Flaky mesoporous pbO@C material, preparation method thereof, negative electrode and lead-acid battery

Abstract

The application provides a preparation method of a sheet-shaped mesoporous PbO@C material, and comprises the following steps: dissolving glucose, an alkali metal salt template agent and a cleavable soluble lead salt in water, heating and stirring until the solution is thick or evaporated to dryness, drying to obtain a mixture; calcining and carbonizing the mixture under an inert atmosphere or a nitrogen atmosphere; washing and drying the material obtained by carbonization, and the sheet-shaped mesoporous PbO@C material is obtained. The composite material with the structure has a current buffering effect on the pole plate, can reduce the polarization of the negative electrode, improve the conductive performance of the pole plate, effectively inhibit the sulfation of the negative pole plate, and improve the utilization rate of the active material; the sheet-shaped mesoporous PbO@C material can effectively inhibit the hydrogen evolution reaction and avoid the loss of the electrolyte; and in the material, the in-situ generated PbO can effectively hinder the self-stacking of the sheet layer, improve the dispersibility of the carbon material in the negative electrode, accelerate the transmission of ions and electrons, and promote the electrode to exhibit excellent electrochemical performance and cycle stability.

Description

Technical Field

[0001] This invention belongs to the technical field of lead-acid battery electrode materials, specifically relating to sheet-like mesoporous PbO@C materials and their preparation methods. Background Technology

[0002] Currently, lead-acid batteries still play an indispensable role in the rechargeable battery market, especially as starting power for the automotive industry. However, the high-rate partial state of charge (HRPSoC) operating state can lead to reversible sulfation of the negative electrode active material, resulting in rapid failure of lead-acid batteries in electric vehicles.

[0003] In recent years, high-surface-area conductive carbon materials have been introduced to inhibit the sulfonation of the negative electrode plate and improve the HRPSoC cycle performance of lead-acid batteries. However, the carbon composite materials involved suffer from severe hydrogen evolution, which can rapidly dry out the electrolyte and increase the hazard of the battery system.

[0004] To address this, researchers have modified carbon materials with surface functional groups to alter their surface chemistry and suppress hydrogen evolution. For example, activated carbon (AC) modified with alkaline surface functional groups can inhibit the hydrogen evolution reaction (HER), while acidic surface functional groups can promote this process. An alternative strategy to suppress HER in the negative electrode is to modify the lead negative electrode with additives. For instance, lead oxide can be loaded onto the surface of carbon materials to increase the HER overpotential on the carbon material surface, thus suppressing HER. This also increases the affinity of the carbon material for the negative electrode lead paste, enhancing the bonding between the composite material and the negative electrode active material (NAM) during HRPSoC cycling and improving the high-rate fast charge-discharge cycle performance of the battery. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a sheet-like mesoporous PbO@C material, its preparation method, a negative electrode, and a lead-acid battery.

[0006] To achieve the above objectives, the present invention proposes the following solution:

[0007] This invention provides a method for preparing a sheet-like mesoporous PbO@C material, comprising:

[0008] S1. Dissolve glucose, alkali metal salt template agent and cleavable soluble lead salt in water, heat and stir until the solution is thick or evaporated to dryness, and then dry to obtain a mixture;

[0009] S2. The mixture is calcined and carbonized under an inert atmosphere or a nitrogen atmosphere;

[0010] S3. The carbonized material is washed and dried to obtain a plate-like mesoporous PbO@C material.

[0011] Preferably, the alkali metal salt template agent is sodium chloride and / or potassium chloride.

[0012] Preferably, the soluble lead salt is lead acetate and / or lead nitrate.

[0013] Preferably, the mass ratio of glucose, alkali metal salt template agent and soluble lead salt is 4-8:15-20:0.3-0.5.

[0014] Preferably, in step S2, the calcination temperature is 700–1000°C; the calcination time is 3–5 h; and the calcination heating rate is 1–5°C / min.

[0015] Preferably, in step S1, the heating temperature is 80–90°C.

[0016] As a general inventive concept, the present invention also provides a sheet-like mesoporous PbO@C material, which is prepared by the aforementioned preparation method.

