Lithium-carbon dioxide battery positive electrode catalyst, preparation method and lithium-carbon dioxide battery

Abstract

The invention belongs to the technical field of lithium-carbon dioxide batteries, and particularly relates to a lithium-carbon dioxide battery positive electrode catalyst, a preparation method and a lithium-carbon dioxide battery. Comprising the following steps: taking iron, cobalt, nickel and copper as templates, respectively grinding and mixing with 1, 2, 4, 5,-tetracyanobenzene, sintering under a vacuum condition, respectively coordinating the 1, 2, 4, 5,-tetracyanobenzene with metal ions to form polymer monomers, and polymerizing the polymer monomers to form iron polyphthalocyanine, thereby obtaining the lithium-carbon dioxide battery positive electrode catalyst. The iron polyphthalocyanine is adopted as the positive electrode catalyst of the lithium-carbon dioxide battery, so that the generation of lithium oxalate is realized, the discharge voltage is improved to be higher than a theoretical value 3.01 V, the charging voltage is reduced, and the energy efficiency of the battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-carbon dioxide battery technology, specifically relating to a positive electrode catalyst for lithium-carbon dioxide batteries, its preparation method, and lithium-carbon dioxide batteries. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) of carbon dioxide is crucial for addressing the global challenge of climate change. Among various CCUS technologies, lithium-carbon dioxide batteries have attracted attention from various industries because they can convert the greenhouse gas carbon dioxide into value-added chemicals (carbonates, oxalates, etc.) and generate electricity. This device has a high theoretical discharge voltage (Ei). 0 =2.8V) and high energy density (E=1876Wh·kg) -1 Therefore, it has potential applications in electric vehicles, flexible wearable devices, deep-sea exploration, and future Mars migration. However, reported lithium-carbon dioxide batteries typically only provide a discharge voltage of 2.0V to 2.5V. This is mainly due to the high carbon dioxide content (+805kJ·mol⁻¹). -1 The lithium-carbon dioxide battery exhibits strong chemical bonds and poor electronic and ionic conductivity in both the bulk phase and the three-phase interface (gas-electrolyte-cathode). Furthermore, the cathode surface is typically covered by insulating discharge products, Li₂CO₃, which not only slows down subsequent reactions but also results in charging voltages exceeding 4.0V, leading to relatively low energy efficiency. Therefore, there is an urgent need to reduce the charging voltage of lithium-carbon dioxide batteries.

[0003] The main strategy in existing technologies is to improve the discharge voltage and reduce the charging voltage of lithium-carbon dioxide batteries by designing catalysts to promote the formation and decomposition of lithium carbonate. Various heterogeneous or homogeneous catalysts, such as oxides, metal complexes, organic molecules, and halides, are used to increase the discharge voltage and decrease the charging voltage of lithium-carbon dioxide batteries. These emerging catalysts gradually bring the discharge voltage closer to the theoretical discharge voltage and reduce the charging voltage by promoting the formation and decomposition of lithium carbonate. However, due to the thermodynamic properties of lithium carbonate itself, the increase in discharge voltage and the decrease in charging voltage of lithium-carbon dioxide batteries are not significant. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a lithium-carbon dioxide battery cathode catalyst, its preparation method, and a lithium-carbon dioxide battery. By using iron polyphthalocyanine as the cathode catalyst, a lithium-carbon dioxide battery via the oxalate pathway is achieved, resulting in a discharge voltage higher than the theoretical value.

[0005] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0006] The first objective of this invention is to provide a method for preparing a cathode catalyst for lithium-carbon dioxide batteries, comprising the following steps: Using iron, cobalt, nickel, and copper as templates, they were ground and mixed with 1,2,4,5,-tetracyanobenzene, and sintered under vacuum conditions. This allowed the 1,2,4,5,-tetracyanobenzene to coordinate with metal ions to form polymer monomers. The polymer monomers were then polymerized to form iron polyphthalocyanine, thus obtaining a lithium-carbon dioxide battery cathode catalyst.

[0007] Furthermore, the molar ratio of 1,2,4,5,-tetracyanobenzene to iron is 40:24 to 40; the molar ratio of 1,2,4,5,-tetracyanobenzene to cobalt is 40:20 to 40; the molar ratio of 1,2,4,5,-tetracyanobenzene to nickel is 40:45 to 90; and the molar ratio of 1,2,4,5,-tetracyanobenzene to copper is 40:250 to 400.

[0008] Furthermore, nickel is replaced by anhydrous nickel chloride, and copper ions are replaced by anhydrous copper chloride. The sintering temperature is 300℃~500℃, the holding time is 3h~6h, and the heating rate is 2℃ / min~10℃ / min.

