Phosphate ester product, electrolyte and battery

Abstract

The invention belongs to the technical field of batteries, and provides a phosphate product, an electrolyte and a battery, the phosphate product comprises a silicon-based fluorophosphate compound and a siloxane compound, and the siloxane compound is obtained by hydrolyzing the silicon-based fluorophosphate compound; based on the mass of the silicon-based fluorophosphate compound, the content m of the siloxane compound is more than 0 and less than or equal to 1.0%; the silicon-based fluorophosphate compound is shown as a formula 1, the siloxane compound is shown as a formula 2; the formula 2 is shown in the specification; wherein R1, R2, R3, R '1, R' 2 and R '3 are respectively and independently selected from any one of H, F, C1-C4 alkyl groups, C1-C4 fluoroalkyl groups, C2-C4 alkenyl groups, C2-C4 fluoroalkenyl groups, C2-C4 alkynyl groups, C2-C4 fluoroalkynyl groups, C5-C7 cycloalkyl groups, R4 substituted phenyl groups and R5 substituted benzyl groups. The silicon-based fluorophosphate product is applied to batteries and shows good low-temperature performance and high-temperature performance.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and more specifically, relates to phosphate ester products, electrolytes, and batteries. Background Technology

[0002] With the rapid development of markets such as electronic devices, electric vehicles, smart homes, power tools, and intelligent transportation, the demand for batteries is constantly increasing. Lithium-ion batteries, for example, are widely used in consumer electronics, energy storage and power batteries, and smart homes due to their advantages such as high specific energy, long cycle life, and low self-discharge. Typically, a battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The electrolyte usually includes a solvent, a lithium salt electrolyte, and electrolyte additives. Adding electrolyte additives can improve battery performance. Choosing appropriate additives has a significant impact on the battery's electrochemical performance. Summary of the Invention

[0003] The technical solution of this application was developed by the inventor based on the following discoveries: Silicon-based fluorophosphate compounds can be used as additives in electrolytes, which can effectively improve the overall electrochemical performance of batteries.

[0004] However, during the research process, it was found that using this silicon-based fluorophosphate compound as an electrolyte additive did not have an ideal effect on improving the high-temperature and low-temperature performance of the battery. This is mainly because the silicon-based fluorophosphate compound, when used as an electrolyte additive, sometimes causes abnormal changes in electrolyte acidity and uneven thickness of the constructed interfacial film, making it difficult for the battery to maintain stable capacity performance under low-temperature conditions. Under high-temperature conditions, the battery is prone to abnormal gas generation, leading to a sudden drop in capacity after a certain number of cycles and storage periods (a sudden drop in capacity typically refers to a sharp decrease in the capacity of a lithium-ion battery during cycling), resulting in a sudden and abnormal decline in the overall battery performance.

[0005] Upon review, the inventors discovered that even after configuring the silicon-based fluorophosphate compound shown in Formula 1 into a basic electrolyte formulation and ensuring that the electrolyte meets industry standards (testing the electrolyte according to the HG_T 4067-2015 standard) and applying it to the battery for performance testing, the battery test results still showed the aforementioned problems.

[0006] Meanwhile, during the preparation and storage of the compounds, it was found that these compounds produced white fumes upon contact with air. Analysis of the white fumes revealed that they were mainly composed of hydrogen fluoride, a complete decomposition product of these compounds. Combined with analysis of the compound's structural stability and decomposition mechanism, it was determined that the potential decomposition products of these compounds may contain siloxanes. Analysis of the effects of these siloxane compounds confirmed that they are the culprits causing the silicon-based fluorophosphate compounds to fail to achieve their full effect, as well as the abnormal gas production and rapid battery depletion under high-temperature conditions. Further gradient verification experiments were conducted by adding different amounts of water to the strictly water-controlled silicon-based fluorophosphate compounds. It was found that these compounds are sensitive to water and will hydrolyze if storage conditions are not carefully observed. Upon contact with water, they decompose to produce silanols. Under acidic conditions, silanol structures readily dimerize to form siloxane compounds, as shown in Formula 2.

[0007] Formula 2; R'1, R'2, and R'3 are each independently selected from any one of H, F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 fluoroalkenyl, C2-C4 alkynyl, C2-C4 fluoroalkynyl, C5-C7 cycloalkyl, R4-substituted phenyl, and R5-substituted benzyl.

[0008] This siloxane compound exhibits certain thermal stability in the electrolyte and demonstrates an effect of suppressing high-temperature gas generation in silicon-based battery systems. However, when used in systems containing silicon-based fluorophosphate compounds, it affects the stability of the electrode / electrolyte interface film constructed with silicon-based fluorophosphate compounds, resulting in a rougher interface film. This negatively impacts the smoothness of the SEI film and its interfacial impedance. Furthermore, the siloxane compound undergoes side reactions to produce silicon-based fluorides, leading to high-temperature gas generation and performance degradation in the battery. As a decomposition byproduct of silicon-based fluorophosphate compounds, the increased amount of siloxane compounds in the sample indicates increased consumption of these compounds, resulting in a lower actual effective content than the added amount. This leads to the inability to stably construct the CEI and SEI films, negatively affecting the stable and continuous improvement of battery storage and cycle performance. More importantly, the residual siloxane compounds affect battery impedance and gas generation, negatively impacting the battery's high and low temperature performance.

[0009] Based on this, this application controls the content of siloxane compounds in the silicon-based fluorophosphate compound to ≤1.0%, so as to avoid the silicon-based fluorophosphate compound from failing to exert its actual improvement effect on the battery due to siloxane compounds.

[0010] Therefore, the first aspect of this application provides a silicon-based fluorophosphate product. According to embodiments of this application, the silicon-based fluorophosphate product comprises: a silicon-based fluorophosphate compound and a siloxane compound; based on the mass of the silicon-based fluorophosphate compound, the content m of the siloxane compound satisfies: 0 < m ≤ 1.0%; the silicon-based fluorophosphate compound is shown in Formula 1:

[0011] Formula 1; Siloxane compounds are shown in Formula 2:

[0012] Formula 2; R1, R2, R3, R'1, R'2 and R'3 are each independently selected from any one of H, F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 fluoroalkenyl, C2-C4 alkynyl, C2-C4 fluoroalkynyl, C5-C7 cycloalkyl, R4-substituted phenyl and R5-substituted benzyl.

[0013] The silicon-based fluorophosphate compound in this application can be used as an additive in the electrolyte, which has a good effect on improving the overall electrochemical performance of the battery. Specifically, it is manifested in the formation of stable CEI film (Cathode Electrolyte Interphase) and SEI film (Solid Electrolyte Interphase) on the positive electrode surface and the negative electrode surface, respectively. This avoids interfacial side reactions between the electrode material and the electrolyte, and provides stable protection for the positive electrode material, negative electrode material and electrolyte. At the same time, it helps to optimize the transport of lithium ions in the interfacial film, reduce interfacial impedance, and improve the cycle stability and low-temperature capacity of the battery. Specifically, the silicon-based fluorophosphate compound and the electrolyte solvent have similar energy level orbitals. During charge and discharge, they react synchronously with the electrolyte solvent to jointly construct a dense and stable interfacial film. The Si-O bonds in this silicon-based fluorophosphate compound have high reactivity and can undergo electrochemical reactions during charge and discharge to produce difluorophosphate and silicon-containing compounds. Both can further undergo electrochemical reactions to participate in the construction of the electrode-electrolyte interfacial film. The difluorophosphate ions will react with lithium ions to deposit lithium difluorophosphate salt, which will gradually decompose to produce lithium fluoride, lithium phosphate, and Li. x PO y F zLithium salts that improve lithium-ion transport; and silicon-based groups in silicon-containing compounds undergo electrochemical polymerization to form dense polysiloxanes. The introduction of the aforementioned inorganic lithium salts and organic polysiloxanes endows the positive electrode CEI film and negative electrode SEI film with advantages such as high conductivity, rigidity, and flexibility. Among them, the P=O in lithium phosphate salts and the Si-O in polysiloxanes play a good stabilizing role for positive electrode metal ions, reducing the oxidative activity of metal ions on the solvent, and inhibiting the dissolution of metal ions in the positive electrode active material, thereby alleviating the capacity decay of the battery under high temperature conditions or long-term cycling, and improving high temperature stability and cycle stability. For the negative electrode, silicon-containing compounds can form a polymer attached to the negative electrode surface as a framework structure, maintaining the stability of the interface film. Fluorinated lithium phosphate can promote the interfacial transport of lithium ions and reduce the impedance of the SEI interface film itself. The P=O in it can also capture impurity ions in the electrolyte (impurity metal ions introduced by lithium salts and transition metal ions dissolved from the positive electrode material), which not only alleviates the catalytic decomposition of solvent molecules by dissolved transition metal ions, but also prevents the increase in impedance caused by the reduction and deposition of impurity ions.

