A negative electrode structure and an all-solid-state battery containing it

Abstract

This invention discloses a negative electrode structure and an all-solid-state battery containing the same. The negative electrode structure includes a halide solid electrolyte and a metal negative electrode, with a thin film layer of ≤5μm thickness disposed between the halide solid electrolyte and the metal negative electrode. The thin film layer is a composite sulfide film or a polymer film formed by in-situ curing. This negative electrode structure, by setting a uniform thin film layer with high ionic conductivity, thin thickness, and certain mechanical strength between the halide solid electrolyte and the metal negative electrode, and assembling it with the metal negative electrode and the halide solid electrolyte into an integrated negative electrode structure, can completely separate the halide solid electrolyte and the negative electrode, suppress interfacial reactions, reduce interfacial impedance, avoid the use of a thicker sulfide transition layer, and improve battery safety while matching high-voltage positive electrode materials, thereby significantly improving the energy density and performance of the all-solid-state battery.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, specifically relating to a negative electrode structure and an all-solid-state battery containing the negative electrode structure. Background Technology

[0002] In secondary batteries, traditional organic electrolytes pose safety hazards due to their flammability. Therefore, replacing organic electrolytes with safer solid-state electrolytes (SSEs) is a current research trend. All-solid-state batteries not only offer better safety but also allow for compatibility with higher-voltage cathode materials and lower-voltage metal anode materials, resulting in higher energy density.

[0003] Currently, the solid electrolytes used in common solid-state batteries are mainly lithium / sodium ion oxides, sulfides, and borohydrides, all of which exhibit high ionic conductivity. Among them, sulfides have the highest ionic conductivity (e.g., Na3PS4, Li6PS5Cl, with ionic conductivity ranging from 0.1 to 10 mS·cm). -1 While its chemical and electrochemical stability is close to or even higher than that of organic liquid electrolytes, its capacity decays rapidly when matched with a high-voltage cathode. Oxide solid electrolytes, such as Na3Zr2Si2PO4, are also problematic. 12 These materials are relatively hard and do not easily deform, resulting in poor physical contact between them and electrode materials. This severely hinders the transport of lithium / sodium ions at the interface, leading to a deterioration in battery performance.

[0004] Halide solid-state electrolytes (SSEs) offer advantages and promising prospects compared to oxide and sulfide SSEs due to their high voltage stability and interfacial compatibility with cathode materials. However, existing halide SSEs suffer from stability issues with lithium / sodium metal anodes. Therefore, when assembling all-solid-state batteries, a sulfide SSE transition layer, such as Na3PS4, is typically added between the metal anode and the halide SSE to prevent contact. While this transition layer addresses the stability issue between the halide SSE and the lithium / sodium metal anode, its thickness (typically 30–100 μm) increases the weight, volume, and cost of the all-solid-state battery. Furthermore, it significantly reduces the energy density, preventing the full realization of the advantages of all-solid-state batteries. Moreover, the added sulfide SSE transition layer and the halide SSE also present interfacial stability risks (side reactions at the interface), introducing additional interfacial impedance and reducing the performance of the all-solid-state battery. Summary of the Invention

[0005] In view of this, the primary objective of the present invention is to provide a negative electrode structure in which a uniform thin film layer with high ionic conductivity, thin thickness and certain mechanical strength is disposed between a metal negative electrode and a halide solid electrolyte layer, and is assembled with the metal negative electrode and the halide solid electrolyte into an integrated negative electrode structure. This integrated negative electrode can be directly matched with a high-voltage positive electrode material to improve the performance of all-solid-state batteries.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The present invention first provides a negative electrode structure, including a halide solid electrolyte and a metal negative electrode, wherein a thin film layer with a thickness of ≤5μm is provided between the halide solid electrolyte and the metal negative electrode;

[0008] The thin film layer is a composite sulfide film or a polymer film formed by in-situ curing. The composite sulfide film is composed of a sulfide solid electrolyte and a polymer solid electrolyte.

[0009] In a further embodiment, the thickness of the thin film layer is 0.2–5 μm.

[0010] In a further embodiment, the thickness of the thin film layer is 0.5–1.5 μm.

