Battery cell, composite electrolyte, battery apparatus and electric apparatus

Abstract

A battery cell, a composite electrolyte, a battery apparatus and an electric apparatus. The battery cell comprises: a positive electrode sheet, a composite electrolyte and a negative electrode sheet, wherein the composite electrolyte comprises a solid electrolyte sheet and a liquid electrolyte, the solid electrolyte sheet is arranged between the positive electrode sheet and the negative electrode sheet, the solid electrolyte sheet comprises a solid electrolyte and a plurality of voids, and the liquid electrolyte can permeate into the voids; and in the composite electrolyte, the mass percentage content of the solid electrolyte is A, the mass percentage content of the liquid electrolyte is B, and the mass percentages of the solid electrolyte and the liquid electrolyte satisfy: 5≤A / B≤950. In the composite electrolyte of the battery cell, the solid electrolyte and the liquid electrolyte are combined, and the liquid electrolyte can permeate into the voids in the solid electrolyte sheet, thereby improving the ionic conductivity and effectively mitigating the problem of poor contact at a contact interface between an electrolyte and an electrode.

Description

Battery cells, compound electrolytes, battery devices and electrical devices

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application 202411942047.X, filed on December 26, 2024, entitled “Battery cell, composite electrolyte, battery device and power consumption device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to a battery cell, a composite electrolyte, a battery device, and an electrical device. Background Technology

[0004] Compared to liquid batteries, solid-state batteries use solid electrolytes, which are less prone to combustion and explosion, thus offering higher reliability. Currently, the main obstacle to the commercialization of solid-state batteries lies in the poor solid-solid interface contact between the electrolyte and the electrodes, resulting in low ionic conductivity, high internal resistance, and negatively impacting their electrochemical performance. Summary of the Invention

[0005] This application provides a battery cell, a composite electrolyte, a battery device, and an electrical device, wherein the battery cell has good electrochemical performance.

[0006] In a first aspect, embodiments of this application provide a battery cell comprising: a positive electrode, a composite electrolyte, and a negative electrode. The composite electrolyte comprises a solid electrolyte sheet and a liquid electrolyte. The solid electrolyte sheet is disposed between the positive and negative electrode sheets and comprises a solid electrolyte and a plurality of pores, wherein the liquid electrolyte can permeate into the pores. In the composite electrolyte, the mass percentage of the solid electrolyte is A, the mass percentage of the liquid electrolyte is B, and the mass percentages of the solid electrolyte and the liquid electrolyte satisfy: 5 ≤ A / B ≤ 950.

[0007] In the composite electrolyte of the battery cell of this application, solid electrolyte and liquid electrolyte are combined. The liquid electrolyte can permeate into the voids in the solid electrolyte sheet, thereby improving the ionic conductivity and further reducing the internal resistance of the electrolyte itself. On the other hand, the liquid electrolyte can flow through the voids in the solid electrolyte to the contact interface between the solid electrolyte sheet and the electrode. The liquid electrolyte can effectively improve the problem of poor contact between the electrolyte and the electrode.

[0008] Therefore, the battery cell of this application has improved mechanical performance while having higher capacity retention and lower short-circuit rate.

[0009] In some embodiments, the mass percentage of solid electrolyte and liquid electrolyte in the composite electrolyte of a battery cell satisfies: 20 ≤ A / B ≤ 30.

[0010] In some embodiments, the mass percentage A of the solid electrolyte in the composite electrolyte of the battery cell satisfies: 85% ≤ A ≤ 98%; and the mass percentage B of the liquid electrolyte satisfies: 0.1% ≤ B ≤ 15%.

[0011] Therefore, when the mass percentage A of the solid electrolyte satisfies 85% ≤ A ≤ 98% and the mass percentage B of the liquid electrolyte satisfies 0.1% ≤ B ≤ 15%, the electrochemical performance of the composite electrolyte of this application is improved, and the solid-solid interface performance between the composite electrolyte and the electrode is improved.

[0012] In some embodiments, the mass percentage A of the solid electrolyte in the composite electrolyte of the battery cell satisfies: 90% ≤ A ≤ 94%; and the mass percentage B of the liquid electrolyte satisfies: 1% ≤ B ≤ 5%.