[0014] When R1, R2, and R3 are all selected from short-chain alkyl groups, the steric hindrance of the molecules is small, and the resulting silicon-containing compounds are easy to polymerize, resulting in a thinner and more stable interfacial film, and a more balanced high and low temperature performance of the battery. As the alkyl chain length increases or larger structural groups are included (such as phenyl, substituted phenyl, etc.), the interference of impurities and byproducts in the electrolyte on the interfacial film may be avoided, thus improving high-temperature performance. When the substituent groups contain unsaturated structures (such as carbon-carbon double bonds, carbon-carbon triple bonds, etc.), the silicon-containing compounds can not only construct Si-O-containing polysiloxanes, but the unsaturated structures can also polymerize, further improving the high-temperature stability of the interfacial film. When R1, R2, and R3 contain fluorine-substituted structures, the fluorine-containing components can reduce interfacial impedance and improve the low-temperature performance of the battery.

[0015] Based on the water-sensitive nature of the silicon-based fluorophosphate compounds shown in Formula 1, if moisture and environmental conditions are not specially controlled during product storage or handling, moisture intrusion can lead to product decomposition and the generation of siloxane compound impurities under certain conditions. These siloxane compound impurities are shown in Formula 2.

[0016] Formula 2; R'1, R'2, and R'3 are each independently selected from any one of H, F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 fluoroalkenyl, C2-C4 alkynyl, C2-C4 fluoroalkynyl, C5-C7 cycloalkyl, R4-substituted phenyl, and R5-substituted benzyl. This siloxane compound affects the stability of the electrode / electrolyte interface film constructed from silicon-based fluorophosphate compounds, resulting in a rougher interface film and negatively impacting the smoothness and interfacial impedance of the SEI film. Furthermore, the siloxane compound undergoes side reactions to produce silicon-based fluorides, leading to high-temperature gas generation and performance degradation in the battery. Strictly controlling the content of siloxane impurities in this silicon-based fluorophosphate compound is key to solving these problems. Controlling the content of siloxane impurities in this compound to below 1.0% can improve the performance degradation of silicon-based fluorophosphate compounds in electrolytes caused by impurities and / or hydrolysis byproducts.

[0017] In some embodiments of this application, based on the mass of the siloxane fluorophosphate compound, the content m of the siloxane compound impurities satisfies: 1 ppm ≤ m ≤ 1.0%.

[0018] In some embodiments of this application, R4 and R5 are each independently selected from any one of C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, C1-C4 fluoroalkyl, C2-C4 fluoroalkenyl, and C2-C4 fluoroalkynyl.

[0019] In some embodiments of this application, R1, R2, and R3 are each independently any one of C1-C2 alkyl and C2-C3 alkenyl; and / or, R4 and R5 are each independently fluorine or methyl.

[0020] In some embodiments of this application, the silicon-based fluorophosphate compound includes at least one of the following compounds: The compound shown in Formula 1-1 Compounds shown in Formula 1-2 Compounds shown in Formulas 1-3 Compounds shown in Formulas 1-4 Compounds shown in Formulas 1-5 Compounds shown in Formulas 1-6 Compounds shown in Formulas 1-7 Compounds shown in Formulas 1-8 Compounds shown in Formulas 1-9 Compounds shown in Formula 1-10 Compounds shown in Formula 1-11 Compounds shown in Formula 1-12 Compounds shown in Formula 1-13 Compounds shown in Formula 1-14 Compounds shown in Formula 1-15 Compounds shown in Formula 1-16 Compounds shown in Formula 1-17 The compounds shown in Formula 1-18 The compounds shown in Formula 1-19 The compounds shown in Formula 1-20 The compounds shown in Formula 1-21 The compounds shown in Formula 1-22 .

[0021] In some embodiments of this application, R'1 is the same as R1, R'2 is the same as R2, and R'3 is the same as R3.

[0022] In some embodiments of this application, the siloxane compound includes at least one of the following compounds: The compound shown in Formula 2-1 The compound shown in Formula 2-2 Compounds shown in Formula 2-3 Compounds shown in Formula 2-4 Compounds shown in Formula 2-5 Compounds shown in Formula 2-6 Compounds shown in Formula 2-7 Compounds shown in Formula 2-8 Compounds shown in Formula 2-9 Compounds shown in Formula 2-10 The compound shown in Formula 2-11 Compounds shown in Formula 2-12 Compounds shown in Formula 2-13 The compound shown in Formula 2-14 Compounds shown in Formula 2-15 Compounds shown in Formula 2-16 Compounds shown in Formula 2-17 Compounds shown in Formula 2-18 The compound shown in Formula 2-19 Compounds shown in Formula 2-20 Compounds shown in Formula 2-21 Compounds shown in Formula 2-22 .

[0023] In some embodiments of this application, the moisture content of the product in the storage or operating environment is ≤0.15 mg / cm³. 3Under the conditions of not exceeding 100 days, based on the mass of the silicon-based fluorophosphate compound, the content of siloxane compounds m≤0.95%.

[0024] In some embodiments of this application, the moisture content of the product in the storage or operating environment is ≤0.12 mg / cm³. 3 Under the conditions of not exceeding 100 days, based on the mass of the silicon-based fluorophosphate compound, the content of siloxane compounds m ≤ 0.90%.

[0025] In some embodiments of this application, the product is stored at a temperature not exceeding 25 °C for no more than 100 days, and the content of siloxane compounds is ≤0.85% based on the mass of the silicon-based fluorophosphate compound.

[0026] In some embodiments of this application, the product is stored at a temperature not higher than 0 °C for no more than 100 days, and the content of siloxane compounds m is ≤0.80% based on the mass of the silicon-based fluorophosphate compound.

[0027] In some embodiments of this application, the product is operated or stored for no more than 50 days at a temperature not exceeding 25°C, and the content of the siloxane compound m is ≤0.7% based on the mass of the silicon-based fluorophosphate compound.

[0028] In some embodiments of this application, the product is operated or stored for no more than 30 days at a temperature not exceeding 25°C, and the content of the siloxane compound m is ≤0.5% based on the mass of the siloxane compound.

[0029] The second aspect of this application proposes the application of phosphate ester products in the fields of electrolytes and batteries.

[0030] A third aspect of this application discloses an electrolyte comprising the aforementioned phosphate ester product.

[0031] The electrolyte provided in this application contains the aforementioned phosphate ester product, which is beneficial for improving the performance of the battery by enhancing the silicon-based fluorophosphate ester compound shown in Formula 1.

[0032] In some embodiments of this application, the mass percentage of the phosphate ester product is 0.05% to 5.0% based on the total mass of the electrolyte.

[0033] A fourth aspect of this application provides a battery including the electrolyte described above.

[0034] The battery provided in this embodiment exhibits good low-temperature discharge performance, high-temperature cycling performance, and high-temperature storage stability.

[0035] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 The image shows the GC test results for compounds 1-2. The peak with a retention time of 3.158 min is the impurity siloxane compound, and the peak with a retention time of 3.622 min is the compound 1-2.

[0037] Figure 2 Showing Figure 1 The GC-MS chromatogram of the peak at retention time 3.158 shows a perfect fit between the m / z=147 in the upper plot and the fitting result of siloxane compounds, confirming that the compound corresponding to this peak is a siloxane compound.

[0038] Figure 3 Showing Figure 1 The GC-MS chromatogram of the peak at retention time 3.622 shows a perfect fit between the m / z=159 in the upper plot and the fitting result of compound 1-2, confirming that the peak corresponds to compound 1-2. Detailed Implementation

[0039] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0040] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0041] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0042] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0043] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0044] Silicon-based fluorophosphate compounds can be used as additives in electrolytes, which can effectively improve the overall electrochemical performance of batteries.

[0045] However, during the research process, it was found that using this silicon-based fluorophosphate compound as an electrolyte additive did not have an ideal effect on improving the high-temperature and low-temperature performance of the battery. This is mainly because the silicon-based fluorophosphate compound, when used as an electrolyte additive, sometimes causes abnormal changes in electrolyte acidity and uneven thickness of the constructed interfacial film, making it difficult for the battery to maintain stable capacity performance under low-temperature conditions. Under high-temperature conditions, the battery is prone to abnormal gas generation, leading to a sudden drop in capacity after a certain number of cycles and storage periods (a sudden drop in capacity typically refers to a sharp decrease in the capacity of a lithium-ion battery during cycling), resulting in a sudden and abnormal decline in the overall battery performance.

