Solid-state battery cell, negative electrode sheet, and positive electrode sheet, and methods of making the same, related devices

Abstract

The application relates to the technical field of batteries, in particular to a solid-state battery monomer, a negative electrode sheet and a positive electrode sheet and preparation methods therefor and related devices. The solid-state battery monomer comprises a negative electrode sheet and a positive electrode sheet; the negative electrode sheet comprises a first binder, the first binder comprising a structural unit or a tautomer thereof; and / or the positive electrode sheet comprises a second binder, the second binder comprising a structural unit or a tautomer thereof; and the application can effectively improve the cycle performance of the solid-state battery at a high rate.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to solid-state battery cells, negative electrode sheets and positive electrode sheets, their preparation methods and related apparatus. Background Technology

[0002] Commercial lithium-ion batteries typically use electrolytes containing flammable carbonate and ether solvents. These electrolytes can easily cause lithium-ion batteries to spontaneously combust or explode under conditions such as impact or puncture, posing a significant safety hazard. In contrast, solid-state batteries, especially all-solid-state batteries, using solid-state electrolytes, can effectively solve the safety issues during battery use. However, in practice, it is often found that the rate performance of solid-state batteries cannot match that of liquid batteries, particularly their poor cycle performance at higher rates. Summary of the Invention

[0003] This application is made in view of the above-mentioned technical problems, and its purpose is to solve the problem of insufficient cycle performance of solid-state batteries at high rates.

[0004] To achieve the above objectives, this application provides a solid-state battery cell, a negative electrode sheet and a positive electrode sheet, a method for preparing the same and related apparatus.

[0005] The first aspect of this application provides a solid-state battery cell, including a negative electrode and a positive electrode;

[0006] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector. The negative electrode active layer includes a negative electrode active material and a first binder.

[0007] The positive electrode sheet includes a positive current collector and a positive active layer disposed on at least one side of the positive current collector, the positive active layer including a positive active material and a second binder;

[0008] Solid-state battery cells must satisfy one or both of the following conditions 1) and 2):

[0009] 1) The first binder comprises the structural unit shown in Formula I or its tautomer;

[0010] 2) The second binder comprises the structural unit shown in Formula I or its tautomer;

[0011]

[0012] Formula I, n=10000~100000.

[0013] In this embodiment, a substance comprising the structural unit shown in Formula I or its tautomer is used as a binder in the electrode (negative electrode or positive electrode), which can effectively improve the cycle performance of solid-state batteries at high rates. The mechanism includes:

[0014] The material containing the structural unit shown in Formula I or its tautomer has high viscosity and can be used as a binder. The conjugated structure in the structural unit can provide a fast ion / electron transport channel between the active material particles of the electrode, so that the electrode exhibits low resistance and high ion / electron transport capability, thereby improving the cycle performance of solid-state batteries at high rates.

[0015] In some embodiments, the first binder has a mass content of 2% to 9% in the negative electrode active layer, optionally 3% to 5%. The second binder has a mass content of 2% to 9% in the positive electrode active layer, optionally 3% to 5%.

[0016] At this binder content (either the first or second binder), the ion / electron transport performance of the electrode can be effectively improved, enhancing the cycle performance of solid-state batteries at high rates. Furthermore, with a binder content of 3%–5% by mass, the binder exhibits excellent uniformity within the electrode active layer, resulting in a smooth electrode and better performance of the solid-state battery. Additionally, at this mass content, the binder does not excessively occupy the proportion of electrode active material used to provide capacity, which is beneficial for improving the energy density of the electrode.

[0017] In some embodiments, the first binder comprises a cyclized PAN (cyclized polyacrylonitrile) polymer. The second binder comprises a cyclized PAN polymer.

[0018] Cyclic PAN polymers have high ion / electron transport capabilities, which are beneficial to improving the ion / electron transport performance of electrodes. In addition, cyclic PAN polymers have high viscosity, which can improve the cohesion of electrodes. Under the combined effect, they can effectively improve the cycle performance of solid-state batteries at high rates.

[0019] A second aspect of this application provides a negative electrode sheet, including a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector. The negative electrode active layer includes a negative electrode active material and a first binder. The first binder includes a structural unit of Formula I or a tautomer thereof.

[0020]

[0021] Formula I, n=10000~100000.

[0022] A third aspect of this application provides a positive electrode sheet, including a positive current collector and a positive active layer disposed on at least one side of the positive current collector. The positive active layer includes a positive active material and a second binder. The second binder includes a structural unit of Formula I or a tautomer thereof.

[0023]

[0024] Formula I, n=10000~100000.

[0025] The fourth aspect of this application provides a method for preparing a negative electrode sheet, comprising:

[0026] A negative electrode active layer comprising a negative electrode active material and a first binder precursor is prepared on at least one side of the negative electrode current collector. The first binder precursor includes the structural unit shown in Formula II.

[0027] This causes the first adhesive precursor to undergo a cross-linking reaction;

[0028]

[0029] Formula II, n = 10000 ~ 100000.

[0030] The first adhesive precursor includes the structural unit shown in Formula II. The crosslinking reaction of the first adhesive precursor includes intermolecular crosslinking and intramolecular cyclization (therefore, the crosslinking reaction of the first adhesive precursor can also be described as the cyclization reaction of the first adhesive precursor), generating a first adhesive containing the structural unit shown in Formula I or its tautomer.

[0031] The preparation method of this application embodiment can form a first binder containing the structural unit shown in Formula I or the structural unit shown in its tautomer in the negative electrode active layer. The conjugated structure in the structural unit shown in Formula I or its tautomer can provide a fast ion / electron transport channel between the negative electrode active material particles, so that the negative electrode sheet exhibits low resistance and high ion / electron transport capability, thereby improving the cycle performance of solid-state batteries at high rates.

[0032] In some embodiments, the mass content of the first binder precursor in the negative electrode active layer is 3% to 10%, optionally 4% to 6%.

[0033] At this content, a certain amount of a first binder precursor, comprising the structural unit shown in Formula I or its tautomers, with high ion / electron transport performance, can be generated using the first binder precursor. This gives the negative electrode sheet suitable conductivity, which is beneficial for improving the cycle performance of solid-state batteries at high rates. Furthermore, when the mass content of the first binder precursor in the negative electrode active layer is 4% to 6%, both the first binder precursor and the generated first binder have good uniformity in the negative electrode active layer, which can enable the solid-state battery to exhibit better performance.

[0034] In some embodiments, the first binder precursor includes a PAN-based polymer. Cyclic PAN-based polymers have high ion / electron transport capabilities, which is beneficial for improving the ion / electron transport performance of the negative electrode. Furthermore, cyclized PAN-based polymers have high viscosity, which can improve the cohesion of the negative electrode sheet. The combined effect can effectively improve the cycle performance of solid-state batteries at high rates.

[0035] In some embodiments, the method for causing the first binder precursor to undergo a crosslinking reaction includes: performing heat treatment under a protective atmosphere. The heat treatment temperature is 200°C to 350°C, optionally 280°C to 320°C. The heat treatment time is 4 hours to 9 hours, optionally 4 hours to 6 hours.

