JP7315810B2 - Method for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione - Google Patents

Description

The present invention belongs to the technical field of battery electrolyte additives, and relates to the use of 4,4′-bi-1,3-dioxolane-2,2′-dione as a battery electrolyte additive. ,4'-bi-1,3-dioxolane-2,2'-diones.

Although the performance of lithium-ion batteries is improving and its application range is expanding, its safety issues and cycle performance restrict the development of lithium-ion batteries to some extent. In particular, lithium-ion batteries for electric vehicles, which are currently popular, are focused on safety performance, quick charging performance, and battery life. This is the starting point. There are many factors that affect the safety and cycle stability of lithium-ion batteries, which are mainly divided into two factors: internal factors and external factors. The internal factors are mainly related to the stability of the positive and negative active materials, the properties of the electrolyte itself and compatibility with the electrode materials, the stability of the separator materials, etc. The external factors are mainly the improper use of the battery and the abuse that appears in the process of use. phenomenon. Research shows that the introduction of electrolyte additives is a very effective method, which can not only improve the properties of the electrolyte itself, but also improve the compatibility between the electrolyte and electrode materials, and , the addition of a small amount has a clear effect. By modifying the electrode material, the cycle stability of the lithium ion battery can be further improved.

In recent years, a number of new electrolyte additives for multifunctional lithium-ion batteries have emerged. As a result of research, 4,4'-bi-1,3-dioxolane-2,2'-dione, which has a CAS number of 24690-44-6, is used as an electrolyte additive in positive and negative electrodes of lithium ion batteries. It has been found that the structural stability and thermal stability of the material can be effectively improved. In addition, 4,4'-bi-1,3-dioxolane-2,2'-dione exhibits excellent cycle and safety performance under high voltage, extreme temperature and low temperature conditions, and greatly improves the performance of lithium ion batteries. Has a stimulating effect. However, the conventional synthesis process of 4,4'-bi-1,3-dioxolane-2,2'-dione is not mature, and the raw materials are usually expensive and the process is complicated during the synthesis process. There are problems such as low yield and purity of the product, and in the current synthesis process of 4,4'-bi-1,3-dioxolane-2,2'-dione, the reaction should generally be carried out at high temperature. It is believed that there are For example, when the reaction is performed at 60 to 130° C. for 12 hours or more, the yield can reach about 88 to 90%, but the reaction temperature is high, the reaction is unstable, and the reaction time is too long, resulting in production efficiency. affects For this reason, research on methods for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione is of great practical significance.

In order to solve the above technical problems, the present invention provides a method for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione. The synthetic method according to the present invention is simple, the raw materials are cheap and readily available, the energy consumption is low, the reaction conditions are mild and stable, and the yields are high.

The present invention uses the following technical means in order to achieve its object.

Add imidazole and tetrahydrofuran to the reactor under an argon gas atmosphere, cool down to −5 to 5° C., start dropping phosgene, finish dropping over 0.5 to 1 hour, and finish dropping for 0.5 to 1 hour. After stirring and filtering to obtain a filtrate containing 1,1′-carbonyldiimidazole, the filtrate is added dropwise to a tetrahydrofuran solution of erythritol at a temperature of −8 to −15° C. The dropwise addition was completed over time, stirred for 0.5-2 hours while maintaining temperature, the solvent was removed in vacuo to obtain a residue, the residue was dissolved in dichloromethane, washed with cold water, dried and concentrated4. ,4'-bi-1,3-dioxolane-2,2'-dione crude product is obtained, the crude product is purified, purified 4,4'-bi-1,3-dioxolane-2, Synthesis of 4,4'-bi-1,3-dioxolane-2,2'-dione with 2'-dione.

The molar ratio of phosgene, imidazole and erythritol is 1:(3-6):(0.45-0.8).

Erythritol is 1 g/4-4.5 ml in tetrahydrofuran solution. That is, 1 g of erythritol is contained in 4-4.5 ml of tetrahydrofuran solution.

Wash 2-3 times with cold water.

Dry with anhydrous sodium sulfate and/or calcium oxide.

