Transition metal oxalate interlayer hydrogen bond regulation and control strategy and application thereof

Abstract

The invention discloses a transition metal oxalate interlayer hydrogen bond regulation and control strategy and application thereof.The transition metal oxalate interlayer hydrogen bond regulation and control strategy is characterized in that a high-density hydrogen bond is formed by means of a polyhydric alcohol intersoluble polyhydroxy group (-OH) and transition metal oxalate interlayer metal atoms, stable interlayer hydrogen bonds are constructed by means of the acting force between alcohol molecules, the interlayer distance is enlarged, and a porous structure is formed; and the lithium ion transmission efficiency and the material structure stability are obviously enhanced. According to the preparation method disclosed by the invention, the inherent defects of high hydrogen bond strength, high dehydration difficulty, serious lattice defects, poor interlayer stability and the like of traditional water molecules constructed between transition metal oxalate layers are overcome from a dual strategy of micro-nano structure-interlayer bonding regulation of the material; and the transition metal oxalate material which is stable and is easy to remove interlayer hydrogen bonds is constructed. In addition, the transition metal oxalate can be used as a lithium ion battery negative electrode material, and development of a high-energy and long-cycle-life lithium ion battery is realized.

Description

Technical Field

[0001] The present invention relates to a transition metal oxalate interlayer hydrogen bond regulation strategy and application thereof, and belongs to the technical field of lithium ion batteries. Background Art

[0002] As the core energy storage device in the current new energy field, lithium-ion batteries continue to see growing demand for applications in electric vehicles, energy storage grids, and other fields. Among them, the performance improvement of negative electrode materials, as key components that determine the energy density and cycle life of batteries, has always been a research hotspot. Transition metal oxalate materials are regarded as one of the most promising next-generation negative electrode materials due to their advantages such as high theoretical specific capacity, low cost, and environmental friendliness. However, in practical applications, transition metal oxalate materials still face many challenges: 1. The ion migration rate of the material itself is low, and the migration path of lithium ions between layers is limited, resulting in insufficient electrochemical activity; 2. Although the presence of interlayer crystalline water can provide certain structural support, it is easy to cause lattice distortion, and the interlayer structure collapses after dehydration, resulting in severe capacity attenuation during the cycle and unable to meet the application requirements of high power and long life.

[0003] In response to the above problems, material micro-nanostructure regulation and crystal structure construction are effective means to improve the structural stability of transition metal oxalate materials and enhance ion migration. Among them, regulating the interlayer spacing of transition metal oxalate can significantly improve its ion migration ability. Due to the strong interlayer ionic bonds and hydrogen bonds, crystal water can provide a stable maintenance force and expand the interlayer spacing, while the interlayer water groups can serve as pillars to fix the layers together, maintain substantial structural stability and form excellent long-term stability. The directionality and stability of hydrogen bonds directly affect the interlayer spacing, ion transport channels and mechanical strength of the material. The traditional means of regulating interlayer hydrogen bonds and crystal water is through direct calcination. This process has problems such as uneven interlayer hydrogen bond construction, uncontrollable amount of crystal water, obvious local side reactions, and cannot achieve precise construction of interlayer crystal structure. Summary of the Invention

[0004] The present invention addresses the problems of low electronic conductivity, poor interlayer structural stability, and significant cycle capacity decay in existing transition metal oxalate negative electrode materials. The present invention provides a method for regulating the interlayer hydrogen bond construction form through alcohol solvents to achieve simultaneous improvement in the micro-nanostructure and electrochemical performance of ferrous oxalate composite materials. The present invention starts with the interlayer hydrogen bond construction method and utilizes the intermolecular forces of alcohol to construct stable interlayer hydrogen bonds. This overcomes the inherent defects of traditional water molecules in transition metal oxalate interlayers, such as high hydrogen bond strength, difficulty in dehydration, severe lattice defects, and poor interlayer stability. It effectively expands the interlayer spacing and constructs a porous structure, thereby improving lithium ion diffusion kinetics and structural stability.

