Synthesis method and application of high-temperature lithium battery electrolyte additive

Abstract

The invention discloses a synthesis method and application of a high-temperature lithium battery additive, and the specific preparation steps are as follows: metal halide is added into a solvent, heating reflux is performed, the metal halide is one or more of copper halide or aluminum halide, the solvent is one or more of thionyl chloride or sulfuryl chloride, the solvent is one or more of sodium hydroxide or sodium hydroxide, and heating reflux is performed to obtain the high-temperature lithium battery additive. And adding polyvinyl halide powder and anhydrous lithium tetrachloroaluminate, continuing heating reflux reaction until the color of the solution becomes yellow green, stopping heating, naturally cooling to room temperature, and filtering and drying to obtain the high-temperature lithium battery additive. When the additive prepared by the invention is used for the lithium / thionyl chloride battery electrolyte, the high and low temperature discharge performance of the battery can be effectively improved, and the long-acting storage performance and the working safety in a high temperature environment of the lithium / thionyl chloride battery can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium / thionyl chloride battery electrolytes, and particularly relates to a synthesis method and application of a high-temperature lithium battery electrolyte additive. Background Art

[0002] Thionyl chloride, also known as thionyl chloride, can be used in lithium-thionyl chloride batteries. Lithium-thionyl chloride batteries are electrochemical power sources using metallic lithium as the negative electrode and liquid thionyl chloride as the positive electrode active material and electrolyte. A solution formed by dissolving LiAlCl4 in SOCl2 is typically used as the inorganic electrolyte. For example, patent document No. 200410061326.1 discloses a method for preparing an electrolyte for a lithium-thionyl chloride battery. This method involves distilling and purifying SOCl2, then adding LiAlCl4, then adding metallic lithium, heating and refluxing to purify it, and then injecting SO2 gas for filtration to ultimately produce the lithium-thionyl chloride battery electrolyte.

[0003] A lithium / thionyl chloride (Li / SOCl2) battery uses lithium as the anode, carbon as the cathode carrier, and a thionyl chloride solution of anhydrous lithium tetrachloroaluminate as the electrolyte. Li / SOCl2 batteries boast high specific energy, high specific power, stable discharge voltage, and long storage life. They are widely used in military and civilian applications, including aerospace, underwater weapons, navigation equipment, geological exploration, and instrumentation. Currently, Li / SOCl2 batteries offer the highest specific energy and power in the battery industry. The overall reaction mechanism of a Li / SOCl2 battery is: 4Li + 2SOCl2 → 4LiCl + S + SO2. Sulfur and sulfur dioxide dissolve in an excess of thionyl chloride electrolyte. During discharge, sulfur dioxide generates a certain degree of pressure. During storage, once the lithium negative electrode comes into contact with the electrolyte, it reacts with the thionyl chloride electrolyte to form LiCl. This passivation film forms on the lithium negative electrode, protecting it from the electrolyte. This passivation film helps extend the battery's storage life.

[0004] For example, the patent document with application number 202211549479.5 discloses an electrolyte for a lithium thionyl chloride battery, which includes thionyl chloride and a pretreatment component, the pretreatment component includes lithium tetrachloroaluminate, an additive and an alternative electrolyte salt, and the thionyl chloride and the pretreatment component are treated separately, the additive is one or more of sulfur dioxide, polyvinyl chloride, bromine chloride and vinyl chloride-vinylidene chloride copolymer, the alternative electrolyte salt is halogen borate, LiGaC l4 and Li2B 10 Cl 10This lithium-thionyl chloride battery electrolyte helps reduce the corrosive and irritating effects of thionyl chloride on workers and the environmental pollution it causes. By adjusting the concentration of a suitable lithium tetrachloroaluminate electrolyte salt, adopting a suitable ratio of alternative electrolyte salts, and adding additives to the battery electrolyte, the voltage hysteresis of the lithium-thionyl chloride battery is effectively improved. However, this electrolyte does not effectively address the electrochemical performance of lithium / thionyl chloride batteries under high-temperature conditions, low-temperature conditions, and long-term storage passivation performance.

[0005] For example, patent document No. 201811570609.7 discloses a lithium / thionyl chloride battery electrolyte and a preparation method thereof. The electrolyte comprises thionyl chloride, an electrolyte salt, and an additive, wherein the additive comprises a first additive and a second additive. The first additive and the second additive in the electrolyte act synergistically to enable the lithium / thionyl chloride battery to achieve good discharge voltage and discharge capacity, significantly improving the voltage hysteresis phenomenon of the lithium / thionyl chloride battery, and the lithium / thionyl chloride battery prepared from the electrolyte has good cycle performance and high safety in use. However, the electrolyte does not effectively solve the problems of the electrochemical performance of the lithium / thionyl chloride battery in high temperature environment, the electrochemical performance in low temperature environment, and the long-term storage passivation performance. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a method for synthesizing a high-temperature lithium battery electrolyte additive. The additive prepared by this method can be used in lithium / thionyl chloride battery electrolyte to effectively improve the high and low temperature discharge performance of the battery, and can effectively improve the long-term storage performance of the lithium / thionyl chloride battery and the working safety in a high temperature environment.

