A negative electrode additive, a preparation method and application thereof

Abstract

The application discloses a negative electrode additive and a preparation method and application thereof, and belongs to the technical field of metal oxide / biomass carbon composite materials and lead-carbon batteries. The application first carries out high-temperature activation treatment on apricot shell carbon in a potassium hydroxide melt, and then carries out a hydrothermal reaction on the apricot shell carbon in a potassium permanganate solution to obtain the negative electrode additive. The negative electrode additive has good compatibility with a negative electrode active material, has the advantages of conductivity, high electrocatalytic activity and the like, can effectively inhibit irreversible sulfation, and can improve battery capacity and increase battery cycle life.

Description

Technical Field

[0001] The invention relates to a negative electrode additive and a preparation method and application thereof, belonging to the technical field of metal oxide / biomass carbon composite materials and lead-carbon batteries. Background Art

[0002] Carbon batteries offer advantages such as fast charging, long cycle life, high cost-effectiveness, and high recovery rates, and hold great potential for development in the field of renewable energy storage. Lead-carbon batteries effectively prevent sulfation of the negative electrode, but the conversion of lead sulfate to metallic lead is not fully reversible. Under certain conditions, lead sulfate particles can accumulate on the negative electrode surface, leading to a gradual loss of battery capacity during subsequent discharge. This accumulation of lead sulfate is known as "hard sulfation." The most commonly used carbonaceous materials as additives for the negative electrode active material of lead-carbon batteries include activated carbon, graphite, carbon black, graphene, various carbon nanomaterials, and carbon composites.

[0003] Common carbon materials in lead-carbon battery negative electrodes primarily function through increased conductivity, double-layer capacitance, steric hindrance, increased electrode surface area, and electrocatalysis. While the introduction of carbon materials has alleviated the sulfation problem, the effects of a single carbon material are limited, failing to significantly improve battery cycle life. Furthermore, the serious issue of hydrogen evolution persists, making a comprehensive solution difficult. Summary of the Invention

[0004] In order to overcome the problems in the background technology, the purpose of the present invention is to provide a negative electrode additive and its preparation method and application. Applying the prepared negative electrode additive to the negative electrode of a lead-carbon battery can accelerate the ion transfer rate, improve the utilization rate of active substances and effectively alleviate irreversible sulfation.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] A method for preparing a negative electrode additive for inhibiting irreversible sulfation of a negative electrode comprises the following steps:

[0007] (1) drying the apricot shell activated carbon, placing the dried apricot shell activated carbon in a potassium hydroxide solution for high-temperature activation, and then drying to obtain activated apricot shell activated carbon, impregnating the activated apricot shell activated carbon with a hydrochloric acid solution, and then filtering, washing, and drying to obtain a carbon precursor;

[0008] (2) The carbon precursor is placed in a potassium permanganate solution for hydrothermal reaction, and finally washed and dried to obtain a negative electrode additive.

[0009] More preferably, the mass ratio of potassium hydroxide to apricot shell activated carbon is (1-3):1. Compared to the problems of low reactivity, high byproducts, and strong corrosiveness associated with activation of apricot shell activated carbon using calcium hydroxide or sodium hydroxide, potassium hydroxide can avoid these problems. Furthermore, within the range of "a mass ratio of potassium hydroxide to apricot shell activated carbon of (1-3):1" defined herein, potassium hydroxide has a good activation effect on the apricot shell activated carbon, constructs a suitable microporous structure, and prevents structural collapse. The activated apricot shell activated carbon, combined with multivalent manganese oxide, can inhibit sulfation and hydrogen evolution reactions in lead-carbon batteries.

[0010] More preferably, the temperature of the high-temperature activation is 650-850° C., and the time is 2 hours.

[0011] More preferably, the concentration of the hydrochloric acid solution is 2-3 mol / L, and the immersion time is 30-40 min.

