Precipitation method for preparing high-oil-absorption-value high-specific-surface-area silicon dioxide for storage battery
阅读说明：本技术 沉淀法制备高吸油值高比表面积的蓄电池用二氧化硅 (Precipitation method for preparing high-oil-absorption-value high-specific-surface-area silicon dioxide for storage battery ) 是由 马逸敏 谭昊存 梁少彬 张文证 曹晓庆 于 2021-08-27 设计创作，主要内容包括：本发明属于无机非金属材料技术领域,具体涉及一种具有高吸油值高ASA比表面积的蓄电池PE隔板用二氧化硅的制备方法。本发明采取两步法进行制备二氧化硅,通过改变反应过程中的工艺条件,反应物质的浓度,反应时间、温度、压强等多种条件,有效提高了二氧化硅的产量,得到的二氧化硅具备高吸油高比表面积,具有高分散性的同时亦兼具相当的亲水性,实用性好,适合应用于蓄电池PE隔板中。(The invention belongs to the technical field of inorganic non-metallic materials, and particularly relates to a preparation method of silicon dioxide with a high oil absorption value and a high ASA specific surface area for a PE separator of a storage battery. According to the invention, the silicon dioxide is prepared by adopting a two-step method, the yield of the silicon dioxide is effectively improved by changing various conditions such as process conditions, concentration of reaction substances, reaction time, temperature, pressure and the like in the reaction process, and the obtained silicon dioxide has high oil absorption, high specific surface area, high dispersibility, considerable hydrophilicity and good practicability, and is suitable for being applied to the PE partition plate of the storage battery.)
1. A precipitation method for preparing high-oil-absorption-value high-specific-surface-area silicon dioxide for a storage battery is characterized by comprising the following preparation steps:
s1, adding a sodium sulfate solution into a reaction tank, and then adding 1-2 m3Heating the sodium silicate aqueous solution to 60-80 ℃, and keeping the pressure in the tank body at 0.3-0.5 MPa;
s2, dropwise adding a sulfuric acid solution into the reaction tank under stirring, adjusting the pH value in the reaction tank to 9-11, stopping adding acid, keeping the pressure and temperature in the tank unchanged, and aging the obtained seed crystal for 30-90 minutes;
s3, adding water to dilute the aged seed crystal obtained in the step S2, heating the temperature in a reaction tank to 80-90 ℃, keeping the pressure unchanged, and then simultaneously dropwise adding a sodium silicate aqueous solution and a sulfuric acid solution to keep the pH value in the tank at 9-11 until 22-27 m of the sodium silicate aqueous solution and the sulfuric acid solution are added3Stopping adding alkali after the sodium silicate aqueous solution is added;
s4, continuing to maintain the pressure, temperature and stirring frequency in the system in the step S3, adding a sulfuric acid solution with the concentration of 3.5-4 mol/L, stopping adding acid when the pH value of the reaction end point is controlled to be 3-5, and continuing to stir for 20-40 minutes;
s5, performing filter pressing and washing on the silicon dioxide obtained in the step S4, drying by adopting intensified airflow, removing moisture in materials, and crushing to obtain the silicon dioxide for the storage battery.
2. The precipitation method for preparing high oil absorption value high specific surface area silica for storage battery according to claim 1, wherein the method comprisesIn the step S1, the mass percent concentration of the sodium sulfate solution is 0.2-0.6 wt.%, and the addition amount of the sodium sulfate solution is 30-35 m3。
3. The method for preparing the silica for the storage battery with high oil absorption value and high specific surface area by the precipitation method according to claim 1, wherein the concentration of the sodium silicate aqueous solution in the steps S1 and S3 is 2-2.5 mol/L.
4. The method for preparing silica for a storage battery with high oil absorption value and high specific surface area by precipitation according to claim 1, wherein the aged seed crystal obtained in the step S2 is diluted by water in the step S3, and the addition amount of the water is 1-3 m3。
5. The method for preparing the silica for the storage battery with high oil absorption value and high specific surface area by the precipitation method according to claim 1, wherein the stirring frequency in the steps S2, S3 and S4 is 10-50 Hz.
