Parameter control method for production of high-purity lithium battery electrolyte

Abstract

The invention discloses a parameter control method for production of a high-purity lithium battery electrolyte, which comprises the following steps of: pretreating raw materials, namely treating a lithium salt, an organic solvent and an additive; meanwhile, the raw materials are subjected to vacuum drying treatment; in the electrolyte synthesis reaction process, the reaction temperature is set according to different reaction stages, and the temperature is controlled within a preset temperature range; adjusting the pressure in the reaction kettle according to the reaction stages of different time periods, and controlling the pressure within a preset pressure range; different stirring speeds are set in different reaction stages, so that the materials are uniformly mixed; removing residual moisture and small molecular impurities by using a molecular sieve adsorption device; and performing quality detection on the finished product, and performing feedback adjustment on production process parameters according to a detection result. The raw materials are pretreated to guarantee the purity, the reaction conditions are controlled to guarantee the purity of the electrolyte, and the purity is improved by means of removing impurities; reasonable parameter setting improves efficiency, reduces cost, stabilizes parameters and saves equipment expenditure.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery electrolyte production, and in particular to a parameter control method for producing high-purity lithium battery electrolyte. Background Art

[0002] As the global demand for clean energy and high-performance energy storage equipment grows rapidly, lithium batteries have become the preferred energy storage solution in many fields due to their excellent characteristics such as high energy density, long cycle life, and low self-discharge rate. In the field of electric vehicles, the performance of lithium batteries is directly related to the vehicle's range, charging time, and overall safety; in mobile electronic devices such as smartphones and tablets, the quality of lithium batteries significantly affects the device's service life, charging efficiency, and stability under different environmental conditions; lithium battery electrolyte, as a key component of lithium batteries, plays a bridge role in conducting ions between the positive and negative electrodes. Its purity and performance play a decisive role in the electrochemical performance of lithium batteries. High-purity electrolytes can effectively reduce the internal resistance of the battery and reduce energy loss, thereby improving the battery's charge and discharge efficiency and power output. For example, during the fast charging process of electric vehicles, high-purity electrolytes can ensure that lithium ions migrate quickly and smoothly between the positive and negative electrodes, significantly shortening the charging time while reducing safety hazards caused by heat.

[0003] The lithium battery electrolyte production process in the prior art, on the one hand, has a wide range of raw materials and complex components. The trace metal ions, moisture, organic impurities, etc. that may be carried in the raw materials may cause a series of adverse reactions in the electrolyte even if the content is extremely low. For example, metal ions may catalyze the decomposition reaction of the electrolyte, resulting in an increase in battery capacity decay; moisture will react with lithium salts to generate corrosive substances, destroying the electrode structure and diaphragm integrity inside the battery, thereby seriously affecting the cycle life and safety of the battery; on the other hand, various process parameters in the production process, such as reaction temperature, pressure, stirring speed, etc., are intertwined and have extremely complex nonlinear effects on the purity and performance of the final product. Excessive reaction temperature may lead to thermal decomposition of raw materials or products and generate additional impurities; improper reaction pressure may affect the equilibrium conversion rate of the reaction, making the reaction incomplete, and residual reactants mixed into the electrolyte as impurities; unreasonable stirring speed may cause uneven mixing of materials, excessively high or too low local concentrations, triggering side reactions, and reducing the purity and stability of the electrolyte.

[0004] Although existing technologies have made some progress in the production of lithium battery electrolytes, it is still difficult to meet the increasingly stringent requirements of high purity and high performance. Therefore, there is an urgent need for an innovative, precise and efficient parameter control method that can accurately control the key parameters of each link in the entire production process, minimize the introduction of impurities, optimize the reaction process, and ensure that the produced lithium battery electrolyte has ultra-high purity and excellent performance stability, thereby providing solid technical support for the further development of the lithium battery industry. Summary of the invention

[0005] In view of the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is to provide a parameter control method for the production of high-purity lithium battery electrolyte that can effectively solve the above-mentioned technical defects.

[0006] To achieve the above object, the present invention provides a parameter control method for producing high-purity lithium battery electrolyte, comprising the following steps:

[0007] Pre-treating the raw materials, including the treatment of lithium salts, organic solvents and additives; and vacuum drying the raw materials;

[0008] During the electrolyte synthesis reaction, the reaction temperature is set according to different reaction stages and the temperature is controlled within a preset temperature range;

[0009] Adjust the pressure in the reactor according to the reaction stages at different times and control the pressure within a preset pressure range;

[0010] Set different stirring speeds at different stages of the reaction to ensure uniform mixing of materials;

[0011] Ion exchange resin columns are used to remove metal ion impurities, and molecular sieve adsorption devices are used to remove residual moisture and small molecular impurities;

[0012] Conduct quality inspection on finished products and make feedback adjustments to production process parameters based on the inspection results.