[0046] Upon review, the inventors discovered that even after configuring the silicon-based fluorophosphate compound shown in Formula 1 into a basic electrolyte formulation and ensuring that the electrolyte meets industry standards (testing the electrolyte according to the HG_T 4067-2015 standard) and applying it to the battery for performance testing, the battery test results still showed the aforementioned problems.

[0047] Meanwhile, during the preparation and storage of the compounds, it was found that these compounds produce white fumes upon contact with air. Analysis of the white fumes revealed that they are mainly composed of hydrogen fluoride, a complete decomposition product of these compounds. Combined with analysis of the compound's structural stability and decomposition mechanism, it was determined that the potential decomposition products of these compounds may contain siloxanes. Analysis of the effects of these siloxane compounds confirmed that they are the culprits causing the silicon-based fluorophosphate compounds to fail to exert their full effect, as well as the abnormal gas production and rapid battery depletion under high-temperature conditions. Further gradient verification experiments were conducted by adding different amounts of water to the strictly water-controlled silicon-based fluorophosphate compounds. It was found that these compounds are sensitive to water and easily hydrolyze. Upon contact with water, they decompose to produce silanols. Under acidic conditions, the silanol structure easily dimers to form siloxane compounds, as shown in Formula 2.

[0048] Formula 2; R'1, R'2, and R'3 are each independently selected from any one of H, F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 fluoroalkenyl, C2-C4 alkynyl, C2-C4 fluoroalkynyl, C5-C7 cycloalkyl, R4-substituted phenyl, and R5-substituted benzyl.

[0049] This siloxane compound exhibits certain thermal stability in the electrolyte and demonstrates an effect of suppressing high-temperature gas generation in silicon-based battery systems. However, when used in systems containing silicon-based fluorophosphate compounds, it affects the stability of the electrode / electrolyte interface film constructed with silicon-based fluorophosphate compounds, resulting in a rougher interface film. This negatively impacts the smoothness of the SEI film and its interfacial impedance. Furthermore, the siloxane compound undergoes side reactions to produce silicon-based fluorides, leading to high-temperature gas generation and performance degradation in the battery. As a decomposition byproduct of silicon-based fluorophosphate compounds, the increased amount of residual siloxane compounds during sample production or storage indicates increased consumption of silicon-based fluorophosphate compounds. This results in the actual effective content being less than the added amount, making it impossible to stably construct the CEI and SEI films. This negatively impacts the stable and continuous improvement of battery storage and cycle performance. More importantly, the residual siloxane compounds affect battery impedance and gas generation, negatively impacting the battery's high and low temperature performance.

[0050] Based on this, this application controls the content of siloxane compounds in the silicon-based fluorophosphate compound to ≤1.0%, so as to avoid the silicon-based fluorophosphate compound from failing to exert its actual improvement effect on the battery due to siloxane compounds.

[0051] Therefore, the first aspect of this application provides a phosphate ester product, comprising: a silicon-based fluorophosphate compound and a siloxane compound; based on the mass of the silicon-based fluorophosphate compound, the content m of the siloxane compound satisfies: 0 < m ≤ 1.0%; the silicon-based fluorophosphate compound is shown in Formula 1:

[0052] Formula 1; Siloxane compounds are shown in Formula 2:

[0053] Formula 2; R1, R2, R3, R'1, R'2 and R'3 are each independently selected from any one of H, F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 fluoroalkenyl, C2-C4 alkynyl, C2-C4 fluoroalkynyl, C5-C7 cycloalkyl, R4-substituted phenyl and R5-substituted benzyl.

[0054] The silicon-based fluorophosphate compound in this application can be used as an additive in the electrolyte, which has a good effect on improving the overall electrochemical performance of the battery. Specifically, it is manifested in the formation of stable CEI film (Cathode Electrolyte Interphase) and SEI film (Solid Electrolyte Interphase) on the positive electrode surface and the negative electrode surface, respectively. This avoids interfacial side reactions between the electrode material and the electrolyte, and provides stable protection for the positive electrode material, negative electrode material and electrolyte. At the same time, it helps to optimize the transport of lithium ions in the interfacial film, reduce interfacial impedance, and improve the cycle stability and low-temperature capacity of the battery. Specifically, the silicon-based fluorophosphate compound and the electrolyte solvent have similar energy level orbitals. During charge and discharge, they react synchronously with the electrolyte solvent to jointly construct a dense and stable interfacial film. The Si-O bonds in this silicon-based fluorophosphate compound have high reactivity and can undergo electrochemical reactions during charge and discharge to produce difluorophosphate and silicon-containing compounds. Both can further undergo electrochemical reactions to participate in the construction of the electrode-electrolyte interfacial film. The difluorophosphate ions will react with lithium ions to deposit lithium difluorophosphate salt, which will gradually decompose to produce lithium fluoride, lithium phosphate, and Li. x PO y F z Lithium salts that improve lithium-ion transport; and silicon-based groups in silicon-containing compounds undergo electrochemical polymerization to form dense polysiloxanes. The introduction of the aforementioned inorganic lithium salts and organic polysiloxanes endows the positive electrode CEI film and negative electrode SEI film with advantages such as high conductivity, rigidity, and flexibility. Among them, the P=O in lithium phosphate salts and the Si-O in polysiloxanes play a good stabilizing role for positive electrode metal ions, reducing the oxidative activity of metal ions on the solvent, and inhibiting the dissolution of metal ions in the positive electrode active material, thereby alleviating the capacity decay of the battery under high temperature conditions or long-term cycling, and improving high temperature stability and cycle stability. For the negative electrode, silicon-containing compounds can form a polymer attached to the negative electrode surface as a framework structure, maintaining the stability of the interface film. Fluorinated lithium phosphate can promote the interfacial transport of lithium ions and reduce the impedance of the SEI interface film itself. The P=O in it can also capture impurity ions in the electrolyte (impurity metal ions introduced by lithium salts and transition metal ions dissolved from the positive electrode material), which not only alleviates the catalytic decomposition of solvent molecules by dissolved transition metal ions, but also prevents the increase in impedance caused by the reduction and deposition of impurity ions.

[0055] When R1, R2, and R3 are all selected from short-chain alkyl groups, the steric hindrance of the molecules is small, and the resulting silicon-containing compounds are easy to polymerize, resulting in a thinner and more stable interfacial film, and a more balanced high and low temperature performance of the battery. As the alkyl chain length increases or larger structural groups are included (such as phenyl, substituted phenyl, etc.), the interference of impurities and byproducts in the electrolyte on the interfacial film may be avoided, thus improving high-temperature performance. When the substituent groups contain unsaturated structures (such as carbon-carbon double bonds, carbon-carbon triple bonds, etc.), the silicon-containing compounds can not only construct Si-O-containing polysiloxanes, but the unsaturated structures can also polymerize, further improving the high-temperature stability of the interfacial film. When R1, R2, and R3 contain fluorine-substituted structures, the fluorine-containing components can reduce interfacial impedance and improve the low-temperature performance of the battery.

[0056] Due to the easily hydrolyzed nature of the silicon-based fluorophosphate compound shown in Formula 1, moisture intrusion during product handling or storage can lead to product decomposition and the generation of siloxane compound impurities. These siloxane compound impurities are shown in Formula 2.

[0057] Formula 2; R'1, R'2, and R'3 are each independently selected from any one of H, F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 fluoroalkenyl, C2-C4 alkynyl, C2-C4 fluoroalkynyl, C5-C7 cycloalkyl, R4-substituted phenyl, and R5-substituted benzyl. This siloxane compound affects the stability of the electrode / electrolyte interface film constructed from silicon-based fluorophosphate compounds, resulting in a rougher interface film and negatively impacting the smoothness and interfacial impedance of the SEI film. Furthermore, the siloxane compound undergoes side reactions to produce silicon-based fluorides, leading to high-temperature gas generation and performance degradation in the battery. Strictly controlling the content of siloxane impurities in this silicon-based fluorophosphate compound is key to solving these problems. Controlling the content of siloxane impurities in this compound to below 1.0% can improve the performance degradation of silicon-based fluorophosphate compounds in electrolytes caused by impurities and / or hydrolysis byproducts.

