Solid-state battery cell, positive electrode sheet and preparation method therefor, and related apparatus

Abstract

The present application relates to the technical field of batteries, and in particular to a solid-state battery cell, a positive electrode sheet and a preparation method therefor, and a related apparatus. The solid-state battery cell comprises a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode layer arranged on at least one side of the positive electrode current collector; in a direction facing away from the positive electrode current collector, the positive electrode layer comprises a first film layer and a second film layer which are sequentially stacked; the first film layer comprises a positive electrode active material and a first gel electrolyte, and the first gel electrolyte is distributed among the positive electrode active material; and the second film layer comprises a second gel electrolyte. In embodiments of the present application, by distributing the gel electrolyte in both the first film layer and the second film layer of the positive electrode layer, the initial coulombic efficiency and cycle performance of a battery can be improved.

Description

Solid-state battery cells, positive electrode sheets and their preparation methods, and related equipment

[0001] This application claims priority to Chinese Patent Application No. 202411918202.4, filed on December 24, 2024, entitled "Solid-state battery cell, positive electrode sheet and preparation method thereof, and related apparatus", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and in particular to solid-state battery cells, positive electrode sheets and their preparation methods and related apparatus. Background Technology

[0003] Solid-state batteries are a battery technology that uses a solid electrolyte instead of a traditional liquid electrolyte. Compared to traditional liquid batteries, solid-state batteries offer higher safety. However, the battery system still has many problems that urgently need improvement, such as low initial efficiency and insufficient cycle performance. Summary of the Invention

[0004] This application is made in view of the above-mentioned technical problems, and its purpose is to solve the problems of low initial efficiency and insufficient cycle performance of solid-state batteries.

[0005] To achieve the above objectives, this application provides a solid-state battery cell, a positive electrode sheet, a method for preparing the same, and related apparatus.

[0006] The first aspect of this application provides a solid-state battery cell, including a positive electrode sheet, the positive electrode sheet including a positive current collector and a positive electrode layer disposed on at least one side of the positive current collector, the positive electrode layer including a first film layer and a second film layer disposed sequentially in a direction away from the positive current collector; the first film layer including a positive active material and a first gel electrolyte, the first gel electrolyte being distributed between the positive active materials; the second film layer including a second gel electrolyte.

[0007] The embodiments of this application improve the battery's initial efficiency and cycle performance by distributing gel electrolyte in both the first and second films of the positive electrode layer. The mechanism of action is as follows:

[0008] In the first film layer, the first gel electrolyte can fill the voids between the particles of the materials contained in the first film layer (including the positive electrode active material, and optionally also including a conductive agent or other materials), reducing the voids in the positive electrode layer, providing pathways for ion transport between particles, and improving the ion transport performance inside the positive electrode sheet. Simultaneously, the second gel electrolyte in the second film layer can serve as an interface modification layer between the positive electrode sheet and the solid electrolyte membrane of the battery, filling the interface gaps between the positive electrode sheet and the solid electrolyte membrane, compensating for gaps caused by solid-solid contact, effectively improving the solid-solid contact problem that occurs between the positive electrode sheet and the solid electrolyte membrane during charging and discharging, providing pathways for ion transport between the positive electrode sheet and the solid electrolyte membrane, and improving the ion transport performance between the positive electrode sheet and the solid electrolyte membrane. Therefore, by distributing gel electrolytes in both the first and second film layers of the positive electrode layer, ion transport inside the positive electrode sheet and between the positive electrode sheet and the solid electrolyte membrane can be effectively improved simultaneously, thereby benefiting the battery capacity and enabling the battery to have high initial efficiency and good cycle performance.

[0009] In some embodiments, the first gel electrolyte and the second gel electrolyte are in contact at the interface between the first and second membrane layers. That is, the first and second gel electrolytes are continuous without a clear boundary, forming a single integrated structure. This allows for smooth ion transport between the first and second membrane layers and the solid electrolyte membrane, improving the ionic conductivity of the positive electrode, thereby facilitating battery capacity utilization and enhancing initial efficiency and cycle performance.

[0010] In some embodiments, the first gel electrolyte and the second gel electrolyte independently comprise an ionic liquid, a polymer, and inorganic nanoparticles, respectively. Optionally, the first gel electrolyte and the second gel electrolyte have the same composition.

[0011] This type of gel electrolyte is an ionic liquid gel electrolyte with excellent ion transport performance, which is beneficial to improving the ionic conductivity inside and on the surface of the positive electrode, thereby improving the battery's initial efficiency and cycle life.

[0012] In some embodiments, the anion contained in the ionic liquid includes bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI) - ), trifluoromethanesulfonic acid anion (OTf) - One or more of the following.

[0013] The cations contained in ionic liquids include one or more of the following: pyrrolidine cations, imidazole cations, piperidine cations, pyridine cations, and thiophene cations.

[0014] These ionic liquids have excellent stability and ionic conductivity, and do not react with common solid electrolytes, which is beneficial for improving the ion transport performance inside and on the surface of the positive electrode and maintaining the stability of the battery structure.

[0015] In some embodiments, the polymer includes one or more of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), nitrile rubber (NBR), saturated ester polymers, polyacrylonitrile (PAN), polyethylene oxide (PEO), polypropylene oxide (PPO), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and polyvinylidene fluoride (PVDF).

[0016] These polymers utilize their long molecular chain segments to form cross-linked network structures, encapsulating components such as ionic liquids and inorganic nanoparticles to form gels. Furthermore, these polymers exhibit good stability, and the gel electrolyte formed using them as a framework fills the interface gaps between the positive electrode and the solid electrolyte. This protects the positive electrode active material in the positive electrode from direct contact with the solid electrolyte, thereby mitigating the problem of decomposition due to reaction between the positive electrode active material and the solid electrolyte.

[0017] In some embodiments, the inorganic nanoparticles include one or more of nano-SiO2, nano-TiO2, nano-Al2O3, nano-MgO, nano-ZrO2, and nano-ZnO2.

[0018] Inorganic nanoparticles can promote gel formation during the preparation of gel electrolytes, allowing the gel electrolyte to be simultaneously distributed on the surface and inside the positive electrode active layer. Furthermore, these inorganic nanoparticles exhibit excellent stability, not reacting with other components of the gel electrolyte, nor with the solid electrolyte or positive electrode active material, during the gel formation process. This contributes to improving the structural stability of the battery and consequently enhancing its cycle performance.

[0019] In some embodiments, the first gel electrolyte and the second gel electrolyte also independently comprise electrolyte salts.

[0020] In some embodiments, the mass ratio of ionic liquid to polymer is 1:(0.2 to 2), and optionally 1:(0.4 to 1).

[0021] The mass ratio of ionic liquid to inorganic nanoparticles is 1:(0.005 to 0.1), and optionally 1:(0.01 to 0.1).

[0022] The mass ratio of ionic liquid to electrolyte salt is 1:(0.2-2), and optionally 1:(0.4-1).

[0023] By combining ionic liquids, polymers, inorganic nanoparticles, and electrolyte salts in appropriate proportions, gel electrolytes can achieve both a stable structure and high ion transport performance. This is beneficial for improving ion transport within the positive electrode and between the positive electrode and the solid electrolyte membrane, thereby enhancing battery capacity, initial efficiency, and cycle performance.

[0024] In some embodiments, the total content of the first gel electrolyte and the second gel electrolyte in the positive electrode layer is 1 mg / cm³. 2 ~3mg / cm 2 Optionally, it can be 1.5 mg / cm³. 2 ~2.5mg / cm 2 .

[0025] Adding this amount of gel electrolyte to the positive electrode can provide an ion transport channel that is not too long, effectively improving the battery's ion transport performance.

[0026] In some embodiments, the thickness of the second film layer is 0.5 μm to 3 μm, and optionally 1 μm to 2 μm.

[0027] By depositing a second film layer of this thickness on the surface of the positive electrode, the second gel electrolyte therein can fill the contact gap between the positive electrode and the solid electrolyte membrane, providing an ion transport path between the positive electrode and the solid electrolyte membrane. This short transport path is beneficial to improving the ion transport performance of the battery, thereby improving the battery capacity and cycle performance.