[0036] Heat treatment under a protective atmosphere allows the first binder precursor, comprising the structural unit shown in Formula II, to undergo intermolecular and intramolecular crosslinking, generating a first binder comprising the structural unit shown in Formula I or its tautomers. The conjugated structure in the structural unit shown in Formula I or its tautomers can provide rapid ion / electron transport channels between the negative electrode active material particles, which is beneficial for improving the cycle performance of solid-state batteries at high rates. Furthermore, by controlling the temperature and time of the heat treatment, the generated first binder can have a suitable degree of cyclization, which can both improve the cohesion of the negative electrode and give the negative electrode suitable conductivity. When the negative electrode is applied to a solid-state battery, it can have good compatibility with most solid electrolyte membranes in the solid-state battery, mitigating the phenomenon of solid electrolyte membrane decomposition caused by excessive conductivity.

[0037] The fifth aspect of this application provides a method for preparing a positive electrode sheet, comprising:

[0038] A positive electrode active layer comprising a positive electrode active material and a second binder precursor is prepared on at least one side of the positive electrode current collector. The second binder precursor includes the structural unit shown in Formula II.

[0039] The second adhesive precursor undergoes a cross-linking reaction;

[0040]

[0041] Formula II, n = 10000 ~ 100000.

[0042] The preparation method of this application embodiment can form a second binder containing the structural unit shown in Formula I or its tautomer in the positive electrode active layer. The conjugated structure in the structural unit shown in Formula I or its tautomer can provide a fast ion / electron transport channel between the positive electrode active material particles, so that the positive electrode sheet exhibits low resistance and high ion / electron transport capability, thereby improving the cycle performance of solid-state batteries at high rates.

[0043] This application also provides some related devices, including battery devices, energy storage devices, and power consumption devices.

[0044] The battery device includes multiple solid-state battery cells.

[0045] The solid-state battery cell of this application embodiment has good cycle performance. Therefore, applying the solid-state battery cell to a battery device can help improve the cycle performance of the battery device and extend the service life of the battery device.

[0046] Energy storage devices include multiple solid-state battery cells or multiple battery devices, which are used to store or provide electrical energy.

[0047] The aforementioned solid-state battery cells and battery devices with good cycle performance are used to store or provide electrical energy for energy storage devices, which can extend the service life of energy storage devices.

[0048] Electrical devices include multiple solid-state battery cells or multiple battery devices, which are used to store or provide electrical energy.

[0049] The aforementioned solid-state battery cells and battery devices with good cycle performance can be used as power sources for electrical devices or as energy storage units for electrical devices, thereby extending the service life of electrical devices. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram illustrating the fabrication of the negative electrode sheet in an embodiment of this application;

[0052] Figure 2 This is a schematic diagram of a solid-state battery cell according to one embodiment of this application;

[0053] Figure 3 for Figure 2 An exploded view of a solid-state battery cell according to an embodiment of this application is shown. Detailed Implementation

[0054] The embodiments of this application are hereby disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0055] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0056] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0057] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0058] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0059] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0060] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0061] Commercial lithium-ion batteries typically use electrolytes containing flammable carbonate and ether solvents. These electrolytes can easily cause lithium-ion batteries to spontaneously combust or explode under conditions such as impact or puncture, posing a significant safety hazard. In contrast, solid-state batteries using solid-state electrolytes, especially all-solid-state batteries, can effectively solve the safety issues during battery use.

[0062] However, in practice, it is often found that the rate performance of solid-state batteries is difficult to match that of liquid-state batteries. This may be due to several reasons, including the fact that existing electrodes typically use non-ionic / electronic active materials such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) as binders. These binders can hinder ion / electron transport within the electrode. This hindering effect is particularly pronounced in all-solid-state batteries due to the non-flowability of the solid electrolyte. Ultimately, this makes it difficult for solid-state batteries to achieve good rate performance, such as poor cycle performance at high rates.

[0063] Based on this, this application provides a solid-state battery cell in which a special polymer is used as a binder in the electrode to reduce the obstruction of ion / electron transport by the binder, so that the solid-state battery can also exhibit good cycle performance at high rates.

[0064] Specifically, the solid-state battery cell in this application embodiment includes a negative electrode and a positive electrode;

[0065] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector. The negative electrode active layer includes a negative electrode active material and a first binder.

[0066] The positive electrode sheet includes a positive current collector and a positive active layer disposed on at least one side of the positive current collector, the positive active layer including a positive active material and a second binder;

[0067] Solid-state battery cells must satisfy one or both of the following conditions 1) and 2):

[0068] 1) The first binder comprises the structural unit shown in Formula I or its tautomer;

[0069] 2) The second binder comprises the structural unit shown in Formula I or its tautomer;

[0070]

[0071] Formula I, n=10000~100000.

[0072] For example, n can be any point value from 10000, 20000, 40000, 60000, 80000, 100000, or a range between any two.

[0073] In Formula I, the tautomers refer to functional group isomers resulting from double bond or proton migration. For example, possible tautomers of the structural unit shown in Formula I are shown in Formulas I-1 and I-2. Infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) techniques can be used to test the active layer of the electrode (positive or negative electrode) to determine its composition and whether it contains the structural unit shown in Formula I or its tautomers. For example, the infrared spectrum of the structural unit shown in Formula I typically has a peak at 1620 cm⁻¹. -1 Nearby (C=N stretching vibration peak), 2940cm -1 An absorption peak appears nearby (CH2 stretching vibration). 13 In C NMR spectra, a resonance peak typically appears at 155 ppm (C=N). Understandably, the positions of these absorption or resonance peaks are merely examples. Due to the diversity of binder forms and the different chemical environments in which the binder exists, the positions of the absorption or resonance peaks in their infrared and NMR spectra may vary. The peak positions of the structural units shown in Formula I can be determined based on the specific circumstances and in conjunction with common chemical analysis methods.

[0074]

[0075] Formula I-1 Formula I-2.

[0076] In this embodiment, the electrode uses a substance comprising the structural unit shown in Formula I or its tautomer as a binder, which can effectively improve the cycle performance of solid-state batteries at high rates. The mechanism includes:

[0077] The material containing the structural unit shown in Formula I or its tautomer has high viscosity and can be used as a binder. The conjugated structure in the structural unit can provide a fast ion / electron transport channel between the active material particles of the electrode, so that the electrode exhibits low resistance and high ion / electron transport capability, thereby improving the cycle performance of solid-state batteries at high rates.

[0078] [Negative electrode plate]

[0079] When the solid-state battery cell satisfies condition 1), that is, when the first binder includes the structural unit shown in Formula I or its tautomer, the negative electrode sheet of the present application embodiment has the following characteristics.