[0017] As a general inventive concept, the present invention also provides a lead-acid battery negative electrode, including an additive, said additive being the aforementioned sheet-like mesoporous PbO@C material.

[0018] As a general inventive concept, the present invention also provides a lead-acid battery, including the aforementioned negative electrode.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The preparation method of this invention can prepare sheet-like mesoporous PbO@C materials. This composite material structure has a buffering effect on the electrode plate, which can reduce the polarization of the negative electrode and improve the conductivity of the electrode plate, thereby effectively inhibiting the sulfation of the negative electrode plate and improving the utilization rate of active materials. The prepared sheet-like mesoporous PbO@C material has a higher hydrogen evolution overpotential, which can reduce the hydrogen evolution reaction during battery charging and avoid electrolyte loss. In addition, the PbO generated in situ in this material can effectively hinder the self-stacking of the sheets, improve the dispersion of carbon materials in the negative electrode, thereby effectively accelerating the transport of ions and electrons and promoting the electrode to exhibit excellent electrochemical performance and cycle stability.

[0021] The preparation method of the present invention, by controlling the amounts of raw materials, glucose and template agent within a certain proportion range, can effectively improve the cycle performance of the negative electrode while controlling the hydrogen evolution potential of the sheet-like mesoporous PbO@C material within a reasonable range. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a SEM image of the sheet-like mesoporous PbO@C material prepared in Example 1.

[0024] Figure 2 The image shows the XRD pattern of the sheet-like mesoporous PbO@C material prepared in Example 1.

[0025] Figure 3 The image shows a SEM image of the mesoporous PbO@C material prepared in Comparative Example 3.

[0026] Figure 4 The hydrogen evolution rate diagrams are for the negative electrodes of the lead paste prepared in Examples 1-4 and Comparative Examples 1-3 that have been cured.

[0027] Figure 5 HRPSoC cycling diagrams of lead-acid batteries assembled with negative electrodes prepared in Examples 1-4 and Comparative Examples 1-3. Detailed Implementation

[0028] Some embodiments of the present invention provide a method for preparing a sheet-like mesoporous PbO@C material, comprising:

[0029] S1. Dissolve glucose, alkali metal salt template agent and cleavable soluble lead salt in water, heat and stir until the solution is thick or evaporated to dryness, and then dry to obtain a mixture;

[0030] S2. The mixture is calcined and carbonized under an inert atmosphere or a nitrogen atmosphere;

[0031] S3. The carbonized material is washed and dried to obtain a plate-like mesoporous PbO@C material.

[0032] In some preferred embodiments, the alkali metal salt template agent is sodium chloride and / or potassium chloride.

[0033] In some preferred embodiments, the soluble lead salt is lead acetate and / or lead nitrate.

[0034] In some preferred embodiments, the mass ratio of glucose, alkali metal salt template agent, and soluble lead salt is 4–8:15–20:0.3–0.5, more preferably 4.5–7.5:16–19:0.3–0.5. When the alkali metal salt content is too high, it interferes with the formation of lamellar carbon; if the content is too low, it reduces the number of mesoporous structures, decreasing the active sites during electrochemical deposition of the negative electrode. When the glucose content is too high, it results in excessive carbon content, causing severe hydrogen evolution; when the carbon content is too low, it exacerbates sulfation of the negative electrode during HRPSoC cycling. Controlling the amounts of raw materials, glucose, and template agent within a certain range can effectively improve the cycling performance of the negative electrode while keeping the hydrogen evolution potential of the lamellar mesoporous PbO@C material within a reasonable range.

[0035] In some preferred embodiments, in step S2, the calcination temperature is 700–1000°C; the calcination time is 3–5 hours; and the calcination heating rate is 1–5°C / min. If the calcination temperature is too high or the calcination time is too long, the size of the carbon material will increase, thereby reducing the material's dispersibility in the negative electrode and increasing the hydrogen evolution reaction area. If the calcination temperature is too low, the graphitization effect will not be achieved, reducing the material's conductivity and consequently reducing the conductivity of the negative electrode plate.

[0036] In some preferred embodiments, the heating temperature in step S1 is 80-90°C.

[0037] Some embodiments of the present invention also provide a sheet-like mesoporous PbO@C material, which is prepared using the aforementioned preparation method.