[0011] In a further embodiment, the sulfide solid electrolyte is Li6PS5Cl or Li 10 GeP2S 11 Li7S3P 11 Li3PS4; Na3PS4, Na 2.9 PS 3.9 Cl 0.1 A combination of one or more of Na4P2S7 and Na3SbS4.

[0012] In a further embodiment, the polymer solid electrolyte is prepared from a polymer and an electrolyte salt.

[0013] In a further embodiment, the molar ratio of the polymer to the electrolyte salt is 8:1 to 20:1.

[0014] In a further embodiment, the polymer is PEO, PVDF, CMC, PVDF-HFP, or PMMA.

[0015] In a further embodiment, the electrolyte salt is a lithium salt or a sodium salt.

[0016] In a further embodiment, the lithium salt is one or a combination of two or more of LiTFSI, LiFSI, LiPF6, LiDFOB, and LiBOB; and / or, the sodium salt is one or a combination of two or more of NaTFSI, NaFSI, NaPF6, and NaClO4.

[0017] In a further embodiment, the content of the polymer solid electrolyte in the composite sulfide film is 1 wt% to 20 wt%.

[0018] In a further embodiment, the content of the polymer solid electrolyte in the composite sulfide film is 3wt% to 10wt%.

[0019] In a further embodiment, the halide solid electrolyte is a lithium-ion halide solid electrolyte or a sodium-ion halide solid electrolyte;

[0020] And / or, the metal negative electrode is lithium metal, sodium metal, or an alloy containing lithium metal or sodium metal.

[0021] In a further embodiment, the thickness of the halide solid electrolyte is 2–20 μm.

[0022] In a further embodiment, the thickness of the halide solid electrolyte is 5–10 μm.

[0023] The present invention further provides a method for preparing the aforementioned negative electrode structure, comprising the following steps:

[0024] Form a thin film layer;

[0025] After assembling the halide solid electrolyte, thin film layer and metal anode, the anode is pressed under high pressure of 200MPa to 370MPa to form an integrated anode structure.

[0026] In a further embodiment, the thin film layer is a composite sulfide thin film.

[0027] In a further embodiment, the thin film layer is a polymer thin film, which is prepared as follows:

[0028] A prepolymer precursor solution is prepared, wherein the prepolymer precursor solution contains a polymerizable monomer, an electrolyte salt and an initiator;

[0029] The supporting membrane is placed on the metal negative electrode, the prepolymer precursor liquid is injected, and the mixture is cured in situ to obtain a polymer film.

[0030] In a further embodiment, the polymerizable monomer is at least one selected from the following: vinylene carbonate, ethylene carbonate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, glycidyl methacrylate, n-butyl acrylate, triethylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated bisphenol A dimethacrylate, polyethylene glycol dimethacrylate, acrylic acid, polyethylene glycol dimethyl ether, polyethylene glycol diglycidyl ether, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0031] And / or, the electrolyte salt is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium di(oxalate)borate, lithium di(fluorooxalate)borate, lithium difluorophosphate, lithium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium di(oxalate)borate, sodium di(fluorooxalate)borate, sodium difluorophosphate, and sodium perchlorate.

[0032] And / or, the initiator is at least one of azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, azobisisobutyronitrile cyanoformamide, azobiscyclohexylformitrile, azobisisopropylimidazoline hydrochloride, azobiscyanopentanoic acid, benzoyl peroxide, dodecyl peroxide, diisopropyl peroxide dicarbonate, and methyl ethyl ketone peroxide.

[0033] The present invention further provides an all-solid-state battery containing the negative electrode structure as described above or a negative electrode structure prepared by the preparation method as described above.

[0034] The beneficial effects of this invention are:

[0035] The integrated negative electrode structure provided in this invention utilizes a thin film layer with a thickness of ≤5μm as a transition layer, avoiding direct contact between sulfide SSE particles and the halide solid electrolyte and metal negative electrode, thereby improving interface stability and battery cycle performance. Furthermore, by not using the traditional, thicker sulfide SSE as a transition layer, the volume and weight of the all-solid-state battery are significantly reduced, resulting in a substantial increase in energy density. Moreover, this integrated negative electrode can be directly matched with high-voltage positive electrode materials, simultaneously improving battery safety. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the negative electrode structure in a preferred embodiment of the present invention.