[0058] In specific examples, based on the mass of the siloxane ester compound, the content m of the siloxane compound is 1.0%, 0.95%, 0.90%, 0.85%, 0.80%, 0.75%, 0.70%, 0.65%, 0.60%, 0.55%, 0.50%, 0.45%, 0.40%, 0.35%, 0.30%, 0.25%, 0.20%, 0.15%, 0.10%, etc., or any other value between 1.0% and 0 (excluding 0), including decimals.

[0059] In the specific example, R1, R2, and R3 are each independently selected from any one of H, F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 fluoroalkenyl, C2-C4 alkynyl, C2-C4 fluoroalkynyl, R4-substituted phenyl, and R5-substituted benzyl. The C1-C4 alkyl groups include one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; the C1-C4 fluoroalkyl groups can be partially fluorinated or completely fluorinated. The alkenyl groups of C2-C4 include one of vinyl, propenyl (CH2=CHCH2-), 1-propenyl (CH3CH=CH-), 2-propenyl (CH2=C(CH3)-), butenyl (CH2=CHCH2CH2-), isobutenyl (CH2=CHCH(CH3)-), 1-methylpropenyl (CH2=C(CH3)2-), and 2-methylpropenyl (CH2=CHC(CH3)2-); the fluorinated alkenyl groups of C2-C4 can be partially fluorinated alkenyl groups or completely fluorinated alkenyl groups. Among them, the C2-C4 alkynyl group includes one of ethynyl, 1-propynyl (CH3C≡C-), 2-propynyl (HC≡CCH2-), 1-butynyl (CH3CH2C≡C-), 2-butynyl (CH3C≡CCH2-), 3-butynyl (CH≡CCH2CH2-), and 2-methyl-1-propynyl (HC≡CC(CH3)2); the C2-C4 fluoroalkynyl group can be a partially fluorinated C2-C4 alkynyl group or a completely fluorinated C2-C4 alkynyl group.

[0060] In some embodiments of this application, based on the mass of the siloxane compound, the content m of the siloxane compound satisfies: 1 ppm ≤ m ≤ 1.0%.

[0061] In the embodiments of this application, controlling the content of siloxane compounds in the silicon-based fluorophosphate compound to meet the above conditions can improve the problem of the weakened application performance of the silicon-based fluorophosphate compound in the electrolyte caused by the introduction of impurities and / or hydrolysis byproducts.

[0062] The content m of siloxane compounds can be any value between 1 ppm and 1.0%. In specific examples, the content m of siloxane compounds is 1 ppm, 100 ppm, 500 ppm, 1000 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, 5500 ppm, 6000 ppm, 6500 ppm, 7000 ppm, 7500 ppm, 8000 ppm, 8200 ppm, 8400 ppm, 8500 ppm, 8600 ppm, 8800 ppm, 9000 ppm, 9100 ppm, 9200 ppm, 9300 ppm, 9400 ppm, 9500 ppm, 9600 ppm, 9700 ppm, 9800 ppm, 9900 ppm, 10000 ppm (i.e., 1.0%), etc.

[0063] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.95%.

[0064] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.90%.

[0065] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.85%.

[0066] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.80%.

[0067] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.75%.

[0068] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.70%.

[0069] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.65%.

[0070] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.60%.

[0071] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.65%.

[0072] Furthermore, the content m of siloxane compounds satisfies: 1 ppm ≤ m ≤ 0.50%.

[0073] In some embodiments of this application, R4 and R5 are each independently selected from any one of C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, C1-C4 fluoroalkyl, C2-C4 fluoroalkenyl, and C2-C4 fluoroalkynyl.

[0074] The C1-C4 alkyl groups include one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl. The C1-C4 fluoroalkyl groups can be partially fluorinated or completely fluorinated. The C2-C4 alkenyl groups include one of vinyl, propenyl (CH2=CHCH2-), 1-propenyl (CH3CH=CH-), 2-propenyl (CH2=C(CH3)-), butenyl (CH2=CHCH2CH2-), isobutenyl (CH2=CHCH(CH3)-), 1-methylpropenyl (CH2=C(CH3)2-), and 2-methylpropenyl (CH2=CHC(CH3)2-). The C2-C4 fluoroalkenyl groups can be partially fluorinated or completely fluorinated. Among them, the C2-C4 alkynyl group includes one of ethynyl, 1-propynyl (CH3C≡C-), 2-propynyl (HC≡CCH2-), 1-butynyl (CH3CH2C≡C-), 2-butynyl (CH3C≡CCH2-), 3-butynyl (CH≡CCH2CH2-), and 2-methyl-1-propynyl (HC≡CC(CH3)2); the C2-C4 fluoroalkynyl group can be a partially fluorinated C2-C4 alkynyl group or a completely fluorinated C2-C4 alkynyl group.

[0075] In some embodiments of this application, R1, R2, and R3 are each independently any one of C1-C2 alkyl and C2-C3 alkenyl; and / or, R4 and R5 are each independently fluorine or methyl.

[0076] In the embodiments of this application, R1, R2, and R3 are each independently any one of C1-C2 alkyl groups and C2-C3 alkenyl groups. These groups have shorter carbon chains, which is beneficial for polymerization to form polysiloxanes, while avoiding an increase in the thickness of the interfacial film and thus an increase in impedance.

[0077] In the embodiments of this application, R4 and R5 are each independently fluorine or methyl, and the carbon chains of the substituents are relatively short, which is beneficial for further polymerization and avoids increasing the thickness of the interfacial film.

[0078] In some embodiments of this application, the silicon-based fluorophosphate compound includes at least one of the following compounds: The compound shown in Formula 1-1 (CAS No.: 2708941-25-5) The compound shown in Formula 1-2 (CAS No.: 4414-25-9) Compounds shown in Formulas 1-3 (CAS No.: 13683-39-1) Compounds shown in Formulas 1-4 (CAS No.: 4414-27-1) Compounds shown in Formulas 1-5 (CAS No.: 4414-26-0) Compounds shown in Formulas 1-6 (CAS No.: 4480-02-8) Compounds shown in Formulas 1-7 (CAS No.: 2577172-95-1) Compounds shown in Formulas 1-8 (CAS No.: 13683-40-4) Compounds shown in Formulas 1-9 (CAS No.: 2577172-93-9) Compounds shown in Formula 1-10 (CAS No.: 2708941-27-7) The compound shown in Formula 1-11 (CAS No.: 2287283-36-5) Compounds shown in Formula 1-12 (CAS No.: 6231-57-8) The compound shown in Formula 1-13 (CAS No.: 1386-54-9) The compound shown in Formula 1-14 (CAS No.: 2708941-26-6) The compound shown in Formula 1-15 (CAS No.: 6231-58-9) The compound shown in Formula 1-16 (CAS No.: 6231-59-0) The compound shown in Formula 1-17 (CAS No.: 2577172-94-0) The compound shown in Formula 1-18 (CAS No.: 1871-21-2 of the raw material trivinylchlorosilane) The compound shown in Formula 1-19 (CAS No.: 2069196-19-4 of the raw material dimethylyntyne butylchlorosilane) The compound shown in Formula 1-20 (the CAS number of the raw material dimethyl(trifluoropropenyl)chlorosilane is: 89705-02-2) The compound shown in Formula 1-21 (CAS No.: 1620665-21-5 of the raw material tris(pentafluoroethyl)chlorosilane) The compound shown in Formula 1-22 (CAS No.: 1833-28-9 of the raw material dimethyl(p-methylbenzyl)chlorosilane) .

[0079] The preparation methods of the silicon-based fluorophosphate compounds shown in Formulas 1-18 to 1-22 are as follows: (1) Under a nitrogen atmosphere, chlorosilane compounds are reacted with sodium difluorophosphate at a temperature of 0-40℃ for 0.25-10h to obtain a mixture containing silicon-based fluorophosphate compounds; the molar ratio of chlorosilane compounds to sodium difluorophosphate is greater than or equal to 2:1; (2) Filter the mixture to obtain the filtrate; (3) The filtrate was subjected to vacuum distillation at 30-70℃ and a vacuum of -0.09Mpa to -0.01Mpa to obtain silicon-based fluorophosphate compounds.

[0080] At least one of the silicon-based fluorophosphate compounds shown in Formulas 1-1 to 1-22 provided in this application embodiment can be used as an additive in the electrolyte, which has a good effect on improving the overall electrochemical performance of the battery. By further limiting the content of siloxane compounds in these compounds to meet the above conditions, the problem of weakening the application performance of silicon-based fluorophosphate compounds in the electrolyte due to the introduction of impurities and / or hydrolysis by-products can be improved.