[0038] Some embodiments of the present invention also provide a lead-acid battery negative electrode, including an additive, said additive being the aforementioned sheet-like mesoporous PbO@C material.

[0039] Some embodiments of the present invention also provide a lead-acid battery, including the aforementioned negative electrode.

[0040] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0042] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0043] Example 1

[0044] Step 1: Weigh 6g of glucose monohydrate, 18g of NaCl and 0.4g of lead acetate and dissolve them in 80mL of deionized water. Heat and stir at 85℃ until the solution becomes thick, then transfer it to an oven at 100℃ to dry.

[0045] Step 2: Calcine the dried mixture at 800°C for 3 hours under an argon atmosphere with a heating rate of 3°C / min.

[0046] Step 3: Wash the carbonized powder sample with 100ml of deionized water and vacuum filter it to remove the (NaCl) template. Then dry it in a 100℃ oven to obtain sheet-like mesoporous PbO@C material.

[0047] SEM images of the obtained sheet-like mesoporous PbO@C material are shown below. Figure 1 As shown. From Figure 1 It can be seen that the carbon material exhibits an irregular blocky or sheet-like structure with a size ranging from 1 to 2 micrometers, and a small amount of lead oxide crystals are dispersed around the carbon material.

[0048] The XRD pattern of the obtained lamellar mesoporous PbO@C material is shown below. Figure 2 As stated. From Figure 2 It can be seen that there are two diffraction peaks at 2θ of 22.3° and 45°, corresponding to the (002) and (001) crystal planes of graphitic carbon, indicating that the PbO@C material has a certain degree of graphitization.

[0049] The ingredients for the negative electrode lead paste were prepared according to a specific formula. The required ingredients were: lead powder with an oxidation degree of 76%, 1.41 g / mL sulfuric acid solution, barium sulfate, lignin, humic acid, short fibers, distilled water, acetylene black, and the previously prepared mesoporous PbO@C material. The sulfuric acid solution accounted for 7% of the lead powder's mass; barium sulfate accounted for 2%; lignin accounted for 0.9%; humic acid accounted for 0.6%; short fibers accounted for 0.03%; distilled water accounted for 9%; acetylene black accounted for 1.8%; and the mesoporous PbO@C material accounted for 1.0%. The above ingredients were then mixed to form a paste. The resulting lead paste had an apparent density of 4.1 g / cm³. 3 .

[0050] The negative electrode lead paste prepared above is coated onto the negative electrode grid, and then subjected to conventional curing and formation to obtain the negative electrode plate.

[0051] Example 2

[0052] Step 1: Weigh 8g of glucose monohydrate, 20g of NaCl and 0.5g of lead acetate and dissolve them in 80mL of deionized water. Heat and stir at 85℃ until the solution becomes thick, then transfer it to an oven at 100℃ to dry.

[0053] Step 2: Calcine the dried mixture at 800°C for 3 hours under an argon atmosphere with a heating rate of 3°C / min.

[0054] Step 3: Wash the carbonized powder sample with 100ml of deionized water and vacuum filter it to remove the (NaCl) template. Then dry it in a 100℃ oven to obtain sheet-like mesoporous PbO@C material.

[0055] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0056] Example 3

[0057] Step 1: Weigh 4g of glucose monohydrate, 20g of NaCl, and 0.5g of lead acetate and dissolve them in 80mL of deionized water. Heat and stir at 85℃ until the solution becomes thick, then transfer it to an oven at 100℃ to dry.

[0058] Step 2: Calcine the dried mixture at 800°C for 3 hours under an argon atmosphere with a heating rate of 3°C / min.

[0059] Step 3: Wash the carbonized powder sample with 100ml of deionized water and vacuum filter it to remove the (NaCl) template. Then dry it in a 100℃ oven to obtain sheet-like mesoporous PbO@C material.

[0060] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0061] Example 4

[0062] Step 1: Weigh 8g of glucose monohydrate, 15g of NaCl and 0.3g of lead acetate and dissolve them in 80mL of deionized water. Heat and stir at 85℃ until the solution becomes thick, then transfer it to an oven at 100℃ to dry.