[0028] A second aspect of this application provides a positive electrode sheet, including a positive current collector and a positive electrode layer disposed on at least one side of the positive current collector. Along the direction away from the positive current collector, the positive electrode layer includes a first film layer and a second film layer stacked sequentially. The first film layer includes a positive active material and a first gel electrolyte, with the first gel electrolyte distributed between the positive active materials. The second film layer includes a second gel electrolyte.

[0029] The embodiments of this application can improve the battery's first efficiency and cycle performance by distributing gel electrolyte in both the first and second films of the positive electrode layer.

[0030] A third aspect of this application provides a method for preparing a positive electrode sheet, comprising:

[0031] A first film layer comprising a positive electrode active material is prepared on at least one side of the positive electrode current collector;

[0032] A gel electrolyte precursor solution is distributed on the surface and inside the first membrane layer;

[0033] The gel electrolyte precursor solution is subjected to gelation treatment, so that the gel electrolyte precursor solution forms a first gel electrolyte in the first membrane layer, and a second gel electrolyte forms on the surface of the first membrane layer.

[0034] In the preparation method of this application embodiment, a gel electrolyte precursor solution is distributed on the surface and inside of a first film layer including the positive electrode active material. During the gelation process, the gel electrolyte precursor solution on the surface and inside the first film layer can form a gel electrolyte. That is, a first gel electrolyte is formed in the first film layer, and a second gel electrolyte (second film layer) is formed on the surface of the first film layer. This structure can effectively improve ion transport inside the positive electrode sheet and between the positive electrode sheet and the solid electrolyte film, thereby promoting the battery capacity and enabling the battery to have high initial efficiency and good cycle performance.

[0035] In some embodiments, the gel electrolyte precursor solution includes ionic liquids, oligomers or polymer monomers, and inorganic nanoparticles.

[0036] In some embodiments, the Dv50 of the inorganic nanoparticles is 1 nm to 100 nm, and optionally 1 nm to 50 nm.

[0037] Adding inorganic nano-ions to the gel electrolyte precursor solution can promote gel formation during the preparation of the gel electrolyte, allowing the gel electrolyte to be distributed simultaneously on the surface and inside the positive electrode active layer (first film layer).

[0038] In some embodiments, the gel electrolyte precursor solution also includes an electrolyte salt.

[0039] In some embodiments, the preparation method of the gel electrolyte precursor solution includes:

[0040] A solution a containing an ionic liquid is mixed with a solution b containing oligomers or polymer monomers; the resulting mixture is then mixed with inorganic nanoparticles.

[0041] In some embodiments, the method of distributing the gel electrolyte precursor solution on the surface and inside the first membrane layer includes: coating the gel electrolyte precursor solution on the surface of the first membrane layer.

[0042] The coating amount of the gel electrolyte precursor solution was 5 mg / cm³. 2 ~15mg / cm 2 Optionally 8 mg / cm 2 ~12mg / cm 2 .

[0043] After coating the surface of the first membrane layer with the gel electrolyte precursor solution, some of the gel electrolyte precursor solution can penetrate into the interior of the first membrane layer, while some remains on the surface. Thus, during the subsequent gelation process, both the gel electrolyte precursor solution on the surface and inside the first membrane layer can form a gel electrolyte. That is, a first gel electrolyte is formed in the first membrane layer, while a second gel electrolyte (second membrane layer) is formed on the surface of the first membrane layer. This structure effectively improves ion transport both inside the positive electrode and between the positive electrode and the solid electrolyte membrane, thereby promoting battery capacity and resulting in high initial efficiency and excellent cycle performance.

[0044] In some embodiments, the gelation treatment method includes one or more of heat treatment, radiation treatment, and light treatment.

[0045] During heating, radiation, or light exposure, oligomers or polymer monomers undergo in-situ polymerization to form a network structure that encapsulates ionic liquids, inorganic nanoparticles, etc., forming a gel. Simultaneously, the solvent in the gel electrolyte precursor solution evaporates during heating, and the precursor solution gradually transforms from a liquid to a gel state.

[0046] This application also provides some related devices, including battery devices, energy storage devices, and power consumption devices.

[0047] The battery device includes multiple solid-state battery cells.

[0048] The solid-state battery cell of this application embodiment has high initial efficiency and good cycle performance. Therefore, applying the solid-state battery cell to a battery device is beneficial to improving the cycle performance of the battery device and extending the service life of the battery device.

[0049] Energy storage devices include multiple solid-state battery cells or multiple battery devices, which are used to store or provide electrical energy.

[0050] The aforementioned solid-state battery cells and battery devices with high initial efficiency and good cycle performance are used to store or provide electrical energy for energy storage devices, which can extend the service life of energy storage devices.

[0051] Electrical devices include multiple solid-state battery cells or multiple battery devices, which are used to store or provide electrical energy.

[0052] The aforementioned solid-state battery cells and battery devices with high initial efficiency 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

[0053] 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.

[0054] Figure 1 shows a schematic diagram of the structure of some solid-state batteries;

[0055] Figure 2 is a schematic diagram of the structure of the positive electrode sheet according to an embodiment of this application;

[0056] Figure 3 is a schematic diagram of the internal structure of the first membrane layer according to an embodiment of this application;

[0057] Figure 4 is a schematic diagram of a battery cell according to an embodiment of this application;

[0058] Figure 5 is an exploded view of a battery cell according to an embodiment of this application, as shown in Figure 4.

[0059] Reference numerals: 10-positive electrode, 11-positive current collector, 12-first membrane layer, 13-second membrane layer, 20-solid electrolyte membrane, 30-negative electrode; a-particles contained in the first membrane layer, b-first gel electrolyte; 01-shell, 02-cover plate, 03-electrode assembly. Detailed Implementation

[0060] 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.

[0061] 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.

[0062] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0063] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0064] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0065] 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.

[0066] 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).

[0067] Referring to Figure 1, in a solid-state battery, a solid electrolyte (usually used in the form of a film, referred to as solid electrolyte membrane 20) is disposed between the positive electrode 10 and the negative electrode 30. The solid electrolyte membrane and the positive electrode are in solid contact, which can lead to insufficient and uneven contact. To improve this problem, pressure is usually applied during the solid-state battery manufacturing process to improve the contact between the solid electrolyte membrane and the positive electrode. However, during repeated charge and discharge cycles, both the positive and negative electrodes undergo volume changes, which still deteriorates the interfacial contact between the solid electrolyte membrane and the positive electrode, causing increased battery impedance, increased polarization, and affecting battery capacity and cycle stability, such as lower initial efficiency and rapid capacity decline after cycling.

[0068] To address this, an ion-conducting membrane can be placed between the positive electrode and the solid electrolyte membrane, thus improving the interfacial contact between the two. However, even with this, the battery's initial efficiency and cycle performance are difficult to improve effectively.

[0069] The positive electrode typically comprises a positive electrode active material, a solid electrolyte, and components such as conductive agents and binders. The positive electrode active material and the solid electrolyte are in contact in a solid-solid manner; more specifically, the contact between the positive electrode active material particles and the solid electrolyte particles is usually point-to-point, resulting in insufficient and uneven contact. The solid electrolyte primarily provides ion conduction channels in the positive electrode, promoting ion conduction. Poor contact between the positive electrode active material and the solid electrolyte hinders ion conduction between them, leading to low ionic conductivity of the positive electrode, impaired battery capacity utilization, and insufficient battery cycle performance.

[0070] Based on this, the embodiments of this application provide a gel electrolyte on both the surface and inside of the positive electrode active layer of the solid-state battery cell, which can simultaneously improve the contact between materials inside the positive electrode sheet and the interfacial contact between the positive electrode sheet and the solid electrolyte membrane, thereby improving the battery's first efficiency and cycle performance.

[0071] The solid-state battery cell of this application embodiment includes a positive electrode, a negative electrode, and a solid electrolyte membrane. The solid electrolyte membrane is disposed between the positive and negative electrode and is in contact with both the positive and negative electrode. During the charging and discharging process of the battery, active ions are inserted and extracted back and forth between the positive and negative electrode, and the solid electrolyte membrane plays the role of conducting ions between the positive and negative electrode.

[0072] [Positive electrode plate]

[0073] In some embodiments, the structure of the positive electrode sheet can be referred to FIG2. The positive electrode sheet includes a positive current collector 11 and a positive electrode layer disposed on at least one side of the positive current collector 11. Along the direction away from the positive current collector 11, the positive electrode layer includes a first film layer 12 and a second film layer 13 stacked sequentially; the first film layer 12 includes a positive active material and a first gel electrolyte, the first gel electrolyte being distributed between the positive active materials; the second film layer 13 includes a second gel electrolyte.

