Colloidal electrolyte for colloidal battery and preparation method thereof

Abstract

The present invention belongs to the technical field of colloidal batteries, and specifically relates to a colloidal electrolyte for colloidal batteries and a preparation method thereof. The invention comprises the following raw materials in percentage by mass: 2-5% fumed silica; 30-40% sulfuric acid; 0.1-0.6% ethylene glycol; 0.5-1.2% disodium hydrogen phosphate; and 0.1-1% thickener; the remainder being water for the battery. The thickener is guar gum or pectin. By introducing ethylene glycol to assist in dispersing the fumed silica and adjusting the pH value of the colloidal stock solution by adding disodium hydrogen phosphate, storage stability is significantly improved, the ionic environment of the electrolyte is optimized, and battery performance is enhanced. At the same time, through the synergistic effect of silica and the thickener, the amount of silica used in the colloidal electrolyte is reduced, the internal resistance of the battery is effectively reduced, and the capacity at different discharge rates is increased, providing reliable technical support for the application of valve-regulated colloidal batteries.

Description

Technical Field

[0001] The invention belongs to the technical field of colloidal batteries, and in particular relates to a colloidal electrolyte for colloidal batteries and a preparation method thereof. Background Art

[0002] The colloidal electrolyte for valve-regulated colloidal batteries is typically prepared by mixing a gelling agent (such as silica sol or silica) with a sulfuric acid solution. However, existing electrolytes using silica as a gelling agent have significant drawbacks: Firstly, silica's short gelling time makes it difficult to store the electrolyte for extended periods, increasing the complexity of the production process. Secondly, the silica content directly affects electrolyte performance. When the silica content is too low, hydration stratification is likely to occur, while excessive silica content leads to reduced electrolyte fluidity and increased battery internal resistance, which in turn affects the battery's charge and discharge efficiency and capacity. Furthermore, the traditional preparation process requires the addition of multiple auxiliary additives to stabilize the electrolyte system, further increasing the complexity of the formulation and production costs. Therefore, there is an urgent need to develop a colloidal electrolyte and its preparation method that exhibits stable gelling properties, is simple to process, and maintains optimal battery performance. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a colloidal electrolyte for colloidal batteries. By introducing ethylene glycol to assist in dispersing fumed silica and adjusting the pH value of the colloidal stock solution by adding disodium hydrogen phosphate, the storage stability is significantly improved, the ionic environment of the electrolyte is optimized, and the battery performance is enhanced. At the same time, through the synergistic effect of silica and thickener, the amount of silica in the colloidal electrolyte is reduced, the internal resistance of the battery is effectively reduced, and the capacity at different discharge rates is increased, providing reliable technical support for the application of valve-regulated colloidal batteries.

[0004] Another object of the present invention is to provide a method for preparing a colloidal electrolyte for a colloidal battery, which adopts a staged preparation process to achieve immediate mixing and use of the electrolyte, overcoming the timeliness limitation of traditional processes.

[0005] The technical solutions adopted by the present invention are as follows:

[0006] The colloidal electrolyte for the colloidal battery comprises the following raw materials in percentage by mass:

[0007] Fumed silica: 2~5%;

[0008] Sulfuric acid: 30~40%;

[0009] Ethylene glycol: 0.1~0.6%;

[0010] Disodium hydrogen phosphate: 0.5~1.2%;

[0011] Thickener: 0.1~1%;

[0012] The balance is water for the battery;

[0013] The thickener is guar gum or pectin;

[0014] Preferably, the mass percentage of the pectin is 0.5-1.0%; the mass percentage of the guar gum is 0.10-0.50%.

[0015] The guar gum is hydroxypropyl guar gum.

[0016] The pectin is high methoxy pectin, and its methoxy content is 8.2-11.4 wt.%.

[0017] The battery water is deionized water with a resistivity of ≥1×10 5 Ω·cm.

[0018] The fumed silica is hydrophilic fumed silica with a specific surface area of ​​175~225m 2 / g.

[0019] The sulfuric acid is CP grade sulfuric acid with a concentration of 95 wt.% or more.

[0020] The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps:

[0021] (1) Add ethylene glycol to a portion of the battery water and stir thoroughly, then add fumed silica and stir and disperse using a dispersing device. After the dispersion is uniform, add disodium hydrogen phosphate and continue mixing until uniform to obtain a colloidal stock solution;

[0022] (2) Sulfuric acid is added to the remaining battery water to prepare a sulfuric acid solution, and the sulfuric acid solution is mixed evenly with the colloidal stock solution in step (1), and then a thickener is added and stirred evenly to obtain a colloidal electrolyte for a colloidal battery.

