Storage battery electrolyte with low-temperature performance and preparation method thereof

Abstract

The invention discloses a storage battery electrolyte with low temperature performance and a preparation method thereof, the electrolyte is composed of a dilute H2SO4 substrate electrolyte with the specific gravity of 1.25 g / ml and a composite additive, the molar ratio of benzaldehyde to polyfluoroalkyl sulfonic acid to tetrabutylammonium hydrogen sulfate to acetophenone in the composite additive is 1: 2: 1: 3, and the mass ratio of benzaldehyde to polyfluoroalkyl sulfonic acid to tetrabutylammonium hydrogen sulfate to acetophenone to the substrate electrolyte is 0.1 wt%-0.3 wt%; during preparation, all the components of the composite additive are mixed according to the proportion and then added into dilute H2SO4 to be fully stirred until the components are completely dissolved, and the temperature of a system needs to be kept stable in the stirring process. According to the electrolyte, the low-temperature performance of the lead-acid battery can be remarkably improved, the discharge capacity is greatly improved in the environments of-10 DEG C and-18 DEG C, the charge acceptance is obviously enhanced, meanwhile, the normal-temperature 2hr capacity and the service life are considered, and hydrogen evolution and battery water loss can be inhibited. The high-power lead-acid battery is simple in preparation process and controllable in cost, is suitable for assembling high-power lead-acid batteries in the fields of communication, traffic and emergency equipment in the environment of-20 DEG C to 25 DEG C, and effectively solves the problem of poor low-temperature performance of a traditional lead-acid battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to a low-temperature performance battery electrolyte and its preparation method. Background Technology

[0002] Lead-acid batteries have a history of over 160 years and are one of the most important rechargeable batteries on the market today. Over this century, lead-acid batteries have undergone continuous development and improvement, achieving tremendous commercial success and being widely used in numerous fields. The market demand for lead-acid batteries is substantial; in 2019, the global market size exceeded US$43 billion. Lead-acid batteries have diverse applications and wide geographical distribution, and are affected by seasonal changes, especially in autumn and winter when temperatures are lower in northern regions. In most northern areas, the average temperature is between 0 and -10°C, and even below -20°C. Lower ambient temperatures significantly impact the performance of lead-acid batteries, especially those used outdoors. Adding additives to lead-acid batteries is an effective method to improve their low-temperature performance. Finding suitable lead-acid battery additives to improve battery performance in low-temperature environments has significant application value.

[0003] The impact of decreasing temperature on lead-acid battery performance is mainly reflected in two aspects: reduced discharge capacity and poor charge acceptance. As temperature decreases, the viscosity of the lead-acid battery electrolyte increases, the diffusion coefficient decreases, the conductivity decreases, and the internal resistance of the battery increases. This hinders ion transport within the battery, reducing the discharge capacity. Furthermore, the battery consumes sulfuric acid during discharge, leading to a decrease in sulfuric acid concentration and electrolyte freezing. Tiny ice crystals can clog the pores of the electrodes, hindering the reaction between the active materials and sulfuric acid, reducing the utilization rate of the active materials, which also contributes to a decrease in discharge capacity. The main reason for the poor charge acceptance of lead-acid batteries at low temperatures is that the solubility of lead sulfate in the electrolyte decreases rapidly at low temperatures. A large number of lead sulfate crystals precipitate from the electrolyte. These crystals can grow into larger, less soluble lead sulfate crystals, which are difficult to convert into lead and lead dioxide, making charging difficult and thus affecting the battery's lifespan. Poor low-temperature performance limits the application of lead-acid batteries in winter, especially in northern regions. Adding additives to lead-acid batteries is a common and effective way to improve their performance. Currently, there is little research on improving the low-temperature performance of lead-acid batteries and additives. Exploring the low-temperature performance of lead-acid batteries and finding additives that can effectively improve their low-temperature performance has important application value.

[0004] Electrolyte is a conductive liquid located between the positive and negative electrodes. In a battery, the primary function of the electrolyte is to ensure charge transfer, thereby maintaining charge balance during redox reactions. In lead-acid batteries, in addition to the above function, the electrolyte is also considered one of the three active substances participating in the reactions.

