breakthrough of system compatibility limitations: The solid electrolyte membrane completely isolates water and oxygen, solving the problem of cross-contamination between organic and aqueous electrolytes.

[0037] (4) The present invention breaks through the reaction bottleneck of traditional Li-CO2 batteries, and combines high efficiency (dynamic circulation improves reaction rate), compatibility (solid-state diaphragm ensures the safety of lithium negative electrode), practicality (adaptation to low-concentration exhaust gas, simplified recovery process) and resource recycling (Li2CO3 regeneration and reuse), providing an integrated solution of "waste gas conversion-energy storage-resource regeneration" for industrial decarbonization. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0039] Figure 1 Schematic diagram of the structure of the lithium carbon dioxide flow battery system based on dual electrolyte of the present invention;

[0040] Figure 2 Comparison of the voltage-capacity curves during discharge of Example 1 and Comparative Example 1;

[0041] Figure 3 A comparison of the voltage-capacity curves during discharge of Example 2 and Comparative Example 1 is shown;

[0042] Figure 4 Comparison of the voltage-capacity curves during discharge of Example 3 and Comparative Example 1;

[0043] Figure 5 The figure is a comparison diagram of the voltage-capacity curves during the discharge process of Example 4 and Comparative Example 1. DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0046] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] The embodiment of the present invention provides a lithium carbon dioxide flow battery system based on a dual electrolyte, the structural diagram of which is shown in FIG. Figure 1 As shown, the system consists of a lithium carbon dioxide liquid flow battery based on a dual electrolyte, a pump, an aqueous electrolyte storage tank and a lithium carbonate filtration and purification device; the lithium carbon dioxide liquid flow battery based on a dual electrolyte includes a positive electrode, a negative electrode and a solid electrolyte located between the positive and negative electrodes; a positive electrode cavity is formed between the positive electrode and the solid electrolyte; a negative electrode cavity is formed between the negative electrode and the solid electrolyte; the positive electrode cavity is filled with an aqueous electrolyte, and the negative electrode cavity is filled with an aqueous electrolyte; the positive electrode cavity is used to pass CO2-containing gas to generate lithium carbonate (Li2CO3) through an electrochemical reduction reaction; the solid electrolyte is located between the positive electrode cavity and the negative electrode cavity as a diaphragm to isolate the aqueous electrolyte and the organic electrolyte; the negative electrode is a lithium metal negative electrode. The solid electrolyte separates the organic electrolyte from the aqueous electrolyte. The reaction gas (i.e., gas containing CO2) is introduced into the aqueous electrolyte to reach a saturated state. The lithium carbonate generated by the reaction dissolves into the aqueous electrolyte. Driven by a pump, it enters the lithium carbonate purification device and then enters the aqueous electrolyte tank, and is then pumped into the aqueous electrolyte to form a cycle.

[0050] The dual-electrolyte lithium-carbon dioxide flow battery system of the present invention physically isolates the aqueous electrolyte and the organic electrolyte through a solid electrolyte, and utilizes a liquid flow-driven mechanism to carry the lithium carbonate (Li2CO3) generated by the reaction away from the electrode interface in real time, thereby solving the positive electrode passivation problem of traditional lithium-carbon dioxide batteries and achieving efficient CO2 electrochemical reduction and electrical energy storage.

[0051] In an embodiment of the present invention, both the positive electrode cavity and the negative electrode cavity use polytetrafluoroethylene (PTFE) as the main material. Its chemical inertness, strong corrosion resistance and low surface energy characteristics can be compatible with the harsh environment of aqueous electrolyte (positive electrode side) and organic electrolyte (negative electrode side). The positive electrode cavity is formed into a closed cavity with a flow channel inside by injection molding or machining. The surface of the flow channel is polished to reduce the flow resistance of the electrolyte. A CO2 gas diffusion inlet is designed on the top of the cavity to ensure that the gas is evenly distributed to the carbon-based catalytic layer; a Li2CO3 suspension outlet is set at the bottom, and an external pump (circulation pump) is connected to realize real-time discharge of the product. The negative electrode cavity is made of polytetrafluoroethylene (PTFE) material for integral injection molding, and a circular groove with a depth of 2mm is formed at the bottom of the cavity by precision machining. The integrated PTFE cavity design takes into account the dual electrolyte isolation and liquid flow drive requirements.