[0012] More preferably, the concentration of the potassium permanganate solution is 0.04-0.16 mol / L, and the mass ratio of the carbon precursor to potassium permanganate is 1:0.5-1:2.

[0013] More preferably, the temperature of the hydrothermal reaction is 100-150° C., and the time is 1-3 hours.

[0014] The present invention also claims protection for the negative electrode additive prepared by the method for preparing the negative electrode additive for inhibiting irreversible sulfation of the negative electrode.

[0015] The present invention also claims that the negative electrode additive is used as an additive for lead-carbon battery negative electrode materials.

[0016] The negative electrode additive prepared by the present invention not only realizes charge storage by adsorbing and desorbing electrolyte ions on the electrode surface through diffusion, but also accelerates the kinetic process of Pb / PbSO4 redox on the basis of diffusion, thereby effectively inhibiting irreversible sulfation.

[0017] The beneficial effects of the present invention are as follows: the negative electrode additive obtained by activating apricot shell activated carbon and performing potassium permanganate hydrothermal treatment has good compatibility with the negative electrode material, and the preparation method of the present invention can further improve the electron transmission capacity of the material on the basis of maintaining the original structure of the carbon material, and inhibit the sulfation and hydrogen evolution reaction of the lead-carbon battery; and the negative electrode additive has good stability in the battery reaction system, and has the advantages of high conductivity, high electrocatalytic activity, etc., which can improve the battery capacity and increase the cycle life of the lead-carbon battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the SEM image of the negative electrode additive prepared in Example 1.

[0019] Figure 2 This is the SEM image of the negative electrode additive prepared in Example 2.

[0020] Figure 3 This is the SEM image of the negative electrode additive prepared in Example 3.

[0021] Figure 4 This is a comparison chart of the cycle life of a blank electrode and the electrode prepared in Example 1.

[0022] Figure 5 This is a comparison chart of the cycle life of a blank electrode and the electrode prepared in Example 2.

[0023] Figure 6 This is a comparison chart of the cycle life of a blank electrode and the electrode prepared in Example 3.

[0024] Figure 7 This is a rate performance diagram of the battery composed of electrodes prepared in Example 1. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0026] All chemical reagents not specified in the examples and comparative examples of the present invention were commercially available analytically pure for the experiments.

[0027] Example 1

[0028] A method for preparing a negative electrode additive for inhibiting irreversible sulfation of a negative electrode comprises the following steps:

[0029] (1) First, the apricot shell activated carbon was vacuum dried at 60 ° C for 48 hours, and the potassium hydroxide activator was weighed, the mass of which was twice the mass of the apricot shell activated carbon powder, and the potassium hydroxide was made into a solution. Then, the dried apricot shell activated carbon powder was mixed with the KOH solution, and the apricot shell activated carbon powder was activated at 680 ° C for 2 hours. The apricot shell activated carbon powder was placed in an oven to dry, and the activated apricot shell activated carbon powder was crushed and soaked in 3 mol / L hydrochloric acid solution for 40 minutes. The hydrochloric acid solution was removed by filtration, and the powder was rinsed with deionized water until neutral, and dried in a drying oven at 110 ° C to obtain a carbon precursor.

[0030] (2) 1g carbon precursor and 80mL0.08mol·L -1 The KMnO4 solution was reacted and hydrothermally reacted at 100 °C for 3 h. The solid product was then filtered out, washed with deionized water and dried at 110 °C overnight to finally obtain the negative electrode additive.

[0031] The negative electrode additive prepared in Example 1 is added to the negative electrode material of a lead-carbon battery. The battery consists of two positive plates, one negative plate and an electrolyte.

