Electrolyte and lithium ion battery containing same
By using p-sulfonylmethyl isocyanate compounds as additives in lithium-ion batteries to form a stable SEI film, the limitations of electrolyte on cycle performance are solved, achieving high-efficiency cycle performance and long lifespan of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-05
- Publication Date
- 2026-05-12
AI Technical Summary
The cycle performance of existing lithium-ion batteries is limited, especially due to the influence of the electrolyte on the SEI film, resulting in insufficient cycle stability.
Using p-sulfonylmethyl isocyanate compounds as electrolyte additives forms a stable SEI film, improves the cycle stability of the battery, inhibits the hydrolysis reaction of LiPF6, and reduces the generation of harmful product HF and the dissolution of cathode transition metals.
It significantly improves the cycle stability and lifespan of lithium-ion batteries, especially under normal and high temperature conditions, enhancing battery capacity retention and cycle performance.
Smart Images
Figure CN122025795A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to an electrolyte and a lithium-ion battery containing the electrolyte. Background Technology
[0002] Lithium-ion batteries possess advantages such as high voltage, no memory effect, high capacity, and long lifespan, making them an ideal chemical power source. They are widely used in consumer electronics, power batteries, and energy storage. With the booming new energy vehicle market, the power battery market is also experiencing a golden age, and cycle performance, as one of the key performance indicators of battery cells, is undoubtedly receiving much attention.
[0003] Many factors influence the cycle life of lithium-ion batteries. The main materials of the positive and negative electrodes, conductive agents, and binders all affect the cycle performance of the battery to a certain extent. As an important component of lithium-ion batteries, the electrolyte plays a role in ion transport within the battery. Different electrolyte additives also have a decisive influence on the composition and performance of the SEI film, thereby affecting the cycle stability of the battery, that is, the cycle performance of the cell. Therefore, a suitable lithium-ion battery electrolyte also affects the cycle performance of the battery. Summary of the Invention
[0004] The purpose of this invention is to provide an electrolyte and a lithium-ion battery containing the electrolyte. The electrolyte of this invention can form a stable SEI film on the electrode surface, improving the cycle stability of the battery and thus enabling the battery to achieve excellent cycle performance.
[0005] This invention provides an electrolyte comprising an electrolyte lithium salt, an organic solvent, auxiliary additives, and a p-sulfonylmethyl isocyanate compound;
[0006] The structural formula of the p-sulfonylmethyl isocyanate compound is shown in Formula I:
[0007] In Formula I, R is selected from hydrogen atoms, halogens, and C. 1-20 Alkyl, halogen-substituted C 1-20 Alkyl, C 3-20 cycloalkyl, C 3-10 Epoxyalkyl, C 2-20 alkenyl, C 2-20 alkynyl group, C 3-20 Cycloalkenyl, C 6-26 Aryl and C 6-26 At least one of the heteroaryl groups.
[0008] The electrolyte described above is made from components comprising the following components in weight percentages: Electrolyte lithium salt 10~14%; Auxiliary additives 1~5%; The p-sulfonyl methyl isocyanate compound is 1-5%; The remainder is the organic solvent.
[0009] The electrolyte described above is made from components comprising the following components in weight percentages: Electrolyte lithium salt 10~14%; Auxiliary additives 1~5%; The p-sulfonyl methyl isocyanate compound 3%; The remainder is the organic solvent.
[0010] In this invention, the electrolyte is made from the following components in weight percentages: Electrolyte lithium salt 14%; 1% auxiliary additives; The p-sulfonyl methyl isocyanate compound 3%; The remainder is the organic solvent.
[0011] In the electrolyte described above, in Formula I, R is selected from hydrogen atoms, halogens, and C. 1-10 Alkyl, halogen-substituted C 1-10 Alkyl, C 3-20 cycloalkyl, C 3-5 Epoxyalkyl, C 2-10 alkenyl, C 2-10 alkynyl group, C 3-10 Cycloalkenyl, C 6-16 Aryl and C 6-16 At least one of the heteroaryl groups.
[0012] In the above-mentioned electrolyte, the p-sulfonylmethyl isocyanate compound is selected from at least one of the following structural formulas: .