[0052] In an embodiment of the present invention, the lithium metal negative electrode is a high-purity lithium sheet, a lithium alloy sheet, a lithium-plated copper foil or lithium iron phosphate.

[0053] In the embodiment of the present invention, illustratively, the gas containing CO 2 includes a mixture of oxygen and CO 2 , a mixture of water vapor and CO 2 , industrial tail gas containing CO 2 , or a mixture of oxygen, water vapor and CO 2 .

[0054] In an embodiment of the present invention, the solvent of the organic electrolyte includes one of dimethyl sulfoxide (DMSO), tetraethylene glycol dimethyl ether (TEGDME), ethylene glycol dimethyl ether (DME) and acetonitrile (ACN); and the solvent of the aqueous electrolyte is water.

[0055] In an embodiment of the present invention, the lithium salt in the organic electrolyte is lithium perchlorate (LiClO4) or lithium bis(trifluoromethanesulfonyl imide) (LiTFSI); the lithium salt in the aqueous electrolyte is lithium chloride (LiCl), lithium nitrate (LiNO3), lithium acetate (LiCH3COO), lithium trifluoromethanesulfonate (LiOTF) or LiTFSI. Exemplarily, the organic electrolyte is LiClO4 / DMSO (DMSO solution containing LiClO4), LiTFSI / DMSO (DMSO solution containing LiTFSI), LiTFSI / TEGDME (TEGDME solution containing LiTFSI) or LiTFSI / DME (DME solution containing LiTFSI). In the following embodiments and comparative examples of the present invention, the organic electrolyte is LiTFSI / DMSO for example, and the aqueous electrolyte is LiCl aqueous solution for example.

[0056] In an embodiment of the present invention, the organic electrolyte contains a sustained-release agent. Exemplarily, the sustained-release agent is lithium nitrate (LiNO3), and the amount of LiNO3 added is 1%, 2%, or 5% by weight of the organic electrolyte. In the following embodiments and comparative examples of the present invention, the sustained-release agent is LiNO3, and the amount of LiNO3 added is 1% by weight of the organic electrolyte.

[0057] In an embodiment of the present invention, the solid electrolyte membrane comprises lithium germanium aluminum phosphate (Li 1.5 Al 0.5 Ge 1.5 (PO4)3, one of LAGP (Lithium Aluminum Titanium Phosphate) ceramics, lithium aluminum titanium phosphate (LATP) ceramics, lithium phosphorus oxynitride (LiPON) ceramics, and lithium germanium phosphide sulfur (LGPS) ceramics, preferably LAGP ceramics. In the following embodiments and comparative examples of the present invention, LAGP ceramics are used as solid electrolyte membranes for illustration. During discharge, lithium ions move from the negative electrode to the positive electrode, thereby achieving unidirectional lithium ion transfer.

[0058] In an embodiment of the present invention, the positive electrode cavity includes a positive electrode and a cavity material, and the negative electrode cavity includes a negative electrode and a cavity material. Exemplarily, the positive electrode is selected from a carbon nanotube (CNT) buckypaper electrode (Ru@N-CNTs), a cobalt oxide-molybdenum disulfide heterojunction / graphene foam electrode, a nickel-iron alloy nanowire / boron nitride coated carbon fiber electrode or an iron single atom-nitrogen doped porous carbon electrode; Exemplarily, the cavity material is made of polytetrafluoroethylene. In the following embodiments and comparative examples of the present invention, the positive electrode is a carbon nanotube (CNT) buckypaper electrode for example; the negative electrode is a lithium sheet with a purity of 99.99% for example.

