Negative electrode additive as well as preparation method and application thereof

Abstract

The invention discloses a negative electrode additive as well as a preparation method and application thereof, and belongs to the technical field of metal oxide / biomass carbon composite materials and lead-carbon batteries. The preparation method comprises the following steps: firstly, placing apricot shell carbon in a potassium hydroxide solution for high-temperature activation treatment, and then performing hydrothermal reaction with 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 the battery capacity and prolong the cycle life of the battery.

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 have the advantages of fast charging, long cycle life, high cost performance and high recovery rate, and have great development potential in the field of new energy storage. Lead-carbon batteries effectively suppress the sulfation problem of the negative electrode, but the process of lead sulfate conversion to metallic lead is not completely reversible. Under certain specific conditions, lead sulfate particles will accumulate on the surface of the negative electrode. Due to the accumulation of lead sulfate, the battery capacity will gradually lose during the subsequent discharge process. This phenomenon is called "hard sulfation". The most commonly used carbonaceous materials for additives to the negative active substances of lead-carbon batteries are: activated carbon, graphite, carbon black, graphene, various carbon nanomaterials and carbon composite materials.

[0003] The common carbon materials in the negative electrode of lead-carbon batteries mainly have the following mechanisms of action: increasing conductivity, double-layer capacitance, steric hindrance, increasing electrode specific surface area, electrocatalysis, etc. Although the introduction of carbon materials has alleviated the problem of sulfation, the effect of a single carbon material is single, and it has not achieved a significant increase in the battery cycle life. In addition, there is a serious problem of hydrogen evolution, so it is difficult to solve the problem comprehensively. 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 a preparation method and application thereof. 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 by 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) placing the carbon precursor in a potassium permanganate solution for hydrothermal reaction, and finally washing and drying 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 with the problems of low reaction activity, many by-products and strong corrosion in the activation of apricot shell activated carbon by calcium hydroxide or sodium hydroxide, potassium hydroxide can avoid the above problems, and within the range of "the mass ratio of potassium hydroxide to apricot shell activated carbon is (1-3): 1" defined in the present invention, the activation effect of apricot shell activated carbon is good, and a suitable microporous structure will be constructed without causing structural collapse. The activated apricot shell activated carbon combined with multivalent manganese oxide can inhibit the sulfation and hydrogen evolution reaction of 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 negative electrode materials of lead-carbon batteries.

[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 realizing effective inhibition of irreversible sulfation.

[0017] The beneficial effects of the present invention are as follows: the present invention activates apricot shell activated carbon and performs potassium permanganate hydrothermal treatment to obtain a negative electrode additive, which 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 with the electrode composition prepared in Example 1. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with 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 reagents for 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 is vacuum dried at 60°C for 48 hours, and a potassium hydroxide activator is weighed, the mass of which is twice the mass of the apricot shell activated carbon powder, and the potassium hydroxide is made into a solution, and then the dried apricot shell activated carbon powder is mixed with the KOH solution, and the apricot shell activated carbon powder is activated at 680°C for 2 hours and then placed in an oven to dry, and the activated apricot shell activated carbon powder is crushed and soaked in a 3 mol / L hydrochloric acid solution for 40 minutes, and the hydrochloric acid solution is removed by suction, and then rinsed with deionized water until neutral, and dried in a drying oven at 110°C, thereby obtaining a carbon precursor.

[0030] (2) 1 g of carbon precursor and 80 mL of 0.08 mol·L -1 The KMnO4 solution was reacted and hydrothermally reacted at 100 °C for 3 h, and then the solid product was 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 electrode plates, one negative electrode plate and an electrolyte.

[0032] The preparation method of the negative electrode plate is as follows: First, lead oxide powder, conductive fiber (0.275wt%, mass fraction relative to 100g lead oxide powder), carbon black (1.325wt%), lignin sulfonate (0.075wt%), barium sulfate (0.75wt%) and negative electrode additive (1wt%) are mixed and stirred evenly. Then, 17.5ml of deionized water is added while stirring; then, sulfuric acid is dripped into the mixture in small amounts and stirred several times to form a viscous paste. Then, the lead paste is evenly applied on a lead-calcium-tin alloy grid with a geometric area of ​​40.0mm×68.0mm×1.5mm to obtain a negative electrode plate, and the mass of the lead paste applied to the electrode plate is 18.0±0.2g. The electrode plate is placed in a constant temperature and humidity curing box set according to the program for curing to obtain a negative electrode plate.