[0037] Figure 2 The impedance test results are for the composite sulfide films prepared in Examples 1 and 7.

[0038] Figure 3 The results are the cycle performance test results of the all-solid-state battery in Example 1. Detailed Implementation

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

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0041] The first aspect of this invention provides a negative electrode structure, the simplified structural diagram of which is shown below. Figure 1 As shown, the negative electrode structure is an integrated negative electrode structure, which consists of a halide solid electrolyte, a metal negative electrode, and a thin film layer disposed between the halide solid electrolyte and the metal negative electrode.

[0042] The halide solid electrolyte described herein can be of conventional types in the art, preferably a halide solid electrolyte with high ionic conductivity to ensure the performance of the all-solid-state battery. In some specific embodiments of the present invention, the composition of the halide SSE is A. y M x B 1-x X z Where A is Li or Na, M is at least one of La, Sm, Ta, Al, Yb, Ho, and Er, B is at least one of Y, In, Sc, Zr, Er, Ti, and Hf, and X is Cl or Br; 0≤x≤1, 2≤y≤3, and z≤6. Specific examples include Li3InCl6, Li3YCl6, Li3ErCl6, Li2ZrCl6, Na2ZrCl6, and Na... 2.25 Y 0.25 Zr 0.75 Cl6, Na 0.7 La 0.7 Zr 0.3 Cl4 and NaAlCl4 are used, but the method is not limited to these. The specific thickness of the halide solid electrolyte is not particularly limited and can be within the range of the art. In some specific embodiments of the present invention, it is preferably 2–20 μm, for example, any value among 2 μm, 5 μm, 8 μm, 10 μm, 14 μm, 16 μm, 18 μm, and 20 μm. More preferably, the thickness of the halide solid electrolyte is any value among 5–10 μm.

[0043] The metal anode described in this article is selected according to the specific battery type. When preparing a lithium-ion battery, the metal anode is metallic lithium or an alloy containing metallic lithium; when preparing a sodium-ion battery, the metal anode is metallic sodium or an alloy containing metallic sodium. The specific thickness of the metal anode can adopt conventional thicknesses in the art, such as ≤10μm, preferably 5–7μm, for example, 5μm, 6μm, 7μm, etc.

[0044] The integrated negative electrode structure in this invention improves the performance of the all-solid-state battery by setting a thin film layer between the halide SSE and the metal negative electrode. This thin film layer has a uniform composition, high ionic conductivity, thin thickness, and certain mechanical strength, and can completely isolate the halide SSE and the metal negative electrode.

[0045] The thickness of the thin film layer described herein is ≤5μm, preferably between 1 and 5μm, for example, any value among 1μm, 2μm, 3μm, 4μm or 5μm.

[0046] In some embodiments, the thin film layer described herein is a composite sulfide film, which is composed of a sulfide solid electrolyte and a polymer solid electrolyte. The polymer solid electrolyte content is 1 wt% to 20 wt%, for example, any value among 1 wt%, 2 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 14 wt%, 15 wt%, 17 wt%, and 20 wt%. Preferably, the polymer solid electrolyte content is 3 wt% to 10 wt%. The sulfide solid electrolyte provides high ionic conductivity, while the polymer solid electrolyte acts as a binder and provides another portion of the ion transport pathway.

[0047] The sulfide solid electrolyte can be of conventional types in the art, preferably Li6PS5Cl or Li 10 GeP2S 11 Li7S3P 11 Li3PS4; Na3PS4, Na 2.9 PS 3.9 Cl 0.1 It can be one or more of Na4P2S7 and Na3SbS4, but is not limited to these. The specific choice can be made according to the type of battery and actual needs.

[0048] The polymer solid electrolyte is prepared from a polymer and an electrolyte salt. Specifically, the polymer can be PEO, PVDF, CMC, PVDF-HFP, or PMMA. The electrolyte salt can be a lithium salt or a sodium salt, depending on the type of battery. In some specific embodiments of the present invention, the electrolyte salt is a lithium salt, such as one or more of LiTFSI, LiFSI, LiPF6, LiDFOB, and LiBOB. In other specific embodiments of the present invention, the electrolyte salt is a sodium salt, such as one or more of NaTFSI, NaFSI, NaPF6, and NaClO4. However, the invention is not limited to these embodiments.