[0005] A strategy for regulating hydrogen bonds between transition metal oxalate layers, the specific steps of which are as follows:

[0006] (1) Weighing dihydrate oxalic acid and aqueous sulfate, respectively, and sintering and dehydrating them in an inert atmosphere, wherein the sintering temperatures are 80°C to 150°C and 300°C to 450°C, respectively, with a heating rate of 1-5°C / min and a holding time of 2-6 hours to obtain anhydrous oxalic acid and anhydrous ferrous sulfate;

[0007] (2) Weighing the anhydrous sulfate obtained in step (1) and adding it to deionized water or alcohol or a deionized water-alcohol mixed solution with ascorbic acid, and electromagnetically stirring for 1-3 hours to obtain a sulfate solution; weighing the anhydrous oxalic acid obtained in step (1) and adding it to the alcohol solution, and electromagnetically stirring for 1-3 hours to obtain an oxalic acid solution, wherein the volume ratio of deionized water to alcohol is 1:10 to 3:10, the mass ratio of ascorbic acid to anhydrous sulfate is 1:8 to 1:12, the molar ratio of anhydrous oxalic acid to anhydrous sulfate is 1:1 to 5:1, the mass concentration of the sulfate solution is 3% to 30%, and the mass concentration of the oxalic acid solution is 3% to 50%;

[0008] (3) Slowly adding the oxalic acid solution in step (2) to the sulfate solution, electromagnetically stirring for 10-60 minutes, and then transferring to a high-temperature and high-pressure hydrothermal reactor, the reaction temperature is 50°C to 120°C, the reaction time is 8 to 24 hours, after the reaction is completed, filtering, washing, and vacuum drying to obtain a transition metal oxalate precursor after interlayer hydrogen bond regulation;

[0009] (4) Under an argon or nitrogen inert atmosphere, the transition metal oxalate precursor with interlayer hydrogen bonds obtained in step (3) is sintered at 150° C. to 280° C. for 1 to 6 hours to obtain a transition metal oxalate material regulated by interlayer hydrogen bonds.

[0010] Another object of the present invention is to use the prepared hydrogen bond-regulated transition metal oxalate as a negative electrode material for lithium-ion batteries.

[0011] The beneficial effects of the present invention are:

[0012] The present invention forms high-density hydrogen bonds with metal atoms between the interlayers of transition metal oxalate by means of polyol-soluble polyhydroxyl groups (-OH), thereby preparing a transition metal oxalate material after the interlayer hydrogen bond regulation. Its high-density hydrogen bonds construct a stable interlayer hydrogen bond network, effectively expand the interlayer spacing and induce the formation of a porous layered structure, significantly enhancing the lithium ion transmission efficiency. At the same time, the hydrogen bond network induced by the alcohol solvent is used to form hydrogen bonds with part of the crystal water to inhibit the structural collapse during the dehydration process, enhance the interlayer bonding force and cyclic structural stability of the material, overcome the inherent defects of the traditional water molecules in the interlayer of transition metal oxalate, such as high hydrogen bond strength, great dehydration difficulty, serious lattice defects, and poor interlayer stability, significantly improving the electrochemical properties of the material such as electrochemical activity and cyclic stability, and promoting the application of transition metal oxalates in high-performance lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 X-ray diffraction patterns of the interlayer hydrogen bond-regulated oxalate composite materials prepared in Examples 1, 2, and 3 of the present invention;

[0014] Figure 2 Scanning electron micrographs of the interlayer hydrogen bond-regulated oxalate composite materials prepared in Examples 1, 2, and 3 of the present invention;

[0015] Figure 3 TG and DTG curves of ferrous oxalate synthesized in Example 1 of the present invention;

[0016] Figure 4 TG and DTG curves of ferrous oxalate synthesized in Example 2 of the present invention;

[0017] Figure 5 TG and DTG curves of ferrous oxalate synthesized in Example 3 of the present invention;

[0018] Figure 6 This is a cycling curve diagram of the interlayer hydrogen bond-regulated oxalate composite material prepared in Examples 1, 2, and 3 of the present invention at 3C;

[0019] Figure 7 This is a diagram of the capacity retention rate of the interlayer hydrogen bond-regulated oxalate composite material prepared in Examples 1, 2, and 3 of the present invention at 3C. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0021] Example 1: In this example, a transition metal oxalate interlayer hydrogen bond regulation strategy is as follows:

[0022] (1) Weighing dihydrate oxalic acid and hydrous ferrous sulfate, respectively, and sintering and dehydrating them in an inert atmosphere at temperatures of 125°C and 350°C, respectively, with a heating rate of 5°C / min, and both temperatures are kept for 3 hours to obtain anhydrous oxalic acid and anhydrous ferrous sulfate;

