Semi-solid battery with long service life and high safety and preparation method thereof

Abstract

The invention provides a long-life and high-safety semi-solid battery and a preparation method thereof, and belongs to the technical field of semi-solid batteries. The method comprises the following steps: injecting an electrolyte A into a baked battery cell, and performing high-temperature activation and high-temperature formation; injecting the formed battery cell into the electrolyte B, and carrying out high-temperature aging; injecting the aged battery cell into the electrolyte C, sealing, and standing at normal temperature; and carrying out high-temperature polymerization and capacity grading to obtain the product. A three-time liquid injection process is adopted, the monomer and the initiator are separately arranged in the first injection and the third injection, non-uniformity caused by polymerization of the monomer and the initiator in the transportation process and the infiltration process can be prevented, the monomer and the initiator are not added in the second injection, it is guaranteed that the second injection is sufficient in vinylene carbonate VC, and the cycle performance is guaranteed; and an initiator is added during third injection, and the third injection does not contain lithium salt, so that infiltration is promoted, and the polymerization uniformity is ensured. The semi-solid energy storage battery prepared by the invention has the characteristics of long service life and high safety performance.

Description

Technical Field

[0001] The present invention relates to the technical field of semi-solid batteries, and in particular to a long-life, high-safety semi-solid battery and a preparation method thereof. Background Art

[0002] Lithium iron phosphate batteries have broad market prospects in the field of electric energy storage in the future. Cost, as one of the constraints on the large-scale application of energy storage batteries in the future, not only refers to the one-time investment cost, but also includes the cost of battery raw materials, manufacturing costs, system-level cooling equipment investment and maintenance costs; to achieve energy storage parity, the energy storage industry must move towards large-scale and healthy development, and solve the difficulties in business models, safety and stability, levelization, and LCOE.

[0003] From a technical perspective, the evolution of energy storage products is mainly reflected in large capacity, long life, high power, and high safety, centering on safety and cost reduction. The increase in the service life of lithium batteries means that the cost of the entire life cycle of the energy storage system will be reduced to a certain extent. When the cycle life of the energy storage battery is increased to 10,000 times, the energy storage cost can be reduced to less than 1,000 yuan per kilowatt-hour. The traditional injection method of existing energy storage lithium-ion batteries is one-time injection, but this traditional injection method is not conducive to the long cycle life performance of energy storage lithium-ion batteries. In order to improve the cycle life of energy storage batteries, lithium replenishment technology and vinyl carbonate VC gradient two injections are generally used. The so-called vinyl carbonate VC gradient two injections means that the vinyl carbonate VC of one injection is 1.5% to 2.5%, and the vinyl carbonate VC of the second injection is greater than 8%. The safety issues caused by large capacity are also becoming more and more the key to the application of energy storage batteries, especially overcharging and acupuncture. In order to solve the safety problems, people began to add flame retardant additives and overcharge additives to the electrolyte, but the addition of flame retardant additives and overcharge additives will cause a significant reduction in performance. In addition, the preparation methods of the semi-solid electrolytes reported so far cannot match the existing battery manufacturing processes, making them difficult to promote on a large scale. They also have poor performance in full-battery applications, and their electrochemical performance needs to be further improved compared to liquid electrolytes.

[0004] Based on this, the present invention proposes a long-life, high-safety semi-solid-state battery and its injection process. Summary of the invention

[0005] The present invention provides a long-life and highly safe semi-solid battery and a preparation method thereof, the purpose of which is to solve the above-mentioned problems existing in the background technology.

[0006] In order to achieve the above-mentioned purpose, the embodiment of the present invention provides a long-life, high-safety semi-solid battery and a preparation method thereof. The present invention adopts a three-time injection process, separates the monomer and the initiator in the first injection and the third injection, prevents the two from polymerizing during transportation and infiltration, and causes uneven polymerization. No monomer and initiator are added in the second injection to ensure that the second injection has enough vinylene carbonate VC to ensure the cycle performance. In the third injection, the initiator is added and the third injection does not contain lithium salt, which promotes infiltration and ensures polymerization uniformity. The present invention can form a long-life, high-safety semi-solid energy storage battery through the electrolyte formula and the injection process.

