CN103824989B - A kind of PEG/PVC composite diaphragm and its preparation method and application - Google Patents

Abstract

The invention relates to a PEG/PVC composite separator and a preparation method and application thereof. The raw materials of the separator include PEG 1%-30%, PVC 15%-50%, silicon filler 20%-70%, and coupling agent 0.01%-1%. The preparation method is: mainly use PVC to build a three-dimensional microporous network structure to ensure the basic mechanical strength and corrosion resistance of the separator; blending and adding PEG to adjust the pore size of the three-dimensional network and improve the electrolyte on the surface of the hydrophobic PVC material Affinity; supplemented with a coupling agent modified silicon filler, the mechanical properties, electrolyte affinity, and pore tortuosity of the separator are further enhanced. On the basis of adhering to the strong mechanical properties and small average pore diameter of the microporous PVC separator, the prepared separator better improves the affinity with the colloidal electrolyte.

Description

A kind of PEG/PVC composite separator and its preparation method and application

technical field

The invention belongs to the field of chemical power sources, and in particular relates to a PEG/PVC composite separator and a preparation method and application thereof.

Background technique

Valve-regulated lead-acid batteries rely on two different methods to fix the electrolyte, one is AGM technology using glass fiber separators, and the other is colloid fixing technology using microporous PVC separators. The separators of the two technologies have their own advantages and disadvantages: the AGM separator has high porosity, low resistance, good electrolyte affinity, and low price, but the pore size is too large, the mechanical strength is low, and it is easy to cause acid stratification; The porous PVC separator has high mechanical strength and small pore size, but compared with the AGM separator, the porosity is relatively low, the resistance is relatively large, the affinity of the electrolyte is not good enough, and the price is expensive. Batteries using colloidal technology are more and more widely used because of their advantages such as long life and stable operation that AGM batteries do not have. However, due to cost considerations, AGM batteries are still widely used. There are even low-cost colloidal batteries combined with AGM separators and colloidal electrolytes in China. Because the separators are too thick, the colloidal electrolytes are difficult to pour in. After the glue is filled, there is a lot of air inside the battery, and the final battery performance does not meet expectations. Good effect.

As the "third plate" that plays an important role in the battery, the separator takes on more tasks in the colloidal valve-regulated lead-acid battery. In addition to the basic characteristics of high porosity, good mechanical strength, small pore size, small volume, and strong acid resistance, high-quality gel battery separators are also required to have good affinity for colloidal electrolytes. The affinity of the colloidal electrolyte includes two aspects: on the one hand, it should have good wettability during the glue filling process, which can quickly fill the glue and discharge the air in the separator; on the other hand, it should be in the process of forming a gel Among them, the separator can participate in the construction of a three-dimensional gel structure, so that the separator and the electrolyte gel can be firmly combined to avoid cracks at the interface between the separator and the electrolyte gel as the water decomposes.

At present, colloidal lead-acid batteries at home and abroad generally use microporous PVC separators, which can meet the requirements of the separator for pore size, mechanical strength, porosity, and strong acid resistance. The precipitated silica contained in the separator can also endow itself with hydrophobic properties. PVC separator has certain wettability and colloid affinity. However, the addition of silicon dioxide is limited, and the microporous PVC separator is only partially compatible with the electrolyte. Compared with the AGM separator, the separator itself still has too much resistance, and the preparation process of this separator is complicated and expensive. Need to rely on imports.

Contents of the invention

Based on the current situation of the domestic colloidal battery industry, and aiming at the special requirements of the colloidal battery separator, the present invention develops a PEG/PVC composite separator whose production cost is much lower than that of imported microporous PVC separators. This kind of PEG/PVC composite separator has good colloidal electrolyte affinity under the premise of ensuring the basic performance of the separator.

A PEG/PVC composite partition, the raw materials of which are calculated by mass fraction: PEG 1%-30%, PVC 15%-50%, silicon filler 20%-70%, and the sum of the mass fractions of the above raw materials is 100%.