[0023] (2) Weighing the anhydrous ferrous sulfate and ascorbic acid obtained in step (1), adding them to deionized water, and electromagnetically stirring for 2 hours to obtain a ferrous sulfate solution; weighing the anhydrous oxalic acid obtained in step (1), adding it to an ethanol solution, and electromagnetically stirring for 2 hours to obtain an oxalic acid solution, wherein the mass ratio of ascorbic acid to anhydrous ferrous sulfate is 1:11, the molar ratio of anhydrous oxalic acid to anhydrous ferrous sulfate is 1:1, the mass concentration of the ferrous sulfate solution is 3.6%, and the mass concentration of the oxalic acid solution is 5.8%;

[0024] (3) Slowly adding the oxalic acid solution in step (2) to the ferrous sulfate solution, electromagnetically stirring for 30 minutes, and then transferring to a high-temperature and high-pressure hydrothermal reactor, the reaction temperature is 60°C, the reaction time is 12 hours, and after the reaction is completed, filtering, washing, and vacuum drying to obtain a transition metal oxalate precursor after interlayer hydrogen bond regulation;

[0025] (4) Under an argon or nitrogen inert atmosphere, the transition metal oxalate precursor with interlayer hydrogen bonds obtained in step (3) is sintered at 250° C. for 3 h to obtain a transition metal oxalate material regulated by interlayer hydrogen bonds.

[0026] After accurately weighing 0.02g of polyvinylidene fluoride (PVDF) powder, place it in a glass vial equipped with a rotor. Add 0.75ml of N-methyl-2-pyrrolidone (NMP) solution to the vial and stir it on a magnetic stirrer for 1 hour to allow the PVDF to fully dissolve. After stirring, add 0.06g of carbon black to the vial, and continue to add 0.25ml of N-methyl-2-pyrrolidone (NMP) solution. Place it on a magnetic stirrer and stir for another 2 hours to ensure that the carbon black is evenly mixed. Finally, add 0.12g of active substance to the mixture and add 0.5ml of N-methyl-2-pyrrolidone (NMP) solution. Continue stirring for 12 hours to ensure that the substances are fully mixed.

[0027] After slurrying, the slurry in the bottle was coated on copper foil with a coating machine to a thickness of 0.05mm, and then placed in a dryer for 30 minutes, and then transferred to a vacuum dryer at 80℃ for drying. After drying, it was cut into pieces and weighed. In a glove box filled with argon (O2 content <1ppm, water content <1ppm), the electrode, diaphragm, lithium sheet and nickel foam mesh were assembled into button cells using conventional methods and tested at 3000mA·g -1 The battery electrochemical performance test was carried out on a constant current charge and discharge system at a current density of .

[0028] The X-ray diffraction pattern of the interlayer hydrogen bond-regulated transition metal oxalate composite material prepared in this embodiment is as follows: Figure 1 As shown in the scanning electron microscope image Figure 2 Thermogravimetric curves are shown in a and d. Figure 3 As shown, the charge and discharge curve of lithium-ion battery at 3C is as follows Figure 6 , the capacity retention rate is as follows Figure 7 As shown. Figure 1 It can be seen that after the material is sintered at high temperature, the diffraction peak position of the material is shifted and the peak intensity is weak. This is mainly due to the loss of water molecules and hydrogen bonds between the structural layers, resulting in the destruction of the interlayer structure. Figure 2It can be seen that a large number of cracks appear in the material, which may be due to the decrease in the crystallinity of the material after sintering, and the morphology also appears more irregular shapes (square, rod-shaped, spherical and diamond-shaped). Figure 3 It can be seen that when the ferrous oxalate material with deionized water as solvent is sintered in an argon atmosphere, two relatively obvious weight loss phenomena occur during the thermal decomposition of ferrous oxalate containing crystal water. An obvious weight loss phenomenon occurs before 210 ° C, with a weight loss rate of 19.42%, which is consistent with the theoretical value of 20% (FeC2O4·2H2O=FeC2O4+2H2O); the second obvious weight loss phenomenon occurs after about 320 ° C. The second step reaction is the thermal decomposition of ferrous oxalate, that is, ferrous oxalate decomposes to produce CO, CO2 and FeO x (FeO, Fe2O3, Fe3O4).

