Preparation system and preparation method of lithium-thionyl chloride battery electrolyte

Abstract

The invention provides a lithium-thionyl chloride battery electrolyte preparation system and method, and the system comprises a stock solution storage and conveying module which comprises a thionyl chloride barrel, a stock solution conveying pump and a solution preparation pipeline system, the inlet of the stock solution conveying pump is communicated with the thionyl chloride barrel, and the outlet of the stock solution conveying pump is communicated with the feed inlet of a return tank through the solution preparation pipeline system; according to the invention, the totally-enclosed lithium-thionyl chloride battery electrolyte preparation system is constructed, and positive-pressure dehumidification air supply and negative-pressure exhaust safety protection are combined, so that moisture invasion and harmful gas leakage are effectively prevented, and the safety of the preparation process and the purity stability of the electrolyte are remarkably improved; and an automatically-controlled circulating reflux mixing and temperature-controlled heating process is adopted, so that the impurity removal efficiency is improved, the corrosion risk of the lithium anode is reduced, the traditional process is simplified, the production period is shortened, and the preparation requirements of large-scale high-quality electrolyte are met.

Description

Technical Field

[0001] This invention belongs to the field of electrolyte preparation technology, specifically relating to a preparation system and method for lithium-thionyl chloride battery electrolyte. Background Technology

[0002] Lithium-thionyl chloride (Li-SOCl2) batteries are high-energy-density primary electrochemical batteries, with an energy density reaching 700 Wh / kg. They possess advantages such as a wide operating temperature range (-60℃ to 150℃), low self-discharge rate, and long storage life (exceeding 10 years), making them widely used in military equipment, smart instruments, IoT sensors, and emergency power supplies. The electrolyte for these batteries is typically prepared using thionyl chloride (SOCl2) as a solvent, combined with a certain proportion of lithium salt. Through the delivery, mixing, and purification of high-purity stock solution, an electrolyte with high stability and low impurity content is obtained, ensuring the battery's stable performance under long-term storage and high-temperature environments.

[0003] However, existing electrolyte preparation processes generally suffer from the following drawbacks: First, SOCl2 is highly sensitive to moisture; even trace amounts of moisture can trigger decomposition, producing HCl and SO2 gases, leading to a decline in electrolyte performance. Traditional bottle dispensing and manual refilling require frequent opening, easily introducing moisture and impurities, making it difficult to guarantee high electrolyte purity. Second, impurity metal ions (such as Fe and Cu) are difficult to completely remove during preparation, especially since some processes rely on distillation for impurity removal. However, distillation is cumbersome, energy-intensive, and fails to eliminate acidic byproducts, affecting electrolyte stability and battery life. Third, traditional stirring methods are mostly simple mechanical stirring, resulting in uneven mixing, ineffective impurity removal, and a lack of synergistic effects from dynamic circulation and heating processes, leading to poor purification. Fourth, existing processes are mostly manual, resulting in low production efficiency and poor batch-to-batch consistency, making large-scale stable mass production difficult. Furthermore, SOCl2 is highly corrosive and toxic; traditional open operations not only pose a high risk of leakage but also lack efficient closed-loop dehumidification protection systems, failing to provide a safe and reliable production environment for electrolyte purification and storage. Summary of the Invention

[0004] This invention provides a preparation system and method for lithium-thionyl chloride battery electrolyte, which solves the problems mentioned in the background art of low efficiency, poor impurity control, high water content risk, poor batch consistency and insufficient safety in the existing lithium-thionyl chloride battery electrolyte preparation process.