[0063] Step 2: Calcine the dried mixture at 800°C for 3 hours under an argon atmosphere with a heating rate of 3°C / min.

[0064] Step 3: Wash the carbonized powder sample with 100ml of deionized water and vacuum filter it to remove the (NaCl) template. Then dry it in a 100℃ oven to obtain sheet-like mesoporous PbO@C material.

[0065] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0066] Example 5

[0067] Step 1: Weigh 6g of glucose monohydrate, 18g of KCl and 0.4g of lead nitrate and dissolve them in 80mL of deionized water. Heat and stir at 85℃ until the solution becomes thick, then transfer it to an oven at 100℃ to dry.

[0068] Step 2: Calcine the dried mixture at 700°C for 5 hours under an argon atmosphere with a heating rate of 1°C / min.

[0069] Step 3: Wash the carbonized powder sample with 100ml of deionized water and vacuum filter it to remove the (KCl) template. Then dry it in a 90℃ oven to obtain sheet-like mesoporous PbO@C material.

[0070] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0071] Example 6

[0072] Step 1: Weigh 6g of glucose monohydrate, 18g of KCl and 0.4g of lead nitrate and dissolve them in 80mL of deionized water. Heat and stir at 85℃ until the solution becomes thick, then transfer it to an oven at 100℃ to dry.

[0073] Step 2: Calcine the dried mixture at 1000℃ for 3 hours under an argon atmosphere with a heating rate of 5℃ / min.

[0074] Step 3: Wash the carbonized powder sample with 100ml of deionized water and vacuum filter it to remove the (KCl) template. Then dry it in an oven at 110℃ to obtain the sheet-like mesoporous PbO@C material.

[0075] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0076] Comparative Example 1

[0077] Step 1: Weigh 2g of glucose monohydrate, 20g of NaCl and 0.5g of lead acetate and dissolve them in 80mL of deionized water. Heat and stir at 85℃ until the solution becomes thick, then transfer it to an oven at 100℃ to dry.

[0078] Step 2: Calcine the dried mixture at 700°C for 5 hours under an argon atmosphere with a heating rate of 1°C / min.

[0079] Step 3: Wash the carbonized powder sample with 100ml of deionized water and vacuum filter it to remove the (NaCl) template. Then dry it in a 100℃ oven to obtain mesoporous PbO@C material.

[0080] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0081] Comparative Example 2

[0082] Step 1: Weigh 8g of glucose monohydrate, 10g of NaCl and 0.2g of lead acetate and dissolve them in 80mL of deionized water. Heat and stir at 85℃ until the solution becomes thick, then transfer it to an oven at 100℃ to dry.

[0083] Step 2: Calcine the dried mixture at 700°C for 5 hours under an argon atmosphere with a heating rate of 1°C / min.

[0084] Step 3: Wash the carbonized powder sample with 100ml of deionized water and vacuum filter it to remove the (NaCl) template. Then dry it in a 100℃ oven to obtain sheet-like mesoporous PbO@C material.

[0085] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0086] Comparative Example 3

[0087] The only difference between this comparative example and Example 1 is that the carbon source used is citric acid.

[0088] SEM images of the obtained mesoporous PbO@C material are shown below. Figure 3 As shown.

[0089] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0090] Comparative Example 4

[0091] The comparative example differs from the embodiment only in that, in step two, the calcination is carried out at 1100°C for 3 hours.

[0092] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0093] Comparative Example 5

[0094] The difference between this comparative example and Example 1 is that the addition of lead acetate is omitted in step one, and the material obtained in step three is a single carbon material.

[0095] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0096] Comparative Example 6

[0097] The difference between this comparative example and Example 1 is that the negative electrode lead paste does not contain the lead-carbon material of Example 1.

[0098] Lead paste and negative electrode plate were prepared according to the method in Example 1.

[0099] Take 25g of the lead paste prepared in Examples 1-6 and Comparative Examples 1-6, apply it to a plate, and perform conventional curing.