Concentrate, control the degree of vacuum to 0.08-0.10 MPa, and concentrate at a temperature of 50-60° C. for 1.5-2 hours.

Recrystallize with acetone for purification.

When the solvent is removed by vacuum, the degree of vacuum is controlled to 0.08-0.09 Mpa, and the vacuum treatment time is 30-40 minutes.

As the effects of the present invention, the raw materials used in the present invention are inexpensive and easily available, the synthesis method is simple and easy to operate, the energy consumption is low, the reaction time is short, the reaction conditions are mild and stable, The product yield is high and can reach over 94%.

The present application uses a low-temperature reaction to break through the situation in which a high-temperature reaction is conventionally considered necessary, and develops a new method for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione. . Those skilled in the art know that when preparing 4,4'-bi-1,3-dioxolane-2,2'-dione, a long-term reaction at elevated temperature accelerates the progress of the reaction, yielding 4,4'-bi-1, It contributes to the synthesis of 3-dioxolane-2,2′-dione, and when the temperature is low, it affects the progress of the reaction, slows down the reaction rate, lowers the yield, and additionally produces 4,4′-bi-1,3 -Dioxolane-2,2'-dione cannot be synthesized. The inventors have studied for a long time and produced 4,4'-bi-1,3-dioxolane-2,2'-dione using phosgene, imidazole, and erythritol as raw materials, thereby achieving low-temperature, short-time reaction synthesis. and the yield can reach 94% or more.

FIG. 1 is a cycle performance diagram of an LP063450AR type prismatic lithium ion battery with a rated capacity of 950 mAh. FIG. 2 is a cycle performance diagram of an LP063450AR type prismatic lithium ion battery with a rated capacity of 950 mAh to which 4,4'-bi-1,3-dioxolane-2,2'-dione of the present invention is added. FIG. 3 is a mass spectrum of 4,4'-bi-1,3-dioxolane-2,2'-dione produced according to the present invention. FIG. 4 is a cutaway view of FIG. 3;

The present invention will be further described based on specific examples below.
1. Specific embodiment

Example 1
In an argon gas atmosphere, 4.0 mol of imidazole and 125 ml of tetrahydrofuran were placed in a four-necked flask, cooled to 0° C., and 1.0 mol of phosgene was started dropwise, and the dropwise addition was completed over 0.5 hours. , 0.5 hours, and filtered to obtain a filtrate containing 1,1′-carbonyldiimidazole. Then, at a temperature of −10° C., the filtrate was added dropwise to a tetrahydrofuran (250 ml) solution containing 0.5 mol of erythritol, and the dropwise addition was completed over 1.5 hours. was removed to give a residue. The residue was dissolved in dichloromethane and washed twice with cold water. 20 g of anhydrous sodium sulfate was added for drying and concentration to obtain a crude product of 4,4'-bi-1,3-dioxolane-2,2'-dione. The crude product was recrystallized to obtain 82.20 g of pure 4,4'-bi-1,3-dioxolane-2,2'-dione (yield 94.4%).
The resulting 4,4'-bi-1,3-dioxolane-2,2'-dione was collected and measured to have a density of 1.6075 g/cm3 and a boiling point of 535.33°C (760 mmHg). , the purity detected by HPLC was 99.87%.

Example 2
Put 3.0 mol of imidazole and 62 ml of tetrahydrofuran in a four-necked flask under an argon gas atmosphere, cool down to -2°C, start dropping 1.0 mol of phosgene, and finish dropping over 0.6 hours. The mixture was stirred for 0.6 hours and filtered to obtain a filtrate containing 1,1′-carbonyldiimidazole. Then, at a temperature of −8° C., the filtrate was added dropwise to a tetrahydrofuran (220 ml) solution containing 0.45 mol of erythritol, and the dropwise addition was completed over 1 hour. was removed to give a residue. The residue was dissolved in dichloromethane and washed twice with cold water. 20 g of anhydrous sodium sulfate was added for drying and concentration to obtain a crude product of 4,4'-bi-1,3-dioxolane-2,2'-dione. The crude product was recrystallized to obtain 74.4 g of pure 4,4'-bi-1,3-dioxolane-2,2'-dione (yield 94.96%).
The resulting 4,4'-bi-1,3-dioxolane-2,2'-dione was collected and measured to have a density of 1.6083 g/cm3 and a boiling point of 535.38°C (760 mmHg). , the purity detected by HPLC was 99.89%.

