Polysaccharide electrolyte and preparation method and application thereof

Abstract

The invention discloses a polysaccharide electrolyte and a preparation method and application thereof. The polysaccharide electrolyte contains silicon dioxide, a sulfuric acid electrolyte and polysaccharide; the polysaccharide is selected from at least one of amylose, amylopectin and agar. The addition amount of silicon dioxide is reduced, the conductivity of the electrolyte is improved, and the electrochemical performance of the colloid lead-carbon battery is finally improved.

Description

Technical Field

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

[0002] Compared with traditional liquid-filled lead-carbon batteries, valve-regulated lead-carbon batteries (VRLA) with gel electrolyte have excellent performance in many fields. This type of battery is also called "colloidal lead-carbon battery". The key factor affecting the performance of colloidal lead-carbon batteries is the gel electrolyte itself.

[0003] There are many types of colloidal gelling agents. Most gelling agents use precipitated silica, which has good viscosity and cyclic stability during use, but it has many disadvantages, such as short coagulation time, high viscosity, high material and manufacturing costs, high internal resistance, etc. These disadvantages limit the widespread application of this type of battery. Gel electrolytes containing colloidal silica have the advantages of simple preparation, storage and gel infusion, and low cost. However, in order to enhance their thixotropic properties and improve their coagulation characteristics, a large amount of alkali metal elements or transition metal elements are usually added to them, which will lead to a decrease in the hydrogen evolution overpotential of the battery, an increase in the water consumption of the battery, and ultimately the battery drying up or even failure. Summary of the invention

[0004] In order to solve the problem that a large amount of alkali metal elements or transition metal elements need to be added during the preparation of the colloidal electrolyte, the amount of silicon dioxide added is reduced to solve the problems of low electrolyte conductivity and large internal resistance caused by them, the present invention improves the electrochemical performance of the colloidal lead-carbon battery by adding a certain amount of polysaccharide coagulant to the electrolyte of the colloidal lead-carbon battery. The addition of the polysaccharide coagulant can effectively improve the thixotropic properties of the colloidal electrolyte. The hydroxyl groups rich in the polysaccharide coagulant can form an effective cross-linked network with silicon dioxide and can also form an effective cross-linked network by itself, avoiding the addition of alkali metal elements or transition metal elements, greatly improving the thixotropic properties of the colloidal electrolyte, and increasing the amount of liquid acid added, thereby further reducing the internal resistance of the electrolyte, improving the conductivity of the electrolyte, and ultimately improving the electrochemical performance of the colloidal lead-carbon battery.

[0005] According to one aspect of the present application, a polysaccharide electrolyte is provided, characterized in that:

[0006] The polysaccharide electrolyte contains silicon dioxide, sulfuric acid electrolyte, and polysaccharide;

[0007] The polysaccharide is selected from at least one of amylose, amylopectin and agar.

[0008] In the polysaccharide electrolyte, the content of each substance is:

[0009] 0.5 to 500 parts of silicon dioxide;

[0010] 5 to 98.5 parts of sulfuric acid in sulfuric acid electrolyte;

[0011] 1 to 15 parts of polysaccharide.

[0012] In the polysaccharide electrolyte, the mass fractions of each substance are:

[0013] 0.5-80 parts of silicon dioxide;

[0014] 20-50 parts of sulfuric acid in sulfuric acid electrolyte;

[0015] Polysaccharide 9-15 parts.

[0016] The concentration of the sulfuric acid is 1.05-1.5 g / ml.

[0017] According to another aspect of the present application, a method for preparing the above-mentioned polysaccharide electrolyte is provided, comprising the following steps:

[0018] The polysaccharide electrolyte is obtained by mixing raw materials containing silicon dioxide, sulfuric acid electrolyte and polysaccharide.

[0019] According to another aspect of the present application, there is provided an application of the above-mentioned polysaccharide electrolyte for use in a colloidal battery.

[0020] The beneficial effects of this application include:

[0021] Reduce the amount of silicon dioxide added, increase the conductivity of the electrolyte, and ultimately improve the electrochemical performance of the colloidal lead-carbon battery. DETAILED DESCRIPTION

[0022] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0023] Example 1

[0024] Step 1: Prepare the colloidal battery electrolyte by the following method:

[0025] A colloidal electrolyte was prepared by fully mixing 80 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 agar.

[0026] Step 2: Prepare a colloidal lead-carbon battery by the following steps:

[0027] 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;

[0028] 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;

[0029] 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 726mS / cm.

[0030] 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;

[0031] The initial voltage of the assembled internal hybrid battery at room temperature is 2.201V when fully charged, and the internal hybrid battery can run 56491 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 7.9 times that of traditional lead-acid batteries.

[0032] Example 2

[0033] According to the requirements of Example 1, without changing other conditions, the amount of agar 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 2.203V under full charge at room temperature, and the assembled internal hybrid battery could run 53277 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 7.7 times the life of traditional lead-acid batteries.

[0034] Example 3

[0035] According to the requirements of Example 1, without changing other conditions, the amount of agar added in step 1 was changed to 15g, the conductivity of the assembled internal hybrid battery colloidal electrolyte was 712mS / cm, the starting voltage was 2.207V under full charge at room temperature, and the assembled internal hybrid battery could run 55612 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 5.9 times the life of traditional lead-acid batteries.

