Preparation method and application of lithium-carbon dioxide battery positive electrode material
By loading Sn-MOF onto a wood matrix and then carbonizing it, a three-dimensional self-supporting material modified with Sn-MOF@C was prepared. This solved the problems of high overpotential and insufficient cycle performance of lithium-carbon dioxide battery cathode materials, and achieved efficient catalytic performance and long battery life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUANENG TAICANG POWER GENERATION CO LTD
- Filing Date
- 2024-11-05
- Publication Date
- 2026-05-08
AI Technical Summary
Existing lithium-carbon dioxide battery cathode materials suffer from problems such as high charging overpotential, charge-discharge specific capacity and cycle performance that need improvement, and the high cost of precious metal elements prevents their large-scale use.
Catalysts were prepared by loading Sn-MOF onto the pores of a wood matrix. Through impregnation and carbonization, a three-dimensional self-supporting material modified with Sn-MOF@C was formed, which promoted the independent growth of catalyst particles, avoided aggregation and deformation, and improved catalytic performance.
The overpotential of the lithium-carbon dioxide battery was reduced to below 3.8V, the discharge voltage was around 2.8V, the discharge specific capacity was as high as 12.86mAh/cm2, the charge specific capacity was 7.27mAh/cm2, and the cycle life reached more than 75 times, resulting in a significant performance improvement.
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Figure CN122000368A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-carbon dioxide battery electrode materials, specifically relating to a method for preparing and applying a lithium-carbon dioxide battery cathode material. Background Technology
[0002] Lithium-carbon dioxide batteries are one of the new battery systems with ultra-high energy density developed in recent years. They convert chemical energy into electrical energy and power external circuits by reacting carbon dioxide gas and lithium ions with a catalyst to produce lithium carbonate and elemental carbon. The elemental carbon produced does not participate in subsequent cycles, so it has the dual function of energy storage and carbon fixation. It is a potential system that can effectively solve energy and environmental problems at the same time.
[0003] Compared to commercially available lithium-ion batteries, lithium-carbon dioxide batteries have a higher theoretical energy density (1876 Wh·kg⁻¹). -1 ) and theoretical voltage (2.8V vs. Li / Li) + However, without a catalyst, there is a large voltage difference between the carbon dioxide reduction reaction and the carbon dioxide release reaction (typically <2.7V during discharge and >4.2V during charging), which can easily lead to reduced energy efficiency. Moreover, excessively high charging potential can easily cause electrolyte decomposition and electrode oxidation, thus limiting the development of lithium carbon dioxide batteries.
[0004] Developing efficient cathode materials is one of the key steps in promoting the development of lithium-carbon dioxide batteries. Currently, carbon nanotubes, graphene, Ketjen black, Pt, and IrO2 have been reported as cathode materials. However, precious metals such as Pt and Ir are scarce and expensive, making large-scale use impossible. Meanwhile, materials like carbon nanotubes and graphene have low energy efficiency and severe polarization, making them unsuitable for the requirements of lithium-carbon dioxide batteries. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing a positive electrode material for lithium-carbon dioxide batteries, thereby solving the problems of high charging overpotential, charge-discharge specific capacity, and cycle performance of existing lithium-carbon dioxide batteries.
[0006] The second objective of this invention is to provide the application of the lithium-carbon dioxide battery cathode material obtained by the above preparation method in lithium-carbon dioxide batteries.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0008] A method for preparing a lithium-carbon dioxide battery cathode material includes the following steps:
[0009] (1) The wood matrix after lignin removal is immersed in Sn source solution to obtain a wood matrix with Sn adsorbed.
[0010] (2) The wood matrix with Sn adsorbed is reacted with Sn source, inorganic base and organic ligand, and solid-liquid separation is performed to obtain Sn-MOF loaded wood.
[0011] (3) The Sn-MOF-loaded wood is carbonized at 650-750°C under a protective atmosphere.
[0012] This invention is groundbreaking. After removing lignin from the wood matrix, natural channels are formed, which can provide reaction sites for the generation and decomposition of discharge products. By soaking, Sn can be adsorbed onto many active sites on the wood matrix. During the synthesis of Sn-MOF nanoparticles, the catalyst particles grow independently without overlap and each nanoparticle is given an independent space, which reduces aggregation and avoids deformation and breakage of particles at high temperatures or under repeated charge and discharge conditions, thereby creating conditions for improving its catalytic performance.