Example 3
Put 5.0 mol of imidazole and 204 ml of tetrahydrofuran in a four-necked flask under an argon gas atmosphere, cool down to -5°C, start dropping 1.0 mol of phosgene, and finish dropping over 0.8 hours. The mixture was stirred for 0.8 hour and filtered to obtain a filtrate containing 1,1′-carbonyldiimidazole. Then, at a temperature of −12° C., the filtrate was added dropwise to a tetrahydrofuran (384 ml) solution containing 0.7 mol of erythritol, and the dropwise addition was completed over 1.2 hours. Solvent was removed at rt to give a residue. The residue was dissolved in dichloromethane and washed twice with cold water. 20 g of anhydrous sodium sulfate was added for drying and concentration to obtain a crude product of 4,4'-bi-1,3-dioxolane-2,2'-dione. The crude product was recrystallized to obtain 82.95 g of pure 4,4'-bi-1,3-dioxolane-2,2'-dione (yield 95.29%).
The resulting 4,4'-bi-1,3-dioxolane-2,2'-dione was collected and measured to have a density of 1.6078 g/cm3 and a boiling point of 535.47°C (760 mmHg). , the purity detected by HPLC was 99.91%.

Example 4
Place 6.0 mol of imidazole and 164 ml of tetrahydrofuran in a four-necked flask under an argon gas atmosphere, cool down to 5° C., start dropping 1.0 mol of phosgene, and finish dropping over 1 hour. The mixture was stirred for hours and filtered to obtain a filtrate containing 1,1′-carbonyldiimidazole. Then, at a temperature of −15° C., the filtrate was added dropwise to a tetrahydrofuran (307 ml) solution containing 0.6 mol of erythritol, and the dropwise addition was completed over 1.5 hours. was removed to give a residue. The residue was dissolved in dichloromethane and washed twice with cold water. 20 g of anhydrous sodium sulfate was added for drying and concentration to obtain a crude product of 4,4'-bi-1,3-dioxolane-2,2'-dione. The crude product was recrystallized to obtain 83.4 g of pure 4,4'-bi-1,3-dioxolane-2,2'-dione (yield 95.8%).
The resulting 4,4'-bi-1,3-dioxolane-2,2'-dione was collected and measured to have a density of 1.609 g/cm3 and a boiling point of 535.71°C (760 mmHg). , the purity detected by HPLC was 99.85%.

Example 5
In an argon gas atmosphere, 4.0 mol of imidazole and 136 ml of tetrahydrofuran were placed in a four-neck flask, cooled to 3° C., and 1.0 mol of phosgene was started dropwise, and the dropwise addition was completed over 0.7 hours. , 0.7 hours, and filtered to obtain a filtrate containing 1,1′-carbonyldiimidazole. Then, at a temperature of −13° C., the filtrate was added dropwise to a tetrahydrofuran (420 ml) solution containing 0.8 mol of erythritol, and the dropwise addition was completed over 1.3 hours. Solvent was removed at rt to give a residue. The residue was dissolved in dichloromethane and washed twice with cold water. 20 g of anhydrous sodium sulfate was added for drying and concentration to obtain a crude product of 4,4'-bi-1,3-dioxolane-2,2'-dione. The crude product was recrystallized to obtain 83.74 g of pure 4,4'-bi-1,3-dioxolane-2,2'-dione (yield 96.2%).
The resulting 4,4'-bi-1,3-dioxolane-2,2'-dione was collected and measured to have a density of 1.6087 g/cm3 and a boiling point of 535.64°C (760 mmHg). , the purity detected by HPLC was 99.86%.