[0013] Furthermore, the raw material is pretreated by using a multi-stage filtration device to filter the raw material, with the filtration accuracy increasing in sequence to remove particulate impurities therein, and the multi-stage filtration includes primary filtration, secondary filtration and tertiary filtration, wherein the primary filtration uses a filter screen with a pore size of 5 microns, the secondary filtration uses a filter screen with a pore size of 3 microns, and the tertiary filtration uses an ultrafiltration membrane with a pore size of 0.5 microns;

[0014] The raw materials are vacuum dried with the drying temperature controlled between 60°C and 70°C for 3 to 5 hours to remove moisture and volatile impurities to ensure that the purity of the raw materials meets the preset standards.

[0015] Furthermore, the process of filtering the raw material using a multi-stage filtering device includes:

[0016] The first filtration uses a 5-micron pore size filter and calculates the first filtration efficiency E1:

[0017]

[0018] The secondary filtration uses a filter with a pore size of 3 microns, and the secondary filtration efficiency E2 is calculated as follows:

[0019]

[0020] The third filtration is performed using an ultrafiltration membrane with a pore size of 0.5 microns, and the third filtration efficiency E3 is calculated as follows:

[0021]

[0022] Wherein, C0 represents the impurity content of the initial particles of the raw material (unit: ppm);

[0023] C1 represents the particle impurity content after the first filtration (unit: ppm);

[0024] C2 represents the particle impurity content after secondary filtration (unit: ppm);

[0025] C3 represents the particle impurity content after three filtrations (unit: ppm);

[0026] E1 represents the first filtration efficiency;

[0027] E2 represents the filtration efficiency of the secondary filtration relative to the raw material after the first filtration;

[0028] E3 represents the filtration efficiency of the raw material after tertiary filtration relative to that after secondary filtration.

[0029] Furthermore, the vacuum drying of the raw materials specifically includes the following methods:

[0030] Control the drying temperature between 60℃ and 70℃, the drying time between 3 hours and 5 hours, and calculate the drying rate of the raw materials:

[0031]

[0032] Where R represents the drying rate;

[0033] M0 represents the initial moisture content of the raw material;

[0034] M1 represents the moisture content after drying.

[0035] Furthermore, the step of accurately setting the reaction temperature according to different reaction stages specifically includes:

[0036] During the synthesis reaction of the electrolyte, the reaction temperature is controlled to maintain the temperature in the reactor between 25°C and 35°C. The reaction temperature is monitored in real time by a temperature sensor and linked with the heating device and the cooling device through a feedback control system.

[0037] When the reaction temperature is higher than the set upper limit of 35°C, the cooling device is started to cool it down; when the reaction temperature is lower than the set lower limit of 25°C, the heating device is started to heat it up;

[0038] When the reaction temperature is controlled at 20°C, the reaction conversion rate is P1=60%; the product purity is Q1=98.5%; when the temperature is controlled at 30°C, the reaction conversion rate is P2=85%, and the product purity is Q2=99.5%.

[0039] Furthermore, adjusting the pressure in the reactor according to the reaction stages at different time periods specifically includes:

[0040] The pressure was gradually adjusted according to the reaction process and material status; in the initial stage of the reaction, the pressure in the reactor was set to 100 kPa, in the middle stage of the reaction, the pressure was adjusted to 150 kPa, and in the late stage of the reaction, the pressure was controlled at 200 kPa;

[0041] The pressure change is monitored in real time by a pressure sensor, and the pressure is maintained stable by a pressure regulating device. The pressure fluctuation is controlled within ±10kPa to promote the reaction equilibrium to move towards the production of high-purity electrolyte. When the pressure fluctuation exceeds ±20kPa, the impurity content in the electrolyte will increase by Z=50ppm. When controlled within ±10kPa, the impurity content can be stably controlled at 10ppm.

[0042] Furthermore, different stirring speeds are set at different stages of the reaction, and the specific setting method is as follows:

[0043] The stirring member used for stirring is a paddle-type stirring paddle. In the early stage of the reaction, the stirring speed is set to 90-110 rpm. As the reaction progresses, the stirring speed is increased to 190-210 rpm in the middle stage of the reaction and reduced to 140-160 rpm in the late stage of the reaction.

[0044] Furthermore, the use of an ion exchange resin column to remove metal ion impurities specifically includes:

[0045] Control the flow rate of the ion exchange resin column between 20 ml / min and 30 ml / min, and calculate the metal ion removal rate:

[0046]

[0047] In the formula, F represents the metal ion removal rate;

[0048] I0 represents the initial amount of metal ions;

[0049] I1 represents the amount of metal ions remaining after treatment.