[0005] The technical solution adopted in this invention is: a preparation system for a lithium-thionyl chloride battery electrolyte, comprising: The raw material storage and transportation module includes a thionyl chloride tank, a raw material transportation pump and a liquid distribution pipeline system. The inlet of the raw material transportation pump is connected to the thionyl chloride tank, and the outlet is connected to the feed port of the reflux tank through the liquid distribution pipeline system. It is used to send the thionyl chloride raw material into the reflux tank under the dry protective atmosphere provided by the positive pressure dehumidification air outlet. The reflux mixing and purification module includes a reflux tank, a reflux pump, a reflux pipeline on / off valve, and a temperature display. The outlet of the reflux tank is connected to the reflux pipeline on / off valve through the reflux pump to form a circulation pipeline, which is used to circulate and mix the thionyl chloride stock solution and lithium salt in the reflux tank and purify them by contacting lithium metal. The temperature control module includes a heating and cooling oil pipeline system and a temperature sensing component. The heating and cooling oil pipeline system is connected to the reflux tank for heat exchange and is used to heat the mixed electrolyte during the purification process and cool it after the purification is completed. The sulfur treatment and finished product output module includes a sulfur tank, a sulfur dioxide tank, a sulfur pipeline and a sulfur dioxide input on / off valve. The return sulfur tank is connected to the sulfur tank through a return pipeline and a delivery on / off valve. The sulfur dioxide tank is connected to the sulfur tank through a sulfur pipeline and a sulfur dioxide input on / off valve. The outlet on / off valve of the sulfur tank is used to output the finished electrolyte after sulfur treatment. The safety protection module includes an operation box, a positive pressure dehumidification air outlet, an operation box exhaust port, and inlet and exhaust valves, which are used to maintain internal positive pressure dry gas and prevent SOCl2 leakage.

[0006] It also includes a pipeline control module, which includes a raw liquid input on / off valve, an electro-hydraulic pipeline delivery on / off valve, a discharge on / off valve, an electro-hydraulic feed valve, and an electro-hydraulic pipeline input on / off valve. The pipeline control module is respectively installed on the pipeline between the liquid distribution pipeline system, the reflux tank, and the sulfur tank, and is used to switch the raw liquid flow direction, feed, and discharge path according to the predetermined process flow.

[0007] The positive pressure dehumidification air outlet is connected to a dry air source, which can provide dry inert gas with a dew point not higher than -40℃ and a temperature not higher than 25℃ to maintain a dry environment inside the operating box.

[0008] The liquid preparation pipeline system uses polytetrafluoroethylene (PTFE) pipelines, and the raw liquid transfer pump is a diaphragm pump or a magnetic pump.

[0009] The reflux tank and the sulfur-passing tank can be configured in two or more sets in parallel to achieve simultaneous purification and sulfur-passing treatment of multiple batches of electrolyte.

[0010] This invention also provides a method for preparing a lithium-thionyl chloride battery electrolyte, applied to the above-mentioned preparation system, comprising the following steps: Step 1: Under the dry and protective atmosphere provided by the positive pressure dehumidification air outlet, start the raw material delivery pump and deliver the thionyl chloride raw material to the return tank through the liquid distribution pipeline system and the raw material input on / off valve. Step 2: Add lithium salt to the reflux tank in proportion, and use the reflux pump and reflux pipeline opening and closing valve to form a reflux loop for circulation mixing; Step 3: During the mixing process, lithium metal is added to the reflux tank for purification; Step 4: Heat the mixed electrolyte to the set temperature through the heating and cooling oil pipeline system, and cool it after purification is completed; Step 5: Open the electro-hydraulic pipeline delivery valve to deliver the cooled electrolyte to the sulfur tank, and inject sulfur dioxide through the sulfur dioxide input valve. Step 6: After the sulfuring process is completed, the electrolyte is introduced into the storage tank for sealed storage through the finished product electro-hydraulic on / off valve and filter assembly.

[0011] The dew point of the dry protective atmosphere in step one is not higher than -40°C and the temperature is not higher than 25°C.

[0012] In step three, the lithium metal is added over a period of 8-16 hours to reduce the content of acidic impurities in the electrolyte.

[0013] The heating reaction in step four is carried out at a temperature range of 40-60°C, and after cooling to below 25°C, the process proceeds to step five.

[0014] The amount of sulfur dioxide introduced in step five is 0.5-3 wt% based on the mass of the mixed electrolyte.

