Cyclic carbonate-sulfate compounds, methods of making the same, and nonaqueous electrolytes

Abstract

To overcome the problems of unstable SEI film at the negative electrode interface and reduced rate discharge capacity retention caused by solvation of electrolytes in some batteries, this invention provides a cyclic carbonate-sulfate compound, its preparation method, and a non-aqueous electrolyte. The cyclic carbonate-sulfate compound includes the compound shown in Chemical Formula 1, and the compound shown in Chemical Formula 1 includes 99 wt% or more of the compound shown in Structural Formula 1. The specific rotation of the cyclic carbonate-sulfate compound is […]. α The value is above -6.228. The cyclic carbonate-sulfate compound provided in this application can weaken the solvation effect of metal ions (such as lithium ions) and EC, inhibit the co-intercalation of the solvent and the decomposition of the electrolyte, so as to stabilize the structure of the SEI film (solid electrolyte membrane) formed at the negative electrode interface, and improve the battery's rate discharge capacity retention rate and high temperature performance.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to a cyclic carbonate-sulfate compound and its preparation method, as well as a non-aqueous electrolyte. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems due to their high energy density, portability, and recyclability. A lithium-ion battery mainly consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, lithium ions move back and forth between the positive and negative electrodes via the electrolyte, intercalating and deintercalating to store and release electrical energy. The electrolyte plays a crucial role in lithium-ion batteries, serving as the medium for lithium-ion transport. Electrolytes are typically composed of lithium salts and organic solvents. In the electrolyte, lithium ions react with organic solvents such as EC (electrolyte-enzyme) to form solvated structures. These solvated structures significantly influence the transport dynamics of lithium ions within the battery.

[0003] The solvation structure formed by lithium ions and organic solvent molecules allows lithium ions to move more effectively in the electrolyte. Simultaneously, on the surface of the graphite anode material, solvated lithium ions can undergo orderly desolvation and intercalation, resulting in a more stable and efficient electrode reaction, which is beneficial for normal battery operation. However, if solvation is too strong, solvent molecules tightly surround lithium ions, causing them to carry solvent molecules along with them during transport, hindering lithium ion transport in the electrolyte. Furthermore, excessive solvation can lead to solvent co-intercalation, where solvent molecules and ions (such as lithium ions) intercalate together into the crystal structure of the electrode material. This disrupts the crystal structure, causing graphite sheet peeling, instability of the SEI film at the anode interface, and reduced battery capacity retention during high-rate discharge. Summary of the Invention

[0004] To address the problem that the solvation of electrolytes in some batteries leads to instability of the SEI film at the negative electrode interface and a decrease in the rate discharge capacity retention rate of the battery, this invention provides a cyclic carbonate-sulfate compound, its preparation method, and a non-aqueous electrolyte.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a cyclic carbonate-sulfate compound comprising the compound shown in Formula 1, wherein the compound shown in Formula 1 comprises 99 wt% or more of the compound shown in Formula 1. The specific rotation of the cyclic carbonate-sulfate compound [ αThe value is -6.228. above.

[0006] Preferably, in the cyclic carbonate-sulfate compound, the content of the compound represented by Formula 1 is ≥99 wt%.

[0007] Preferably, the compound represented by Formula 1 further includes stereoisomer impurities, and the content of the stereoisomer impurities in the compound represented by Formula 1 is ≤1 wt%. And / or, the chlorine content in the cyclic carbonate-sulfate compound is ≤100ppm.

[0008] Preferably, the cyclic carbonate-sulfate compound further includes organic impurities, the content of which is ≤1 wt%. The organic impurities include one or more of the following compounds: .

[0009] Preferably, the specific rotation [ α The test conditions were: wavelength 589 nm, temperature 25 degrees Celsius, solvent acetone, test tube length 100 mm, and concentration of cyclic carbonate-sulfate compound 0.151 g / mL.

[0010] Secondly, this application provides a method for preparing the above-mentioned cyclic carbonate-sulfate compound, comprising the following steps: A carbonate polyol intermediate is obtained by mixing and reacting hexahydrol, low alcohol, and carbonate compounds. The carbonate polyol intermediate, sulfonyl compound, and basic compound are then reacted to obtain crude cyclic carbonate-sulfate. The crude cyclic carbonate-sulfate is then post-treated to obtain the cyclic carbonate-sulfate compound. The hexaol includes the compound shown in structural formula 2 (2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexaol, CAS: CAS488-44-8): Structural Formula 2; The low alcohol comprises at least one of a monohydric alcohol and a dihydric alcohol, wherein the monohydric alcohol comprises C n H 2n+1 OH, n is 1~4; the diol includes C m H 2m+2 O2, m is 1~4; The sulfonyl compounds include sulfonyl chlorides; The carbonate compounds include one or more of cyclic carbonates and chain carbonates; The cyclic carbonates include ethylene carbonate, and the chain carbonates include one or more of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, and diphenyl carbonate. The alkaline compound includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert-butoxide, triethylamine, and pyridine.

[0011] Preferably, the molar ratio of the hexahydrol to the lower alcohol is 1:(5~15). The molar ratio of the hexahydrol to the carbonate compound is 1:(10~15). The molar ratio of the carbonate polyol intermediate to the sulfonyl compound is 1:(1.8~3). The mass ratio of the carbonate polyol intermediate to the basic compound is 1:(2~3.5).

[0012] Preferably, the reaction temperature of the mixed reaction is 60~120℃, and the reaction time of the mixed reaction is 2~12h; The reaction temperature in the step of reacting the carbonate polyol intermediate, sulfonyl compound and basic compound to obtain the crude product is -78~10℃, and the reaction time is 1~4h. And / or, the post-processing includes the following steps: recrystallizing the crude product using an alcohol solution to obtain the cyclic carbonate-sulfate compound.

[0013] Thirdly, this application provides a non-aqueous electrolyte comprising a non-aqueous organic solvent, an electrolyte salt, and additives, wherein the additives include the aforementioned cyclic carbonate-sulfate compounds.

[0014] Preferably, the mass percentage of the cyclic carbonate-sulfate compound is 0.05% to 10% based on the total mass of the non-aqueous electrolyte (100%).

[0015] The cyclic carbonate-sulfate compound provided in this application has an optical rotation of […]. α The value is -6.228. When the above conditions are met, the compound has higher spatial structural symmetry, which is beneficial for the battery formation stage, forming a regular and stable solid electrolyte interface film on the positive and negative electrode surfaces, thereby improving the electrochemical performance of the secondary battery.

[0016] Cyclic carbonate-sulfate compounds include the compounds shown in Formula 1, and the compounds shown in Formula 1 include 99 wt% or more of the compounds shown in Structural Formula 1. All rings of the compounds shown in Structural Formula 1 are in the same plane, and the stacking of the -SO2- and -CO- groups in the compounds shown in Structural Formula 1 with metal ions (such as lithium ions) is relatively loose and appropriate, avoiding the loose or tight stacking of metal ions (such as lithium ions). At the same time, it can weaken the solvation effect of metal ions (such as lithium ions) and EC, inhibit the co-intercalation of solvent and electrolyte decomposition, avoid the shedding of the negative electrode material layer of the battery, make the SEI film (solid electrolyte membrane) formed at the negative electrode interface structurally stable, have a good metal ion migration rate, and improve the battery's rate discharge capacity retention rate and high temperature performance. Attached Figure Description

[0017] Figure 1 This is the 1H NMR spectrum of the cyclic carbonate-sulfate compound provided in Example 1 of this invention. The deuterated reagent is deuterated DMSO. (The horizontal axis f1 (ppm) in the figure represents the chemical shift, and the vertical axis represents the absorption peak intensity, the same below).

[0018] Figure 2 The carbon NMR spectrum of the cyclic carbonate-sulfate compound provided in Example 1 of this invention ( 13 CNMR), deuterated reagent: deuterated DMSO. Detailed Implementation

[0019] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0020] In a first aspect, this application provides a cyclic carbonate-sulfate compound comprising the compound shown in Formula 1, wherein the compound shown in Formula 1 comprises 99 wt% or more of the compound shown in Structural Formula 1. The specific rotation of the cyclic carbonate-sulfate compound [ α The value is -6.228. above.

[0021] Specifically, optical rotation [ α The value is -6.228. When the above conditions are met, the compound has higher spatial structural symmetry, which is beneficial for the battery formation stage, forming a regular and stable solid electrolyte interface film on the positive and negative electrode surfaces, thereby improving the electrochemical performance of the secondary battery.