[0007] The present invention adopts the following technical solution to solve the above technical problems, which is a method for synthesizing a high-temperature lithium battery electrolyte additive, characterized by the specific steps of: adding a metal halide to a solvent and heating it under reflux, wherein the metal halide is one or more of copper halide or aluminum halide, and the solvent is one or more of thionyl chloride or sulfuryl chloride, then adding polyvinyl halide powder and anhydrous lithium tetrachloroaluminate, continuing to heat and reflux until the solution color changes to yellow-green, stopping heating and naturally cooling to room temperature, and then filtering and drying to obtain the high-temperature lithium battery electrolyte additive.

[0008] It is further defined that the copper halide is one or more of copper chloride or copper bromide; the aluminum halide is one or more of aluminum chloride or aluminum bromide; and the polyvinyl halide is one or more of polyvinyl chloride or polyvinyl bromide.

[0009] It is further defined that the feeding ratio of the metal halide, solvent, polyvinyl halide powder and anhydrous lithium tetrachloroaluminate is 0.1~10g:100~2000mL:0.1~100g:10~200g.

[0010] It is further specified that the synthesis process is completed in a dry environment with a moisture content of ≤3%.

[0011] The high-temperature lithium battery electrolyte additive of the present invention is used for lithium / thionyl chloride battery electrolyte.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The high-temperature lithium battery electrolyte additive prepared by the present invention is used in lithium / thionyl chloride battery electrolyte to effectively improve the electrochemical performance of the battery in a high-temperature environment of 185~220℃, and can effectively improve the discharge voltage and discharge capacity of the battery in a high-temperature environment; (2) The high-temperature lithium battery electrolyte additive prepared by the present invention is used in lithium / thionyl chloride battery electrolyte to effectively improve the electrochemical performance of the battery in a low-temperature environment of -70~-35℃, and can effectively improve the discharge voltage and discharge capacity of the battery in a low-temperature environment; (3) The high-temperature lithium battery electrolyte additive prepared by the present invention is used in lithium / thionyl chloride battery electrolyte to effectively improve the long-term storage performance of the battery; (4) The high-temperature lithium battery electrolyte additive prepared by the present invention is used in lithium / thionyl chloride battery electrolyte to effectively improve the working safety of the battery in a high-temperature environment of 85~220℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the comparative test curve of 1# ER34615S with additives added at 200mA at an ambient temperature of 146℃.

[0014] Figure 2 This is the comparative test curve of 2# ER34615S with additive added at 400mA under ambient temperature of 146℃.

[0015] Figure 3 This is the comparative test curve of 3# ER34615S with additives added at 200mA at an ambient temperature of 23℃.

[0016] Figure 4 This is the comparative test curve of 4# ER34615S with additives added at 400mA at an ambient temperature of 23℃.

[0017] Figure 5 This is the comparative test curve of 5# ER34615S with additives added at 200mA at an ambient temperature of -40℃.

[0018] Figure 6 This is the comparative test curve of 6# ER34615S with additives added at 400mA at an ambient temperature of -40℃.

[0019] Figure 7This is the 200mA TMV curve of 5# ER34615S after being stored at an ambient temperature of 23℃ for one year.

[0020] Figure 8 This is the 400mA TMV curve of 6# ER34615S after being stored at an ambient temperature of 23℃ for one year. DETAILED DESCRIPTION

[0021] The above contents of the present invention are further described in detail below through examples, but this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above contents of the present invention fall within the scope of the present invention. Example 1

[0022] 1g of aluminum chloride was added to 300mL of thionyl chloride and heated under reflux for 40 minutes. 10g of polyvinyl chloride and 50g of anhydrous lithium tetrachloroaluminate were then added. Heating and reflux were continued until the solution turned amber-green. Heating was stopped and the solution was allowed to cool naturally to room temperature. The solution was then filtered (using a 40μm sand filter) and dried to obtain a high-temperature lithium battery electrolyte additive, which was then sealed for later use. The entire synthesis process was completed in a dry environment with a moisture content of ≤3%. 2wt% of the high-temperature lithium battery electrolyte additive was added to the electrolyte solution and injected into a lithium / thionyl chloride battery, which was sealed. The finished battery cells were aged in an aging oven at 45-55°C for 16 hours. From the same batch, ER34615S batteries 1#, 2#, 3#, 4#, 5#, and 6# were obtained.