[0007] The purpose of the embodiment of the present invention is to provide a method for preparing a semi-solid-state battery with a long life and high safety, comprising the following steps:

[0008] S1: injecting electrolyte A into the baked battery cell for high temperature activation and high temperature formation;

[0009] S2: injecting the formed battery into electrolyte B for high temperature aging;

[0010] S3: inject electrolyte C into the aged battery cell and seal it, and let it stand at room temperature;

[0011] S4: Perform high temperature polymerization and separate the contents to obtain.

[0012] According to one aspect of the embodiment of the present invention, in step S1, the temperature of high temperature activation is 45-50° C. and the time is 72-96 hours.

[0013] According to one aspect of an embodiment of the present invention, in step S2, the high temperature aging temperature is 45-50° C. and the time is 72-96 hours.

[0014] According to one aspect of an embodiment of the present invention, in step S3, the standing time at room temperature is 24 to 72 hours.

[0015] According to one aspect of the embodiment of the present invention, in step S4, the temperature of the high temperature polymerization is 45 to 80° C., and the time is 2 to 24 hours.

[0016] According to one aspect of an embodiment of the present invention, the electrolyte A comprises 3% to 8% monomers, 70.5% to 86% solvents, 1% to 6% additives and 10% to 15.5% lithium salts; the solvent is ethylene carbonate EC, dimethyl carbonate DMC or ethyl methyl carbonate EMC; the additive is at least one of fluoroethylene carbonate FEC containing vinylene carbonate VC, LiODFP, vinylene sulfate DTD, tris(trimethylsilyl) phosphate TMSP, methylene disulfonate MMDS, and LiPO2F2; the monomer The body includes at least one of polyethylene glycol methyl ether acrylate PEGMEA, tetraethylene glycol diacrylate TEGDA, pentaerythritol triacrylate PETA, polyethylene glycol diacrylate PEGDA, polymethyl methacrylate PMMA, methyl methacrylate MMA, triethylene glycol dimethacrylate TEGDMA, ethylene glycol dimethacrylate EGDMA, methyl methacrylate MMA, 4,4-bismaleimidodiphenylmethane, pentaerythritol tetraacrylate PET4A, and pentaerythritol triacrylate PETA.

[0017] According to one aspect of an embodiment of the present invention, the electrolyte B includes 66.5% to 82% solvent, 10% to 15.5% lithium salt and 8% to 18% additive; the lithium salt is LiPF6 and LiFSI; the additive is vinylene carbonate VC; the solvent is vinyl carbonate EC, dimethyl carbonate DMC or ethyl methyl carbonate EMC.

[0018] According to one aspect of an embodiment of the present invention, the electrolyte C includes 0.03% to 0.10% initiator and 99.90% to 99.97% solvent; the solvent is ethylene carbonate EC, dimethyl carbonate DMC or ethyl methyl carbonate EMC; the initiator includes at least one of azobisisobutyronitrile AIBN, dimethyl azobisisobutyrate AIBME, and benzoyl peroxide BPO.

[0019] Based on a general inventive concept, an embodiment of the present invention provides a long-life and highly safe semi-solid-state battery obtained by the above-mentioned preparation method.

[0020] The above scheme of the present invention has the following beneficial effects:

[0021] (1) The present invention adopts a three-shot liquid injection process, separating the monomer and the initiator in the first shot and the third shot, to prevent polymerization during transportation and the infiltration process, resulting in uneven polymerization. No monomer and initiator are added in the second shot to ensure that there is enough vinylene carbonate VC in the second shot to ensure the cycle performance. Initiator is added in the third shot and the third shot does not contain lithium salt, which promotes infiltration and ensures polymerization uniformity.

[0022] (2) The present invention can form a long-life and highly safe semi-solid energy storage battery through electrolyte formulation and injection process. DETAILED DESCRIPTION

[0023] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, they are described in detail below in conjunction with specific embodiments.