[0022] Cyclic carbonate-sulfate compounds include the compounds shown in Formula 1, and the compounds shown in Formula 1 include 99 wt% or more of the compounds shown in Structural Formula 1. All rings of the compounds shown in Structural Formula 1 are in the same plane, and the stacking of the -SO2- and -CO- groups in the compounds shown in Structural Formula 1 with metal ions (such as lithium ions) is relatively loose and appropriate, avoiding the loose or tight stacking of metal ions (such as lithium ions). At the same time, it can weaken the solvation effect of metal ions (such as lithium ions) and EC, inhibit the co-intercalation of solvent and electrolyte decomposition, avoid the shedding of the negative electrode material layer of the battery, make the SEI film (solid electrolyte membrane) formed at the negative electrode interface structurally stable, have a good metal ion migration rate, and improve the battery's rate discharge capacity retention rate and high temperature performance.

[0023] Among them, solvent co-intercalation refers to the insertion of solvent molecules and metal ions (such as lithium ions) into the electrode material together. This may damage the electrode structure, cause the negative electrode material layer of the battery to fall off, affect the formation of the negative electrode interface film, and affect the battery's rate discharge capacity retention rate and high temperature performance.

[0024] In the spatial structure of cyclic sulfate esters, if all the ring planes of the compound shown in Formula 1 are not in the same direction, metal ions such as lithium ions may be loosely packed with the -SO2- and -CO- groups in the compound shown in Formula 1. This may weaken the solvation effect between lithium ions and EC, making the compound shown in Formula 1 unable to effectively compete with EC and metal ions for solvation. Alternatively, lithium ions may be too tightly packed with the -SO2- and -CO- groups in the compound shown in Formula 1, making it difficult for lithium ions to move and increasing the migration resistance of lithium ions.

[0025] In the compound represented by chemical formula 1, the mass content of the compound represented by structural formula 1 is ≥99wt%. It contains fewer impurities, and the absolute value of the optical rotation of the cyclic carbonate-sulfate compound is smaller, which is beneficial during the battery formation stage, enabling the formation of a regular and stable solid electrolyte interface film on the positive and negative electrode surfaces, thereby improving the electrochemical performance of the secondary battery. In the compound represented by chemical formula 1, the mass content of the compound represented by structural formula 1 can be 99wt%, 99.2wt%, 99.4wt%, etc.

[0026] If the mass content of the compound shown in chemical formula 1 and the compound shown in structural formula 1 is less than 99 wt%, the solvation effect of metal ions and EC is reduced, and the solvent co-intercalation and electrolyte decomposition cannot be well suppressed, resulting in a low rate discharge capacity retention rate of the battery.

[0027] In some embodiments, the content of the compound represented by Formula 1 in the cyclic carbonate-sulfate compound is ≥99 wt%.

[0028] In cyclic carbonate-sulfate compounds, a content of ≥99wt% of the compound shown in Formula 1 is beneficial for weakening the solvation effect of metal ions (such as lithium ions) and electrolytes (ECs), inhibiting solvent co-intercalation and electrolyte decomposition, and improving the battery's rate discharge capacity retention and high-temperature performance. If the content of the compound shown in Formula 1 is less than 99wt%, the excessive organic impurities are detrimental to the uniformity of solid electrolyte film formation on the positive and negative electrode surfaces, leading to problems such as uneven solid electrolyte film thickness and degrading battery performance.

[0029] In some embodiments, the content of the compound represented by structural formula 1 in the cyclic carbonate-sulfate compound is ≥98 wt%.

[0030] Specifically, in the cyclic carbonate-sulfate compound, the content of the compound shown in Structural Formula 1 can be 98%, 98.4%, 98.5%, 99%, 99.6%, 99.8%, etc. Different contents of the compound shown in Structural Formula 1 result in different specific rotations of the cyclic carbonate-sulfate compound. For example, when the content of the compound shown in Structural Formula 1 is 98%, the specific rotation of the cyclic carbonate-sulfate compound is -6.228. When the content of the compound shown in structural formula 1 is 98.4%, the specific rotation of the cyclic carbonate-sulfate compound is -6.121. When the content of the compound shown in structural formula 1 is 99%, the specific rotation of the cyclic carbonate-sulfate compound is -6.017. When the content of the compound shown in structural formula 1 is 99.6%, the specific rotation of the cyclic carbonate-sulfate compound is -5.8997. When the content of the compound shown in structural formula 1 is 99.8%, the specific rotation of the cyclic carbonate-sulfate compound is -5.631. .

[0031] In cyclic carbonate-sulfate compounds, the content of the compound shown in structural formula 1 is ≥98wt%, resulting in a more regular and stable solid electrolyte film formed at the negative electrode interface, which improves the battery's rate discharge capacity retention rate and high-temperature performance.

[0032] In some embodiments, the compound represented by Formula 1 further includes stereoisomer impurities, wherein the content of the stereoisomer impurities in the compound represented by Formula 1 is ≤1 wt%. Specifically, the stereoisomer impurities mainly come from two sources: one is the stereoisomer impurities contained in the raw materials, and the other is the impurities generated during the preparation process. The content of stereoisomer impurities has a significant impact on the specific rotation of cyclic carbonate-sulfate compounds.

[0033] In a preferred embodiment, the content of stereoisomer impurities is ≤0.5wt%.

[0034] In some embodiments, the chlorine content in the cyclic carbonate-sulfate compound is ≤100ppm.

[0035] The source of chlorine is mainly due to chlorine-containing impurities carried in the reaction raw materials or solvents, such as sulfonyl chloride. The presence of chlorine in the cyclic carbonate-sulfate compound has a significant impact on its performance as an electrolyte additive. Although chlorine is usually formed as a substituent in the impurities of the cyclic carbonate-sulfate compound, under electrochemical conditions, chlorine-containing impurities are unstable and easily decompose to form free chlorine. Free chlorine in non-aqueous electrolytes can easily induce corrosion of the positive electrode current collector and also easily lead to the dissolution of transition metal ions in the positive electrode material. Therefore, it is necessary to control the chlorine content in the cyclic carbonate-sulfate compound to reduce its impact.

[0036] In some embodiments, the cyclic carbonate-sulfate compound further includes organic impurities, the content of which is ≤1 wt%. The organic impurities include one or more of the following compounds: .

[0037] Organic impurities also include impurities from unreacted raw materials, such as unreacted 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexaol structures, or stereoisomer impurities inherent in the raw materials themselves.

[0038] In cyclic carbonate-sulfate compounds, organic impurities are detrimental to the uniformity of solid electrolyte film formation on both positive and negative electrode surfaces, resulting in defects on the solid electrolyte film and causing problems such as uneven thickness of the solid electrolyte film. By controlling the purification conditions and reaction yield, the content of the organic impurities can be reduced, which helps to reduce defects on the solid electrolyte film, ensure the thermal shock resistance and structural stability of the solid electrolyte film, and improve the high-temperature performance and rate discharge capacity retention of the battery.

[0039] In a preferred embodiment, the specific rotation of the cyclic carbonate-sulfate compound [ α The value is -6.228. ~-6.121 .

[0040] In a more preferred embodiment, the specific rotation of the cyclic carbonate-sulfate compound [ α The value is -6.017. ~-5.8997 .

[0041] In a more preferred embodiment, the specific rotation of the cyclic carbonate-sulfate compound [ α The value is -5.8997. ~-5.631 .

[0042] In some embodiments, the specific rotation [ α The test conditions were: wavelength 589 nm, temperature 25 degrees Celsius, solvent acetone, test tube length 100 mm, and concentration of cyclic carbonate-sulfate compound 0.151 g / mL.

[0043] Secondly, this application provides a method for preparing the above-mentioned cyclic carbonate-sulfate compound, comprising the following steps: A carbonate polyol intermediate is obtained by mixing and reacting hexahydrol, low alcohol, and carbonate compounds. The carbonate polyol intermediate, sulfonyl compound, and basic compound are then reacted to obtain crude cyclic carbonate-sulfate. The crude cyclic carbonate-sulfate is then post-treated to obtain the compound shown in the cyclic carbonate-sulfate compound. The hexaol includes 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexaol.