[0059] An embodiment of the present invention also provides an integrated energy storage-carbon capture method, in which a gas containing CO2 is introduced into the positive electrode cavity so that the aqueous electrolyte in the positive electrode cavity is always in a carbon dioxide saturated state; a lithium metal negative electrode is used on one side of the organic electrolyte, and lithium ions are transferred unidirectionally through a solid electrolyte membrane to maintain charge balance; an external pump is connected to the aqueous electrolyte storage tank, and the pump drives the aqueous electrolyte to flow, continuously carrying the generated lithium carbonate away from the electrode surface. The enriched lithium carbonate is passed through a lithium carbonate filtration and purification device to recover high-purity lithium carbonate, and the remaining electrolyte is reused in the system to form a closed loop.

[0060] In the following embodiments of the present invention, to prevent corrosion of the aqueous electrolyte, the aqueous electrolyte storage tank is a polytetrafluoroethylene (PVDF) aqueous electrolyte storage tank.

[0061] The present invention is based on a dual-electrolyte lithium carbon dioxide flow battery system. The solid electrolyte membrane separates the aqueous electrolyte (aqueous side) and the organic electrolyte (organic side). The gas containing CO2 (such as industrial exhaust containing CO2) is directly introduced into the aqueous side, and an electrochemical reduction reaction occurs to generate lithium carbonate (Li2CO3). The organic side uses a lithium metal negative electrode. The solid electrolyte membrane transmits lithium ions in one direction to maintain charge balance, while isolating the corrosion of the lithium metal negative electrode by water and oxygen. During operation, an external pump drives the aqueous electrolyte to flow, continuously removing the generated Li2CO3 (which is in a particle state) from the electrode surface to avoid reaction stagnation caused by product accumulation. The enriched Li2CO3 can be recovered as a high-purity product (purity can reach 95%) by simple precipitation or filtration, and the remaining electrolyte is recycled to the system to form a closed loop. Based on the above process, the present invention is based on a dual-electrolyte lithium carbon dioxide flow battery system. It can simultaneously achieve continuous carbon dioxide fixation and rapid discharge.

[0062] All raw materials used in the examples of the present invention were purchased from commercial sources. For example, carbon nanotube (CNT) buckypaper electrodes and glass fiber paper separators were purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.

[0063] It should be pointed out that the matters not described in detail in the present invention are conventional operating methods in this field and are not the focus of the present invention. For example, the specific method of pressing the lithium sheet onto the copper current collector and the method of sealing with a fluororubber O-ring are both completed using conventional methods.

[0064] The technical solution of the present invention is further illustrated by the following examples.

[0065] Example 1

[0066] This embodiment provides a lithium-carbon dioxide flow battery system based on a dual electrolyte:

[0067] The lithium carbon dioxide flow battery system based on dual electrolyte consists of a lithium carbon dioxide flow battery based on dual electrolyte, a pump, an aqueous electrolyte storage tank and a lithium carbonate filtration and purification device. The lithium carbon dioxide flow battery based on dual electrolyte includes a positive electrode, a negative electrode and a solid electrolyte located between the positive electrode and the negative electrode; a positive electrode cavity is formed between the positive electrode and the solid electrolyte; a negative electrode cavity is formed between the negative electrode and the solid electrolyte; the positive electrode cavity is filled with an aqueous electrolyte, and the negative electrode cavity is filled with an aqueous electrolyte. The positive electrode cavity is used to pass a gas containing CO2 to generate lithium carbonate (Li2CO3) through an electrochemical reduction reaction. The solid electrolyte is located between the positive electrode cavity and the negative electrode cavity as a diaphragm to isolate the aqueous electrolyte and the organic electrolyte; the negative electrode in the negative electrode cavity is a lithium metal negative electrode;

[0068] The core of the positive electrode cavity is a carbon nanotube (CNT) buckypaper electrode with a diameter of 10 mm and a thickness of 50 μm. Its porosity is 80% and the electrode loading is 5 mg / cm2 The CNT buckypaper electrode is connected to the external circuit through a titanium mesh current collector (thickness 0.1 mm) and embedded in a cavity material made of polytetrafluoroethylene (PTFE).

