A polymer composite solid electrolyte, a solid electrolyte membrane, and a solid-state battery

Abstract

The application discloses a polymer composite solid electrolyte, which comprises a polyalkylene oxide polymer, a Lewis acid type lithium salt and a lithiumophilic metal perchlorate, is prepared by mixing a cyclic ether monomer, the Lewis acid type lithium salt and the lithiumophilic metal perchlorate, uniformly stirring, and then high-temperature solidification. The application further discloses a solid electrolyte film and a solid battery prepared from the polymer composite solid electrolyte. The polymer composite solid electrolyte can operate under high voltage conditions, has good cycle performance, causes less pollution in preparation, and has a wider application range.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and more particularly to a polymer composite solid electrolyte, a solid electrolyte membrane, and a solid-state battery. Background Technology

[0002] In recent years, fires and explosions involving new energy vehicles have become increasingly frequent, and safety hazards remain a major concern for consumers. The main causes of these fires include the vehicle itself, the power battery system, the power battery structure, individual battery cells, and ignition by external heat sources. Among these factors, the individual battery cells are crucial to the safety of new energy vehicles; therefore, ensuring the safety of individual battery cells is of paramount importance to fundamentally addressing safety issues.

[0003] Solid-state batteries are an important way to solve the safety problem of individual battery cells. Solid-state batteries themselves do not contain flammable organic electrolytes and can remain non-flammable and non-explosive even in harsh environments. Solid-state batteries can be classified into polymer, oxide, sulfide, and halide batteries according to their electrolytes. Among them, polymer batteries have better processing performance and are the easiest to mass-produce. Traditional polymer electrolyte membrane production involves mixing polymers, lithium salts, or dopants with organic solvents, stirring them evenly, and then coating them to a certain thickness to obtain a solid electrolyte membrane. This method requires the use of large amounts of toxic solvents, and the volatilization of organic solvents causes serious environmental pollution. In addition, the PEO system polymer electrolyte currently mass-produced by Bolloré in France requires high-temperature operation and has a voltage window of <3.9V, which cannot be matched with high-voltage cathode materials, greatly limiting its application range. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a polymer composite solid electrolyte, a solid electrolyte membrane, and a solid battery.

[0005] The present invention proposes a polymer composite solid electrolyte comprising a polyoxyethylene polymer, a Lewis acid lithium salt, and a lithium-philic metal perchlorate.

[0006] Preferably, the polymer composite solid electrolyte is prepared by mixing cyclic ether monomers, Lewis acid lithium salts, and lithium-philic metal perchlorates, stirring until homogeneous, and then curing at high temperature.

[0007] Preferably, the mass ratio of the cyclic ether monomer, Lewis acid lithium salt, and lithium-loving metal perchlorate is (70-80):(10-20):(3-10).

[0008] Preferably, the cyclic ether monomer is at least one of 1,3-dioxopentane, dioxane, and tetrahydrofuran.

[0009] Preferably, the Lewis acid type lithium salt is at least one of LiPF6, LiClO4, LiDFOB, LiBF4, and LiTFSI.

[0010] Preferably, the lithium-loving metal perchlorate is at least one of Mg(ClO4)2, Zn(ClO4)2, Sn(ClO4)2, and AgClO4.

[0011] Preferably, the stirring time is 2 to 3 hours.

[0012] Preferably, the high-temperature curing temperature is 80–120°C.

[0013] A polymer composite solid electrolyte membrane is obtained by melting and extruding the polymer composite solid electrolyte into a membrane.

[0014] Preferably, the temperature of the melt extrusion film formation is 80–120°C.

[0015] Preferably, the thickness of the polymer composite solid electrolyte membrane is 10–30 μm.

[0016] A solid-state battery includes a positive electrode, a negative electrode, and a polymer composite solid electrolyte membrane, wherein the polymer composite solid electrolyte membrane is located between the positive electrode and the negative electrode.

[0017] The positive electrode sheet includes a positive current collector and a positive active layer disposed on the positive current collector. The positive active layer includes a positive active material, a conductive agent, and the polymer composite solid electrolyte.