[0036] Example 4

[0037] According to the requirements of Example 1, without changing other conditions, the amount of silicon dioxide added in step 1 was changed to 0.5g, the conductivity of the assembled internal hybrid battery colloidal electrolyte was 720mS / cm, the starting voltage was 2.195V under full charge at room temperature, and the assembled internal hybrid battery could run 52431 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 5.7 times the life of traditional lead-acid batteries.

[0038] Example 5

[0039] According to the requirements of Example 1, without changing other conditions, the amount of silicon dioxide added in step 1 was changed to 500g, the conductivity of the assembled internal hybrid battery colloidal electrolyte was 710mS / cm, the starting voltage was 2.209V under full charge at room temperature, and the assembled internal hybrid battery could run 47453 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 5.0 times the life of traditional lead-acid batteries.

[0040] Example 6

[0041] According to the requirements of Example 1, without changing other conditions, the agar added in step 1 is replaced with an equal mass of amylopectin, the conductivity of the assembled internal hybrid battery colloidal electrolyte is 714mS / cm, the starting voltage is 2.198V under full charge at room temperature, and the assembled internal hybrid battery can run 47536 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 3.1 times the life of traditional lead-acid batteries.

[0042] Comparative Example 1

[0043] 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 677mS / cm. The starting voltage of the assembled internal hybrid battery when fully charged at room temperature is 2.131V, and it can run 7201 cycles in the room temperature life test.

[0044] Comparative Example 2

[0045] Lead-carbon battery: According to the requirements of Example 1, other conditions are not changed, and no polysaccharide coagulant is added in the process of preparing the colloidal electrolyte in step 1. The conductivity of the assembled internal hybrid battery colloidal electrolyte is 669mS / cm, and the initial voltage of the assembled internal hybrid battery is 2.116V in the fully charged state at room temperature, and it can run 10801 cycles in the room temperature life test. The poor performance of the battery colloidal electrolyte due to the lack of the addition of the polysaccharide coagulant ultimately leads to poor battery cycle stability.

[0046] Comparative Example 3

[0047] According to the requirements of Example 1, without changing other conditions, the agar added in step 1 is replaced with an equal mass of glucose (monosaccharide). The conductivity of the assembled internal hybrid battery colloidal electrolyte is 585mS / cm, the starting voltage is 2.133V at full charge at room temperature, and the assembled internal hybrid battery can run 10801 laps in the normal temperature life test. Since glucose (monosaccharide) is not a polysaccharide coagulant, it cannot form an effective cross-linking system with silica, and it cannot form a cross-linking network by itself, resulting in too low conductivity of the colloidal electrolyte. The conductivity of the assembled internal hybrid battery colloidal electrolyte is 627mS / cm, the starting voltage is 2.117V at full charge at room temperature, and the assembled internal hybrid battery can run 8364 laps in the normal temperature life test.

[0048] Comparative Example 4

[0049] According to the requirements of Example 1, without changing other conditions, step 1 "preparing a colloidal battery electrolyte by the following method: 1g of silicon dioxide, 90g of sulfuric acid electrolyte with a mass fraction of 1.275g / ml, and 9g of agar are fully mixed to prepare a colloidal electrolyte." is replaced by "preparing a colloidal battery electrolyte by the following method: 1g of silicon dioxide, 90g of sulfuric acid electrolyte with a mass fraction of 1.275g / ml, 8.5g of agar, and 0.5g of cobalt hydroxide are fully mixed to prepare a colloidal electrolyte." The conductivity of the assembled internal hybrid battery colloidal electrolyte is 651mS / cm, the starting voltage is 2.109V in the fully charged state at room temperature, and the assembled internal hybrid battery can run 8947 cycles in the normal temperature life test. Since the addition of cobalt hydroxide increases the amount of hydrogen evolution of the battery, the electrolyte is consumed too quickly, and the battery performance is poor.

[0050] 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. A polysaccharide electrolyte, characterized in that: The polysaccharide electrolyte contains silicon dioxide, sulfuric acid electrolyte, and polysaccharide; The polysaccharide is selected from at least one of amylose, amylopectin and agar.

2. The polysaccharide electrolyte according to claim 1, characterized in that In the polysaccharide electrolyte, the mass fractions of each substance are: 0.5 to 500 parts of silicon dioxide; 5 to 98.5 parts of sulfuric acid in sulfuric acid electrolyte; 1 to 15 parts of polysaccharide.

3. The polysaccharide electrolyte according to claim 1, characterized in that In the polysaccharide electrolyte, the mass fractions of each substance are: 0.5-80 parts of silicon dioxide; 20-50 parts of sulfuric acid in sulfuric acid electrolyte; Polysaccharide 9-15 parts.

4. The polysaccharide electrolyte according to claim 1, characterized in that The concentration of the sulfuric acid electrolyte is 1.05-1.5 g / ml.

5. A method for preparing the polysaccharide electrolyte according to any one of claims 1 to 4, characterized in that: The following steps are involved: The polysaccharide electrolyte is obtained by mixing raw materials containing silicon dioxide, sulfuric acid electrolyte and polysaccharide.

6. Use of the polysaccharide electrolyte according to any one of claims 1 to 4, characterized in that: For GEL batteries.