The PEG is PEG with a degree of polymerization above 6000.

The PVC is one or more of PVC paste resins with a polymerization degree of 1200-1800, PVC resins with a polymerization degree of more than 1800, and PVC resins with a crosslinking degree of 1%-10%.

The silicon filler is one or more of fumed silica with a specific surface area of 200-500m ² /g, diatomite with a mesh size above 200, and precipitated silica with a mesh size above 200.

A method for preparing the above-mentioned PEG/PVC composite separator, mixing PVC, PEG, silicon filler, and coupling agent, adding a solution to make a casting liquid, heating and stirring at 20°C-100°C for 2-5h , into a sealed container; then put it in a water bath at 20°C-70°C for 2-4h, scrape the casting liquid into pieces with a scraper, and stand in the air for pre-phase separation for 10-600s; then solidify The primary separator is obtained by immersing the precipitation in the bath solution, and finally the primary separator is hot-pressed into a corrugated shape and dried to obtain the separator.

The coupling agent is one or both of organosiloxane and titanate coupling agent, and its dosage is 0.1-1% of the silicon filler mass.

The dissolving solution is one of dimethylformamide, dimethylacetamide, tetrahydrofuran and cyclohexanone.

The coagulation bath solution is an aqueous solution with a mass content of 0%-50% of the solution.

The application of the PEG/PVC composite separator as mentioned above is used for lead-acid gel batteries.

Significant advantage of the present invention is:

(1) The hydrophilic polymer PEG is added by blending, so that the surface of the PVC network in the separator has good hydrophilicity;

(2) The hydroxyl groups on the surface of PEG contained in the separator and the hydroxyl groups on the surface of the silicon filler can bond with the colloid in the electrolyte in large quantities to form a gel together, so that the separator and the electrolyte gel can be firmly combined for a long time ;

(3) By controlling the phase separation process of the PVC/PEG/solvent/non-solvent four-component system, a pore structure with high porosity, small pore size and reasonable circuitousness can be obtained.

Description of drawings

Fig. 1 is the SEM image of the separator surface prepared in Example 1;

Fig. 2 is the SEM image of the separator surface prepared in Example 2;

FIG. 3 is a scanning electron microscope image of the separator surface prepared in Example 3.

detailed description

The technical solutions of the present invention will be further described below through specific examples. The raw materials used in the present invention can be purchased in the market, or can be synthesized by methods known in the art.

Example 1

PVC23wt%, PEG9wt%, diatomaceous earth 68wt%.

1. Weigh 5g of PVC and 2g of PEG6000 and dissolve in 45g of DMF solution, add 0.39g of mother liquor of coupling agent (KH-550) with a mass content of 1%, and heat and stir at 100°C for 2 hours;

2. Weigh 15g of diatomaceous earth and add, continue heating and stirring for 1h;

3. Pour the mixture into a sealed container and place it in a water bath at 40°C for 3 hours for defoaming;

4. Scrape with a 500μm scraper to make a sheet, and let it stand for 600s;

5. Immerse in water at 70°C to release the mold into pieces, take it out after 3 hours, and dry at 60°C;

The surface morphology of the obtained separator is shown in FIG. 1 , which has a relatively high porosity and a relatively uniform pore size distribution, and the pore size is mostly between 1 μm and 10 μm. The porosity is 80.0%, the tensile strength is 5Mp, the initial contact angle of water droplets on the separator is 56°, and the wetting time by water is 2.5s.

Example 2

PVC30wt%, PEG18wt%, diatomaceous earth 52wt%.