[0050] Furthermore, the use of a molecular sieve adsorption device to remove residual moisture and small molecular impurities specifically includes the following steps:

[0051] Preparation

[0052] First, a molecular sieve with a pore size of 3 to 5 angstroms should be selected, and the selected molecular sieve should be installed in the adsorption device to ensure that the device is well sealed to prevent external impurities from entering and affecting the adsorption effect;

[0053] Adsorption operation

[0054] The electrolyte flows through the molecular sieve adsorption device at a flow rate of 20-30 ml / min to adsorb water molecules and small molecular impurities for a period of 2-4 hours, so that the water content in the electrolyte is less than 20 ppm and the small molecular impurity content is less than 5 ppm;

[0055] Post-adsorption treatment

[0056] When the adsorption of the molecular sieve decreases, the molecular sieve is regenerated to desorb the water and small molecular impurities adsorbed in the micropores of the molecular sieve, restore the adsorption performance of the molecular sieve, so that it can be used again, and the electrolyte after adsorption treatment is tested.

[0057] Furthermore, comprehensive quality testing of the finished lithium battery electrolyte products includes:

[0058] The test items include purity, conductivity, moisture content, and metal ion content. According to the test results, the parameters in the production process are adjusted. If the purity of the finished product does not meet the preset high purity standard, the corresponding parameters are fine-tuned by 10 times the purity deviation. According to the degree of deviation, if the purity deviation is within 0.1%, the parameter adjustment range is 1% of the original set value; if the purity deviation is within 0.2%, the parameter adjustment range is 2% of the original set value, and so on, forming a closed-loop control.

[0059] The present invention has the following beneficial effects:

[0060] 1) The present invention can effectively remove particulate impurities, moisture and volatile impurities in the raw materials by performing multi-stage filtration and vacuum drying on the raw materials, thereby ensuring the purity of the raw materials from the source and laying a foundation for the production of high-purity lithium battery electrolyte;

[0061] 2) During the electrolyte synthesis process, controlling the reaction temperature, pressure and stirring speed helps to carry out the reaction under optimal conditions and reduce the occurrence of side reactions caused by fluctuations in reaction conditions, thereby ensuring the high purity of the electrolyte;

[0062] 3) The use of ion exchange resin columns to remove metal ion impurities and molecular sieve adsorption devices to remove residual moisture and small molecule impurities further improves the purity of the electrolyte and ensures that the product quality meets high purity standards;

[0063] 4) Accurate parameter control helps to optimize the chemical composition and microstructure of the electrolyte, thereby improving the electrochemical performance of the lithium battery, such as improving the charge and discharge efficiency and cycle life of the battery. For example, the reaction temperature and stirring speed in the present invention can make the components in the electrolyte evenly mixed to form a more stable electrolyte system, which is beneficial to the transmission of lithium ions inside the battery, thereby improving the overall performance of the battery;

[0064] 5) Through the present invention, each key parameter in the production process is strictly and accurately controlled, from raw material pretreatment to electrolyte synthesis, impurity removal, and then to finished product testing and parameter adjustment, forming a complete and closed-loop control system, reducing the problem of unstable product quality caused by process parameter fluctuations, and ensuring the stability and reliability of the production process;

[0065] 6) Reasonable process parameter settings, such as setting appropriate temperature, pressure and stirring speed at different reaction stages, can speed up the reaction and shorten the production cycle. At the same time, through precise control of the production process, rework or scrapping due to unqualified product quality can be reduced, thus improving production efficiency;

[0066] 7) By pretreating the raw materials to remove impurities and moisture, it is possible to avoid the waste of raw materials caused by the adverse effects of impurities and moisture on the reaction, thereby improving the utilization rate of raw materials and reducing production costs;

[0067] 8) Stable production process parameters help reduce wear and failure of equipment during operation. For example, in the present invention, precisely controlled pressure and temperature can prevent equipment from being damaged due to excessive pressure or temperature, thereby extending the service life of the equipment and reducing equipment maintenance and replacement costs;

[0068] 9) During the production process, sensors are used to monitor key parameters in real time, and feedback and adjustment of production parameters are made based on the test results of finished products, forming an effective quality control mechanism that can promptly detect and correct deviations in the production process, ensuring that each batch of products can meet the quality standards of high purity and high performance;

[0069] 10) The present invention specifies in detail the various steps and parameters in the production process, so that the production process is highly standardized, which is convenient for production management and quality control, helps enterprises to establish a stable product quality system, and improves the market competitiveness of enterprises.