[0005] Lead-acid battery additives can be mainly divided into positive electrode additives, negative electrode additives, and electrolyte additives. The main purpose of adding additives to the electrolyte is to increase the energy density of lead-acid batteries and improve the utilization rate of positive and negative electrode active materials. Electrolyte additives can also enhance the reversibility of the charge and discharge reaction of lead-acid batteries. Hydrogen evolution occurs at the end of the charging process of lead-acid batteries, which will affect the service life of the battery. In order to suppress hydrogen evolution and extend the service life of the battery, additives can also be added to the electrolyte. The main functions of electrolyte additives added to sulfuric acid solution can be summarized in four aspects: (1) improving the utilization rate of active materials; (2) improving the reversibility of Pb cycling process; (3) improving the solubility of PbSO4 in the electrolyte; (4) suppressing hydrogen evolution.

[0006] Various organic compounds are added to lead-acid battery electrolytes to improve battery performance, such as benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate, and acetophenone. Acetophenone and benzaldehyde act as hydrogen evolution inhibitors in batteries, reducing water loss by up to 50%. Adding the surfactant polyfluoroalkyl sulfonic acid to VRLA batteries using AGM effectively inhibits hydrogen evolution and water loss, thus extending battery life by 1.5 to 2 times. Polyfluoroalkyl sulfonic acid uses fluoride ions to replace hydrogen ions, increasing its stability in the electrolyte. Adding tetrabutylammonium hydrogen sulfate to the electrolyte simultaneously increases the hydrogen evolution overpotential, increasing the peak currents of both the oxidation and reduction peaks at the positive electrode. The concentration of tetrabutylammonium hydrogen sulfate in the electrolyte affects the peak positions of the oxidation and reduction peaks.

[0007] Currently, two types of electrolytes are generally used in lead-acid batteries: ordinary sulfuric acid aqueous solution and colloidal electrolyte containing sulfuric acid. However, sulfate ions in lead-acid battery electrolytes participate in the charging and discharging reactions. During discharge, the electrolyte density decreases because sulfate ions are deposited on the electrodes. When the battery is charged, sulfate ions are released from both electrodes into the electrolyte, and the electrolyte density recovers. Therefore, the electrolyte has a significant impact on the performance of lead-acid batteries.

[0008] Therefore, it is necessary to develop a new electrolyte to effectively improve the performance degradation of lead-acid batteries under low-temperature conditions, thereby increasing battery life. Summary of the Invention

[0009] To address the problems in the prior art, the present invention proposes the following technical solution: A low-temperature performance battery electrolyte and its preparation method are disclosed, comprising a dilute H2SO4 base electrolyte and a composite additive, wherein the composite additive comprises benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate and acetophenone.

[0010] As a preferred embodiment of the above technical solution, the molar ratio of benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate, and acetophenone in the composite additive is 1:2:1:3.

[0011] As a preferred embodiment of the above technical solution, the specific gravity of the dilute H2SO4 substrate electrolyte is 1.25 g / ml.

[0012] As a preferred embodiment of the above technical solution, the mass ratio of the composite additive to the dilute H2SO4 base electrolyte is 0.1%wt to 0.3%wt.

[0013] A method for preparing a low-temperature performance battery electrolyte, based on the above-mentioned electrolyte, includes the following steps: mixing benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate and acetophenone in the stated molar ratio to obtain a composite additive; adding the composite additive to a dilute H2SO4 base electrolyte and stirring thoroughly until the additive is completely dissolved to obtain the low-temperature performance battery electrolyte.

[0014] As a preferred embodiment of the above technical solution, the electrolyte system temperature is kept stable during stirring to avoid local overheating that could alter the properties of the additives.

[0015] As a preferred embodiment of the above technical solution, the electrolyte is used to assemble a high-power lead-acid battery, which is suitable for communication, transportation, and emergency equipment applications in environments ranging from -20℃ to 25℃.