[0044] The method for preparing cyclic carbonate-sulfate compounds provided in this application first involves a carbonate compound undergoing an ester exchange reaction with a hexahydrol to obtain a carbonate polyol intermediate. Since the hexahydrol has multiple hydroxyl groups located on different carbons, the carbonate will exchange with any one of these hydroxyl groups during the ester exchange reaction, resulting in different types of reaction products. This leads to reduced product yield and difficulties in subsequent purification. Therefore, this preparation method incorporates a low-hydroxyl group. In the presence of the low-hydroxyl group, the reactivity of the hydroxyl groups on the two middle carbons in the ester exchange reaction is greatly enhanced, while the reactivity of the hydroxyl groups on both sides of the hexahydrol is suppressed. This ensures that the prepared reaction product is primarily a carbonate polyol, significantly improving the reaction yield and reducing purification difficulty. Subsequently, the carbonate polyol intermediate, a sulfonyl compound, and a basic compound are reacted to obtain the cyclic carbonate-sulfate compound.

[0045] In some embodiments, the 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexahydrol is the compound shown in structural formula 2 (CAS: CAS488-44-8): Structural formula 2.

[0046] The method for preparing the cyclic carbonate-sulfate compound provided in this application involves reacting the compound shown in structural formula 2 with a carbonate compound to obtain a carbonate polyol intermediate. The carbonate polyol intermediate, a sulfonyl compound, and a basic compound are then reacted and post-treated to obtain the cyclic carbonate-sulfate compound. The cyclic carbonate-sulfate compound contains a large amount of the compound shown in structural formula 1.

[0047] In some embodiments, the carbonate polyol intermediate is the compound shown in structural formula 3: Structural formula 3.

[0048] In some embodiments, the low alcohol comprises at least one of a monohydric alcohol and a dihydric alcohol, wherein the monohydric alcohol comprises C n H 2n+1 OH, n is 1~4; the diol includes C m H 2m+2 O2, m is 1~4.

[0049] Specifically, monohydric alcohols include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, etc. Dihydric alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, etc.

[0050] In a preferred embodiment, the monohydric alcohol includes methanol.

[0051] In some embodiments, the molar ratio of the hexahydrol to the lower alcohol is 1:(5~15).

[0052] In the transesterification reaction, the low alcohol promotes the reactivity of the hydroxyl group at the middle position of the hexahydrol and inhibits the reactivity of the hydroxyl groups at both ends of the hexahydrol, thus suppressing side reactions. When the amount of low alcohol added is too low, it is difficult to guarantee the inhibition of side reactions, leading to reactions between hydroxyl groups at non-predetermined positions and carbonate compounds, forming a large number of unnecessary byproducts. However, since the low alcohol itself is also a reaction product of carbonates and hexahydrols, when the amount of low alcohol added is too high, it will inhibit the forward reaction, resulting in a longer reaction time and affecting production efficiency.

[0053] The molar ratio of hexahydrol to lower alcohol can be in the following ranges: 1:(5~8), 1:(8~10), 1:(10~12) or 1:(12~15).

[0054] In some embodiments, the carbonate compounds include one or more of cyclic carbonates and chain carbonates; The cyclic carbonates include ethylene carbonate, and the chain carbonates include one or more of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, and diphenyl carbonate.

[0055] In some preferred embodiments, the carbonate compound includes dimethyl carbonate.

[0056] In some embodiments, the molar ratio of the hexahydrol to the carbonate compound is 1:(10~15).

[0057] The theoretical molar ratio of carbonate compounds to hexahydrols is (10~15):1. In this preparation method, adding an excess of carbonate compounds is beneficial to accelerating the reaction; however, the amount of carbonate compounds added should not be too high, as excessive amounts of carbonate compounds can easily lead to an increase in the substitution probability of hydroxyl groups at both positions, resulting in impurities.

[0058] The molar ratio of hexahydrol to carbonate compound can be in the following ranges: 1:(10~11), 1:(11~13), 1:(13~14) or 1:(14~15).

[0059] In some embodiments, the sulfonyl compound includes sulfonyl chloride.

[0060] Sulfonyl compounds are a class of compounds containing sulfonyl groups (-SO2-) that can react with carbonate polyol intermediates to form the compound shown in structural formula 1.

[0061] In some embodiments, the molar ratio of the carbonate polyol intermediate to the sulfonyl compound is 1:(1.8~3).

[0062] In some embodiments, the alkaline compound includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert-butoxide, triethylamine, and pyridine.

[0063] The addition of basic compounds helps to improve the reactivity between carbonate polyol intermediates and sulfonyl chlorides.

[0064] In some embodiments, the mass ratio of the carbonate polyol intermediate to the basic compound is 1:(2~3.5).

[0065] When the amount of the alkaline compound added is within the above range, it is beneficial to ensure the alkaline environment required for the reaction to proceed, while avoiding the problems of subsequent purification difficulties and impurity introduction caused by excessive addition.

[0066] In some embodiments, the reaction temperature of the mixed reaction is -60 to 120°C. When the reaction temperature of the mixed reaction is within this range, it is beneficial to maintain a high reaction rate while avoiding excessively high temperatures that could increase the reactivity of the terminal hydroxyl groups of the hexaol, leading to side reactions.

[0067] Specifically, the reaction temperature of the mixed reaction can be in the following ranges: 60~70℃, 70~80℃, 80~100℃, or 100~120℃.

[0068] In some embodiments, the reaction time of the mixed reaction is 2 to 12 hours.

[0069] The reaction time can be adjusted according to the actual reaction rate. If the reaction time of the hexahydrol, lower alcohols, and carbonate compounds is too short, it will affect the reaction yield and cause waste of raw materials; if the reaction time is too long, it will affect the production efficiency and will not have a significant effect on improving the yield. Specifically, the reaction time of the mixture can be within the following ranges: 2-4 h, 4-6 h, 6-8 h, 8-10 h, or 10-12 h.

[0070] In some embodiments, the reaction temperature in the step of reacting the carbonate polyol intermediate, sulfonyl compound and basic compound to obtain crude cyclic carbonate-sulfate is -78~10℃, and the reaction time is 1~4h.

[0071] When the reaction temperature is within the range of -78 to 10℃ and the reaction time is within the range of 1 to 4 hours, the reaction of carbonate polyol intermediates and sulfonyl compounds under the action of alkaline compounds is facilitated to generate the compound shown in structural formula 1.

[0072] In some embodiments, the post-processing includes the following step: recrystallizing the crude cyclic carbonate-sulfate product using an alcohol solution to obtain the cyclic carbonate-sulfate compound.

[0073] Specifically, after the reaction of carbonate polyol intermediate, sulfonyl compound and basic compound is completed, crude cyclic carbonate-sulfate is obtained. Then, the crude cyclic carbonate-sulfate is recrystallized using an alcohol solution to obtain cyclic carbonate-sulfate compound.

[0074] In some embodiments, the alcohol solution includes a mixture of methanol and isopropanol.

[0075] In alcohol solutions, the mass ratio of methanol to isopropanol is (5~8):(1~3).

[0076] More preferably, the mass ratio of methanol to isopropanol is 6~7:1~3.

[0077] Thirdly, this application provides a non-aqueous electrolyte comprising a non-aqueous organic solvent, an electrolyte salt, and additives, wherein the additives include cyclic carbonate-sulfate compounds as described above.

[0078] By employing the cyclic carbonate-sulfate compound described above, the solvation effect of metal ions (such as lithium ions) and EC can be weakened, the solvent co-intercalation and electrolyte decomposition can be suppressed, the negative electrode material layer of the battery can be prevented from falling off, the SEI film (solid electrolyte membrane) structure of the negative electrode interface can be effectively maintained, the metal ion migration rate can be good, and the battery rate discharge capacity retention rate and high temperature performance can be improved.

[0079] In some embodiments, the mass percentage of the cyclic carbonate-sulfate compound is 0.05% to 10% based on the total mass of the non-aqueous electrolyte (100%).

[0080] In specific embodiments, based on the total mass of the non-aqueous electrolyte as 100%, the mass percentage of the cyclic carbonate-sulfate compound can be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, or 10%, etc.

[0081] When the content of cyclic carbonate-sulfate compounds is in the range of 0.05% to 10%, it can effectively maintain the stability of the film formed on the electrode surface and improve battery performance. If the content of cyclic carbonate-sulfate compounds is too low, it will be difficult to significantly improve the performance of the battery. If the content of cyclic carbonate-sulfate compounds is too high, it may affect the function of other substances in the electrolyte due to the excessive decomposition products.

[0082] In some preferred embodiments, the mass percentage of the cyclic carbonate-sulfate compound is 0.1% to 5% based on the total mass of the non-aqueous electrolyte (100%).