[0013] In some embodiments, the liquid electrolyte includes liquid metals and / or ionic liquids.

[0014] In some embodiments, the liquid metal includes one or more gallium-based liquid metals, and the ionic liquid includes one or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and lithium-tetraethylene glycol dimethyl ether-bis(trifluoromethanesulfonyl)imide salt prepared by mixing lithium bis(trifluoromethylflamyl)imide and tetraethylene glycol dimethyl ether in a molar ratio of 1:1.

[0015] In some embodiments, the composite electrolyte of the battery cell may further include a binder, wherein the mass percentage of the binder in the composite electrolyte is C, and the mass percentage A / C of the solid electrolyte and the binder can satisfy: 20≤A / C≤200.

[0016] Therefore, with the mass percentage of solid electrolyte and binder within 20 ≤ A / C ≤ 200, the binder can achieve good adhesion with other components in the composite electrolyte, enabling the battery cell to have both good fast-charging performance and high energy density.

[0017] In some embodiments, the adhesive includes one or more of polyvinyl alcohol, polyethylene oxide, sodium carboxymethyl cellulose, butadiene rubber, silicone rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, styrene-ethylene-butene-benzene copolymer, polyvinylidene fluoride-hexafluoropropylene, nitrile rubber, and hydrogenated nitrile rubber.

[0018] In some embodiments, the composite electrolyte of the battery cell may further include a dispersant, wherein the mass percentage of the dispersant in the composite electrolyte is D, and the mass percentage A / D of the solid electrolyte and the dispersant can satisfy: 100≤A / D≤950.

[0019] Therefore, when the mass percentage of solid electrolyte and dispersant is within 100 ≤ A / D ≤ 950, the dispersant can effectively solve the problems of solid electrolyte agglomeration and uneven dispersion during the preparation of composite electrolytes, and improve the flowability of solid electrolytes during the preparation process.

[0020] In some embodiments, the dispersant includes one or more of polyvinyl alcohol, polyacrylamide, polyether-modified siloxane, fluorocarbon-modified acrylic resin, and polyvinylpyrrolidone.

[0021] In some embodiments, the solid electrolyte includes one or more of oxide solid electrolytes, halide solid electrolytes, sulfide solid electrolytes, and polymer solid electrolytes.

[0022] In some embodiments, the composite electrolyte of the battery cell may further include a porous polymer support, with a solid electrolyte sheet disposed on at least one side surface of the porous polymer support or in the pores of the porous polymer support, and the thickness ratio of the composite electrolyte to the porous polymer support is 12:1 to 1:1.

[0023] Therefore, in the above embodiments, the porous polymer support can provide good mechanical strength for the composite electrolyte, reducing its rupture or deformation under pressure, vibration, or other external forces. The porous polymer support can alleviate the mechanical stress on the solid electrolyte caused by the volume expansion and contraction of the electrode material, further improving the plasticity and flexibility of the composite electrolyte. Simultaneously, it can help stabilize ion transport channels and voids, allowing ions to migrate smoothly within the solid electrolyte. Furthermore, when the thickness ratio of the composite electrolyte to the porous polymer support is 12:1 to 1:1, on the one hand, the solid electrolyte can provide sufficient ion storage and transport capacity; on the other hand, the porous polymer support can guide the rapid transport of ions between the electrolyte and the electrode.

[0024] In some embodiments, the porous polymer support includes one or more of propylene fibers, polyester fibers, nylon fibers, polyethylene fibers, and bio-based materials.

[0025] In some embodiments, the composite electrolyte satisfies at least one of the following conditions: the thickness of the composite electrolyte is 5 μm to 60 μm, at which thickness the composite electrolyte can improve mechanical stability and ion transport rate while increasing ion storage capacity; the areal density of the composite electrolyte is 0.5 mg / cm³. 2 ~18mg / cm 2At this areal density, the composite electrolyte further improves the battery energy density and charge / discharge performance while enhancing heat dissipation. The porosity of the composite electrolyte is 1% to 15%, and the pore size distribution is 0.1 μm to 100 μm. With this porosity and pore size distribution, the composite electrolyte can fully fill the liquid electrolyte.