6. The method for preparing the silica for the storage battery with high oil absorption value and high specific surface area by the precipitation method according to claim 1, wherein in the step S2, the concentration of the sulfuric acid solution is 3-4 mol/L, and the dropping speed of the sulfuric acid solution is 4-6 m3/h。
7. The method for preparing the silica for the storage battery with high oil absorption value and high specific surface area by the precipitation method according to claim 1, wherein the dropping speed of the sodium silicate aqueous solution in the step S3 is 25-30 m3/h。
8. The method for preparing the silica for the storage battery with high oil absorption value and high specific surface area by the precipitation method according to claim 1, wherein the concentration of the sulfuric acid solution in the step S3 is 7-8 mol/L, and the dropping speed of the sulfuric acid solution is 5-6 m3/h。
9. The method for preparing the silica for the storage battery with high oil absorption value and high specific surface area by the precipitation method according to claim 1, wherein the crushed particle size of the silica obtained in the step S5 is 10-20 μm.
10. The application of the silicon dioxide for the storage battery, which is prepared by the precipitation method according to any one of claims 1 to 9 and has a high oil absorption value and a high specific surface area, in the preparation of a PE separator of the storage battery.
Technical Field
The invention belongs to the technical field of inorganic non-metallic materials, and particularly relates to a preparation method and application of silicon dioxide with high oil absorption value and high specific surface area.
Background
The separator is an important component in the storage battery, and is arranged between a positive plate and a negative plate of the storage battery, and the quality of the separator directly influences the discharge capacity and the charge-discharge cycle service life of the storage battery. The separator has the following functions in the storage battery, and firstly, the separator prevents the positive and negative plates from contacting with each other to cause the internal short circuit of the battery; secondly, the pole plate has certain strength to bear the variable force caused by the deformation and bending of the pole plate and the falling of the active substance; and thirdly, a certain amount of electrolyte can be stored in the separator to ensure the reaction requirement of the battery.
PE separators for lead storage batteries have been produced industrially since the 70's in the 20 th century for nearly 30 years. In the 30 years, the PE separator has been rapidly developed due to its advantages of small pore diameter, small resistance, high mechanical strength, capability of bag making, and the like. The PE clapboard is composed of main materials (ultra-high molecular weight Polyethylene (PE), silicon dioxide and process oil) and additives (carbon black, antioxidant and the like), is more precise and complex in manufacturing process, and integrates chemical industry, machinery and electronics.
In PE separators, silica serves as a framework, accounting for about 60% of the total separator weight, and the porous silica provides for the high porosity of the PE separator. Under normal temperature and normal pressure, the silicon dioxide has stable physical and chemical properties, the silicon dioxide provides a pore channel in the separator, the larger the particle is, the higher the oil absorption value is, the larger the pore diameter is, the higher the porosity is, and the preparation of the separator is facilitated. Meanwhile, the interaction between mesopores and macropores distributed in the silicon dioxide aggregate and the polymer is stronger than that of micropores, and the higher ASA specific surface area means larger mesopore and macropore specific surface area, so that the wettability of the PE separator in sulfuric acid can be improved, a hydrophilic effect is provided, and the electrical property of the separator is improved. At present, most of silicon dioxide used by the PE separator is precipitation amorphous silicon dioxide, the production process generally has the problems of complex operation, large gel amount and low yield, and the prepared silicon dioxide for the PE separator also has the problems of higher or lower specific surface area, low oil absorption value and the like.
Chinese patent application CN101597065A discloses a preparation method of white carbon black for PE partition boards, which comprises the steps of heating partial water glass to 84-87 ℃, carrying out acid addition reaction for 30-40 min, adding water glass and sulfuric acid simultaneously when the pH value of a suspension reaches 10-10.7, keeping the pH value of the suspension unchanged, adding all the rest water glass within 40-55 min, continuing adding sulfuric acid within 10-25 min until the water glass completely reacts, adjusting the pH value of the suspension to 6.0 with acid, and carrying out aging, filtering, washing, slurrying and drying to obtain the white carbon black. However, the specific surface area and DBP absorption value of the silica prepared by the method are low, gel is easily generated in the preparation process, the yield is low, and the gel amount in the silica product influences the acid weight loss of the PE separator, so that the dimensional stability and the service life are influenced.