[0074] Gel electrolytes, also known as gel-like electrolytes, are semi-solid electrolytes in which solid and liquid phases coexist, and typically possess good elasticity.

[0075] Along the direction away from the positive current collector, the positive electrode layer includes a first film layer and a second film layer stacked sequentially; that is, the first film layer is stacked on the surface of the positive current collector, and the second film layer is stacked on the surface of the first film layer. Along the direction away from the positive current collector, the positive electrode sheet sequentially includes a positive current collector, the first film layer, and the second film layer. This structure can be analyzed using a high-magnification electron microscope combined with infrared spectroscopy.

[0076] The first membrane layer includes the positive electrode active material; that is, the first membrane layer is a traditional positive electrode active layer. The first gel electrolyte is distributed between the positive electrode active materials, meaning that the first gel electrolyte is distributed between the particles of the positive electrode active materials, and the first gel electrolyte and the positive electrode active materials are in a mixed state. The first membrane layer includes the first gel electrolyte, and the second membrane layer includes the second gel electrolyte, meaning that gel electrolytes are distributed both inside and on the surface of the positive electrode active layer.

[0077] The embodiments of this application improve the battery's initial efficiency and cycle performance by distributing gel electrolyte in both the first and second films of the positive electrode layer. The mechanism of action is as follows:

[0078] Referring to Figure 3, in the first film layer, the first gel electrolyte b can fill the voids between the particles a (including the positive electrode active material, and optionally also a conductive agent or other materials) contained in the first film layer, reducing the voids in the positive electrode layer, providing a path for ion transport between particles, and improving the ion transport performance inside the positive electrode sheet. Simultaneously, the second gel electrolyte in the second film layer can serve as an interface modification layer between the positive electrode sheet and the solid electrolyte membrane of the battery, filling the interface gaps between the positive electrode sheet and the solid electrolyte membrane, compensating for the gaps caused by solid-solid contact, effectively improving the solid-solid contact problem that occurs between the positive electrode sheet and the solid electrolyte membrane during charging and discharging, providing a path for ion transport between the positive electrode sheet and the solid electrolyte membrane, and improving the ion transport performance between the positive electrode sheet and the solid electrolyte membrane. Therefore, by distributing gel electrolytes in both the first and second film layers of the positive electrode layer, ion transport inside the positive electrode sheet and between the positive electrode sheet and the solid electrolyte membrane can be effectively improved simultaneously, thereby benefiting the battery capacity and enabling the battery to have high initial efficiency and good cycle performance.

[0079] In some embodiments, the first gel electrolyte and the second gel electrolyte are in contact with each other at the interface between the first and second membrane layers. That is, at the interface between the first and second membrane layers, the first gel electrolyte and the second gel electrolyte are continuous without a clear boundary, forming a single integrated structure. This allows for smooth ion transport between the first and second membrane layers and the solid electrolyte membrane, improving the ionic conductivity of the positive electrode, thereby facilitating the battery's capacity utilization and enhancing its initial efficiency and cycle performance.

[0080] In some embodiments, the first gel electrolyte and the second gel electrolyte independently comprise an ionic liquid, a polymer, and inorganic nanoparticles, respectively. Optionally, the first gel electrolyte and the second gel electrolyte have the same composition.

[0081] The components in the first and second gel electrolytes can be analyzed and identified using infrared spectroscopy, nuclear magnetic resonance, and mass spectrometry.

[0082] This type of gel electrolyte is an ionic liquid gel electrolyte with excellent ion transport performance, which is beneficial to improving the ionic conductivity inside and on the surface of the positive electrode, thereby improving the battery's initial efficiency and cycle life.

[0083] Ionic liquids are room-temperature (20℃~25℃) organic molten salts composed of organic cations and organic or inorganic anions. They typically possess high ionic conductivity, enabling ion transport within the positive electrode and between the positive electrode and the solid electrolyte. Polymers, serving as the framework of the gel electrolyte, can encapsulate the ionic liquid, forming an ionic liquid gel electrolyte. Inorganic nanoparticles can promote gel formation during the preparation of the gel electrolyte, allowing the gel electrolyte to be simultaneously distributed on the surface and within the positive electrode active layer.

[0084] In some embodiments, the anion contained in the ionic liquid includes bis(fluorosulfonyl)imide anion (FSI). - ), bis(trifluoromethanesulfonyl)imide anion (TFSI) - ), trifluoromethanesulfonic acid anion (OTf) - One or more of the following.

[0085] The cations contained in ionic liquids include one or more of the following: pyrrolidine cations, imidazole cations, piperidine cations, pyridine cations, and thiophene cations.

[0086] Among them, pyrrolidine cations include one or more of N-alkyl-N-methylpyrrolidine cations and N-alkyl-N-propylpyrrolidine cations.

[0087] Imidazole cations include one or more of 1-alkylimidazolium cations, 1-alkyl-3-methylimidazolium cations, and 1-alkyl-2,3-dimethylimidazolium cations.

[0088] Piperidine cations include one or more of N-alkyl-N-methylpiperidine cations and N-alkyl-N-propylpiperidine cations.

[0089] Pyridine cations include N-alkylpyridine cations.

[0090] Thiophene cations include thiophene methyl ammonium chloride cations.

[0091] The alkyl group may include one or more of the following: methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl.

[0092] Exemplary cations include 1-ethyl-3-methylimidazolium cation (EMIM). + ), 1-Butyl-3-methylimidazolium cation (BMIM) + ), N-methyl-N-propylpyrrolidine cation (Pyr13) + ), N-methyl-N-propylpiperidine cation (PP13) + One or more of the following.

[0093] Exemplary ionic liquids include one or more of N-methyl-N-propylpiperidine di(trifluoromethanesulfonyl)imide (PP13TFSI), 1-methyl-1-propylpyrrolidine bis(trifluoromethanesulfonyl)imide (Pyr13TFSI), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIMTFSI), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIMTFSI), and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM]OTf).

[0094] These ionic liquids exhibit excellent stability and ionic conductivity, and do not react with common solid electrolytes. This is beneficial for improving ion transport performance inside and on the surface of the positive electrode, and maintaining battery structural stability. Typically, in cases where the solid electrolyte includes a sulfide solid electrolyte, the ionic liquids in the embodiments of this application are halogen-free, thus maintaining stability between the ionic liquid and the solid electrolyte without reaction.

[0095] In some embodiments, the polymer includes one or more of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), nitrile rubber (NBR), saturated ester polymers, polyacrylonitrile (PAN), polyethylene oxide (PEO), polypropylene oxide (PPO), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and polyvinylidene fluoride (PVDF). The saturated ester polymers include one or more of polyester resins, polyesteramides, and polyether ester amides.

[0096] The weight-average molecular weight of the polymer is 200,000 to 600,000, optionally 300,000 to 500,000, for example, any one of 200,000, 250,000, 300,000, 350,000, 400,000, 450,000, 500,000, 550,000, 600,000 or any range between two.

[0097] The weight-average molecular weight of polymers can be obtained by mass spectrometry.

[0098] These high molecular weight polymers utilize their long molecular chain segments to form cross-linked network structures, encapsulating components such as ionic liquids and inorganic nanoparticles to form gels. Furthermore, these polymers possess excellent stability, and the gel electrolyte formed using them as a framework fills the interface gaps between the positive electrode and the solid electrolyte. This protects the positive electrode active material in the positive electrode from direct contact with the solid electrolyte, thereby mitigating the problem of decomposition due to reaction between the positive electrode active material and the solid electrolyte.

[0099] In some embodiments, the inorganic nanoparticles include one or more of nano-SiO2, nano-TiO2, nano-Al2O3, nano-MgO, nano-ZrO2, and nano-ZnO2. These inorganic nanoparticles exhibit excellent stability and do not react with other components of the gel electrolyte during the gel formation process, nor with solid electrolytes, positive electrode active materials, etc., which is beneficial to improving the structural stability of the battery and thus improving the battery cycle performance.

[0100] In some embodiments, the first gel electrolyte and the second gel electrolyte also independently comprise electrolyte salts. The electrolyte salts can provide metal ions, which facilitates ion conduction.