[0032] The negative electrode plate is prepared as follows: First, lead oxide powder, conductive fiber (0.275 wt%, relative to 100 g of lead oxide powder), carbon black (1.325 wt%), lignin sulfonate (0.075 wt%), barium sulfate (0.75 wt%), and a negative electrode additive (1 wt%) are mixed and stirred until uniformly mixed. 17.5 ml of deionized water is then added while stirring. Sulfuric acid is then added dropwise to the mixture in small amounts and stirred repeatedly until a viscous paste forms. The lead paste is then evenly applied to a lead-calcium-tin alloy grid measuring 40.0 mm x 68.0 mm x 1.5 mm to form a negative electrode plate. The mass of the lead paste applied to the plate is 18.0 ± 0.2 g. The plate is then placed in a programmed constant temperature and humidity curing chamber for curing to obtain the negative electrode plate.

[0033] The positive electrode plate is prepared as follows: First, lead oxide powder, conductive fiber (0.275 wt%, relative to 100 g of lead oxide powder), carbon black (1.325 wt%), lignin sulfonate (0.075 wt%), and barium sulfate (0.75 wt%) are mixed. Then, 17.5 ml of deionized water is added while stirring. Subsequently, sulfuric acid is added dropwise to the mixture in small amounts and stirred repeatedly to form a viscous paste. The lead paste is then evenly applied to a lead-calcium-tin alloy grid measuring 40.0 mm × 68.0 mm × 1.5 mm to form a positive electrode plate. The mass of the lead paste applied to the plate is 18.0 ± 0.2 g. The plate is then placed in a programmed constant temperature and humidity curing chamber for curing to obtain the positive electrode plate.

[0034] A 2V / 4Ah battery consists of a negative plate (NAM, about 33.0g) and two positive plates (PAM, about 32.0g), separated by an AGM separator, which is 1.28g / ml -1 of sulfuric acid as the electrolyte.

[0035] The battery formation and performance tests were conducted on a battery tester (CT-4008T-5V6A-S1, Sunway). The program settings were: charge cut-off voltage 2.45V, discharge cut-off voltage 1.75V. The battery cycle life test conditions were: fully charge the battery at a 0.1C rate, then discharge to 50% state of charge, then charge at a 1C constant current for 30 seconds, rest for 5 seconds, discharge at a 1C constant current for 30 seconds, rest for 5 seconds, and repeat this cycle until the discharge voltage is below 1.75V, which is considered a battery failure. Figure 4 It can be seen that the cycle life of the lead-carbon battery in the embodiment reaches 15188 times, which is higher than 1744 times of the blank battery, wherein the blank battery is a lead-carbon battery without adding negative electrode additives.

[0036] according to Figure 7 The discharge specific capacity of the battery with composite material electrode-2 at different rates is higher than that of the blank battery. Especially at 1C rate, the discharge specific capacity of the composite material battery is 51.70mAh / g, which is 2.5 times that of the blank battery (19.99mAh / g).

[0037] Example 2

[0038] A method for preparing a negative electrode additive for inhibiting irreversible sulfation of a negative electrode comprises the following steps:

[0039] (1) First, the apricot shell activated carbon was vacuum dried at 60 ° C for 48 hours, and the potassium hydroxide activator was weighed, the mass of which was 1 times the mass of the apricot shell carbon powder, and the potassium hydroxide was made into a solution. Then, the dried apricot shell activated carbon powder was mixed with the KOH solution, and the apricot shell activated carbon powder was activated at 850 ° C for 2 hours. The apricot shell activated carbon powder was placed in an oven to dry, and the activated carbon material powder was crushed and soaked in 3 mol / L hydrochloric acid solution for 40 minutes. The hydrochloric acid solution was removed by filtration, and the powder was rinsed with deionized water until neutral, and dried in a drying oven at 110 ° C to obtain a carbon precursor.

[0040] (2) 1.5 g carbon precursor and 80 mL 0.08 mol·L -1 The KMnO4 solution was reacted and hydrothermally reacted at 150 °C for 0.5h. The solid product was then filtered out, washed with deionized water and dried at 110 °C overnight to finally obtain the negative electrode additive.

[0041] Similar to Example 1, the negative electrode additive prepared in Example 2 is added to the negative electrode material. Figure 5 It can be seen that the cycle life of the lead-carbon battery reaches 14,835 times, which is higher than the 1,744 times of the blank battery.