[0016] The beneficial effects of this invention are as follows: 1. Significantly improved low-temperature performance: In low-temperature environments such as -10℃ and -18℃, the battery discharge capacity is significantly increased compared to traditional electrolytes, while the charging acceptance capability is significantly enhanced, effectively solving the problems of capacity decay and charging difficulties caused by low temperatures.

[0017] 2. Balancing room temperature performance and lifespan: The synergistic effect of composite additives not only improves low-temperature performance but also increases the 2hr capacity at room temperature, while inhibiting hydrogen evolution and battery water loss, thus extending the overall battery lifespan.

[0018] 3. Simple preparation and controllable cost: The formula composition is clear, the preparation process only requires mixing, stirring and dissolving, the operation is convenient, the amount of additives is small, no additional complicated processes are required, and it is easy to promote industrialization. Attached Figure Description

[0019] Figure 1These are the 2hr capacity test curves of the lead-acid batteries prepared in Examples 1-3 and Comparative Example 1. Figure 2 These are the -18°C low-temperature discharge capacity test curves of the lead-acid batteries prepared in Examples 1-3 and Comparative Example 1. Figure 3 These are the -10℃ low-temperature discharge capacity test curves of the lead-acid batteries prepared in Examples 1-3 and Comparative Example 1. Figure 4 This is a test of the charge acceptance capability of the lead-acid batteries prepared in Examples 1-3 and Comparative Example 1. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0021] Example 1 A mixture of benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate, and acetophenone in a molar ratio of 1:2:1:3 was added as an electrolyte additive to dilute H2SO4 with a specific gravity of 1.25 g / ml and stirred thoroughly until the additive was completely dissolved. The prepared electrolyte was a dilute H2SO4 electrolyte with an additive content of 0.1% wt and a specific gravity of 1.25 g / ml.

[0022] Example 2 A mixture of benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate, and acetophenone in a molar ratio of 1:2:1:3 was added as an electrolyte additive to dilute H2SO4 with a specific gravity of 1.25 g / ml and stirred thoroughly until the additive was completely dissolved. The prepared electrolyte was a dilute H2SO4 electrolyte with an additive content of 0.2% wt and a specific gravity of 1.25 g / ml.

[0023] Example 3 A mixture of benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate, and acetophenone in a molar ratio of 1:2:1:3 was added as an electrolyte additive to dilute H2SO4 with a specific gravity of 1.25 g / ml and stirred thoroughly until the additive was completely dissolved. The prepared electrolyte was a dilute H2SO4 electrolyte with an additive content of 0.3% wt and a specific gravity of 1.25 g / ml.

[0024] Comparative Example 1 Dilute H2SO4 with a specific gravity of 1.25 g / ml.

[0025] 12V 100Ah lead-acid batteries were assembled using the electrolytes of Examples 1-3 and Comparative Example 1 according to current methods, and then the lead-acid batteries were subjected to 2hr capacity testing, low-temperature discharge capacity testing, and charge acceptance testing.

[0026] The 2-hour capacity test steps are as follows: S1. A fully charged battery is discharged at a current of I2 (50A) in an environment of 25℃±2℃ until the battery terminal voltage reaches 10.5V / cell. S2, the battery undergoes three charge-discharge cycles as per S1; S3. Record the charge-discharge curve of the third cycle to evaluate the battery's 2-hour capacity.

[0027] The low-temperature discharge capacity test procedure is as follows: S1. Place the fully charged battery in a low-temperature chamber and let it stand at -18℃ for 12 hours. Then, discharge it at I2 (50A) current at -18℃ until the battery terminal voltage reaches 10.5V / cell. Record the discharge time and capacity. S2. After the battery has finished discharging according to S1, place it in a -10℃ environment and charge it continuously for 20 hours at a constant voltage of 15.0V (current limited to 0.6I2 (30A)). S3. Then, discharge the battery at a current of I2 (50A) in a -10℃ environment until the battery terminal voltage reaches 10.5V / cell. Record the discharge time and capacity.