[0080] In some embodiments, the mass content of the first binder in the negative electrode active layer is 2% to 9%, optionally 3% to 5%, for example, any value or range between 2%, 3%, 4%, 5%, 6%, 7%, 8%, and 9%. Since the thermal decomposition temperature of the first binder differs from that of the negative electrode active material and other substances in the negative electrode active layer, the mass content of the first binder in the negative electrode active layer can be determined using thermogravimetric analysis. At this first binder content, the ion / electron transport performance of the negative electrode sheet can be effectively improved, enhancing the cycle performance of the solid-state battery at high rates. Furthermore, with a first binder mass content of 3% to 5%, the first binder exhibits good uniformity in the negative electrode active layer, resulting in a flat negative electrode sheet and better performance of the solid-state battery. Additionally, at this mass content, the first binder does not excessively occupy the proportion of the negative electrode active material used to provide capacity, which is beneficial for improving the energy density of the negative electrode sheet.

[0081] In some embodiments, the first binder comprises a cyclized PAN (cyclized polyacrylonitrile) polymer.

[0082] Cyclic PAN polymers are polymers containing a cyclized PAN structure. Cyclic PAN is a product generated by the cyclization reaction of PAN polymers (PAN polymers are polymers containing a PAN structure, which can be PAN itself or PAN with added substituents or other molecular segments, containing the structural unit shown in Formula II). Depending on the cyclization conditions, cyclized PAN may have different structural formulas. It is generally believed that cyclized PAN contains the structural unit shown in Formula I or its tautomers, and may contain the structural unit shown in Formula III. Cyclic PAN polymers are polymers containing a cyclized PAN structure, and therefore also contain the structural unit shown in Formula II. Cyclic PAN polymers can be cyclized PAN, or they can be cyclized PAN with added substituents or other molecular segments.

[0083]

[0084] Formula II and Formula III.

[0085] Infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) techniques can be used to test the negative electrode active layer to determine its composition and whether it contains cyclic PAN polymers. For example, the infrared spectra of cyclic PAN polymers typically show a peak at 1620 cm⁻¹. -1 Nearby (C=N stretching vibration peak), 2243cm -1 An absorption peak appears near the C≡N stretching vibration peak, possibly at 1580 cm⁻¹. -1 There is an absorption peak nearby (C=C stretching vibration peak, some cyclized PAN structures may contain C=C bonds); 13 In C NMR spectra, resonance peaks typically appear around 155 ppm (C=N) and 108 ppm (uncyclized C≡N), and may appear around 116 ppm (C=C) and 150 ppm (C=C). Understandably, these absorption or resonance peak positions are merely examples. Due to the diversity of cyclized PAN polymer structures and the different chemical environments in which they exist, the positions of absorption or resonance peaks in their infrared and NMR spectra may vary. The peak positions of cyclized PAN can be determined based on the specific circumstances and in conjunction with common chemical analysis methods.

[0086] Cyclic PAN polymers have high ion / electron transport capabilities, which are beneficial to improving the ion / electron transport performance of the negative electrode. In addition, cyclic PAN polymers have high viscosity, which can improve the cohesion of the negative electrode sheet. Under the combined effect, they can effectively improve the cycle performance of solid-state batteries at high rates.

[0087] In some embodiments, the thickness of the negative electrode active layer is 10 μm to 30 μm, for example, any one of 10 μm, 15 μm, 20 μm, 25 μm, 30 μm or a range between any two.

[0088] The thickness of the negative electrode active layer in this application embodiment can be designed as needed and is not limited to the thickness range listed above. For negative electrode active layers of different thicknesses, the solutions adopted in this application embodiment can improve the cycle performance of solid-state batteries at high rates.

[0089] In some embodiments, the negative electrode active material includes one or more of silicon-based materials, graphite (artificial graphite, natural graphite), mesophase carbon microspheres, soft carbon, hard carbon, and tin-based materials, optionally including silicon-based materials. Silicon-based materials may include one or more of elemental silicon, silicon-oxygen materials (compounds or composites containing silicon and oxygen), silicon-carbon materials (compounds or composites containing silicon and carbon), silicon-nitrogen materials (compounds or composites containing silicon and nitrogen), and silicon alloys. Tin-based materials may include one or more of elemental tin, tin-oxygen materials, and tin alloys.

[0090] Understandably, this application is not limited to these materials, and other materials that can be used as battery negative electrode active materials can also be used. The first binder containing the structural unit shown in Formula I or its tautomer is usually obtained by cyclizing the corresponding first binder precursor at high temperature. Therefore, a negative electrode active material with high stability that does not react with other substances (e.g., the first binder precursor) during the preparation of the negative electrode sheet can usually be selected, thereby reducing the difficulty in forming the negative electrode sheet and successfully obtaining the desired negative electrode sheet. Typically, the negative electrode active layer in the embodiments of this application does not contain Li4Ti5O. 12 These include unstable materials with low melting points, such as titanium-based materials and Li-In, which can react with binder precursors.

[0091] In some embodiments, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector includes one or more of metal foil and composite current collector. For example, one or more of copper foil, stainless steel foil, nickel foil, and titanium foil can be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (copper, copper alloy, stainless steel, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate [such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.].

[0092] Under the condition that the solid-state battery cell meets the following condition 1), the negative electrode sheet of the present application embodiment can be prepared by the following method:

[0093] A negative electrode active layer comprising a negative electrode active material and a first binder precursor is prepared on at least one side of the negative electrode current collector. The first binder precursor includes the structural unit shown in Formula II.

[0094] This causes the first adhesive precursor to undergo a cross-linking reaction;

[0095]

[0096] Formula II, n = 10000 ~ 100000.

[0097] A schematic diagram of the negative electrode preparation can be found here. Figure 1If the first adhesive precursor includes the structural unit shown in Formula II, then the crosslinking reaction of the first adhesive precursor includes intermolecular crosslinking of the first adhesive precursor and intramolecular cyclization (therefore, causing the first adhesive precursor to undergo a crosslinking reaction can also be described as causing the first adhesive precursor to undergo a cyclization reaction), generating a first adhesive containing the structural unit shown in Formula I or its tautomer.

[0098] The preparation method of this application embodiment can form a first binder containing the structural unit shown in Formula I or its tautomer in the negative electrode active layer. The conjugated structure in the structural unit shown in Formula I or its tautomer can provide a fast ion / electron transport channel between the negative electrode active material particles, so that the negative electrode sheet exhibits low resistance and high ion / electron transport capability, thereby improving the cycle performance of solid-state batteries at high rates.

[0099] In some embodiments, the mass content of the first binder precursor in the negative electrode active layer is 3% to 10%, optionally 4% to 6%, for example, any one of 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range between any two. The mass content of the first binder precursor in the negative electrode active layer can be calculated based on the amount of raw materials used; or the mass content of the first binder precursor in the negative electrode active layer can be determined by thermogravimetric analysis based on different pyrolysis temperatures. At this content, a certain amount of first binder comprising the structural unit shown in Formula I or its tautomers, with high ion / electron transport performance, can be generated using the first binder precursor, giving the negative electrode suitable conductivity, which is beneficial for improving the cycle performance of the solid-state battery at high rates. Furthermore, when the mass content of the first binder precursor in the negative electrode active layer is 4% to 6%, both the first binder precursor and the generated first binder have good uniformity in the negative electrode active layer, which can enable the solid-state battery to exhibit better performance.