[0070] 11) Through pretreatment of raw materials and precise production process control, waste generated due to incomplete reaction or substandard product quality is reduced. At the same time, in the process of impurity removal, the waste generated (such as ion exchange resin regeneration waste and molecular sieve regeneration waste) is reasonably treated to reduce pollution to the environment;

[0071] 12) During the temperature control process, energy waste is reduced through reasonable heating and cooling strategies (such as automatically adjusting the heating / cooling device according to the reaction temperature). BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a flow chart of a parameter control method in an embodiment of the present application. DETAILED DESCRIPTION

[0073] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0074] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0075] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] like Figure 1 Shown

[0077] Example 1

[0078] A parameter control method for producing high-purity lithium battery electrolyte, characterized in that it comprises the following steps:

[0079] Pre-treating the raw materials, including the treatment of lithium salts, organic solvents and additives; vacuum drying the raw materials; filtering the raw materials with a multi-stage filtration device, with the filtration accuracy increasing in sequence, to remove particulate impurities therein, the multi-stage filtration includes primary filtration, secondary filtration and tertiary filtration, wherein the primary filtration uses a 5-micron pore size filter, the secondary filtration uses a 3-micron pore size filter, and the tertiary filtration uses a 0.5-micron pore size ultrafiltration membrane for filtration;

[0080] The raw materials are vacuum dried with the drying temperature controlled at 60°C and the drying time at 5 hours to remove moisture and volatile impurities and ensure that the purity of the raw materials meets the preset standards.

[0081] During the electrolyte synthesis reaction, the reaction temperature is set according to different reaction stages and the temperature is controlled within a preset temperature range;

[0082] The precise setting of the reaction temperature according to different reaction stages specifically includes:

[0083] During the synthesis reaction of the electrolyte, the reaction temperature is controlled to maintain the temperature in the reactor at 25°C. The reaction temperature is monitored in real time by a temperature sensor and linked with the heating device and the cooling device through a feedback control system.

[0084] When the reaction temperature is higher than the set upper limit of 35°C, the cooling device is started to cool it down; when the reaction temperature is lower than the set lower limit of 25°C, the heating device is started to heat it up;

[0085] When the reaction temperature is controlled at 20°C, the reaction conversion rate is P1=60%; the product purity is Q1=98.5%; when the temperature is controlled at 30°C, the reaction conversion rate is P2=85%, and the product purity is Q2=99.5%.

[0086] Adjust the pressure in the reactor according to the reaction stages at different times and control the pressure within a preset pressure range;

[0087] Set different stirring speeds at different stages of the reaction to ensure uniform mixing of materials;

[0088] Ion exchange resin columns are used to remove metal ion impurities, and molecular sieve adsorption devices are used to remove residual moisture and small molecular impurities;

[0089] Conduct quality inspection on finished products and make feedback adjustments to production process parameters based on the inspection results.

[0090] Adjusting the pressure in the reactor according to the reaction stages at different times specifically includes:

[0091] The pressure was gradually adjusted according to the reaction process and material status; in the initial stage of the reaction, the pressure in the reactor was set to 100 kPa, in the middle stage of the reaction, the pressure was adjusted to 150 kPa, and in the late stage of the reaction, the pressure was controlled at 200 kPa;

[0092] The pressure change is monitored in real time by a pressure sensor, and the pressure is maintained stable by a pressure regulating device. The pressure fluctuation is controlled within ±10kPa to promote the reaction equilibrium to move towards the production of high-purity electrolyte. When the pressure fluctuation exceeds ±20kPa, the impurity content in the electrolyte will increase by Z=50ppm. When controlled within ±10kPa, the impurity content can be stably controlled at 10ppm.

[0093] The use of a molecular sieve adsorption device to remove residual moisture and small molecule impurities specifically includes the following steps:

[0094] Preparation

[0095] First, a molecular sieve with a pore size of 3 to 5 angstroms is selected and the selected molecular sieve is installed in an adsorption device;

[0096] Adsorption operation

[0097] The electrolyte flows through the molecular sieve adsorption device at a flow rate of 20-30 ml / min to adsorb water molecules and small molecular impurities for a period of 2-4 hours, so that the water content in the electrolyte is less than 20 ppm and the small molecular impurity content is less than 5 ppm;

[0098] Post-adsorption treatment

[0099] When the adsorption of the molecular sieve decreases, the molecular sieve is regenerated to desorb the water and small molecular impurities adsorbed in the micropores of the molecular sieve, and the electrolyte after the adsorption treatment is tested.

[0100] Example 2

[0101] A parameter control method for producing high-purity lithium battery electrolyte, comprising the following steps:

[0102] The raw materials are pretreated to remove impurities therein, and the raw materials are vacuum dried to remove moisture and volatile impurities; more specifically:

[0103] The pretreatment of the raw materials includes the treatment of lithium salts, organic solvents and additives, specifically, filtering the raw materials with a multi-stage filtration device, with the filtration accuracy increasing in sequence, to remove particulate impurities therein, the multi-stage filtration includes primary filtration, secondary filtration and tertiary filtration, wherein the primary filtration uses a filter screen with a pore size of 5 microns, the secondary filtration uses a filter screen with a pore size of 3 microns, and the tertiary filtration uses an ultrafiltration membrane with a pore size of 0.5 microns;

[0104] The raw materials were vacuum dried, the drying temperature was controlled between 60℃ and 70℃, and the drying time was 3 hours to 5 hours to remove moisture and volatile impurities to ensure that the purity of the raw materials reached the preset standard. After pretreatment of a batch of raw materials, it was found that the content of particulate impurities was reduced from the initial 500ppm to 0.5ppm, and the moisture content was reduced from 0.8% to 0.05%, which effectively improved the purity of the raw materials.