[0029] Example 2: A transition metal oxalate interlayer hydrogen bond regulation strategy and its application are as follows:

[0030] (1) Weighing dihydrate oxalic acid and hydrous ferrous sulfate, respectively, and sintering and dehydrating them in an inert atmosphere, wherein the sintering temperatures are 120°C and 360°C, respectively, with a heating rate of 5°C / min and a holding time of 2.5 hours to obtain anhydrous oxalic acid and anhydrous ferrous sulfate;

[0031] (2) Weighing the anhydrous ferrous sulfate and ascorbic acid obtained in step (1) and adding them to an ethylene glycol solution, and electromagnetically stirring for 2 hours to obtain a ferrous sulfate solution; weighing the anhydrous oxalic acid obtained in step (1) and adding it to an ethylene glycol solution, and electromagnetically stirring for 2 hours to obtain an oxalic acid solution, wherein the mass ratio of ascorbic acid to anhydrous ferrous sulfate is 1:10, the molar ratio of anhydrous oxalic acid to anhydrous ferrous sulfate is 1.2:1, the mass concentration of the ferrous sulfate solution is 3.2%, and the mass concentration of the oxalic acid solution is 5.3%;

[0032] (3) Slowly adding the oxalic acid solution in step (2) to the ferrous sulfate solution, electromagnetically stirring for 30 minutes, and then transferring to a high-temperature and high-pressure hydrothermal reactor, the reaction temperature is 65°C, the reaction time is 12 hours, and after the reaction is completed, filtering, washing, and vacuum drying to obtain a transition metal oxalate precursor after interlayer hydrogen bond regulation;

[0033] (4) Under an argon or nitrogen inert atmosphere, the transition metal oxalate precursor with interlayer hydrogen bonds obtained in step (3) is sintered at 260° C. for 2.5 h to obtain a transition metal oxalate material regulated by interlayer hydrogen bonds.

[0034] After accurately weighing 0.02g of polyvinylidene fluoride (PVDF) powder, place it in a glass vial equipped with a rotor. Add 0.75ml of N-methyl-2-pyrrolidone (NMP) solution to the vial and stir it on a magnetic stirrer for 1 hour to allow the PVDF to fully dissolve. After stirring, add 0.06g of carbon black to the vial, and continue to add 0.25ml of N-methyl-2-pyrrolidone (NMP) solution. Place it on a magnetic stirrer and stir for another 2 hours to ensure that the carbon black is evenly mixed. Finally, add 0.12g of active substance to the mixture and add 0.5ml of N-methyl-2-pyrrolidone (NMP) solution. Continue stirring for 12 hours to ensure that the substances are fully mixed.

[0035] After slurrying, the slurry in the bottle was coated on copper foil with a coating machine to a thickness of 0.05mm, and then placed in a dryer for 30 minutes, and then transferred to a vacuum dryer at 80℃ for drying. After drying, it was cut into pieces and weighed. In a glove box filled with argon (O2 content <1ppm, water content <1ppm), the electrode, diaphragm, lithium sheet and nickel foam mesh were assembled into button cells using conventional methods and tested at 3000mA·g -1 The battery electrochemical performance test was carried out on a constant current charge and discharge system at a current density of .

[0036] The X-ray diffraction pattern of the interlayer hydrogen bond-regulated transition metal oxalate composite material prepared in this embodiment is as follows: Figure 1 As shown in the scanning electron microscope image Figure 2 b, e, the thermogravimetric curves are as follows Figure 4 As shown, the charge and discharge curve of lithium-ion battery at 3C is as follows Figure 6 , the capacity retention rate is as follows Figure 7 As shown. Figure 1 It can be seen that when ethylene glycol is used as the solvent, the changes in the diffraction peaks are similar to those in Example 1, but the intensities of some diffraction peaks may be slightly different. This reflects that the effect of ethylene glycol as a solvent on the crystal structure of the material is different from that of deionized water, but it will also cause a certain degree of damage to the interlayer structure after sintering. Figure 2 It can be seen that after the material is sintered at high temperature, the interlayer structure collapses more seriously. Figure 4 It can be seen that the ferrous oxalate material using ethylene glycol as a solvent also has two obvious weight loss phenomena. The first weight loss process also ends before 210℃, and the second weight loss process is between 320℃ and 400℃. Figure 6 、 7 It can be seen that the first charge and discharge capacity at a current density of 3C is 1587.92 mAh g -1 However, the battery capacity retention rate is poor, only 35%. This is because after the ferrous oxalate material is sintered at high temperature, the interlayer structure is severely damaged and the material collapses.