[0033] The preparation method of the positive electrode plate is as follows: first, lead oxide powder, conductive fiber (0.275wt%, mass fraction relative to 100g lead oxide powder), carbon black (1.325wt%), lignin sulfonate (0.075wt%) and barium sulfate (0.75wt%) are mixed, and then 17.5ml of deionized water is added while stirring; then, sulfuric acid is dripped into the mixture in small amounts and stirred to form a viscous paste. Then, the lead paste is evenly applied on a lead-calcium-tin alloy grid with a geometric area of ​​40.0mm×68.0mm×1.5mm to obtain a positive electrode plate, and the mass of the lead paste applied to the electrode plate is 18.0±0.2g. The electrode plate is placed in a constant temperature and humidity curing box set according to the program for curing to obtain a 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, of which 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 1C constant current for 30s, leave for 5s, discharge at 1C constant current for 30s, leave for 5s, and so on until the discharge voltage is lower than 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 a 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, and then the dried apricot shell activated carbon powder was mixed with the KOH solution, and the apricot shell activated carbon powder was placed in an oven for drying after high-temperature activation at 850°C for 2 hours. The activated carbon material powder was crushed and soaked in a 3 mol / L hydrochloric acid solution for 40 minutes, the hydrochloric acid solution was removed by suction, 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 0.5 h, and then the solid product was 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 a 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, and then the dried apricot shell activated carbon powder was mixed with the KOH solution, and the apricot shell activated carbon powder was placed in an oven for drying after high-temperature activation at 700°C for 2 hours. The activated carbon material powder was crushed and soaked in a 3 mol / L hydrochloric acid solution for 40 minutes, the hydrochloric acid solution was removed by suction, and the powder was rinsed with deionized water until neutral, and then 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, and then the solid product was 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 is added to the negative electrode material. Figure 5 It can be seen that the cycle life of the lead-carbon battery reaches 14425 times, which is higher than the 1744 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; 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 distributed more evenly 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) 1 g of dried apricot shell activated carbon powder was mixed with 80 mL of 0.08 mol·L -1 The KMnO4 solution was reacted and hydrothermally reacted at 100 °C for 3 h, and then the solid product was filtered out, washed with deionized water and dried at 110 °C overnight to finally obtain the negative electrode additive.

[0052] Similar to Example 1, the negative electrode additive prepared in Comparative Example 1 was added to the negative electrode material, and 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, the apricot shell activated carbon is vacuum dried at 60°C for 48 hours, and a potassium hydroxide activator is weighed, the mass of which is twice the mass of the apricot shell activated carbon powder, and the potassium hydroxide is made into a solution, and then the dried apricot shell activated carbon powder is mixed with the KOH solution, and the apricot shell activated carbon powder is activated at 680°C for 2 hours and then placed in an oven to dry, and the activated carbon material powder is crushed and soaked in a 3 mol / L hydrochloric acid solution for 40 minutes, and the hydrochloric acid solution is removed by suction, and then rinsed with deionized water until neutral, and dried in a drying oven at 110°C to obtain a carbon precursor.

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

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

[0058] Comparative Example 4

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

[0060] (1) First, the apricot shell activated carbon is vacuum dried at 60°C for 48 hours, and a potassium hydroxide activator is weighed, the mass of which is twice the mass of the apricot shell activated carbon powder, and the potassium hydroxide is made into a solution, and then the dried apricot shell activated carbon powder is mixed with the KOH solution, and the apricot shell activated carbon powder is activated at 680°C for 2 hours and then placed in an oven to dry, and the activated carbon material powder is crushed and soaked in a 3 mol / L hydrochloric acid solution for 40 minutes, and the hydrochloric acid solution is removed by suction, and then rinsed with deionized water until neutral, and dried in a drying oven at 110°C to obtain a carbon precursor.

[0061] (2) 2 g of carbon precursor was added to 80 mL of water and hydrothermally reacted at 150 °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.

[0062] Similar to Example 1, the negative electrode additive prepared in Comparative Example 4 was added to the negative electrode material, and the cycle life of the lead-carbon battery reached 3139 times, which was 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, and 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 had serious sulfation and poor cycle performance. The cycle life reached 7458 times. At the same time, there were problems such as poor contact, uneven distribution, and insufficient interface reaction.

[0065] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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 method for preparing a negative electrode additive, characterized in that: The following steps are involved: (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) placing the carbon precursor in a potassium permanganate solution for hydrothermal reaction, and finally washing and drying to obtain a negative electrode additive.

2. The method for preparing the negative electrode additive according to claim 1, characterized in that: The mass ratio of potassium hydroxide to apricot shell activated carbon is (1-3):

1.

3. The method for preparing the negative electrode additive according to claim 1, characterized in that: The temperature of the high temperature activation is 650-850° C. and the time is 2 hours.

4. The method for preparing the negative electrode additive according to claim 1, 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 method for preparing the negative electrode additive according to claim 1, 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 method for preparing the negative electrode additive according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 100-150° C., and the time is 1-3 hours.

7. The negative electrode additive prepared according to the method for preparing the negative electrode additive according to any one of claims 1 to 6.

8. The negative electrode additive according to claim 7 is used as an additive for negative electrode materials of lead-carbon batteries.

Images