[0105] The process of filtering the raw material using a multi-stage filtering device comprises:

[0106] The first filtration uses a 5-micron pore size filter and calculates the first filtration efficiency E1:

[0107]

[0108] The secondary filtration uses a filter with a pore size of 3 microns, and the secondary filtration efficiency E2 is calculated as follows:

[0109]

[0110] The third filtration is performed using an ultrafiltration membrane with a pore size of 0.5 microns, and the third filtration efficiency E3 is calculated as follows:

[0111]

[0112] Wherein, C0 represents the impurity content of the initial particles of the raw material (unit: ppm);

[0113] C1 represents the particle impurity content after the first filtration (unit: ppm);

[0114] C2 represents the particle impurity content after secondary filtration (unit: ppm);

[0115] C3 represents the particle impurity content after three filtrations (unit: ppm);

[0116] E1 represents the first filtration efficiency;

[0117] E2 represents the filtration efficiency of the secondary filtration relative to the raw material after the first filtration;

[0118] E3 represents the filtration efficiency of the raw material after tertiary filtration relative to that after secondary filtration;

[0119] 1 represents the overall proportion of initial impurity content;

[0120] In this formula, C0 represents the total amount of particulate impurities contained in the raw material before filtering at a specific stage. It is an important indicator to measure the initial purity of the raw material. Its value directly reflects the initial level of impurities in the raw material.

[0121] C1 refers to the amount of particulate impurities remaining in the raw material after a certain level of filtration, which reflects the removal effect of this level of filtration on particulate impurities. The obtained value is the proportion of impurities removed by the filtration at this stage to the initial impurities. In order to convert this proportion into a percentage form so as to more intuitively express the filtration efficiency, multiply it by 100% to convert this proportion into the filtration efficiency E, so as to intuitively evaluate the ability of each stage of filtration process to remove particulate impurities, thereby determining the performance of the entire multi-stage filtration system, so as to timely adjust or optimize the filtration process parameters;

[0122] The first filtration uses a 5-micron pore filter. Assuming that the initial particle impurity content C0 = 1000ppm, the particle impurity content C1 = 500ppm after the first filtration.

[0123] The first filtration efficiency

[0124]

[0125] After the first filtration, 50% of the initial impurities are removed;

[0126] The secondary filtration uses a 3-micron pore size filter. If the particle impurity content C2 after the secondary filtration is 100ppm, the secondary filtration efficiency is relative to the primary filtration.

[0127]

[0128] After the second filtration, 80% of the impurities are removed;

[0129] Finally, a third filtration is performed using an ultrafiltration membrane with a pore size of 0.5 microns. If the final particle impurity content C3 = 10 ppm;

[0130] The filtration efficiency of the third filtration relative to the secondary filtration is

[0131]

[0132] After the third filtration, 90% of the impurities are removed.

[0133] The vacuum drying of the raw materials specifically includes the following methods:

[0134] The drying temperature is controlled between 60℃ and 70℃, and the drying time is 3 hours to 5 hours to remove moisture and volatile impurities to ensure that the purity of the raw materials meets the preset standards;

[0135]

[0136] Wherein, R represents the removal rate;

[0137] M0 represents the initial moisture content of the raw material;

[0138] M1 represents the moisture content after drying;

[0139] It is used to calculate the ratio of the removed part to the initial amount;

[0140] ×100% represents the removal rate converted into percentage form;

[0141] Assume that the initial moisture content of the raw material is M0 = 5%, and the moisture content after vacuum drying is M1 = 0.5%;

[0142] The water removal rate

[0143] During the electrolyte synthesis reaction, the reaction temperature is set according to different reaction stages, and the temperature fluctuation range is controlled within ±2°C; more specifically, the following steps are included:

[0144] During the synthesis reaction of the electrolyte, the reaction temperature is controlled to maintain the temperature in the reactor between 25°C and 35°C. The reaction temperature is monitored in real time by a temperature sensor and linked with the heating device and the cooling device through a feedback control system.

[0145] When the reaction temperature is higher than the set upper limit of 35°C, the cooling device is started to cool it down; when the reaction temperature is lower than the set lower limit of 25°C, the heating device is started to increase the temperature, so that the reaction temperature fluctuation range is controlled within ±2°C, ensuring that the reaction is carried out within the optimal temperature range, so as to improve the reaction conversion rate and product purity;

[0146] When the reaction temperature is controlled at 20°C, the reaction conversion rate is P1=60%; the product purity is Q1=98.5%; when the temperature is controlled at 30°C, the reaction conversion rate is P2=85%, and the product purity is Q2=99.5%.