[0069] Lithium germanium aluminum phosphate (Li 1.5 Al 0.5 Ge 1.5 (PO4)3, LAGP) ceramic sheet is used as the solid electrolyte isolation layer, with a diameter of 12 mm, a thickness of 0.5 mm, and an ionic conductivity of 1×10 -4 S / cm, which can effectively block the direct contact between CO2 and lithium metal;

[0070] The negative electrode uses a 10mm diameter lithium sheet with a purity of 99.99%. The sheet is pressed onto a 0.2mm thick copper current collector and fixed in the negative electrode groove. It is physically isolated from the positive electrode cavity by an LAGP ceramic sheet (the LAGP ceramic sheet is sandwiched between the positive and negative electrode cavities, and the edges are sealed with a fluororubber O-ring). This ensures that lithium ions migrate only through the LAGP ceramic sheet in a directional manner, avoiding capacity decay caused by side reactions.

[0071] The organic electrolyte uses 0.05M LiTFSI / DMSO + 1% LiNO3 (i.e., the amount of LiNO3 added is 1% of the mass of the organic electrolyte) as a lithium ion transfer medium; the aqueous electrolyte is a 1M LiCl aqueous solution, which is used to dissolve and transfer the generated Li2CO3. The electrolyte is connected to the circulation pipeline through a corrosion-resistant PTFE magnetic pump (flow rate set at 3mL / min) to achieve continuous discharge of the product.

[0072] By assembling and sealing the battery system, a new lithium-carbon dioxide battery system is formed for sustainable carbon sequestration and power generation.

[0073] The integrated energy storage and carbon capture method using the above system includes the following steps:

[0074] 1. Separately introduce carbon dioxide and oxygen into the gas storage chamber at 25°C and 1 atm (the volume ratio of carbon dioxide to oxygen is 7:3) to obtain a mixed gas, which is then introduced directly into the aqueous electrolyte in the positive electrode chamber to keep the aqueous electrolyte saturated with carbon dioxide. The electrons at the positive electrode generate carbonate ions (CO3 2- );

[0075] 2. The negative electrode is a lithium sheet with a purity of 99.99%. The negative electrode undergoes an electron loss reaction to produce lithium ions. The lithium ions use the organic electrolyte as a transmission medium and migrate directionally to the positive electrode cavity through the LAGP ceramic sheet. After contacting with carbonate ions, they react to form Li2CO3. The aqueous electrolyte is connected to the circulation pipeline through a corrosion-resistant PTFE magnetic pump (the flow rate is set at 3mL / min) to achieve continuous discharge of the product.

[0076] 3. The generated Li2CO3 micron particles are precipitated in situ in DMSO and primary separation is achieved by a cyclone separator. The residual particles are retained by a 0.2μm pore size Al2O3 ceramic membrane, and the filtrate is supplemented with LiCl and then reused.

[0077] In the product recovery path of the above system, the Li2CO3 suspension discharged from the cathode cavity is transported to the solvent exchange reactor by a peristaltic pump. The solvent exchange reactor is pre-loaded with dimethyl sulfoxide (DMSO, ε=46.7) as an aprotic polar solvent. Due to the low dielectric constant of DMSO (about 50 times lower than that of aqueous electrolyte), Li + With CO3 2- The solvation layer of lithium carbonate dissociates, triggering the supersaturation critical point (Ksp from 2.5×10 -5 Down to ~10 -7 ), thereby inducing homogeneous nucleation and forming Li2CO3 crystals.

[0078] Example 2

[0079] Same as Example 1, except that the volume ratio of carbon dioxide to oxygen is 9:1.

[0080] Example 3

[0081] The same as Example 1, except that the fuel gas pressure is adjusted to 5 bar (ie, in step 1, carbon dioxide and oxygen are respectively introduced into the gas storage chamber in advance at 25° C. and 5 bar to be mixed).