[0100] Understandably, because the first binder precursor may undergo a cracking reaction during the crosslinking reaction, generating small molecule gases or causing some structures to detach from the molecular chain, the mass of the resulting first binder is usually lower than the mass of the first binder precursor added during the preparation process. Typically, when the mass content of the first binder precursor in the negative electrode active layer is 3% to 10%, the mass content of the resulting first binder in the negative electrode active layer is estimated to be 2% to 9%; when the mass content of the first binder precursor in the negative electrode active layer is 4% to 6%, the mass content of the resulting first binder in the negative electrode active layer is estimated to be 3% to 5%.

[0101] In some embodiments, the first binder precursor includes a PAN-based polymer. A PAN-based polymer is a polymer containing a PAN structure, which can be PAN itself or PAN with added substituents or other molecular segments, containing the structural unit shown in Formula II. In the cyclization reaction, the PAN-based polymer can generate a cyclized PAN-based polymer. Cyclic PAN-based polymers possess high ion / electron transport capabilities, which is beneficial for improving the ion / electron transport performance of the negative electrode. Furthermore, cyclized PAN-based polymers have high viscosity, which can improve the cohesion of the negative electrode sheet. The combined effect can effectively improve the cycle performance of solid-state batteries at high rates.

[0102] In some embodiments, the weight-average molecular weight of the first binder precursor is 100,000 to 500,000, optionally 200,000 to 400,000, for example, any one of 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, or 500,000, or a range between any two. The weight-average molecular weight of the first binder precursor in the raw material can be determined using methods such as light scattering or gel permeation chromatography. The first binder precursor at this molecular weight can undergo a cross-linking reaction at a relatively fast reaction rate, generating a stable, highly viscous first binder.

[0103] In some embodiments, the method for causing the first binder precursor to undergo a crosslinking reaction includes heat treatment under a protective atmosphere. The heat treatment temperature is 200°C to 350°C, optionally 280°C to 320°C, for example, any one of 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 340°C, 350°C, or a range between both. The heat treatment time is 4 hours to 9 hours, optionally 4 hours to 6 hours, for example, any one of 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or a range between both. The protective atmosphere includes one or more of nitrogen, helium, argon, and vacuum atmospheres.

[0104] Understandably, the heat treatment time can be adaptively adjusted according to the temperature. Generally, a higher heat treatment temperature allows for a shorter time, while a lower temperature allows for a longer time. Heat treatment under a protective atmosphere enables the first binder precursor, including the structural unit shown in Formula II, to undergo intermolecular and intramolecular crosslinking, generating a first binder including the structural unit shown in Formula I or its tautomers. The conjugated structure in the structural unit shown in Formula I or its tautomers can provide rapid ion / electron transport channels between the negative electrode active material particles, which is beneficial for improving the cycle performance of solid-state batteries at high rates. Furthermore, by controlling the temperature and time of the heat treatment, the generated first binder can have a suitable degree of cyclization, which can both improve the cohesion of the negative electrode sheet and give the negative electrode sheet suitable conductivity. When applied to solid-state batteries, the negative electrode sheet can have good compatibility with most solid electrolyte membranes in solid-state batteries, mitigating the phenomenon of solid electrolyte membrane decomposition caused by excessive conductivity.

[0105] In some embodiments, the Dv50 of the negative electrode active material is 10 nm to 20 μm, optionally 1 μm to 20 μm, for example, any point value or range between any two of 10 nm, 50 nm, 100 nm, 200 nm, 400 nm, 600 nm, 800 nm, 1 μm, 2 μm, 4 μm, 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, and 20 μm. The particle size distribution of the material is usually expressed as the percentage of particles within different particle size ranges. There are various benchmarks for determining particle size distribution, such as number distribution, length distribution, area distribution, volume distribution, and weight distribution. Dv50 is a specific particle size distribution based on volume distribution, also known as the median particle size, which refers to the particle size at which the cumulative volume distribution is 50%, indicating that 50% of the particles have a diameter exceeding this value and 50% of the particles have a diameter below this value. The Dv50 of the particles can be obtained by referring to GB / T 19077-2016 / ISO 13320:2009 "Particle size distribution - Laser diffraction method". The embodiments of this application can use negative electrode active materials of various particle sizes as raw materials to prepare negative electrode sheets, and the method has good universality.

[0106] In some embodiments, the negative electrode active layer in the above preparation method typically does not contain conductive agents, such as vapor-grown carbon fiber (VGCF), carbon dots, carbon nanotubes, graphene, carbon nanofibers, etc. These conductive agents would confine the cross-linking reaction of the structural unit shown in Formula II and affect the cohesion of the negative electrode sheet.

[0107] Understandably, if a solid-state battery cell does not meet condition 1) [in which case the solid-state battery cell needs to meet condition 2)], the negative electrode active layer may contain negative electrode active material, solid electrolyte, conductive agent, binder, and may also contain other additives that can improve the performance of the negative electrode sheet.

[0108] The conductive agent may include one or more of the following: vapor-grown carbon fiber (VGCF), superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The mass content of the conductive agent in the negative electrode active layer may be 1% to 5%, for example, it may be any one of 1%, 2%, 3%, 4%, and 5%, or any range between two values.

[0109] The binder may include one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene-butadiene rubber (SBR). The mass content of the binder in the negative electrode active layer may be 0.5% to 5%, for example, any one of 0.5%, 1%, 2%, 3%, 4%, and 5%, or a range between any two.

[0110] Solid electrolytes include one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer solid electrolytes, and optionally include sulfide solid electrolytes. Sulfide solid electrolytes include one or more of Li6PS5Cl, Li2S-GeS2, Li2S-P2S5, Li2S-SiS2, and Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.). Halide solid electrolytes include one or more of Li3YCl6, Li3InCl6, Li3ErCl6, Li3ScCl6, Li3HoCl6, Li2MnCl4, Li2MnCl5, and Li6FeCl8. Oxide solid electrolytes include lithium oxide garnet (Li7La3Zr2O). 12 The solid electrolyte comprises one or more of the following: LLZO, tin oxide (SnO2), and bismuth oxide (Bi2O3). Polymer solid electrolytes include one or more of polyethylene oxide electrolytes, polycarbonate electrolytes, and polysiloxane electrolytes. The mass content of the solid electrolyte in the negative electrode active layer can include 20% to 30%, optionally 25% to 27%, for example, any one of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%, or a range between any two.

[0111] In this case, the negative electrode sheet can be prepared by the following method:

[0112] The components used to prepare the negative electrode sheet, such as negative electrode active material, solid electrolyte, conductive agent, binder and any other components, are mixed to form a negative electrode slurry. The negative electrode slurry is coated on the negative electrode current collector and then dried and cold-pressed to obtain the negative electrode sheet.