[0147] The pressure in the reactor is adjusted according to the reaction stages in different periods, and the pressure fluctuation is controlled within ±10kPa; more specifically, the following steps are included:

[0148] As the reaction proceeds, the pressure is gradually adjusted according to the reaction process and material state; in the initial stage of the reaction, the pressure in the reactor is set to 100 kPa, in the middle stage of the reaction, the pressure is adjusted to 150 kPa, and in the late stage of the reaction, the pressure is controlled at 200 kPa;

[0149] The pressure change is monitored in real time by a pressure sensor, and the pressure is maintained stable by a pressure regulating device. The pressure fluctuation is controlled within ±10kPa to promote the reaction equilibrium to move towards the production of high-purity electrolyte. When the pressure fluctuation exceeds ±20kPa, the impurity content in the electrolyte will increase by Z=50ppm. When controlled within ±10kPa, the impurity content can be stably controlled at 10ppm.

[0150] Set different stirring speeds at different stages of the reaction to ensure uniform mixing of materials. The more specific operating steps are as follows:

[0151] The stirring member used for stirring is a paddle-type stirring paddle. In the early stage of the reaction, the stirring speed is set to 90-110 rpm. As the reaction progresses, the stirring speed is increased to 190-210 rpm in the middle stage of the reaction and reduced to 140-160 rpm in the late stage of the reaction.

[0152] The stirring speed is adjusted according to the reaction time by the speed controller to achieve the best mixing uniformity of the materials, avoid the occurrence of side reactions caused by local uneven concentration, and thus improve the purity of the electrolyte. Through experimental observation, when the stirring speed is unreasonable (such as 50 rpm throughout the process), local concentration differences will appear in the reaction system, resulting in the proportion of impurities produced by side reactions reaching A1=10%; while by adopting the stirring speed control of the present invention, the proportion of side reaction impurities can be reduced to A2=2%.

[0153] Ion exchange resin columns are used to remove metal ion impurities, and molecular sieve adsorption devices are used to remove residual moisture and small molecular impurities; more specifically, they include:

[0154] The use of an ion exchange resin column to remove metal ion impurities specifically includes:

[0155] Control the flow rate of the ion exchange resin column between 20 ml / min and 30 ml / min to ensure that the metal ion removal rate reaches more than 99%;

[0156] For example, the electrolyte containing I0=100ppm metal ions is treated with an ion exchange resin column, and the metal ion concentration is reduced to I1=1ppm. The metal ion removal rate is:

[0157]

[0158] In the formula, F represents the removal rate;

[0159] I0 represents the initial amount;

[0160] I1 represents the amount remaining after treatment;

[0161] It indicates the ratio of the removed part to the initial amount;

[0162] ×100% means the removal rate converted into percentage;

[0163] 99% indicates the percentage of the initial material that has been removed.

[0164] The method of removing residual moisture and small molecule impurities by using a molecular sieve adsorption device specifically comprises the following steps:

[0165] Preparation

[0166] First, a molecular sieve with a pore size of 3 to 5 angstroms should be selected, and the selected molecular sieve should be installed in the adsorption device to ensure that the device is well sealed to prevent external impurities from entering and affecting the adsorption effect;

[0167] Molecular sieve is a kind of aluminosilicate crystal with uniform microporous structure, and its pore size is comparable to the size of molecules. It can selectively adsorb molecules according to their size and shape. For the removal of water and small molecule impurities in the production of lithium battery electrolyte, its mechanism of action is as follows:

[0168] When the electrolyte containing water and small molecule impurities comes into contact with the molecular sieve, the water molecules and small molecule impurity molecules can enter the micropores of the molecular sieve. This is because the size of the micropores of the molecular sieve matches the size of these molecules, while the main components in the electrolyte (such as large molecules such as lithium salts and organic solvents) cannot enter the micropores of the molecular sieve due to their large size, thus achieving selective adsorption of water and small molecule impurities.

[0169] Adsorption operation

[0170] The flow rate of the electrolyte through the molecular sieve adsorption device is 20-30 ml / min; in the process of the electrolyte passing through the molecular sieve, water molecules and small molecular impurities are adsorbed by the molecular sieve, and the adsorption time is between 2-4 hours, so that the water content in the electrolyte is less than 20ppm and the small molecular impurity content is less than 5ppm;

[0171] More specifically:

[0172] 1. The electrolyte passes through the molecular sieve adsorption device at a certain flow rate. The flow rate is generally controlled within a certain range, such as between 20 ml / min and 30 ml / min. If the flow rate is too fast, the residence time of the electrolyte in the molecular sieve is too short, which may lead to incomplete adsorption; if the flow rate is too slow, it will affect production efficiency.