[0024] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0025] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0026] The traditional method of liquid injection for existing energy storage lithium-ion batteries is one-time liquid injection, but this traditional liquid injection method is not conducive to the long cycle life performance of energy storage lithium-ion batteries. To improve the cycle life of energy storage batteries, lithium supplementation technology and vinyl carbonate VC gradient two-injection are generally used, but the safety issues caused by large capacity, especially overcharging and puncture problems, need to be solved urgently. In addition, the preparation method of the semi-solid electrolyte reported so far cannot match the existing battery manufacturing process, making it difficult to achieve large-scale promotion, and the performance in full battery applications is poor, and compared with liquid electrolytes, the electrochemical performance needs to be further improved.

[0027] An embodiment of the present invention provides a method for preparing a long-life and highly safe semi-solid-state battery, comprising the following steps:

[0028] S1: injecting electrolyte A into the baked battery cell for high temperature activation and high temperature formation;

[0029] S2: injecting the formed battery into electrolyte B for high temperature aging;

[0030] S3: inject electrolyte C into the aged battery cell and seal it, and let it stand at room temperature;

[0031] S4: Perform high temperature polymerization and separate the contents to obtain.

[0032] According to one aspect of the embodiment of the present invention, in step S1, the temperature of high temperature activation is 45-50° C. and the time is 72-96 hours.

[0033] According to one aspect of an embodiment of the present invention, in step S2, the high temperature aging temperature is 45-50° C. and the time is 72-96 hours.

[0034] According to one aspect of an embodiment of the present invention, in step S3, the standing time at room temperature is 24 to 72 hours.

[0035] According to one aspect of the embodiment of the present invention, in step S4, the temperature of the high temperature polymerization is 45 to 80° C., and the time is 2 to 24 hours.

[0036] According to one aspect of an embodiment of the present invention, the electrolyte A comprises 3% to 8% monomers, 70.5% to 86% solvents, 1% to 6% additives and 10% to 15.5% lithium salts; the solvent is ethylene carbonate EC, dimethyl carbonate DMC or ethyl methyl carbonate EMC; the additive is at least one of fluoroethylene carbonate FEC containing vinylene carbonate VC, LiODFP, vinylene sulfate DTD, tris(trimethylsilyl) phosphate TMSP, methylene disulfonate MMDS, and LiPO2F2; the monomer The body includes at least one of polyethylene glycol methyl ether acrylate PEGMEA, tetraethylene glycol diacrylate TEGDA, pentaerythritol triacrylate PETA, polyethylene glycol diacrylate PEGDA, polymethyl methacrylate PMMA, methyl methacrylate MMA, triethylene glycol dimethacrylate TEGDMA, ethylene glycol dimethacrylate EGDMA, methyl methacrylate MMA, 4,4-bismaleimidodiphenylmethane, pentaerythritol tetraacrylate PET4A, and pentaerythritol triacrylate PETA.

[0037] According to one aspect of an embodiment of the present invention, the electrolyte B includes 66.5% to 82% solvent, 10% to 15.5% lithium salt and 8% to 18% additive; the lithium salt is LiPF6 and LiFSI; the additive is vinylene carbonate VC; the solvent is vinyl carbonate EC, dimethyl carbonate DMC or ethyl methyl carbonate EMC.

[0038] According to one aspect of an embodiment of the present invention, the electrolyte C includes 0.03% to 0.10% initiator and 99.90% to 99.97% solvent; the solvent is ethylene carbonate EC, dimethyl carbonate DMC or ethyl methyl carbonate EMC; the initiator includes at least one of azobisisobutyronitrile AIBN, dimethyl azobisisobutyrate AIBME, and benzoyl peroxide BPO.

[0039] Based on a general inventive concept, an embodiment of the present invention provides a long-life and highly safe semi-solid-state battery obtained by the above-mentioned preparation method.