[0113] [Positive electrode plate]

[0114] Similar to the case where a solid-state battery cell satisfies condition 1), when a solid-state battery cell satisfies condition 2), i.e., when the second binder includes the structural unit shown in Formula I or its tautomer, some characteristics of the positive electrode sheet are as follows.

[0115] In some embodiments, the mass content of the second binder in the positive electrode active layer is 2% to 9%, optionally 3% to 5%, for example, any one of 2%, 3%, 4%, 5%, 6%, 7%, 8%, or 9%, or a range between any two. Since the thermal decomposition temperature of the second binder differs from that of the positive electrode active material and other substances in the positive electrode active layer, the mass content of the second binder in the positive electrode active layer can be determined using thermogravimetric analysis. At this second binder content, the ion / electron transport performance of the positive electrode sheet can be effectively improved, enhancing the cycle performance of the solid-state battery at high rates. Furthermore, when the mass content of the second binder in the positive electrode active layer is 3% to 5%, the second binder exhibits good uniformity in the positive electrode active layer, resulting in a flat positive electrode sheet and better performance of the solid-state battery. Additionally, at this mass content, the second binder does not excessively occupy the proportion of the positive electrode active material used to provide capacity, which is beneficial for improving the energy density of the positive electrode sheet.

[0116] In some embodiments, the second binder comprises a cyclized PAN polymer.

[0117] Cyclic PAN polymers have high ion / electron transport capabilities, which are beneficial to improving the ion / electron transport performance of the cathode. In addition, cyclic PAN polymers have high viscosity, which can improve the cohesion of the cathode sheet. Under the combined effect, they can effectively improve the cycle performance of solid-state batteries at high rates.

[0118] In some embodiments, the thickness of the positive electrode active layer is 10 μm to 30 μm, for example, any one of 10 μm, 15 μm, 20 μm, 25 μm, 30 μm or a range between any two.

[0119] The thickness of the positive electrode active layer in this application embodiment can be designed as needed and is not limited to the thickness range listed above. For positive electrode active layers of different thicknesses, the solutions adopted in this application embodiment can improve the cycle performance of solid-state batteries at high rates.

[0120] In some embodiments, the positive electrode active material includes one or more of lithium phosphates having an olivine structure and their modified compounds, lithium transition metal oxides and their modified compounds. Examples of lithium phosphates having an olivine structure include lithium iron phosphate (such as LiFePO4, i.e., LFP), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxides may include lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides [such as LiNi]. 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 O2), lithium niobium oxides (such as lithium niobate), lithium titanium oxides (such as Li4Ti5O) 12 One or more of these positive electrode active materials and their modified compounds. These positive electrode active materials can be used alone or in combination of two or more.

[0121] Understandably, this application is not limited to these materials, and other materials that can be used as positive electrode active materials in batteries may also be used. The second binder containing the structural unit shown in Formula I or its tautomer is usually obtained by cyclizing the corresponding second binder precursor at high temperature. Therefore, positive electrode active materials with high stability that do not react with other substances (e.g., the second binder precursor) during the preparation of the positive electrode sheet can usually be selected, thereby reducing the difficulty in forming the positive electrode sheet and successfully obtaining the desired positive electrode sheet.

[0122] In some embodiments, the positive current collector includes two surfaces opposite each other in its own thickness direction, and the positive active layer can be disposed on either or both of the opposite surfaces of the positive current collector. The positive current collector includes one or more of metal foil and composite current collector. For example, aluminum foil can be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate [such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.].

[0123] Under the condition that the solid-state battery cell meets the following condition 2), the positive electrode sheet of the embodiments of this application can be prepared by the following method:

[0124] A positive electrode active layer comprising a positive electrode active material and a second binder precursor is prepared on at least one side of the positive electrode current collector. The second binder precursor includes the structural unit shown in Formula II.

[0125] The second adhesive precursor undergoes a cross-linking reaction;

[0126]

[0127] Formula II, n = 10000 ~ 100000.

[0128] The preparation method of this application embodiment can form a second binder containing the structural unit shown in Formula I or its tautomer in the positive electrode active layer. The conjugated structure in the structural unit shown in Formula I or its tautomer can provide a fast ion / electron transport channel between the positive electrode active material particles, so that the positive electrode sheet exhibits low resistance and high ion / electron transport capability, thereby improving the cycle performance of solid-state batteries at high rates.

[0129] In some embodiments, the mass content of the second binder precursor in the positive electrode active layer is 3% to 10%, optionally 4% to 6%, for example, any one of 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, or a range between any two. At this content, a certain amount of a second binder comprising the structural unit shown in Formula I or its tautomers, with high ion / electron transport performance, can be generated using the second binder precursor, giving the positive electrode suitable conductivity and improving the cycle performance of the solid-state battery at high rates. Furthermore, when the mass content of the second binder precursor in the positive electrode active layer is 4% to 6%, both the second binder precursor and the generated second binder have good uniformity in the positive electrode active layer, which can enable the solid-state battery to exhibit better performance.

[0130] Understandably, since the second binder precursor may undergo a cracking reaction during the crosslinking reaction, generating some small molecule gases, or some structures may fall off from the molecular chain, the quality of the resulting second binder is usually lower than the quality of the second binder precursor added during the preparation process. The amount of reduction can be referenced to the difference between the first binder precursor and the first binder in the negative electrode sheet.

[0131] In some embodiments, the second binder precursor includes a PAN-based polymer. The PAN-based polymer can be converted into a cyclized PAN-based polymer. Cyclic PAN-based polymers have high ion / electron transport capabilities, which is beneficial for improving the ion / electron transport performance of the positive electrode. Furthermore, cyclized PAN-based polymers have high viscosity, which can improve the cohesive force of the positive electrode. The combined effect can effectively improve the cycle performance of solid-state batteries at high rates.

[0132] In some embodiments, the weight-average molecular weight of the second binder precursor is 100,000 to 500,000, optionally 200,000 to 400,000, for example, any one of 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, or 500,000, or a range between any two. The weight-average molecular weight of the second binder precursor in the raw material can be determined using methods such as light scattering or gel permeation chromatography. The second binder precursor at this molecular weight can undergo a cross-linking reaction at a relatively fast reaction rate, generating a stable, highly viscous second binder.

[0133] In some embodiments, the method of causing the second binder precursor to undergo a crosslinking reaction includes heat treatment under a protective atmosphere. The heat treatment temperature is 200°C to 350°C, optionally 280°C to 320°C, for example, any one of 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 340°C, and 350°C, or a range between any two. The heat treatment time is 4 hours to 9 hours, optionally 4 hours to 6 hours, for example, any one of 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, and 9 hours, or a range between any two. The protective atmosphere includes one or more of nitrogen, helium, argon, and vacuum atmospheres.