[0023] Figure 1 The following curves compare the test results of a #1 ER34615S battery with the additive at 200mA at an ambient temperature of 146°C. The red curve represents a normal reference ER34615S battery, while the black curve represents an ER34615S battery with the additive. The figure shows that the ER34615S battery with the additive, at 200mA continuous discharge at 146°C, has a capacity 500mAh greater than that of a standard ER34615S battery. The overall platform voltage is approximately 0.1V higher, and the capacity release rate on the first discharge platform reaches 92.6% of the total capacity, 4000mAh more than the first platform capacity of a standard battery.

[0024] Figure 2The following are comparative test curves for a #2 ER34615S battery with the additive added at 400mA at an ambient temperature of 146°C. The red curve represents a normal reference ER34615S battery, while the black curve represents an ER34615S battery with the additive added. The figure shows that the ER34615S battery with the additive added, at 400mA continuous discharge at 146°C, has a capacity 1000mAh greater than that of a standard ER34615S battery. The overall platform voltage is approximately 0.08V higher, and the capacity release rate on the first discharge platform reaches 74% of the total capacity, which is 2800mAh greater than the first platform capacity of a standard battery.

[0025] Depend on Figure 1 and Figure 2 It can be seen that: (1) After adding the additive, the ER34615S battery is continuously discharged at 200mA at an ambient temperature of 146°C. The first high platform voltage continuous capacity is about 4000mAh higher than that of the normal battery, and the duration is about 20h longer; (2) After adding the additive, the ER34615S battery is continuously discharged at 200mA at an ambient temperature of 146°C. The overall platform voltage is about 0.1V higher; (3) After adding the additive, the ER34615S battery is continuously discharged at 200mA at an ambient temperature of 146°C. The battery capacity is about 500mAh higher. ; (4) After adding the additive, the ER34615S battery was continuously discharged at 400mA at an ambient temperature of 146℃. The first high platform voltage continuous capacity was about 2500mAh higher than that of the normal battery, and the duration was about 6h longer; (4) After adding the additive, the ER34615S battery was continuously discharged at 400mA at an ambient temperature of 146℃. The overall platform voltage was about 0.08V higher; (5) After adding the additive, the ER34615S battery was continuously discharged at 200mA at an ambient temperature of 146℃, and the battery capacity was about 1000mAh higher.

[0026] Figure 3 The following curves compare the performance of a #3 ER34615S battery with the additive at 200mA at an ambient temperature of 23°C. The red curve represents a normal reference ER34615S battery, while the black curve represents an ER34615S battery with the additive. The figure shows that the ER34615S battery with the additive exhibits a capacity 1000mAh greater than that of a standard ER34615S battery at 200mA continuous discharge at 23°C, and its overall platform voltage is approximately 0.08V higher.

[0027] Figure 4The following curves compare the test results of a #4 ER34615S battery with the additive at 400mA at an ambient temperature of 23°C. The red curve represents a normal reference ER34615S battery, while the black curve represents an ER34615S battery with the additive. As can be seen from the figure, the ER34615S battery with the additive exhibits a capacity 1000mAh greater than the standard ER34615S battery during a continuous discharge at 400mA at 23°C, and the overall plateau voltage is approximately 0.05V higher.

[0028] Depend on Figure 3 and Figure 4 It can be seen that: (1) the ER34615S battery after adding the additive is continuously discharged at 200mA at an ambient temperature of 23℃, and the platform voltage is about 0.08V higher than that of the normal ER34615S battery; (2) the ER34615S battery after adding the additive is continuously discharged at 200mA at an ambient temperature of 23℃, and the capacity is about 1000mAh higher than that of the normal ER34615S battery; (3) the ER34615S battery after adding the additive is continuously discharged at 400mA at an ambient temperature of 23℃, and the platform voltage is about 0.05V higher than that of the normal ER34615S battery; (4) the ER34615S battery after adding the additive is continuously discharged at 400mA at an ambient temperature of 23℃, and the capacity is about 1000mAh higher than that of the normal ER34615S battery.

[0029] Figure 5 The following curves compare the test results of a 5# ER34615S battery with the additive at 200mA at -40°C. The red curve represents a normal reference ER34615S battery, while the black curve represents an ER34615S battery with the additive. As can be seen from the figure, the ER34615S battery with the additive exhibits a capacity 3500mAh greater than the standard ER34615S battery during a continuous discharge at 200mA at -40°C, and the overall platform voltage is approximately 0.15V higher.