[0042] Example 3

[0043] A method for preparing a negative electrode additive for inhibiting irreversible sulfation of a negative electrode comprises the following steps:

[0044] (1) First, the apricot shell activated carbon was vacuum dried at 60 ° C for 48 hours, and the potassium hydroxide activator was weighed, the mass of which was 3 times the mass of the apricot shell activated carbon powder, and the potassium hydroxide was made into a solution. Then, the dried apricot shell activated carbon powder was mixed with the KOH solution, and the apricot shell activated carbon powder was activated at 700 ° C for 2 hours. The apricot shell activated carbon powder was placed in an oven to dry, and the activated carbon material powder was crushed and soaked in 3 mol / L hydrochloric acid solution for 40 minutes. The hydrochloric acid solution was removed by filtration, and the powder was rinsed with deionized water until neutral, and dried in a drying oven at 110 ° C to obtain a carbon precursor.

[0045] (2) 2 g of carbon precursor and 80 mL of 0.08 mol·L -1The KMnO4 solution was reacted and hydrothermally reacted at 150 °C for 2 h. The solid product was then filtered out, washed with deionized water and dried at 110 °C overnight to finally obtain the negative electrode additive.

[0046] Similar to Example 1, the negative electrode additive prepared in Example 3 was added to the negative electrode material. Figure 5 It can be seen that the cycle life of the lead-carbon battery reaches 14,425 times, which is higher than the 1,744 times of the blank battery.

[0047] The composite material structure prepared in Examples 1 to 3 of the present invention is as follows Figure 1-3 As shown in the figure, the composite material prepared by activation and hydrothermal treatment has a porous structure. When the mass ratio of KMnO4 to carbon precursor is 0.5:1, the porous structure of the material is still relatively obvious, indicating that the loading amount of manganese oxide is still relatively small; when the mass ratio is 2:1, manganese oxide agglomerates and is unevenly distributed; when the mass ratio is 1:1, manganese oxide is more evenly distributed and the porous structure is not completely closed.

[0048] Comparative Example 1

[0049] A method for preparing a negative electrode additive for inhibiting irreversible sulfation of a negative electrode comprises the following steps:

[0050] (1) First, the apricot shell activated carbon was vacuum dried at 60°C for 48 hours to obtain dried apricot shell activated carbon powder.

[0051] (2) 1g of dried apricot shell activated carbon powder was mixed with 80mL of 0.08mol·L -1 The KMnO4 solution was reacted and hydrothermally reacted at 100 °C for 3 h. The solid product was then filtered out, washed with deionized water and dried at 110 °C overnight to finally obtain the negative electrode additive.

[0052] Similar to Example 1, when the negative electrode additive prepared in Comparative Example 1 was added to the negative electrode material, the cycle life of the lead-carbon battery reached 5188 times, which was higher than that of the blank battery.

[0053] Comparative Example 3

[0054] A method for preparing a negative electrode additive for inhibiting irreversible sulfation of a negative electrode comprises the following steps:

[0055] (1) First, apricot shell activated carbon is vacuum dried at 60°C for 48h, and potassium hydroxide activator is weighed, the mass of which is 2 times the mass of apricot shell activated carbon powder. The potassium hydroxide is made into a solution, then the dried apricot shell activated carbon powder is mixed with the KOH solution, and after high-temperature activation at 680°C for 2h, the apricot shell activated carbon powder is placed in an oven for drying. The activated carbon material powder is crushed, soaked in a 3 mol / L hydrochloric acid solution for 40 min, the hydrochloric acid solution is removed by suction filtration, and then washed with deionized water until neutral. The mixture is dried in a drying oven at 110°C, thereby obtaining a carbon precursor.