[0013] In the above-mentioned electrolyte, the electrolyte lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluorooxalateborate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide.
[0014] In the electrolyte described above, the organic solvent is selected from at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propyl methyl carbonate, ethylene carbonate, and propylene carbonate.
[0015] In the electrolyte described above, the auxiliary additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, vinyl sulfite, 1,3-propane sulpholactone, 1,4-butane sulpholactone, propylene sulfate, and ethylene ethylene carbonate.
[0016] The present invention also provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte as described in any one of claims 1-8.
[0017] In the aforementioned lithium-ion battery, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer composited on the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, which is selected from at least one of lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt manganese oxide, and lithium iron phosphate. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer composited on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, which is at least one of carbon-containing materials, titanium oxide, silicon, lithium, and lithium alloys. The diaphragm is made of at least one of polyethylene, polypropylene and polyvinylidene fluoride.
[0018] The present invention has the following beneficial effects: This invention utilizes p-sulfonylmethyl isocyanates as electrolyte additives. The sulfone group in their structure contributes high reducing activity, while the phenyl group contributes high oxidizing activity. Experimental results show that electrolytes containing p-sulfonylmethyl isocyanates can simultaneously generate effective cathode electrolyte interface layers and solid electrolyte interface layers on the positive and negative electrode surfaces, significantly improving battery cycle stability. Furthermore, experiments revealed that electrolytes containing p-sulfonylmethyl isocyanates can inhibit the hydrolysis of LiPF6, thereby hindering the generation of harmful HF products and the dissolution of cathode transition metals, thus improving battery cycle life. Detailed Implementation
[0019] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.
[0020] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.
[0021] The technical solution of the present invention will now be described in detail through specific embodiments.
[0022] The electrolyte provided by this invention is made from components comprising the following components in weight percentages: The electrolyte lithium salt is 10-14%; auxiliary additives are 1-5%; the p-sulfonylmethyl isocyanate compound is 1-5%; and the balance is the organic solvent.
[0023] sulfonylmethyl isocyanates are selected from at least one of the following structural formulas: .
[0024] Example 1 An electrolyte for improving the cycle performance of lithium-ion batteries comprises, by mass percentage: 14% lithium hexafluorophosphate, 1% ethylene sulfite, 1% p-sulfonylmethyl isocyanate, and the balance being an organic solvent, wherein the organic solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a mass ratio of EC:EMC:DMC = 2:5:3.
[0025] The structural formula of compound 1, a sulfonylmethyl isocyanate, is as follows:
[0026] The synthetic route for sulfonylmethyl isocyanate compound 1 is as follows:
[0027] The preparation method of the above electrolyte is as follows: In an argon glove box with moisture content controlled to ≤10ppm, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed evenly at a mass ratio of EC:EMC:DMC = 2:5:3 to obtain an organic solvent. Lithium hexafluorophosphate was then slowly added to the organic solvent. After the lithium hexafluorophosphate was completely dissolved, p-sulfonylmethyl isocyanate and vinyl sulfite were added and stirred evenly to obtain an electrolyte.
[0028] Example 2 An electrolyte for improving the cycle performance of lithium-ion batteries comprises, by mass percentage: 14% lithium hexafluorophosphate, 1% ethylene sulfite, 13% p-sulfonylmethyl isocyanate, and the balance being an organic solvent, wherein the organic solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a mass ratio of EC:EMC:DMC = 2:5:3.
[0029] Example 3 An electrolyte for improving the cycle performance of lithium-ion batteries comprises, by mass percentage: 14% lithium hexafluorophosphate, 1% ethylene sulfite, 15% p-sulfonylmethyl isocyanate, and the balance being an organic solvent, wherein the organic solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a mass ratio of EC:EMC:DMC = 2:5:3.