Example 6
Place 4.0 mol of imidazole and 125 ml of tetrahydrofuran in a four-necked flask under an argon gas atmosphere, cool down to -3°C, start dropping 1.0 mol of phosgene, and finish dropping over 0.9 hours. The mixture was stirred for 0.9 hours and filtered to obtain a filtrate containing 1,1′-carbonyldiimidazole. Then, at a temperature of −9° C., the filtrate was added dropwise to a tetrahydrofuran (268 ml) solution containing 0.5 mol of erythritol, and the dropwise addition was completed over 1.4 hours. Solvent was removed at rt to give a residue. The residue was dissolved in dichloromethane and washed twice with cold water. 20 g of anhydrous sodium sulfate was added for drying and concentration to obtain a crude product of 4,4'-bi-1,3-dioxolane-2,2'-dione. The crude product was recrystallized to obtain 84 g of pure 4,4'-bi-1,3-dioxolane-2,2'-dione (yield 96.5%).
The resulting 4,4'-bi-1,3-dioxolane-2,2'-dione was collected and measured to have a density of 1.6073 g/cm3 and a boiling point of 535.38°C (760 mmHg). , the purity detected by HPLC was 99.86%.

Example 7
Place 4.0 mol of imidazole and 125 ml of tetrahydrofuran in a four-necked flask under an argon gas atmosphere, cool down to -1°C, start dropping 1.0 mol of phosgene, and finish dropping over 0.6 hours. The mixture was stirred for 0.6 hours and filtered to obtain a filtrate containing 1,1′-carbonyldiimidazole. Then, at a temperature of −11° C., the filtrate was added dropwise to a tetrahydrofuran (240 ml) solution containing 0.45 mol of erythritol, and the dropwise addition was completed over 1.2 hours. Solvent was removed at rt to give a residue. The residue was dissolved in dichloromethane and washed twice with cold water. 20 g of anhydrous sodium sulfate was added for drying and concentration to obtain a crude product of 4,4'-bi-1,3-dioxolane-2,2'-dione. The crude product was recrystallized to obtain 76.23 g of pure 4,4'-bi-1,3-dioxolane-2,2'-dione (yield 97.3%).
The obtained 4,4'-bi-1,3-dioxolane-2,2'-dione was collected and subjected to mass spectrometric detection, and the mass spectrum was detected with reference to FIGS. 3 and 4. FIG. Density was determined to be 1.6088 g/cm 3 , boiling point was 535.68° C. (760 mmHg), and purity was 99.84% as detected by HPLC.

2. Test performance 1. Study of high-temperature performance The lithium-ion battery used in the experiment is a BYD LP063450AR type prismatic lithium-ion battery with a rated capacity of 950mAh. The battery was subjected to a charge-discharge cycle test at 25 ° C. and 5 ° C. at 1C magnification (950 mA), using a constant current constant voltage charging system (CC-CV) and a constant current discharging system, and the charging / discharging voltage range was 3.0 ~ 4.5V. First, charge at a constant current of 1C to 4.5V, then charge at a constant voltage of 4.5V until the current drops to 20mA or less, then discharge at a constant current of 1C until the final voltage reaches 3.0V. do. In this way, the battery is repeatedly charged and discharged 500 times, and the cycle data is collected by the LAND-2001T type battery measurement system.

Please refer to FIG. After 300 cycles, the battery that was repeatedly charged and discharged at 25°C had a capacity retention rate of 88.8%, and the capacity of the battery at 65°C was only 73.1%, showing a rapid decrease in capacity. It was found that the BYD LP063450AR type prismatic lithium ion battery with a rated capacity of 950 mAh had poorer cycle stability at 65°C than cycle stability at 25°C. From FIG. 1 it was further found that the battery has a higher discharge capacity at 65° C. than the rated capacity of the battery. This is because the viscosity of the electrolyte is reduced at high temperatures, the mobility of lithium ions is improved, the utilization of active lithium is increased, and the lithium battery exhibits high charge-discharge capacity.