[0049] In some specific embodiments of the present invention, the molar ratio of the polymer to the electrolyte salt is 8:1 to 20:1, for example, any ratio among 8:1, 9:1, 10:1, 12:1, 15:1, 16:1, 18:1, and 20:1, preferably 20:1.

[0050] In other embodiments, the thin film layer described herein is a polymer thin film formed by in-situ curing, which is formed by injecting a prepolymer precursor liquid into the contact surface between the support film and the metal negative electrode, and then performing an in-situ curing reaction.

[0051] A second aspect of the present invention provides a method for preparing a negative electrode structure as described in the first aspect of the present invention, comprising the following steps:

[0052] Form a thin film layer;

[0053] After assembling the halide solid electrolyte, thin film layer and metal anode, the anode is pressed under high pressure of 200MPa to 370MPa to form an integrated anode structure.

[0054] In some specific embodiments of the present invention, the thin film layer is a composite sulfide thin film, which is specifically prepared by mixing a sulfide solid electrolyte and a polymer solid electrolyte and then casting. Preferably, the sulfide solid electrolyte is prepared by high-energy ball milling.

[0055] In other specific embodiments of the present invention, the thin film layer is a polymer thin film, which can be formed by in-situ curing through methods such as casting or spin coating. In some specific embodiments of the present invention, its preparation includes the following steps:

[0056] A prepolymer precursor solution is prepared, wherein the prepolymer precursor solution contains a polymerizable monomer, an electrolyte salt and an initiator;

[0057] The support film is placed on the metal negative electrode, the prepolymer precursor liquid is injected, and the polymer film is cured in situ.

[0058] The polymerizable monomer may be at least one of the following: vinylene carbonate, ethylene carbonate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, glycidyl methacrylate, n-butyl acrylate, triethylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated bisphenol A dimethacrylate, polyethylene glycol dimethacrylate, acrylic acid, polyethylene glycol dimethyl ether, polyethylene glycol diglycidyl ether, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0059] Furthermore, the electrolyte salt is a conventional lithium or sodium salt commonly used in the art, specifically including at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium dioxalateborate, lithium difluorooxalateborate, lithium difluorophosphate, lithium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium dioxalateborate, sodium difluorooxalateborate, sodium difluorophosphate, and sodium perchlorate, but not limited to these. The specific type can be selected according to the type of battery, etc., and the specific concentration can be a conventional concentration in the art, such as 0.2–3.0 mol / L.

[0060] Furthermore, the initiator can be adapted according to the specific type of polymerizable monomer. Specific examples include at least one of azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, azobisisobutyronitrile cyanoformamide, azobiscyclohexylformitrile, azobisisopropylimidazoline hydrochloride, azobiscyanopentanoic acid, benzoyl peroxide, dodecyl peroxide, diisopropyl peroxide dicarbonate, and methyl ethyl ketone peroxide, but are not limited to these. The amount of initiator added can be selected according to actual needs, preferably from 0.1 wt% to 10 wt%.

[0061] Furthermore, it is understandable that most polymerizable monomers can act as solvents themselves. Additional solvents, such as EC, PC, EMC, DEC, DMC, VC, or FEC, can be added as needed. These additional solvents can also act as plasticizers, further enhancing the performance of the film layer.

[0062] It is understood that the preparation of the thin film layer in this invention is not limited to the preparation method described above. Any method in the art that can prepare the thin film layer in this invention is applicable to the preparation of the negative electrode structure in this invention.

[0063] A third aspect of the present invention provides an all-solid-state battery comprising a negative electrode structure as described in the first aspect of the present invention or a negative electrode structure prepared by the preparation method described in the first aspect of the present invention.

[0064] It is understandable that the cathode and other materials in all-solid-state batteries can adopt conventional compositions in this field, which will not be elaborated here.