[0037] Example 3: A transition metal oxalate interlayer hydrogen bond regulation strategy and its application in this example are as follows:

[0038] (1) Weighing dihydrate oxalic acid and hydrous ferrous sulfate, respectively, and sintering and dehydrating them in an inert atmosphere at temperatures of 125°C and 350°C, respectively, with a heating rate of 5°C / min and a holding time of 3 hours to obtain anhydrous oxalic acid and anhydrous ferrous sulfate;

[0039] (2) Weighing the anhydrous ferrous sulfate and ascorbic acid obtained in step (1) and adding them to a glycerol solution, and electromagnetically stirring for 2 hours to obtain a ferrous sulfate solution; weighing the anhydrous oxalic acid obtained in step (1) and adding it to a glycerol solution, and electromagnetically stirring for 2 hours to obtain an oxalic acid solution, wherein the mass ratio of ascorbic acid to anhydrous ferrous sulfate is 1:11, the molar ratio of anhydrous oxalic acid to anhydrous ferrous sulfate is 1:1, the mass concentration of the ferrous sulfate solution is 3%, and the mass concentration of the oxalic acid solution is 4.7%;

[0040] (3) Slowly adding the oxalic acid solution in step (2) to the ferrous sulfate solution, electromagnetically stirring for 30 minutes, and then transferring to a high-temperature and high-pressure hydrothermal reactor, the reaction temperature is 60°C, the reaction time is 12 hours, and after the reaction is completed, filtering, washing, and vacuum drying to obtain a transition metal oxalate precursor after interlayer hydrogen bond regulation;

[0041] (4) Under an argon or nitrogen inert atmosphere, the transition metal oxalate precursor with interlayer hydrogen bonds obtained in step (3) is sintered at 250° C. for 3 h to obtain a transition metal oxalate material regulated by interlayer hydrogen bonds.

[0042] After accurately weighing 0.02g of polyvinylidene fluoride (PVDF) powder, place it in a glass vial equipped with a rotor. Add 0.75ml of N-methyl-2-pyrrolidone (NMP) solution to the vial and stir it on a magnetic stirrer for 1 hour to allow the PVDF to fully dissolve. After stirring, add 0.06g of carbon black to the vial, and continue to add 0.25ml of N-methyl-2-pyrrolidone (NMP) solution. Place it on a magnetic stirrer and stir for another 2 hours to ensure that the carbon black is evenly mixed. Finally, add 0.12g of active substance to the mixture and add 0.5ml of N-methyl-2-pyrrolidone (NMP) solution. Continue stirring for 12 hours to ensure that the substances are fully mixed.

[0043] After slurrying, the slurry in the bottle was coated on copper foil with a coating machine to a thickness of 0.05mm, and then placed in a dryer for 30 minutes, and then transferred to a vacuum dryer at 80℃ for drying. After drying, it was cut into pieces and weighed. In a glove box filled with argon (O2 content <1ppm, water content <1ppm), the electrode, diaphragm, lithium sheet and nickel foam mesh were assembled into button cells using conventional methods and tested at 3000mA·g -1 The battery electrochemical performance test was carried out on a constant current charge and discharge system at a current density of .

[0044] The X-ray diffraction pattern of the interlayer hydrogen bond-regulated transition metal oxalate composite material prepared in this embodiment is as follows: Figure 1 As shown in the scanning electron microscope image Figure 2 c, f, the thermogravimetric curves are as follows Figure 5 As shown, the charge and discharge curve of lithium-ion battery at 3C is as follows Figure 6 , the capacity retention rate is as follows Figure 7 shown. Figure 1 This shows that the use of glycerol as a solvent may result in slightly smaller diffraction peak shifts and intensity reductions than in Examples 1 and 2. This indicates that the hydrogen bond network formed by glycerol has a relatively better effect on maintaining the interlayer structure during high-temperature sintering, resulting in a relatively lower degree of damage to the crystal structure. Figure 2 It can be seen that there are still many pores inside the ferrous oxalate material after sintering at 250℃, which provide a smoother diffusion channel, accelerating the diffusion rate of lithium ions and turning the surface into a flocculent shape. Before sintering, the shape was rectangular, but after high-temperature sintering, due to material shedding and other reasons, spherical, square and other irregular shapes appeared. Figure 5 It can be seen that the thermogravimetric curve with propylene glycol as solvent is roughly the same as that of ethylene glycol, but different from that of deionized water, indicating that more water is removed between the layers. This may be because the interlayer distance of ferrous oxalate synthesized with ethylene glycol and propylene glycol as solvents is farther, and the interlayer void space is relatively larger, which can store more water. Figure 6 、 7 It can be seen that the material prepared in this example exhibits excellent cycle stability and capacity retention as a negative electrode material for lithium-ion batteries, with an initial discharge capacity of 1509.53 mAh g -1 After 400 cycles, there is still 1101.97 mAh g -1 The discharge specific capacity of the material was 1.577 W / m, and the capacity retention rate was as high as 73%. The capacity curve showed a slight downward trend before turning into a clear upward trend. This is because the material has a large internal void, which facilitates the diffusion of lithium ions and can store more lithium, resulting in electrochemical performance that is superior to the materials in Examples 1 and 2. This demonstrates the effectiveness of the present invention in optimizing the performance of transition metal oxalate composite materials through the synergistic effect of solvent regulation and sintering process.