[0030] Example 4 The only difference between Example 4 and Example 2 is that p-sulfonyl methyl isocyanate 2 is used instead of p-sulfonyl methyl isocyanate 1. The structural formula of p-sulfonyl methyl isocyanate 2 is as follows:
[0031] The synthetic route for sulfonylmethyl isocyanate compound 2 is as follows:
[0032] Example 5 The only difference between Example 5 and Example 2 is that p-sulfonyl methyl isocyanate 3 is used instead of p-sulfonyl methyl isocyanate 1. The structural formula of p-sulfonyl methyl isocyanate 3 is as follows:
[0033] The synthetic route for sulfonylmethyl isocyanate compound 3 is as follows:
[0034] The structure is confirmed as follows: 1 H NMR (400 MHz): δ 4.85 (2H, s), 7.50-7.66 (3H, 7.58(tt, J = 7.6, 1.5 Hz), 7.59 (dddd, J = 8.0, 7.6, 1.5, 0.5 Hz)), 7.80-8.03 (6H,7.86 (ddd, J = 8.6, 1.8, 0.5 Hz), 7.91 (ddd, J = 8.6, 1.9, 0.5 Hz), 7.96 (dddd, J =8.0, 1.5, 1.5, 0.5 Hz)). Example 6 The only difference between Example 6 and Example 2 is that p-sulfonyl methyl isocyanate compound 4 is used instead of p-sulfonyl methyl isocyanate compound 1. The structural formula of p-sulfonyl methyl isocyanate compound 4 is as follows:
[0035] The synthetic route for sulfonylmethyl isocyanate compound 4 is as follows:
[0036] The structure is confirmed as follows: 1 H NMR (400 MHz): δ 0.91-1.09 (4H, 1.00 (dddd, J = 8.1,7.8, 7.5, 7.5 Hz), 1.00 (dddd, J = 8.1, 7.8, 7.5, 7.5 Hz)), 2.05 (1H, dddd, J=8.1, 8.1, 7.5, 7.5 Hz), 4.75 (2H, s), 7.36 (2H, ddd, J = 8.1, 1.6, 0.4 Hz),7.64 (2H, ddd, J = 8.1, 1.5, 0.4 Hz). Example 7 The only difference between Example 7 and Example 2 is that p-sulfonyl methyl isocyanate 5 is used instead of p-sulfonyl methyl isocyanate 1. The structural formula of p-sulfonyl methyl isocyanate 5 is as follows:
[0037] The synthetic route for sulfonylmethyl isocyanate compound 5 is as follows:
[0038] The structure is confirmed as follows: 1 H NMR (400 MHz): δ 4.74 (2H, s), 5.15 (2H, s), 7.67(2H, ddd, J = 7.9, 1.5, 0.4 Hz), 7.85 (2H, ddd, J = 7.9, 2.2, 0.4 Hz). Example 8 The only difference between Example 8 and Example 2 is that p-sulfonyl methyl isocyanate 6 is used instead of p-sulfonyl methyl isocyanate 1. The structural formula of p-sulfonyl methyl isocyanate 6 is as follows:
[0039] The synthetic route for sulfonylmethyl isocyanate compound 6 is as follows:
[0040] The structure is confirmed as follows: 1 H NMR (400 MHz): δ 4.81 (2H, s), 5.52 (1H, dd, J = 11.2, 1.2 Hz), 6.28 (1H, dd, J = 18.3, 1.2 Hz), 6.58 (1H, dd, J = 18.3, 11.2 Hz), 7.60-7.74 (4H, 7.66 (ddd, J = 8.0, 1.8, 0.4 Hz), 7.68 (ddd, J= 8.0, 1.8, 0.4 Hz)). Example 9 The only difference between Example 9 and Example 2 is that p-sulfonyl methyl isocyanate 7 is used instead of p-sulfonyl methyl isocyanate 1. The structural formula of p-sulfonyl methyl isocyanate 7 is as follows:
[0041] The synthetic route for sulfonylmethyl isocyanate compound 7 is as follows:
[0042] The structure is confirmed as follows: 1 H NMR (400 MHz): δ 2.95 (1H, s), 4.81 (2H, s), 7.62-7.78 (4H, 7.69 (ddd, J = 7.9, 1.8, 0.5 Hz), 7.72 (ddd, J = 7.9, 1.8, 0.5 Hz).