[0040] Advantages of the implementation of the present invention:

[0041] (1) The present invention adopts a three-time injection process, separating the monomer and the initiator in the first and third injections to prevent polymerization during transportation and infiltration, resulting in uneven polymerization. No monomer and initiator are added in the second injection to ensure that there is enough vinylene carbonate VC in the second injection to ensure the cycle performance. Initiator is added in the third injection and the third injection does not contain lithium salt to promote infiltration and ensure polymerization uniformity. The monomer is added first to make the monomer penetrate more evenly in the pole piece. The subsequent initiator combines with the monomer to form a gel inside the battery cell, so that the electrolyte fills all the pole pieces.

[0042] (2) The present invention can form a long-life and highly safe semi-solid energy storage battery through electrolyte formulation and injection process.

[0043] The following is a detailed description of the battery cell. The assembly process of the battery cell mentioned below is: assemble the positive electrode sheet whose main material is lithium iron phosphate, the negative electrode sheet whose main material is graphite, and the separator into the shell, weld the cover plate, and set aside.

[0044] Example 1

[0045] A method for preparing a long-life and highly safe semi-solid-state battery comprises the following steps:

[0046] S1: inject the baked battery into electrolyte A (composition includes: monomer is 5% PEGMEA, solvent is 23.5% EC / 23.5% DMC / 31.5% EMC, lithium salt is 12.5% ​​LiPF6+LiFSI, additive is 2% VC+1% FEC), activate at high temperature of 45°C for 96h, and form;

[0047] S2: Inject the formed battery into electrolyte B (composition includes: solvent is 22% EC / 22% DMC / 29.5% EMC, lithium salt is 12.5% ​​LiPF6+LiFSI, additive is 14% VC), and age at 45°C for 96h;

[0048] S3: inject electrolyte C (composition includes: initiator is 0.06% AIBN, solvent is 30% EC / 30% DMC / 39.94% EMC) into the aged battery cell and seal it, and let it stand at room temperature for 72 hours;

[0049] S4: polymerize at 45℃ for 24h, separate the contents, and obtain;

[0050] Example 2

[0051] The difference from Example 1 is that the additive in the electrolyte B is 18% vinylene carbonate VC, and the other steps and parameters are the same as those in Example 1.

[0052] Example 3

[0053] The difference from Example 1 is that the initiator in electrolyte C is AIBME, and the other steps and parameters are the same as those in Example 1.

[0054] Comparative Example 1

[0055] A method for preparing a semi-solid battery comprises the following steps:

[0056] (1) injecting the electrolyte (composition includes: monomer is 5% PEGMEA, solvent is 23.0% EC / 23.0% DMC / 33.44% EMC, lithium salt is 12.5% ​​LiPF6+LiFSI, additive is 2% VC+1% FEC, initiator is 0.06% AIBN) into the baked battery cell and directly standing at room temperature for 96 hours;

[0057] (2) Polymerization at 60°C for 12 h;

[0058] (3) High temperature formation;

[0059] (4) Aging at 45°C for 72 seconds; dividing by volume to obtain the product.

[0060] In this comparative example, since the electrolyte including monomers and initiators causes wetting difficulties, the gel is uneven after high-temperature polymerization. Although the safety performance is improved to a certain extent, the life span is reduced.

[0061] Comparative Example 2

[0062] A method for preparing a semi-solid battery comprises the following steps:

[0063] (1) injecting the electrolyte (composition includes: monomer is 5% PEGMEA, solvent is 23.5% EC / 23.5% DMC / 31.5% EMC, lithium salt is 12.5% ​​LiPF6+LiFSI, additive is 2% VC+1% FEC) into the baked battery cell and activating at 45°C for 96h;

[0064] (2) High-temperature formation; then, the electrolyte (composition includes: initiator is 0.06% AIBN, additives are 14% VC, 22% EC / 22% DMC / 29.5% EMC, lithium salt is 12.5% ​​LiPF6+LiFSI) is injected into the formed battery cell and sealed;

[0065] (3) Aging at 45°C for 96 hours, and then separating the contents to obtain the product.