[0173] 2. When the electrolyte passes through the molecular sieve, water molecules and small molecular impurities are adsorbed by the molecular sieve. The adsorption time is determined according to the actual situation, generally between 2 hours and 4 hours. During this period, the molecular sieve continuously adsorbs water and small molecular impurities, gradually reducing the impurity content in the electrolyte.

[0174] 3. Before adsorption, the water content in the electrolyte may be as high as 50ppm, and the small molecule impurity content is 20ppm. After molecular sieve adsorption, the water content can be reduced to below 10ppm, and the small molecule impurity content can be reduced to below 5ppm, thereby significantly improving the purity of the electrolyte.

[0175] Post-adsorption treatment

[0176] When the adsorption of the molecular sieve decreases, the molecular sieve needs to be regenerated to desorb the water and small molecular impurities adsorbed in the micropores of the molecular sieve, restore the adsorption performance of the molecular sieve so that it can be used again, and the electrolyte after adsorption treatment should be tested.

[0177] According to the test, after the molecular sieve adsorption, the moisture content decreased from H0=50ppm to H1=10ppm, and the small molecule impurity content decreased from S0=20ppm to S1=3ppm.

[0178] More specifically:

[0179] When the molecular sieve adsorption reaches a certain time or the adsorption effect decreases (for example, it is found through testing that the impurity content in the electrolyte no longer decreases after adsorption), the molecular sieve needs to be regenerated. The regeneration method usually includes heating desorption, etc., so that the water and small molecule impurities adsorbed in the micropores of the molecular sieve are desorbed, and the adsorption performance of the molecular sieve is restored for reuse; at the same time, the electrolyte after adsorption treatment is tested to ensure that its water and small molecule impurity content meets the production requirements of high-purity lithium battery electrolyte. The test items include water content, type and content of small molecule impurities, etc. Commonly used test methods include Karl Fischer water determination, gas chromatography, etc.; the step of removing residual water and small molecule impurities through the molecular sieve adsorption device is of great significance to ensure the high purity and high performance of lithium battery electrolyte.

[0180] Conduct quality inspection on finished products and make feedback adjustments to production process parameters based on the inspection results. More specific inspections include:

[0181] The test items include purity, conductivity, moisture content, and metal ion content. According to the test results, the parameters in the production process are adjusted. If the purity of the finished product does not meet the preset high purity standard, the corresponding parameters are fine-tuned. The adjustment range is determined according to the degree of deviation. If the purity deviation is within 0.1%, the parameter adjustment range is 1% of the original set value; if the purity deviation is within 0.2%, the parameter adjustment range is 2% of the original set value, and so on, forming a closed-loop control. Continuously optimize the production process parameters to ensure the high purity stability of each batch of electrolyte.

[0182] Among them, embodiment 2 is the best embodiment.

[0183] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A parameter control method for producing high-purity lithium battery electrolyte, characterized in that: The following steps are involved: Pre-treating the raw materials, including the treatment of lithium salts, organic solvents and additives; and vacuum drying the raw materials; During the electrolyte synthesis reaction, the reaction temperature is set according to different reaction stages and the temperature is controlled within a preset temperature range; Adjust the pressure in the reactor according to the reaction stages at different time periods and control the pressure within the preset pressure range; set different stirring speeds at different reaction stages to ensure uniform mixing of materials; Ion exchange resin columns are used to remove metal ion impurities, and molecular sieve adsorption devices are used to remove residual moisture and small molecular impurities; Conduct quality inspection on finished products and make feedback adjustments to production process parameters based on the inspection results.

2. The parameter control method for producing high-purity lithium battery electrolyte according to claim 1, characterized in that: The pretreatment method of the raw material is to filter the raw material with a multi-stage filtration device, with the filtration accuracy increasing in sequence, to remove particulate impurities therein, the multi-stage filtration includes primary filtration, secondary filtration and tertiary filtration, wherein the primary filtration uses a filter screen with a pore size of 5 microns, the secondary filtration uses a filter screen with a pore size of 3 microns, and the tertiary filtration uses an ultrafiltration membrane with a pore size of 0.5 microns; The raw materials are vacuum dried with the drying temperature controlled between 60°C and 70°C for 3 to 5 hours to remove moisture and volatile impurities to ensure that the purity of the raw materials meets the preset standards.

3. The parameter control method for producing high-purity lithium battery electrolyte according to claim 2, characterized in that: The process of filtering the raw material using a multi-stage filtering device comprises: The first filtration uses a 5-micron pore size filter and calculates the first filtration efficiency E1: The secondary filtration uses a filter with a pore size of 3 microns, and the secondary filtration efficiency E2 is calculated as follows: The third filtration is performed using an ultrafiltration membrane with a pore size of 0.5 microns, and the third filtration efficiency E3 is calculated as follows: Wherein, C0 represents the impurity content of the initial particles of the raw material (unit: ppm); C1 represents the particle impurity content after the first filtration (unit: ppm); C2 represents the particle impurity content after secondary filtration (unit: ppm); C3 represents the particle impurity content after three filtrations (unit: ppm); E1 represents the first filtration efficiency; E2 represents the filtration efficiency of the secondary filtration relative to the raw material after the first filtration; E3 represents the filtration efficiency of the raw material after tertiary filtration relative to that after secondary filtration.