Therefore, it is needed to prepare silica with high oil absorption value and high ASA specific surface area, which can effectively improve the yield of silica, make the obtained silica have the properties of high oil absorption value and high specific surface area, and be applied to a PE separator of a storage battery to directly influence the porosity, resistance, dimensional stability, impurity content and the like of the PE separator.
Disclosure of Invention
In order to solve the problems in the prior art, the invention aims to provide a preparation method and application of silica with high oil absorption value and ASA specific surface area.
The technical scheme of the invention is as follows:
a precipitation method for preparing high-oil-absorption-value high-specific-surface-area silicon dioxide for a storage battery comprises the following preparation steps:
s1, adding a sodium sulfate solution into a reaction tank, and then adding 1-2 m3Heating the sodium silicate aqueous solution to 60-80 ℃, and keeping the pressure in the tank body at 0.3-0.5 MPa;
s2, dropwise adding a sulfuric acid solution into the reaction tank under stirring, adjusting the pH value in the reaction tank to 9-11, stopping adding acid, keeping the pressure and temperature in the tank unchanged, and aging the obtained seed crystal for 30-90 minutes;
s3, diluting the aged seed crystal obtained in the step S2 with water, and heating the inside of the reaction tank to 80 DEGAt the temperature of 90 ℃ below zero, the pressure is unchanged, then the sodium silicate aqueous solution and the sulfuric acid solution are simultaneously dripped, the pH value in the tank is kept at 9-11 until 22-27 m is added3Stopping adding alkali after the sodium silicate aqueous solution is added;
s4, continuing to maintain the pressure, temperature and stirring frequency in the system in the step S3, adding a sulfuric acid solution with the concentration of 3.5-4 mol/L, stopping adding acid when the pH value of the reaction end point is controlled to be 3-5, and continuing to stir for 20-40 minutes;
s5, performing filter pressing and washing on the silicon dioxide obtained in the step S4, removing moisture in the materials by adopting an enhanced airflow drying technology, and crushing to obtain the silicon dioxide.
Further, the mass percent concentration of the sodium sulfate solution in the step S1 is 0.2-0.6 wt.%, and the addition amount of the sodium sulfate solution is 30-35 m3。
Further, the concentration of the sodium silicate aqueous solution in the steps S1 and S3 is 2-2.5 mol/L.
Further, in the step S3, the aged seed crystal obtained in the step S2 is diluted with water, and the amount of the added water is 1-3 m3。
Further, the stirring frequency in the steps S2, S3 and S4 is 10-50 Hz.
Further, in step S2, the concentration of the sulfuric acid solution is 3-4 mol/L, and the dropping speed of the sulfuric acid solution is 4-6 m3/h。
Further, the dropping speed of the sodium silicate aqueous solution in the step S3 is 25-30 m3/h
Further, the concentration of the sulfuric acid solution in the step S3 is 7-8 mol/L, and the dropping speed of the sulfuric acid solution is 5-6 m3/h。
Further, the crushed particle size of the silicon dioxide obtained in the step S5 is 10-20 μm.
In addition, the invention also provides application of the silicon dioxide for the storage battery, which is prepared by the precipitation method and has high oil absorption value and high specific surface area, in preparing the PE separator of the storage battery.
In the preparation method provided by the invention, the silicon dioxide is prepared by adopting a two-step method, the yield of the silicon dioxide is effectively improved by changing various conditions such as process conditions, concentration of reaction substances, reaction time, temperature, pressure and the like in the reaction process, the obtained silicon dioxide has high oil absorption and high specific surface, has high dispersibility, also has equivalent hydrophilicity and good practicability, is applied to the PE partition plate of the storage battery, has high porosity which is more than 80 percent, has small acid weight loss and small resistance, can improve the long-term stability of the prepared PE partition plate, and effectively prolongs the service life of the storage battery.
