Electrolyte and preparation method and application thereof

Abstract

The invention discloses an electrolyte and a preparation method and application thereof. The electrolyte contains 0.5-5 parts of silicon dioxide, 5-98.5 parts of sulfuric acid and 1-15 parts of fluorine-containing carboxylic acid; the cycle stability of the colloidal lead-carbon battery is improved by dissolving a certain mass of organic compound containing fluorine and carboxyl in the electrolyte of the colloidal lead-carbon battery, the fluorine element has high electronegativity, the carboxyl is an excellent complexing agent of the lead element, the combination of the fluorine element and the carboxyl can strongly improve the crystallization process of lead sulfate, and the stability of the battery is improved. And the high electronegativity of the fluorine element can improve the adsorption energy of hydrogen ions in the colloid electrolyte on the surface of the carbon material, so that the purpose of inhibiting hydrogen evolution of the carbon material is achieved.

Description

Technical Field

[0001] The present application relates to an electrolyte and a preparation method and application thereof, belonging to the field of colloidal batteries. Background Art

[0002] Lead-carbon battery is an upgraded product of lead-acid battery. Adding an appropriate amount of carbon material to the negative electrode of lead-acid battery can greatly improve its cycle life in partially charged state. The role of carbon material is to enhance the conductivity of the negative electrode active material and delay the sulfation process. The sulfation process of the battery refers to the irreversible accumulation of lead sulfate, a discharge product. In addition to adding carbon material to increase the conductivity of the negative electrode, the key to improving this process is to prepare the electrolyte of the lead-carbon battery in the form of colloid and add specific additives to it to change the lead sulfate crystallization process to improve the cycle life of the battery. Summary of the invention

[0003] The present invention improves the cycle stability of the colloidal lead-carbon battery by dissolving a certain mass of fluorine-containing carboxylic acid in the electrolyte of the colloidal lead-carbon battery. The fluorine element has a strong electronegativity, and the carboxyl group is also an excellent complexing agent for the lead element. The combination of the two can strongly improve the crystallization process of lead sulfate, and the high electronegativity of the fluorine element can improve the adsorption energy of hydrogen ions in the colloidal electrolyte on the surface of the carbon material, thereby achieving the purpose of inhibiting hydrogen evolution of the carbon material.

[0004] According to one aspect of the present application, an electrolyte is provided, wherein the electrolyte contains silicon dioxide, sulfuric acid electrolyte, and fluorine-containing carboxylic acid;

[0005] Wherein, the content of each substance in the electrolyte is:

[0006] 0.5-5 parts of silicon dioxide;

[0007] 5 to 98.5 parts of sulfuric acid in sulfuric acid electrolyte;

[0008] 1 to 15 parts of fluorinated carboxylic acid.

[0009] The fluorine-containing carboxylic acid is selected from at least one of trifluoroacetic acid, difluoroacetic acid and pentafluoropropionic acid.

[0010] According to another aspect of the present application, there is provided an electrolyte as described above, comprising the following steps:

[0011] Silicon dioxide, sulfuric acid electrolyte, and fluorine-containing carboxylic acid are mixed to obtain the electrolyte.

[0012] The mass fraction of the sulfuric acid electrolyte is 1.05-1.5 g / ml.

[0013] According to another aspect of the present application, a colloidal battery electrolyte is provided, comprising the above-mentioned electrolyte.

[0014] According to another aspect of the present application, a colloidal battery is provided, comprising the colloidal battery electrolyte described above.

[0015] The beneficial effects of this application include:

[0016] The present invention improves the cycle stability of the colloidal lead-carbon battery by dissolving a certain mass of fluorine-containing and carboxyl organic compounds in the electrolyte of the colloidal lead-carbon battery. The fluorine element has a strong electronegativity, and the carboxyl group is also an excellent complexing agent for the lead element. The combination of the two can strongly improve the crystallization process of lead sulfate, and the high electronegativity of the fluorine element can improve the adsorption energy of hydrogen ions in the colloidal electrolyte on the surface of the carbon material, thereby achieving the purpose of inhibiting hydrogen evolution of the carbon material. DETAILED DESCRIPTION

[0017] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0018] Example 1

[0019] Step 1: Prepare the colloidal battery electrolyte by the following method:

[0020] A colloidal electrolyte was prepared by fully mixing 1 g of silicon dioxide, 90 g of a sulfuric acid electrolyte having a mass fraction of 1.275 g / ml (the mass concentration of the sulfuric acid electrolyte was 37%, i.e., the mass of pure sulfuric acid contained in the sulfuric acid solution was 33.3 g), and 9 g of trifluoroacetic acid.