4. The parameter control method for producing high-purity lithium battery electrolyte according to claim 3, characterized in that: The vacuum drying process of the raw materials specifically includes the following methods: Control the drying temperature between 60℃ and 70℃, the drying time between 3 hours and 5 hours, and calculate the drying rate of the raw materials: Where R represents the drying rate; M0 represents the initial moisture content of the raw material; M1 represents the moisture content after drying. Assume that the initial moisture content of the raw material is M0 = 5%, and the moisture content after vacuum drying is M1 = 0.5%; Drying rate 5. The parameter control method for producing high-purity lithium battery electrolyte according to claim 1, characterized in that: The precise setting of the reaction temperature according to different reaction stages specifically includes: During the synthesis reaction of the electrolyte, the reaction temperature is controlled to maintain the temperature in the reactor between 25°C and 35°C. The reaction temperature is monitored in real time by a temperature sensor and linked with the heating device and the cooling device through a feedback control system. When the reaction temperature is higher than the set upper limit of 35°C, the cooling device is started to cool it down; when the reaction temperature is lower than the set lower limit of 25°C, the heating device is started to heat it up; When the reaction temperature is controlled at 20°C, the reaction conversion rate is P1=60%; the product purity is Q1=98.5%; when the temperature is controlled at 30°C, the reaction conversion rate is P2=85%, and the product purity is Q2=99.5%.

6. The parameter control method for producing high-purity lithium battery electrolyte according to claim 1, characterized in that: Adjusting the pressure in the reactor according to the reaction stages at different times specifically includes: The pressure was gradually adjusted according to the reaction process and material status; in the initial stage of the reaction, the pressure in the reactor was set to 100 kPa, in the middle stage of the reaction, the pressure was adjusted to 150 kPa, and in the late stage of the reaction, the pressure was controlled at 200 kPa; The pressure change is monitored in real time by a pressure sensor, and the pressure is maintained stable by a pressure regulating device. The pressure fluctuation is controlled within ±10kPa to promote the reaction equilibrium to move towards the production of high-purity electrolyte. When the pressure fluctuation exceeds ±20kPa, the impurity content in the electrolyte will increase by Z=50ppm. When controlled within ±10kPa, the impurity content can be stably controlled at 10ppm.

7. The parameter control method for producing high-purity lithium battery electrolyte according to claim 1, characterized in that: Different stirring speeds are set at different stages of the reaction, and the specific setting method is as follows: The stirring member used for stirring is a paddle-type stirring paddle. In the early stage of the reaction, the stirring speed is set to 90-110 rpm. As the reaction progresses, the stirring speed is increased to 190-210 rpm in the middle stage of the reaction and reduced to 140-160 rpm in the late stage of the reaction.

8. The parameter control method for producing high-purity lithium battery electrolyte according to claim 1, characterized in that: The use of an ion exchange resin column to remove metal ion impurities specifically includes: Control the flow rate of the ion exchange resin column between 20 ml / min and 30 ml / min, and calculate the metal ion removal rate: In the formula, F represents the metal ion removal rate; I0 represents the initial amount of metal ions; I1 represents the amount of metal ions remaining after treatment.

9. The parameter control method for producing high-purity lithium battery electrolyte according to claim 1, characterized in that: The method of removing residual moisture and small molecule impurities by using a molecular sieve adsorption device specifically comprises the following steps: Preparation First, a molecular sieve with a pore size of 3 to 5 angstroms is selected and the selected molecular sieve is installed in an adsorption device; Adsorption operation The electrolyte flows through the molecular sieve adsorption device at a flow rate of 20-30 ml / min to adsorb water molecules and small molecular impurities for a period of 2-4 hours, so that the water content in the electrolyte is less than 20 ppm and the small molecular impurity content is less than 5 ppm; Post-adsorption treatment When the adsorption of the molecular sieve decreases, the molecular sieve is regenerated to desorb the water and small molecular impurities adsorbed in the micropores of the molecular sieve, and the electrolyte after the adsorption treatment is tested.

10. The parameter control method for producing high-purity lithium battery electrolyte according to claim 1, characterized in that: Comprehensive quality testing of finished lithium battery electrolyte products includes: The testing items include purity, conductivity, moisture content, and metal ion content indicators. Based on the test results, feedback adjustments are made to the parameters in the production process. If the purity of the finished product does not meet the preset high purity standard, the corresponding parameters are fine-tuned with an adjustment range of 10 times the purity deviation.

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