[0023] In the step (1), the mass ratio of fumed silica to battery water is (10-20): (90-80).

[0024] In the step (1), the rotation speed of the dispersion equipment is 2000-2500 r / min, and the dispersion time is 15-20 min.

[0025] In the step (1), the viscosity of the colloid stock solution is less than 10 Pa·s and the pH value is 8-10.

[0026] In step (2), the temperature of the sulfuric acid solution and the colloid stock solution must be cooled to below 15°C before mixing.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention significantly extends the storage stability of the colloidal stock solution by introducing ethylene glycol to assist in dispersing fumed silica and combining it with disodium hydrogen phosphate to adjust the pH value of the colloidal stock solution, while simplifying the production process. When the colloidal stock solution is mixed with sulfuric acid solution, the phosphoric acid and sodium sulfate generated by the reaction of disodium hydrogen phosphate and sulfuric acid further optimize the ionic environment of the electrolyte and improve the electrical performance of the battery;

[0029] (2) The present invention uses the synergistic effect of fumed silica and a thickener (pectin or guar gum) to reduce the amount of silica used while effectively suppressing the hydration stratification phenomenon of the electrolyte, thereby reducing the internal resistance of the battery and increasing the capacity at different discharge rates;

[0030] (3) The present invention adopts a staged preparation process (i.e., first preparing a colloidal stock solution that can be stored for a long time, and then mixing it with a sulfuric acid solution as needed), realizing a "mix and use" production model, which can ensure the perfusion fluidity of the electrolyte and avoid the timeliness limitation caused by the short gelation time in the traditional process; and compared with the direct dispersion method (i.e., directly dispersing silica in a sulfuric acid solution), it eliminates the acid resistance restriction of the dispersion equipment and reduces the production input cost;

[0031] (4) The present invention reduces the complexity of raw materials by reducing the types of auxiliary additives, and improves production efficiency and product consistency by optimizing process parameters. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the following examples, but they do not limit the implementation of the present invention.

[0033] Unless otherwise specified, the raw materials used in the examples and comparative examples are conventional commercially available raw materials, and the process methods used in the examples and comparative examples are conventional methods in the art unless otherwise specified.

[0034] Some of the raw materials used in the examples and comparative examples are described as follows:

[0035] The guar gum is hydroxypropyl guar gum;

[0036] The methoxy content of the pectin is (10±1) wt.%;

[0037] The fumed silica is hydrophilic fumed silica with a specific surface area of ​​(200±25) m 2 / g;

[0038] The sulfuric acid is CP grade sulfuric acid with a concentration of (95.5±0.5) wt.%;

[0039] The battery water is deionized water, and its resistivity is (5×10 5 )Ω·cm.

[0040] Example 1

[0041] The colloidal electrolyte for the colloidal battery comprises the following raw materials in percentage by mass:

[0042] Fumed silica: 2%;

[0043] Sulfuric acid: 38.7%;

[0044] Ethylene glycol: 0.1%;

[0045] Disodium hydrogen phosphate: 0.5%;

[0046] Pectin: 1%;

[0047] The balance is water for the battery;

[0048] The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps:

[0049] (1) Add 0.5 kg of ethylene glycol to 87 kg of battery water and stir thoroughly. Then add 10 kg of fumed silica and stir and disperse it using a disperser. The speed of the disperser is 2000 r / min and the dispersion time is 15 min. After the dispersion is uniform, add 2.5 kg of disodium hydrogen phosphate and continue mixing until it is uniform to obtain a colloidal stock solution. The viscosity of the colloidal stock solution is measured to be 0.8 Pa·s and the pH value is 8.7. The obtained colloidal stock solution is cooled to 10°C for use.

[0050] (2) 38.7 kg of sulfuric acid was added to 40.3 kg of battery water to prepare 79 kg of sulfuric acid solution. After cooling to 10°C, the solution was mixed evenly with 20 kg of the cooled colloidal stock solution in step (1). Then, 1 kg of pectin was added and stirred evenly to obtain a colloidal electrolyte for colloidal batteries.

[0051] The colloidal electrolyte of the colloidal battery was poured into a GFMJ-200 battery, and after charging (charging at a constant current of 20 A until the voltage rose to 2.7 V and remained stable for 3 hours) and activated, the battery was left to stand for 12 hours to allow the electrolyte to fully gel.