[0043] Example 10 The only difference between Example 10 and Example 2 is that p-sulfonyl methyl isocyanate compound 8 is used instead of p-sulfonyl methyl isocyanate compound 1. The structural formula of p-sulfonyl methyl isocyanate compound 8 is as follows:
[0044] The synthetic route for sulfonylmethyl isocyanate compound 8 is as follows:
[0045] The structure is confirmed as follows: 1 H NMR (400 MHz): δ 3.57 (1H, dd, J = 7.7, 4.4 Hz), 3.73(1H, dd, J = 8.1, 4.4 Hz), 4.28 (1H, dd, J = 8.1, 7.7 Hz), 4.70-4.80 (2H, 4.75(s), 4.75 (s)), 7.60-7.75 (4H, 7.66 (ddd, J = 8.1, 1.5, 0.5 Hz), 7.68 (ddd, J =8.1, 2.0, 0.5 Hz)). Comparative Example 1 The only difference between Comparative Example 1 and Example 2 is that Comparative Example 1 does not contain p-sulfonylmethyl isocyanate compound 1.
[0046] Comparative Example 2 The only difference between Comparative Example 2 and Example 2 is that it does not contain vinyl sulfite.
[0047] Comparative Example 3 The only difference between Comparative Example 3 and Example 2 is that it does not contain p-sulfonylmethyl isocyanate compound 1 and vinyl sulfite.
[0048] The composition and content of lithium salt, organic solvent, and additives in the electrolytes of Examples 1-10 and Comparative Examples 1-3 are shown in Table 1 below: Table 1
[0049] Example 11 Experimental cells were assembled using the electrolytes prepared in the above examples and comparative examples, respectively. The preparation methods of the experimental cells are as follows: (1) Preparation of positive electrode The positive electrode active material silicon-based negative electrode material, the conductive agent acetylene black, and the binder polyvinylidene fluoride were mixed in a mass ratio of LFP:acetylene black:polytetrafluoroethylene = 96:2:2. N-methylpyrrolidone was added and the mixture was stirred thoroughly to form a uniform positive electrode slurry. This slurry was then uniformly coated onto a 15-micron thick aluminum foil and dried to obtain the positive electrode sheet.
[0050] (2) Preparation of negative electrode Graphite, conductive agent acetylene black, binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose were mixed in a mass ratio of graphite:acetylene black:styrene-butadiene rubber:thickener = 95:2:2:1. Deionized water was added, and the mixture was stirred thoroughly to form a uniform negative electrode slurry. This slurry was then uniformly coated onto an 8-micron thick copper foil and dried to obtain the negative electrode sheet.
[0051] (3) Preparation of experimental batteries In a dry environment with a dew point controlled below -40°C, the positive electrode sheet, separator, and negative electrode sheet prepared in step (1) are stacked in sequence to ensure that the separator completely separates the positive and negative electrode sheets. Then, the electrode sheets are wound to form a core and sealed in an aluminum-plastic film of a fixed size using adhesive tabs to form a soft-pack battery to be injected with electrolyte. Then, the electrolyte is injected into the soft-pack battery, followed by sealing, formation, aging, and capacity testing to obtain an experimental battery for testing.
[0052] The prepared batteries were subjected to the following tests: Test 1: Battery 25℃ room temperature cycle test: After capacity grading, the battery was charged at 25℃ with a constant current and constant voltage of 1C to 3.65V, and the cutoff current was 0.05C; it was then allowed to stand for 30 minutes; then discharged at a constant current of 1C to 2.0V; and allowed to stand for 30 minutes. This 1C / 1C cycle charge-discharge test was performed until the battery capacity retention reached 80%. The discharge capacity of the first cycle, Q1, was recorded as the initial discharge capacity; the discharge capacity of the battery in the nth cycle was recorded as Q. n Then the battery's discharge capacity retention rate (%) in the nth cycle = Q n / Q1×100%.
[0053] Test 2: Battery 55℃ High Temperature Cyclic Test After capacity grading, the battery was charged at 55℃ with a constant current and constant voltage of 1C to 3.65V, and the cutoff current was 0.05C; it was then allowed to stand for 30 minutes; then discharged at a constant current of 1C to 2.0V; and allowed to stand for 30 minutes. This 1C / 1C cycle charge-discharge test was performed until the battery capacity retention reached 80%. The discharge capacity of the first cycle, Q1, was recorded as the initial discharge capacity; the discharge capacity of the battery in the nth cycle was recorded as Q. n Then the battery's discharge capacity retention rate (%) in the nth cycle = Q n / Q1×100%.