[0015] The beneficial effects of this invention are as follows: This invention constructs a fully enclosed lithium-thionyl chloride battery electrolyte preparation system, combining positive pressure dehumidification and air supply with negative pressure exhaust for safety protection. This effectively prevents moisture intrusion and harmful gas leakage, significantly improving the safety of the preparation process and the purity and stability of the electrolyte. Furthermore, the use of automated controlled circulating reflux mixing and temperature-controlled heating processes not only improves the efficiency of impurity removal and reduces the risk of lithium anode corrosion, but also simplifies traditional processes, shortens the production cycle, and meets the needs of large-scale, high-quality electrolyte preparation.

[0016] This invention supports multi-channel parallel purification processing, improving production capacity and batch consistency. The finished electrolyte is directly transported, stored, and injected through a closed pipeline, avoiding the contamination risks associated with manual operation and ensuring the performance stability and long-term reliability of battery products. The overall process is safe, efficient, and environmentally friendly, possessing significant value for widespread application. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0018] in: 1. Thionyl chloride tank; 2. Raw material transfer pump; 3. Liquid preparation pipeline system; 4. Positive pressure dehumidification air outlet; 5. Control box; 6. Feed inlet; 7. Exhaust valve one; 8. Return pipeline on / off valve one; 9. Temperature display; 10. Raw material input on / off valve; 11. Return pipeline on / off valve two; 12. Electro-hydraulic pipeline transfer on / off valve; 13. Heating and cooling oil pipeline system; 14. Return pipeline on / off valve three; 15. Return pump; 16. Drainage on / off valve; 17. Finished product electro-hydraulic on / off valve; 18. Sulfur dioxide input on / off valve; 19. Exhaust valve two; 20. Electro-hydraulic feed valve; 21. Control box exhaust port; 22. Electro-hydraulic pipeline input on / off valve; 23. Sulfur dioxide tank; 24. Return tank; 25. Sulfur passage tank. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] As shown in the figure, a system for preparing a lithium-thionyl chloride battery electrolyte includes: The raw material storage and transportation module includes a thionyl chloride tank 1, a raw material transportation pump 2, and a liquid preparation pipeline system 3. The thionyl chloride tank 1 is used to store high-purity SOCl2 raw material, and its outlet is connected to the liquid preparation pipeline system 3 through the raw material transportation pump 2. The raw material transportation pump 2 is preferably a diaphragm pump or a magnetic pump, which has anti-leakage and anti-corrosion properties and is suitable for transporting SOCl2. The liquid preparation pipeline system 3 is made of polytetrafluoroethylene to avoid SOCl2 reacting with the pipeline or adsorbing impurities.

[0021] The module's outlet is connected to the inlet 6 of the return tank 24 via a pipeline. Under the protection of a dry inert gas with a dew point not higher than -40℃ and a temperature not higher than 25℃ provided by the positive pressure dehumidification air outlet 4, the SOCl2 raw liquid is transported to the return tank 24.

[0022] The reflux mixing and purification module includes a reflux tank 24, a reflux pump 15, reflux pipeline on / off valves, and a temperature display 9. The reflux pipeline on / off valves include a first reflux pipeline on / off valve 8, a second reflux pipeline on / off valve 11, and a third reflux pipeline on / off valve 14. The first reflux pipeline on / off valve 8 is arranged on the upward reflux branch pipe led out from the liquid outlet side of the reflux pump 15. The second reflux pipeline on / off valve 11 is arranged on the branch pipe between the liquid outlet side of the reflux pump 15 and the reflux port on the side wall of the reflux tank 24. The third reflux pipeline on / off valve 14 is installed on the connecting pipe between the liquid outlet at the bottom of the reflux tank 24 and the suction side of the reflux pump 15. The outlet of the reflux tank 24 is connected to the reflux pipeline opening and closing valve via the reflux pump 15 to form a circulation pipeline, which is used to circulate and mix the thionyl chloride stock solution and lithium salt in the reflux tank 24 and purify them by contacting lithium metal. The reflux tank 24 is used to receive the SOCl2 stock solution and forms a circulation loop with the reflux pump 15 through the feed port 6 and the reflux pipeline opening and closing valve to realize dynamic reflux stirring of the liquid. The reflux pump 15 draws the mixture out from the outlet of the reflux tank 24 and sends it back to the top of the reflux tank 24 through the reflux pipeline, thereby forming a circulating mixture. Lithium salt can be added to the reflux tank 24 in proportion, and lithium metal (such as lithium strip or lithium sheet) can be added during the mixing process. Through contact reaction with the SOCl2 stock solution, acidic impurities in the electrolyte are removed. The temperature display 9 monitors the liquid temperature in the reflux tank 24 in real time, which facilitates the adjustment of process parameters.