[0101] The appropriate electrolyte salt can be selected according to the battery type. For example, for lithium-ion batteries, the electrolyte salt includes lithium salt, and for sodium-ion batteries, the electrolyte salt includes sodium salt.

[0102] For example, electrolyte salts include one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiOTf), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate borate) (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0103] Optionally, the electrolyte salt may include the same anions as the ionic liquid, thereby improving the compatibility between the electrolyte salt and the ionic liquid.

[0104] In some embodiments, the mass ratio of ionic liquid to polymer is 1:(0.2 to 2), optionally 1:(0.4 to 1), for example, it can be any one of 1:0.2, 1:0.4, 1:0.5, 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2 or any range between the two.

[0105] The mass ratio of ionic liquid to inorganic nanoparticles is 1:(0.005 to 0.1), optionally 1:(0.01 to 0.1), for example, any one of the following values ​​or any range between 1:0.005, 1:0.01, 1:0.02, 1:0.04, 1:0.06, 1:0.08, 1:0.1.

[0106] The mass ratio of ionic liquid to electrolyte salt is 1:(0.2 to 2), optionally 1:(0.4 to 1), for example, it can be any one of the following values ​​or any range between the two: 1:0.2, 1:0.4, 1:0.5, 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2.

[0107] Thermogravimetric analysis (e.g., TG-DSC), mass spectrometry, or nuclear magnetic resonance (NMR) can be used to analyze the proportions of each component. Combining ionic liquids, polymers, inorganic nanoparticles, and electrolyte salts in appropriate proportions can give the gel electrolyte a stable structure and high ion transport performance. This improves ion transport within the positive electrode and between the positive electrode and the solid electrolyte membrane, thereby enhancing battery capacity and improving initial efficiency and cycle performance.

[0108] In some embodiments, the total content of the first gel electrolyte and the second gel electrolyte in the positive electrode layer is 1 mg / cm³. 2 ~3mg / cm 2 Optionally, it can be 1.5 mg / cm³. 2 ~2.5mg / cm 2 For example, 1 mg / cm 2 1.2 mg / cm 2 1.4 mg / cm 2 1.6 mg / cm 2 1.8 mg / cm 2 2mg / cm 2 14mg / cm 2 2.2 mg / cm 2 2.4 mg / cm 2 2.6 mg / cm 2 2.8 mg / cm 2 3mg / cm 2 The value of any one of the points or the range between any two.

[0109] Thermogravimetric analysis (e.g., TG-DSC) can be used to analyze the content of gel electrolyte in the positive electrode. Adding this amount of gel electrolyte to the positive electrode can provide ion transport channels that are not too long, effectively improving the ion transport performance of the battery.

[0110] In some embodiments, the thickness of the second film layer is 0.5 μm to 3 μm, optionally 1 μm to 2 μm, for example, it can be any one of 0.5 μm, 1 μm, 1.2 μm, 2 μm, 2.5 μm, 3 μm or any range between two.

[0111] The thickness of the second film layer can be observed and measured using a high-magnification electron microscope. The thickness of the second film layer can also be understood as the thickness of the second gel electrolyte. By depositing this thickness of second film layer on the surface of the positive electrode, the second gel electrolyte within it can fill the contact gap between the positive electrode and the solid electrolyte membrane, providing a short ion transport path between them. This, in turn, improves the battery's ion transport performance, capacity, and cycle performance.

[0112] In some embodiments, the thickness of the first film layer is 5 μm to 50 μm, optionally 10 μm to 30 μm, for example, any one of 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or a range between any two.

[0113] The thickness of the first film layer can be observed and measured using a high-magnification electron microscope. The thickness of the second film layer in this embodiment can be designed as needed, and is not limited to the thickness range listed above. For example, the required mass of the positive electrode active material in the first film layer can be determined according to the designed capacity; the thickness of the first film layer varies with different masses of the positive electrode active material. The first film layer includes the positive electrode active material and the first gel electrolyte, which are in a mixed state. Therefore, the first gel electrolyte is usually distributed throughout the thickness range of the first film layer. Optionally, the first gel electrolyte is uniformly distributed in the thickness direction of the first film layer. Optionally, the concentration of the first gel electrolyte in the first film layer gradually increases along the direction away from the positive electrode current collector. In different states, the first gel electrolyte can be used to fill the gaps between particles in the positive electrode sheet, improving ion transport within the positive electrode sheet.

[0114] 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, wherein carbon can serve as a coating layer for the relevant composite material. Examples of lithium transition metal oxides may include lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), 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 Co0.2 Mn 0.3 O2(NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 O2), lithium niobium oxides (such as lithium niobate), lithium titanium oxides (such as Li4Ti5O) 12 One or more of the following: and their modified compounds. These positive electrode active materials can be used alone or in combination of two or more. The mass content of the positive electrode active material can include 60% to 98%, for example, any one of 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98%, or a range between any two. Here, the mass content of the positive electrode active material refers to: mass of the positive electrode active material / (total mass of the first membrane layer - mass of the first gel electrolyte).

[0115] The solution of this application embodiment is applicable to various positive electrode active materials. The positive electrode active material and the first gel electrolyte are in a mixed state. The first gel electrolyte fills the spaces between the particles of the positive electrode active material, improving ion transport between the particles.

[0116] In some embodiments, the first film layer further includes a conductive agent. The conductive agent may include one or more of 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 may be 0.5% to 5%, for example, it may be any one of 0.5%, 1%, 1.5%, 2%, 3%, 4%, and 5%, or a range between any two. Here, the mass content of the conductive agent refers to: mass of conductive agent / (total mass of the first film layer - mass of the first gel electrolyte).

[0117] In some embodiments, the first membrane layer further includes an adhesive. The adhesive may include one or more of the following: nitrile rubber (NBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-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 adhesive may be 0.5% to 5%, for example, any one of 0.5%, 1%, 1.5%, 2%, 3%, 4%, and 5%, or a range between any two. Here, the mass content of the adhesive refers to: mass of adhesive / (total mass of the first membrane layer - mass of the first gel electrolyte).

[0118] 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.].

[0119] In some embodiments, the first film layer may optionally include a solid electrolyte. The solid electrolyte includes one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer solid electrolytes, and optionally includes a sulfide solid electrolyte. 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.

[0120] Understandably, the first gel electrolyte in this embodiment can replace a commonly used solid electrolyte; therefore, the first membrane layer in this embodiment may not include a solid electrolyte. Of course, a small amount of solid electrolyte may be added as needed. Even when the first membrane layer includes a solid electrolyte, the first gel electrolyte in this embodiment can still be used to fill the gaps between the positive electrode active material and the solid electrolyte particles, improving the solid-solid contact between the particles.

[0121] The positive electrode sheet can be prepared by the following method:

[0122] S1: A first film layer comprising a positive electrode active material is prepared on at least one side of the positive electrode current collector;

[0123] S2: Gel electrolyte precursor solution is distributed on the surface and inside the first membrane layer;

[0124] S3: The gel electrolyte precursor solution is gelled to form a first gel electrolyte in the first membrane layer and a second gel electrolyte on the surface of the first membrane layer.

[0125] Among them, the gel electrolyte precursor solution is a liquid capable of forming a gel electrolyte. Gelification treatment of the gel electrolyte precursor solution refers to gradually making the precursor solution viscous, eventually causing it to lose its fluidity and form an elastic gel.

[0126] In the preparation method of this application embodiment, a gel electrolyte precursor solution is distributed on the surface and inside of a first film layer including the positive electrode active material. During the gelation process, the gel electrolyte precursor solution on the surface and inside the first film layer can form a gel electrolyte. That is, a first gel electrolyte is formed in the first film layer, and a second gel electrolyte (second film layer) is formed on the surface of the first film layer. This structure can effectively improve ion transport inside the positive electrode sheet and between the positive electrode sheet and the solid electrolyte film, thereby promoting the battery capacity and enabling the battery to have high initial efficiency and good cycle performance.

[0127] In some embodiments, step S1, the method for preparing the first film layer includes: mixing components used to prepare the first film layer, such as a positive electrode active material, a conductive agent, a binder, and any other components, to prepare a positive electrode slurry; coating the positive electrode slurry onto at least one side of the positive electrode current collector; and forming the first film layer after drying.

