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 satisfies one or both of conditions 1) and condition 2): 1) the negative electrode sheet comprises a first electrolyte layer, the first electrolyte layer is arranged on the surface of a negative active layer; the negative active layer comprises a negative active material and a first binder; the first electrolyte layer comprises a first solid-state electrolyte and a second binder; at least part of the first binder and part of the second binder are crosslinked with each other; 2) the positive electrode sheet comprises a second electrolyte layer, the second electrolyte layer is arranged on the surface of a positive active layer; the positive active layer comprises a positive active material and a third binder; the second electrolyte layer comprises a second solid-state electrolyte and a fourth binder; and at least part of the third binder and part of the fourth binder are crosslinked with each other. The application can improve the electrode interface contact problem caused by electrode volume expansion during long cycle.

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] All-solid-state batteries, using solid electrolytes instead of liquid electrolytes, offer higher safety compared to liquid batteries. The selection of electrode active materials is crucial for improving the energy density of all-solid-state batteries. While some electrode active materials may have high specific capacity and meet energy density requirements, they can expand in volume during battery cycling, leading to interfacial contact failure between the electrode and the solid electrolyte. 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 contact failure between the electrode and the solid electrolyte during battery cycling.

[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; the negative electrode includes a negative current collector and a negative active layer disposed on at least one side of the negative current collector; the positive electrode includes a positive current collector and a positive active layer disposed on at least one side of the positive current collector;

[0006] Solid-state battery cells must satisfy one or both of the following conditions 1) and 2):

[0007] 1) The negative electrode sheet also includes a first electrolyte layer, which is disposed on the surface of the negative electrode active layer; the negative electrode active layer includes a negative electrode active material and a first binder, and the first electrolyte layer includes a first solid electrolyte and a second binder, wherein at least a portion of the first binder and a portion of the second binder are cross-linked.

[0008] 2) The positive electrode also includes a second electrolyte layer, which is disposed on the surface of the positive active layer; the positive active layer includes a positive active material and a third binder, and the second electrolyte layer includes a second solid electrolyte and a fourth binder, wherein at least a portion of the third binder and a portion of the fourth binder are cross-linked.

[0009] In this embodiment, an electrolyte layer (first and / or second) containing a solid electrolyte is formed on the surface of the active layer of the electrode (negative electrode and / or positive electrode). After the electrode sheets are used to assemble a solid-state battery cell, the electrolyte layer on the electrode sheet is in direct contact with the solid electrolyte membrane of the battery cell. Since their compositions are similar or identical (the main component is solid electrolyte), the electrolyte layer and the solid electrolyte membrane can be in close contact, improving the interfacial contact between the electrode and the solid electrolyte. Simultaneously, the binder between the electrode active layer and the electrolyte layer is cross-linked, forming a cross-linked network structure between them, thereby tightly bonding them together. During the operation of the solid-state battery cell, even if the electrode active material expands in volume, the electrolyte layer and the electrode active layer can maintain close contact due to the cross-linking effect of the binder, thus improving the interfacial contact between them.

[0010] Therefore, by setting an electrolyte layer containing a solid electrolyte on the surface of the electrode active layer, and by cross-linking the binder in the electrode active layer and the electrolyte layer, the interfacial contact related to the electrode (including between the electrode active layer and the electrolyte layer, and between the electrolyte layer and the solid electrolyte membrane) can be effectively improved, thus alleviating the problem of poor contact caused by voids between the electrode and the solid electrolyte membrane and inside the electrode during long-term cycling.

[0011] In some embodiments, the first adhesive and the second adhesive each independently comprise the structural unit shown in Formula I or its tautomer.

[0012]

[0013] Formula I, n=10000~100000.

[0014] In some embodiments, the third and fourth adhesives each independently comprise the structural unit shown in Formula I or its tautomer.

[0015]

[0016] Formula I, n=10000~100000.

[0017] Each binder comprises the structural unit shown in Formula I. This type of binder has high viscosity and can tightly bond the electrode active layer and the electrolyte layer together. During the operation of the solid-state battery cell, even if the electrode active material expands in volume, the electrolyte layer and the electrode active layer can maintain tight interfacial contact under the action of the binder, thereby improving the interfacial contact between the electrode active layer and the electrolyte layer.

[0018] In some embodiments, the first adhesive and the second adhesive each independently comprise cyclized PAN (cyclized polyacrylonitrile) polymers.

[0019] In some embodiments, the third and fourth binders each independently comprise cyclized PAN (cyclized polyacrylonitrile) polymers.

[0020] Cyclic PAN polymers have high viscosity, which can tightly bind the electrode active layer and the electrolyte layer together and improve the interfacial contact between the two; and cyclized PAN polymers have high ion and electron transport capabilities, which is beneficial to improving the ion and electron transport performance of the electrode.

[0021] In some embodiments, the mass content of the first binder in the negative electrode active layer is 3% to 8%, optionally 3% to 5%.

[0022] In some embodiments, the mass content of the third binder in the positive electrode active layer is 3% to 8%, optionally 3% to 5%.

[0023] At this binder content, the adhesion between the electrolyte layer and the electrode active layer can be effectively improved, while the binder will not occupy too much of the proportion of active material used to provide capacity, which is beneficial to improving the energy density of the electrode.

[0024] In some embodiments, the mass content of the second binder in the first electrolyte layer is 0.5% to 4%, optionally 2% to 4%.

[0025] In some embodiments, the mass content of the fourth binder in the second electrolyte layer is 0.5% to 4%, optionally 2% to 4%.

[0026] At this binder content, the adhesion between the electrolyte layer and the electrode active layer can be effectively improved, while not excessively occupying the proportion of the solid electrolyte in the electrolyte layer that mainly provides ion and electron conduction, thus enabling the electrode to exhibit good ion and electron conduction performance.

[0027] A second aspect of this application provides a negative electrode sheet, including a negative current collector and a negative active layer disposed on at least one side of the negative current collector; the negative electrode sheet further includes a first electrolyte layer disposed on the surface of the negative active layer; the negative active layer includes a negative active material and a first binder, the first electrolyte layer includes a first solid electrolyte and a second binder, and at least a portion of the first binder and a portion of the second binder are cross-linked.

[0028] By providing a first electrolyte layer containing a first solid electrolyte on the surface of the negative electrode active layer, and having cross-linking between the binder in the negative electrode active layer and the first electrolyte layer, the interfacial contact related to the negative electrode (including between the negative electrode active layer and the first electrolyte layer, and between the first electrolyte layer and the solid electrolyte membrane) can be effectively improved, thus alleviating the problem of poor contact caused by voids appearing between the negative electrode and the solid electrolyte membrane and inside the negative electrode during long-term cycling.

[0029] 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 electrode sheet further includes a second electrolyte layer disposed on the surface of the positive active layer; the positive active layer includes a positive active material and a third binder, the second electrolyte layer includes a second solid electrolyte and a fourth binder, and at least a portion of the third binder and a portion of the fourth binder are cross-linked.