[0083] In some embodiments, the non-aqueous electrolyte further includes auxiliary additives, which include at least one of cyclic sulfate compounds, sulfonyl lactone compounds, cyclic carbonate compounds, phosphate compounds, borate compounds, and nitrile compounds.

[0084] In a preferred embodiment, the cyclic sulfate compound is selected from vinyl sulfate, 4-methylvinyl sulfate, propylene sulfate, etc. , , At least one of them; The sulfonyl lactone compounds are selected from methylene disulfonate, 1,3-propanesulfonyl lactone, 1,4-butanesulfonyl lactone, 1,3-propenesulfonyl lactone, etc. At least one of them; The cyclic carbonate compound is selected from at least one of ethylene carbonate, fluoroethylene carbonate, or the compound shown in structural formula 4. Structural Formula 4; In structural formula 4, R 21 R 22 R 23 R 24 R 25 R 26 Each is independently selected from one of the following: hydrogen atom, halogen atom, or C1-C5 group; More preferably, the compound shown in structural formula 4 includes at least one of the compounds shown in compounds 4-1 to 4-6 below: The phosphate ester compound is selected from at least one of tris(trimethylsilane) phosphate and the compound shown in structural formula 5: Structural formula 5; In structural formula 5, R 31 R 32 R 32 Each is independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halohydrocarbon groups, and -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 31 R 32 R 33 At least one of them is an unsaturated hydrocarbon group.

[0085] In a preferred embodiment, the unsaturated phosphate compound may be at least one of tris(trimethylsilane) phosphate, triargyl phosphate, diargylmethyl phosphate, diargylethyl phosphate, diargylpropyl phosphate, diargyltrifluoromethyl phosphate, diargyl-2,2,2-trifluoroethyl phosphate, diargyl-3,3,3-trifluoropropyl phosphate, diargylhexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, and diallyl hexafluoroisopropyl phosphate.

[0086] The borate esters are selected from tris(trimethylsilane)borate ester and tris(triethylsilane)borate ester.

[0087] The nitrile compound is selected from one or more of succinic acid, glutaronitrile, ethylene glycol bis(propionitrile) ether, hexanetrionitrile, adiponitrile, heptanonitrile, octanilide, nonadionitrile, and sebaconitrile.

[0088] In other embodiments, the auxiliary additives may also include other additives that can improve battery performance: for example, additives that improve battery safety performance, such as flame retardant additives like fluorophosphates and cyclophosphonitriles, or overcharge prevention additives like tert-amylbenzene and tert-butylbenzene.

[0089] In some embodiments, the amount of auxiliary additives added is 0.01% to 30% based on the total mass of the non-aqueous electrolyte as 100%.

[0090] It should be noted that, unless otherwise specified, the amount of any one of the optional substances in the auxiliary additives added to the non-aqueous electrolyte is generally less than 10%, preferably 0.1-5%, and more preferably 0.1% to 2%. Specifically, the amount of any one of the optional substances in the auxiliary additives can be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, or 10%, etc.

[0091] In some embodiments, when the auxiliary additive is selected from fluoroethylene carbonate, the amount of fluoroethylene carbonate added is 0.05% to 30% based on the total mass of the non-aqueous electrolyte as 100%.

[0092] In some embodiments, the mass content of the non-aqueous organic solvent is 65% to 90% based on the total mass of the non-aqueous electrolyte being 100%.

[0093] Specifically, based on the total mass of the non-aqueous electrolyte as 100%, the mass content of the non-aqueous organic solvent can be 65%, 68%, 71%, 74%, 76%, 78%, 79%, 80%, 81.5%, 82%, 84%, 85%, 86%, 87%, 89%, or 90%, etc.

[0094] In the non-aqueous electrolyte, compared with single addition or combination of other existing additives, the compound shown in structural formula 1, when added together with the auxiliary additive, exhibits a significant synergistic effect in improving battery performance. This indicates that the compound shown in structural formula 1 and the auxiliary additive, when forming a film together on the electrode surface, can compensate for the film formation defects of single addition and obtain a more stable passivation film.

[0095] In some embodiments, the non-aqueous organic solvent includes at least one of ether solvents, nitrile solvents, carbonate solvents, carboxylic acid ester solvents, and sulfone solvents.

[0096] In some embodiments, the ether solvent includes cyclic ethers or chain ethers, preferably chain ethers with 3 to 10 carbon atoms and cyclic ethers with 3 to 6 carbon atoms. The cyclic ether can be, but is not limited to, at least one of 1,3-dioxane (DOL), 1,4-dioxane (DX), crown ethers, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH3-THF), and 2-trifluoromethyltetrahydrofuran (2-CF3-THF). The chain ether can be, but is not limited to, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether. Because chain ethers have high solvation ability with lithium ions and can improve ion dissociation, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane, which have low viscosity and can impart high ionic conductivity, are particularly preferred. Ether compounds can be used alone or in any combination and ratio of two or more. There are no special restrictions on the amount of ether compounds added. It can be arbitrary as long as it does not significantly impair the effect of the high-pressure lithium-ion battery of the present invention. When the volume ratio of non-aqueous solvent is 100%, the volume ratio is usually 1% or more, preferably 2% or more, and more preferably 3% or more. In addition, the volume ratio is usually 30% or less, preferably 25% or less, and more preferably 20% or less.

[0097] In some embodiments, the nitrile solvent may be, but is not limited to, at least one of acetonitrile, glutaronitrile, and malononitrile.

[0098] In some embodiments, the carbonate solvent includes cyclic carbonates or chain carbonates. Cyclic carbonates may specifically include, but are not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and butylene carbonate (BC); chain carbonates may specifically include, but are not limited to, at least one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and dipropyl carbonate (DPC). The content of cyclic carbonates is not particularly limited and is arbitrary within a range that does not significantly impair the performance of the lithium-ion battery of the present invention. However, when using only one type, its content is typically 3% or more, preferably 5% or more, by volume relative to the total amount of solvent in the non-aqueous electrolyte. By setting this range, a decrease in conductivity due to a decrease in the dielectric constant of the non-aqueous electrolyte can be avoided, making it easier to achieve good high-current discharge characteristics, stability relative to the negative electrode, and cycle characteristics of the non-aqueous electrolyte battery. Furthermore, the upper limit is typically 90% or less by volume, preferably 85% or less, and more preferably 80% or less by volume. By setting this range, the oxidation / reduction resistance of the non-aqueous electrolyte can be improved, thereby contributing to enhanced stability during high-temperature storage. The content of the chain carbonate is not particularly limited, but relative to the total amount of solvent in the non-aqueous electrolyte, it is typically 15% or more by volume, preferably 20% or more, and more preferably 25% or more. Furthermore, it is typically 90% or less by volume, preferably 85% or less, and more preferably 80% or less. By keeping the chain carbonate content within the above range, it is easier to achieve an appropriate viscosity for the non-aqueous electrolyte, suppressing the decrease in ionic conductivity, and thus contributing to achieving a good range of output characteristics for the non-aqueous electrolyte battery. When using two or more chain carbonates in combination, it is sufficient to ensure that the total amount of chain carbonate meets the above range.

[0099] In some embodiments, fluorine-containing chain carbonates (hereinafter referred to as "fluorinated chain carbonates") are also preferably used. There is no particular limitation on the number of fluorine atoms in a fluorinated chain carbonate as long as it is 1 or more, but it is generally 6 or less, preferably 4 or less. When a fluorinated chain carbonate has multiple fluorine atoms, these fluorine atoms can be bonded to the same carbon atom or to different carbon atoms. Examples of fluorinated chain carbonates include dimethyl fluorinated carbonate derivatives, methyl ethyl fluorinated carbonate derivatives, and diethyl fluorinated carbonate derivatives.

[0100] Carboxylic acid ester solvents include cyclic carboxylic acid esters and / or chain carbonates. Examples of cyclic carboxylic acid esters include at least one of γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Examples of chain carbonates include at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate.

[0101] In some embodiments, the sulfone solvent includes cyclic sulfones and chain sulfones. Preferably, in the case of cyclic sulfones, it is typically a compound with 3 to 6 carbon atoms, more preferably 3 to 5 carbon atoms; in the case of chain sulfones, it is typically a compound with 2 to 6 carbon atoms, more preferably 2 to 5 carbon atoms. There are no particular limitations on the amount of sulfone solvent added, and it is arbitrary within a range that does not significantly impair the performance of the lithium-ion battery of the present invention. Relative to the total amount of solvent in the non-aqueous electrolyte, it is typically 0.3% or more by volume, preferably 0.5% or more by volume, more preferably 1% or more by volume. Furthermore, it is typically 40% or less by volume, preferably 35% or less by volume, more preferably 30% or less by volume. When using two or more sulfone solvents in combination, the total amount of sulfone solvent should satisfy the above range. When the amount of sulfone solvent added is within the above range, a non-aqueous electrolyte with excellent high-temperature storage stability is tended to be obtained.