[0065] The present invention will be described below through specific embodiments. It should be noted that the specific embodiments below are for illustrative purposes only and do not limit the scope of the present invention in any way. In addition, unless otherwise specified, methods that do not specifically describe conditions or steps are conventional methods, and the reagents and materials used can be obtained commercially.

[0066] Example 1

[0067] This embodiment provides a negative electrode structure with a composite sulfide thin film as the thin film layer and the fabrication of an all-solid-state battery based on this negative electrode structure. The specific steps are as follows:

[0068] 1. Preparation of composite sulfide thin films Na3PS4-PEO-NaTFSI

[0069] Sodium sulfide (Na2S) and phosphorus pentasulfide (P2S5) were sealed in a zirconium oxide (ZrO2) ball mill jar in an inert atmosphere at a molar ratio of 3:1 and ball-milled in a planetary ball mill at a speed of 500 rpm for 10 h, followed by annealing at 270 °C for 1 h to obtain Na3PS4.

[0070] 970 mg Na3PS4 and 30 mg PEO-NaTFSI (EO / Na = 20:1 molar ratio) were added to acetonitrile solvent (ACN), stirred at 60 °C for 24 h, and then cast into a film by casting method. After drying at 80 °C for 2 h, a Na3PS4-PEO-NaTFSI (3wt%) composite sulfide film with a thickness of 3 μm was finally prepared by hot pressing at 200 °C.

[0071] 2. Assemble all-solid-state batteries

[0072] Positive electrode: The positive electrode active material sodium vanadium phosphate (Na3V2(PO4)3) is reacted with Na... 0.7 La 0.7 Zr 0.3 Cl4 (NLZC) and conductive agent SP were mixed in a mass ratio of 50:50:3, and then ball-milled in a planetary ball mill at 200 rpm for 30 min using a stainless steel ball mill jar to obtain positive electrode powder, which was then pressed to obtain a composite positive electrode.

[0073] Negative electrode: Sodium and tin are mixed in a stainless steel ball mill jar at a molar ratio of 2:1 and ball milled in a planetary ball mill at a speed of 300 rpm for 20 hours to obtain a sodium-tin alloy, which is then pressed to obtain the negative electrode.

[0074] Halides (SSE): In an inert atmosphere, sodium chloride (NaCl), lanthanum chloride (LaCl3), and zirconium chloride (ZrCl4) were mixed in a molar ratio of 0.7:07:0.3, then sealed in a zirconium oxide (ZrO2) ball mill jar and ball-milled at 550 rpm for 10 h in a planetary ball mill to obtain Na... 0.7 La 0.7 Zr 0.3 Cl4 precursor; the precursor was annealed at 400℃ for 2 h and then ball-milled again for 5-10 h to obtain halide SSE, Na 0.7 La 0.7 Zr 0.3 Cl4.

[0075] The halide SSE, composite sulfide film and metal anode are assembled in a 12 mm diameter polytetrafluoroethylene mold and held under a pressure of 370 MPa for 10 min to form an integrated anode structure; the integrated anode structure and composite cathode are then loaded into the mold under a pressure of 370 MPa to form an all-solid-state battery.

[0076] Example 2

[0077] In this embodiment, the negative electrode structure is prepared using the same method as in Example 1, except that the polymer solid electrolyte in the composite sulfide film is PVDF-HFP-NaTFSI. Other process conditions and the preparation of the all-solid-state battery are the same as in Example 1.

[0078] Example 3

[0079] In this embodiment, the negative electrode structure is prepared using the same method as in Example 1, except that the polymer solid electrolyte in the composite sulfide film is PEO-NaFSI. Other process conditions and the preparation of the all-solid-state battery are the same as in Example 1.

[0080] Example 4

[0081] In this embodiment, the negative electrode structure is prepared using the same method as in Example 1, the only difference being that the sulfide solid electrolyte in the composite sulfide film is Na. 2.9 PS 3.9 Cl 0.1 Other process conditions and the preparation of the all-solid-state battery are the same as in Example 1.

[0082] Example 5

[0083] In this embodiment, the negative electrode structure is prepared using the same method as in Example 1, except that the content of the polymer solid electrolyte in the composite sulfide film is 10 wt%. Other process conditions and the preparation of the all-solid-state battery are the same as in Example 1.