[0081] In some embodiments of this application, R'1 is the same as R1, R'2 is the same as R2, and R'3 is the same as R3.

[0082] In some embodiments of this application, the siloxane compound includes at least one of the following compounds: The compound shown in Formula 2-1 The compound shown in Formula 2-2 Compounds shown in Formula 2-3 Compounds shown in Formula 2-4 Compounds shown in Formula 2-5 Compounds shown in Formula 2-6 Compounds shown in Formula 2-7 Compounds shown in Formula 2-8 Compounds shown in Formula 2-9 Compounds shown in Formula 2-10 The compound shown in Formula 2-11 Compounds shown in Formula 2-12 Compounds shown in Formula 2-13 The compound shown in Formula 2-14 Compounds shown in Formula 2-15 Compounds shown in Formula 2-16 Compounds shown in Formula 2-17 Compounds shown in Formula 2-18 The compound shown in Formula 2-19 Compounds shown in Formula 2-20 Compounds shown in Formula 2-21 Compounds shown in Formula 2-22 .

[0083] In the embodiments of this application, the siloxane compounds include compounds represented by at least one of Formulas 2-1 to 2-22, which are siloxane compounds generated by the dimerization of silanol substances produced by the water decomposition of the corresponding compound represented by Formula 1.

[0084] In some embodiments of this application, the moisture content of the product in the storage or operating environment is ≤0.15 mg / cm³. 3 Under the conditions of not exceeding 100 days, based on the mass of the silicon-based fluorophosphate compound, the content of siloxane compounds m≤0.95%.

[0085] If the moisture content in the storage or operating environment of a silicon-based fluorophosphate product is too high, more silicon-based fluorophosphate compounds will decompose, increasing the content of the siloxane compound shown in Formula 2 in the product. This application embodiment, by controlling the aforementioned storage or operating conditions, helps to reduce the content of siloxane compounds, thus significantly enhancing the drag reduction effect of the silicon-based fluorophosphate compound as an additive, and more significantly improving the overall performance of the battery under high and low temperature conditions. It should be noted that the operations described herein include any operations performed after the synthesis of the compound shown in Formula 1, such as sampling operations.

[0086] In some embodiments of this application, the moisture content of the product in the storage or operating environment is ≤0.12 mg / cm³. 3 Under the conditions of not exceeding 100 days, based on the mass of the silicon-based fluorophosphate compound, the content of siloxane compounds m ≤ 0.90%.

[0087] By controlling the above storage conditions, the embodiments of this application can reduce the content of siloxane compounds, thus the drag reduction effect of the silicon-based fluorophosphate compound as an additive is obvious, and the overall performance improvement of the battery under high and low temperature conditions is more significant.

[0088] In some embodiments of this application, the product is operated or stored for no more than 100 days at a temperature not exceeding 25 °C, with the content of siloxane compounds m ≤ 0.85% based on the mass of the silicon-based fluorophosphate compound.

[0089] If the storage or operating environment of silicon-based fluorophosphate products is too hot, it will accelerate the side reactions of silicon-based fluorophosphate compounds. In the embodiments of this application, by controlling the above-mentioned operating or storage conditions, it is beneficial to reduce the content of siloxane compounds. As a result, the silicon-based fluorophosphate compound has a significant drag reduction effect as an additive, and its overall performance improvement of the battery under high and low temperature conditions is more significant.

[0090] In some embodiments of this application, the product is operated or stored for no more than 100 days at a temperature not exceeding 0 °C, with the content of siloxane compounds m ≤ 0.80% based on the mass of the silicon-based fluorophosphate compound.

[0091] In some embodiments of this application, the product is operated or stored for no more than 50 days at a temperature not exceeding 25°C, and the content of the siloxane compound m is ≤0.7% based on the mass of the silicon-based fluorophosphate compound.

[0092] Silicon-based fluorophosphate products undergo side reactions in aqueous environments and at certain temperatures; the longer the operation or storage time, the more siloxane compounds are generated. The embodiments of this application, by controlling the aforementioned operation or storage conditions and time, facilitate the reduction of siloxane compound content. Therefore, the silicon-based fluorophosphate compound, as an additive, exhibits a significant drag-reducing effect and provides a more substantial improvement in the overall battery performance under high and low temperature conditions.

[0093] In some embodiments of this application, the product is operated or stored for no more than 30 days at a temperature not exceeding 25°C, and the content of the siloxane compound m is ≤0.5% based on the mass of the siloxane compound.

[0094] By controlling the above storage conditions, the embodiments of this application can reduce the content of siloxane compounds, thus the drag reduction effect of the silicon-based fluorophosphate compound as an additive is obvious, and the overall performance improvement of the battery under high and low temperature conditions is more significant.

[0095] The second aspect of this application proposes the application of phosphate ester products in the fields of electrolytes and batteries.

[0096] The third aspect of this application provides an electrolyte comprising the aforementioned phosphate ester product.

[0097] The electrolyte provided in this application embodiment contains the above-mentioned phosphate ester product, which is beneficial to improving the performance of the silicon-based fluorophosphate ester compound shown in Formula 1.

[0098] In some embodiments of this application, the mass percentage of the phosphate ester product is 0.05% to 5.0% based on the total mass of the electrolyte.

[0099] In this embodiment, the amount of phosphate ester product provided meets the above conditions, which has a good effect on improving the overall electrochemical performance of the battery. At the same time, it avoids excessive phosphate ester product causing an excessively thick interfacial film, increasing impedance, and preventing the introduction of excessive silicon-containing impurities. Specifically, based on the total mass of the electrolyte, the mass percentage of the phosphate ester product is 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, etc. Further, based on the total mass of the electrolyte, the mass percentage of the phosphate ester product is 0.1%~3.0%; even further, based on the total mass of the electrolyte, the mass percentage of the phosphate ester product is 0.5%~2.0%.

[0100] A fourth aspect of this application provides a battery comprising the electrolyte described above.

[0101] The battery provided in this embodiment exhibits good low-temperature discharge performance, high-temperature cycling performance, and high-temperature storage stability.

[0102] In some embodiments, the battery includes an ion battery, which includes lithium-ion batteries and sodium-ion batteries.

[0103] In some embodiments, the battery includes a positive electrode, a negative electrode, a separator, and the electrolyte described above.

[0104] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0105] [Obtaining Silicate-Based Fluorophosphate Compounds] Product Example 1 100 g of the compound shown in Formula 1-1 was stored in a 250 mL container with a water content of 0.05 mg / cm³. 3 The silicon-based fluorophosphate compound was obtained by storing the compound at 25°C for 50 days.

[0106] Product Examples 2-32 It is basically the same as the product example 1, with the differences shown in Table 1.

[0107] Product Comparison Example 1 It is basically the same as the product example 1, with the differences shown in Table 1.

[0108] Table 1

[0109] The gas chromatography (GC) method was used, with acetonitrile as the solvent. The instrument was an Agilent 7890B GC equipped with an FID detector, and a Restek® RTX-65 column was used. The injection port temperature was 120°C, the detector temperature was 150°C, and the column temperature program was (initial 50°C, hold for 1 min, increase to 120°C at 5°C / min, hold for 1 min). The column flow rate was 1 mL / min. After setting the GC instrument conditions according to the parameters and obtaining a stable baseline, the sample was directly injected twice to determine the retention time of the components under these test conditions. The peak positions at RT=3.158 min and RT=3.622 min were measured by GC-MS, with the ion source temperature and interface temperature both at 260°C.

[0110] Test results are available Figure 1 As shown, the peaks at RT=3.158 min and RT=3.622 min were determined to be the impurity MM peak and the main substance peak, respectively. The sample purity and the content of siloxane compounds were calculated using the area normalization method. The test results are as follows. Figure 2 and Figure 3 As shown.

NCM523-AG System

[0111] Cathode preparation: LiNi 0.5 Co 0.2 Mn 0.3 O2 cathode material (NCM523), conductive agent SuperP (conductive carbon black), conductive agent CNT (carbon nanotubes), and binder PVDF (polyvinylidene fluoride) were mixed evenly at a mass ratio of 96.3:2:0.5:1.2 and vacuum stirred until uniform flowability was achieved. This slurry was then evenly coated onto both sides of an aluminum foil, and subsequently dried at 85 ℃, cold-pressed, trimmed, cut into sheets, slit, and vacuum-dried at 85 ℃ for 12 h. After welding the tabs, an areal density of 33 mg / cm³ was obtained. 2 The positive electrode sheet.