[0018] Preferably, in the positive electrode active layer, the mass ratio of the positive electrode active material, the conductive agent and the polymer composite solid electrolyte is (70-90):5:(15-30).

[0019] Preferably, the positive electrode active material is a high-nickel ternary 811 material; the conductive agent is VGCF.

[0020] Preferably, the negative electrode is a lithium-copper composite strip with a thickness of 100 μm.

[0021] The beneficial effects of this invention are as follows:

[0022] The polymer composite solid electrolyte of this invention comprises a polyoxyethylene polymer, a Lewis acid lithium salt, and a lithium-metal perchlorate. It is obtained by solidifying a cyclic ether monomer, a Lewis acid lithium salt, and a lithium-metal perchlorate. The cyclic ether monomer serves as a raw material for the polymerization reaction to generate the polyoxyethylene polymer and can also act as a solvent, significantly reducing pollution problems associated with traditional processes. The Lewis acid lithium salt acts as a catalyst and ion-conducting agent, avoiding the need for additional polymer initiators, greatly reducing interference from impurities, and lowering costs. In the lithium-metal perchlorate, the perchlorate anion can form a stable buffer layer on both sides of the positive and negative electrodes, preventing continuous side reactions between the positive electrode active components and lithium metal with the hydroxide ions of the polymer electrolyte. The lithium-metal cation facilitates uniform lithium metal deposition, improving cycle performance and significantly increasing the high-voltage window of the solid electrolyte, enabling it to operate at voltages >3.9 GHz. This allows it to be matched with high-voltage positive electrode materials, resulting in a wider range of applications. Detailed Implementation

[0023] The technical solution of the present invention will now be described in detail through specific embodiments.

[0024] Example 1

[0025] Preparation of polymer composite solid electrolytes:

[0026] 1,3-dioxapentane, LiDFOB and Zn(ClO4)2 were mixed in a mass ratio of 80:15:5, stirred for 3 hours, and then cured at 80°C to obtain a polymer composite solid electrolyte.

[0027] Preparation of polymer composite solid electrolyte membrane:

[0028] The above-mentioned polymer composite solid electrolyte was melt-extruded into a film at 80°C using a T-die melt extruder. The T-die gap was adjusted to 10 μm to obtain a polymer composite solid electrolyte film with a thickness of 10 μm. The above-mentioned polymer composite solid electrolyte film was then wound up and assembled into a blocking electrode, and its room temperature ionic conductivity was tested.

[0029] Assemble solid-state batteries:

[0030] Weigh 0.64 kg of high-nickel ternary 811 material and 0.04 kg of carbon black into a 1 L mixing tank, add 0.8 L of NMP and stir until homogeneous. Then add 0.16 kg of the above polymer composite solid electrolyte and stir for 4 hours to obtain a uniform positive electrode slurry. Use an extrusion coating machine to coat the positive electrode slurry onto aluminum foil, with a single-sided areal density of 46.0 mg / cm³. 2 The positive electrode sheet is die-cut into pieces with an effective area of ​​100 cm². 2 The surface of the lithium copper composite strip negative electrode sheet is die-cut into an effective area of ​​103 cm². 2The polymer composite solid electrolyte membrane was hot-pressed onto the surface of the lithium copper composite strip negative electrode. A pouch cell was assembled by stacking 20 positive and 21 negative electrodes. The pouch cell was then hot-pressed at 80°C for 0.5 hours using a hot press to obtain a solid-state battery. The capacity, initial efficiency, and cycle performance of the all-solid-state battery were tested under the following conditions: 25°C, 0.1C rate, voltage window of 2.8–4.25V, and 100 cycles.

[0031] Example 2

[0032] Preparation of polymer composite solid electrolytes:

[0033] Dioxane, LiBF4 and Mg(ClO4)2 were mixed in a mass ratio of 77:20:3, stirred for 2 hours, and then cured at 90°C to obtain a polymer composite solid electrolyte.