[0045] Example 4: A transition metal oxalate interlayer hydrogen bond regulation strategy and its application in this example are as follows:

[0046] (1) Weighing dihydrate oxalic acid and hydrous cobalt sulfate, respectively, and sintering and dehydrating them in an inert atmosphere, wherein the sintering temperatures are 85°C and 300°C, respectively, with a heating rate of 3°C / min and a holding time of 3 hours to obtain anhydrous oxalic acid and anhydrous cobalt sulfate;

[0047] (2) Weighing the anhydrous cobalt sulfate and ascorbic acid obtained in step (1) and adding them to a deionized water-ethanol mixed solution, and electromagnetically stirring for 2 hours to obtain a cobalt sulfate solution; weighing the anhydrous oxalic acid obtained in step (1) and adding it to ethanol, and electromagnetically stirring for 2 hours to obtain an oxalic acid solution, wherein the volume ratio of deionized water to ethanol is 1:5, the mass ratio of ascorbic acid to anhydrous cobalt sulfate is 1:8, the molar ratio of anhydrous oxalic acid to anhydrous cobalt sulfate is 2:1, the mass concentration of the cobalt sulfate solution is 4.6%, and the mass concentration of the oxalic acid solution is 9.8%;

[0048] (3) Slowly adding the oxalic acid solution in step (2) to the cobalt sulfate solution, electromagnetically stirring for 20 minutes, and then transferring to a high-temperature and high-pressure hydrothermal reactor, the reaction temperature is 120°C, the reaction time is 8 hours, and after the reaction is completed, filtering, washing, and vacuum drying to obtain a transition metal oxalate precursor after interlayer hydrogen bond regulation;

[0049] (4) Under an argon inert atmosphere, the transition metal oxalate precursor with interlayer hydrogen bonds obtained in step (3) is sintered at 180° C. for 4 h to obtain a transition metal oxalate material regulated by interlayer hydrogen bonds.

[0050] After accurately weighing 0.02g of polyvinylidene fluoride (PVDF) powder, place it in a glass vial equipped with a rotor. Add 0.75ml of N-methyl-2-pyrrolidone (NMP) solution to the vial and stir it on a magnetic stirrer for 1 hour to allow the PVDF to fully dissolve. After stirring, add 0.06g of carbon black to the vial, and continue to add 0.25ml of N-methyl-2-pyrrolidone (NMP) solution. Place it on a magnetic stirrer and stir for another 2 hours to ensure that the carbon black is evenly mixed. Finally, add 0.12g of active substance to the mixture and add 0.5ml of N-methyl-2-pyrrolidone (NMP) solution. Continue stirring for 12 hours to ensure that the substances are fully mixed.

[0051] After slurrying, the slurry in the bottle was coated on copper foil with a coating machine to a thickness of 0.05mm, and then placed in a dryer for 30 minutes, and then transferred to a vacuum dryer at 80℃ for drying. After drying, it was cut into pieces and weighed. In a glove box filled with argon (O2 content <1ppm, water content <1ppm), the electrode, diaphragm, lithium sheet and nickel foam mesh were assembled into button cells using conventional methods and tested at 3000mA·g -1 The battery electrochemical performance test was carried out on a constant current charge and discharge system at a current density of .

[0052] Example 5: A transition metal oxalate interlayer hydrogen bond regulation strategy and its application in this example are as follows:

[0053] (1) Weighing dihydrate oxalic acid and a hydrated nickel magnesium sulfate mixture, respectively, and sintering and dehydrating them in an inert atmosphere, wherein the sintering temperatures are 100° C. and 320° C., respectively, with a heating rate of 5° C. / min and a holding time of 5 h to obtain anhydrous oxalic acid and anhydrous nickel magnesium sulfate;