[0100] Using the cured negative electrode plate as the working electrode, with a diameter of 2×2cm 2 A platinum sheet electrode was used as the counter electrode, and Hg / Hg₂SO₄ / K₂SO₄ was used as the reference electrode to assemble a conventional three-electrode system for LSV testing. Electrochemical tests of all cells were performed in a 1.28 g / mL sulfuric acid solution. The hydrogen evolution rate at the cathode was evaluated using linear sweep voltammetry (LSV), with LSV detection at a scan rate of 5 mV / s in the range of -1.60 V to -1.00 V. The corresponding hydrogen evolution current at -1.6 V is shown in Table 1 for easy comparison. Figure 4 The diagram shows the hydrogen evolution rate of the negative electrode cured with lead paste in Examples 1-4 and Comparative Examples 1-3.

[0101] The negative electrode plates prepared in Examples 1-6 and Comparative Examples 1-6 were conventionally formed and then assembled into lead-acid batteries for high-rate fast charge-discharge (HRPSoC) testing.

[0102] Battery assembly: After assembling the prepared negative electrode plate and two positive electrode plates, place them in a battery mold, add 1.28 g / mL sulfuric acid as electrolyte, seal, and the battery is made.

[0103] High Rate Fast Charge / Discharge (HRPSoC) Test: (1) Fully charge the battery at a rate of 0.1C, and then discharge it at a rate of 1C to 50% state of charge (SoC). (2) Charge / discharge cycle: Charge at 1C rate for 15 seconds, rest for 5 seconds, discharge at 1C rate for 15 seconds, and rest for 5 seconds. Measure the battery voltage at the end of each charge and discharge cycle. The cycle ends when the discharge cut-off voltage or charge termination voltage is 1.7V or 2.9V. The test results are shown in Table 1, where... Figure 5 The diagram shows HRPSoC cycling schematics of lead-acid batteries with negative electrode assemblies in Examples 1-4 and Comparative Examples 1-3.

[0104] Table 1

[0105]

[0106] Table 1 shows that when glucose is not used as the carbon source but other carbon sources, such as citric acid, not only does the hydrogen evolution current increase significantly, but the cycling performance is also poor. Compared with mesoporous carbon materials, the hydrogen evolution current of the composite material is significantly suppressed, and the cycling performance is significantly improved. When the carbon content is too high, the hydrogen evolution current increases significantly, leading to severe hydrogen evolution. When the carbon content is too low, the cycling performance deteriorates significantly, and the number of HRPSoC cycles decreases significantly. Furthermore, when the alkali metal salt ratio is too high, it interferes with the formation of lamellar carbon, resulting in more severe hydrogen evolution. Conversely, when the alkali metal salt ratio is too low, the mesoporous structure decreases, which is detrimental to cycling performance. Figure 4 and Figure 5 It can be seen that the hydrogen evolution current corresponding to the products in Examples 1-4 is relatively small, and the cycle performance is relatively better.

[0107] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a sheet-like mesoporous PbO@C material, characterized in that, include: S1. Dissolve glucose, alkali metal salt template agent, and cleavable soluble lead salt in water, heat and stir until the solution is thick or evaporated to dryness, and dry to obtain a mixture; the alkali metal salt template agent is sodium chloride and / or potassium chloride; the mass ratio of glucose, alkali metal salt template agent, and soluble lead salt is 4-8:15-20:0.3-0.5; S2. The mixture is calcined and carbonized under an inert atmosphere or a nitrogen atmosphere; S3. The carbonized material is washed and dried to obtain a plate-like mesoporous PbO@C material.

2. The method for preparing the sheet-like mesoporous PbO@C material as described in claim 1, characterized in that, The soluble lead salt is lead acetate and / or lead nitrate.

3. The method for preparing the sheet-like mesoporous PbO@C material as described in claim 1, characterized in that, In step S2, the calcination temperature is 700–1000℃; the calcination time is 3–5 h; and the calcination heating rate is 1–5℃ / min.

4. The method for preparing the sheet-like mesoporous PbO@C material as described in claim 1, characterized in that, In step S1, the heating temperature is 80-90℃.

5. A sheet-like mesoporous PbO@C material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 4.

6. A negative electrode for a lead-acid battery, comprising an additive, characterized in that, The additive is the plate-like mesoporous PbO@C material as described in claim 5.

7. A lead-acid battery, characterized in that, Includes the negative electrode as described in claim 6.

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