[0066] In this comparative example, since the initiator and VC have polymerized before injection, the electrolyte B is milky white and viscous, which makes injection difficult. After being injected into the battery, it can hardly polymerize with the monomer to form a gel electrolyte, and affects the lithium ion transmission, causing the life to decay rapidly.

[0067] Comparative Example 3

[0068] The difference from Example 1 is that the monomer in electrolyte A is 2% PEGMEA, and the other steps and parameters are the same as Example 1. The capacity retention rate of the semi-solid battery prepared in this comparative example after 1000 cycles is not as good as that in Example 1, and overcharging can cause fire and explosion, and the safety performance is unstable.

[0069] The semi-solid batteries prepared in the above-mentioned embodiments and comparative examples were tested, and the test results are shown in Table 1 below.

[0070] Table 1

[0071]

[0072] It can be seen from Table 1 that the semi-solid energy storage battery prepared by the present invention has a high capacity retention rate after 1000 cycles of 1p charging, and no puncture or overcharge occurs, and has the advantages of long service life and high safety performance.

[0073] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a long-life, high-safety semi-solid-state battery, characterized in that: The steps include: S1: injecting electrolyte A into the baked battery cell for high temperature activation and high temperature formation; S2: injecting the formed battery into electrolyte B for high temperature aging; S3: inject electrolyte C into the aged battery cell and seal it, and let it stand at room temperature; S4: Perform high temperature polymerization and separate the contents to obtain.

2. The method for preparing a long-life and high-safety semi-solid-state battery according to claim 1, characterized in that: In step S1, the temperature of high temperature activation is 45-50° C. and the time is 72-96 hours.

3. The method for preparing a long-life and high-safety semi-solid-state battery according to claim 1, characterized in that: In step S2, the high temperature aging temperature is 45-50°C and the time is 72-96 hours.

4. The method for preparing a long-life and high-safety semi-solid-state battery according to claim 1, characterized in that: In step S3, the standing time at room temperature is 24 to 72 hours.

5. The method for preparing a long-life and high-safety semi-solid-state battery according to claim 1, characterized in that: In step S4, the temperature of high temperature polymerization is 45 to 80° C., and the time is 2 to 24 hours.

6. The method for preparing a long-life and high-safety semi-solid-state battery according to claim 1, characterized in that: The electrolyte A includes 3% to 8% monomers, 70.5% to 86% solvents, 1% to 6% additives and 10% to 15.5% lithium salts; the lithium salts are LiPF6 and LiFSI; the solvents are ethylene carbonate, dimethyl carbonate or ethyl methyl carbonate; the additives are at least one of fluoroethylene carbonate containing vinylene carbonate, LiODFP, vinylene sulfate, tri(trimethylsilyl) phosphate, methylene disulfonate, and LiPO2F2; the monomers include at least one of polyethylene glycol methyl ether acrylate, tetraethylene glycol diacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, polymethyl methacrylate, methyl methacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, methyl methacrylate, 4,4-bismaleimidodiphenylmethane, pentaerythritol tetraacrylate, and pentaerythritol triacrylate.

7. The method for preparing a long-life and high-safety semi-solid-state battery according to claim 1, characterized in that: The electrolyte B includes 66.5% to 82% solvent, 10% to 15.5% lithium salt and 8% to 18% additive; the lithium salt is LiPF6 and LiFSI; the additive is vinylene carbonate; the solvent is vinyl carbonate, dimethyl carbonate or ethyl methyl carbonate.

8. The method for preparing a long-life and high-safety semi-solid battery according to claim 1, characterized in that: The electrolyte C comprises 0.03% to 0.10% of an initiator and 99.90% to 99.97% of a solvent; the solvent is ethylene carbonate, dimethyl carbonate or ethyl methyl carbonate; the initiator comprises at least one of azobisisobutyronitrile, dimethyl azobisisobutyrate and benzoyl peroxide.

9. A long-life and highly safe semi-solid-state battery obtained by the preparation method according to any one of claims 1 to 8.

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