[0084] Example 6

[0085] In this embodiment, the negative electrode structure is prepared using the same method as in Example 1, except that the content of the polymer solid electrolyte in the composite sulfide film is 5 wt%. Other process conditions and the preparation of the all-solid-state battery are the same as in Example 1.

[0086] Example 7

[0087] The composite sulfide film in this embodiment is prepared as follows:

[0088] 1. Preparation of composite sulfide thin films Li6PS5Cl-PEO-LiTFSI

[0089] In an inert atmosphere, lithium chloride (LiCl), lithium sulfide (Li2S), and phosphorus pentasulfide (P2S5) were sealed in a zirconium oxide (ZrO2) ball mill jar and ball-milled in a planetary ball mill at 500 rpm for 20 hours, followed by annealing at 500°C for 10 hours to obtain Li6PS5Cl.

[0090] 950 mg Li6PS5Cl and 50 mg PEO-LiTFSI (EO / Na = 20:1 molar ratio) were added to acetonitrile solvent (ACN), stirred at 60 °C for 24 h, and then cast into a film by casting method. After drying at 80 °C for 2 h, a Li6PS5Cl-PEO-LiTFSI (5wt%) composite sulfide film with a thickness of 5 μm was finally prepared by hot pressing at 200 °C.

[0091] 2. Assemble all-solid-state batteries

[0092] Positive electrode: The positive electrode active material lithium cobalt oxide (LiCoO2) is mixed with the halide Li3InCl6 and the conductive agent SP at a mass ratio of 70:30:1. Then, the mixture is ball-milled in a planetary ball mill at a speed of 200 rpm for 30 minutes using a stainless steel ball mill jar to obtain positive electrode powder, which is then pressed to obtain a composite positive electrode.

[0093] Negative electrode: Lithium metal and tin metal are mixed in a stainless steel ball mill jar at a molar ratio of 2:1 and ball milled in a planetary ball mill at a speed of 300 rpm for 20 hours to obtain a lithium-tin alloy, which is then pressed to obtain the negative electrode.

[0094] Lithium chloride (LiCl) and indium chloride (InCl3) were mixed in a 3:1 molar ratio in an inert atmosphere, and then sealed in a zirconium oxide (ZrO2) ball mill jar and ball milled in a planetary ball mill at 550 rpm for 10 h to obtain Li3InCl6 halide SSE.

[0095] The halide SSE, a 5μm Li6PS5Cl-PEO-LiTFSI composite sulfide film, and a metal anode were assembled in a 12mm diameter polytetrafluoroethylene mold and held under a pressure of 370MPa for 10 minutes to form an integrated anode. The integrated anode and the composite cathode were then sequentially loaded into the mold under a pressure of 370MPa to assemble an all-solid-state battery.

[0096] Example 8

[0097] This embodiment provides a negative electrode structure with a polymer thin film layer and the fabrication of an all-solid-state battery based on this negative electrode structure. The specific steps are as follows:

[0098] 1. Preparation of prepolymer precursor solution:

[0099] The liquid organic solvent vinylene carbonate, the electrolyte salt sodium hexafluorophosphate, the initiator azobisisobutyronitrile, the additive succinic acid nitrile, and the functional additive N-methyl-N-(trimethylsilyl)trifluoroacetamide are thoroughly mixed and stirred to obtain the prepolymer precursor solution.

[0100] The concentration of sodium hexafluorophosphate was 1 mol / L, based on liquid organic solvents; the content of azobisisobutyronitrile was 2 wt%; the content of succinic anionyl nitrile was 10 wt%; and the content of N-methyl-N-(trimethylsilyl)trifluoroacetamide was 2 wt%.

[0101] 2. Preparation of integrated negative electrode

[0102] According to the liquid lithium battery assembly method, in an argon-protected glove box, a glass fiber separator is placed on a sodium metal negative electrode, a prepolymer precursor liquid is injected, and the mixture is heated at 55°C for 12 hours to form a GPE polymer film with a thickness of 5 μm.