[0082] Example 4

[0083] Same as Example 1, except that the aqueous electrolyte is a 5M LiCl aqueous solution.

[0084] Comparative Example 1

[0085] This comparative example is a conventional battery, i.e., a traditional static battery. The specific components and steps are as follows:

[0086] (1) Using 99.99% high-purity carbon dioxide as fuel gas;

[0087] (2) The porous carbon electrode uses a commercial buckypaper electrode with a diameter of 10 mm, a thickness of 50 μm, and a loading of 5 mg / cm 2;

[0088] (3) The lithium electrode uses commercial 99.99% high-purity metallic lithium sheets with a diameter of 10 mm;

[0089] (3) The electrolyte used was LiTFSI / DMSO with a concentration of 1 M and a dosage of 300 μL;

[0090] (5) The lithium sheet, the glass fiber paper separator soaked in LiTFSI / DMSO electrolyte, and the porous carbon electrode are stacked in sequence, and the battery is assembled and sealed to form a conventional static electrode.

[0091] The comparison of the voltage-capacity curves during discharge of Example 1 and Comparative Example 1 is shown in the figure below. Figure 2 As shown, the battery assembled in Example 1 is at 0.2 mA / cm 2 The current density shows a stable discharge voltage platform of 2.2V and a specific capacity of 10mAh / cm 2 After 50 hours of continuous operation, it still maintains an output voltage of 2.0V, with a capacity retention rate of over 95%. The performance is 50 times higher than that of Comparative Example 1, significantly breaking through the rate limit of traditional organic system lithium-CO2 batteries. The comparison of the discharge process voltage-capacity curves of Example 2 and Comparative Example 1 is shown in the figure below. Figure 3 As shown, Example 2 achieves adjustable output voltage in the range of 2.0-2.3V by regulating the CO2 / O2 mixing ratio, successfully adapting to the requirements of high-concentration CO2 waste gas treatment and variable load conditions; the comparison of the discharge process voltage-capacity curves of Example 3 and Comparative Example 1 is shown in Figure 4 As shown, Example 3 further increases the discharge voltage platform to 2.4V by optimizing the working gas pressure, verifying the synergistic enhancement effect of pressure on reaction kinetics; the comparison of the discharge process voltage-capacity curves of Example 4 and Comparative Example 1 is shown in FIG. Figure 5 As shown, Example 4 adjusts the lithium salt concentration of the aqueous electrolyte by gradient to obtain an ultra-stable reaction platform with a voltage fluctuation rate of less than 3%. The above examples jointly confirm that through the multi-phase synergistic mechanism of gaseous reactant diffusion control, liquid phase ion transport optimization and solid product deposition regulation, the battery system successfully overcomes the kinetic bottleneck of traditional lithium-CO2 batteries, and shows strong adaptability and large-scale application potential in the wide voltage window and high specific capacity range of 1.6V-2.4V for complex industrial scenarios. The battery assembled in Example 1 is at 0.2mA / cm 2 Under the current density, the discharge voltage platform is stable at 2.2V, and the specific capacity reaches 10mAh / cm 2, its rate performance is significantly improved compared to the traditional organic electrolyte system. It is particularly noteworthy that the system can still maintain an output voltage of 2.0V after 50 hours of continuous operation, and the capacity retention rate exceeds 95%, reaching 50 times the capacity level of Comparative Example 1. Example 2 further verifies the universality of this technical solution by adjusting the mixed gas ratio and operating parameters to adapt to various industrial scenario requirements (such as high CO2 concentration exhaust gas or variable load conditions). The experimental results show that the battery system successfully breaks through the kinetic bottleneck of traditional lithium-CO2 batteries through the gas-liquid-solid multiphase synergistic mechanism, showing excellent adaptability to working conditions and potential for large-scale application.