Firstly, adopting an acid-dropping-alkali strategy in the first step and the second step, carrying out a pressure reaction under an alkaline condition, controlling the pressure in the reaction process, reducing the concentration of a sodium sulfate solution and increasing the using amount of the sodium sulfate solution, controlling the concentration of sodium sulfate in the solution to be in a proper range, preventing the silica gel from generating too fast in the initial stage, increasing the using amount of the sodium sulfate solution, and generating silica at a fast speed in a long time, so that the BET specific surface area and the oil absorption value of a finished silica product can be effectively improved; meanwhile, the pH value in the reaction process is increased so as to be beneficial to improving the oil absorption value of the silicon dioxide; finally, the pH value of the end point of the reaction is controlled, which is beneficial to controlling the specific surface area; fifthly, pressure filtration washing is carried out to reduce the salt content of the silicon dioxide to be less than or equal to 0.5 percent; sixthly, drying and crushing the materials by adopting an enhanced airflow drying technology, wherein the particle size of the finally obtained silicon dioxide is 10-20 mu m, and experiments prove that the silicon dioxide prepared by adopting the preparation process disclosed by the invention has an oil absorption value of 285-296 ml/100g, a moderate specific surface area of 158-162 m2Between/g.
Compared with the prior art, the silicon dioxide for the PE separator of the storage battery provided by the invention has the following advantages:
(1) according to the preparation method of the silicon dioxide for the PE partition board of the storage battery, provided by the invention, an alkaline system reaction is adopted, a two-step method is combined, the pH value in the reaction process is controlled at a higher level, the silicon dioxide with a high oil absorption value and a higher specific surface area is prepared, and experiments prove that the silicon dioxide prepared by the preparation process has the oil absorption value of 285-296 ml/100g, the specific surface area is moderate, and the oil absorption value is 158-162 m2Between/g, in a PE separator for a batteryThe material has high dispersibility, and also has considerable hydrophilicity and good practicability.
(2) The preparation method of the silicon dioxide with high oil absorption value and high specific surface area is simple to operate, stable in process, capable of recycling byproducts, capable of effectively saving resources and capable of protecting the environment.
Detailed Description
The present invention is further illustrated by the following description of specific embodiments, which are not intended to limit the invention, and various modifications and improvements can be made by those skilled in the art based on the basic idea of the invention, but the invention is within the protection scope of the invention.
Wherein, the reagents used in the invention are all common reagents and can be purchased from common reagent production and sale companies.
Example 1 preparation of silica for storage battery with high oil absorption value and high specific surface area by precipitation method
The precipitation method for preparing the high-oil-absorption-value high-specific-surface-area silicon dioxide for the storage battery comprises the following preparation steps of:
s1, mixing the mixture for 30m3Adding a sodium sulfate solution with the mass percent concentration of 0.2 wt.% into a reaction tank, and then adding 1m3Heating the sodium silicate aqueous solution with the concentration of 2.0mol/L to 60 ℃, and keeping the pressure in the tank body at 0.3 MPa;
s2 stirring at 10Hz to form a solution of 4m3Dropwise adding 3mol/L sulfuric acid solution at a dropwise adding speed per hour, adjusting the pH value in the reaction tank to 9, stopping adding acid, keeping the pressure and the temperature in the tank unchanged, and aging the obtained seed crystals for 30 minutes;
s3, adding 1m of the aged seed crystal obtained in the step S23After being diluted by water, the temperature in the reaction tank is raised to 80 ℃, the pressure is unchanged, then sodium silicate aqueous solution and sulfuric acid solution are simultaneously dripped, the concentration of the sulfuric acid solution is 7mol/L, and the dripping speed is 5m3H; the concentration of the sodium silicate aqueous solution is 2.0mol/L, and the dropping speed is 25m3H; the tank pH was maintained at 9 until 22m of addition3After the sodium silicate aqueous solution is added, stoppingAdding alkali;
s4, continuing to maintain the pressure, the temperature and the stirring frequency in the system in the step S3, adding a sulfuric acid solution with the concentration of 3.5mol/L, stopping adding acid when the pH value at the end of the reaction is controlled to be 3, and continuing to stir for 20 minutes;
s5, performing filter pressing and washing on the silicon dioxide obtained in the step S4, removing water in the materials by adopting an enhanced airflow drying technology, and crushing the materials to obtain the silicon dioxide with the particle size of 10 microns.