[0102] In a preferred embodiment, the non-aqueous organic solvent comprises a mixture of cyclic carbonates and chain carbonates.

[0103] In some embodiments, the electrolyte salt is selected from at least one of lithium salts, sodium salts, potassium salts, magnesium salts, zinc salts, and aluminum salts. In a preferred embodiment, the electrolyte salt is selected from lithium salts or sodium salts.

[0104] In non-aqueous electrolytes, alkali metal ions formed by the dissociation of electrolyte salts undergo intercalation and deintercalation between the positive and negative electrodes to complete charge-discharge cycles. The concentration of the electrolyte salt directly affects the transfer rate of alkali metal ions, which in turn affects the potential change at the negative electrode. During fast charging, it is necessary to maximize the movement speed of alkali metal ions to prevent the negative electrode potential from dropping too quickly, which could lead to the formation of lithium dendrites and pose a safety hazard to the battery. This also helps prevent the battery's cycle capacity from decaying too rapidly. If the electrolyte salt content is too low, the intercalation and deintercalation efficiency of alkali metal ions between the positive and negative electrodes will be reduced, failing to meet the requirements of fast charging. Conversely, if the electrolyte salt content is too high, the viscosity of the non-aqueous electrolyte will increase, which is also detrimental to improving the intercalation and deintercalation efficiency of alkali metal ions and increases the battery's internal resistance.

[0105] In some embodiments, the electrolyte salt is selected from lithium salts, including LiPF6, LiBOB, LiPO2F2, LiBF4, LiSbF6, LiAsF6, LiN(SO2F)2, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiClO4, LiAlCl4, LiCF3SO3, LiSO3F, and Li2B. 10 Cl 10At least one of lithium chloroborane, lithium trioxazophosphate, lithium lower aliphatic carboxylic acid having four or fewer carbon atoms, or lithium tetraphenylborate.

[0106] In some embodiments, the concentration of the lithium salt in the non-aqueous electrolyte is 0.1 mol / L to 4 mol / L. In a preferred embodiment, the concentration of the lithium salt in the non-aqueous electrolyte is 0.5 mol / L to 2.5 mol / L. Specifically, in the non-aqueous electrolyte, the concentration of the lithium salt can be 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L, 0.7 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L, 1.0 mol / L, 1.1 mol / L, 1.15 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.45 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L, or 2.5 mol / L.

[0107] In a specific embodiment, the concentration of the sodium salt is 0.1 mol / L to 2 mol / L. In a preferred embodiment, the concentration of the sodium salt is 0.4 mol / L to 1.5 mol / L. Specifically, the concentration of the sodium salt can be 0.1 mol / L, 0.4 mol / L, 0.5 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, or 2 mol / L.

[0108] In a specific embodiment, the sodium salt is selected from at least one of sodium perchlorate (NaClO4), sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium bis(fluorosulfonyl)imide (NaFSI), sodium trifluoromethanesulfonate (NaOTf), and sodium bis(trifluoromethanesulfonyl)imide (NaTFSI).

[0109] In other embodiments, if the non-aqueous electrolyte is used in a sodium-ion battery, the electrolyte may also be a corresponding sodium salt.

[0110] Fourthly, this application provides a secondary battery, including the non-aqueous electrolyte as described above. In some embodiments, the secondary battery is a lithium-ion battery.

[0111] In some embodiments, the positive electrode includes a positive electrode material layer, and the positive electrode material layer includes a positive electrode active material. The type and content of the positive electrode active material are not particularly limited and can be selected according to actual needs. It can be any positive electrode active material or conversion type positive electrode material that can reversibly insert / deintercalate metal ions (lithium ions, sodium ions, potassium ions, magnesium ions, zinc ions, aluminum ions, etc.).

[0112] In a preferred embodiment, the secondary battery is a lithium-ion battery, and the positive electrode active material is selected from LiFe. 1-x’ M' x’ PO4, LiMn 2-y’ M y’ O4 and LiNi x Co y Mn z M 1-x-y-z At least one of O2, wherein M' is selected from at least one of Mn, Mg, Co, Ni, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, Zr, W, V or Ti, and M is selected from at least one of Fe, Co, Ni, Mn, Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, Zr, W, V or Ti, and 0≤x'<1, 0≤y'≤1, 0≤y≤1, 0≤x≤1, 0≤z≤1, x+y+z≤1.

[0113] The positive electrode active material may also be selected from at least one of sulfides, selenides, and halides.

[0114] More preferably, the positive electrode active material can be selected from LiCoO2, LiFePO4, or LiFe 0.8 Mn 0.2 PO4, LiMn2O4, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.5 Co 0.2 Mn 0.2 Al 0.1 O2, LiNi 0.5 Co 0.2 Al 0.3 At least one of O2.

[0115] In a preferred embodiment, the secondary battery is a sodium-ion battery, and its positive electrode active material includes, but is not limited to, at least one of transition metal oxides, Prussian materials, phosphates, sulfates, and titanate materials. Among them, the chemical formula of the transition metal oxide can be Na z M x O y , M can be selected from at least one of Cr, Fe, Co, Ni, Cu, Mn, Sn, Mo, Sb, V. More preferably, the transition metal oxide is NaNi m Fe n Mn p O2 (m + n + p = 1, 0 ≤ m ≤ 1, 0 ≤ n ≤ 1, 0 ≤ p ≤ 1) or NaNi m Co n Mn p O2 (m + n + p = 1, 0 ≤ m ≤ 1, 0 ≤ n ≤ 1, 0 ≤ p ≤ 1); the molecular formula of the Prussian material is Na x M[M′(CN)6] y ·zH2O, where M is a transition metal, M′ is a transition metal, 0 < x ≤ 2, 0.8 ≤ y < 1, 0 < z ≤ 20. More preferably, the Prussian material is Na x Mn[Fe(CN)6] y ·nH2O (0 < x ≤ 2, 0 < y ≤ 1, 0 < z ≤ 10) or Na x Fe[Fe(CN)6] y ·nH2O (0 < x ≤ 2, 0 < y ≤ 1, 0 < z ≤ 10); the chemical formula of the phosphate is Na3(MO 1-x PO4)2F 1+2x , 0 ≤ x ≤ 1, M is selected from at least one of Al, V, Ge, Fe, Ga. More preferably, the phosphate is Na3(VPO4)2F3 or Na3(VOPO4)2F; the chemical formula of the phosphate is Na2MPO4F, M is selected from at least one of Fe, Mn. More preferably, the phosphate is Na2FePO4F or Na2MnPO4F; the titanate material can be selected from at least one of Na2Ti3O7, Na2Ti6O 13 , Na4Ti5O 12 , Li4Ti5O 12 , NaTi2(PO4)3; the chemical formula of the sulfate is Na2M(SO4)2·2H2O, M can be selected from at least one of Cr, Fe, Co, Ni, Cu, Mn, Sn, Mo, Sb, V.

[0116] In some embodiments, the positive electrode material layer further includes a positive electrode binder and a positive electrode conductive agent, and the positive electrode active material, the positive electrode binder and the positive electrode conductive agent are blended to obtain the positive electrode material layer.

[0117] The positive electrode binder includes at least one of the following: polyvinylidene fluoride (PVDF), copolymers of PVDF, polytetrafluoroethylene (PTFE), copolymers of PVDF-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of PVDF-tetrafluoroethylene, copolymers of PVDF-trifluoroethylene, copolymers of PVDF-trichloroethylene, copolymers of PVDF-fluorinated vinylidene, copolymers of PVDF-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene; acrylic resins; and styrene-butadiene rubber.

[0118] The positive electrode conductive agent includes at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fiber, carbon nanotubes, graphene, or reduced graphene oxide.

[0119] In some embodiments, the positive current collector comprises a metallic material capable of conducting electrons. Preferably, the positive current collector comprises at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the positive current collector is selected from aluminum foil.