[0030] By setting a second electrolyte layer containing a second solid electrolyte on the surface of the positive electrode active layer, and the binder in the positive electrode active layer and the second electrolyte layer are cross-linked, the interfacial contact related to the positive electrode (including between the positive electrode active layer and the second electrolyte layer, and between the second electrolyte layer and the solid electrolyte membrane) can be effectively improved, and the problem of poor contact caused by voids appearing between the negative electrode and the solid electrolyte membrane and inside the positive electrode during long-term cycling can be alleviated.

[0031] The fourth aspect of this application provides a method for preparing a negative electrode sheet, comprising:

[0032] 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;

[0033] A first electrolyte layer comprising a first solid electrolyte and a second binder precursor is prepared on the surface of the negative electrode active layer.

[0034] This causes a crosslinking reaction between the first adhesive precursor and the second adhesive precursor.

[0035] In this embodiment, a first electrolyte layer containing a solid electrolyte is provided on the surface of the negative electrode active layer. After the electrode sheet is used to assemble a solid battery cell, the electrolyte layer on the electrode sheet is in direct contact with the solid electrolyte membrane of the battery cell. Since the two have similar or identical components (the main component is solid electrolyte), the electrolyte layer and the solid electrolyte membrane can be in close contact, which improves the interfacial contact between the negative electrode and the solid electrolyte membrane.

[0036] Simultaneously, through the cross-linking reaction between the first binder precursor in the negative electrode active layer and the second binder precursor in the first electrolyte layer, a portion of the generated binder chain segments are located in the negative electrode active layer and a portion of the chain segments are located in the first electrolyte layer. That is, at least a portion of the generated first binder and a portion of the second binder are cross-linked with each other, thereby forming a cross-linked network structure at the interface between the negative electrode active layer and the first electrolyte layer, enhancing the adhesion between the negative electrode active layer and the first electrolyte layer, and improving the contact between the first electrolyte layer and the negative electrode active layer.

[0037] Therefore, through the preparation method of this application embodiment, a first electrolyte layer containing a first solid electrolyte can be formed on the surface of the negative electrode active layer, and the binder in the negative electrode active layer and the first electrolyte layer are cross-linked with each other, which can effectively improve the interface contact related to the negative electrode (including between the negative electrode active layer and the first electrolyte layer, and between the first electrolyte layer and the solid electrolyte membrane), and alleviate the problem of poor contact caused by gaps between the negative electrode and the solid electrolyte membrane and inside the negative electrode during long-term cycling.

[0038] In some embodiments, the first adhesive precursor and the second adhesive precursor each independently include the structural unit shown in Formula II;

[0039]

[0040] Formula II, n = 10000 ~ 100000.

[0041] In this embodiment, a binder precursor comprising the structural unit shown in Formula II is added during the fabrication of both the negative electrode active layer and the first electrolyte layer. After a cyclization reaction, the binder precursor generates a binder comprising the structural unit shown in Formula I. This binder exhibits strong adhesion, enabling it to tightly bond the negative electrode active layer and the first electrolyte layer. During the operation of the solid-state battery cell, even if the negative electrode active material undergoes volume expansion, the first electrolyte layer and the negative electrode active layer can maintain close contact thanks to the binder comprising the structural unit shown in Formula I.

[0042] In some embodiments, the first binder precursor and the second binder precursor each independently comprise a PAN-based polymer.

[0043] PAN-based polymers can be cyclized to form cyclized PAN-based polymers. Cyclated PAN-based polymers have high viscosity, which can tightly bind the negative electrode active layer and the first electrolyte layer, improving the interfacial contact between the two; and cyclized PAN-based polymers have high ion and electron transport capabilities, which is beneficial to improving the ion and electron transport performance of the negative electrode.

[0044] In some embodiments, the method for causing a crosslinking reaction between the first adhesive precursor and the second adhesive precursor includes heat treatment under a protective atmosphere, wherein the heat treatment temperature is 200°C to 350°C, optionally 280°C to 320°C, and the heat treatment time is 4h to 9h, optionally 4h to 6h.

[0045] Heat treatment under a protective atmosphere allows the first binder precursor and the second binder precursor to undergo a cross-linking reaction, forming a cross-linked network structure at the interface between the first electrolyte layer and the negative electrode active layer, thus improving the interfacial contact between the two.

[0046] In some embodiments, the mass content of the first binder precursor in the negative electrode active layer is 4% to 9%, optionally 4% to 6%.

[0047] At this content, the first binder precursor can undergo a cross-linking reaction to form a cross-linked network structure at the interface, improving the contact between the first electrolyte layer and the negative electrode active layer, while not excessively occupying the proportion of negative electrode active material used to provide capacity, thus maintaining a high energy density of the negative electrode sheet.

[0048] In some embodiments, the second binder precursor has a mass content of 2% to 5% in the first electrolyte layer, optionally 2% to 4%.

[0049] At this content, the second binder precursor can undergo a cross-linking reaction to form a cross-linked network structure at the interface, improving the contact between the first electrolyte layer and the negative electrode active layer. At the same time, it will not excessively occupy the proportion of the solid electrolyte in the first electrolyte layer that mainly provides ion and electron conduction, so that the negative electrode sheet exhibits good ion and electron conduction performance.

[0050] The fifth aspect of this application provides a method for preparing a positive electrode sheet, comprising:

[0051] A positive electrode active layer comprising a positive electrode active material and a third binder precursor is prepared on at least one side of the positive electrode current collector;

[0052] A second electrolyte layer comprising a second solid electrolyte and a fourth binder precursor is prepared on the surface of the positive electrode active layer;

[0053] This causes a crosslinking reaction between the third and fourth adhesive precursors.

[0054] The preparation method of this application embodiment can provide a second electrolyte layer containing a solid electrolyte on the surface of the positive electrode active layer, and the binder in the positive electrode active layer and the second electrolyte layer are cross-linked, which can effectively improve the interfacial contact related to the positive electrode (including between the positive electrode active layer and the second electrolyte layer, and between the second electrolyte layer and the solid electrolyte membrane), and alleviate the problem of poor contact caused by voids between the positive electrode and the solid electrolyte membrane and inside the positive electrode during long-term cycling.

[0055] This application also provides some related devices, including battery devices, energy storage devices, and power consumption devices.

[0056] The battery device includes multiple solid-state battery cells.

[0057] The solid-state battery cell of this application embodiment has high capacity and good cycle performance. Therefore, applying the solid-state battery cell to a battery device can help improve the capacity of the battery device, improve the cycle performance of the battery device, and extend the service life of the battery device.

[0058] Energy storage devices include multiple solid-state battery cells or multiple battery devices, which are used to store or provide electrical energy.

[0059] The aforementioned solid-state battery cells and battery devices with high capacity and good cycle performance are used to store or provide electrical energy for energy storage devices, which can increase the capacity of energy storage devices and extend their service life.

[0060] Electrical devices include the aforementioned solid-state battery cells or battery devices, which are used to store or provide electrical energy.

[0061] The aforementioned solid-state battery cells and battery devices with high capacity and good cycle performance can be used as power sources for electrical devices or as energy storage units for electrical devices, thereby increasing the capacity of electrical devices and extending their service life. Attached Figure Description

[0062] 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.

[0063] Figure 1 This is a schematic diagram illustrating the cyclization reaction process of PAN according to an embodiment of this application;

[0064] Figure 2 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0065] Figure 3 for Figure 2 An exploded view of a battery cell according to one embodiment of this application is shown. Detailed Implementation

[0066] 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.