[0034] Preparation of polymer composite solid electrolyte membrane:

[0035] The polymer composite solid electrolyte was melt-extruded into a film at 100°C using a T-die melt extruder. The T-die gap was adjusted to 20 μm to obtain a polymer composite solid electrolyte film with a thickness of 20 μm. The polymer composite solid electrolyte film was then wound up and assembled into a blocking electrode, and its room temperature ionic conductivity was tested.

[0036] Assemble solid-state batteries:

[0037] Weigh 1.6 kg of high-nickel ternary 811 material and 0.1 kg of carbon black into a 5 L mixing tank, add 2 L of NMP and stir until homogeneous. Then add 0.4 kg of the above polymer composite solid electrolyte and stir for 6 hours to obtain a uniform positive electrode slurry. Use an extrusion coating machine to coat the positive electrode slurry onto aluminum foil, with a single-sided areal density of 42.0 mg / cm³. 2 The positive electrode sheet is die-cut into pieces with an effective area of ​​100 cm². 2 The surface of the lithium copper composite strip negative electrode sheet is die-cut into an effective area of ​​103 cm². 2 The polymer composite solid electrolyte membrane was hot-pressed onto the surface of the lithium copper composite strip negative electrode. The 21-layer positive electrode and 22-layer negative electrode were assembled into a pouch cell by stacking. The pouch cell was then hot-pressed at 100°C for 0.5 hours using a hot flat press to obtain a solid-state battery. The capacity, first-efficiency performance, and cycle performance of the all-solid-state battery were tested under the following conditions: 25°C, 0.1C rate, voltage window of 2.8–4.25V, and 100 cycles.

[0038] Example 3

[0039] Preparation of polymer composite solid electrolytes:

[0040] Tetrahydrofuran, LiPF6 and Sn(ClO4)2 were mixed in a mass ratio of 70:20:10, stirred for 3 hours, and then cured at 105℃ to obtain a polymer composite solid electrolyte.

[0041] Preparation of polymer composite solid electrolyte membrane:

[0042] The polymer composite solid electrolyte was melt-extruded into a film at 90°C using a T-die melt extruder. The T-die gap was adjusted to 30 μm to obtain a polymer composite solid electrolyte film with a thickness of 30 μm. The polymer composite solid electrolyte film was then wound up and assembled into a blocking electrode, and its room temperature ionic conductivity was tested.

[0043] Assemble solid-state batteries:

[0044] Weigh 0.8 kg of high-nickel ternary 811 material and 0.05 kg of carbon black into a 1 L mixing tank, add 1 L of NMP and stir until homogeneous. Then add 0.2 kg of the above polymer composite solid electrolyte and stir for 5 hours to obtain a uniform positive electrode slurry. Use an extrusion coating machine to coat the positive electrode slurry onto aluminum foil, with a single-sided areal density of 48.0 mg / cm³. 2 The positive electrode sheet is die-cut into pieces with an effective area of ​​100 cm². 2 The surface of the lithium copper composite strip negative electrode sheet is die-cut into an effective area of ​​103 cm². 2 The polymer composite solid electrolyte membrane was hot-pressed onto the surface of the lithium copper composite strip negative electrode. The 21-layer positive electrode and 22-layer negative electrode were assembled into a pouch cell by stacking. The pouch cell was then hot-pressed at 80°C for 0.5 hours using a hot flat press to obtain a solid-state battery. The capacity, first efficiency, and cycle performance of the all-solid-state battery were tested under the following conditions: 25°C, 0.1C rate, voltage window of 2.8–4.25V, and 100 cycles.

[0045] Comparative Example 1

[0046] Preparation of polymer composite solid electrolytes:

[0047] 1,3-dioxane and LiDFOB were mixed at a mass ratio of 80:20, stirred for 3 hours, and then cured at 80°C to obtain a polymer composite solid electrolyte.