[0021] Step 2: Prepare a colloidal lead-carbon battery by the following steps:

[0022] 1) Preparation of negative electrode: (1) Premix 600g lead powder, 9g activated carbon, 8.4g barium sulfate, and 0.3g polypropylene short fibers with a length of 5mm and a diameter of 0.5-1.5μm in a high-speed mixer, add 84g deionized water to the premixed powder while stirring, and continue stirring for 10 minutes to obtain lead paste; (2) Scrape the lead paste onto a metal lead grid with a size of 70mm long, 50mm wide, and 2mm thick, and cure and dry to obtain a lead-carbon battery negative electrode. The curing temperature is 40°C, the humidity is 80%, and the curing time is 20 hours; the drying temperature is 80°C, and the time is 24 hours;

[0023] 2) Preparation of the positive electrode: The positive electrode of the lead-acid battery is prepared according to the same process steps as the negative electrode preparation steps (1) and (2), except that no carbon material is added to the positive electrode;

[0024] 3) Preparation of lead-carbon battery: three positive plates and two negative plates are placed in parallel with each other in an alternating manner, and a colloidal PE separator for lead-carbon battery is placed between the positive plates and the negative plates, and two negative plates are welded in parallel and three positive plates are welded in parallel respectively. The total mass of positive active material of the lead-acid battery (the total mass of the lead paste on the three positive plates after drying) is 60.0g, and the total mass of positive active material refers to the total mass of the lead paste contained in the three positive plates welded in parallel. The total mass of negative active material (the total mass of the lead paste on the two negative plates after drying) is 52.9g, and the total mass of negative active material refers to the total mass of the lead paste contained in the two negative plates welded in parallel. The positive and negative electrode grids use conventional lead grids with dimensions of 70mm long, 50mm wide and 2mm thick; the positive and negative electrodes are placed in a tightly assembled battery box, where the battery box is 76mm long, 40mm wide and 100mm high, and 83g of the above-prepared colloidal electrolyte is injected into the battery box; after testing, the conductivity of the colloidal electrolyte between the positive and negative electrodes of the battery under this condition is 706mS / cm.

[0025] The battery was subjected to a normal temperature life test: 4.2A constant current discharge for 59 seconds, 18A discharge for 1 second, 6.3A current 2.3V voltage constant current constant voltage charge for 60 seconds, the charge and discharge conditions were cycled 3600 times, then left to stand for 40 hours, and then the cycle life test was continued after 40 hours. The termination condition of the life test was that the battery voltage dropped below 1.2V;

[0026] The initial voltage of the assembled internal hybrid battery at room temperature and full charge is 2.2317V, and the internal hybrid battery can run 77345 cycles in the room temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead content under the same test conditions (7201 cycles), the room temperature cycle life of the internal hybrid lead-carbon battery can reach 10.7 times that of traditional lead-acid batteries.

[0027] The battery was tested for gas evolution at room temperature, and the test method was as follows: the battery was fully sealed with laboratory-specific commercial paraffin, and then an air duct was inserted into the exhaust port of the battery. The end of the air duct located inside the battery passed through a rubber plug with a length of 5 mm. The end of the air duct located outside the working electrode chamber was introduced into a device for testing gas volume by water displacement method. The inner and outer surfaces of the rubber plug through which the air duct passed and various connections between the air duct and the commercial water displacement method gas volume test device were firmly sealed with commercial AB glue, in order to ensure that the gas generated by the battery end was completely introduced into the commercial water displacement method gas volume measuring device, and the gas volume generated by the battery end was collected by the device, and the gas production rate was calculated. During the test, the battery system was placed in a constant temperature environment of 25°C, and a constant voltage of 2.4V was applied to both ends of the battery for 48 hours. It was calculated that the gas production rate of the lead-carbon battery of the carbon material formula was 0.16ml / (wh·h).

[0028] Example 2

[0029] According to the requirements of Example 1, without changing other conditions, the amount of trifluoroacetic acid added in step 1 was changed to 1g, the conductivity of the assembled internal hybrid battery colloidal electrolyte was 717mS / cm, the starting voltage was 2.2639V at full charge at room temperature, and the assembled internal hybrid battery could run 67911 cycles in the normal temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead content under the same test conditions (7201 cycles), the normal temperature cycle life of the internal hybrid lead-carbon battery can reach 9.4 times the life of traditional lead-acid batteries. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.22ml / (wh·h).

[0030] Example 3

[0031] According to the requirements of Example 1, without changing other conditions, the amount of trifluoroacetic acid added in step 1 is changed to 15g, the conductivity of the assembled internal hybrid battery colloidal electrolyte is 691mS / cm, the starting voltage is 2.2358V at full charge at room temperature, and the assembled internal hybrid battery can run 52472 cycles in the normal temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead content under the same test conditions (7201 cycles), the normal temperature cycle life of the internal hybrid lead-carbon battery can reach 7.3 times the life of traditional lead-acid batteries. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.19ml / (wh·h).

[0032] Example 4

[0033] According to the requirements of Example 1, without changing other conditions, the amount of silicon dioxide added in step 1 is changed to 0.5g, the conductivity of the assembled internal hybrid battery colloidal electrolyte is 700mS / cm, the starting voltage is 2.2612V under full charge at room temperature, and the assembled internal hybrid battery can run 61197 cycles in the normal temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead content under the same test conditions (7201 cycles), the normal temperature cycle life of the internal hybrid lead-carbon battery can reach 8.5 times the life of traditional lead-acid batteries. The gas production rate of the assembled lead-carbon battery in room temperature environment is 0.20ml / (wh·h).