[0128] In some embodiments, in step S2, the gel electrolyte precursor solution includes ionic liquids, oligomers or polymer monomers, and inorganic nanoparticles.

[0129] Oligomers or polymer monomers:

[0130] Oligomers refer to incompletely polymerized low-molecular-weight polymers composed of a few repeating units. They are reactive and can undergo polymerization reactions to form polymers with higher molecular weights. Polymer monomers refer to small molecules that can polymerize with the same or other types of molecules to form polymers. The polymer monomers in the embodiments of this application can be a single type or multiple types. That is, when the gel electrolyte precursor solution contains polymer monomers, it can include one type of polymer monomer or multiple different polymer monomers. The gel electrolyte precursor solution in the embodiments of this application includes oligomers or polymer monomers. The oligomers or polymer monomers can form a network structure through polymerization reactions or other pathways to encapsulate ionic liquids, inorganic nanoparticles, etc., to form a gel.

[0131] Different oligomers or polymer monomers can be used as raw materials for different polymers. For example, when the polymer includes polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinylidene fluoride-hexafluoropropylene oligomers or polyvinylidene fluoride monomers or hexafluoropropylene monomers can be used. For example, when the polymer includes polyacrylonitrile (PAN), polyacrylonitrile oligomers or acrylonitrile monomers can be used. For example, when the polymer includes polyethylene oxide (PEO), polyethylene oxide oligomers or ethylene oxide monomers can be used.

[0132] In some embodiments, the weight-average molecular weight of the oligomer is 100–600, optionally 200–400, for example, any point value or a range between 100, 200, 300, 400, 500, and 600. The weight-average molecular weight of the oligomer can be obtained by methods such as viscosity analysis or light scattering. For example, the sample can be dissolved in a suitable solvent, the viscosity or refractive index of the solution can be measured, and the weight-average molecular weight can be calculated using the viscosity or refractive index. These oligomers are highly reactive and can form a network structure through polymerization, encapsulating ionic liquids, inorganic nanoparticles, etc., to form a gel.

[0133] Inorganic nanoparticles:

[0134] Inorganic nanoparticles can promote the gelation of gel electrolyte precursor solutions, enabling gel electrolyte precursor solutions distributed inside the first membrane layer to also form gels (in the absence of inorganic nanoparticles, gel electrolyte precursor solutions usually need to be coated on the surface of a certain substrate to form gels, and are difficult to gel after being distributed inside the first membrane layer).

[0135] In some embodiments, the Dv50 of inorganic nanoparticles is 1 nm to 100 nm, optionally 1 nm to 50 nm, for example, any point value or range between any two of 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, and 100 nm. The particle size distribution of materials is usually expressed as the percentage of particles within different particle size ranges. There are various benchmarks for measuring 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 / ISO13320:2009 "Particle size distribution - Laser diffraction method".

[0136] Adding inorganic nano-ions to the gel electrolyte precursor solution can promote gel formation during the preparation of the gel electrolyte, allowing the gel electrolyte to be distributed simultaneously on the surface and inside the positive electrode active layer (first film layer).

[0137] In some embodiments, step S2 further includes an electrolyte salt in the gel electrolyte precursor solution.

[0138] In some embodiments, step S2 may optionally include an initiator and a crosslinking agent in the gel electrolyte precursor solution. The initiator and crosslinking agent can promote the polymerization reaction of oligomers or polymer monomers in the gel electrolyte precursor solution to form a gel. It is understood that the gel electrolyte precursor solution may not contain an initiator or crosslinking agent. The gel electrolyte precursor solution can also form a gel even without an initiator or crosslinking agent.

[0139] In some embodiments, step S2, the preparation method of the gel electrolyte precursor solution includes:

[0140] A solution a containing an ionic liquid is mixed with a solution b containing oligomers or polymer monomers; the resulting mixture is then mixed with inorganic nanoparticles.

[0141] More specifically, an ionic liquid and an electrolyte salt are mixed to obtain solution a;

[0142] Solution b, containing oligomers or polymer monomers, is mixed with solution a, and the resulting mixed solution is then mixed with inorganic nanoparticles.

[0143] This application describes a method to obtain the desired gel electrolyte precursor solution by sequentially mixing the various materials. During the mixing process, the inorganic nanoparticles are added in the final step, thus preventing premature gelation during the preparation of the gel electrolyte precursor solution.

[0144] The ionic liquid and electrolyte salt are mixed and then subjected to ultrasonic treatment at 10℃~35℃ (e.g., any one of 10℃, 15℃, 20℃, 25℃, 30℃, 35℃ or any range between two) for 10min~60min, e.g., any one of 10min, 20min, 30min, 40min, 50min, 60min or any range between two) to promote the mixing of the ionic liquid and electrolyte salt.

[0145] Solution b contains a solvent, which may include one or more of acetone, dimethyl oxalate, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and toluene. These solvents can effectively disperse or dissolve oligomers or polymer monomers, facilitating the mixing of oligomers or polymer monomers with other materials, thereby forming a homogeneous gel electrolyte in the subsequent process.

[0146] The concentration of the oligomer or polymer monomer in solution b can be 0.01 g / mL to 0.1 g / mL, for example, any one of 0.01 g / mL, 0.02 g / mL, 0.04 g / mL, 0.05 g / mL, 0.06 g / mL, 0.08 g / mL, or 0.1 g / mL, or any range between two values. The oligomer or polymer monomer can be mixed with a solvent and ultrasonically treated at 30°C to 60°C (e.g., any one of 30°C, 40°C, 50°C, or 60°C, or any range between two values) for 10 min to 5 h, for example, 10 min, 30 min, 60 min, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, or any range between two values) to obtain solution b.

[0147] In some embodiments, step S2, the method of distributing the gel electrolyte precursor solution on the surface and inside the first membrane layer, includes: coating the gel electrolyte precursor solution onto the surface of the first membrane layer. The coating method includes one or more of spraying, brushing, and dipping. The coating amount of the gel electrolyte precursor solution can be set as needed, for example, a coating amount of 5 mg / cm³. 2 ~15mg / cm 2 Optionally 8 mg / cm 2 ~12mg / cm 2 For example, 5mg / cm 2 6mg / cm 28mg / cm 2 10mg / cm 2 12mg / cm 2 14mg / cm 2 15mg / cm 2 The value of any one of the points or the range between any two.

[0148] After coating the surface of the first membrane layer with the gel electrolyte precursor solution, some of the gel electrolyte precursor solution can penetrate into the interior of the first membrane layer, while some remains on the surface. Thus, during the subsequent gelation process, both the gel electrolyte precursor solution on the surface and inside the first membrane layer can form a gel electrolyte. That is, a first gel electrolyte is formed in the first membrane layer, while a second gel electrolyte (second membrane layer) is formed on the surface of the first membrane layer. This structure effectively improves ion transport both inside the positive electrode and between the positive electrode and the solid electrolyte membrane, thereby promoting battery capacity and resulting in high initial efficiency and excellent cycle performance.

[0149] In some embodiments, the gelation treatment in step S3 includes one or more of heating treatment, radiation treatment, and light treatment. For example, heating can be used, and the heating temperature can be 50℃ to 100℃, optionally 60℃ to 80℃, for example, any one of 50℃, 60℃, 70℃, 80℃, 90℃, and 100℃, or a range between any two. The heating time can be 5h to 15h, optionally 8h to 12h, for example, any one of 5h, 6h, 7h, 8h, 9h, 10h, 12h, 14h, and 15h, or a range between any two.

[0150] During heating, radiation, or light exposure, oligomers or polymer monomers undergo in-situ polymerization to form a network structure that encapsulates ionic liquids, inorganic nanoparticles, etc., forming a gel. Simultaneously, the solvent in the gel electrolyte precursor solution evaporates during heating, and the gel electrolyte precursor solution gradually transforms from a liquid state to a gel state.

[0151] In some embodiments, a compaction step is included after step S3. The compaction process can use pressures ranging from several MPa to tens of MPa, for example, 5 MPa to 60 MPa, optionally 10 MPa to 25 MPa, such as any one of 5 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, and 60 MPa, or a range between any two.

[0152] Compaction treatment can increase the density of the first film layer, promote the contact between the first gel electrolyte and the positive electrode active material particles in the first film layer, and improve ion transport inside the positive electrode sheet; it also helps to improve the energy density of the battery.