[0112] Negative electrode preparation: Graphite negative electrode material, conductive agent Super P (conductive carbon black), thickener CMC (sodium carboxymethyl cellulose), and binder SBR (styrene-butadiene rubber latex) were thoroughly mixed in a mass ratio of 95:1.5:1.5:2 to form a uniform slurry. After coating both sides of copper foil, the slurry was dried at 85 ℃, followed by cold pressing, edge trimming, cutting, and slitting. Finally, the slurry was dried under vacuum at 85 ℃ for 12 h, and the electrode tabs were welded to obtain a surface density of 19.3 mg / cm³. 2 The negative electrode sheet.

[0113] The diaphragm is made of a 9 μm thick porous polyethylene polymer film as the substrate, with a 2 μm thick adhesive PVDF coating on both sides of the substrate.

[0114] Lithium-ion battery manufacturing: The positive electrode, separator, and negative electrode are sequentially stacked and then wound to form a bare cell with a theoretical capacity of 1600mAh. The bare cell is placed in outer packaging aluminum foil and vacuum baked at 75 ℃ for 10 h before the electrolyte is injected. After vacuum sealing, settling, formation, aging, and capacity testing, the lithium-ion battery manufacturing process is complete.

[0115] Battery Examples 2-37 Example 2-37 uses the same method as Example 1, and the components and dosages are shown in Table 2.

[0116] Battery Comparison 1 - Battery Comparison 2 Comparative Examples 1 and 2 were performed using the same methods as in Example 1, and the components and amounts are shown in Table 2.

[0117] Table 2

[0118] II. Performance Testing 1. Testing Method (1) 25 ℃ ambient temperature cycling test: Charge the battery at 25 °C with a constant current of 1.0 C to 4.35 V, then charge it at a constant voltage of 4.35 V to the cutoff current of 0.05 C. Then discharge the battery with a constant current of 1.0 C to 2.75 V. Repeat the charge and discharge cycle for 1000 cycles. Record the discharge capacity of the 1000th cycle and the 1st cycle. Divide the two values ​​to obtain the capacity retention rate.

[0119] (2) 45 ℃ high temperature cycling test: Charge the battery at 45 °C with a constant current of 1.0 C to 4.35 V, then charge it at a constant voltage of 4.35 V to the cutoff current of 0.05 C. Then discharge the battery at a constant current of 1.0 C to 2.75 V. Repeat the charge and discharge cycle for 800 cycles. Record the discharge capacity of the 800th cycle and the 1st cycle. Divide the two values ​​to obtain the capacity retention rate.

[0120] (3) Storage test at 60 ℃ for 30 days: The battery was charged at 25 °C with a constant current of 1.0 C to 4.35 V, and then charged at a constant voltage of 4.35 V until the cutoff current was 0.05 C. It was then discharged at a constant current of 1.0 C to 2.75 V, and the discharge capacity was recorded as C1. At 25 °C, the battery was charged at a constant current of 1.0 C to 4.35 V, and then charged at a constant voltage of 4.35 V until the cutoff current was 0.05 C. The battery was then transferred to 60 °C and stored for 30 days. It was then discharged at a constant current of 1.0 C to 2.75 V, and the discharge capacity was recorded as C2. The capacity retention rate after 30 days of storage at 60 °C is calculated as C2 / C1 * 100%.

[0121] (4) -20 ℃ low temperature discharge test: The battery was charged at 25 °C with a constant current of 1.0 C to 4.35 V, and then charged at a constant voltage of 4.35 V until the cutoff current was 0.05 C. It was then discharged at a constant current of 0.5 C to 2.75 V, and the discharge capacity was recorded as C3. At 25 °C, the battery was charged at a constant current of 1.0 C to 4.35 V, and then charged at a constant voltage of 4.35 V until the cutoff current was 0.05 C. The battery was then transferred to -20 °C and left to stand for 240 min. It was then discharged at a constant current of 0.5 C to 2.75 V, and the discharge capacity was recorded as C4. The discharge rate at -20 °C = C4 / C3 * 100%.

[0122] (5) Initial DCIR (short for "Direct Current Internal Resistance") test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 4.35 V, and then charged at a constant voltage of 4.35 V to the cutoff current of 0.05 C. The battery was then discharged with a constant current of 1.0 C for 30 min, and after resting for 1 h, it was discharged with a constant current of 2.0 C for 10 s. The DCIR impedance value of the battery at 50% SOC was calculated.

[0123] (6) Low-temperature DCIR test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 4.35 V, and then charged at a constant voltage of 4.35 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, and left to stand for 1 h. The battery was then transferred to -20 °C and left to stand for 240 min. Finally, it was discharged at a constant current of 1.0 C for 10 s. The DCIR impedance value of the battery at 50% SOC was calculated.

[0124] (7) High-temperature DCIR test: A lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 4.35 V, then charged at a constant voltage of 4.35 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, allowed to rest for 1 h, and then discharged at a constant current of 2.0 C for 10 s. The DCIR at 50% SOC was calculated and recorded as D1. A battery that had completed a 30-day storage test at 60 °C was charged at 25 °C with a constant current of 1.0 C to 4.35 V, then charged at a constant voltage of 4.35 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, allowed to rest for 1 h, and then discharged at a constant current of 2.0 C for 10 s. The DCIR at 50% SOC was calculated and recorded as D2. The battery impedance change rate = D2 / D1*100%.

[0125] (8) High-temperature expansion test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 4.35 V, and then charged at a constant voltage of 4.35 V to a cutoff current of 0.05 C. The initial thickness of the lithium-ion battery at this point was measured and recorded as T1. The battery was then stored at 60 °C for 30 days, and the thickness under the 60 °C condition was measured and recorded as T2. The battery expansion rate (%) = (T2 - T1) / T1 × 100%.

[0126] 2. Performance Test Results The performance test results of the NCM523-AG system battery are shown in Table 3.

[0127] Table 3

[0128] Comparing Examples 1-22 with Comparative Example 2, it can be determined that the introduction of this structural compound can effectively improve the high and low temperature performance of the NCM523 battery system, significantly improving battery impedance reduction and cycle performance. Grafting different groups improves battery performance to varying degrees. It can be basically determined that compounds 1-1 and 1-2 have a certain advantage in improving battery performance, possibly because the grafted groups have a smaller volume and less impact on battery impedance, thus exhibiting superior electrochemical performance. Comparing Examples 23-30 verifies that the amount of this additive has a significant impact on battery performance; the recommended addition amount is 0.05-5%, exceeding this range may reduce the improvement in electrochemical performance. Comparing Examples 31-37 and the Comparative Example shows that the silicon-based structural compound remaining in this compound also has a certain negative impact on its performance. By controlling the content of the silicon-based structural compound, the overall electrochemical performance improvement of this compound can be further enhanced. Further application of the typical compound to different battery systems, such as LCO and LFP systems, shows that the compound's improvement on battery performance is basically consistent under different battery systems and different test voltages, demonstrating good adaptability to different battery systems.

[0129]

LFP-AG System

[0130] Cathode preparation: LiFePO4 cathode material (LFP), conductive agent SuperP (conductive carbon black), and binder PVDF (polyvinylidene fluoride) were mixed evenly at a mass ratio of 96:2:2 and vacuum stirred until the fluidity was uniform. The slurry was then evenly coated on both sides of aluminum foil, and successively dried at 85 ℃, cold-pressed, trimmed, cut into sheets, slit, and vacuum dried at 85 ℃ for 12 h. After welding the tabs, an areal density of 40 mg / cm³ was obtained. 2 The positive electrode sheet.

[0131] Negative electrode preparation: Graphite negative electrode material, conductive agent Super P (conductive carbon black), thickener CMC (sodium carboxymethyl cellulose), and binder SBR (styrene-butadiene rubber latex) were thoroughly mixed in a mass ratio of 95:1.5:1.5:2 to form a uniform slurry. After coating both sides of copper foil, the slurry was dried at 85 ℃, followed by cold pressing, edge trimming, cutting, and slitting. Finally, the slurry was dried under vacuum at 85 ℃ for 12 h, and the electrode tabs were welded to obtain a surface density of 18.3 mg / cm³. 2 The negative electrode sheet.

[0132] Separator: A 12μm thick porous polyethylene polymer film is used as the substrate, and a 2μm thick adhesive PVDF coating is applied to both sides of the substrate.