[0023] The temperature control module includes a heating and cooling oil pipeline system 13 and a temperature sensing component. The heating and cooling oil pipeline system 13 is heat-exchange connected to the reflux tank 24 and is used to heat the mixed electrolyte during the purification process and cool it afterward. During the purification process, the mixed electrolyte is heated, with the preferred reaction temperature being 40℃-60℃ to promote a full reaction between lithium metal and acidic impurities. After purification, the oil pipeline system switches to cooling mode, cooling the mixed electrolyte to below 25℃ to prepare for subsequent sulfurization treatment.

[0024] The sulfur treatment and finished product output module includes a sulfur tank 25, a sulfur dioxide tank 23, a sulfur pipeline, and a sulfur dioxide input on / off valve 18. The return sulfur tank 24 is connected to the sulfur tank 25 through a return pipeline and a delivery on / off valve (here, the delivery on / off valve includes an electro-hydraulic pipeline delivery on / off valve 12 and an electro-hydraulic pipeline input on / off valve 22). The sulfur dioxide tank 23 is connected to the sulfur tank 25 through a sulfur pipeline and a sulfur dioxide input on / off valve 18. Specifically, a valve is also installed on the sulfur pipeline at the output end of the sulfur dioxide tank 23. When this valve and the sulfur dioxide input on / off valve 18 are opened simultaneously, sulfur dioxide can enter the sulfur tank 25. The outlet on / off valve of the sulfur tank 25 is used to output the finished electrolyte after sulfur treatment.

[0025] The safety protection module includes an operation box 5, a positive pressure dehumidification air outlet 4, an operation box exhaust port 21, and inlet and exhaust valves. The inlet valve is located at the positive pressure dehumidification air outlet 4, and the exhaust valve (a negative pressure exhaust valve) is located at the operation box exhaust port 21. The operation box 5 encloses the above modules and is equipped with the inlet and exhaust valves to maintain internal positive pressure dry gas and prevent SOCl2 leakage. Specifically, the reflux mixing and purification module, temperature control module, and sulfur treatment and finished product output module are located inside the operation box 5. To further improve safety, there is an exhaust valve 7 on the reflux tank 24 and an exhaust valve 19 installed on the sulfur tank 25.

[0026] The system also includes a pipeline control module, which includes a raw liquid input on / off valve 10, an electro-hydraulic pipeline delivery on / off valve 12, a discharge on / off valve 16, an electro-hydraulic feed valve 20, and an electro-hydraulic pipeline input on / off valve 22. The pipeline control module is respectively installed on the pipeline between the liquid distribution pipeline system 3, the reflux tank 24, and the sulfur tank 25, and is used to switch the raw liquid flow direction, feed, and discharge path according to the predetermined process flow.

[0027] The positive pressure dehumidification air outlet 4 is connected to a dry air source and can provide dry inert gas with a dew point not higher than -40℃ and a temperature not higher than 25℃ to maintain a dry environment inside the operating box 5.

[0028] The liquid distribution pipeline system 3 uses polytetrafluoroethylene (PTFE) pipelines, and the raw liquid transfer pump 2 is a diaphragm pump or a magnetic pump.

[0029] The reflux tank 24 and the sulfur-passing tank 25 can be configured in two or more sets in parallel to achieve simultaneous purification and sulfur-passing treatment of multiple batches of electrolyte.