In order to verify that the 4,4'-bi-1,3-dioxolane-2,2'-dione produced in the present invention has the function of improving the high-temperature performance of batteries, the rated capacity manufactured by BYD was A 950 mAh type LP063450AR prism type lithium ion battery was tested, and 4,4′-bi-1,3-dioxolane-2,2′-dione having an electrolytic solution weight of 2% was added to the electrolyte of the battery. was added, and the same operation was repeated to detect the high-temperature cycle performance of the battery.

Please refer to FIG. After 300 cycles, the battery to which 4,4′-bi-1,3-dioxolane-2,2′-dione of the present invention was added had a battery capacity of 87.6% at 65° C., and a capacity of 65% after 500 cycles. °C, the capacity of the battery is 75.2%. The battery to which the 4,4'-bi-1,3-dioxolane-2,2'-dione of the present invention was not added had a battery capacity of 59% at 65°C after 500 cycles, indicating the end of life. It was found that 4,4'-bi-1,3-dioxolane-2,2'-dione prepared according to the present invention can improve the cycle performance of batteries at high voltage and high temperature.

2. Investigation of low-temperature performance LiFePO4 lithium ion battery is the object of investigation, the size is 12 cm × 7 cm × 0.8 cm, the single battery rated capacity is 10 Ah, and the operating voltage is 3.3 to 4.2 V. , the case is aluminum plastic film. A low temperature test was performed. 25°C is taken as a low temperature test reference point, and from 25°C to -20°C, every 5°C is a temperature inspection point, and the temperature change rate is 30min/5°C. Performance tests can be performed in Table 1 shows the test results.

Table 1 Effect of temperature on discharge capacity (0.5C)

As can be seen from Table 1 above, the lower the temperature, the greater the attenuation of the capacity. This experimental study indicates that there is a problem of poor low-temperature cycle performance.

In order to verify that the 4,4'-bi-1,3-dioxolane-2,2'-dione produced in the present invention has the function of improving the low temperature performance of the battery, the same LiFePO4 lithium ion battery as above was tested. As a subject of investigation, 4,4′-bi-1,3-dioxolane-2,2′-dione having a mass of 2% of the electrolyte solution was added to the electrolyte solution of the battery, and the same operation as described above was repeated to obtain the battery. The low temperature cycle performance was detected. Table 2 shows the results.

Table 2 Effect of temperature on discharge capacity (0.5C)

As can be seen from Table 2, the low temperature cycling performance of the battery can be improved after adding the 4,4'-bi-1,3-dioxolane-2,2'-dione of the present invention.

Claims (6)

Add imidazole and tetrahydrofuran to the reactor under an argon gas atmosphere, cool down to −5 to 5° C., start dropping phosgene, finish dropping over 0.5 to 1 hour, and finish dropping for 0.5 to 1 hour. After stirring and filtering to obtain a filtrate containing 1,1′-carbonyldiimidazole, the filtrate is added dropwise to a tetrahydrofuran solution of erythritol at a temperature of −8 to −15° C. The dropwise addition was completed over time, stirred for 0.5-2 hours while maintaining temperature, the solvent was removed in vacuo to obtain a residue, the residue was dissolved in dichloromethane, washed with cold water, dried and concentrated4. ,4'-bi-1,3-dioxolane-2,2'-dione crude product is obtained, the crude product is purified, purified 4,4'-bi-1,3-dioxolane-2, A method for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione, characterized in that 2'-dione is obtained. 4,4'-bi- according to claim 1, characterized in that the molar ratio of phosgene, imidazole and erythritol is 1:(3-6):(0.45-0.8) A method for synthesizing 1,3-dioxolane-2,2'-dione. The method for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione according to claim 1, characterized in that erythritol is 1g/4~4.5ml in the tetrahydrofuran solution. The method for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione according to claim 1, characterized by washing with cold water two to three times. 2. The method for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione according to claim 1, wherein drying is performed with anhydrous sodium sulfate and/or calcium oxide. The method for synthesizing 4,4'-bi-1,3-dioxolane-2,2'-dione according to claim 1, wherein the purification is recrystallization with acetone.