[0052] Example 2

[0053] The colloidal electrolyte for the colloidal battery comprises the following raw materials in percentage by mass:

[0054] Fumed silica: 5%;

[0055] Sulfuric acid: 31%;

[0056] Ethylene glycol: 0.5%;

[0057] Disodium hydrogen phosphate: 1%;

[0058] Guar gum: 0.1%;

[0059] The balance is water for the battery;

[0060] The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps:

[0061] (1) Add 2.0 kg of ethylene glycol to 74 kg of battery water and stir thoroughly. Then add 20 kg of fumed silica and stir and disperse it in a disperser at a speed of 2500 r / min for 20 min. After the dispersion is uniform, add 4 kg of disodium hydrogen phosphate and continue mixing until uniform to obtain a colloidal stock solution. The viscosity of the colloidal stock solution is measured to be 7 Pa·s and the pH value is 9.3. The obtained colloidal stock solution is cooled to 10°C for use.

[0062] (2) 31 kg of sulfuric acid was added to 43.9 kg of battery water to prepare 74.9 kg of sulfuric acid solution. After cooling to 10°C, the solution was mixed evenly with 25 kg of the cooled colloidal stock solution in step (1). Then, 0.1 kg of guar gum was added and stirred evenly to obtain a colloidal electrolyte for colloidal batteries.

[0063] The colloidal electrolyte of the above-mentioned colloidal battery was poured into 4 OPzV 200 cells, charged (charged at a constant current of 20 A until the voltage rose to 2.7 V and remained stable for 3 hours), activated, and then allowed to stand for 12 hours to allow the electrolyte to fully gel.

[0064] Example 3

[0065] The colloidal electrolyte for the colloidal battery comprises the following raw materials in percentage by mass:

[0066] Fumed silica: 4.5%;

[0067] Sulfuric acid: 35.6%;

[0068] Ethylene glycol: 0.6%;

[0069] Disodium hydrogen phosphate: 1.2%;

[0070] Pectin: 0.5%;

[0071] The balance is water for the battery;

[0072] The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps:

[0073] (1) Add 2.0 kg of ethylene glycol to 79 kg of battery water and stir thoroughly. Then add 15 kg of fumed silica and stir and disperse it in a disperser at a speed of 2200 r / min for 20 min. After the dispersion is uniform, add 4 kg of disodium hydrogen phosphate and continue mixing until uniform to obtain a colloidal stock solution. The viscosity of the colloidal stock solution is measured to be 4.2 Pa·s and the pH value is 8.6. The obtained colloidal stock solution is cooled to 10°C for use.

[0074] (2) 35.6 kg of sulfuric acid was added to 33.9 kg of battery water to prepare 69.5 kg of sulfuric acid solution. After cooling to 10°C, the solution was mixed evenly with 30 kg of the cooled colloidal stock solution in step (1). Then, 0.5 kg of pectin was added and stirred evenly to obtain a colloidal electrolyte for colloidal batteries.

[0075] The colloidal electrolyte of the colloidal battery was poured into a 6 OPzV 600 battery, and after charging (charging at a constant current of 60 A until the voltage rose to 2.7 V and remained stable for 3 hours) and activated, the battery was left to stand for 12 hours to allow the electrolyte to fully gel.

[0076] Comparative Example 1

[0077] The colloidal electrolyte for the colloidal battery comprises the following raw materials in percentage by mass:

[0078] Fumed silica: 2%;

[0079] Sulfuric acid: 38.7%;

[0080] Ethylene glycol: 0.1%;

[0081] Disodium hydrogen phosphate: 0.5%;

[0082] The balance is water for the battery;

[0083] The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps:

[0084] (1) Same as Example 1;

[0085] (2) 38.7 kg of sulfuric acid was added to 41.3 kg of battery water to prepare 80 kg of sulfuric acid solution, which was cooled to 10°C and then mixed evenly with 20 kg of the cooled colloidal stock solution in step (1) to obtain a colloidal electrolyte for a colloidal battery.

[0086] The colloidal electrolyte for the colloidal battery was poured into a GFMJ-200 battery and activated by charging (charging at a constant current of 20 A until the voltage rose to 2.7 V and remained stable for 3 hours). The battery was then left to stand for 12 hours. The electrolyte showed gel-acid separation, indicating that the pectin added in Example 1 could play a role in thickening and stabilizing.