[0013] Charge-discharge experiments on lithium-carbon dioxide batteries show that their cycle charging voltage is below 3.8V and their discharge voltage is around 2.8V; meanwhile, their discharge specific capacity is as high as 12.86mAh / cm³. 2 The charging specific capacity reached 7.27mAh / cm³. 2 The number of cycles reached over 75. Batteries using the above-mentioned lithium-carbon dioxide battery cathode material exhibited excellent performance in terms of overpotential, charge / discharge specific capacity, and cycle performance.
[0014] Preferably, in step (1), the concentration of Sn in the Sn source solution is 0.15–0.35 mol / L, and the impregnation time is 24 hours or more. Vacuum degassing can be assisted during or after impregnation to promote the release of gas from the wood and facilitate solution penetration.
[0015] Preferably, in step (2), the molar ratio of Sn, inorganic base and organic ligand in the Sn source is 0.015-0.035 mol: 2-3 mmol: 1.2-1.6 mmol, and the concentration of the organic ligand in the system is 6-8 mmol / L.
[0016] More preferably, the Sn source is tin sulfate, the inorganic base is sodium hydroxide, and the organic ligand is terephthalic acid.
[0017] Preferably, the reaction temperature in step (2) is 50–60°C and the time is 3–4 h; the carbonization time in step (3) is 2–3 h. More preferably, after solid-liquid separation in step (2), the wood is washed with water and freeze-dried to obtain the Sn-MOF-loaded wood.
[0018] Preferably, the wood matrix in step (1) is balsa wood; the wood matrix is a sheet with a thickness of 1-2 mm. By selecting balsa wood, a material with a naturally three-dimensional structure, the specific surface area of the material is significantly increased, allowing the active sites in the material to be fully exposed to the carbon dioxide atmosphere. After lignin removal, balsa wood has well-developed tubular channels inside, which facilitates the transport of carbon dioxide. Simultaneously, the long tubular channels provide more space for lithium carbonate generated during the discharge of lithium-carbon dioxide batteries, promoting its formation and subsequent decomposition. Overall, balsa wood exhibits better performance compared to other woods.
[0019] Preferably, the removal of lignin in step (1) includes: placing the wood matrix in a mixed solution of sodium hydroxide and sodium sulfite and performing a first high-temperature treatment at 95°C to 98°C, then placing it in a hydrogen peroxide solution and performing a second high-temperature treatment at 95°C to 98°C, then soaking it in water, and then freeze-drying it.
[0020] More preferably, in the mixed solution, the concentration of sodium hydroxide is 2.5–4 mol / L, the concentration of sodium sulfite is 0.4–0.6 mol / L, and the first high-temperature treatment time is 3–4 h; the concentration of hydrogen peroxide solution is 2.5–3.5 mol / L, the second high-temperature treatment time is 2–3 h; and the soaking time is 12 h or more.
[0021] Application of the lithium-carbon dioxide battery cathode material prepared by the above method in lithium-carbon dioxide batteries.
[0022] The lithium-carbon dioxide battery based on the above-mentioned lithium-carbon dioxide battery cathode material exhibits good performance in terms of overpotential, charge-discharge specific capacity, and cycle performance, and the overall performance of the resulting lithium-carbon dioxide battery is good. Attached Figure Description
[0023] Figure 1 This is a surface SEM image of the cathode material prepared in Example 2 of the present invention;
[0024] Figure 2 This is a longitudinal cross-sectional SEM image of the cathode material prepared in Example 2 of the present invention;
[0025] Figure 3 The XRD pattern of the cathode material prepared in Example 2 of this invention;
[0026] Figure 4 The full charge-discharge curves of lithium-carbon dioxide batteries based on cathode materials of different embodiments of the present invention are shown.
[0027] Figure 5The rate performance curve of the lithium-carbon dioxide battery based on the cathode material of Example 2 is shown.
[0028] Figure 6 A comparison chart of the cycle performance of lithium-carbon dioxide batteries based on different cathode materials;
[0029] Figure 7 This is a cycle voltage curve of a lithium-carbon dioxide battery based on the cathode material of Example 2. Detailed Implementation
[0030] The technical concept of this invention is to load Sn-MOF onto the pores of wood and then carbonize it to prepare an electrode material with non-aggregating catalyst particles, stability, and suitability for efficient electrode reactions in lithium-carbon dioxide electrodes. This electrode material belongs to the category of Sn-MOF@C modified three-dimensional self-supporting materials, and battery performance experiments have demonstrated its advantages over battery overpotential, charge-discharge specific capacity, and cycle performance.