[0067] 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.

[0068] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0069] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0070] 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 method may also include step (c), indicating 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.

[0071] 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.

[0072] 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).

[0073] 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, all-solid-state lithium batteries using solid-state electrolytes can effectively solve these safety issues during battery use.

[0074] The selection of electrode active materials is crucial for improving the energy density of all-solid-state batteries. For the anode, silicon-based materials are preferred due to their extremely high theoretical specific capacity (3578 mAh / g, Li). 4.4 Si) has garnered significant attention in the field of all-solid-state batteries. Silicon at 0.4V vs. Li + At its lithiation potential, / Li not only prevents lithium metal plating and lithium dendrite growth, but also exhibits higher energy density than other alloy anodes. Furthermore, silicon's extremely high natural abundance, low cost, and environmental friendliness make it the preferred material for the anode side of all-solid-state batteries. However, in silicon-based all-solid-state batteries, the severe volume expansion and contraction of the silicon-based anode causes not only contact loss within the electrode but also contact failure at the electrode-solid electrolyte interface (the appearance of voids between the electrode and the solid electrolyte). Similarly, other anode or cathode active materials also experience contact failure at the electrode-solid electrolyte interface due to volume expansion during battery cycling.

[0075] To address the interfacial contact failure caused by the volume expansion of electrode active materials, related technologies have modified the electrode active materials to reduce their volume effect. However, this still cannot solve the problem of interfacial contact failure between the electrode and the solid electrolyte during long-term cycling. Alternatively, an interfacial modification layer can be placed between the electrode and the solid electrolyte. Although the contact between the interfaces is good before cycling, the volume expansion of the electrode active material during long-term cycling can also create porosity between the electrode and the interfacial modification layer, leading to interfacial contact failure again.

[0076] Based on this, this application provides a solid-state battery cell. The surface of the electrode active layer of the solid-state battery cell is provided with an electrolyte layer containing a solid electrolyte. The electrolyte layer can make good contact with the solid electrolyte membrane of the battery cell. Both the electrode active layer and the electrolyte layer contain an adhesive. The adhesives on both sides are cross-linked to each other, which can tightly cross-link the electrode active layer and the electrolyte layer together. This is beneficial to improving the electrode interface contact problem caused by electrode volume expansion during long-cycle operation.

[0077] Specifically, the solid-state battery cell of this application embodiment includes a negative electrode sheet and a positive electrode sheet; 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 positive electrode sheet includes a positive current collector and a positive active layer disposed on at least one side of the positive current collector;

[0078] Solid-state battery cells must satisfy one or both of the following conditions 1) and 2):

[0079] 1) The negative electrode sheet also includes a first electrolyte layer, which is disposed on the surface of the negative electrode active layer; the negative electrode active layer includes a negative electrode active material and a first binder, and the first electrolyte layer includes a first solid electrolyte and a second binder, wherein at least a portion of the first binder and a portion of the second binder are cross-linked.

[0080] 2) The positive electrode also includes a second electrolyte layer, which is disposed on the surface of the positive active layer; the positive active layer includes a positive active material and a third binder, and the second electrolyte layer includes a second solid electrolyte and a fourth binder, wherein at least a portion of the third binder and a portion of the fourth binder are cross-linked.

[0081] The cross-linking of at least a portion of the first binder and a portion of the second binder refers to the existence of molecular bonds between a portion of the first binder and a portion of the second binder, forming a cross-linked network structure. Since the first binder is distributed in the negative electrode active layer and the second binder is distributed in the first electrolyte layer, the cross-linking of the first binder and the second binder typically occurs at the interface between the negative electrode active layer and the first electrolyte layer. Similarly, the cross-linking of at least a portion of the third binder and a portion of the fourth binder also refers to the existence of molecular bonds between a portion of the third binder and a portion of the fourth binder, forming a cross-linked network structure; this cross-linking occurs at the interface between the positive electrode active layer and the second electrolyte.

[0082] Taking the negative electrode as an example, the presence of crosslinking between the first binder and the second binder can be analyzed using the following method. Specifically, infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) are used to test the negative electrode active layer and the first electrolyte layer to determine their components, and thermogravimetric analysis can be used to test the mass content of each component. A control group is prepared based on the component composition obtained from the test: a negative electrode active layer containing the negative electrode active layer and the first binder is coated on at least one side of the negative electrode current collector, and a first electrolyte layer containing the first electrolyte and the second binder is coated on the surface of the negative electrode active layer. It is generally believed that in the control group prepared in this way, the first binder in the negative electrode active layer and the second binder in the first electrolyte do not have chemical crosslinking. If a test group has the negative electrode structure of this application, since there is cross-linking between the first binder in the negative electrode active layer and the second binder in the first electrolyte, the test group has a stronger bonding force between the negative electrode active layer and the first electrolyte layer compared to the control group where there is no cross-linking. Therefore, atomic force microscopy (AFM) can be used to test the bonding force F1 between the negative electrode active layer and the first electrolyte layer of the test group, and the corresponding bonding force F2 in the control group. If F1 is greater than F2, it can be considered that there is mutual cross-linking between the first binder in the negative electrode active layer and the second binder in the first electrolyte in the test group.

[0083] The same method can be used to analyze the positive electrode.

[0084] In this embodiment, an electrolyte layer (first and / or second) containing a solid electrolyte is formed on the surface of the active layer of the electrode (negative electrode and / or positive electrode). After the electrode sheets are used to assemble a solid-state battery cell, the electrolyte layer on the electrode sheet is in direct contact with the solid electrolyte membrane of the battery cell. Since their compositions are similar or identical (the main component is solid electrolyte), the electrolyte layer and the solid electrolyte membrane can be in close contact, improving the interfacial contact between the electrode and the solid electrolyte. Simultaneously, the binder between the electrode active layer and the electrolyte layer is cross-linked, forming a cross-linked network structure between them, thereby tightly bonding them together. During the operation of the solid-state battery cell, even if the electrode active material expands in volume, the electrolyte layer and the electrode active layer can maintain close contact due to the cross-linking effect of the binder, thus improving the interfacial contact between them.

[0085] Therefore, by setting an electrolyte layer containing a solid electrolyte on the surface of the electrode active layer, and by cross-linking the binder in the electrode active layer and the electrolyte layer, the interfacial contact related to the electrode (including between the electrode active layer and the electrolyte layer, and between the electrolyte layer and the solid electrolyte membrane) can be effectively improved, thus alleviating the problem of poor contact caused by voids between the electrode and the solid electrolyte membrane and inside the electrode during long-term cycling.

[0086] For further information on the characteristics of the negative electrode, positive electrode, and other components in a solid-state battery cell, please refer to the following text.

[0087] [Negative electrode plate]

[0088] When a solid-state battery cell satisfies condition 1), the negative electrode sheet of this application embodiment has the following characteristics.

[0089] In some embodiments, the first adhesive and the second adhesive each independently comprise the structural unit shown in Formula I or its tautomer.

[0090]

[0091] Formula I, n=10000~100000.

[0092] For example, n can be any point value from 10000, 20000, 40000, 60000, 80000, 100000, or a range between any two.