[0133] Lithium-ion battery manufacturing: The positive electrode, separator, and negative electrode are sequentially stacked and then wound to form a bare cell with a theoretical capacity of 1500mAh. The bare cell is placed in outer packaging aluminum foil and vacuum baked at 75 ℃ for 10 h before the electrolyte is injected. After vacuum sealing, settling, formation, aging, and capacity testing, the lithium-ion battery manufacturing process is complete.

[0134] Battery Examples 39-47 Examples 39-47 follow the same method as Example 38, and the components and dosages are shown in Table 4.

[0135] Battery Comparison 3 - Battery Comparison 4 Comparative Examples 3 and 4 were performed using the same methods as Example 35, and the components and amounts are shown in Table 4.

[0136] Table 4

[0137] II. Performance Testing 1. Performance Testing Methods (1) 25 ℃ ambient temperature cycling test: Charge the battery at 25 °C with a constant current of 1.0 C to 3.65 V, then charge it at a constant voltage of 3.65 V to the cutoff current of 0.05 C. Then discharge the battery at a constant current of 1.0 C to 2.0 V. Repeat the charge and discharge cycle for 2000 cycles. Record the discharge capacity of the 2000th cycle and the 1st cycle. Divide the two values ​​to obtain the capacity retention rate.

[0138] (2) 45 ℃ high temperature cycling test: Charge the battery at 45 °C with a constant current of 1.0 C to 3.65 V, then charge it at a constant voltage of 3.65 V to the cutoff current of 0.05 C. Then discharge the battery at a constant current of 1.0 C to 2.0 V. Repeat the charge and discharge cycle for 1000 cycles. Record the discharge capacity of the 1000th cycle and the 1st cycle. Divide the two values ​​to obtain the capacity retention rate.

[0139] (3) Storage test at 60 ℃ for 30 days: The battery was charged at 25 °C with a constant current of 1.0 C to 3.65 V, and then charged at a constant voltage of 3.65 V until the cutoff current was 0.05 C. It was then discharged at a constant current of 1.0 C to 2.0 V, and the discharge capacity was recorded as C1. At 25 °C, the battery was charged at a constant current of 1.0 C to 3.65 V, and then charged at a constant voltage of 3.65 V until the cutoff current was 0.05 C. The battery was then transferred to 60 °C and stored for 30 days. It was then discharged at a constant current of 1.0 C to 2.0 V, and the discharge capacity was recorded as C2. The capacity retention rate after 30 days of storage at 60 °C is calculated as C2 / C1 * 100%.

[0140] (4) -10 ℃ low temperature discharge test: The battery was charged at 25 °C with a constant current of 1.0 C to 3.65 V, and then charged at a constant voltage of 3.65 V until the cutoff current was 0.05 C. It was then discharged at a constant current of 0.5 C to 2.0 V, and the discharge capacity was recorded as C3. At 25 °C, the battery was charged at a constant current of 1.0 C to 3.65 V, and then charged at a constant voltage of 3.65 V until the cutoff current was 0.05 C. The battery was then transferred to -10 °C and left to stand for 240 min. It was then discharged at a constant current of 0.5 C to 2.0 V, and the discharge capacity was recorded as C4. The discharge rate at -10 °C = C4 / C3 * 100%.

[0141] (5) Initial DCIR (short for "Direct Current Internal Resistance") test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 3.65 V, and then charged at a constant voltage of 3.65 V to a cutoff current of 0.05 C. The battery was then discharged with a constant current of 1.0 C for 30 min, and after resting for 1 h, it was discharged with a constant current of 2.0 C for 10 s. The DCIR impedance value of the battery at 50% SOC was calculated.

[0142] (6) Low-temperature DCIR test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 3.65 V, and then charged at a constant voltage of 3.65 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, and left to stand for 1 h. After that, the battery was transferred to -10 °C and left to stand for 240 min. Then, it was discharged at a constant current of 0.5 C for 10 s. The DCIR impedance value of the battery at 50% SOC was calculated.

[0143] (7) High-temperature DCIR test: A lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 3.65 V, then charged at a constant voltage of 3.65 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, allowed to rest for 1 h, and then discharged at a constant current of 2.0 C for 10 s. The DCIR at 50% SOC was calculated and recorded as D1. A battery that had completed a 30-day storage test at 60 °C was charged at 25 °C with a constant current of 1.0 C to 3.65 V, then charged at a constant voltage of 3.65 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, allowed to rest for 1 h, and then discharged at a constant current of 2.0 C for 10 s. The DCIR at 50% SOC was calculated and recorded as D2. The battery impedance change rate = D2 / D1*100%.

[0144] (8) High-temperature expansion test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 3.65 V, and then charged at a constant voltage of 3.65 V to a cutoff current of 0.05 C. The initial thickness of the lithium-ion battery at this point was measured and recorded as T1. The battery was then stored at 60 °C for 30 days, and the thickness under the 60 °C condition was measured and recorded as T2. The battery expansion rate (%) = (T2 - T1) / T1 × 100%.

[0145] 2. Performance Test Results The performance test results of the LFP-AG system battery are shown in Table 5.

[0146] Table 5

[0147]

LCO-AG System

[0148] Positive electrode preparation: LiCoO2 positive electrode material (LCO), conductive agent SuperP (conductive carbon black), and binder PVDF (polyvinylidene fluoride) were mixed evenly at a mass ratio of 96.8:2:1.2 and vacuum stirred until the fluidity was uniform. The slurry was then evenly coated on both sides of aluminum foil, and successively dried at 85 ℃, cold-pressed, trimmed, cut into sheets, slit, and vacuum dried at 85 ℃ for 12 h. After welding the tabs, an areal density of 33 mg / cm³ was obtained. 2 The positive electrode sheet.

[0149] Negative electrode preparation: Graphite negative electrode material, conductive agent Super P (conductive carbon black), and binder SBR (styrene-butadiene rubber latex) are thoroughly mixed in a mass ratio of 96:1.5:2.5 to form a uniform slurry. After coating both sides of copper foil, the slurry is dried at 85 ℃, followed by cold pressing, edge trimming, cutting, and slitting. Finally, it is dried under vacuum at 85 ℃ for 12 h, and the electrode tabs are welded to obtain a surface density of 20.8 mg / cm³. 2 The negative electrode sheet.

[0150] Separator: A 12 μm thick porous polyethylene polymer film is used as the substrate, and a 2 μm thick adhesive PVDF coating is applied to both sides of the substrate.

[0151] Lithium-ion battery manufacturing: The positive electrode, separator, and negative electrode are sequentially stacked and then wound to form a bare cell with a theoretical capacity of 1700mAh. The bare cell is placed in an outer packaging aluminum foil and vacuum baked at 75 ℃ for 10 h before being injected with the electrolyte. After vacuum sealing, settling, formation, aging, and capacity testing, the lithium-ion battery manufacturing process is complete.

[0152] Battery Examples 49-57 Examples 45-53 follow the same method as Example 44, and the components and dosages are shown in Table 6.

[0153] Battery Comparison 5 - Battery Comparison 6 Comparative Examples 5 and 6 were performed using the same methods as Example 44, and the components and amounts are shown in Table 6.

[0154] Table 6

[0155] II. Performance Testing 1. Testing Method (1) 25 ℃ ambient temperature cycling test: Charge the battery at 25 °C with a constant current of 1.0 C to 4.5 V, then charge it at a constant voltage of 4.5 V to the cutoff current of 0.05 C. Then discharge the battery at a constant current of 1.0 C to 3.0 V. Repeat the charge and discharge cycle for 1000 cycles. Record the discharge capacity of the 1000th cycle and the 1st cycle. Divide the two values ​​to obtain the capacity retention rate.

[0156] (2) 45 ℃ high temperature cycling test: The battery was charged at 45 °C with a constant current of 1.0 C to 4.5 V, and then charged at a constant voltage of 4.5 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C to 3.0 V. This charge and discharge cycle was repeated for 800 cycles. The discharge capacity of the 800th cycle and the 1st cycle were recorded. The capacity retention rate was obtained by dividing the two values.

[0157] (3) Storage test at 60 ℃ for 30 days: The battery was charged at 25 °C with a constant current of 1.0 C to 4.5 V, and then charged at a constant voltage of 4.5 V until the cutoff current was 0.05 C. It was then discharged at a constant current of 1.0 C to 3.0 V, and the discharge capacity was recorded as C1. At 25 °C, the battery was charged at a constant current of 1.0 C to 4.5 V, and then charged at a constant voltage of 4.5 V until the cutoff current was 0.05 C. The battery was then transferred to 60 °C and stored for 30 days. It was then discharged at a constant current of 1.0 C to 3.0 V, and the discharge capacity was recorded as C2. The capacity retention rate after 30 days of storage at 60 °C is calculated as C2 / C1 * 100%.