[0031] Balsa wood was further selected as the wood substrate because its unique pore structure is suitable for catalyst particle loading and facilitates carbon dioxide transport, providing an excellent reaction site for the generation and decomposition of discharge products.
[0032] By optimizing the carbonization temperature, the catalytic performance of the cathode material can be further improved. Preferably, the heating rate to 650–750°C is 1–3°C / min, which is more suitable and can effectively avoid material deformation caused by excessively rapid heating.
[0033] The implementation process of the present invention will be described in detail below with reference to specific embodiments.
[0034] I. Specific Embodiments of the Preparation Method of the Lithium-Carbon Dioxide Battery Cathode Material of the Present Invention
[0035] Example 1
[0036] The method for preparing the lithium-carbon dioxide battery cathode material in this embodiment includes the following steps:
[0037] 1) Cut balsa wood into 4cm x 4cm square slices, approximately 1-2mm thick. Dissolve 0.5mol of sodium hydroxide solid and 0.08mol of sodium sulfite in 200mL of deionized water to prepare a solution. Completely immerse the wood slices in this solution and incubate at 95℃ for 3 hours. This treatment removes lignin, improving the strength and stability of the wood.
[0038] 2) Remove the wood chips after the water bath and rinse them with deionized water. Prepare 200 ml of a 2.5 mol / L hydrogen peroxide solution and continue immersing the wood chips in it. Then, maintain a constant temperature water bath at 95°C for 2 hours until the wood turns completely white. This step effectively removes pigments and other organic substances from the wood.
[0039] 3) Remove the wood chips treated in step 2) from the solution, wash them repeatedly with deionized water and soak them for 12 hours. After soaking, freeze them at -60℃ for 12 hours, and then dry them in a freeze dryer for 48 hours. This completes the pretreatment of the wood matrix.
[0040] 4) Dissolve 0.015 mol of SnSO4 solid in 100 mL of deionized water and stir for about one hour to obtain solution A. Cut the pretreated wood chips into small, rectangular slices of 1 cm × 1 cm and immerse them in solution A, stirring and soaking for 24 hours. Then, place the wood chips and solution together in a vacuum drying oven and evacuate for 2 hours to completely release the gas inside the wood and allow the solution to fully penetrate.
[0041] 5) After being vacuum-dried in a vacuum drying oven, the concentration of the original solution A changed, so solution A (100 mL, concentration same as in step 4) needs to be prepared again. Take 2.4 mmol of sodium hydroxide and 1.2 mmol of terephthalic acid (C8H6O4) and dissolve them together in 100 mL of deionized water. Stir for one hour to obtain solution B. Mix the wood chips treated in the previous step, solution A and solution B (both solutions A and B are 100 mL in volume) and incubate in a constant temperature water bath at 50°C for 3 hours.
[0042] 6) Remove the wood chips from the water bath after constant temperature water bath, rinse them three times with deionized water, freeze them in a -60℃ refrigerator for 12 hours, and then freeze-dry them in a freeze dryer for 12 hours to produce Sn-MOF modified wood material with a three-dimensional structure.
[0043] 7) The Sn-MOF-modified wood material was heated to 650℃ in an argon atmosphere at a heating rate of 2℃ / min and held for 2h. It was then naturally cooled to room temperature to obtain the cathode material.
[0044] Example 2
[0045] The method for preparing the lithium-carbon dioxide battery cathode material in this embodiment differs from that in Example 1 only in that, in step 7), the Sn-MOF-modified wood material is heated to 700°C at a heating rate of 2°C / min and held for 2 hours in an argon atmosphere.
[0046] Example 3
[0047] The method for preparing the lithium-carbon dioxide battery cathode material in this embodiment differs from that in Example 1 only in that, in step 7), the Sn-MOF-modified wood material is heated to 750°C at a heating rate of 2°C / min and held for 2 hours in an argon atmosphere.