[0030] Figure 6 The following curves compare the test results of a #6 ER34615S battery with the additive at 400mA at -40°C. The red curve represents a normal reference ER34615S battery, while the black curve represents an ER34615S battery with the additive. As can be seen from the figure, the ER34615S battery with the additive exhibits a capacity 3000mAh greater than the standard ER34615S battery during a continuous discharge at 400mA at -40°C, and the overall platform voltage is approximately 0.15V higher.

[0031] Depend on Figure 5 and Figure 6It can be seen that: (1) the ER34615S battery after adding the additive is continuously discharged at 200mA at an ambient temperature of -40℃, and the platform voltage is about 0.15V higher than that of the normal ER34615S battery; (2) the ER34615S battery after adding the additive is continuously discharged at 200mA at an ambient temperature of -40℃, and the capacity is about 3500mAh higher than that of the normal ER34615S battery; (3) the ER34615S battery after adding the additive is continuously discharged at 400mA at an ambient temperature of 23℃, and the platform voltage is about 0.15V higher than that of the normal ER34615S battery; (4) the ER34615S battery after adding the additive is continuously discharged at 400mA at an ambient temperature of 23℃, and the capacity is about 3000mAh higher than that of the normal ER34615S battery; (5) the discharge capacity of the ER34615S battery after adding the additive at an ambient temperature of -40℃ is doubled.

[0032] Figure 7 This is the 200mA TMV curve of 5# ER34615S battery after being stored at an ambient temperature of 23℃ for one year. The red curve is the normal reference ER34615S battery; the black curve is the ER34615S battery with additives. Figure 8 This is the 400mA TMV curve of 6#ER34615S battery after being stored at an ambient temperature of 23℃ for one year. The red curve is the normal reference ER34615S battery; the black curve is the ER34615S battery with additives.

[0033] Depend on Figure 7 and Figure 8 It can be seen that: (1) After the ER34615S battery with additives is stored at an ambient temperature of 23℃ for one year, the TMV value of the 200mA test is about 1.0V higher than that of the normal battery, the voltage recovered at the end of 5s is about 0.1V higher than that of the normal battery, and the TMV voltage recovery speed is faster; (2) After the ER34615S battery with additives is stored at an ambient temperature of 23℃ for one year, the TMV value of the 400mA test is about 2.0V higher than that of the normal battery, the voltage recovered at the end of 5s is about 0.2V higher than that of the normal battery, and the TMV voltage recovery speed is faster.

[0034] In summary, the additive prepared in this embodiment can be used in the electrolyte of lithium / thionyl chloride batteries to effectively improve the electrochemical performance reliability of the battery in a high-temperature environment; the high-power performance operating voltage of the lithium / thionyl chloride battery is increased by more than 0.1V; the low-temperature operating performance of the lithium / thionyl chloride battery is extended to normal operation at -65°C, and the -40°C performance of 200mA / 400mA is improved by 20%-40%; after the lithium / thionyl chloride battery is stored at an ambient temperature of 23°C for one year, the TMV of the lithium / thionyl chloride battery with the additive at 200mA / 400mA is higher than that of the conventional battery, with the 200mA TMV being approximately 1.0V higher and the 400mA TMV being approximately 2.0V higher.

[0035] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for synthesizing a high-temperature lithium battery electrolyte additive, characterized in that The specific steps are: adding a metal halide to a solvent and heating it under reflux, wherein the metal halide is one or more of a copper halide or an aluminum halide, and the solvent is one or more of thionyl chloride or sulfuryl chloride, then adding polyvinyl halide powder and anhydrous lithium tetrachloroaluminate, continuing to heat and reflux until the solution changes to yellow-green, stopping heating and naturally cooling to room temperature, and then filtering and drying to obtain a high-temperature lithium battery electrolyte additive.

2. The method for synthesizing a high-temperature lithium battery electrolyte additive according to claim 1, characterized in that: The copper halide is one or more of copper chloride or copper bromide; the aluminum halide is one or more of aluminum chloride or aluminum bromide; and the polyvinyl halide is one or more of polyvinyl chloride or polyvinyl bromide.

3. The method for synthesizing a high-temperature lithium battery electrolyte additive according to claim 1, characterized in that: The feeding ratio of the metal halide, the solvent, the polyvinyl halide powder and the anhydrous lithium tetrachloroaluminate is 0.1-10 g: 100-2000 mL: 0.1-100 g: 10-200 g.

4. The method for synthesizing a high-temperature lithium battery electrolyte additive according to claim 1, characterized in that: The synthesis process was completed in a dry environment with a moisture content of ≤3%.

5. Use of the high-temperature lithium battery electrolyte additive prepared by the method according to any one of claims 1 to 4 in lithium / thionyl chloride battery electrolyte.

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