[0153] [Negative electrode plate]

[0154] In some embodiments, the negative electrode sheet of this application includes one or more of metallic lithium, lithium alloys, and carbon materials, wherein the lithium alloy includes one or more of lithium-indium alloys, lithium-silicon alloys, lithium-tin alloys, and lithium-aluminum alloys. The carbon material may include one or more of graphite, soft carbon, hard carbon, and carbon-metal composite materials (e.g., Ag-C composite materials). Metallic lithium, lithium alloys, and carbon materials can be directly used as the negative electrode sheet.

[0155] In some embodiments, the negative electrode sheet includes a negative current collector and a negative active layer disposed on at least one side of the negative current collector, the negative active layer including a negative active material, a conductive agent, and a binder.

[0156] In some embodiments, the negative electrode active material includes one or more of graphite (artificial graphite, natural graphite), soft carbon, hard carbon, silicon-based materials, tin-based materials, and titanium-based materials. Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide compounds, and tin alloys. Titanium-based materials may include lithium titanate. It is understood that this application is not limited to these materials, and other materials that can be used as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0157] The mass content of the negative electrode active material in the negative electrode active layer can be 70% to 98%, or 90% to 98%, for example, any one of the values ​​of 70%, 75%, 80%, 85%, 90%, 92%, 94%, 96%, 98%, or any range between two.

[0158] In some embodiments, the conductive agent in the negative electrode active layer may include one or more of 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 0.5% to 5%, for example, it may be any one of 0.5%, 1%, 2%, 3%, 4%, and 5%, or any range between two values.

[0159] In some embodiments, the binder in the negative electrode active layer may include one or more of 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 0.001% to 2%, for example, any one of 0.001%, 0.01%, 0.1%, 0.5%, 1%, or 2%, or a range between any two.

[0160] In some embodiments, the negative electrode current collector includes two surfaces opposite each other in its own thickness direction, and the negative electrode active layer can be disposed on either or both of the 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, 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.].

[0161] In some implementations, the negative electrode sheet can be prepared in the following manner:

[0162] The components used to prepare the negative electrode sheet, such as the negative electrode active material, binder, and conductive agent (which may also include any other components), are dispersed in a solvent (e.g., water) to form a negative electrode slurry. The negative electrode slurry is coated on at least one side of the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0163] [Solid electrolyte]

[0164] 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.

[0165] The solid electrolyte membrane in this application includes one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer solid electrolytes, and optionally includes sulfide solid electrolytes. Sulfide solid electrolytes include one or more of Li6PS5Cl, Li2S-GeS2, Li2S-P2S5, Li2S-SiS2, and Li2S-MeS2-P2S5 (Me = Si, Ge, Sn, Al, etc.). Halide solid electrolytes include one or more of Li3YCl6, Li3InCl6, Li3ErCl6, Li3ScCl6, Li3HoCl6, Li2MnCl4, Li2MnCl5, and Li6FeCl8. Oxide solid electrolytes include lithium oxide garnet (Li7La3Zr2O). 12 This includes one or more of the following: LLZO, tin oxide (SnO2), and bismuth oxide (Bi2O3). Polymer solid electrolytes include one or more of the following: polyethylene oxide electrolytes, polycarbonate electrolytes, and polysiloxane electrolytes.

[0166] The Dv50 of the solid electrolyte is 1μm to 10μm, for example, any point value or a range between any two of 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, and 10μm.

[0167] Solid electrolyte membranes can be prepared by the following method:

[0168] 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).

[0169] Alternatively, during battery assembly, solid electrolyte powder can be placed between the negative and positive electrode plates, and pressure can be applied to assemble the battery. At the same time, the solid electrolyte changes from a powder state to a film.

[0170] [Outer Packaging]

[0171] Solid-state battery cells may include an outer packaging that can be used to encapsulate the positive electrode, negative electrode, and solid electrolyte membrane.

[0172] 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.

[0173] The outer packaging can be cylindrical, square, or any other shape. For example, Figure 4 shows a solid-state battery cell with a square outer packaging structure as an example.

[0174] Referring to Figure 5, 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 may be stacked to form an electrode assembly 03. One or more electrode assemblies 03 are encapsulated within the receiving cavity.

[0175] [Solid-state battery cell]

[0176] In this embodiment, the solid-state battery cell can be a rechargeable battery, which refers to a battery cell that can be recharged after discharge to reactivate its active materials and continue to be used. Optionally, the solid-state battery cell in this embodiment is an all-solid-state battery, and more specifically, an all-solid-state lithium-ion battery. Of course, the solid-state battery cell can also be an all-solid-state sodium-ion battery.

[0177] The solid-state battery cell in this application includes the above-mentioned positive electrode sheet. The interior and surface of the positive electrode sheet have high ion conductivity, which can reduce battery resistance and fully utilize the capacity of the positive electrode sheet. Therefore, the battery containing the positive electrode sheet exhibits high first-efficiency and improved cycle performance.

[0178] Solid-state battery cells can be assembled as follows: stack them in the order of negative electrode plate - solid electrolyte membrane - positive electrode plate.

[0179] Because the surface of the positive electrode in this embodiment includes a second gel electrolyte, which can fill the interfacial gap between the positive electrode and the solid electrolyte membrane, and the second gel electrolyte itself has a certain viscosity, it can reduce the pressure required for the solid battery to maintain its performance. Therefore, during the assembly process, the battery can be assembled without applying pressure after the components are stacked. After stacking in the order of negative electrode - solid electrolyte membrane - positive electrode, the electrode assembly including the negative electrode, solid electrolyte membrane, and positive electrode can be encapsulated in a housing, which can ensure good contact performance between the positive electrode and the solid electrolyte membrane, and maintain good interfacial contact during charging and discharging.

[0180] Of course, pressure can also be applied after stacking during battery assembly.

[0181] Alternatively, the materials can be added into the mold in the order of "negative electrode - solid electrolyte (powder) - positive electrode", and pressure can be applied to compact each time a new material is added into the mold.

[0182] [Battery Device]

[0183] 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 battery cell assembly may include multiple solid-state battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0184] The solid-state battery cell of this application embodiment has high initial efficiency and good cycle performance. Therefore, applying the battery cell to a battery device is beneficial to improving the cycle performance of the battery device and extending the service life of the battery device.

[0185] In some implementations, a battery cell assembly is typically formed by arranging multiple battery cells.

[0186] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0187] 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.

[0188] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0189] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] The technical solutions described in the embodiments of this application are applicable to various battery 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.

[0194] [Energy Storage Device]

[0195] 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.

[0196] The aforementioned solid-state battery cells and battery devices with high initial efficiency and good cycle performance are used to store or provide electrical energy for energy storage devices, which can extend the service life of energy storage devices.

[0197] 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.

[0198] 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.

[0199] In some implementations, the energy storage device is an energy storage container or an energy storage cabinet.

[0200] In some implementations, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0201] 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.

[0202] 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.

[0203] 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 a slave battery management unit (SBMU), a fusion switch, and other modules.

[0204] 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.

[0205] 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.

[0206] As an example, a power distribution module can be used to distribute power to modules in an energy storage device that require electricity.

[0207] [Electrical appliances]

[0208] This application provides an electrical 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.

[0209] The aforementioned solid-state battery cells and battery devices with high initial efficiency and good cycle performance can be used as power sources for electrical devices or as energy storage units for electrical devices, thereby extending the service life of electrical devices.

[0210] 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.

[0211] 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.

[0212] Example 1

[0213] 1. Positive electrode plate

[0214] Weigh 1.0g of ionic liquid BMIMFSI and 0.5g of lithium salt LiFSI, and sonicate at room temperature (20℃~25℃) for 30 minutes to form solution a. Weigh 0.5g of polyvinylidene fluoride-hexafluoropropylene copolymer (weight average molecular weight of 200~400), place it in 10mL of acetone, and sonicate at 50℃ for 3 hours to form solution b. Mix the above solutions a and b, and then add 0.040g of nano-SiO2 particles (particle size Dv50 of about 2nm), and stir at 50℃ for 3 hours to form solution c, which is the ionic liquid gel electrolyte precursor solution.

[0215] The positive electrode active material NCM811, the conductive agent VGCF, and the binder NBR were dissolved in toluene at a mass ratio of 97:1.5:1.5 to obtain a positive electrode slurry. The positive electrode slurry was coated on aluminum foil and then dried to obtain a positive electrode sheet (approximately 20 μm thick).