[0120] In some embodiments, the negative electrode includes a negative electrode material layer, the negative electrode material layer includes a negative electrode active material, the secondary battery is a lithium-ion battery, and the negative electrode active material includes at least one of carbon-based negative electrode, silicon-based negative electrode, tin-based negative electrode, and lithium negative electrode. The carbon-based negative electrode may include graphite, hard carbon, soft carbon, graphene, mesophase carbon microspheres, etc.; the silicon-based negative electrode may include silicon materials, silicon oxides, silicon-carbon composite materials, and silicon alloy materials, etc.; the tin-based negative electrode may include tin, tin-carbon, tin oxide, and tin metal compounds; the lithium negative electrode may include metallic lithium or lithium alloys. Specifically, the lithium alloy may be at least one of lithium-silicon alloy, lithium-sodium alloy, lithium-potassium alloy, lithium-aluminum alloy, lithium-tin alloy, and lithium-indium alloy.

[0121] In a more preferred embodiment, the negative electrode active material includes at least one of graphite, hard carbon, soft carbon, graphene, and silicon-carbon composite materials.

[0122] In some embodiments, the silicon material is one or more of silicon nanoparticles, silicon nanowires, silicon nanotubes, silicon thin films, 3D porous silicon, and hollow porous silicon.

[0123] In a preferred embodiment, the secondary battery is a sodium-ion battery, and its negative electrode active material includes at least one of metallic sodium, graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals that can form alloys with sodium. The alloy material may also be selected from at least one of Si, Ge, Sn, Pb, and Sb combined with C; the graphite may be selected from at least one of artificial graphite, natural graphite, and modified graphite; the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys; and the tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys.

[0124] In some embodiments, the negative electrode further includes a negative electrode current collector, and the negative electrode material layer covers the surface of the negative electrode current collector. The negative electrode current collector includes a metallic material capable of conducting electrons. Preferably, the negative electrode current collector includes at least one of Al, Ni, tin, copper, and stainless steel. In a more preferred embodiment, the negative electrode current collector is selected from copper foil.

[0125] In some embodiments, the negative electrode material layer further includes a negative electrode binder and a negative electrode conductive agent, and the negative electrode active material, the negative electrode binder and the negative electrode conductive agent are blended to obtain the negative electrode material layer.

[0126] The negative electrode binder includes at least one of the following: polyvinylidene fluoride (PVDF), copolymers of PVDF, polytetrafluoroethylene (PTFE), copolymers of PVDF-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, copolymers of tetrafluoroethylene-perfluoroalkyl vinyl ethers, copolymers of ethylene-tetrafluoroethylene, copolymers of PVDF-tetrafluoroethylene, copolymers of PVDF-trifluoroethylene, copolymers of PVDF-trichloroethylene, copolymers of PVDF-fluorinated vinylidene, copolymers of PVDF-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, polyethylene, and polypropylene; acrylic resins; and styrene-butadiene rubber.

[0127] The negative electrode conductive agent includes at least one of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fiber, carbon nanotubes, graphene, or reduced graphene oxide.

[0128] In some embodiments, the secondary battery further includes a separator located between the positive electrode and the negative electrode.

[0129] The diaphragm can be a conventional diaphragm, such as a ceramic diaphragm, a polymer diaphragm, a non-woven fabric, or an inorganic-organic composite diaphragm, including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP / PE, double-layer PP / PP, and triple-layer PP / PE / PP diaphragms.

[0130] The present invention will be further illustrated by the following examples.

[0131] Preparation Example 1 The structure of 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexaol is structural formula 2.

[0132] Preparation of cyclic carbonate-sulfate compound A: S1: Methanol and dimethyl carbonate were added to 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexane, mixed thoroughly, and heated to 60℃ for 10 h to obtain the carbonate polyol intermediate shown in structural formula 3. The molar ratio of 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexane to methanol was 1:10; the molar ratio of 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexane to dimethyl carbonate was 1:12.

[0133] S2: The carbonate polyol intermediate (structure 3) prepared in step S1, sulfonyl chloride, and other components are mixed evenly, cooled to -20℃, and triethylamine is slowly added to react for 4 hours to obtain crude cyclic carbonate-sulfate ester. The molar ratio of the carbonate polyol intermediate to sulfonyl chloride is 1:2; the mass ratio of the carbonate polyol intermediate to triethylamine is 1:2.1.

[0134] S3: Isopropanol and methanol were mixed at a mass ratio of 2:7 to obtain an alcohol solution. The crude cyclic carbonate-sulfate obtained in step S2 was recrystallized using the alcohol solution to obtain the target product, cyclic carbonate-sulfate compound A. The target product was subjected to 1H NMR spectroscopy, and the test results are as follows. Figure 1 As shown, the target product was subjected to carbon NMR spectroscopy, and the test results are as follows. Figure 2 As shown, it is confirmed that the cyclic carbonate-sulfate compound A contains the compound shown in structural formula 1.

[0135] Simultaneously, the obtained cyclic carbonate-sulfate compound A was dissolved in acetonitrile and injected, and chromatographic analysis was performed using high-performance liquid chromatography (HPLC) (instrument: Agilent 1200 series HPLC system, Waters ultra-high performance chromatographic system; column temperature: 25℃; flow rate: 1.0 mL / min). The results showed that the content of the single configuration of the compound represented by chemical formula 1 in cyclic carbonate-sulfate compound A was 99%. The proportion of stereoisomer impurities in the compound represented by chemical formula 1 was 1%.

[0136] In cyclic carbonate-sulfate compound A, the mass content of the compound shown in formula 1 is 99%, and the content of organic impurities is 1%. The chlorine content of the compound was determined to be 100 ppm by turbidimetric assay.

[0137] Furthermore, the specific rotation of cyclic carbonate-sulfate compound 1 was tested according to the following method: Weigh 5g of cyclic carbonate-sulfate compound A and completely dissolve it in acetone (acetone purity >99%, water content <1000ppm) to prepare a solution with a concentration of 0.151g / mL. Test the specific rotation according to GB / T 613-2007 General Test Method for Determination of Specific Rotation of Chemical Reagents. Test conditions: wavelength 589nm, temperature 25°C, solvent acetone, test tube length 100mm, concentration 0.151g / mL. The specific rotation was measured as follows: α ]=-6.228 , abbreviated as specific rotation [ α = -6.228.

[0138] In summary, the obtained cyclic carbonate-sulfate compound A contains 99% by mass of the compound represented by Formula 1 (in Formula 1, the compound represented by Structural Formula 1 accounts for 99% of the total mass of the compound represented by Formula 1, and the stereoisomer impurities account for 1% of the total mass of the compound represented by Formula 1), and 1% by mass of organic impurities. The total chlorine content of the compound was determined to be 100 ppm by turbidimetric assay.

[0139] Furthermore, cyclic carbonate-sulfate compounds of different purities can be obtained by recrystallization (natural crystallization in a mixed solvent of isopropanol and methanol) or high performance liquid chromatography to prepare a gradient elution, collect and concentrate in batches, and further purify and separate them. The specific rotation of the cyclic carbonate-sulfate compounds is affected by the proportion of structural formula 1, as shown in Table 1.

[0140] Test conditions: wavelength 589nm, temperature 25 degrees Celsius, solvent acetone, test tube length 100mm, concentration of cyclic carbonate-sulfate compound 1 0.151g / mL.

[0141] Table 1 Preparation Example 2 Preparation of cyclic carbonate-sulfate compound B The procedure is largely the same as in Preparation Example 1, except that the hexahydrol is a mixture of 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexahydrol (same structure as in Preparation Example 1) and D-mannitol, with a mass ratio of 40:60 between the 2R,3R,4S,5S-hexane-1,2,3,4,5,6-hexahydrol and the mannitol. The rest is the same as in Preparation Example 1.

[0142] Preparation Example 2 yielded a cyclic carbonate-sulfate compound B, in which the mass content of the compound represented by Formula 1 was 99% (the mass ratio of the compound represented by Formula 1 to the compound represented by Formula 1 was 60%, and the mass ratio of stereoisomer impurities to the compound represented by Formula 1 was 40%). The mass content of organic impurities was 1%. The chlorine content of the compound was determined to be 98 ppm by turbidimetric assay.

[0143] Weigh 5g of cyclic carbonate-sulfate compound B and completely dissolve it in acetone (acetone purity >99%, water content <1000ppm) to prepare a solution. The concentration of cyclic carbonate-sulfate compound B is 0.151g / mL. Test according to GB / T 613-2007 General Test Method for Determination of Specific Rotation of Chemical Reagents: wavelength 589nm, temperature 25°C, solvent acetone, test tube length 100mm, concentration 0.151g / mL. The specific rotation was measured as follows: α ]=-10.258 , abbreviated as specific rotation [ α = -10.258.

