A positive plate and a preparation method and application thereof

Abstract

The application relates to the technical field of lead-acid batteries, and particularly discloses a positive plate and a preparation method and application thereof. The positive plate provided by the application comprises the following raw material components: modified PbO2, PbS and carbon fibers; wherein the modified PbO2 is PbO2 wrapped by PbF2. The modification of PbO2 enables the surface of PbO2 to be wrapped by PbF2, which can obviously avoid the problem of excessive sulfation of PbO2 in the repeated charging process; the PbF2 wrapped on the surface of PbO2 can also enable PbO2 to be tightly combined with the metal bond in PbS through F chemical bonds, so that PbO2 is uniformly dispersed between PbS layers; the chemical bonds in the carbon fibers can also be tightly connected with the chemical bonds in PbS, so that the prepared positive plate becomes a tightly connected whole, the three raw material components synergistically act, and the cycle life, energy density and rate performance of the battery are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lead-acid batteries, in particular to a positive plate and a preparation method and application thereof. BACKGROUND

[0002] Due to the low price of lead, lead-acid batteries are widely used in many fields such as transportation, communication, power and military, but there are some problems in the use of lead-acid batteries, such as low energy density, only one third of lithium batteries. The active material content in the positive plate of the lead-acid battery is an important parameter to determine the energy density of the battery. At present, the commonly used method for preparing the positive plate is as follows: first, prepare lead paste and metal plate grid, then evenly apply the lead paste on the plate grid, and then solidify, form, clean and dry, and finally cut to the appropriate size. In the above operation, the actual solid content of PbO2 in the positive plate is less than 80%, which limits the improvement of the energy density of the positive plate of the lead-acid battery. However, if the content of PbO2 is increased during the production of the positive plate, the strength of the positive plate will be reduced, thereby causing a serious decrease in the cycle performance. In addition, the cycle life of the lead-acid battery is also relatively short, only about 300-500 times, which is due to the excessive sulfation of the positive material (PbSO4 size increases and activity decreases) during use or charge-discharge cycle, resulting in a significant decrease in capacity and a decrease in cycle performance. In view of the problems of low energy density, short cycle life and poor rate performance of the existing positive plate of the lead-acid battery, it is urgent to provide a new positive plate and a preparation method thereof. SUMMARY

[0003] In view of the problems of low energy density, short cycle life and poor rate performance of the existing positive plate, the present application provides a positive plate and a preparation method and application thereof.

[0004] To solve the above technical problems, the technical scheme provided by the present application is:

[0005] The first aspect of the present application provides a positive plate comprising the following raw material components: modified PbO2, PbS and carbon fiber.

[0006] The modified PbO2 is PbF2-coated PbO2.

[0007] In order to improve the low rate performance of the existing positive plate of lead-acid battery, researchers have selected graphene or foam metal as the conductive framework of the positive plate to replace the traditional metal grid, but the inventor found in the research process that when graphene is used as the conductive framework, the interface bonding force between graphene and lead active material is poor, thereby greatly affecting the conductivity of the positive plate and the service life of the battery, and the cost of graphene is high, which is difficult to mass produce; when foam metal is used as the conductive framework, the density of the foam metal is high, and the material cost is high, the use of foam metal not only increases the weight of the battery, but also increases the production cost of the lead-acid battery, and the foam metal may be corroded in the electrolyte, affecting the service life of the battery. Therefore, it is of great significance to provide a new positive plate and a preparation method thereof.

[0008] Compared with the prior art, in the positive plate provided by the application, the surface of PbO2 is coated with PbF2 by modification, which can obviously avoid the problem of excessive sulfation of PbO2 during repeated charging, thereby improving the cycle performance of the positive plate applied to the battery; the PbF2 coated on the surface of PbO2 can also make PbO2 tightly combined with the metal bond in PbS through F chemical bond, so that PbO2 is uniformly dispersed between the PbS layers, so that the prepared positive plate can also form a high-strength whole without the aid of a metal grid, thereby being beneficial to improving the energy density, rate performance and service life of the battery; the interaction force between PbS can form a two-dimensional grid structure that is interlaced with each other, further ensuring that PbO2 is uniformly distributed in the positive plate, thereby improving the rate performance of the battery by reducing the internal resistance of the battery, and the uniformly distributed PbO2 can further ensure that the battery has high energy density and excellent cycle performance; further, the application also adds carbon fibers to the positive plate, which can further reduce the resistance of the positive plate and improve the rate performance of the battery, and the chemical bond in the carbon fibers can also be tightly connected with the chemical bond in PbS, so that the prepared positive plate becomes a tightly connected whole, greatly improving the cycle life of the battery.