[0093] 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 electrode active layer and electrolyte layer to determine their composition and whether they contain the structural unit shown in Formula I. 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.

[0094]

[0095] Both the first and second binders contain the structural unit shown in Formula I. These binders exhibit high viscosity, enabling them to tightly bond the negative electrode active layer to the first electrolyte layer. During the operation of the solid-state battery cell, even if the negative electrode active material undergoes volume expansion, the first electrolyte layer and the negative electrode active layer can maintain tight interfacial contact under the action of the first and second binders, thereby improving the interfacial contact between the negative electrode active layer and the first electrolyte layer.

[0096] In some embodiments, the first adhesive and the second adhesive each independently comprise cyclized PAN (cyclized polyacrylonitrile) polymers.

[0097] 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 III. Cyclic PAN polymers can be cyclized PAN, or they can be cyclized PAN with added substituents or other molecular segments.

[0098]

[0099] Infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) techniques can be used to test the electrode active layer and electrolyte layer to determine their composition and whether they contain 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.

[0100] Cyclic PAN polymers have high viscosity, which can tightly bind the negative electrode active layer and the first electrolyte layer together, improving the interfacial contact between the two; and cyclized PAN polymers have high ion and electron transport capabilities, which is beneficial to improving the ion and electron transport performance of the negative electrode.

[0101] In some embodiments, the mass content of the first binder in the negative electrode active layer is 3% to 8%, optionally 3% to 5%, for example, any value or range between 3%, 4%, 5%, 6%, 7%, and 8%. Due to the different thermal decomposition temperatures, the mass content of the first binder in the negative electrode active layer can be determined by thermogravimetric analysis after peeling the negative electrode active layer from the first electrolyte layer. At this first binder content, the adhesion between the first electrolyte layer and the negative electrode active layer can be effectively improved, while 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.

[0102] In some embodiments, the mass content of the second binder in the first electrolyte layer is 0.5% to 4%, optionally 2% to 4%, for example, any one of 0.5%, 1%, 2%, 3%, and 4%, or a range between any two. Similarly, the first electrolyte layer can be peeled off from the negative electrode active layer, and then the mass content of the second binder in the first electrolyte layer can be determined by thermogravimetric analysis. At this second binder content, the adhesion between the second electrolyte layer and the negative electrode active layer can be effectively improved, while not excessively occupying the proportion of the first solid electrolyte in the first electrolyte layer that mainly provides ion and electron conduction, thus enabling the negative electrode to exhibit good ion and electron conduction performance.

[0103] 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.

[0104] In some embodiments, the thickness of the first electrolyte layer is 5 μm to 20 μm, for example, any one of 5 μm, 10 μm, 15 μm, 20 μm or a range between any two.

[0105] The thickness of the negative electrode active layer and the thickness of the first electrolyte layer in the embodiments of this application can be designed as needed and are not limited to the thickness ranges listed above. For negative electrode active layers and first electrolyte layers of different thicknesses, the schemes of the embodiments of this application can improve the interfacial contact between the two after long-term cycling.

[0106] In some embodiments, the negative electrode active material includes one or more of silicon-based materials, graphite (artificial graphite, natural graphite), 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.

[0107] Understandably, this application is not limited to these materials, and other materials that can be used as negative electrode active materials in batteries can also be used. The first binder containing the structural unit shown in Formula I is usually obtained by cyclizing the corresponding polymer precursor at high temperature, so a negative electrode active material that can remain stable at the corresponding cyclization temperature can be selected. These negative electrode active materials can be used alone or in combination of two or more. The negative electrode active layer of this application can use various negative electrode active materials, including silicon-based materials and other negative electrode active materials that are prone to volume expansion. Even when the negative electrode active material expands in volume during battery cycling, the negative electrode active layer and the first electrolyte layer can still maintain a tight bond.

[0108] In some embodiments, the first solid electrolyte includes one or more of sulfide solid electrolytes, halide solid electrolytes, and oxide solid electrolytes, optionally including 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 That is, one or more of LLZO, tin oxide (SnO2), and bismuth oxide (Bi2O3).

[0109] Understandably, this application is not limited to these materials, and other materials that can be used as solid electrolytes may also be used. The first binder containing the structural unit shown in Formula I is typically obtained by cyclizing the corresponding polymer precursor at high temperature, thus allowing the selection of a solid electrolyte that can remain stable at the corresponding cyclization temperature. These solid electrolytes may be used alone or in combination of two or more. Sulfide solid electrolytes, halide solid electrolytes, and oxide solid electrolytes possess high ionic conductivity, good mechanical properties, and stability, which are beneficial for improving the cycle performance of solid-state battery cells.

[0110] 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.].

[0111] 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:

[0112] 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;

[0113] A first electrolyte layer comprising a first solid electrolyte and a second binder precursor is prepared on the surface of the negative electrode active layer.

[0114] This causes a crosslinking reaction between the first adhesive precursor and the second adhesive precursor.

[0115] This process involves a crosslinking reaction between the first and second binder precursors, including a partial (or all) crosslinking reaction between the first and second binder precursors. Typically, the first and second binder precursors have a large contact area at the interface between the negative electrode active layer and the first electrolyte layer, thus the probability of a crosslinking reaction is higher at this location. However, due to molecular diffusion, crosslinking can also occur between the first and second binder precursors outside the contact interface. Simultaneously, intermolecular crosslinking can also occur between the first and second binder precursors, and between the second and third binder precursors, both during the crosslinking reaction.

[0116] In this embodiment, a first electrolyte layer containing a solid electrolyte is provided on the surface of the negative electrode active layer. After the electrode sheet is used to assemble a solid battery cell, the electrolyte layer on the electrode sheet is in direct contact with the solid electrolyte membrane of the battery cell. Since the two have similar or identical components (the main component is solid electrolyte), the electrolyte layer and the solid electrolyte membrane can be in close contact, which improves the interfacial contact between the negative electrode and the solid electrolyte membrane.

[0117] Simultaneously, through the cross-linking reaction between the first binder precursor in the negative electrode active layer and the second binder precursor in the first electrolyte layer, a portion of the generated binder chain segments are located in the negative electrode active layer and a portion of the chain segments are located in the first electrolyte layer. That is, at least a portion of the generated first binder and a portion of the second binder are cross-linked with each other, thereby forming a cross-linked network structure at the interface between the negative electrode active layer and the first electrolyte layer, enhancing the adhesion between the negative electrode active layer and the first electrolyte layer, and improving the contact between the first electrolyte layer and the negative electrode active layer.

[0118] Therefore, through the preparation method of this application embodiment, a first electrolyte layer containing a first solid electrolyte can be formed on the surface of the negative electrode active layer, and the binder in the negative electrode active layer and the first electrolyte layer are cross-linked with each other, which can effectively improve the interface contact related to the negative electrode (including between the negative electrode active layer and the first electrolyte layer, and between the first electrolyte layer and the solid electrolyte membrane), and alleviate the problem of poor contact caused by gaps between the negative electrode and the solid electrolyte membrane and inside the negative electrode during long-term cycling.

[0119] In some embodiments, the first adhesive precursor and the second adhesive precursor each independently include the structural unit shown in Formula II;

[0120]

[0121] Formula II, n = 10000 ~ 100000.