[0134] Under a protective atmosphere, heat treatment allows the second binder precursor, comprising the structural unit shown in Formula II, to undergo intermolecular and intramolecular crosslinking, generating a first binder comprising the structural unit shown in Formula I or its tautomer. The conjugated structure in the structural unit shown in Formula I or its tautomer can provide rapid ion / electron transport channels between the positive electrode active material particles, which is beneficial for improving the cycle performance of solid-state batteries at high rates. Furthermore, by controlling the temperature and time of the heat treatment, the generated second binder can have a suitable degree of cyclization, which can both improve the cohesion of the positive electrode and give the positive electrode suitable conductivity. When the positive electrode is applied to a solid-state battery, it can have good compatibility with most solid electrolyte membranes in the solid-state battery, mitigating the phenomenon of solid electrolyte membrane decomposition caused by excessive conductivity.

[0135] In the above-mentioned method for preparing the positive electrode sheet, the positive electrode active layer usually does not contain conductive agents, such as vapor-grown carbon fiber (VGCF), carbon dots, carbon nanotubes, graphene, carbon nanofibers, etc. These conductive agents will confine the cross-linking reaction of the structural unit shown in Formula II and affect the cohesion of the positive electrode sheet.

[0136] Understandably, if a solid-state battery cell does not meet condition 2), the positive electrode active layer may contain positive electrode active material, solid electrolyte, conductive agent, binder, and other additives that can improve the performance of the positive electrode sheet.

[0137] The conductive agent may include one or more of the following: vapor-grown carbon fiber (VGCF), superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The mass content of the conductive agent in the positive electrode active layer may be 1% to 5%, for example, it may be any one of 1%, 2%, 3%, 4%, and 5%, or any range between two.

[0138] The binder may include one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene-butadiene rubber (SBR). The mass content of the binder in the positive electrode active layer may be 0.5% to 5%, for example, any one of 0.5%, 1%, 2%, 3%, 4%, and 5%, or any range between two values.

[0139] Solid electrolytes include one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer solid electrolytes, and optionally include sulfide solid electrolytes. Sulfide solid electrolytes include one or more of Li6PS5Cl, Li2S-GeS2, Li2S-P2S5, Li2S-SiS2, and Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.). Halide solid electrolytes include one or more of Li3YCl6, Li3InCl6, Li3ErCl6, Li3ScCl6, Li3HoCl6, Li2MnCl4, Li2MnCl5, and Li6FeCl8. Oxide solid electrolytes include lithium oxide garnet (Li7La3Zr2O). 12 The solid electrolyte comprises one or more of the following: LLZO, tin oxide (SnO2), and bismuth oxide (Bi2O3). Polymer solid electrolytes include one or more of polyethylene oxide electrolytes, polycarbonate electrolytes, and polysiloxane electrolytes. The mass content of the solid electrolyte in the positive electrode active layer can include 20% to 30%, optionally 25% to 27%, for example, any one of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%, or a range between any two.

[0140] In this case, the positive electrode sheet can be prepared by the following method:

[0141] The components used to prepare the positive electrode sheet, such as the positive electrode active material, solid electrolyte, conductive agent, binder, and any other components, are mixed, formed into a film, and pressed to obtain the positive electrode film. The positive electrode film is then combined with a positive electrode current collector to obtain the positive electrode sheet.

[0142] Alternatively, the components used to prepare the positive electrode sheet, such as positive active material, solid electrolyte, conductive agent, binder and any other components, are mixed to form a positive electrode slurry. The positive electrode slurry is coated on the positive current collector and then dried and cold-pressed to obtain the positive electrode sheet.

[0143] [Solid electrolyte membrane]

[0144] The solid-state battery cell in this application includes a solid electrolyte, which is typically used in the form of a membrane, i.e., a solid electrolyte membrane. The solid electrolyte membrane is disposed between the positive and negative electrode plates and is in contact with both plates. During battery charging and discharging, active ions move back and forth between the positive and negative electrode plates, inserting and extracting. The solid electrolyte membrane acts as a conductor of ions between the positive and negative electrode plates.

[0145] The solid electrolyte membrane in this application includes one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer solid electrolytes, and optionally includes sulfide solid electrolytes. Sulfide solid electrolytes include one or more of Li6PS5Cl, Li2S-GeS2, Li2S-P2S5, Li2S-SiS2, and Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.). Halide solid electrolytes include one or more of Li3YCl6, Li3InCl6, Li3ErCl6, Li3ScCl6, Li3HoCl6, Li2MnCl4, Li2MnCl5, and Li6FeCl8. Oxide solid electrolytes include lithium oxide garnet (Li7La3Zr2O). 12 This includes one or more of the following: LLZO, tin oxide (SnO2), and bismuth oxide (Bi2O3). Polymer solid electrolytes include one or more of the following: polyethylene oxide electrolytes, polycarbonate electrolytes, and polysiloxane electrolytes.

[0146] Solid electrolyte membranes can be prepared by the following method:

[0147] A solid electrolyte is mixed with a binder to form a membrane of suitable thickness. In the solid electrolyte membrane, the mass of the binder can be 0.5% to 5%, for example, any one of 0.5%, 1%, 2%, 3%, 4%, or 5%, or a range between any two. The binder in the solid electrolyte membrane includes one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene-butadiene rubber (SBR).

[0148] [Outer Packaging]

[0149] Solid-state battery cells may include an outer packaging that can be used to encapsulate the positive electrode, negative electrode, and solid electrolyte membrane.

[0150] The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell; or it can be a soft package, such as a pouch. The material of the soft package can be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0151] The outer packaging can be cylindrical, square, or any other shape. For example, Figure 2 This is an example of a solid-state battery cell with a square outer packaging structure.

[0152] Reference Figure 3 The outer packaging may include a housing 01 and a cover plate 02. The housing 01 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 01 has an opening communicating with the receiving cavity, and the cover plate 02 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a solid electrolyte membrane can be stacked to form an electrode assembly 03. One or more electrode assemblies 03 are encapsulated within the receiving cavity.

[0153] [Solid-state battery cell]

[0154] In this embodiment, the solid-state battery cell can be a rechargeable battery, which refers to a battery cell that can be recharged after discharge to reactivate its active materials and continue to be used. Optionally, the solid-state battery cell in this embodiment is an all-solid-state lithium-ion battery.

[0155] In the solid-state battery cell of this application embodiment, the binder in the electrode (negative electrode and / or negative electrode) includes the structural unit shown in Formula I or its tautomer. The conjugated structure in the structural unit can provide a fast ion / electron transport channel between the active material particles of the electrode, so that the electrode exhibits low resistance and high ion / electron transport capability, and the solid-state battery exhibits good cycle performance.

[0156] Solid-state battery cells can be assembled as follows: stack the positive electrode, solid electrolyte membrane, and negative electrode in that order, and apply pressure to make the positive electrode and negative electrode in close contact with the solid electrolyte membrane.

[0157] [Battery Device]

[0158] This application provides a battery apparatus including multiple solid-state battery cells. Specifically, the battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A solid-state battery cell assembly may include multiple solid-state battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0159] The solid-state battery cell of this application embodiment has good cycle performance. Therefore, applying the solid-state battery cell to a battery device can help improve the cycle performance of the battery device and extend the service life of the battery device.

[0160] In some implementations, a battery cell assembly is typically formed by arranging multiple solid-state battery cells.