[0216] Solution c was sprayed onto the surface of the pre-fabricated positive electrode sheet at a coating density of 10 mg / cm². 2 The vacuum oven is kept at 80°C for 10 hours, followed by cold pressing.

[0217] High-magnification electron microscopy revealed that the surface of the obtained positive electrode sheet was a film layer (second film layer) containing gel electrolyte, with a thickness of 1 μm to 2 μm; at the same time, gel electrolyte was also distributed in the positive electrode active layer (first film layer).

[0218] 2. Negative electrode plate

[0219] Li-In alloy is used as the negative electrode.

[0220] 3. Solid electrolyte

[0221] Li6PS5Cl solid electrolyte was used.

[0222] 4. Battery assembly

[0223] The cells are stacked in the order of "negative electrode - solid electrolyte - positive electrode" and then wound to obtain a bare cell. The bare cell is then welded with tabs and installed in an aluminum shell. After sealing, the cells undergo processes such as standing, hot pressing, formation, and capacity testing to obtain a solid-state battery.

[0224] Example 2

[0225] The difference between this embodiment and Embodiment 1 is that, in the process of preparing the positive electrode sheet, nano-SiO2 is replaced with an equal mass of nano-TiO2 (particle size Dv50 approximately 5 nm).

[0226] Example 3

[0227] The difference between this embodiment and Embodiment 1 is that, in the process of preparing the positive electrode, the ionic liquid BIMIFSI is replaced with an equal mass of PP13TFSI.

[0228] Example 4

[0229] The difference between this embodiment and Embodiment 1 is that, during the preparation of the positive electrode, the amount of solution c sprayed onto the surface of the positive electrode is 5 mg / cm². 2 .

[0230] Example 5

[0231] The difference between this embodiment and Embodiment 1 is that, during the preparation of the positive electrode, the amount of solution c sprayed onto the surface of the positive electrode is 15 mg / cm². 2 .

[0232] Comparative Example 1

[0233] The difference between this comparative example and Example 1 is that solution c was not sprayed onto the surface of the positive electrode during the preparation of the positive electrode sheet. Specifically, the preparation method of the positive electrode sheet in this comparative example is as follows: the positive active material NCM811, the conductive agent VGCF, and the binder NBR are dissolved in toluene at a mass ratio of 97:1.5:1.5 to obtain a positive electrode slurry. The positive electrode slurry is then coated onto aluminum foil, dried, and cold-pressed to obtain the positive electrode sheet.

[0234] Comparative Example 2

[0235] The difference between this comparative example and Example 1 is that solution c does not contain nano-SiO2 during the preparation of the positive electrode sheet.

[0236] The preparation method of the positive electrode sheet in this comparative example is as follows:

[0237] Weigh 1.0g of ionic liquid BMIMFSI and 0.5g of lithium salt LiFSI, and sonicate at room temperature for 30 minutes to form solution a. Weigh 0.5g of polyvinylidene fluoride-hexafluoropropylene copolymer, place it in 10mL of acetone, and sonicate at 50℃ for 3 hours to form solution b. Mix solution a and solution b, and stir at 50℃ for 3 hours to form solution c.

[0238] The positive electrode active material NCM811, the conductive agent VGCF, and the binder NBR were dissolved in toluene at a mass ratio of 97:1.5:1.5 to obtain a positive electrode slurry. The positive electrode slurry was coated on aluminum foil and then dried to obtain a positive electrode sheet.

[0239] Solution c was sprayed onto the surface of the pre-fabricated positive electrode sheet at a coating density of 10 mg / cm². 2 The vacuum oven is kept at 80°C for 10 hours, followed by cold pressing.

[0240] High-magnification electron microscopy revealed that the surface of the obtained positive electrode sheet was a film containing gel electrolyte; the gel electrolyte was difficult to observe in the positive electrode active layer.

[0241] Comparative Example 3

[0242] The difference between this comparative example and Example 1 is that, during the preparation of the positive electrode sheet, solution c was not sprayed onto the surface of the positive electrode sheet; at the same time, an ionic liquid gel was prepared separately for battery assembly.

[0243] Specifically, the preparation method of the positive electrode sheet in this comparative example is as follows: the positive active material NCM811, the conductive agent VGCF, and the binder NBR are dissolved in toluene at a mass ratio of 97:1.5:1.5 to obtain a positive electrode slurry. The positive electrode slurry is coated on aluminum foil and then dried to obtain a positive electrode sheet.

[0244] In addition, 1.0 g of ionic liquid BMIMFSI and 0.5 g of lithium salt LiFSI were weighed and sonicated at room temperature for 30 minutes to form solution a. 0.5 g of polyvinylidene fluoride-hexafluoropropylene copolymer (weight-average molecular weight 200–400) was weighed and placed in 10 mL of acetone, sonicated at 50°C for 3 hours to form solution b. Solutions a and b were mixed, and then 0.040 g of nano-SiO2 particles (particle size Dv50 of 2 nm–5 nm) were added. The mixture was stirred at 50°C for 3 hours to form solution c. Solution c was then coated onto the surface of a substrate (coating amount 10 mg / cm²). 2 The mixture was dried in a vacuum oven at 80°C for 10 hours to obtain an ionic liquid gel. The ionic liquid gel was then spread on the surface of the positive electrode and cold-pressed.

[0245] The cells are stacked in the order of "negative electrode - solid electrolyte - ionic liquid gel - positive electrode", then wound to obtain a bare cell. The bare cell is then welded with tabs and installed in an aluminum shell. After sealing, the cells undergo processes such as standing, hot pressing, formation, and capacity testing to obtain a solid-state battery.

[0246] Performance tests were conducted as follows, all under normal temperature conditions (20℃~25℃), without applying pressure during the tests. The battery capacities of all embodiments and comparative examples were designed to be 185mAh / g~190mAh / g.

[0247] 1) Ionic conductivity

[0248] The prepared positive electrode sheet was cut into a 10mm diameter circle and fixed inside an insulating sleeve with an inner diameter of 10mm by stainless steel pillars on both sides. The outer side was connected to an electrochemical workstation for electrochemical impedance spectroscopy (EIS) testing. The test voltage was 10mV, and the test frequency range was 10... 6 Hz~0.1Hz. Based on the comparison of the obtained impedance spectrum, when Z (the imaginary part of the impedance) is 0, the value of Z' (the real part of the impedance) can be regarded as the ionic impedance Ri of this positive electrode. The ionic conductivity σ is calculated from the impedance and the thickness and area of ​​the electrode: σ=d / RiS (d is the thickness of the positive electrode, and S is the measured area of ​​the positive electrode).

[0249] Note: The ionic conductivity of the positive electrode in Comparative Example 3 was measured when the surface of the positive electrode was coated with a gel electrolyte.

[0250] 2) First effect

[0251] Charge at a constant current of 0.1C to 4.3V, then switch to constant voltage charging until the current is less than 0.05C. Record the first charge capacity C1 at 0.1C. Then discharge at 0.1C to 2.5V and record the first discharge capacity C2 at 0.1C. First efficiency = C2 / C1 × 100%.

[0252] 3) Cyclic performance

[0253] The battery was charged at a constant current of 0.33C to 4.3V, then switched to constant voltage charging until the current was less than 0.05C. It was then discharged at 0.33C to 2.5V, and the initial discharge capacity C1 at 0.33C was recorded. This cycle was repeated 60 times, and the discharge capacity after 60 cycles was recorded. Since the design capacity of the batteries in each embodiment and the comparative example is the same, the discharge capacity after the same number of cycles (60 cycles) can reflect the quality of cycle performance.

[0254] Table 1

[0255] The test results are shown in Table 1. The results show that, compared to Comparative Examples 1 to 3, the positive electrode sheets of Examples 1 to 3 have higher ionic conductivity, and the batteries exhibit higher initial efficiency and better cycle performance. Meanwhile, Examples 4 and 5 also have performance comparable to Example 1.