[0122] In the case of the structural unit shown in Formula II, the first and second adhesive precursors undergo crosslinking and cyclization reactions simultaneously to generate an adhesive containing the structural unit shown in Formula I. The cyclization reactions in this process include intramolecular cyclization of the first adhesive precursor itself, intramolecular cyclization of the second adhesive precursor itself, cyclization between the first and second adhesive precursor molecules simultaneously during crosslinking, cyclization between the second and third adhesive precursor molecules simultaneously during crosslinking, and cyclization between the first and second adhesive precursor molecules simultaneously during crosslinking.

[0123] In this embodiment, a binder precursor comprising the structural unit shown in Formula II is added during the fabrication of both the negative electrode active layer and the first electrolyte layer. After a cyclization reaction, the binder precursor generates a binder comprising the structural unit shown in Formula I. This binder exhibits strong adhesion, enabling it to tightly bond the negative electrode active layer and the first electrolyte layer. During the operation of the solid-state battery cell, even if the negative electrode active material undergoes volume expansion, the first electrolyte layer and the negative electrode active layer can maintain close contact thanks to the binder comprising the structural unit shown in Formula I.

[0124] In some embodiments, the first and second binder precursors each independently comprise a PAN-based polymer. PAN-based polymers are polymers containing a PAN structure, and can be PAN (see schematic diagram of the cyclization reaction process of PAN). Figure 1 (As shown in Figure II), it can also be achieved by adding substituents or other molecular chain segments to the PAN structure, containing the structural unit shown in Formula II. PAN polymers can be cyclized to form cyclized PAN polymers through cyclization reactions. Cyclated PAN polymers have high viscosity, which can tightly bind the negative electrode active layer and the first electrolyte layer, improving their interfacial contact; and cyclized PAN polymers have high ion and electron transport capabilities, which is beneficial for improving the ion and electron transport performance of the negative electrode.

[0125] In some embodiments, the method for causing a crosslinking reaction between the first binder precursor and the second binder precursor 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. During heat treatment under a protective atmosphere, the first binder precursor and the second binder precursor can undergo a crosslinking reaction, forming a crosslinked network structure at the interface between the first electrolyte layer and the negative electrode active layer, thereby improving the interfacial contact between the two.

[0126] In some embodiments, the weight-average molecular weights of the first and second binder precursors are independently between 100,000 and 500,000, optionally between 200,000 and 400,000, for example, any one of 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, and 500,000, or any range between the two. The weight-average molecular weights of the first and second binder precursors in the raw material can be determined using methods such as light scattering and gel permeation chromatography. The weight-average molecular weight affects the reactivity of the polymer. Binder precursors at this molecular weight can undergo crosslinking reactions at a faster reaction rate.

[0127] In some embodiments, the mass content of the first binder precursor in the negative electrode active layer is 4% to 9%, optionally 4% to 6%, for example, any one of 4%, 5%, 6%, 7%, 8%, or 9%, or a range between any two. At this content, the first binder precursor can undergo a cross-linking reaction to form a cross-linked network structure at the interface, improving the contact between the first electrolyte layer and the negative electrode active layer, while not excessively occupying the proportion of negative electrode active material used to provide capacity, thus maintaining a high energy density in the negative electrode sheet.

[0128] In some embodiments, the mass content of the second binder precursor in the first electrolyte layer is 2% to 5%, optionally 2% to 4%, for example, any value among 2%, 3%, 4%, and 5%, or any range between two. At this content, the second binder precursor can undergo a cross-linking reaction to form a cross-linked network structure at the interface, improving the contact between the first electrolyte layer and the negative electrode active layer, while not excessively occupying the proportion of the solid electrolyte in the first electrolyte layer that mainly provides ion and electron conduction, thus enabling the negative electrode sheet to exhibit good ion and electron conduction performance.

[0129] Understandably, since the first binder precursor and the second binder precursor may undergo a cracking reaction during heat treatment, generating some small molecule gases, or some structures may fall off from the molecular chain, the quality of the obtained first binder and second binder is usually lower than that of the first binder precursor and the second binder precursor added during the preparation process.

[0130] 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.

[0131] In some embodiments, the negative electrode active layer and the first electrolyte layer in the above preparation method typically do 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 cyclization reaction of the structural unit shown in Formula I, causing a decrease in the adhesion between the negative electrode active layer and the first electrolyte layer.

[0132] Understandably, if a solid-state battery cell does not meet condition 1) [in which case the solid-state battery cell must meet condition 2)], that is, the surface of the negative electrode active layer does not have a first electrolyte layer, and / or the first binder in the negative electrode active layer and the second binder in the first electrolyte layer are not cross-linked, the negative electrode active layer may contain a negative electrode active material, a solid electrolyte, a conductive agent, a binder, and may also contain other additives that can improve the performance of the negative electrode sheet.

[0133] 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.

[0134] 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.

[0135] The type of solid electrolyte can be selected with reference to the first solid electrolyte mentioned above. The mass content of the solid electrolyte in the negative electrode active layer can be 20% to 30%, optionally 25% to 27%, for example, any one of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30% or any range between two.

[0136] The negative electrode sheet for solid-state battery cells that do not meet condition 1) can be prepared by the following method:

[0137] 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 the negative electrode sheet is obtained by drying and cold pressing.

[0138] [Positive electrode plate]

[0139] Similar to the case where a solid-state battery cell satisfies condition 1), when the solid-state battery cell satisfies condition 2), i.e., the positive electrode also includes a second electrolyte layer disposed on the surface of the positive electrode active layer; the positive electrode active layer includes a positive electrode active material and a third binder; the second electrolyte layer includes a second solid electrolyte and a fourth binder; and at least a portion of the third binder and a portion of the fourth binder are cross-linked, some characteristics of the positive electrode are as follows.

[0140] In some embodiments, the third and fourth adhesives each independently comprise the structural unit shown in Formula I or its tautomer.

[0141]

[0142] Formula I, n=10000~100000.

[0143] Both the third and fourth binders contain the structural unit shown in Formula I. These binders have high viscosity and can tightly bond the positive electrode active layer and the second electrolyte layer together. During the operation of the solid-state battery cell, even if the positive electrode active material expands in volume, the positive electrode active layer and the second electrolyte layer can maintain tight interfacial contact under the action of the third and fourth binders, thereby improving the interfacial contact between the positive electrode active layer and the second electrolyte layer.

[0144] In some embodiments, the third and fourth binders each independently comprise cyclized PAN polymers.

[0145] Cyclic PAN polymers have high viscosity, which can tightly bind the negative electrode active layer and the first electrolyte layer together, improving the interfacial contact between the two; and cyclized PAN polymers have high ion and electron transport capabilities, which is beneficial to improving the ion and electron transport performance of the negative electrode.

[0146] In some embodiments, the mass content of the third binder in the positive electrode active layer is 3% to 8%, optionally 3% to 5%, for example, any one of 3%, 4%, 5%, 6%, 7%, and 8%, or a range between any two. At this third binder content, the adhesion between the second electrolyte layer and the positive electrode active layer can be effectively improved, while the third binder does not excessively occupy the proportion of the positive electrode active material used to provide capacity, which is beneficial to improving the energy density of the positive electrode sheet.