[0048] Preparation of polymer composite solid electrolyte membrane:

[0049] The above-mentioned polymer composite solid electrolyte was melt-extruded into a film at 80°C using a T-die melt extruder. The T-die gap was adjusted to 10 μm to obtain a polymer composite solid electrolyte film with a thickness of 10 μm. The above-mentioned polymer composite solid electrolyte film was then wound up and assembled into a blocking electrode, and its room temperature ionic conductivity was tested.

[0050] Assemble solid-state batteries (method as in Example 1):

[0051] Weigh 0.64 kg of high-nickel ternary 811 material and 0.04 kg of carbon black into a 1 L mixing tank, add 0.8 L of NMP and stir until homogeneous. Then add 0.16 kg of the above polymer composite solid electrolyte and stir for 4 hours to obtain a uniform positive electrode slurry. Use an extrusion coating machine to coat the positive electrode slurry onto aluminum foil, with a single-sided areal density of 46.0 mg / cm³. 2 The positive electrode sheet is die-cut into pieces with an effective area of ​​100 cm². 2 The surface of the lithium copper composite strip negative electrode sheet is die-cut into an effective area of ​​103 cm². 2 The polymer composite solid electrolyte membrane was hot-pressed onto the surface of the lithium copper composite strip negative electrode. A pouch cell was assembled by stacking 20 positive and 21 negative electrodes. The pouch cell was then hot-pressed at 80°C for 0.5 hours using a hot press to obtain a solid-state battery. The capacity, initial efficiency, and cycle performance of the all-solid-state battery were tested under the following conditions: 25°C, 0.1C rate, voltage window of 2.8–4.25V, and 100 cycles.

[0052] Table 1 shows the room temperature ionic conductivity of the solid electrolytes in Examples 1-3 and Comparative Example 1, as well as the capacity, first efficiency, and cycle life of the assembled all-solid-state batteries.

[0053] Table 1

[0054]

[0055] The test results in Table 1 show that the solid-state batteries of Examples 1 to 3 can operate at a high voltage of >3.9, while the solid-state battery of Comparative Example 1 cannot operate at a high voltage. This indicates that the electrolyte of the present invention can be used in cathode materials that match high voltage, thus expanding its application range.

[0056] 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. A polymer composite solid electrolyte, characterized in that, The polymer composite solid electrolyte is prepared by mixing cyclic ether monomers, Lewis acid lithium salts and lithium-philic metal perchlorates, stirring evenly, and then curing at high temperature at 80~120℃. The mass ratio of the cyclic ether monomer, Lewis acid lithium salt, and lithium-philic metal perchlorate is (70~80):(10~20):(3~10); The cyclic ether monomer is at least one of 1,3-dioxopentane, dioxane, and tetrahydrofuran; the Lewis acid lithium salt is at least one of LiPF6, LiClO4, LiDFOB, LiBF4, and LiTFSI; and the lithium-philic metal perchlorate is Sn(ClO4)2.

2. The polymer composite solid electrolyte according to claim 1, characterized in that, The stirring time is 2-3 hours.

3. A polymer composite solid electrolyte membrane, characterized in that, It is prepared by melting and extruding the polymer composite solid electrolyte as described in claim 1 or 2 into a film.

4. The polymer composite solid electrolyte membrane according to claim 3, characterized in that, The temperature for melt extrusion film formation is 80~120℃.

5. The polymer composite solid electrolyte membrane according to claim 3, characterized in that, The thickness of the polymer composite solid electrolyte membrane is 10~30μm.

6. A solid-state battery, characterized in that, The invention includes a positive electrode, a negative electrode, and a polymer composite solid electrolyte membrane as described in any one of claims 3 to 5, wherein the polymer composite solid electrolyte membrane is located between the positive electrode and the negative electrode. The positive electrode sheet includes a positive current collector and a positive active layer disposed on the positive current collector. The positive active layer includes a positive active material, a conductive agent, and the polymer composite solid electrolyte as described in claim 1 or 2.

7. The solid-state battery according to claim 6, characterized in that, In the positive electrode active layer, the mass ratio of the positive electrode active material, the conductive agent and the polymer composite solid electrolyte is (70~90):5:(15~30).

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