[0161] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple solid-state battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple solid-state battery cells together with cable ties.

[0162] In some implementations, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0163] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0164] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple solid-state battery cells to the housing.

[0165] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0166] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0167] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0168] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use solid-state battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0169] [Energy Storage Device]

[0170] This application provides an energy storage device, including multiple solid-state battery cells or multiple battery devices, wherein the solid-state battery cells or battery devices are used to store or provide electrical energy.

[0171] The aforementioned solid-state battery cells and battery devices with good cycle performance are used to store or provide electrical energy for energy storage devices, which can extend the service life of energy storage devices.

[0172] In some implementations, the energy storage device includes one or more battery clusters to increase the voltage and capacity of the energy storage device. A battery cluster may include multiple battery units connected in series via a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, the battery clusters are connected in parallel to increase the capacity of the energy storage device.

[0173] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, an energy storage device can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours. The energy storage system provided in this application embodiment can be any power system that requires energy storage devices.

[0174] In some implementations, the energy storage device is an energy storage container or an energy storage cabinet.

[0175] In some implementations, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0176] In some implementations, the energy storage device may include modules such as a thermal management module, a main control module, a central control module, a power distribution module, and a fire protection module.

[0177] As an example, the thermal management module may include a liquid cooling unit that supplies coolant to each battery device via piping to regulate the temperature of the individual battery cells.

[0178] As an example, the main control module can serve as the battery management unit for the battery cluster, used to monitor and manage the battery cluster. The main control module can monitor information such as the current, voltage, power, or temperature of the battery cluster. For instance, it can control the charging and discharging current and voltage of the battery cluster. The main control module includes modules such as an auxiliary battery management unit (SBMU) and a fusion switch.

[0179] As an example, the central control module can serve as the battery management unit for an energy storage device, used to monitor and manage the device. The central control module can monitor information such as the energy storage device's current, voltage, power, state of charge, or temperature. For instance, it can control the charging and discharging current and voltage of the energy storage device. As an example, the central control module includes modules such as an Insulation Monitoring Module (IMM), a Master Battery Management Unit (MBMU), an Ethernet (ETH) module, and a fiber optic conversion module.

[0180] As an example, the fire protection module includes a control panel, detectors, alarm devices, etc., used to detect, alarm, or extinguish fires in the energy storage system.

[0181] As an example, a power distribution module can be used to distribute power to modules in an energy storage device that require electricity.

[0182] [Electrical appliances]

[0183] This application provides an electrical device, including the above-mentioned solid-state battery cell or multiple battery devices, wherein the solid-state battery cell or battery devices are used to store or provide electrical energy.

[0184] The aforementioned solid-state battery cells and battery devices with good cycle performance can be used as power sources for electrical devices or as energy storage units for electrical devices, thereby extending the service life of electrical devices.

[0185] Electrical devices may include, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0186] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0187] Example 1

[0188] 1. Negative electrode plate

[0189] Micron-sized silicon material (Dv50 approximately 6 μm) and PAN were mixed at a mass ratio of 95:5 (PAN mass content 5%), and NMP solvent was added. The mixture was stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry was coated onto copper foil, dried, cold-pressed, and then heated in a vacuum tube furnace at 300℃ for 5 hours to allow PAN to spontaneously cyclize and form cyclized PAN, thus obtaining a negative electrode sheet (negative electrode active layer thickness approximately 20 μm).

[0190] 2. Positive electrode plate

[0191] The positive electrode active material NCM811, the sulfide solid electrolyte Li6PS5Cl, and the conductive agent VGCF were uniformly mixed for 10 min at a mass ratio of 70:27:3 to obtain a composite positive electrode powder. PTFE binder, equivalent to 1% of the mass of the first three materials, was added and rolled into a positive electrode film (approximately 20 μm thick).

[0192] 3. Solid electrolyte membrane

[0193] The sulfide solid electrolyte Li6PS5Cl was thoroughly mixed with PTFE binder at 1% of the mass of Li6PS5Cl and rolled into a solid electrolyte membrane.

[0194] 4. Battery assembly

[0195] The negative electrode, solid electrolyte membrane, and positive electrode are stacked in that order from bottom to top. After being subjected to a 600MPa isostatic pressing, the battery cell is obtained, which is then packaged in an aluminum-plastic bag and subjected to battery cell performance testing.

[0196] Example 2

[0197] The difference between this embodiment and Embodiment 1 is that the Dv50 of the micron-sized silicon used in the preparation of the negative electrode sheet is approximately 20 μm.

[0198] Example 3

[0199] The difference between this embodiment and Embodiment 1 is that the Dv50 of the micron-sized silicon used in the preparation of the negative electrode sheet is approximately 0.1 μm.

[0200] Example 4

[0201] The difference between this embodiment and Embodiment 1 is that, in the preparation process of the negative electrode sheet, the mass ratio of micron-sized silicon (Dv50 approximately 6μm) to PAN is 97:3 (PAN mass content is 3%).

[0202] Example 5

[0203] The difference between this embodiment and Embodiment 1 is that, in the preparation process of the negative electrode sheet, the mass ratio of micron-sized silicon (Dv50 approximately 6μm) to PAN is 90:10 (PAN mass content is 10%).

[0204] Comparative Example 1

[0205] The difference between this comparative example and Example 1 is that, in the preparation process of the negative electrode sheet, PAN is replaced with an equal mass of PVDF, and no heating is performed.

[0206] Specifically, the negative electrode sheet of this comparative example was prepared according to the following method:

[0207] Micron-sized silicon material (Dv50 approximately 6μm) and PVDF were mixed at a mass ratio of 95:5, and NMP solvent was added. The mixture was stirred thoroughly to obtain a uniform negative electrode slurry. The negative electrode slurry was coated onto copper foil, dried, and cold-pressed to obtain the negative electrode sheet.

[0208] Performance testing was conducted as follows. During the testing process, the full battery charge / discharge test parameters were as follows: test temperature 25℃~60℃; charge / discharge voltage range: 2.5~4.3V vs. Li+ / Li; positive electrode surface capacity: 3mAh / cm². 2 ~5mAh / cm 2 External pressure applied during testing: 0MPa~5MPa, optionally 0.5MPa~3MPa.

[0209] 1. Negative electrode cohesion

[0210] At 25℃, cut the negative electrode sheet into test specimens of 20mm×100mm size for later use; attach one side of double-sided tape to the surface of the steel plate and the other side to the specimen, and press it with a pressure roller to ensure complete adhesion to the specimen; attach cohesion test tape to the other side of the specimen and press it with a pressure roller; bend one end of the cohesion test tape in the opposite direction at a bending angle of 180°; use a universal tensile testing machine to test, fix one end of the steel plate to the lower clamp of the tensile testing machine, fix the bent end of the current collector of the specimen to the upper clamp, adjust the angle of the current collector to ensure that the upper and lower ends are in a vertical position, and then stretch the specimen at a speed of 50mm / min until the entire negative electrode active layer is peeled off from the surface of the current collector, record the displacement and force during the process, take the force when the force is balanced as the adhesive force of the specimen, and divide this force by the adhesion length of the specimen as the adhesive strength, i.e., the negative electrode cohesion.