[0103] After assembling the halide SSE, gel polymer film, and sodium metal anode, the integrated anode was obtained by maintaining it under a pressure of 370 MPa for 10 min.

[0104] 3. Assemble all-solid-state batteries

[0105] After assembling the composite positive electrode and the integrated negative electrode, they are assembled into an all-solid-state battery under a pressure of 370 MPa.

[0106] The composition of the composite cathode, halide SSE, and metal anode in this all-solid-state battery is the same as in Example 1.

[0107] Example 9

[0108] In this embodiment, the negative electrode structure is prepared using the same method as in Example 8, except that the initiator in the polymer film is azobisisovalerate. Other process conditions and the preparation of the all-solid-state battery are the same as in Example 8.

[0109] Example 10

[0110] In this embodiment, the negative electrode structure is prepared using the same method as in Example 8, except that the electrolyte salt in the polymer film is lithium hexafluorophosphate, and the negative electrode is a lithium metal negative electrode.

[0111] The obtained negative electrode structure was combined with a halide Li3InCl6 and a lithium cobalt oxide positive electrode to form an all-solid-state battery. The preparation of the halide Li3InCl6 and the lithium cobalt oxide positive electrode was the same as in Example 7.

[0112] Comparative Example 1

[0113] In this comparative example, the all-solid-state battery was prepared using the same method as in Example 1, except that the composite sulfide film in Example 1 was replaced with a sulfide Na3PS4 with a thickness of 50 μm.

[0114] Performance testing

[0115] The all-solid-state batteries prepared in the examples and comparative examples were cycled at 30°C for 70 cycles to test their electrochemical performance. The test results are shown in Table 1.

[0116] Table 1 Performance Tests of All-Solid-State Batteries

[0117] cathode materials First-cycle discharge specific capacity Volume retention rate after 70 laps Example 1 NVP 115mAh / g 88％ Example 2 NVP 110mAh / g 85％ Example 3 NVP 111mAh / g 87％ Example 4 NVP 105mAh / g 90％ Example 5 NVP 115mAh / g 95％ Example 6 NVP 108mAh / g 92％ Example 7 LCO 140mAh / g 90％ Example 8 NVP 115mAh / g 90％ Example 9 NVP 101mAh / g 95％ Example 10 LCO 180mAh / g 84％ Comparative Example 1 NVP 110mAh / g 80％

[0118] As can be seen from the test results in Table 1, the all-solid-state battery prepared using the integrated negative electrode of this invention exhibits excellent electrochemical performance. Specifically, the battery in Example 10, when charged to 4.5V, achieved a first-cycle discharge specific capacity of 180 mAh / g, demonstrating that the integrated negative electrode of this invention can be directly matched with a high-voltage positive electrode, exhibiting superior performance.

[0119] also, Figure 2 The impedance test results of the composite sulfide films prepared in Examples 1 and 7 are shown, which are 330Ω and 342Ω, respectively. Figure 3 The cycle performance test results of the all-solid-state battery in Example 1 are shown. After 70 cycles, the full battery had a discharge capacity of 102 mAh / g and a capacity retention of 88%.

[0120] The above embodiments demonstrate that the integrated negative electrode structure of the present invention avoids the use of a sulfide SSE transition layer, resulting in low interfacial impedance between interfaces. The assembled all-solid-state battery has high energy density and excellent cycle performance, and can be directly matched with a high-voltage positive electrode.

[0121] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A negative electrode structure, characterized in that, It includes a halide solid electrolyte and a metal anode, with a thin film layer of ≤5μm thickness disposed between the halide solid electrolyte and the metal anode; The thin film layer is a composite sulfide film or a polymer film formed by in-situ curing. The composite sulfide film is composed of a sulfide solid electrolyte and a polymer solid electrolyte. The polymer film is prepared as follows: A prepolymer precursor solution is prepared, wherein the prepolymer precursor solution contains a polymerizable monomer, an electrolyte salt and an initiator; The supporting membrane is placed on the metal negative electrode, the prepolymer precursor liquid is injected, and the mixture is cured in situ to obtain a polymer film.

2. The negative electrode structure as described in claim 1, characterized in that, The thickness of the thin film layer is 0.2~5μm.