[0030] This embodiment also provides a method for preparing a lithium-thionyl chloride battery electrolyte, applied to the above-mentioned preparation system, including the following steps: Step 1 (Feeding / Protection): Under the dry and inert protective atmosphere provided by the positive pressure dehumidification air outlet 4, start the raw material transfer pump 2, and transport the SOCl2 raw material to the return tank 24 through the liquid distribution pipeline and the raw material input on / off valve 10. The dew point of the dry protective atmosphere is not higher than -40℃ and the temperature is not higher than 25℃.

[0031] Step 2 (Lithium Salt Addition / Circulation Mixing): Add lithium salt to reflux tank 24 in proportion; open reflux pipeline on / off valve 3 14 and at least one (reflux pipeline on / off valve 1 8 and 2) to form a circulation, start reflux pump 15 to circulate and mix the liquid in the tank until the lithium salt is fully dissolved.

[0032] Step 3 (Lithium Metal Purification): During the circulation process, lithium metal (strips, flakes, or scraps are all acceptable) is added to the tank for 8 to 16 hours, preferably 12 hours, to reduce the content of acidic impurities in the electrolyte.

[0033] Step 4 (Heating Purification / Cooling Switch): Heat the system inside the tank to 40–60°C using the heating oil circuit and maintain this temperature to promote the reaction; the reaction endpoint can be determined by combining acidity indicators, online conductivity, or sample analysis. Then switch to the cooling oil circuit to cool the system to below 25°C.

[0034] Step 5 (Sulfurization): Close reflux pipeline valves 1 and 2, keeping valve 3 open; open electro-hydraulic pipeline delivery valve 12, and reflux pump 15 will send the cooled electrolyte into sulfurization tank 25. Open sulfur dioxide input valve 18, and add SO2 at a dosage of 0.5–3 wt% of the electrolyte mass to perform sulfurization treatment.

[0035] Step 6 (Filtration / Finished Product Storage): After sulfuring is completed, turn off the SO2 input; open the finished product electro-hydraulic on / off valve 17 to allow the electrolyte to enter the sealed storage tank through the online filtration assembly and obtain the finished electrolyte.

[0036] In existing technologies, impurities are often removed by distillation, but distillation equipment is complex, energy-intensive, and cumbersome to operate. In this embodiment, high-purity SOCl2 stock solution is used directly to avoid the distillation process, which greatly simplifies the process flow and equipment configuration.

[0037] This embodiment uses a multi-mode circulation loop formed by a reflux pump and a reflux pipeline on / off valve to create a highly efficient circulation flow of liquid within the tank. Compared to mechanical stirring, this results in a more uniform mixing effect and eliminates the risk of leakage from the stirring shaft seal.

[0038] In this embodiment, the mixture is heated to 40-60°C during the reflux process by heating the oil circuit system, which promotes the reaction rate and completeness of lithium metal and acidic impurities, resulting in higher electrolyte purity.

[0039] This embodiment omits equipment such as distillation columns, resulting in a compact overall system structure, smaller footprint, reduced energy consumption, and shorter production cycle, making it more suitable for modern continuous / batch preparation of high-purity SOCl2 as raw material.

[0040] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for preparing a lithium-thionyl chloride battery electrolyte, characterized in that, include: The raw material storage and transportation module includes a thionyl chloride tank, a raw material transportation pump and a liquid distribution pipeline system. The inlet of the raw material transportation pump is connected to the thionyl chloride tank, and the outlet is connected to the feed port of the reflux tank through the liquid distribution pipeline system. It is used to send the thionyl chloride raw material into the reflux tank under the dry protective atmosphere provided by the positive pressure dehumidification air outlet. The reflux mixing and purification module includes a reflux tank, a reflux pump, a reflux pipeline on / off valve, and a temperature display. The outlet of the reflux tank is connected to the reflux pipeline on / off valve through the reflux pump to form a circulation pipeline, which is used to circulate and mix the thionyl chloride stock solution and lithium salt in the reflux tank and purify them by contacting lithium metal. The temperature control module includes a heating and cooling oil pipeline system and a temperature sensing component. The heating and cooling oil pipeline system is connected to the reflux tank for heat exchange and is used to heat the mixed electrolyte during the purification process and cool it after the purification is completed. The sulfur treatment and finished product output module includes a sulfur tank, a sulfur dioxide tank, a sulfur pipeline and a sulfur dioxide input on / off valve. The return sulfur tank is connected to the sulfur tank through a return pipeline and a delivery on / off valve. The sulfur dioxide tank is connected to the sulfur tank through a sulfur pipeline and a sulfur dioxide input on / off valve. The outlet on / off valve of the sulfur tank is used to output the finished electrolyte after sulfur treatment. The safety protection module includes an operation box, a positive pressure dehumidification air outlet, an operation box exhaust port, and inlet and exhaust valves, which are used to maintain internal positive pressure dry gas and prevent SOCl2 leakage.