[0256] This is mainly because in Examples 1 to 5, the ionic liquid gel electrolyte precursor solution is sprayed onto the surface of the positive electrode sheet. This precursor solution partially penetrates into the interior of the positive electrode active layer and partially remains on the surface. During high-temperature treatment, the precursor solution polymerizes to form the ionic liquid gel electrolyte. Thus, the resulting positive electrode sheet has ionic liquid gel electrolyte distributed both inside and on the surface of the positive electrode active layer. These ionic liquid gel electrolytes provide ion conduction channels both inside and on the surface of the positive electrode sheet, thereby promoting ion conduction and improving the ionic conductivity of the positive electrode sheet. Furthermore, the ionic liquid gel electrolyte on the surface of the positive electrode active layer improves the interfacial contact between the positive electrode sheet and the solid electrolyte membrane during charging and discharging, allowing ions to be effectively conducted between the positive electrode sheet and the solid electrolyte membrane, which is beneficial for maximizing battery capacity and thus improving the battery's initial efficiency and overall performance.

[0257] In contrast, the positive electrode in Comparative Example 1 does not contain an ionic liquid gel electrolyte. The gaps between the positive electrode active material particles within it hinder ion conduction, resulting in low ionic conductivity. Furthermore, the poor solid-solid contact between the positive electrode and the solid electrolyte negatively impacts the battery's initial efficiency and cycle performance.

[0258] Although Comparative Example 2 sprayed a solution c containing ionic liquid onto the surface of the positive electrode, since solution c does not contain inorganic nanoparticles, it can only polymerize on the surface of the positive electrode active layer to form an ionic liquid gel electrolyte. It is difficult to form a gel inside the positive electrode active layer, which makes it difficult to promote ion conduction inside the positive electrode active layer. This results in the positive electrode exhibiting low ionic conductivity, which also affects the battery's initial efficiency and discharge capacity after cycling.

[0259] In Comparative Example 3, the ionic liquid gel electrolyte is independent of the positive electrode and sandwiched between the positive electrode and the solid electrolyte. It is also difficult to promote ion conduction inside the positive electrode active layer, resulting in low ionic conductivity of the positive electrode and affecting the discharge capacity of the battery after the first cycle.

[0260] 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 positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive electrode layer disposed on at least one side of the positive current collector; Its features are, Along the direction away from the positive electrode current collector, the positive electrode layer includes a first film layer and a second film layer stacked sequentially. The first membrane layer includes a positive electrode active material and a first gel electrolyte, wherein the first gel electrolyte is distributed between the positive electrode active materials; The second membrane layer includes a second gel electrolyte.

2. The solid-state battery cell according to claim 1, characterized in that, At the interface between the first membrane layer and the second membrane layer, the first gel electrolyte and the second gel electrolyte are in contact with each other.

3. The solid-state battery cell according to claim 1 or 2, characterized in that, The first gel electrolyte and the second gel electrolyte each independently comprise an ionic liquid, a polymer, and inorganic nanoparticles.

4. The solid-state battery cell according to claim 3, characterized in that, The anions contained in the ionic liquid include one or more of bis(fluorosulfonyl)imide anion, bis(trifluoromethanesulfonyl)imide anion, and trifluoromethanesulfonic acid anion; and / or, The cations contained in the ionic liquid include one or more of the following: pyrrolidine cations, imidazole cations, piperidine cations, pyridine cations, and thiophene cations.

5. The solid-state battery cell according to claim 3 or 4, characterized in that, The polymers include one or more of the following: polyvinylidene fluoride-hexafluoropropylene copolymer, nitrile rubber, saturated ester polymers, polyacrylonitrile, polyoxyethylene, polyoxypropylene, polyvinyl chloride, polymethyl methacrylate, and polyvinylidene fluoride.

6. The solid-state battery cell according to any one of claims 3 to 5, characterized in that, The inorganic nanoparticles include one or more of nano-SiO2, nano-TiO2, nano-Al2O3, nano-MgO, nano-ZrO2, and nano-ZnO2.

7. The solid-state battery cell according to any one of claims 3 to 6, characterized in that, The first gel electrolyte and the second gel electrolyte each independently comprise an electrolyte salt.

8. The solid-state battery cell according to claim 7, characterized in that, The mass ratio of the ionic liquid to the polymer is 1:(0.2-2); and / or, The mass ratio of the ionic liquid to the inorganic nanoparticles is 1:(0.005–0.1); and / or, The mass ratio of the ionic liquid to the electrolyte salt is 1:(0.2-2).

9. The solid-state battery cell according to claim 7 or 8, characterized in that, The mass ratio of the ionic liquid to the polymer is 1:(0.4-1); and / or, The mass ratio of the ionic liquid to the inorganic nanoparticles is 1:(0.01–0.1); and / or, The mass ratio of the ionic liquid to the electrolyte salt is 1:(0.4~1).

10. The solid-state battery cell according to any one of claims 1 to 9, characterized in that, The total content of the first gel electrolyte and the second gel electrolyte in the positive electrode layer is 1 mg / cm³. 2 ~3mg / cm 2 ; and / or, The thickness of the second film layer is 0.5 μm to 3 μm.

11. The solid-state battery cell according to any one of claims 1 to 10, characterized in that, The total content of the first gel electrolyte and the second gel electrolyte in the positive electrode layer is 1.5 mg / cm³. 2 ~2.5mg / cm 2 ; and / or, The thickness of the second film layer is 1 μm to 2 μm.

12. A positive electrode sheet, comprising a positive current collector and a positive electrode layer disposed on at least one side of the positive current collector; Its features are, Along the direction away from the positive electrode current collector, the positive electrode layer includes a first film layer and a second film layer stacked sequentially. The first membrane layer includes a positive electrode active material and a first gel electrolyte, wherein the first gel electrolyte is distributed between the positive electrode active materials; The second membrane layer includes a second gel electrolyte.

13. A method for preparing a positive electrode sheet, characterized in that, include: A first film layer comprising a positive electrode active material is prepared on at least one side of the positive electrode current collector; A gel electrolyte precursor solution is distributed on the surface and inside the first membrane layer; The gel electrolyte precursor solution is subjected to gelation treatment, so that the gel electrolyte precursor solution forms a first gel electrolyte in the first membrane layer and a second gel electrolyte forms on the surface of the first membrane layer.

14. The method for preparing the positive electrode sheet according to claim 13, characterized in that, The gel electrolyte precursor solution includes ionic liquids, oligomers or polymer monomers, and inorganic nanoparticles.

15. The method for preparing the positive electrode sheet according to claim 14, characterized in that, The Dv50 of the inorganic nanoparticles is 1nm to 100nm.

16. The method for preparing the positive electrode sheet according to claim 14 or 15, characterized in that, The Dv50 of the inorganic nanoparticles is 1nm to 50nm.

17. The method for preparing the positive electrode sheet according to any one of claims 14 to 16, characterized in that, The gel electrolyte precursor solution also includes electrolyte salts.

18. The method for preparing the positive electrode sheet according to any one of claims 14 to 17, characterized in that, The preparation method of the gel electrolyte precursor solution includes: The solution a containing the ionic liquid is mixed with the solution b containing the oligomer or the polymer monomer; the resulting mixed solution is then mixed with the inorganic nanoparticles.

19. The method for preparing the positive electrode sheet according to any one of claims 13 to 18, characterized in that, A method for distributing the gel electrolyte precursor solution on the surface and inside the first membrane layer includes: coating the gel electrolyte precursor solution on the surface of the first membrane layer.

20. The method for preparing the positive electrode sheet according to claim 19, characterized in that, The coating amount of the gel electrolyte precursor solution is 5 mg / cm³. 2 ~15mg / cm 2 .

21. The method for preparing the positive electrode sheet according to claim 20, characterized in that, The coating amount of the gel electrolyte precursor solution is 8 mg / cm³. 2 ~12mg / cm 2 .

22. The method for preparing the positive electrode sheet according to any one of claims 13 to 21, characterized in that, The gelation treatment method includes one or more of the following: heat treatment, radiation treatment, and light treatment.

23. A battery device, characterized in that, It includes any one of the solid-state battery cells described in claims 1 to 11.

24. An energy storage device, characterized in that, It includes a solid-state battery cell according to any one of claims 1 to 11 or a battery device according to claims 23, wherein the solid-state battery cell or the battery device is used to store or provide electrical energy.

25. An electrical appliance, characterized in that, It includes a solid-state battery cell according to any one of claims 1 to 11 or a battery device according to claims 23, wherein the solid-state battery cell or the battery device is used to store or provide electrical energy.

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