[0054] (2) Weighing the anhydrous nickel magnesium sulfate and ascorbic acid obtained in step (1) and adding them to a deionized water-ethylene glycol mixed solution, and electromagnetically stirring for 1 hour to obtain a nickel magnesium sulfate solution; weighing the anhydrous oxalic acid obtained in step (1) and adding it to the ethylene glycol solution, and electromagnetically stirring for 1 hour to obtain an oxalic acid solution, wherein the volume ratio of deionized water to ethylene glycol is 1:10, the mass ratio of ascorbic acid to anhydrous nickel magnesium sulfate is 1:9, the molar ratio of anhydrous oxalic acid to anhydrous nickel magnesium sulfate is 4:1, the mass concentration of the nickel magnesium sulfate solution is 10.7%, and the mass concentration of the oxalic acid solution is 15.7%;

[0055] (3) Slowly adding the oxalic acid solution in step (2) to the nickel magnesium sulfate solution, electromagnetically stirring for 40 minutes, and then transferring to a high-temperature and high-pressure hydrothermal reactor, the reaction temperature is 80°C, the reaction time is 15 hours, and after the reaction is completed, filtering, washing, and vacuum drying to obtain a transition metal oxalate precursor after interlayer hydrogen bond regulation;

[0056] (4) Under a nitrogen inert atmosphere, the transition metal oxalate precursor with interlayer hydrogen bonds obtained in step (3) is sintered at 250° C. for 4 h to obtain a transition metal oxalate material regulated by interlayer hydrogen bonds.

[0057] After accurately weighing 0.02g of polyvinylidene fluoride (PVDF) powder, place it in a glass vial equipped with a rotor. Add 0.75ml of N-methyl-2-pyrrolidone (NMP) solution to the vial and stir it on a magnetic stirrer for 1 hour to allow the PVDF to fully dissolve. After stirring, add 0.06g of carbon black to the vial, and continue to add 0.25ml of N-methyl-2-pyrrolidone (NMP) solution. Place it on a magnetic stirrer and stir for another 2 hours to ensure that the carbon black is evenly mixed. Finally, add 0.12g of active substance to the mixture and add 0.5ml of N-methyl-2-pyrrolidone (NMP) solution. Continue stirring for 12 hours to ensure that the substances are fully mixed.

[0058] After slurrying, the slurry in the bottle was coated on copper foil with a coating machine to a thickness of 0.05mm, and then placed in a dryer for 30 minutes, and then transferred to a vacuum dryer at 80℃ for drying. After drying, it was cut into pieces and weighed. In a glove box filled with argon (O2 content <1ppm, water content <1ppm), the electrode, diaphragm, lithium sheet and nickel foam mesh were assembled into button cells using conventional methods and tested at 3000mA·g -1 The battery electrochemical performance test was carried out on a constant current charge and discharge system at a current density of .

[0059] Example 6: A transition metal oxalate interlayer hydrogen bond regulation strategy and its application in this example are as follows:

[0060] (1) Weighing dihydrate oxalic acid and a mixture of hydrous manganese copper sulfate, respectively, and placing them in an inert atmosphere for sintering and dehydration, wherein the sintering temperatures are 150°C and 450°C, respectively, with a heating rate of 5°C / min, and the temperature is kept for 2 hours to obtain anhydrous oxalic acid and anhydrous manganese copper sulfate;

[0061] (2) Weighing the anhydrous manganese copper sulfate and ascorbic acid obtained in step (1) and adding them to a deionized water-glycerol mixed solution, and electromagnetically stirring for 3 hours to obtain a manganese copper sulfate solution; weighing the anhydrous oxalic acid obtained in step (1) and adding it to a glycerol solution, and electromagnetically stirring for 3 hours to obtain an oxalic acid solution, wherein the volume ratio of deionized water to glycerol is 3:10, the mass ratio of ascorbic acid to anhydrous manganese copper sulfate is 1:12, the molar ratio of anhydrous oxalic acid to anhydrous manganese copper sulfate is 5:1, the mass concentration of the manganese copper sulfate solution is 21.4%, and the mass concentration of the oxalic acid solution is 32.7%;

[0062] (3) Slowly adding the oxalic acid solution in step (2) to the manganese copper sulfate solution, electromagnetically stirring for 30 minutes, and then transferring to a high-temperature and high-pressure hydrothermal reactor, the reaction temperature is 70°C, the reaction time is 18 hours, and after the reaction is completed, filtering, washing, and vacuum drying to obtain a transition metal oxalate precursor after interlayer hydrogen bond regulation;

[0063] (4) Under an argon or nitrogen inert atmosphere, the transition metal oxalate precursor with interlayer hydrogen bonds obtained in step (3) is sintered at 280° C. for 6 hours to obtain a transition metal oxalate material regulated by interlayer hydrogen bonds.