Example 2 preparation of silica for storage battery with high oil absorption value and high specific surface area by precipitation method
The precipitation method for preparing the high-oil-absorption-value high-specific-surface-area silicon dioxide for the storage battery comprises the following preparation steps of:
s1, mixing 33m3Sodium sulfate solution with a mass percent concentration of 0.4 wt.% was added to the reaction tank, followed by 1.5m3Heating a sodium silicate aqueous solution with the concentration of 2.3mol/L to 70 ℃, and keeping the pressure in the tank body at 0.4 MPa;
s2, stirring at 30Hz to 5m3Dropwise adding a sulfuric acid solution with the concentration of 3.5mol/L at the dropwise adding speed/h, adjusting the pH value in the reaction tank to be 10, stopping adding acid, keeping the pressure and the temperature in the tank unchanged, and aging the obtained seed crystal for 60 minutes;
s3, adding the aged seed crystal obtained in the step S2 to 2m3After being diluted by water, the temperature in the reaction tank is raised to 85 ℃, the pressure is unchanged, then sodium silicate aqueous solution and sulfuric acid solution are simultaneously dripped, the concentration of the sulfuric acid solution is 7.5mol/L, and the dripping speed is 5.5m3H; the concentration of the sodium silicate aqueous solution is 2.3mol/L, and the dropping speed is 28m3H; the tank pH was maintained at 10 until 25m of addition3Stopping adding alkali after the sodium silicate aqueous solution is added;
s4, continuing to maintain the pressure, the temperature and the stirring frequency in the system in the step S3, adding a sulfuric acid solution with the concentration of 3.8mol/L, stopping adding acid when the pH value at the end of the reaction is controlled to be 4, and continuing to stir for 30 minutes;
s5, performing filter pressing and washing on the silicon dioxide obtained in the step S4, removing water in the materials by adopting an enhanced airflow drying technology, and crushing the materials until the particle size is 15 mu m.
Example 3 preparation of silica for storage battery having high oil absorption value and high specific surface area by precipitation method
The precipitation method for preparing the high-oil-absorption-value high-specific-surface-area silicon dioxide for the storage battery comprises the following preparation steps of:
s1, mixing 35m3Adding a sodium sulfate solution with the mass percent concentration of 0.6 wt.% into a reaction tank, and then adding 2m3Heating the sodium silicate aqueous solution with the concentration of 2.5mol/L to 80 ℃, and keeping the pressure in the tank body at 0.5 MPa;
s2 stirring at 50Hz to obtain a solution of 6m3Dropwise adding a sulfuric acid solution with the concentration of 4mol/L at the dropwise adding speed per hour, adjusting the pH value in the reaction tank to be 11, stopping adding acid, keeping the pressure and the temperature in the tank unchanged, and aging the obtained seed crystals for 90 minutes;
s3, adding 3m of aged seed crystal obtained in the step S23After being diluted by water, the temperature in the reaction tank is raised to 90 ℃, the pressure is unchanged, then sodium silicate aqueous solution and sulfuric acid solution are simultaneously dripped, the concentration of the sulfuric acid solution is 8mol/L, and the dripping speed is 6m3H; the concentration of the sodium silicate aqueous solution is 2.5mol/L, and the dropping speed is 30m3H; the tank pH was kept at 11 until 27m was added3Stopping adding alkali after the sodium silicate aqueous solution is added;
s4, continuing to maintain the pressure, the temperature and the stirring frequency in the system in the step S3, adding a sulfuric acid solution with the concentration of 4mol/L, stopping adding acid when the pH value at the end of the reaction is controlled to be 5, and continuing to stir for 40 minutes;
s5, performing filter pressing and washing on the silicon dioxide obtained in the step S4, removing water in the materials by adopting an enhanced airflow drying technology, and crushing the materials to obtain the silicon dioxide with the particle size of 20 microns.
Comparative example 1 preparation of silica for storage battery having high oil absorption value and high specific surface area by precipitation method
Comparative example 1 is different from example 2 in that the sodium sulfate solution in step S1 has a concentration of 3 wt.% and an addition of 10m3Other parameters and actionsThe same procedure was followed as in example 2.
Comparative example 2 preparation of silica for storage battery having high oil absorption value and high specific surface area by precipitation method
Comparative example 2 is different from example 2 in that no pressure is applied to the whole reaction process, and other parameters and operations are the same as example 2.