[0211] 2. Negative electrode resistor

[0212] At 25℃, the resistance of the negative electrode is measured using a diaphragm resistance meter, i.e., the negative electrode resistance.

[0213] 3. 0.1C discharge capacity, first-efficiency

[0214] At 60℃, charge at a constant current of 0.1C to 4.3V, then switch to constant voltage charging until the current is less than 0.05C. Record the initial charge capacity C1 at 0.1C. Then discharge at 0.1C to 2.5V and record the initial discharge capacity C2 at 0.1C, which is the cell discharge capacity at 0.1C. C2 / C1×100% is the first efficiency.

[0215] 4. 0.33C capacity retention rate of 80% and number of cycles

[0216] At 60℃, charge at a constant current of 0.33C to 4.3V, then switch to constant voltage charging until the current is less than 0.05C, and then discharge at 0.33C to 2.5V. Record the initial discharge capacity C1 at 0.33C. Repeat this cycle X times, and record the discharge capacity C after X cycles. X Until C X / C1≤80%, then X is the number of cycles with a capacity retention of 80% at 0.33C.

[0217] [Table 1]

[0218]

[0219] The batteries corresponding to Examples 1 to 5 exhibit good cycle performance at a relatively high rate of 0.33C, with Example 1 achieving 1500 cycles with 80% capacity retention at 0.33C. This is mainly due to the addition of PAN to the negative electrode slurry and subsequent heat treatment, which generates cyclic PAN with high ion / electron transport performance, effectively improving the ion / electron transport performance of the negative electrode (the negative electrode exhibits low resistance, for example, the negative electrode resistance of Examples 1, 4, and 5 is as low as 0.007Ω to 0.014Ω), thereby significantly improving the battery's cycle performance at high rates. Furthermore, the generated cyclic PAN has high viscosity, which can increase the cohesive force of the negative electrode (for example, the cohesive force of the negative electrode in Example 1 is as high as 128N / m, and the cohesive force of the negative electrode in Example 5 is even as high as 181N / m). This means that the micron-sized silicon particles in the negative electrode have strong bonding forces, which helps maintain the structural stability of the negative electrode during battery cycling and also helps improve the battery's cycle performance at high rates. Meanwhile, the batteries corresponding to Examples 1 to 5 also exhibited high discharge capacity and high initial efficiency at a low rate of 0.1C.

[0220] Comparative Example 1 uses PVDF as a binder, which reduces the battery's discharge capacity at a low rate of 0.1C and its cycle performance at a high rate of 0.33C. This is mainly because PVDF does not have ion / electron transport capabilities, which hinders ion / electron transport. Furthermore, the insufficient viscosity of PVDF reduces the cohesive force of the negative electrode, making it easier for the bonding force between the components in the negative electrode sheet to decrease during cycling, thus affecting the structural stability of the negative electrode sheet.

[0221] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A solid-state battery cell, comprising a negative electrode and a positive electrode; The negative electrode sheet includes a negative current collector and a negative active layer disposed on at least one side of the negative current collector, the negative active layer including a negative active material and a first binder; The positive electrode sheet includes a positive current collector and a positive active layer disposed on at least one side of the positive current collector, the positive active layer including a positive active material and a second binder; Its features are, The solid-state battery cell satisfies one or both of the following conditions 1) and 2): 1) The first adhesive comprises the structural unit shown in Formula I or its tautomer; 2) The second adhesive comprises the structural unit shown in Formula I or its tautomer; Formula I, n=10000~100000.

2. The solid-state battery cell according to claim 1, characterized in that, The first binder has a mass content of 2% to 9% in the negative electrode active layer; and / or, The second binder has a mass content of 2% to 9% in the positive electrode active layer.

3. The solid-state battery cell according to claim 1 or 2, characterized in that, The first binder has a mass content of 3% to 5% in the negative electrode active layer; and / or, The second binder has a mass content of 3% to 5% in the positive electrode active layer.

4. The solid-state battery cell according to any one of claims 1 to 3, characterized in that, The first adhesive comprises a cyclized polyacrylonitrile polymer; and / or, The second adhesive comprises a cyclized polyacrylonitrile polymer.

5. A negative electrode sheet, characterized in that, It includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector, the negative electrode active layer including a negative electrode active material and a first binder; the first binder includes a structural unit of Formula I or a tautomer thereof; Formula I, n=10000~100000.

6. A positive electrode sheet, characterized in that, It includes a positive current collector and a positive active layer disposed on at least one side of the positive current collector, the positive active layer including a positive active material and a second binder; the second binder includes a structural unit of Formula I or a tautomer thereof; Formula I, n=10000~100000.

7. A method for preparing a negative electrode sheet, characterized in that, include: A negative electrode active layer comprising a negative electrode active material and a first binder precursor is prepared on at least one side of the negative electrode current collector. The first binder precursor includes the structural unit shown in Formula II. The first adhesive precursor undergoes a crosslinking reaction; Formula II, n = 10000 ~ 100000.

8. The method for preparing the negative electrode sheet according to claim 7, characterized in that, The first binder precursor has a mass content of 3% to 10% in the negative electrode active layer.

9. The method for preparing the negative electrode sheet according to claim 7 or 8, characterized in that, The first binder precursor has a mass content of 4% to 6% in the negative electrode active layer.

10. The method for preparing the negative electrode sheet according to any one of claims 7 to 9, characterized in that, The first binder precursor includes a polyacrylonitrile polymer.

11. The method for preparing the negative electrode sheet according to any one of claims 7 to 10, characterized in that, A method for causing the first adhesive precursor to undergo a crosslinking reaction includes: heat treatment under a protective atmosphere.

12. The method for preparing the negative electrode sheet according to claim 11, characterized in that, The heat treatment temperature is 200℃~350℃, and the heat treatment time is 4h~9h.

13. The method for preparing the negative electrode sheet according to claim 11 or 12, characterized in that, The heat treatment temperature is 280℃~320℃, and the heat treatment time is 4h~6h.

14. A method for preparing a positive electrode sheet, characterized in that, include: A positive electrode active layer comprising a positive electrode active material and a second binder precursor is prepared on at least one side of the positive electrode current collector, wherein the second binder precursor comprises the structural unit shown in Formula II. The second adhesive precursor undergoes a crosslinking reaction; Formula II, n = 10000 ~ 100000.

15. A battery device, characterized in that, It includes any one of the solid-state battery cells described in claims 1 to 4.

16. An energy storage device, characterized in that, It includes a solid-state battery cell according to any one of claims 1 to 4 or a battery device according to claims 15, wherein the solid-state battery cell or the battery device is used to store or provide electrical energy.

17. An electrical appliance, characterized in that, It includes a solid-state battery cell according to any one of claims 1 to 4 or a battery device according to claims 15, wherein the solid-state battery cell or the battery device is used to store or provide electrical energy.

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