[0064] After accurately weighing 0.02g of polyvinylidene fluoride (PVDF) powder, place it in a glass vial equipped with a rotor. Add 0.75ml of N-methyl-2-pyrrolidone (NMP) solution to the vial and stir it on a magnetic stirrer for 1 hour to allow the PVDF to fully dissolve. After stirring, add 0.06g of carbon black to the vial, and continue to add 0.25ml of N-methyl-2-pyrrolidone (NMP) solution. Place it on a magnetic stirrer and stir for another 2 hours to ensure that the carbon black is evenly mixed. Finally, add 0.12g of active substance to the mixture and add 0.5ml of N-methyl-2-pyrrolidone (NMP) solution. Continue stirring for 12 hours to ensure that the substances are fully mixed.

[0065] After slurrying, the slurry in the bottle was coated on copper foil with a coating machine to a thickness of 0.05mm, and then placed in a dryer for 30 minutes, and then transferred to a vacuum dryer at 80℃ for drying. After drying, it was cut into pieces and weighed. In a glove box filled with argon (O2 content <1ppm, water content <1ppm), the electrode, diaphragm, lithium sheet and nickel foam mesh were assembled into button cells using conventional methods and tested at 3000mA·g -1 The battery electrochemical performance test was carried out on a constant current charge and discharge system at a current density of .

[0066] The above describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A transition metal oxalate interlayer hydrogen bond regulation strategy, characterized in that The specific steps are as follows: (1) Weighing dihydrate oxalic acid and aqueous sulfate, respectively, and calcining and dehydrating them in an inert atmosphere to obtain anhydrous oxalic acid and anhydrous sulfate; (2) Weighing the anhydrous sulfate obtained in step (1) and adding it to deionized water or alcohol or a mixed solution of the two with ascorbic acid, and stirring with an electromagnetic field for 1-3 hours to obtain a sulfate solution; weighing the anhydrous oxalic acid obtained in step (1) and adding it to the alcohol solution, and stirring with an electromagnetic field for 1-3 hours to obtain an oxalic acid solution; (3) slowly adding the oxalic acid solution in step (2) to the sulfate solution, stirring with electromagnetic stirring for 10-60 minutes, and then transferring to a high-temperature and high-pressure hydrothermal reactor for reaction. After the reaction is completed, filtering, washing, and vacuum drying are performed to obtain a transition metal oxalate precursor after interlayer hydrogen bond regulation; (4) Sintering the transition metal oxalate precursor with interlayer hydrogen bonds obtained in step (3) for 1 to 6 hours under an inert atmosphere of argon or nitrogen to obtain a transition metal oxalate material regulated by interlayer hydrogen bonds.

2. A transition metal oxalate interlayer hydrogen bond regulation strategy according to claim 1, characterized in that: In step (1), the aqueous sulfate is one of ferrous salt, cobalt salt, nickel salt, manganese salt, zinc salt, and copper salt, or a mixture of several of them in any ratio; in step (1), the sintering temperature of dihydrate oxalic acid is 80°C to 150°C, and the temperature is kept for 1 to 3 hours; the sintering temperature of aqueous sulfate is 300°C to 450°C, and the temperature is kept for 2 to 6 hours, and the heating rate is 1-5°C / min.

3. The transition metal oxalate interlayer hydrogen bond regulation strategy according to claim 1, characterized in that: The alcohol in step (2) is one of ethanol, ethylene glycol, and glycerol, or a mixture of any of the above. The volume ratio of deionized water to alcohol is 1:10 to 3:10, the mass ratio of ascorbic acid to anhydrous sulfate is 1:8 to 1:12, the molar ratio of anhydrous oxalic acid to anhydrous sulfate is 1:1 to 5:1, the mass concentration of the sulfate solution is 3% to 30%, and the mass concentration of the oxalic acid solution is 3% to 50%.

4. The transition metal oxalate interlayer hydrogen bond regulation strategy according to claim 1, characterized in that: In step (3), the high temperature and high pressure hydrothermal reaction temperature is 50° C. to 120° C., and the reaction time is 8 to 24 hours.

5. The transition metal oxalate interlayer hydrogen bond regulation strategy according to claim 1, characterized in that: In step (4), the sintering temperature of the transition metal oxalate precursor is 150°C to 280°C.

6. Application of a transition metal oxalate interlayer hydrogen bond regulation strategy according to claims 1 to 5, characterized in that: The prepared hydrogen bond-regulated transition metal oxalate is used as a negative electrode material for lithium-ion batteries.

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