3. The negative electrode structure as described in claim 2, characterized in that, The thickness of the thin film layer is 0.5~1.5μm.

4. The negative electrode structure as described in claim 1, characterized in that, The sulfide solid electrolyte is Li6PS5Cl or Li7S3P 11 Li3PS4, Li 10 GeP2S 11 Na3PS4, Na 2.9 PS 3.9 Cl 0.1 A combination of one or more of Na4P2S7 and Na3SbS4.

5. The negative electrode structure as described in claim 1, characterized in that, The content of polymer solid electrolyte in the composite sulfide film is 1wt%~20wt%.

6. The negative electrode structure as described in claim 5, characterized in that, The content of polymer solid electrolyte in the composite sulfide film is 3wt%~10wt%.

7. The negative electrode structure as described in claim 1, characterized in that, The polymer solid electrolyte is prepared from a polymer and an electrolyte salt.

8. The negative electrode structure as described in claim 7, characterized in that, The molar ratio of the polymer to the electrolyte salt is 8:1 to 20:

1.

9. The negative electrode structure as described in claim 7, characterized in that, The polymer is PEO, PVDF, CMC, PVDF-HFP, or PMMA.

10. The negative electrode structure as described in claim 7, characterized in that, The electrolyte salt is a lithium salt or a sodium salt.

11. The negative electrode structure as described in claim 10, characterized in that, The lithium salt is one or a combination of two or more of LiTFSI, LiFSI, LiPF6, LiDFOB, and LiBOB; and / or, the sodium salt is one or a combination of two or more of NaTFSI, NaFSI, NaPF6, and NaClO4.

12. The negative electrode structure as described in claim 1, characterized in that, The halide solid electrolyte is a lithium-ion halide solid electrolyte or a sodium-ion halide solid electrolyte; And / or, the metal negative electrode is lithium metal, sodium metal, or an alloy containing lithium metal or sodium metal.

13. The negative electrode structure as described in claim 12, characterized in that, The thickness of the halide solid electrolyte is 2~20 μm.

14. The negative electrode structure as described in claim 12, characterized in that, The thickness of the halide solid electrolyte is 5~10 μm.

15. A method for preparing the negative electrode structure according to any one of claims 1-14, characterized in that, Includes the following steps: Form a thin film layer; After assembling the halide solid electrolyte, thin film layer and metal anode, the anode is pressed under high pressure of 200MPa~370MPa to form an integrated anode structure.

16. The preparation method according to claim 15, characterized in that, The thin film layer is a composite sulfide thin film.

17. The preparation method according to claim 15, characterized in that, The thin film layer is a polymer thin film, which is prepared as follows: A prepolymer precursor solution is prepared, wherein the prepolymer precursor solution contains a polymerizable monomer, an electrolyte salt and an initiator; The supporting membrane is placed on the metal negative electrode, the prepolymer precursor liquid is injected, and the mixture is cured in situ to obtain a polymer film.

18. The preparation method according to claim 17, characterized in that, The polymerizable monomer is at least one of the following: vinylene carbonate, ethylene carbonate, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, glycidyl methacrylate, n-butyl acrylate, triethylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated bisphenol A dimethacrylate, polyethylene glycol dimethacrylate, acrylic acid, polyethylene glycol diglycidyl ether, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate. And / or, the electrolyte salt is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium di(oxalate)borate, lithium di(fluorooxalate)borate, lithium difluorophosphate, lithium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium trifluoromethanesulfonate, sodium bis(trifluoromethanesulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium di(oxalate)borate, sodium di(fluorooxalate)borate, sodium difluorophosphate, and sodium perchlorate. And / or, the initiator is at least one of azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, azobisisobutyronitrile cyanoformamide, azobiscyclohexylformitrile, azobisisopropylimidazoline hydrochloride, azobiscyanopentanoic acid, benzoyl peroxide, dodecyl peroxide, diisopropyl peroxide dicarbonate, and methyl ethyl ketone peroxide.

19. An all-solid-state battery, characterized in that, It contains the negative electrode structure as described in any one of claims 1-14 or the negative electrode structure prepared by the preparation method as described in any one of claims 15-18.

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