[0158] (4) Low-temperature discharge test at 0 ℃: The battery was charged at 25 °C with a constant current of 1.0 C to 4.5 V, and then charged at a constant voltage of 4.5 V until the cutoff current was 0.05 C. It was then discharged at a constant current of 0.5 C to 3.0 V, and the discharge capacity was recorded as C3. At 25 °C, the battery was charged at a constant current of 1.0 C to 4.5 V, and then charged at a constant voltage of 4.5 V until the cutoff current was 0.05 C. The battery was then transferred to 0 °C and left to rest for 240 min. It was then discharged at a constant current of 0.5 C to 3.0 V, and the discharge capacity was recorded as C4. The discharge rate at 0 °C = C4 / C3 * 100%.

[0159] (5) Initial DCIR (short for "Direct Current Internal Resistance") test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 4.5 V, and then charged at a constant voltage of 4.5 V to the cutoff current of 0.05 C. The battery was then discharged with a constant current of 1.0 C for 30 min, and after resting for 1 h, it was discharged with a constant current of 2.0 C for 10 s. The DCIR impedance value of the battery at 50% SOC was calculated.

[0160] (6) Low-temperature DCIR test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 4.5 V, and then charged at a constant voltage of 4.5 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, and left to stand for 1 h. The battery was then transferred to 0 °C and left to stand for 240 min. Finally, it was discharged at a constant current of 0.5 C for 10 s. The DCIR impedance value of the battery at 50% SOC was calculated.

[0161] (7) High-temperature DCIR test: A lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 4.5 V, then charged at a constant voltage of 4.5 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, allowed to rest for 1 h, and then discharged at a constant current of 2.0 C for 10 s. The DCIR at 50% SOC was calculated and recorded as D1. A battery that had completed a 30-day storage test at 60 °C was charged at 25 °C with a constant current of 1.0 C to 4.5 V, then charged at a constant voltage of 4.5 V to a cutoff current of 0.05 C. The battery was then discharged at a constant current of 1.0 C for 30 min, allowed to rest for 1 h, and then discharged at a constant current of 2.0 C for 10 s. The DCIR at 50% SOC was calculated and recorded as D2. The battery impedance change rate = D2 / D1*100%.

[0162] (8) High-temperature expansion test: The lithium-ion battery was charged at 25 °C with a constant current of 1.0 C to 4.5 V, and then charged at a constant voltage of 4.5 V to a cutoff current of 0.05 C. The initial thickness of the lithium-ion battery at this point was measured and recorded as T1. The battery was then stored at 60 °C for 30 days, and the thickness under the 60 °C condition was measured and recorded as T2. Battery expansion rate (%) = (T2 - T1) / T1 × 100%.

[0163] 2. Performance Test Results II. Test Results.

[0164] The performance test results of the LCO-AG system battery are shown in Table 7.

[0165] Table 7

[0166] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A phosphate ester product, characterized in that, The compound includes silicon-based fluorophosphate compounds and siloxane compounds, wherein the siloxane compounds are obtained by hydrolyzing the silicon-based fluorophosphate compounds; based on the mass of the silicon-based fluorophosphate compounds, the content m of the siloxane compounds satisfies: 0 < m ≤ 1.0%; the silicon-based fluorophosphate compounds are shown in Formula 1: Formula 1; The siloxane compounds are shown in Formula 2: Formula 2; R1, R2, R3, R'1, R'2 and R'3 are each independently selected from any one of H, F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 fluoroalkenyl, C2-C4 alkynyl, C2-C4 fluoroalkynyl, C5-C7 cycloalkyl, R4-substituted phenyl and R5-substituted benzyl.

2. The phosphate ester product according to claim 1, characterized in that, Based on the mass of the silicon-based fluorophosphate compound, the content m of the siloxane compound satisfies: 1 ppm ≤ m ≤ 1.0%.

3. The phosphate ester product according to claim 1, characterized in that, R4 and R5 are each independently selected from any one of C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, C1-C4 fluoroalkyl, C2-C4 fluoroalkenyl and C2-C4 fluoroalkynyl.

4. The phosphate ester product according to claim 1, characterized in that, R1, R2, and R3 are each independently any one of C1-C2 alkyl and C2-C3 alkenyl; and / or, R4 and R5 are each independently fluorine or methyl.

5. The phosphate ester product according to claim 1, characterized in that, The silicon-based fluorophosphate compound includes at least one of the following compounds: The compound shown in Formula 1-1 Compounds shown in Formula 1-2 Compounds shown in Formulas 1-3 Compounds shown in Formulas 1-4 Compounds shown in Formulas 1-5 Compounds shown in Formulas 1-6 Compounds shown in Formulas 1-7 Compounds shown in Formulas 1-8 Compounds shown in Formulas 1-9 Compounds shown in Formula 1-10 Compounds shown in Formula 1-11 Compounds shown in Formula 1-12 Compounds shown in Formula 1-13 Compounds shown in Formula 1-14 Compounds shown in Formula 1-15 Compounds shown in Formula 1-16 Compounds shown in Formula 1-17 The compounds shown in Formula 1-18 The compounds shown in Formula 1-19 The compounds shown in Formula 1-20 The compounds shown in Formula 1-21 The compounds shown in Formula 1-22 .

6. The phosphate ester product according to any one of claims 1 to 5, characterized in that, R'1 is the same as R1, R'2 is the same as R2, and R'3 is the same as R3.

7. The phosphate ester product according to claim 1, characterized in that, The siloxane compounds include at least one of the following compounds: The compound shown in Formula 2-1 The compound shown in Formula 2-2 Compounds shown in Formula 2-3 Compounds shown in Formula 2-4 Compounds shown in Formula 2-5 Compounds shown in Formula 2-6 Compounds shown in Formula 2-7 Compounds shown in Formula 2-8 Compounds shown in Formula 2-9 Compounds shown in Formula 2-10 The compound shown in Formula 2-11 Compounds shown in Formula 2-12 Compounds shown in Formula 2-13 The compound shown in Formula 2-14 Compounds shown in Formula 2-15 Compounds shown in Formula 2-16 Compounds shown in Formula 2-17 Compounds shown in Formula 2-18 The compound shown in Formula 2-19 Compounds shown in Formula 2-20 Compounds shown in Formula 2-21 Compounds shown in Formula 2-22 .

8. The phosphate ester product according to claim 1, characterized in that, The product has a moisture content of ≤0.15 mg / cm³ in the storage or operating environment. 3 Under the condition that the time does not exceed 100 days, the content of the siloxane compound m is ≤0.95% based on the mass of the siloxane compound.

9. The phosphate ester product according to claim 8, characterized in that, The product has a moisture content of ≤0.12 mg / cm³ in the storage or operating environment. 3 Under the condition that the time does not exceed 100 days, the content of the siloxane compound m is ≤0.9% based on the mass of the siloxane compound.

10. The phosphate ester product according to claim 8, characterized in that, The product is operated or stored for no more than 100 days at a temperature not exceeding 25 ℃, and the content of the siloxane compound m is ≤0.85% based on the mass of the silicon-based fluorophosphate compound.

11. The phosphate ester product according to claim 10, characterized in that, The product is operated or stored for no more than 100 days at a temperature not exceeding 0 ℃, with the content of the siloxane compound m ≤ 0.8% based on the mass of the silicon-based fluorophosphate compound.

12. The phosphate ester product according to claim 10, characterized in that, The product is operated or stored for no more than 50 days at a temperature not exceeding 25°C, and the content of the siloxane compound m is ≤0.7% based on the mass of the silicon-based fluorophosphate compound.

13. The phosphate ester product according to claim 11, characterized in that, The product is operated or stored for no more than 30 days at a temperature not exceeding 25°C, and the content of the siloxane compound m is ≤0.5% based on the mass of the silicon-based fluorophosphate compound.

14. The use of the phosphate ester product according to any one of claims 1 to 13 in the field of electrolytes and batteries.

15. An electrolyte, characterized in that, It includes the phosphate ester product according to any one of claims 1 to 13.

16. The electrolyte according to claim 15, characterized in that, Based on the total mass of the electrolyte, the mass percentage of the phosphate ester product is 0.05% to 5.0%.

17. A battery, characterized in that, It includes the electrolyte as described in claim 15 or 16.

Images