[0009] Preferably, the mass ratio of the modified PbO2, PbS and carbon fibers is 100: (2-10): 1.

[0010] The application can make the three substances synergistically exert the maximum advantage by limiting the ratio of the modified PbO2, PbS and carbon fibers, thereby greatly improving the energy density, rate performance and cycle service life of the battery.

[0011] Preferably, the diameter of the carbon fibers is 6-8 mu m, and the conductivity coefficient is 700-900 S / m.

[0012] Preferably, the preparation method of the modified PbO2 comprises the following steps: mixing PbO2 and hydrofluoric acid uniformly, reacting at 60-80 DEG C, washing, solid-liquid separation, drying, and obtaining the modified PbO2.

[0013] The preparation method of the modified PbO2 provided by the application is simple in operation, can prepare PbO2 wrapped with PbF2 on the surface, can obviously avoid the problem of excessive sulfation of PbO2 in repeated charging process, and can greatly improve the energy density, rate performance and cycle life of the battery when applied to the positive plate.

[0014] Preferably, the molar ratio of the PbO2 to the hydrofluoric acid is (5-20):1.

[0015] By limiting the ratio of the PbO2 to the hydrofluoric acid, the modified PbO2 prepared can have a specific structure, and the energy density, rate performance and cycle of the battery can be improved.

[0016] Preferably, the reaction time is 1-5 h.

[0017] Preferably, the drying temperature is <100 DEG C.

[0018] The second aspect of the application provides a preparation method of the positive plate, comprising the following steps:

[0019] S1, weighing each raw material component according to the proportion, dispersing the PbS in water to obtain a PbS dispersion liquid;

[0020] S2, mixing the modified PbO2, carbon fiber and PbS dispersion liquid uniformly, and drying at -45 DEG C to -35 DEG C to obtain a positive plate composite material;

[0021] S3, hot pressing the positive plate composite material to obtain the positive plate.

[0022] Compared with the prior art, in the preparation method of the positive plate provided by the application, the modified PbO2, carbon fiber and PbS dispersion liquid are freeze-dried in S2, the mixed liquid has no stratification phenomenon during drying, the modified PbO2 can be uniformly distributed in the interior of the PbS, and the energy density, rate performance and cycle of the battery can be improved; the positive plate composite material is further hot pressed, which can not only promote the chemical bonding between the modified PbO2 and the PbS, but also can ensure that the PbS and the carbon fiber are chemically bonded to form a compact whole, greatly improving the energy density and cycle performance of the battery, and the battery resistance can be further reduced by using the preparation method of the positive plate provided by the application, so as to improve the rate performance of the battery.

[0023] Preferably, in S1, the concentration of the PbS dispersion liquid is 0.05-0.1 mol / L.

[0024] Preferably, in S2, the drying condition is that the positive plate composite is free of moisture.

[0025] Preferably, in S3, the hot-pressing condition is that the pressure is 30-80 MPa and the temperature is 100-200℃.

[0026] The preferable high-temperature and high-pressure condition can further improve the binding force between PbS and carbon fiber and modified PbO2, thereby improving the energy density, cycle performance and rate performance of the battery.

[0027] Preferably, in S3, the hot-pressing time is 0.5-3 h.

[0028] The second aspect of the application provides the use of the above positive plate or the positive plate prepared by the above preparation method in a lead-acid battery.

[0029] The positive plate provided by the application can significantly improve the rate performance, cycle performance and energy density of the lead-acid battery. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.

[0031] Example 1

[0032] The example provides a positive plate comprising the following raw material components: modified PbO2, PbS and carbon fiber.

[0033] The modified PbO2 is PbF2-coated PbO2; the mass ratio of the modified PbO2, PbS and carbon fiber is 100:10:1; the diameter of the carbon fiber is 6 μm and the conductivity coefficient is 700 S / m.

[0034] The preparation method of the modified PbO2 comprises the following steps: uniformly mixing 5 mol PbO2 and 1 mol hydrofluoric acid, reacting at 80℃ for 1 h, washing, solid-liquid separation and controlling the drying temperature <100℃ to obtain the modified PbO2.

[0035] The example also provides a preparation method of the above positive plate, comprising the following steps:

[0036] S1, the raw material components are weighed according to the ratio, the PbS is dispersed in water to obtain a PbS dispersion liquid with a concentration of 0.05 mol / L;

[0037] S2, the modified PbO2, carbon fiber and PbS dispersion liquid are mixed uniformly, and dried at -35℃ to obtain a positive plate composite material;

[0038] S3, the positive plate composite material is hot pressed to obtain a positive plate; wherein the pressure of hot pressing is 30MPa, the temperature of hot pressing is 200℃, and the time of hot pressing is 0.5h.