[0147] In some embodiments, the mass content of the fourth binder in the second electrolyte layer is 0.5% to 4%, optionally 2% to 4%, for example, any one of 0.5%, 1%, 2%, 3%, and 4%, or a range between any two. At this fourth binder content, the adhesion between the second electrolyte layer and the positive electrode active layer can be effectively improved, while not excessively occupying the proportion of the second solid electrolyte, which mainly provides ion and electron conduction, in the second electrolyte layer, thus enabling the positive electrode to exhibit good ion and electron conduction performance.

[0148] 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.

[0149] In some embodiments, the thickness of the second electrolyte layer is 5 μm to 20 μm, for example, any one of 5 μm, 10 μm, 15 μm, 20 μm or a range between any two.

[0150] The thicknesses of the positive electrode active layer and the second electrolyte layer in the embodiments of this application can be designed as needed and are not limited to the thickness ranges listed above. For positive electrode active layers and second electrolyte layers of different thicknesses, the solutions adopted in the embodiments of this application can improve the interfacial contact between the two after long-term cycling.

[0151] 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 Co0.2 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 the following: positive electrode active materials and their modified compounds. These positive electrode active materials can be used alone or in combination of two or more. The positive electrode active layer of this application can use various positive electrode active materials, and even if the positive electrode active material expands in volume during battery cycling, the positive electrode active layer and the second electrolyte layer can still maintain a tight bond.

[0152] In some embodiments, the second solid electrolyte includes one or more of sulfide solid electrolytes, halide solid electrolytes, and oxide solid electrolytes, optionally including 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 second electrolyte is one or more of the following: LLZO, tin oxide (SnO2), and bismuth oxide (Bi2O3). Understandably, when both conditions 1) and 2) are met in a solid-state battery cell, the second electrolyte can be the same as or different from the first electrolyte. To improve the compatibility between components in a solid-state battery cell, the second electrolyte can be the same as or have similar properties to the first electrolyte.

[0153] 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.].

[0154] 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:

[0155] A positive electrode active layer comprising a positive electrode active material and a third binder precursor is prepared on at least one side of the positive electrode current collector;

[0156] A second electrolyte layer comprising a second solid electrolyte and a fourth binder precursor is prepared on the surface of the positive electrode active layer;

[0157] This causes a crosslinking reaction between the third and fourth adhesive precursors.

[0158] The preparation method of this application embodiment can provide a second electrolyte layer containing a solid electrolyte on the surface of the positive electrode active layer, and the binder in the positive electrode active layer and the second electrolyte layer are cross-linked, which can effectively improve the interfacial contact related to the positive electrode (including between the positive electrode active layer and the second electrolyte layer, and between the second electrolyte layer and the solid electrolyte membrane), and alleviate the problem of poor contact caused by voids between the positive electrode and the solid electrolyte membrane and inside the positive electrode during long-term cycling.

[0159] Similar to the corresponding preparation method of the negative electrode sheet, in some embodiments, the third binder precursor and the fourth binder precursor each independently include the structural unit shown in Formula II;

[0160]

[0161] Formula II, n = 10000 ~ 100000.

[0162] By incorporating a binder precursor containing structural units as shown in Formula II during the fabrication of both the positive electrode active layer and the second electrolyte layer, the binder precursor undergoes a cyclization reaction to generate a binder containing structural units as shown in Formula I. This binder exhibits strong adhesion, enabling it to tightly bond the positive electrode active layer and the second electrolyte layer together. During the operation of the solid-state battery cell, even if the positive electrode active material undergoes volume expansion, the second electrolyte layer and the positive electrode active layer can maintain close contact thanks to the binder containing structural units as shown in Formula I.

[0163] In some embodiments, the third and fourth binder precursors each independently comprise PAN-based polymers.

[0164] In some embodiments, the method for causing a crosslinking reaction between the third and fourth binder precursors 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 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, and 9 hours, or a range between both. The protective atmosphere includes one or more of nitrogen, helium, argon, and vacuum atmospheres.

[0165] In some embodiments, the weight-average molecular weights of the third and fourth binder precursors are independently 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, and 500,000, or any range between the two. The mass content of the third binder precursor in the positive electrode active layer is 5% to 10%, optionally 5% to 8%, for example, any one of 5%, 6%, 7%, 8%, 9%, and 10%, or any range between the two. The mass content of the fourth binder precursor in the second electrolyte layer is 2% to 5%, optionally 2% to 4%, for example, any one of 2%, 3%, 4%, and 5%, or any range between the two.

[0166] In some embodiments, the mass content of the third binder precursor in the positive electrode active layer is 4% to 9%, optionally 4% to 6%, for example, any one of 4%, 5%, 6%, 7%, 8%, 9% or any range between two.

[0167] In some embodiments, the mass content of the fourth binder precursor in the second electrolyte layer is 2% to 5%, optionally 2% to 4%, for example, any one of 2%, 3%, 4%, 5%, or a range between any two.

[0168] In the above-mentioned method for preparing the positive electrode sheet, the positive active layer and the second electrolyte layer usually do not contain conductive agents, such as vapor-grown carbon fiber (VGCF), carbon dots, carbon nanotubes, graphene, carbon nanofibers, etc.

[0169] Understandably, if a solid-state battery cell does not meet condition 2) [in which case the solid-state battery cell must meet condition 1)], that is, if the surface of the positive electrode active layer does not have a second electrolyte layer, and / or the third binder in the positive electrode active layer and the fourth binder in the second electrolyte layer are not cross-linked, the positive electrode active layer may contain positive electrode active material, solid electrolyte, conductive agent, binder, and may also contain other additives that can improve the performance of the positive electrode sheet.

[0170] 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.

[0171] 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.

[0172] The type of solid electrolyte can be selected with reference to the second solid electrolyte mentioned above. The mass content of the solid electrolyte in the positive electrode active layer can be 20% to 30%, optionally 25% to 27%, for example, any one of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or any range between two.

[0173] The positive electrode sheet for solid-state battery cells that do not meet condition 2) can be prepared by the following method:

[0174] 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.

[0175] 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.

[0176] [Solid electrolyte membrane]

[0177] 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.

[0178] The solid electrolyte membrane of the solid-state battery cell in this application embodiment includes one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer solid electrolytes, optionally including 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.

[0179] To improve the compatibility between the solid electrolyte membrane and the electrode, the solid electrolyte membrane can be the same as or have similar properties to the first electrolyte and / or the second electrolyte.

[0180] Solid electrolyte membranes can be prepared by the following method:

[0181] 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).

[0182] [Outer Packaging]

[0183] Solid-state battery cells may include an outer packaging that can be used to encapsulate the positive electrode, negative electrode, and solid electrolyte membrane.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] [Solid-state battery cell]

[0188] 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 the active materials and continue to be used. Optionally, the battery cell in this embodiment is an all-solid-state lithium-ion battery.

[0189] In the solid-state battery cell of this application embodiment, there is good interfacial contact between the electrode and the solid electrolyte membrane, as well as between the active layer of the electrode and the electrolyte layer. Therefore, ions and electrons can be effectively transported between the electrode and the solid electrolyte, resulting in high capacity of the solid-state battery cell. At the same time, these interfaces can still maintain good contact during cycling, resulting in good cycle performance of the solid-state battery cell.