[0009] Furthermore, after sintering, the sample is washed 3 to 5 times with ethanol, ferric chloride solution and water in sequence, and then vacuum dried at 40℃ to 70℃ for 10 to 14 hours.

[0010] The second objective of this invention is to provide a lithium-carbon dioxide battery cathode catalyst, which is prepared using the above-described preparation method.

[0011] The third objective of this invention is a lithium-carbon dioxide battery, which includes a porous cathode, an anode, a separator, and an electrolyte. The cathode and anode are arranged opposite each other through the separator. The porous cathode is formed by mixing Super P, the above-mentioned iron polyphthalocyanine and PVDF to form an active material. The active material is dissolved in a solvent to form a slurry, and the slurry is coated on carbon paper to obtain the battery.

[0012] Furthermore, the weight ratio of Super P, lithium-carbon dioxide battery cathode catalyst, and PVDF is 1–2:7–8:1.

[0013] Furthermore, the loading of active material on the carbon paper is 0.1 mg / cm³. 2 ~0.3mg / cm 2 .

[0014] Furthermore, the electrolyte is 1.0 M LiTFSI / TEGDME, the concentration of LiTFSI in TEGDME is 1 mol / L to 3 mol / L, and the anode is metallic lithium.

[0015] Compared with the prior art, the present invention has the following advantages: The present invention provides a method for preparing a lithium-carbon dioxide battery cathode catalyst. Different metals are mixed with 1,2,4,5,-tetracyanobenzene, and the mixture is ground to allow the nitrogen atoms on the 1,2,4,5,-tetracyanobenzene to undergo initial coordination with metal ions of iron, cobalt, nickel, and copper, respectively. This promotes the distance between reactants and activates the cyano functional groups. During sintering, the 1,2,4,5,-tetracyanobenzene coordinates with metal ions to form polymer monomers. The 1,2,4,5,-tetracyanobenzene acts as a "bridge" between the polymer monomers, polymerizing to form an iron-based polyphthalocyanine structure, thus obtaining an iron-based polyphthalocyanine network polymer, which is the lithium-carbon dioxide battery cathode catalyst. Iron-based polyphthalocyanine has a strong electron-accepting ability; after gaining electrons, it transfers them to CO2. The CO2 is then reduced and combines with Li... + Lithium oxalate is generated. The electron potential of polyferric phthalocyanine itself is 3.2V, so polyferric phthalocyanine has a high discharge platform in Li-CO2 batteries. By using polyferric phthalocyanine as a positive electrode catalyst, lithium-carbon dioxide batteries via the oxalate pathway are realized, and the discharge voltage is higher than the theoretical value. Attached Figure Description

[0016] Figure 1 This is the molecular structural formula of the lithium-carbon dioxide battery cathode catalyst of the present invention. Figure 1 In this diagram, 'a' represents a polymer monomer, and 'b' represents an iron-based polyphthalocyanine structure.

[0017] Figure 2 This is a diagram showing the limited charge and discharge capacity of the lithium-carbon dioxide battery electrode of the present invention.

[0018] Figure 3 This is a diagram showing the extreme long-cycle characteristics of the lithium-carbon dioxide battery electrode of this invention.

[0019] Figure 4 This is a diagram showing the rate performance of the lithium-carbon dioxide battery electrode of the present invention.

[0020] Figure 5 This is a graph showing the ultrawide temperature range performance of the lithium-carbon dioxide battery of this invention.

[0021] Figure 6 This is an in-situ Raman image of the discharge products of the lithium-carbon dioxide battery of the present invention.

[0022] Figure 7 This is an in-situ XRD pattern of the discharge products of the lithium-carbon dioxide battery of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0025] Lithium-carbon dioxide batteries have a high theoretical discharge voltage (2.8V) and energy density (1876Wh·kg⁻¹). -1 However, lithium carbonate, the insulating product generated during the discharge process, has extremely poor conductivity. The decomposition of these discharge products during charging requires a voltage higher than 4V, resulting in relatively low energy efficiency in lithium-carbon dioxide batteries. Current technologies primarily employ catalysts to promote the formation and decomposition of lithium carbonate, thereby increasing the discharge voltage and decreasing the charging voltage. However, due to the inherent thermodynamic properties of lithium carbonate, the increase in discharge voltage and the decrease in charging voltage of lithium-carbon dioxide batteries are not significant.