[0039] Example 2

[0040] The embodiment provides a positive plate, which comprises the following raw material components: modified PbO2, PbS and carbon fiber.

[0041] The modified PbO2 is PbF2-coated PbO2; wherein the mass ratio of the modified PbO2, PbS and carbon fiber is 100:2:1, the diameter of the carbon fiber is 8μm, and the conductivity coefficient of the carbon fiber is 900S / m.

[0042] The preparation method of the modified PbO2 comprises the following steps: uniformly mixing 20mol PbO2 and 1mol hydrofluoric acid, reacting at 60℃ for 1h, washing, solid-liquid separation, and controlling the drying temperature to be <100℃ to obtain the modified PbO2.

[0043] The embodiment also provides a preparation method of the positive plate, which comprises the following steps:

[0044] S1, the raw material components are weighed according to the proportion, and PbS is dispersed in water to obtain a PbS dispersion liquid with a concentration of 0.1mol / L;

[0045] S2, the modified PbO2, carbon fiber and PbS dispersion liquid are mixed uniformly, and dried at -45℃ to obtain a positive plate composite material;

[0046] S3, the positive plate composite material is hot pressed to obtain a positive plate; wherein the pressure of hot pressing is 80MPa, the temperature of hot pressing is 100℃, and the time of hot pressing is 3h.

[0047] Example 3

[0048] The embodiment provides a positive plate, which comprises the following raw material components: modified PbO2, PbS and carbon fiber.

[0049] The modified PbO2 is PbF2-coated PbO2; wherein the mass ratio of the modified PbO2, PbS and carbon fiber is 100:6:1, the diameter of the carbon fiber is 7μm, and the conductivity coefficient of the carbon fiber is 800S / m.

[0050] The preparation method of the modified PbO2 includes the following steps: uniformly mixing 10 mol of PbO2 and 1 mol of hydrofluoric acid, reacting at 70 DEG C for 3 h, washing, solid-liquid separation, and controlling the drying temperature to be less than 100 DEG C, to obtain the modified PbO2.

[0051] The embodiment also provides a preparation method of the positive plate, including the following steps:

[0052] S1, weighing each raw material component according to the proportion, dispersing PbS in water to obtain a PbS dispersion liquid with a concentration of 0.07 mol / L;

[0053] S2, uniformly mixing the modified PbO2, carbon fibers and the PbS dispersion liquid, and drying at-40 DEG C to obtain a positive plate composite material;

[0054] S3, hot pressing the positive plate composite material to obtain the positive plate; wherein the pressure of hot pressing is 50 MPa, the temperature of hot pressing is 130 DEG C, and the time of hot pressing is 1 h.

[0055] Comparative Example 1

[0056] The comparative example provides a positive plate, which is different from the example 1 in that the PbS in the example 1 is replaced by an equal amount of MoS2, and the specific preparation method of the positive plate includes the following steps:

[0057] S1, weighing each raw material component according to the proportion, dispersing MoS2 in water to obtain a MoS2 dispersion liquid with a concentration of 0.05 mol / L;

[0058] S2, uniformly mixing the modified PbO2, carbon fibers and the MoS2 dispersion liquid, and drying at-35 DEG C to obtain a positive plate composite material;

[0059] S3, hot pressing the positive plate composite material to obtain the positive plate; wherein the pressure of hot pressing is 30 MPa, the temperature of hot pressing is 200 DEG C, and the time of hot pressing is 0.5 h.

[0060] The other components and steps are the same as those in the example 1.

[0061] Comparative Example 2

[0062] The comparative example provides a positive plate, which is different from the example 1 in that the modified PbO2 is PbO2 wrapped by PbCl2;

[0063] The preparation method of the modified PbO2 includes the following steps: uniformly mixing 5 mol of PbO2 and 0.1 mol of hydrochloric acid, reacting at 80 DEG C for 1 h, washing, solid-liquid separation, and controlling the drying temperature to be less than 100 DEG C, to obtain the modified PbO2;

[0064] Other ingredients and steps are the same as those of Example 1.

[0065] Comparative Example 3

[0066] This comparative example provides a positive plate, which is different from Example 1 in that the carbon fiber in Example 1 is replaced by polyaniline fiber.

[0067] Other ingredients and steps are the same as those of Example 1.