[0190] Solid-state battery cells can be assembled as follows: The positive electrode, solid electrolyte membrane, and negative electrode are stacked in that order, and pressure is applied to ensure close contact between the positive and negative electrodes and the solid electrolyte membrane. During stacking, the first electrolyte layer of the negative electrode is in contact with the solid electrolyte membrane, and / or, the second electrolyte layer of the positive electrode is in contact with the solid electrolyte membrane.

[0191] [Battery Device]

[0192] 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.

[0193] The solid-state battery cell of this application embodiment has high capacity and good cycle performance. Therefore, applying the solid-state battery cell to a battery device can help improve the capacity of the battery device, improve the cycle performance of the battery device, and extend the service life of the battery device.

[0194] In some implementations, a battery cell assembly is typically formed by arranging multiple solid-state battery cells.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple solid-state battery cells to the housing.

[0199] 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.

[0200] 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.

[0201] 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.

[0202] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual 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.

[0203] [Energy Storage Device]

[0204] 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.

[0205] The aforementioned solid-state battery cells and battery devices with high capacity and good cycle performance are used to store or provide electrical energy for energy storage devices, which can increase the capacity of energy storage devices and extend their service life.

[0206] 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.

[0207] 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.

[0208] In some implementations, the energy storage device is an energy storage container or an energy storage cabinet.

[0209] In some implementations, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0210] 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.

[0211] 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.

[0212] 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.

[0213] 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.

[0214] 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.

[0215] As an example, a power distribution module can be used to distribute power to modules in an energy storage device that require electricity.

[0216] [Electrical appliances]

[0217] This application provides an electrical device, including the above-mentioned solid-state battery cell or battery device, wherein the solid-state battery cell or battery device is used to store or provide electrical energy.

[0218] The aforementioned solid-state battery cells and battery devices with high capacity and good cycle performance can be used as power sources for electrical devices or as energy storage units for electrical devices, thereby increasing the capacity of electrical devices and extending their service life.

[0219] 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.

[0220] 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.

[0221] Example 1

[0222] 1. Negative electrode plate

[0223] Micron-sized silicon (DV50 approximately 6 μm) and PAN were mixed at a mass ratio of 95:5 (PAN content in the negative electrode active layer was 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, and cold-pressed to form a negative electrode active layer (approximately 20 μm thick) on the copper foil surface. Subsequently, a sulfide electrolyte (Li6PS5Cl) slurry (xylene solvent) containing 2% wt PAN was uniformly coated onto the surface of the negative electrode active layer. The solvent was removed by vacuum drying, forming an electrolyte layer (approximately 5 μm thick) on the surface of the negative electrode active layer. The mixture was then heated in a vacuum tube furnace at 300 °C for 5 hours to allow PAN to spontaneously cyclize and form cyclized PAN, thus obtaining the negative electrode sheet.

[0224] 2. Positive electrode plate

[0225] 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. A binder PTFE, equivalent to 1% of the mass of the first three materials, was added and rolled into a positive electrode film.

[0226] 3. Solid electrolyte membrane

[0227] 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.

[0228] 4. Battery assembly

[0229] The negative electrode, solid electrolyte membrane, and positive electrode are stacked in a bottom-up order. 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.

[0230] Example 2

[0231] The difference between this embodiment and Embodiment 1 is that micron-sized silicon is replaced with an equal mass of SiO. x Material (DV50 approximately 6 μm). Everything else is the same as in Example 1.

[0232] Example 3

[0233] The difference between this embodiment and Embodiment 1 is that micron-sized silicon is replaced with graphite (DV50 approximately 6μm), and the mass ratio of graphite to PAN in the negative electrode slurry is 97:3. Everything else is the same as in Embodiment 1.

[0234] Example 4

[0235] The difference between this embodiment and Embodiment 1 is that, in the preparation process of the negative electrode sheet, the sulfide solid electrolyte Li6PS5Cl is replaced with an equal mass of Li3InCl6.

[0236] Example 5

[0237] The difference between this embodiment and Embodiment 1 is that in the negative electrode sheet, the mass ratio of micron-sized silicon to PAN is 96:4 (the mass content of PAN in the negative electrode active layer is 4%).

[0238] Example 6

[0239] The difference between this embodiment and Embodiment 1 is that in the negative electrode sheet, the mass ratio of micron-sized silicon to PAN is 91:9 (the mass content of PAN in the negative electrode active layer is 9%).

[0240] Comparative Example 1

[0241] The difference between this comparative example and Example 1 is that the PAN in the negative electrode slurry and the sulfide solid electrolyte slurry is replaced with an equal mass of PVDF, and no heat treatment is performed.

[0242] Specifically, the method for preparing the negative electrode sheet in this comparative example is as follows:

[0243] Micron-sized silicon (DV50 approximately 6 μm) 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 a negative electrode sheet. Subsequently, a sulfide electrolyte (Li6PS5Cl) slurry mixed with 2% wt PVDF (xylene solvent) was uniformly coated onto the surface of the negative electrode sheet, and the solvent was removed by vacuum drying.

[0244] Comparative Example 2

[0245] The difference between this comparative example and Example 1 is that no electrolyte layer is provided in the negative electrode sheet. Specifically, the negative electrode sheet of this comparative example is prepared as follows: micron-sized silicon (DV50 approximately 6 μm) and PAN are mixed at a mass ratio of 95:5, NMP solvent is added, and the mixture is stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry is coated onto copper foil, dried, cold-pressed, and then heated in a vacuum tube furnace at 300°C for 5 hours to allow the PAN to spontaneously cyclize, thus obtaining the negative electrode sheet.

[0246] Perform performance testing using the following methods:

[0247] 1. Adhesion between the electrolyte layer and the negative electrode active layer

[0248] Pressure-sensitive tape is bonded to a stainless steel plate, and then a negative electrode sheet of a certain size is bonded to the pressure-sensitive tape. Next, a layer of green adhesive is bonded to the negative electrode sheet. A tensile testing machine is used to clamp the green adhesive and peel the electrode sheet 180°. The tensile force when the electrolyte layer of the negative electrode sheet begins to peel off from the negative electrode active layer is recorded. This tensile force is usually regarded as the adhesion force between the electrolyte layer and the negative electrode active layer.

[0249] 2. 0.1C discharge capacity

[0250] 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, and then discharge at 0.1C to 2.5V. Record the first discharge capacity C0 at 0.1C, which is the 0.1C discharge capacity.

[0251] 3. 0.33C capacity retention rate of 80% and number of cycles

[0252] 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.