[0026] Based on this, the present invention provides a method for preparing a cathode catalyst for lithium-carbon dioxide batteries, comprising the following steps: Using iron, cobalt, nickel, and copper as templates, they were ground and mixed with 1,2,4,5,-tetracyanobenzene, and then sintered under vacuum conditions. This allowed the 1,2,4,5,-tetracyanobenzene to coordinate with metal ions to form polymer monomers. The polymer monomers then polymerized to form iron polyphthalocyanine. After sintering, a lithium-carbon dioxide battery cathode catalyst was obtained.

[0027] More specifically, 1,2,4,5,-tetracyanobenzene is mixed with iron, cobalt, anhydrous nickel chloride, and anhydrous copper chloride to form a mixture. After grinding, the mixture is sintered under vacuum at a temperature of 2℃ / min to 10℃ / min to 300℃ to 500℃ for 3h to 6h. After sintering, the mixture is washed 3 to 5 times with ethanol, ferric chloride solution, and water in sequence, and then vacuum dried at 40℃ to 70℃ for 10h to 14h to obtain iron polyphthalocyanine, which is the positive electrode catalyst for lithium-carbon dioxide batteries.

[0028] The molar ratio of 1,2,4,5,-tetracyanobenzene to iron is 40:24–40; the molar ratio of 1,2,4,5,-tetracyanobenzene to cobalt is 40:20–40; the molar ratio of nickel in 1,2,4,5,-tetracyanobenzene and anhydrous nickel chloride is 40:45–90; and the molar ratio of copper in 1,2,4,5,-tetracyanobenzene and anhydrous copper chloride is 40:250–400.

[0029] In this invention, different metals are mixed with 1,2,4,5,-tetracyanobenzene, and then ground to allow the nitrogen atoms on the 1,2,4,5,-tetracyanobenzene to undergo preliminary coordination with metal ions of iron, cobalt, nickel, and copper, respectively, thereby increasing the distance between the reactants and activating the cyano functional group; for example... Figure 1 As shown, during the sintering process, 1,2,4,5,-tetracyanobenzene coordinates with metal ions to form polymer monomers such as... Figure 1 As shown in Figure a, 1,2,4,5,-tetracyanobenzene acts as a "bridge" between the polymer monomers, and polymerization forms an iron-based polyphthalocyanine structure as shown in Figure a. Figure 1 As shown in Figure b, an iron-based polyphthalocyanine network polymer is obtained, which is the positive electrode catalyst for lithium-carbon dioxide batteries.

[0030] In some embodiments, the sintering temperature is 300℃~500℃, the holding time is 3h~6h, and the heating rate is 2℃ / min~10℃ / min. As a preferred embodiment of the present invention, the sintering temperature is 400℃, the holding time is 4h, and the heating rate is 5℃ / min.

[0031] This invention also provides a lithium-carbon dioxide battery cathode catalyst. The lithium-carbon dioxide battery cathode catalyst is used to prepare a lithium-carbon dioxide battery, which includes a porous cathode, an anode, a separator, and an electrolyte. The cathode and anode are arranged opposite each other via the separator. The porous cathode is formed by mixing Super P, the aforementioned iron polyphthalocyanine, and PVDF in a weight ratio of 1–2:7–8:1 to form an active material. The active material is then dissolved in a suitable NMP solvent to form a slurry. Subsequently, the slurry is coated onto carbon paper, ensuring an active material loading of 0.1 mg / cm³ on the carbon paper. 2 ~0.3mg / cm 2 A porous cathode is obtained.

[0032] Under inert gas protection, a porous cathode, a glass fiber membrane, a lithium metal anode, and 100 μL of 1.0 M LiTFSI / TEGDME electrolyte were assembled, wherein the concentration of LiTFSI in TEGDME was 1 mol / L to 3 mol / L, to obtain a lithium-carbon dioxide battery.

[0033] In this invention, ferrocyanine has a strong electron-accepting ability. After gaining electrons, it transfers them to CO2. After CO2 is reduced, it combines with Li. + Lithium oxalate is generated. The electron potential of poly(ferric phthalocyanine) itself is 3.2V, so poly(ferric phthalocyanine) has a high discharge platform when used in Li-CO2 batteries.

[0034] The following specific examples will provide further explanation.

[0035] Example 1 A method for preparing a lithium-carbon dioxide battery cathode catalyst includes the following steps: 50 mmol of 1,2,4,5,-tetracyanobenzene was mixed with 31.5 mmol of iron powder, 33 mmol of cobalt powder, 72.5 mmol of anhydrous nickel chloride, and 387 mmol of anhydrous copper chloride, respectively, to form four mixtures. These four mixtures were then combined, ground, and transferred to a heat-resistant glass tube. The heat-resistant glass tube was then evacuated and flame-sealed. The glass tube was heated to 400°C at a rate of 5°C / min and held at this temperature for 4 hours under vacuum in a tube furnace. After cooling to room temperature, the mixture was washed three times with ethanol, ferric chloride solution, and water, and then dried in a vacuum oven at 60°C for 12 hours to obtain a purplish-black powder, which is iron polyphthalocyanine, the positive electrode catalyst for lithium-carbon dioxide batteries.