[0034] Example 5

[0035] According to the requirements of Example 1, without changing other conditions, the amount of silicon dioxide added in step 1 is changed to 5g, the conductivity of the assembled internal hybrid battery colloidal electrolyte is 712mS / cm, the starting voltage is 2.2394V under full charge at room temperature, and the assembled internal hybrid battery can run 58978 cycles in the normal temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead content under the same test conditions (7201 cycles), the normal temperature cycle life of the internal hybrid lead-carbon battery can reach 8.2 times the life of traditional lead-acid batteries. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.19ml / (wh·h).

[0036] Example 6

[0037] According to the requirements of Example 1, without changing other conditions, the trifluoroacetic acid added in step 1 is replaced with difluoroacetic acid of equal mass, the conductivity of the assembled internal hybrid battery colloidal electrolyte is 696mS / cm, the starting voltage is 2.2525V under full charge at room temperature, and the assembled internal hybrid battery can run 46759 cycles in the normal temperature life test. Compared with the test results of ordinary lead-acid batteries with the same lead content under the same test conditions (7201 cycles), the normal temperature cycle life of the internal hybrid lead-carbon battery can reach 6.5 times the life of traditional lead-acid batteries. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.15ml / (wh·h).

[0038] Comparative Example 1

[0039] Lead-acid battery: According to the requirements of Example 1, without changing other conditions, step 2 "1) Preparation of negative electrode: (1) Premix 600g lead powder, 9g activated carbon, 8.4g barium sulfate, and 0.3g polypropylene staple fibers with a length of 5mm and a diameter of 0.5-1.5μm in a high-speed mixer, add 84g deionized water to the premixed powder while stirring, and continue stirring for 10min to obtain lead paste;" is changed to (without adding any carbon material) "1) Preparation of negative electrode: (1) Premix 600g lead powder, 9g activated carbon, 8.4g barium sulfate, and 0.3g polypropylene staple fibers with a length of 5mm and a diameter of 0.5-1.5μm in a high-speed mixer, add 84g deionized water to the premixed powder while stirring, and continue stirring for 10min to obtain lead paste;" and other steps remain unchanged to prepare a colloidal lead-acid battery. The conductivity of the assembled internal hybrid battery colloidal electrolyte is 665mS / cm. The starting voltage of the assembled internal hybrid battery when fully charged at room temperature is 2.0965V, and it can run 7201 cycles in the room temperature life test.

[0040] Comparative Example 2

[0041] Lead-carbon battery: According to the requirements of Example 1, other conditions are not changed. No fluorinated carboxylic acid is added in the process of preparing the colloidal electrolyte in step 1. The conductivity of the assembled internal hybrid battery colloidal electrolyte is 672mS / cm. The initial voltage of the assembled internal hybrid battery at full charge at room temperature is 2.0542V, and it can run 8379 cycles in the normal temperature life test. Due to the lack of addition of fluorinated carboxylic acid, the battery cycle stability is poor and the hydrogen evolution of the battery cannot be suppressed. The gas production rate of the assembled lead-carbon battery at room temperature is 0.67ml / (wh·h).

[0042] Comparative Example 3

[0043] According to the requirements of Example 1, without changing other conditions, the trifluoroacetic acid added in step 1 is replaced with acetic acid of equal mass, and the conductivity of the assembled internal hybrid battery colloidal electrolyte is 677mS / cm, the starting voltage is 2.0878V under the fully charged state at room temperature, and the assembled internal hybrid battery can run 9382 cycles in the normal temperature life test. Since acetic acid lacks strong electronegative groups such as fluorine elements, its complexing ability with lead ions is too strong, which has a great influence on the crystallization process of lead sulfate, resulting in poor battery cycle performance and almost no ability to inhibit hydrogen evolution. The gas production rate of the assembled lead-carbon battery in a room temperature environment is 0.69ml / (wh·h).

[0044] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An electrolyte, characterized in that: The electrolyte contains silicon dioxide, sulfuric acid electrolyte, and fluorine-containing carboxylic acid; Wherein, the content of each substance in the electrolyte is: 0.5-5 parts of silicon dioxide; 5 to 98.5 parts of sulfuric acid in sulfuric acid electrolyte; 1 to 15 parts of fluorinated carboxylic acid.

2. The electrolyte according to claim 1, characterized in that The fluorine-containing carboxylic acid is selected from at least one of trifluoroacetic acid, difluoroacetic acid and pentafluoropropionic acid.

3. A method for preparing an electrolyte according to any one of claims 1 or 2, characterized in that: The following steps are involved: Silicon dioxide, sulfuric acid electrolyte, and fluorine-containing carboxylic acid are mixed to obtain the electrolyte.

4. The preparation method according to claim 3, characterized in that: The mass fraction of the sulfuric acid electrolyte is 1.05-1.5 g / ml.

5. A colloidal battery electrolyte, characterized in that: Containing the electrolyte according to any one of claims 1 or 2.

6. A colloidal battery, characterized in that: Contains the colloidal battery electrolyte as claimed in claim 5.