[0054] Test 3: Electrolyte Acidity Test When the above-mentioned ambient temperature cycle battery has been cycled for 300 cycles, one cell was taken and disassembled in the drying room, and the electrolyte was taken for acidity testing. The test results were recorded.
[0055] The test results are shown in Table 2: Table 2
[0056] Table 2 shows that, based on the comparison results of the 25°C room temperature cycling test, the battery with both p-sulfonyl methyl isocyanate and auxiliary additives retained over 80% capacity after 1200 cycles, significantly better than the battery without p-sulfonyl methyl isocyanate. This indicates that p-sulfonyl methyl isocyanate does indeed improve the battery's room temperature cycling performance. Furthermore, compared to batteries with p-sulfonyl methyl isocyanate alone, its synergistic effect with suitable auxiliary additives is even better. The 55°C high-temperature cycling test showed similar results to the room temperature cycling test, indicating that the addition of p-sulfonyl methyl isocyanate can simultaneously form a film on both the positive and negative electrode surfaces, thus improving the battery's high-temperature cycling stability. The acidity test results in the third test show that the acidity of the battery with p-sulfonyl methyl isocyanate was effectively controlled during cycling, which itself significantly improved the battery's cycle stability and extended its cycle life.
[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. An electrolyte, characterized in that, The electrolyte includes lithium electrolyte, organic solvent, auxiliary additives, and p-sulfonylmethyl isocyanate compounds; The structural formula of the p-sulfonylmethyl isocyanate compound is shown in Formula I: In Formula I, R is selected from hydrogen atoms, halogens, and C. 1-20 Alkyl, halogen-substituted C 1-20 Alkyl, C 3-20 cycloalkyl, C 2-10 Epoxyalkyl, C 2-20 alkenyl, C 2-20 alkynyl group, C 3-20 Cycloalkenyl, C 6-26 Aryl and C 6-26 At least one of the heteroaryl groups.
2. The electrolyte according to claim 1, characterized in that, The electrolyte is made from components comprising the following components in the indicated mass percentages: Electrolyte lithium salt 10~14%; Auxiliary additives 1~5%; The p-sulfonyl methyl isocyanate compound is 1-5%; The remainder is the organic solvent.
3. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte is made from components comprising the following components in the indicated mass percentages: Electrolyte lithium salt 10~14%; Auxiliary additives 1~5%; The p-sulfonyl methyl isocyanate compound 3%; The remainder is the organic solvent.
4. The electrolyte according to claim 1 or 2, characterized in that, In Formula I, R is selected from hydrogen atoms, halogens, and C. 1-10 Alkyl, halogen-substituted C 1-10 Alkyl, C 3-20 cycloalkyl, C 3-5 Epoxyalkyl, C 2-10 alkenyl, C 2-10 alkynyl group, C 3-10 Cycloalkenyl, C 6-16 Aryl and C 6-16 At least one of the heteroaryl groups.
5. The electrolyte according to claim 1 or 2, characterized in that, The p-sulfonylmethyl isocyanate compound is selected from at least one of the following structural formulas: 。 6. The electrolyte according to claim 1 or 2, characterized in that, The electrolyte lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium di(oxalate)borate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide.
7. The electrolyte according to claim 1 or 2, characterized in that, The organic solvent is selected from at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propyl methyl carbonate, ethylene carbonate, and propylene carbonate.
8. The electrolyte according to claim 1 or 2, characterized in that, The auxiliary additive is selected from at least one of vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, vinyl sulfite, 1,3-propane sulpholactone, 1,4-butane sulpholactone, propylene sulfate, and ethylene ethylene carbonate.
9. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and the electrolyte according to any one of claims 1-8.
10. The lithium-ion battery according to claim 9, characterized in that, The positive electrode sheet includes a positive current collector and a positive active material layer composited on the positive current collector. The positive active material layer includes a positive active material, which is selected from at least one of lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt manganese oxide, and lithium iron phosphate. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer composited on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, which is at least one of carbon-containing materials, titanium oxide, silicon, lithium, and lithium alloys. The diaphragm is made of at least one of polyethylene, polypropylene and polyvinylidene fluoride.