[0068] Comparative Example 4

[0069] This comparative example provides a positive plate, which is different from Example 1 in that the PbS in Example 1 is replaced by an equal amount of SnS.

[0070] Other ingredients and steps are the same as those of Example 1.

[0071] Comparative Example 5

[0072] This comparative example prepares a positive plate, which is a positive plate of the prior art containing a metal grid, and the preparation method specifically comprises the following steps: mixing lead dioxide powder, carbon black, polypropylene short fibers, water and sulfuric acid in a mass ratio of 80:1:0.5:9:9.5 to form an electrode paste. The electrode paste is uniformly coated on a lead-antimony alloy metal grid to form an electrode plate with a thickness of 2.5 mm. The coated electrode plate is dried at a temperature of 150℃ to remove moisture and solvent, so that the electrode plate becomes hard.

[0073] The electrochemical performance of the positive plates prepared in Examples 1-3 and Comparative Examples 1-5 is determined according to the present application, and the test method is as follows:

[0074] The positive plates prepared in Examples 1-3 and Comparative Examples 1-5 are cut into 20cm x 20cm with a thickness of 2.5mm±0.2mm, and 1.3mol / L sulfuric acid is used as an electrolyte solution to assemble a lead-acid full cell with a negative plate, which is denoted as lead-acid batteries I~III and lead-acid batteries comparative I~V, respectively. The energy density, internal resistance and cycle capacity retention rate of different lead-acid batteries are determined, and the results are shown in Table 1.

[0075] The preparation method of the negative plate is as follows: lead powder, carbon black, short fibers, water, sulfuric acid are mixed in a mass ratio of 80:1:0.5:9:9.5 to form an electrode paste. The electrode paste is uniformly coated on a metal grid to form an electrode plate with a thickness of 2.5mm. The coated electrode plate is dried at a temperature of 150℃ to remove moisture and solvent, so that the electrode plate becomes hard, and a negative plate of 20cm x 20cm is prepared.

[0076] The battery energy density test method is as follows: a blue light test system is used, and the discharge energy density is obtained by discharging at a current of 10mA to 1.5V at 25℃.

[0077] Battery internal resistance measurement method: direct reading using a battery internal resistance tester.

[0078] Cycle capacity retention rate: using a blue electric test system, in an environment of 25 DEG C, in the range of 1.5V~2.5V, using a current of 10mA, constant current charging and discharging 200 times, using the capacity of the 200th time divided by the first capacity to obtain the 200 cycle capacity retention rate.

[0079] Table 1

[0080]

[0081] From the data in Table 1, compared with the conventional positive plate prepared lead-acid battery relying on the metal grid, the lead-acid battery prepared using the positive plate provided by embodiments 1~3 has more excellent energy density and smaller internal resistance, and the 200 cycle capacity retention rate is also significantly improved.

[0082] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A positive plate characterized by, The raw material components comprise modified PbO2, PbS and carbon fiber; The modified PbO2 is PbF2-coated PbO2. The preparation method of the modified PbO2 comprises the following steps: uniformly mixing PbO2 and hydrofluoric acid, reacting at 60-80 DEG C, washing, solid-liquid separation, and drying to obtain the modified PbO2.

2. The positive plate of claim 1 wherein The mass ratio of the modified PbO2, PbS and carbon fiber is 100:(2-10):

1.

3. The positive plate of claim 1 or 2, wherein The diameter of the carbon fiber is 6-8 μm, and the conductivity coefficient is 700-900 S / m.

4. The positive plate of claim 1 wherein The molar ratio of the PbO2 and hydrofluoric acid is (5-20):

1.

5. The positive plate of claim 1 wherein The reaction time is 1-5 h.

6. A method of producing the positive plate according to any one of claims 1 to 5, characterized by, The method comprises the following steps: S1, taking each raw material component according to the proportion, dispersing the PbS in water to obtain a PbS dispersion liquid; S2, uniformly mixing the modified PbO2, carbon fiber and PbS dispersion liquid, drying at -45 DEG C to -35 DEG C to obtain a positive plate composite material; S3, hot pressing the positive plate composite material to obtain a positive plate.

7. The method for preparing the positive electrode plate as described in claim 6, characterized in that, In S1, the concentration of the PbS dispersion liquid is 0.05-0.1 mol / L; and / or In S3, the hot pressing condition is: the pressure is 30-80 MPa, and the temperature is 100-200 DEG C; and / or In S3, the hot pressing time is 0.5-3 h.

8. Application of the positive plate of any one of claims 1-5 or the positive plate prepared by the preparation method of any one of claims 6-7 in a lead-acid battery.

Images