[0087] Comparative Example 2

[0088] The colloidal electrolyte for the colloidal battery comprises the following raw materials in percentage by mass:

[0089] Fumed silica: 5%;

[0090] Sulfuric acid: 31%;

[0091] Ethylene glycol: 0.5%;

[0092] Disodium hydrogen phosphate: 1%;

[0093] The balance is water for the battery;

[0094] The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps:

[0095] (1) Same as Example 2;

[0096] (2) 31 kg of sulfuric acid was added to 44 kg of battery water to prepare 75 kg of sulfuric acid solution, which was cooled to 10°C and then mixed evenly with 25 kg of the cooled colloidal stock solution in step (1) to obtain a colloidal electrolyte for a colloidal battery.

[0097] The colloidal electrolyte for the colloidal battery was poured into a 4 OPzV 200 battery and activated by charging (charging at a constant current of 20 A until the voltage rose to 2.7 V and remained stable for 3 hours). The battery was then left to stand for 12 hours. The electrolyte showed gel-acid separation, indicating that the guar gum added in Example 2 could play a role in thickening and stabilizing the electrolyte.

[0098] In the absence of a thickener, for a colloidal electrolyte system with the same sulfuric acid content, in order to achieve an ideal gelation effect, the amount of silicon dioxide added to the colloidal electrolyte needs to be increased, as shown in Comparative Examples 3 and 4.

[0099] Comparative Example 3

[0100] The colloidal electrolyte for the colloidal battery comprises the following raw materials in percentage by mass:

[0101] Fumed silica: 3.5%;

[0102] Sulfuric acid: 38.7%;

[0103] Ethylene glycol: 0.175%;

[0104] Disodium hydrogen phosphate: 0.875%;

[0105] The balance is water for the battery;

[0106] The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps:

[0107] (1) Same as Example 1;

[0108] (2) 38.7 kg of sulfuric acid was added to 26.3 kg of battery water to prepare 65 kg of sulfuric acid solution, which was cooled to 10°C and then mixed evenly with 35 kg of the cooled colloidal stock solution in step (1) to obtain a colloidal electrolyte for a colloidal battery.

[0109] The colloidal electrolyte of the colloidal battery was poured into a GFMJ-200 battery, and after charging (charging at a constant current of 20 A until the voltage rose to 2.7 V and remained stable for 3 hours) and activated, the battery was left to stand for 12 hours to allow the electrolyte to fully gel.

[0110] Comparative Example 4

[0111] The colloidal electrolyte for the colloidal battery comprises the following raw materials in percentage by mass:

[0112] Fumed silica: 7%;

[0113] Sulfuric acid: 31%;

[0114] Ethylene glycol: 0.7%;

[0115] Disodium hydrogen phosphate: 1.4%;

[0116] The balance is water for the battery;

[0117] The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps:

[0118] (1) Same as Example 2;

[0119] (2) 31 kg of sulfuric acid was added to 34 kg of battery water to prepare 65 kg of sulfuric acid solution, which was cooled to 10°C and then mixed evenly with 35 kg of the cooled colloidal stock solution in step (1) to obtain a colloidal electrolyte for a colloidal battery.

[0120] The colloidal electrolyte of the colloidal battery was poured into 4 OPzV 200 cells, charged (charged at a constant current of 20 A until the voltage rose to 2.7 V and remained stable for 3 hours), activated, and then allowed to stand for 12 hours to allow the electrolyte to fully gel.

[0121] With reference to YDT 1360-2005, the performance of the batteries assembled in Examples 1-2 and Comparative Examples 3-4 were tested, and the test results are shown in Table 1.

[0122] Table 1 Performance test results

[0123]

[0124] In Table 1, Example 1 and Comparative Example 3 used the same dry cell model, and Example 2 and Comparative Example 4 also used the same dry cell model. Furthermore, the sulfuric acid content in the electrolytes used in Example 1 and Comparative Example 3 was the same, and the sulfuric acid content in the electrolytes used in Example 2 and Comparative Example 4 was also the same. While maintaining the same gelling effect, the amount of silica used in the colloidal electrolytes in Examples 1 and 2 was reduced by adding a thickener.

[0125] It can be seen from the test data in Table 1 that, compared with the corresponding comparative example, the battery in the embodiment has lower internal resistance and better battery discharge performance, especially high-rate discharge performance.

[0126] Comparative Example 5

[0127] The preparation method of the colloid stock solution comprises the following steps:

[0128] 0.5 kg of ethylene glycol was added to 89.5 kg of battery water and stirred thoroughly. Then, 10 kg of fumed silica was added and stirred and dispersed using a disperser at a speed of 2000 r / min for 15 minutes. The viscosity was measured to be 10 Pa·s and the pH value was 4.2.