[0048] II. Specific Examples of the Application of Lithium-Carbon Dioxide Battery Cathode Materials in Lithium-Carbon Dioxide Batteries
[0049] Example 4
[0050] The application of the lithium-carbon dioxide battery positive electrode material in this embodiment specifically uses the lithium-carbon dioxide battery positive electrode material from Example 1 as the positive electrode. Because lithium-carbon dioxide batteries readily react with air, assembly must be performed in an air-isolated glove box filled with inert gas. The assembly sequence is: negative electrode battery casing - lithium sheet - glass fiber separator - positive electrode material - positive electrode battery casing. During assembly, a 1 mol / L solution is dropped onto the lithium sheet and the glass fiber separator. -1 A lithium trifluoromethanesulfonylimide (LiTFSI) solution (using tetraethylene glycol dimethyl ether TEGDME as the solvent) was used as the electrolyte. The button batteries were then assembled using a tablet press. After assembly, the batteries were left to stand in a glove box for 10 hours to allow the electrolyte to fully impregnate them.
[0051] Based on this embodiment, lithium-carbon dioxide battery cathode materials from Embodiments 2 and 3 can be used to fabricate corresponding lithium-carbon dioxide batteries.
[0052] III. Experimental Examples
[0053] Experimental Example 1: SEM Analysis
[0054] SEM analysis was performed on the cathode material obtained in Example 2. The surface SEM image and longitudinal cross-sectional SEM image are shown below. Figure 1 , Figure 2 As shown.
[0055] from Figure 1 It can be clearly observed that the nanospheres do not stick together, and the spherical structure remains intact after being subjected to a high temperature of 700℃, with almost no collapse or deformation. Figure 2 In balsa wood, which has been deligated, there are well-developed tubular channels inside, which can effectively transport carbon dioxide. At the same time, the long tubular channels provide more space for lithium carbonate produced during the discharge of lithium-carbon dioxide batteries, which is conducive to its production and subsequent decomposition.
[0056] Experimental Example 2 XRD Analysis
[0057] XRD analysis was performed on the cathode material obtained in Example 2, and the results are as follows: Figure 3 As shown.
[0058] Figure 3 In the figure, black, green, and pink represent the XRD standard cards of Sn-MOF three-dimensional self-supporting carbonized material (i.e., the cathode material of Example 2), Sn, and SnO2, respectively. As can be seen from the figure, 30.644°, 32.018°, 43.871°, 44.902°, 62.538°, and 64.576° correspond to the (200), (101), (220), (211), (112), and (321) crystal planes of Sn, respectively. The (211) crystal plane of SnO2 corresponds to 51.780°. The Sn in Example 2 has a higher crystallinity, and the intensities of these peaks are weaker than those of Sn / SnO2@C, indicating that the crystal particles on this material are smaller. The operation of adsorbing Sn-MOF onto balsa wood effectively reduced particle aggregation.
[0059] Experiment Example 3: Electrical Performance Experiment of Lithium-Carbon Dioxide Battery
[0060] Lithium-carbon dioxide batteries based on the cathode materials of Examples 1-3 were fabricated according to Example 4, and the charge-discharge performance of the lithium-carbon dioxide batteries at different carbonization temperatures was investigated in a CO2 atmosphere.
[0061] Figure 4 The charge / discharge tests were conducted at a fixed current density of 0.05 mA / cm². 2 .Depend on Figure 4 It can be seen that the cathode material prepared by high-temperature carbonization at 700℃ exhibits the best catalytic performance, enabling the lithium-carbon dioxide battery to achieve a discharge specific capacity as high as 12.86 mAh / cm³. 2 The charging specific capacity reached 7.27mAh / cm³. 2 .
[0062] Figure 5 The charge / discharge specific capacity performance at different current densities is shown. Increasing the current density leads to a decrease in charge / discharge specific capacity; at a current density of 0.1 mA / g, the discharge specific capacity is approximately 5 mAh / cm³. 2 When the discharge current density increases to 0.2 mA / cm 2 At that time, the discharge specific capacity further decreased to 3.58 mAh / cm³. 2 .
[0063] Figure 6 The results are from the lithium-carbon dioxide battery cycle performance test based on the cathode material of Example 2. The current density during the cycle performance test was 0.05 mAh / cm². 2 The specific capacity is limited to 0.15 mAh / cm³. 2Compared to using the pretreated wood matrix in step 3) as the positive electrode, the lithium-carbon dioxide battery based on the positive electrode material of Example 2 exhibits significantly improved cycle stability. The number of cycles is increased to over 75, and during cycling, the charging voltage can be reduced to below 3.8V, while the discharging voltage remains consistently around 2.8V.