[0144] Preparation Example 3 Preparation of cyclic carbonate-sulfate compound C: (1) Place 20.0 g of D-mannitol and 40.0 mg of potassium carbonate (K2CO3) in a 500 mL three-necked round-bottom flask, then add 60 mL of methanol and heat to 60 °C. While stirring, add 138.6 mL of dimethyl carbonate (DMC) dropwise over 30 minutes. After the DMC is completely added, heat to 66 °C and reflux with stirring for 3 hours to produce a crude carbonate polyol. Then, concentrate the crude carbonate polyol under reduced pressure and add 40 mL of methanol to dissolve it completely. Recrystallize by slowly adding 200 mL of ethyl acetate (EA). Filter the resulting crystals under reduced pressure to obtain 14.6 g of intermediate 1.

[0145] (2) Place 10.0 g of intermediate product 1 and 12 g of thionyl chloride into a 250 mL three-necked round-bottom flask, then add 100 g of dichloromethane and heat to 60 °C. Reflux for 6 hours. Aerate the reaction, absorbing the tail gas until no more gas is produced. Afterward, concentrate the solid under reduced pressure, add 20 mL of diethyl carbonate and slurry, maintaining the temperature at 5 °C and stirring for 0.5 hours. Filter under reduced pressure, concentrate, and dry to obtain 11.5 g of intermediate product 2. (3) Place 10.0 g of intermediate product 2 and 100 g of acetonitrile into a 250 mL three-necked round-bottom flask, and control the temperature at 10-15 degrees Celsius. Add 10 g of 40% hydrogen peroxide dropwise, controlling the temperature to be below 35 degrees Celsius during the addition process, and stir the reaction for 6 hours. Then filter under reduced pressure, concentrate and dry to obtain 8.23 ​​g of cyclic carbonate-sulfate compound C.

[0146] Testing revealed that the compound C, a cyclic carbonate-sulfate compound, contained 99.7% of the compound represented by Formula 1 (the proportion of Formula 1 to the total compound of Formula 1 was <1%, and the mass ratio of stereoisomer impurities to the compound represented by Formula 1 was 99%). The mass content of organic impurities was 0.3%. Turbidimetric analysis showed that the chlorine content of the compound was 100 ppm. Specific rotation was measured under the following conditions: wavelength 589 nm, temperature 25°C, solvent acetone, test tube length 100 mm, concentration 0.151 g / mL. The specific rotation was -12.841. .

[0147] Preparation Example 4 Preparation of cyclic carbonate-sulfate compound D The procedure largely follows that of Preparation Example 3, except that D-mannitol is replaced with sorbitol. A cyclic carbonate-sulfate compound D is thus prepared.

[0148] In the obtained cyclic carbonate-sulfate compound D, the mass content of the compound represented by Formula 1 is 99% (in Formula 1, the mass content of the compound represented by Structural Formula 1 is less than 1%, and the mass ratio of stereoisomer impurities to the compound represented by Formula 1 is 99%), and the mass content of organic impurities is 1%. The chlorine content of the compound was determined to be 92 ppm by turbidimetric assay.

[0149] Weigh 5g of cyclic carbonate-sulfate compound D, completely dissolve it in acetone (acetone purity >99%, water content <1000ppm) to prepare a solution, and the concentration of cyclic carbonate-sulfate compound D is 0.151g / mL. Test according to GB / T 613-2007 General Test Method for Determination of Specific Rotation of Chemical Reagents, test conditions: wavelength 589nm, temperature 25°C, solvent acetone, test tube length 100mm, concentration 0.151g / mL. The specific rotation was measured as follows: α ]=9.682 , abbreviated as specific rotation [ α =9.682.

[0150] Examples 1-10, Comparative Examples 1-14 1) Preparation of non-aqueous electrolyte Ethylene carbonate (EC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC) were mixed in a mass ratio of EC:DEC:EMC = 1.1:1:1. Then, lithium hexafluorophosphate (LiPF6) was added to a molar concentration of 1.1 mol / L. Auxiliary additives and the cyclic carbonate-sulfate compound prepared above were then added and dissolved in the above non-aqueous organic solvent to obtain a non-aqueous electrolyte. The selection of the cyclic carbonate-sulfate compound and its content in the non-aqueous electrolyte, as well as the selection of the auxiliary additives and their content in the non-aqueous electrolyte in each example and comparative example, are shown in Table 2. The content is calculated as a percentage of the total mass of the non-aqueous electrolyte.

[0151] 2) Preparation of lithium-ion batteries Preparation of S11 cathode: Lithium nickel cobalt manganese oxide (LiNiO) was mixed with the cathode active material in a mass ratio of 93:3:4. 0.5 Co 0.2 Mn 0.3 O2, conductive carbon black Super-P, and the binder polyvinylidene fluoride (PVDF) were then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry with a viscosity of approximately 8000 mPa·s. The slurry was uniformly coated on opposite surfaces of an 18 μm thick aluminum foil, and after drying, calendering, and vacuum drying, aluminum leads were welded on using an ultrasonic welder to obtain a positive electrode sheet with a thickness of 120 μm.

[0152] Preparation of S12 negative electrode sheet: A mixture of artificial graphite (negative electrode active material), Super-P conductive carbon black, styrene-butadiene rubber (SBR) binder, and carboxymethyl cellulose (CMC) was prepared in a mass ratio of 94:1:3:2. This mixture was then dispersed in deionized water to obtain a negative electrode slurry with a viscosity of approximately 4000 mPa·s. The slurry was coated onto the opposite surfaces of an 8 μm thick copper foil. After drying, rolling, and vacuum drying, nickel leads were welded onto the foil using an ultrasonic welder to obtain a negative electrode plate with a thickness of 120 μm.

[0153] Preparation of S13 battery cell: A three-layer PP / PE / PP separator with a thickness of 20μm is placed between the positive and negative electrodes. Then, the sandwich structure composed of the positive electrode, negative electrode and separator is wound up. The wound body is then flattened and placed in an aluminum foil packaging bag. It is then vacuum baked at 75℃ for 48h to obtain the battery cell to be injected with electrolyte.

[0154] Electrolyte injection and formation of S14 cells: In a glove box with the dew point controlled below -40°C, the electrolyte prepared in this embodiment is injected into the cell, vacuum sealed, and left to stand for 24 hours.

[0155] The initial formation was then performed as follows: constant current charging at 0.05C for 180 minutes, constant current charging at 0.2C to 3.95V, followed by a second vacuum sealing. Then, it was further charged at a constant current of 0.2C to 4.2V, left to stand at room temperature for 24 hours, and finally discharged at a constant current of 0.2C to 3.0V to obtain a LiNi alloy. 0.5 Co 0.2 Mn 0.3 O2 / artificial graphite lithium-ion battery.

[0156] Battery performance test: The following tests were performed on the batteries obtained in Examples 1-10 and Comparative Examples 1-14. 1. Discharge capacity ratio test: Five lithium-ion batteries from each group prepared using the electrolytes of all comparative examples and embodiments were taken and charged at a constant current rate of 0.5C to 4.35V at 25°C. Then, they were charged at a constant voltage rate of 4.35V until the current dropped to 0.05C and left to stand for 5 minutes. The lithium-ion batteries were then discharged to 3.0V at different rates of 0.3C, 1C, and 2.0C. After each discharge, they were left to stand for 5 minutes and the discharge capacity of the lithium-ion batteries was recorded. The discharge capacity at a discharge rate of 0.3C was used as the benchmark, and the discharge capacity ratio of the lithium-ion batteries at different discharge rates was calculated using the following formula.

[0157] The rate discharge capacity ratio (%) of a lithium-ion battery = (discharge capacity at the corresponding rate / discharge capacity at 0.3C rate) * 100%.

[0158] 2. Thermal Shock Test: After formation, the battery is charged at a constant current of 0.5C to 4.5V, then charged at a constant voltage until the current drops to 0.03C. It is then discharged at a constant current of 0.5C to 3.0V. This procedure is repeated 10 times at room temperature (25℃). The battery discharge capacity is calculated. If the discharge capacity deviation is within ±10mAh / g, the battery is charged at a constant current of 0.5C to 4.35V, then charged at a constant voltage until the current drops to 0.03C. This is considered the battery's fully charged state. The fully charged battery is placed in a GX-3020-BL40 thermal shock test chamber. The chamber operates according to the set program of "heating from 25℃ to 130℃ at a rate of 5℃ / min and holding for 30 minutes." Simultaneously, the temperature and voltage channels on the "data acquisition instrument" panel begin recording real-time data. During the test, if the battery surface temperature detected by the data acquisition instrument does not exceed 200℃ and the voltage drop does not exceed 0.3V, and the battery does not explode or catch fire, then the hot box passes OK; otherwise, it is NG. Record the highest temperature value in the battery table and take the average value. Each group has 20 batteries.