[0036] Example 2 A method for preparing a lithium-carbon dioxide battery cathode catalyst includes the following steps: 40 mmol of 1,2,4,5,-tetracyanobenzene was mixed with 30 mmol of iron powder, 30 mmol of cobalt powder, 70 mmol of anhydrous nickel chloride, and 254 mmol of anhydrous copper chloride, respectively, to form four mixtures. These four mixtures were then combined, ground, and transferred to a heat-resistant glass tube. The heat-resistant glass tube was then evacuated and flame-sealed. The glass tube was heated to 400°C at a rate of 5°C / min and held at this temperature for 3 hours under vacuum in a tube furnace. After cooling to room temperature, the mixture was washed three times with ethanol, ferric chloride solution, and water, and then dried in a vacuum oven at 60°C for 12 hours to obtain a purplish-black powder, which is iron polyphthalocyanine, the positive electrode catalyst for lithium-carbon dioxide batteries.

[0037] Example 3 A method for preparing a lithium-carbon dioxide battery cathode catalyst includes the following steps: 60 mmol of 1,2,4,5,-tetracyanobenzene was mixed with 50 mmol of iron powder, 50 mmol of cobalt powder, 90 mmol of anhydrous nickel chloride, and 400 mmol of anhydrous copper chloride, respectively, to form four mixtures. These four mixtures were then combined, ground, and transferred to a heat-resistant glass tube. The heat-resistant glass tube was then evacuated and flame-sealed. The glass tube was heated to 400°C at a rate of 5°C / min and held at this temperature for 4 hours under vacuum in a tube furnace. After cooling to room temperature, the mixture was washed three times with ethanol, ferric chloride solution, and water, and then dried in a vacuum oven at 60°C for 12 hours to obtain a purplish-black powder, which is iron polyphthalocyanine, the positive electrode catalyst for lithium-carbon dioxide batteries.

[0038] Since the lithium-carbon dioxide battery cathode catalysts prepared in Examples 1 to 3 have the same structure and basically similar performance, the structure of the prepared lithium-carbon dioxide battery cathode catalyst was tested using the lithium-carbon dioxide battery cathode catalyst prepared in Example 1 as an example. The results are as follows:

[0039] The lithium-carbon dioxide battery cathode catalyst prepared in Example 1 was used in a lithium-carbon dioxide battery. The lithium-carbon dioxide battery includes a porous cathode, an anode, a separator, and an electrolyte. The cathode and anode are arranged opposite each other via the separator. The porous cathode is formed by grinding and mixing Super P, the lithium-carbon dioxide battery cathode catalyst prepared in Example 1, and PVDF in a weight ratio of 1:8:1 to form an active material. The active material is then dissolved in 1 mL of N-methylpyrrolidone (NMP) solvent to form a slurry. Subsequently, the slurry is coated onto carbon paper, ensuring an active material loading of 0.1 mg / cm³ on the carbon paper. 2 A porous cathode is obtained.

[0040] The active material was prepared by grinding and mixing Super P and PVDF at a weight ratio of 9:1. The active material was then dissolved in 1 mL of N-methylpyrrolidone (NMP) solvent to form a slurry. Subsequently, the slurry was coated onto carbon paper, ensuring an active material loading of 0.1 mg / cm³ on the carbon cloth. 2 , as a control sample.

[0041] Under argon inert gas protection, a porous cathode, a glass fiber membrane, a lithium metal anode, and 100 μL of 1.0 M LiTFSI / TEGDME electrolyte were assembled to obtain a CR2032 button cell with carbon dioxide permeation pores, which is a lithium-carbon dioxide battery. The assembled lithium-carbon dioxide battery was placed in a sealed glass bottle containing carbon dioxide and allowed to stand for 8 hours before being tested at different temperatures using a blue electrode tester.

[0042] Figure 2 This is a diagram showing the limited charge / discharge capacity of the lithium-carbon dioxide battery electrode of the present invention. (See diagram below.) Figure 2 As shown, the oxalate pathway lithium-carbon dioxide battery has a maximum discharge capacity of 28790 mAh / g and a charging capacity of 21698 mAh / g, while the control group has a discharge capacity of 11482 mAh / g and a charging capacity of 9333 mAh / g.