[0092] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A lithium-carbon dioxide flow battery system based on a dual electrolyte, characterized in that: The system consists of a dual-electrolyte-based lithium-carbon dioxide flow battery, a pump, an aqueous electrolyte storage tank, and a lithium carbonate filtration and purification device; The dual-electrolyte-based lithium-carbon dioxide flow battery comprises a positive electrode, a negative electrode, and a solid electrolyte located between the positive electrode and the negative electrode; a positive electrode cavity is formed between the positive electrode and the solid electrolyte; a negative electrode cavity is formed between the negative electrode and the solid electrolyte; the positive electrode cavity is filled with an aqueous electrolyte, and the negative electrode cavity is filled with an aqueous electrolyte; The cathode cavity is used to introduce gas containing CO2 to generate lithium carbonate through electrochemical reduction reaction; The solid electrolyte is located between the positive electrode cavity and the negative electrode cavity, and is used to isolate the aqueous electrolyte from the organic electrolyte; The negative electrode is a lithium metal negative electrode.

2. The dual electrolyte-based lithium carbon dioxide flow battery system according to claim 1, characterized in that: The solvent of the organic electrolyte comprises one of dimethyl sulfoxide, tetraethylene glycol dimethyl ether, ethylene glycol dimethyl ether and acetonitrile; And / or, the solvent of the aqueous electrolyte is water.

3. The dual electrolyte-based lithium carbon dioxide flow battery system according to claim 2, characterized in that: The lithium salt in the organic electrolyte is lithium perchlorate or lithium bis(trifluoromethanesulfonyl)imide; And / or, the lithium salt in the aqueous electrolyte is lithium chloride, lithium nitrate, lithium acetate, lithium trifluoromethanesulfonate or lithium bis(trifluoromethanesulfonyl)imide.

4. The dual electrolyte-based lithium carbon dioxide flow battery system according to claim 1, characterized in that: The solid electrolyte membrane comprises one of lithium germanium aluminum phosphate ceramics, lithium titanium aluminum phosphate ceramics, lithium phosphorus oxynitride ceramics and lithium germanium phosphorus sulfur ceramics.

5. The dual electrolyte-based lithium-carbon dioxide flow battery system according to claim 1, characterized in that: The aqueous electrolyte storage tank and the positive electrode chamber form a circulation passage through upper and lower pipelines; the upper pipeline is connected to the pump for pumping the aqueous electrolyte from the aqueous electrolyte storage tank into the positive electrode chamber; the lower pipeline is connected to the lithium carbonate purification device.

6. The dual electrolyte-based lithium carbon dioxide flow battery system according to claim 5, characterized in that: The positive electrode is selected from a carbon nanotube buckypaper electrode, a cobalt oxide-molybdenum disulfide heterojunction / graphene foam electrode, a nickel-iron alloy nanowire / boron nitride coated carbon fiber electrode, or an iron single atom-nitrogen doped porous carbon electrode; And / or, the cavity materials of the positive electrode cavity and the negative electrode cavity are both made of polytetrafluoroethylene.

7. The dual electrolyte-based lithium-carbon dioxide flow battery system according to claim 1, characterized in that: The organic electrolyte contains a sustained-release agent.

8. The dual electrolyte-based lithium-carbon dioxide flow battery system according to claim 7, characterized in that: The sustained-release agent is potassium nitrate.

9. An integrated energy storage and carbon capture method, characterized in that: Using the system according to any one of claims 1 to 8, a gas containing CO2 is introduced into the cathode cavity so that the aqueous electrolyte in the cathode cavity is always in a carbon dioxide saturated state; A lithium metal negative electrode is used on one side of the organic electrolyte, and lithium ions are transferred unidirectionally through a solid electrolyte membrane to maintain charge balance. An external pump is connected to the aqueous electrolyte storage tank. The pump drives the flow of the aqueous electrolyte, continuously carrying the generated lithium carbonate away from the electrode surface. The enriched lithium carbonate passes through a lithium carbonate filtration and purification device to recover high-purity lithium carbonate, and the remaining electrolyte is reused in the system to form a closed loop.

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