[0159] The test results are recorded in Table 2: Table 2 As shown in Table 2, the cyclic carbonate-sulfate compound A prepared using the hexaol of structural formula 2 described in this application, the cyclic carbonate-sulfate compound C prepared using D-mannitol, and the cyclic carbonate-sulfate compound D prepared using sorbitol were used as electrolyte additives. The resulting batteries, compared with Examples 4 and Comparative Examples 6 and 8, Examples 6 and Comparative Examples 9 and 13, and Examples 7 and Comparative Examples 10 and 14, demonstrate that the cyclic carbonate-sulfate compound prepared using the hexaol of structural formula 2 described in this application includes chemical formula 1, and the mass content of the compound shown in structural formula 1 in chemical formula 1 is ≥99%. The specific rotation of the cyclic carbonate-sulfate compound […]. α The value is -6.228. The improved spatial structural symmetry significantly enhances the rate discharge capacity retention and high-temperature performance of lithium-ion batteries. This is primarily due to the structure of the compound shown in Formula 1, where all rings are aligned in the same plane. Furthermore, the packing of the -SO2- and -CO- groups with lithium ions is appropriately balanced, avoiding either loose or tight packing. Simultaneously, it weakens the solvation of lithium ions and electrolytes, inhibits co-intercalation of the solvent and electrolyte decomposition, and prevents the shedding of the negative electrode material layer. This results in a stable SEI (solid electrolyte membrane) structure at the negative electrode interface, good metal ion migration rate, and improved high-rate discharge and high-temperature performance of the battery.

[0160] Compared with Comparative Example 1, Example 4, lacking cyclic carbonate-sulfate compounds in the electrolyte, showed poor rate discharge capacity retention and a low success rate in hot-box testing. Compared with Comparative Examples 2-5, Example 4, compared to traditional vinylene carbonate (VC), vinyl sulfate (DTD), and 1,3-propanesulfonate lactone (PS), utilizes the cyclic carbonate-sulfate compounds provided in this application as additives. Furthermore, these cyclic carbonate-sulfate compounds contain the compound shown in Formula 1, with a content ≥99% and a concentration of ≥99 wt% of the compound shown in Formula 1. This significantly improves the rate discharge capacity retention and high-temperature performance of lithium-ion batteries. A comparison of Examples 1-9 shows that, with the increase of the content of cyclic carbonate-sulfate compounds in the electrolyte, the high-rate charge-discharge capacity retention of the battery first increases and then decreases, while the number of NG batteries in the hot box test first decreases and then increases. This indicates that both excessive and insufficient addition will improve the high-temperature performance and high-rate charge-discharge capacity retention of lithium-ion batteries, especially when the content of cyclic carbonate-sulfate compounds in the electrolyte is in the range of 0.1% to 5%, the hot box performance is better. More preferably, when the content of cyclic carbonate-sulfate compounds in the electrolyte is in the range of 0.5% to 5%, the high-rate charge-discharge capacity retention is even higher.

[0161] A comparison of Examples 4 and 10 shows that the addition of 1,3-propanesulfonate lactone (PS) to the electrolyte can have a synergistic effect with cyclic carbonate-sulfate compounds, further improving the battery's high-temperature performance and high-rate discharge capacity retention.

[0162] Cyclic carbonate-sulfate compound B was prepared using a mixture of hexahydrol and D-mannitol (shown in Formula 2) at a mass ratio of 40:60. The resulting battery was compared with Example 4 and Comparative Example 7, Example 6 and Comparative Example 11, and Example 7 and Comparative Example 12. It was found that when the mass content of the compound shown in Formula 1 in Chemical Formula 1 is less than 99%, the rate discharge capacity retention of the battery decreases with increasing discharge rate. This suggests that a decrease in the content of structures with ring planes in the same direction reduces the number of -SO2- and -CO- groups that can compete with metal ions, weakening the solvation effect of metal ions (such as lithium ions) and ECs. Consequently, the battery cannot effectively compete with ECs and metal ions for solvation, resulting in reduced high-rate charge / discharge capacity performance. This indicates that when the mass content of the compound shown in Formula 1 in Chemical Formula 1 is ≥99%, the battery has a high rate discharge capacity retention and good high-temperature performance.

[0163] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cyclic carbonate-sulfate compound, characterized in that, The cyclic carbonate-sulfate compound includes the compound shown in Formula 1, and the compound shown in Formula 1 includes 99 wt% or more of the compound shown in Formula 1. The specific rotation of the cyclic carbonate-sulfate compound [ α The value is -6.

228. above.

2. The cyclic carbonate-sulfate compound according to claim 1, characterized in that, In the cyclic carbonate-sulfate compound, the content of the compound represented by chemical formula 1 is ≥99 wt%.

3. The cyclic carbonate-sulfate compound according to claim 1, characterized in that, The compound represented by Chemical Formula 1 also includes stereoisomer impurities, and the content of the stereoisomer impurities in the compound represented by Chemical Formula 1 is ≤1 wt%. And / or, the chlorine content in the cyclic carbonate-sulfate compound is ≤100ppm.

4. The cyclic carbonate-sulfate compound according to claim 1, characterized in that, The cyclic carbonate-sulfate compound also includes organic impurities, the content of which is ≤1 wt%. The organic impurities include one or more of the following compounds: 。 5. The cyclic carbonate-sulfate compound according to claim 1, characterized in that, The specific rotation [ α The test conditions were: wavelength 589 nm, temperature 25 degrees Celsius, solvent acetone, test tube length 100 mm, and concentration of cyclic carbonate-sulfate compound 0.151 g / mL.

6. A method for preparing the cyclic carbonate-sulfate compound according to any one of claims 1-5, characterized in that, Includes the following steps: A carbonate polyol intermediate is obtained by mixing and reacting hexahydrol, low alcohol, and carbonate compounds. The carbonate polyol intermediate, sulfonyl compound, and basic compound are then reacted to obtain crude cyclic carbonate-sulfate. The crude cyclic carbonate-sulfate is then post-processed to obtain the cyclic carbonate-sulfate compound.

7. The method for preparing the cyclic carbonate-sulfate compound according to claim 6, characterized in that, The hexahydrol includes the compound shown in structural formula 2: Structural Formula 2; The low alcohol comprises at least one of a monohydric alcohol and a dihydric alcohol, wherein the monohydric alcohol comprises C n H 2n+1 OH, n is 1~4; the diol includes C m H 2m+2 O2, m is 1~4; The sulfonyl compounds include sulfonyl chlorides; The carbonate compounds include one or more of cyclic carbonates and chain carbonates; The cyclic carbonates include ethylene carbonate, and the chain carbonates include one or more of ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, and diphenyl carbonate. The alkaline compound includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate, sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert-butoxide, triethylamine, and pyridine.

8. The method for preparing the cyclic carbonate-sulfate compound according to claim 6, characterized in that, The molar ratio of the hexahydrol to the lower alcohol is 1:(5~15). The molar ratio of the hexahydrol to the carbonate compound is 1:(10~15). The molar ratio of the carbonate polyol intermediate to the sulfonyl compound is 1:(1.8~3). The mass ratio of the carbonate polyol intermediate to the basic compound is 1:(2~3.5).

9. The method for preparing the cyclic carbonate-sulfate compound according to claim 6, characterized in that, The reaction temperature of the mixture is 60~120℃, and the reaction time of the mixture is 2~12h; The reaction temperature in the step of reacting the carbonate polyol intermediate, sulfonyl compound and basic compound to obtain crude cyclic carbonate-sulfate is -78~10℃ and the reaction time is 1~4h. And / or, the post-processing includes the following steps: recrystallizing the crude cyclic carbonate-sulfate product using an alcohol solution to obtain the cyclic carbonate-sulfate compound.

10. A non-aqueous electrolyte, characterized in that, It includes non-aqueous organic solvents, electrolyte salts, and additives, wherein the additives include cyclic carbonate-sulfate compounds as described in any one of claims 1 to 9; And / or, based on the total mass of the non-aqueous electrolyte, the mass percentage of the cyclic carbonate-sulfate compound is 0.05% to 10%.

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