[0253] [Table 1]

[0254]

[0255] Test results show that in the negative electrode sheets of Examples 1 to 4, the electrolyte layer and the negative electrode active layer have a strong adhesion force, reaching 205.3 N / m to 265.6 N / m, which is significantly higher than that of Comparative Example 1, which uses PVDF as a binder (more than 4 times higher). Simultaneously, the discharge capacity of Examples 1 to 4 is higher than that of Comparative Example 1. In particular, the number of cycles at 0.33C to 80% capacity retention for the batteries in Examples 1 to 4 reaches 1980 to 2560 cycles, significantly higher than the 200 cycles in Comparative Example 1. This is mainly due to… If PAN is added to the negative electrode active layer and the electrolyte layer, and then subjected to heat treatment to cause the PAN to undergo a spontaneous cyclization reaction to generate cyclized PAN, cyclized PAN will be generated in situ in the negative electrode active layer and the electrolyte layer. The cyclized PAN in the negative electrode active layer and the cyclized PAN in the electrolyte layer will cross-link at the interface, thereby effectively improving the interfacial contact between the electrolyte layer and the negative electrode active layer and increasing the adhesion between them. Moreover, after long-term cycling, the electrolyte layer and the negative electrode active layer can still maintain good contact, thereby improving the cycle performance of the battery.

[0256] Meanwhile, in Comparative Example 2, no electrolyte layer was provided on the surface of the negative electrode active layer. After the battery was assembled, the negative electrode active layer was in direct contact with the solid electrolyte membrane. As a result, its cycle count was lower than that of Examples 1 to 4. This reflects that the electrolyte layer, as a modification interface between the solid electrolyte membrane and the negative electrode active layer, can improve the interfacial contact between the solid electrolyte membrane and the negative electrode sheet, thereby effectively improving the cycle performance of the battery.

[0257] In addition, Examples 5 and 6 also exhibited performance comparable to that of Example 1.

[0258] 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 comprises a negative current collector and a negative active layer disposed on at least one side of the negative current collector; the positive electrode comprises a positive current collector and a positive active layer disposed on at least one side of the positive current collector; Its features are, The solid-state battery cell satisfies one or both of the following conditions 1) and 2): 1) The negative electrode sheet further includes a first electrolyte layer, which is disposed on the surface of the negative electrode active layer; the negative electrode active layer includes a negative electrode active material and a first binder, and the first electrolyte layer includes a first solid electrolyte and a second binder, wherein at least a portion of the first binder and a portion of the second binder are cross-linked. 2) The positive electrode further includes a second electrolyte layer, which is disposed on the surface of the positive active layer; the positive active layer includes a positive active material and a third binder, and the second electrolyte layer includes a second solid electrolyte and a fourth binder, wherein at least a portion of the third binder and a portion of the fourth binder are cross-linked.

2. The solid-state battery cell according to claim 1, characterized in that, The first adhesive and the second adhesive each independently comprise the structural unit shown in Formula I or its tautomer; and / or, The third adhesive and the fourth adhesive each independently comprise the structural unit shown in Formula I or its tautomer; Formula I, n=10000~100000.

3. The solid-state battery cell according to claim 1 or 2, characterized in that, The first adhesive and the second adhesive each independently comprise a cyclized polyacrylonitrile polymer; and / or, The third and fourth adhesives each independently comprise cyclized polyacrylonitrile polymers.

4. The solid-state battery cell according to any one of claims 1 to 3, characterized in that, In the negative electrode active layer, the mass content of the first binder is 3% to 8%; and / or, In the positive electrode active layer, the mass content of the third binder is 3% to 8%.

5. The solid-state battery cell according to any one of claims 1 to 4, characterized in that, In the negative electrode active layer, the mass content of the first binder is 3% to 5%; and / or, In the positive electrode active layer, the mass content of the third binder is 3% to 5%.

6. The solid-state battery cell according to any one of claims 1 to 5, characterized in that, In the first electrolyte layer, the mass content of the second binder is 0.5% to 4%; and / or, In the second electrolyte layer, the mass content of the fourth binder is 0.5% to 4%.

7. The solid-state battery cell according to any one of claims 1 to 6, characterized in that, In the first electrolyte layer, the mass content of the second binder is 2% to 4%; and / or, In the second electrolyte layer, the mass content of the fourth binder is 2% to 4%.

8. A negative electrode sheet, comprising a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector; Its features are, The negative electrode sheet further includes a first electrolyte layer, which is disposed on the surface of the negative electrode active layer; the negative electrode active layer includes a negative electrode active material and a first binder, and the first electrolyte layer includes a first solid electrolyte and a second binder, wherein at least a portion of the first binder and a portion of the second binder are cross-linked.

9. A positive electrode sheet, comprising a positive current collector and a positive active layer disposed on at least one side of the positive current collector; Its features are, The positive electrode further includes a second electrolyte layer disposed on the surface of the positive active layer; the positive active layer includes a positive active material and a third binder, the second electrolyte layer includes a second solid electrolyte and a fourth binder, and at least a portion of the third binder and a portion of the fourth binder are cross-linked.

10. 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; A first electrolyte layer comprising a first solid electrolyte and a second binder precursor is prepared on the surface of the negative electrode active layer. This causes a crosslinking reaction between the first adhesive precursor and the second adhesive precursor.

11. The method for preparing the negative electrode sheet according to claim 10, characterized in that, The first adhesive precursor and the second adhesive precursor each independently include the structural unit shown in Formula II; Formula II, n = 10000 ~ 100000.

12. The method for preparing the negative electrode sheet according to claim 10 or 11, characterized in that, The first adhesive precursor and the second adhesive precursor each independently comprise a polyacrylonitrile polymer.

13. The method for preparing the negative electrode sheet according to any one of claims 10 to 12, characterized in that, A method for causing a crosslinking reaction between the first adhesive precursor and the second adhesive precursor includes heat treatment under a protective atmosphere.

14. The method for preparing the negative electrode sheet according to claim 13, characterized in that, The heat treatment temperature is 200℃~350℃, and the heat treatment time is 4h~9h.

15. The method for preparing the negative electrode sheet according to claim 13 or 14, characterized in that, The heat treatment temperature is 280℃~320℃, and the heat treatment time is 4h~6h.

16. The method for preparing the negative electrode sheet according to any one of claims 10 to 15, characterized in that, The first binder precursor has a mass content of 4% to 9% in the negative electrode active layer.

17. The method for preparing the negative electrode sheet according to any one of claims 10 to 16, characterized in that, The first binder precursor has a mass content of 4% to 6% in the negative electrode active layer.

18. The method for preparing the negative electrode sheet according to any one of claims 10 to 17, characterized in that, The second binder precursor has a mass content of 2% to 5% in the first electrolyte layer.

19. The method for preparing the negative electrode sheet according to any one of claims 10 to 18, characterized in that, The second binder precursor has a mass content of 2% to 4% in the first electrolyte layer.

20. 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 third binder precursor is prepared on at least one side of the positive electrode current collector; A second electrolyte layer comprising a second solid electrolyte and a fourth binder precursor is prepared on the surface of the positive electrode active layer; A crosslinking reaction occurs between the third adhesive precursor and the fourth adhesive precursor.

21. A battery device, characterized in that, It includes any one of the solid-state battery cells described in claims 1 to 7.

22. An energy storage device, characterized in that, It includes a solid-state battery cell according to any one of claims 1 to 7 or a battery device according to claims 21, wherein the solid-state battery cell or the battery device is used to store or provide electrical energy.

23. An electrical appliance, characterized in that, Includes a solid-state battery cell according to any one of claims 1 to 7 or a battery device according to claim 21, wherein the solid-state battery cell or the battery device is used to store or provide electrical energy.

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