[0064] The charge and discharge plateaus are crucial indicators for evaluating the performance of lithium-carbon dioxide batteries. An ideal battery should possess a broad and stable charge and discharge plateau to achieve higher energy density and better cycle life. The charge plateau refers to the region during charging where the voltage of a lithium-carbon dioxide battery reaches a certain value and remains relatively stable. The discharge plateau refers to the region during discharging where the voltage of a lithium-carbon dioxide battery remains at a relatively stable level. Figure 7 The cycle voltage curve of the lithium-carbon dioxide battery based on the cathode material of Example 2 is further shown. From Figure 7 As can be seen, the charging curves of this lithium-carbon dioxide battery exhibit high overlap, with only a small change in the charging plateau from cycle 20 to cycle 75, amounting to only 0.05V. The discharge plateau gradually decreases, but even up to the 75th cycle, the discharge voltage plateau still reaches 2.73V. This significant decrease in the charging plateau demonstrates the catalytic characteristics of the fully dispersed carbonized nanoparticles and the three-dimensional self-supporting cathode material of this embodiment, which is beneficial for improving cycle performance and increasing the cycle stability of the battery.
Claims
1. A method for preparing a lithium-carbon dioxide battery cathode material, characterized in that, Includes the following steps: (1) The wood matrix after lignin removal is immersed in Sn source solution to obtain a wood matrix with Sn adsorbed. (2) The wood matrix with Sn adsorbed is reacted with Sn source, inorganic base and organic ligand, and solid-liquid separation is performed to obtain Sn-MOF loaded wood. (3) The Sn-MOF-loaded wood is carbonized at 650-750°C under a protective atmosphere.
2. The method for preparing the lithium-carbon dioxide battery cathode material as described in claim 1, characterized in that, In step (1), the concentration of Sn in the Sn source solution is 0.15 to 0.35 mol / L, and the immersion time is more than 24 hours.
3. The method for preparing the lithium-carbon dioxide battery cathode material as described in claim 1, characterized in that, In step (2), the molar ratio of Sn, inorganic base and organic ligand in Sn source is 0.015-0.035 mol: 2-3 mmol: 1.2-1.6 mmol, and the concentration of organic ligand in system is 6-8 mmol / L.
4. The method for preparing the lithium-carbon dioxide battery cathode material as described in claim 3, characterized in that, The Sn source is tin sulfate, the inorganic base is sodium hydroxide, and the organic ligand is terephthalic acid.
5. The method for preparing the lithium-carbon dioxide battery cathode material according to any one of claims 1 to 4, characterized in that, The reaction temperature in step (2) is 50-60℃ and the time is 3-4h; the carbonization time in step (3) is 2-3h.
6. The method for preparing the lithium-carbon dioxide battery cathode material as described in claim 5, characterized in that, After solid-liquid separation in step (2), the wood is washed with water and freeze-dried to obtain the Sn-MOF-loaded wood.
7. The method for preparing the lithium-carbon dioxide battery cathode material as described in claim 1, characterized in that, The wood matrix in step (1) is balsa wood; the wood matrix is a sheet with a thickness of 1-2 mm.
8. The method for preparing the lithium-carbon dioxide battery cathode material as described in claim 1 or 7, characterized in that, Step (1) involves removing lignin by placing the wood matrix in a mixed solution of sodium hydroxide and sodium sulfite and performing a first high-temperature treatment at 95°C to 98°C, then placing it in a hydrogen peroxide solution and performing a second high-temperature treatment at 95°C to 98°C, then soaking it in water, and finally freeze-drying it.
9. The method for preparing the lithium-carbon dioxide battery cathode material as described in claim 8, characterized in that, In the mixed solution, the concentration of sodium hydroxide is 2.5–4 mol / L, the concentration of sodium sulfite is 0.4–0.6 mol / L, and the first high-temperature treatment time is 3–4 h; the concentration of hydrogen peroxide solution is 2.5–3.5 mol / L, the second high-temperature treatment time is 2–3 h; and the soaking time is more than 12 h.
10. The application of a lithium-carbon dioxide battery cathode material prepared by any one of claims 1 to 9 in a lithium-carbon dioxide battery.