2. The preparation system for a lithium-thionyl chloride battery electrolyte according to claim 1, characterized in that, It also includes a pipeline control module, which includes a raw liquid input on / off valve, an electro-hydraulic pipeline delivery on / off valve, a discharge on / off valve, an electro-hydraulic feed valve, and an electro-hydraulic pipeline input on / off valve. The pipeline control module is respectively installed on the pipeline between the liquid distribution pipeline system, the reflux tank, and the sulfur tank, and is used to switch the raw liquid flow direction, feed, and discharge path according to the predetermined process flow.

3. The preparation system for a lithium-thionyl chloride battery electrolyte according to claim 1, characterized in that, The positive pressure dehumidification air outlet is connected to the dry air source, which can provide dry inert gas with a dew point not higher than -40℃ and a temperature not higher than 25℃ to maintain a dry environment inside the operating box.

4. The preparation system for a lithium-thionyl chloride battery electrolyte according to claim 1, characterized in that, The liquid preparation pipeline system uses polytetrafluoroethylene (PTFE) pipelines, and the raw liquid transfer pump is a diaphragm pump or a magnetic pump.

5. The preparation system for a lithium-thionyl chloride battery electrolyte according to claim 1, characterized in that, The reflux tank and the sulfur-passing tank can be configured in two or more sets in parallel to achieve simultaneous purification and sulfur-passing treatment of multiple batches of electrolyte.

6. A method for preparing a lithium-thionyl chloride battery electrolyte, characterized in that, The preparation system described in any one of claims 1-5 comprises the following steps: Step 1: Under the dry and protective atmosphere provided by the positive pressure dehumidification air outlet, start the raw material delivery pump and deliver the thionyl chloride raw material to the return tank through the liquid distribution pipeline system and the raw material input on / off valve. Step 2: Add lithium salt to the reflux tank in proportion, and use the reflux pump and reflux pipeline opening and closing valve to form a reflux loop for circulation mixing; Step 3: During the mixing process, lithium metal is added to the reflux tank for purification; Step 4: Heat the mixed electrolyte to the set temperature through the heating and cooling oil pipeline system, and cool it after purification is completed; Step 5: Open the electro-hydraulic pipeline delivery valve to deliver the cooled electrolyte to the sulfur tank, and inject sulfur dioxide through the sulfur dioxide input valve. Step 6: After the sulfuring process is completed, the electrolyte is introduced into the storage tank for sealed storage through the finished product electro-hydraulic on / off valve and filter assembly.

7. The method for preparing a lithium-thionyl chloride battery electrolyte according to claim 1, characterized in that, In step one, the dew point of the dry protective atmosphere should not exceed -40°C, and the temperature should not exceed 25°C.

8. The method for preparing a lithium-thionyl chloride battery electrolyte according to claim 1, characterized in that, In step three, the lithium metal is added over a period of 8-16 hours to reduce the content of acidic impurities in the electrolyte.

9. The method for preparing a lithium-thionyl chloride battery electrolyte according to claim 1, characterized in that, The heating reaction in step four is carried out at a temperature range of 40-60°C, and after cooling to below 25°C, it proceeds to step five.

10. The method for preparing a lithium-thionyl chloride battery electrolyte according to claim 1, characterized in that, The amount of sulfur dioxide introduced in step five is 0.5-3 wt% based on the mass of the mixed electrolyte.

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