[0129] Comparative Example 6

[0130] The preparation method of the colloid stock solution comprises the following steps:

[0131] 10 kg of fumed silica was added to 87.5 kg of battery water and stirred and dispersed using a disperser at a speed of 2000 r / min for 30 min. After uniform dispersion, 2.5 kg of disodium hydrogen phosphate was added and mixing continued until uniform, resulting in a colloidal stock solution with a measured viscosity of 0.7 Pa·s and a pH of 9.1.

[0132] Comparative Example 7

[0133] The preparation method of the colloid stock solution comprises the following steps:

[0134] 2.0 kg of ethylene glycol was added to 78 kg of battery water and stirred thoroughly. Then, 20 kg of fumed silica was added and stirred and dispersed using a disperser at a speed of 2500 r / min for 20 minutes. The viscosity was measured to be 40 Pa·s and the pH value was 3.3.

[0135] Comparative Example 8

[0136] The preparation method of the colloid stock solution comprises the following steps:

[0137] 20 kg of fumed silica was added to 76 kg of battery water and dispersed using a disperser at a speed of 2500 r / min for 40 minutes. After uniform dispersion, 4 kg of disodium hydrogen phosphate was added and mixing continued until uniform. The viscosity was measured to be 6.3 Pa·s and the pH value was 9.8.

[0138] Comparing Comparative Example 5 and Comparative Example 7 with Example 1 and Example 2, respectively, it can be seen that in Example 1 and Example 2, the viscosity of the colloid stock solution is significantly reduced due to the addition of disodium hydrogen phosphate to the colloid stock solution.

[0139] Comparing Comparative Examples 6 and 8 with Examples 1 and 2, respectively, it can be seen that in Examples 1 and 2, the addition of ethylene glycol to the colloidal stock solution shortens the dispersion time of the fumed silica in the battery water.

[0140] At room temperature, the colloid solutions prepared in Example 1, Example 2, Comparative Example 5 and Comparative Example 7 were allowed to stand for 2 h, 6 h, 12 h, 24 h, 48 h and 72 h, respectively, and the fluidity of the colloid solutions was observed. The results are shown in Table 2.

[0141] Table 2 Fluidity of colloid stock solution

[0142]

[0143] As can be seen from Table 2, compared with Comparative Examples 5 and 7, the gel time of the colloid stock solutions of Examples 1 and 2 was significantly prolonged due to the addition of disodium hydrogen phosphate, and the fluidity did not change significantly within 72 hours, and the processability was better.

Claims

1. A colloidal electrolyte for a colloidal battery, characterized in that: The following raw materials are included in the following percentages by mass: Fumed silica: 2~5%; Sulfuric acid: 30~40%; Ethylene glycol: 0.1~0.6%; Disodium hydrogen phosphate: 0.5~1.2%; Thickener: 0.1~1%; The balance is water for the battery; The thickener is guar gum or pectin; The battery water is deionized water; The method for preparing the colloidal electrolyte for the colloidal battery comprises the following steps: (1) Add ethylene glycol to a portion of the battery water and stir thoroughly, then add fumed silica and stir and disperse using a dispersing device. After the dispersion is uniform, add disodium hydrogen phosphate and continue mixing until uniform to obtain a colloidal stock solution; (2) adding sulfuric acid to the remaining battery water to prepare a sulfuric acid solution, mixing the sulfuric acid solution with the colloidal stock solution in step (1) uniformly, then adding a thickener, and stirring uniformly to obtain a colloidal electrolyte for a colloidal battery; In the step (1), the speed of the dispersion equipment is 2000-2500 r / min, and the dispersion time is 15-20 min; In the step (1), the viscosity of the colloid stock solution is less than 10 Pa·s and the pH value is 8-10.

2. The colloidal electrolyte for colloidal storage batteries according to claim 1, characterized in that: The specific surface area of ​​the fumed silica is 175~225m 2 / g.

3. The colloidal electrolyte for colloidal storage batteries according to claim 1, characterized in that: The guar gum is hydroxypropyl guar gum.

4. The colloidal electrolyte for colloidal storage batteries according to claim 1, characterized in that: The methoxy content of the pectin is 8.2-11.4 wt.%.

5. The colloidal electrolyte for colloidal storage batteries according to claim 1, characterized in that: The resistivity of the battery water is ≥1×10 5 Ω·cm.

6. The method for preparing a colloidal electrolyte for a colloidal battery according to claim 1, wherein: In the step (1), the mass ratio of fumed silica to battery water is (10-20): (90-80).

7. The method for preparing a colloidal electrolyte for a colloidal battery according to claim 1, wherein: In step (2), the temperature of the sulfuric acid solution and the colloid stock solution must be cooled to below 15°C before mixing.

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