Comparative example 3 preparation of silica for storage battery having high oil absorption value and high specific surface area by precipitation method
Comparative example 3 is different from example 2 in that the stirring frequency during the reaction is 100Hz, and other parameters and operations are the same as example 2.
Comparative example 4 preparation of silica for storage battery having high oil absorption value and high specific surface area by precipitation method
Comparative example 4 is different from example 2 in that the sulfuric acid concentration in the step S3 is 4mol/L, and other parameters and operations are the same as those of example 2.
Comparative example 5 preparation of silica for storage battery having high oil absorption value and high specific surface area by precipitation method
Comparative example 5 is different from example 2 in that the aged seed crystal obtained in step S2 was not diluted with water in step S3, and other parameters and operation were the same as example 2.
Comparative example 6 preparation method of white carbon black for PE partition plate
See the preparation method in Chinese patent CN 101597065A.
Test example I, Performance test of silica for battery prepared by the invention and having high oil absorption value and high specific surface area
1. Test materials: examples 1 to 3, comparative examples 1 to 6.
2. The detection method comprises the following steps:
(1) and (3) oil absorption value detection: detection was performed according to the measurement of 5.13 oil absorption value in QB/T2346-2007.
(2) Specific surface area and pore size detection: the specific surface area and the pore diameter of the silicon dioxide are detected by using a static nitrogen adsorption method.
3. Test results
The test results are shown in table 1.
TABLE 1
Group of
Yield (%)
Oil absorption number (ml/100g)
Specific surface area (m)2/g)
Example 1
99.1
285
158
Example 2
99.3
296
162
Example 3
98.5
291
160
Comparative example 1
82.1
243
220
Comparative example 2
80.6
241
140
Comparative example 3
89.7
274
148
Comparative example 4
92.8
217
108
Comparative example 5
93.4
184
97
Comparative example 6
98.2
230
123
As shown in Table 1, the silicon dioxide prepared by the embodiments 1 to 3 of the invention has the yield of over 98 percent, the oil absorption value of 285 to 296ml/100g, the specific surface area of 158 to 162m2(iii) between/g, wherein the best effect of example 2 is the best embodiment of the present invention. In comparative examples 1 to 5, when some reaction conditions in the preparation process of the present invention were changed, the yield, oil absorption value, specific surface area, and other properties of the obtained silica were all decreased. Therefore, the steps of the preparation method of the silicon dioxide supplement each other, the prepared silicon dioxide is beneficial to improving the oil absorption value and the specific surface area, and the preparation method is suitable for being applied to the PE separator for the storage battery.
Test example II Performance of silica prepared according to the present invention applied to PE separator
1. Test materials: examples 1 to 3, comparative examples 1 to 5.
2. The detection method comprises the following steps: the silicon dioxide prepared in the embodiments 1 to 3 and the comparative examples 1 to 5 is applied to a PE partition board, and the prepared PE partition board is detected according to the method of 6.6 resistance, 6.7 porosity determination and 6.9 pickling weight loss in the mechanical industry standard JB/T7630.5-2008.
3. Test results
The test results are shown in table 2.
TABLE 2
Group of
Resistance (m omega cm)2)
Porosity (%)
Acid loss (%)
Example 1
25.6
84
1.7
Example 2
23.9
88
1.4
Example 3
26.8
80
2.1
Comparative example 1
41.6
66
5.6
Comparative example 2
39.5
62
3.6
Comparative example 3
45.3
73
3.9
Comparative example 4
46.7
75
7.1
Comparative example 5
35.2
57
7.6
As can be seen from table 2, after the silica prepared in embodiments 1 to 3 of the present invention is applied to the PE separator, the porosity of the PE separator is high, which can reach more than 80%, the acid loss is small, the resistance is small, the long-term stability of the prepared PE separator can be improved, and the service life of the battery can be effectively prolonged. In examples 1 to 3, the silica obtained in example 2 is the most effective in application, and is the most preferable example of the present invention. Compared with the embodiment 2, the comparative examples 1 to 5 change some reaction conditions, and the results are changed to different degrees when applied to the indexes of the PE partition board, so that the prepared silicon dioxide is applied to the PE partition board without the preparation method provided by the invention, the porosity is reduced, the acid weight loss and the resistance are increased, and the silicon dioxide is not suitable for the PE partition board.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.