[0028] The charging acceptance test steps are as follows: S1. The fully charged battery undergoes three 2-hour capacity tests, and the maximum capacity Ca is taken, I0 = Ca / 10; S2, Discharge with current I0 for 5 hours; S3. After the discharge is complete, immediately place the battery in a low temperature chamber at 0±1℃ and let it stand for 24 hours. S4. Within 1 minute of taking the battery out of the low-temperature chamber, charge it at a constant voltage of 14.40±0.10V. After 10 minutes, record the charging current value Ica. S5. Evaluate the battery's charge acceptance capability using the ratio of charging current Ica to C2 / 10.

[0029] The 2-hour capacity test results of the lead-acid batteries prepared in Examples 1-3 and Comparative Example 1 at 25°C are attached. Figure 1 As shown, the 2hr capacity of the lead-acid batteries prepared in Examples 1 to 3 at 25°C is 97.44 to 105.23 Ah, which is significantly higher than the 2hr capacity of the lead-acid battery prepared in Comparative Example 1.

[0030] The -18°C low-temperature discharge capacity test results of the lead-acid batteries prepared in Examples 1-3 and Comparative Example 1 are attached. Figure 2 As shown, the -18°C low-temperature discharge capacity of the lead-acid batteries prepared in Examples 1 to 3 is 80.39 to 86.82 Ah, which is significantly higher than that of the lead-acid battery prepared in Comparative Example 1.

[0031] The -10°C low-temperature discharge capacity test results of the lead-acid batteries prepared in Examples 1-3 and Comparative Example 1 are attached. Figure 3 As shown, the -10℃ low-temperature discharge capacity of the lead-acid batteries prepared in Examples 1 to 3 is 91.93 to 99.28 Ah, which is significantly higher than that of the lead-acid battery prepared in Comparative Example 1.

[0032] The charge acceptance test results of the lead-acid batteries prepared in Examples 1-3 and Comparative Example 1 are attached. Figure 4 As shown, the lead-acid batteries prepared in Examples 1-3 exhibit significantly improved charge acceptance, ranging from 2.108 to 2.343 Ah, while the lead-acid battery prepared in Comparative Example 1 has a charge acceptance of only 2.009 Ah. The addition of a low-temperature performance lead-acid battery electrolyte can improve the battery's charge acceptance.

[0033] This invention effectively improves the low-temperature discharge performance of lead-acid batteries and reduces the impact of low temperature on battery capacity. At the same time, the preparation process is simple, easy to operate and low in cost.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall fall within the protection scope of the present invention.

Claims

1. A low-temperature performance battery electrolyte, characterized in that, It includes a dilute H2SO4-based electrolyte and a composite additive, wherein the composite additive includes benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate, and acetophenone.

2. The low-temperature performance battery electrolyte according to claim 1, characterized in that, The molar ratio of benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate, and acetophenone in the composite additive is 1:2:1:

3.

3. The low-temperature performance battery electrolyte according to claim 1, characterized in that, The specific gravity of the dilute H2SO4-based electrolyte is 1.25 g / ml.

4. The low-temperature performance battery electrolyte according to claim 1, characterized in that, The mass ratio of the composite additive to the dilute H2SO4 base electrolyte is 0.1%wt to 0.3%wt.

5. A method for preparing a low-temperature performance battery electrolyte, characterized in that, The electrolyte according to any one of claims 1-4 comprises the following steps: mixing benzaldehyde, polyfluoroalkyl sulfonic acid, tetrabutylammonium hydrogen sulfate and acetophenone in the molar ratio to obtain a composite additive; adding the composite additive to a dilute H2SO4 base electrolyte and stirring thoroughly until the additive is completely dissolved to obtain the low-temperature performance battery electrolyte.

6. The method for preparing the low-temperature performance battery electrolyte according to claim 5, characterized in that, During stirring, maintain a stable temperature in the electrolyte system to avoid localized overheating that could alter the properties of the additives.

7. The application of the low-temperature performance battery electrolyte according to any one of claims 1-4, characterized in that, The electrolyte is used to assemble high-power lead-acid batteries, which are suitable for communication, transportation, and emergency equipment applications in environments ranging from -20℃ to 25℃.

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