[0043] Figure 3 This is a diagram showing the extreme long-cycle performance of the lithium-carbon dioxide battery electrode of this invention. (See diagram for reference.) Figure 3 As shown, the cycle test conditions are as follows: cutoff capacity is 1000mAh / g and current density is 100mA / g. The results show that the lithium-carbon dioxide battery using iron polyphthalocyanine as the positive electrode catalyst can cycle stably for more than 1400 hours, of which the cycle discharge voltage is higher than 3.01V after 800 hours.

[0044] Figure 4 This is a rate performance diagram of the lithium-carbon dioxide battery electrode of the present invention. (See diagram below.) Figure 4 As shown, the rate performance of lithium-carbon dioxide batteries at different current densities was tested when the cutoff capacity was 1000 mAh / g. The results showed that iron polyphthalocyanine as a positive electrode catalyst has good catalytic kinetics.

[0045] Figure 5 This is a graph showing the ultra-wide temperature range performance of the lithium-carbon dioxide battery of this invention. (See figure.) Figure 5 As shown, the electrochemical performance of the lithium-carbon dioxide battery was tested at -40℃, -30℃, -20℃, 0℃, 20℃, 40℃, 60℃ and 80℃ when the cutoff capacity was 500mAh / g. The results showed that the battery has excellent stability.

[0046] Figure 6 This is an in-situ Raman image of the discharge products of the lithium-carbon dioxide battery of the present invention. Figure 7 This is an in-situ XRD pattern of the discharge products of the lithium-carbon dioxide battery of the present invention. Figure 7 The curves in the image, from top to bottom, represent the original electrode, the electrode after being left to stand in CO2, the electrode after discharge, and the electrode after charging. For example... Figure 6 and Figure 7 As shown, the discharge products are lithium oxalate, and the generation and reversible decomposition of the discharge products are demonstrated.

[0047] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0048] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a lithium-carbon dioxide battery cathode catalyst, characterized by, Comprising the following steps: Iron, cobalt, nickel and copper as a template, respectively, with 1,2,4,5, -tetra cyanobenzene grinding mixed, sintering under vacuum conditions, so that 1,2,4,5, -tetra cyanobenzene and metal ions are respectively coordinated to form a polymer monomer, the polymer monomer is polymerized to form iron polyphthalocyanine, and a lithium-carbon dioxide battery positive electrode catalyst is obtained.

2. The method for preparing the lithium-carbon dioxide battery cathode catalyst according to claim 1, characterized in that, The molar ratio of 1,2,4,5, -tetra cyanobenzene to iron is 40:24-40; the molar ratio of 1,2,4,5, -tetra cyanobenzene to cobalt is 40:20-40; the molar ratio of 1,2,4,5, -tetra cyanobenzene to nickel is 40:45-90; and the molar ratio of 1,2,4,5, -tetra cyanobenzene to copper is 40:250-400.

3. The method for preparing the lithium-carbon dioxide battery cathode catalyst according to claim 1, characterized in that, Nickel is replaced by anhydrous nickel chloride, copper ions are replaced by anhydrous copper chloride, the sintering temperature is 300-500℃, the holding time is 3-6h, and the heating rate is 2-10℃ / min.

4. The method for preparing the lithium-carbon dioxide battery cathode catalyst according to claim 1, characterized in that, After sintering, the sample is washed with ethanol, iron chloride solution and water for 3-5 times, and vacuum dried at 40-70℃ for 10-14h.

5. A lithium-carbon dioxide battery cathode catalyst, characterized by, The lithium-carbon dioxide battery positive electrode catalyst is prepared by the preparation method of any one of claims 1-4.

6. A lithium-carbon dioxide battery, characterized by, The lithium-carbon dioxide battery comprises a porous cathode, an anode, a separator and an electrolyte, and the cathode and the anode are oppositely arranged through the separator, wherein the porous cathode is formed by mixing Super P, the lithium-carbon dioxide battery positive electrode catalyst of claim 5 and PVDF to form an active material, the active material is dissolved in a solvent to form a slurry, and the slurry is coated on carbon paper to obtain the lithium-carbon dioxide battery positive electrode catalyst.

7. The lithium-carbon dioxide battery of claim 6, wherein, The weight ratio of Super P, the lithium-carbon dioxide battery positive electrode catalyst and PVDF is 1-2:7-8:

1.

8. The lithium-carbon dioxide battery of claim 6, wherein, The loading of active material on the carbon paper was 0.1 mg / cm 2 ~ 0.3 mg / cm 2 .

9. The lithium-carbon dioxide battery of claim 6, wherein, The electrolyte is 1.0 M LiTFSI / TEGDME, the concentration of LiTFSI in TEGDME is 1-3mol / L, and the anode is metal lithium.

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