[0056] (2) 1g of the carbon precursor is reacted with 80mL of a 0.08mol·L -1 of MnO2 solution at 100°C for 3h, then the solid product is filtered out, washed with deionized water and dried at 110°C overnight, and finally the negative electrode additive is obtained.

[0057] Similar to Example 1, the negative electrode additive prepared in Comparative Example 3 is added to the negative electrode material, and the cycle life of the lead-carbon battery reaches 7458 times, which is higher than that of the blank battery.

[0058] Comparative Example 4

[0059] A method for preparing a negative electrode additive for inhibiting negative electrode irreversible sulfation, comprising the following steps:

[0060] (1) First, apricot shell activated carbon is vacuum dried at 60°C for 48h, and potassium hydroxide activator is weighed, the mass of which is 2 times the mass of apricot shell activated carbon powder. The potassium hydroxide is made into a solution, then the dried apricot shell activated carbon powder is mixed with the KOH solution, and after high-temperature activation at 680°C for 2h, the apricot shell activated carbon powder is placed in an oven for drying. The activated carbon material powder is crushed, soaked in a 3 mol / L hydrochloric acid solution for 40 min, the hydrochloric acid solution is removed by suction filtration, and then washed with deionized water until neutral. The mixture is dried in a drying oven at 110°C, thereby obtaining a carbon precursor.

[0061] (2) 2g of the carbon precursor is added to 80mL of water, and hydrothermal reaction is carried out at 150°C for 3h, then the solid product is filtered out, washed with deionized water and dried at 110°C overnight, and finally the negative electrode additive is obtained.

[0062] Similar to Example 1, the negative electrode additive prepared in Comparative Example 4 is added to the negative electrode material, and the cycle life of the lead-carbon battery reaches 3139 times, which is higher than that of the blank battery.

[0063] Comparative Example 5

[0064] The negative electrode additive prepared in Comparative Example 4 was physically mixed with MnO2 in a mass ratio of 1:1 to prepare a negative electrode additive. Then, similar to Example 1, the negative electrode additive prepared in Comparative Example 5 was added as an additive to the negative electrode material. However, the lead-carbon battery suffered from severe sulfation and poor cycle performance, with a cycle life of 7458 times. At the same time, problems such as poor contact, uneven distribution, and insufficient interface reaction also occurred.

[0065] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A negative electrode additive used as an additive for lead-carbon battery negative electrode materials, characterized in that: The preparation method of the negative electrode additive comprises the following steps: (1) Drying the apricot shell activated carbon, placing the dried apricot shell activated carbon in a potassium hydroxide solution for high-temperature activation, and then drying to obtain activated apricot shell activated carbon, impregnating the activated apricot shell activated carbon with a hydrochloric acid solution, and then filtering, washing, and drying to obtain a carbon precursor; (2) The carbon precursor is placed in a potassium permanganate solution for hydrothermal reaction, and finally washed and dried to obtain a negative electrode additive.

2. The negative electrode additive according to claim 1 is used as an additive for lead-carbon battery negative electrode materials, characterized in that: The mass ratio of the potassium hydroxide to the apricot shell activated carbon is (1-3):

1.

3. The negative electrode additive according to claim 1 is used as an additive for lead-carbon battery negative electrode materials, characterized in that: The temperature of the high temperature activation is 650-850° C., and the time is 2 hours.

4. The negative electrode additive according to claim 1 is used as an additive for lead-carbon battery negative electrode materials, characterized in that: The concentration of the hydrochloric acid solution is 2-3 mol / L, and the immersion time is 30-40 min.

5. The negative electrode additive according to claim 1 is used as an additive for lead-carbon battery negative electrode materials, characterized in that: The concentration of the potassium permanganate solution is 0.04-0.16 mol / L, and the mass ratio of the carbon precursor to the potassium permanganate is 1:0.5-1:

2.

6. The negative electrode additive according to claim 1 is used as an additive for lead-carbon battery negative electrode materials, characterized in that: The temperature of the hydrothermal reaction is 100-150° C., and the time is 1-3 hours.

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