1. Weigh 10g of PVC and 6g of PEG10000 and dissolve in 90g of DMF solution, add 0.13g of 1% coupling agent (KH-550) mother liquor, heat and stir at 70°C for 3h;

2. Weigh 17g of diatomaceous earth and add, continue to heat and stir for 1h;

3. Pour the mixture into a sealed container and place it in a water bath at 20°C for defoaming for 4 hours;

4. Scrape with a 750μm scraper to make a sheet, and let it stand for 300s;

5. Immerse in 25°C DMF aqueous solution with a mass content of 20%, demold it into pieces, take it out after 3 hours and dry it at 60°C;

The surface morphology of the obtained separator is shown in FIG. 2 , which has a relatively high porosity and a relatively uniform pore size distribution, which is between 1 μm and 10 μm. The porosity is 79.5%, the tensile strength is 5Mp, the initial contact angle of water droplets on the separator is 35°, and the wetting time by water is 1.5s.

Example 3

PVC49wt%, PEG18wt%, diatomaceous earth 33wt%.

1. Weigh 30g of PVC and 11g of PEG20000 and dissolve in 120g of DMF solution, add 0.13g of 1% coupling agent (KH-550) mother solution, heat and stir at 50°C for 5h;

2. Weigh 20g of diatomaceous earth and add, continue heating and stirring for 1h;

3. Pour the mixture into a sealed container and place it in a water bath at 70°C for 3 hours for defoaming;

4. Scrape with a 750μm scraper to make a sheet, and let it stand for 10s;

5. Immerse in a 90°C aqueous solution to release the mold into pieces, take it out after 3 hours and dry it at 60°C;

The surface morphology of the obtained separator is shown in Figure 3. The porosity is 77.0%, the tensile strength is 6Mp, the initial contact angle of water droplets on the separator is 58°, and the wetting time by water is 2s.

The final separator obtained in the three examples has a porosity of more than 75%, a maximum pore diameter of less than 10 μm, a tensile strength of more than 5Mp, a thickness of 0.5mm-1mm, and a water-wetting time of less than 3s. It is used in colloidal batteries Finally, the performance of the battery reaches the level of batteries assembled with imported separators.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (6)

1. the preparation method of a PEG/PVC composite diaphragm, it is characterised in that: by PVC, PEG, silicon filler, lysate, coupling agent It is mixed and made into cast panel liquid, injects and seal in container, be subsequently placed in vacuum defoamation 2-4h in 20 DEG C of-70 DEG C of water-baths；Will by scraper Cast panel liquid scraper plate is in blocks, stands pre-split-phase 10-600s in atmosphere；Then in coagulating bath aqueous solution, immersion precipitation obtains primary Dividing plate, is finally hot pressed into primary dividing plate bellows-shaped and dries prepared dividing plate；

PVC, PEG, the consumption of silicon filler be in parts by weight: PVC23wt%, PEG9wt%, kieselguhr 68wt%, PVC30wt%, One in PEG18wt%, kieselguhr 52wt%, or PVC49wt%, PEG18wt%, kieselguhr 33wt%.

The preparation method of PEG/PVC composite diaphragm the most according to claim 1, it is characterised in that: described PEG is polymerization Degree PEG more than 6000.

The preparation method of PEG/PVC composite diaphragm the most according to claim 1, it is characterised in that: described PVC is polymerization Spend in the polyvinyl chloride resin that polyvinyl chloride resin more than 1800 of the PVC paste resin of 1200-1800, the degree of polymerization, the degree of cross linking are 1%-10% One or more.

The preparation method of PEG/PVC composite diaphragm the most according to claim 1, it is characterised in that: described lysate is One in dimethylformamide, dimethyl acetylamide, oxolane, Ketohexamethylene.

The preparation method of PEG/PVC composite diaphragm the most according to claim 1, it is characterised in that: described coupling agent is Mass content is the KH-550 mother solution of 1%；When PVC consumption is 23wt%, the addition of coupling agent is 0.39g；When PVC consumption is During 30wt%, the addition of coupling agent is 0.13g；When PVC consumption is 49wt%, the addition of coupling agent is 0.13g.

The preparation method of PEG/PVC composite diaphragm the most according to claim 1, it is characterised in that: described solidification bath water Solution be lysate mass content be the aqueous solution of 0%-50%.