[0026] In some embodiments, the composite electrolyte of the battery cell satisfies at least one of the following conditions: the ionic conductivity of the composite electrolyte is 0.1 mS / cm to 10 mS / cm, at which the battery cell prepared using the composite electrolyte has better low-temperature performance and better charge-discharge performance; the tensile strength of the composite electrolyte is 0.2 MPa to 30 MPa; and the AC internal resistance of the composite electrolyte is 0.76 Ω to 6.4 Ω.

[0027] In some embodiments, the battery cell meets at least one of the following conditions: at a current of 0.1C, the first-cycle discharge specific capacity of the battery cell is 160mAh / g to 400mAh / g; at a current of 0.1C, the capacity retention rate of the battery cell after 100 cycles is 80% to 100%.

[0028] Secondly, this application provides a composite electrolyte for a battery cell. The composite electrolyte includes a solid electrolyte sheet and a liquid electrolyte. The solid electrolyte sheet is disposed between a positive electrode and a negative electrode. The solid electrolyte sheet includes a solid electrolyte and a plurality of voids extending along the thickness direction of the solid electrolyte sheet, through which the liquid electrolyte can pass. The mass percentage of solid electrolyte to liquid electrolyte in the composite electrolyte is 9 ≤ A / B ≤ 950. The composite electrolyte has high ionic conductivity, which can improve the problem of poor solid-solid interface contact between the electrode and the electrolyte in the battery cell.

[0029] Thirdly, this application provides a battery device, including a battery cell as described in the first aspect or a battery cell formed by preparing a composite electrolyte as described in the second aspect.

[0030] The fourth aspect is an electrical device, including the battery device of the third aspect. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described 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 the drawings without creative effort.

[0032] Figure 1 is a schematic diagram of one embodiment of the battery cell of this application.

[0033] Figure 2 is a schematic diagram of one embodiment of an electrical device that uses the battery of this application as a power source.

[0034] Figure 3 is a diagram of the electrolyte conduction mechanism in existing solid-state batteries.

[0035] Figure 4 is a schematic diagram of the conductivity mechanism of the composite electrolyte in one embodiment of the battery cell of this application.

[0036] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0037] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, composite electrolyte, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions 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.

[0038] 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 expected that ranges of 60-110 and 80-120 are also included. 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 "ab" 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.

[0039] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0040] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0041] 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.

[0042] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0043] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0044] The battery cells mentioned in the embodiments of this application are capable of charging and discharging independently. The battery cells may be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited in this respect. Figure 1 shows an example of a cuboid battery cell.

[0045] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0046] The battery cell provided in the embodiments of this application includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator disposed between the negative electrode and the positive electrode. During the charging and discharging process of the battery cell, active ions (e.g., lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, disposed between the positive and negative electrodes, serves to prevent short circuits between the positive and negative electrodes while allowing active ions to pass through. The electrode assembly can be a wound structure or a stacked structure; the embodiments of this application are not limited in this regard.

[0047] The battery cell also includes an outer packaging, which encapsulates the electrode components and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. It can also be a flexible package, such as a pouch. The material of the flexible package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0048] The battery cells provided in the embodiments of this application can be lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium-sulfur battery cells, magnesium-ion battery cells, nickel-metal hydride battery cells, nickel-cadmium battery cells, lead-acid battery cells, etc., and the embodiments of this application are not limited to these.

[0049] The method for preparing the battery cell of this application is well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained.

[0050] 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 battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0051] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0052] 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.

[0053] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0054] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0055] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., 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. Battery cells and battery devices are used to store or provide electrical energy.

[0060] Figure 2 is a schematic diagram of an example electrical device. The electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. Sulfide solid electrolytes are considered to be very promising solid electrolyte materials because they have ionic conductivity comparable to liquid electrolytes and relatively good processing performance. Currently, sulfide electrolytes are mainly applied to all-solid-state batteries through two film formation methods: (1) Dry film formation: The solid electrolyte membrane is prepared by dry rolling by combining sulfide with binder. Although this method can reduce the thickness of the solid electrolyte layer to a certain extent, the degree of thinning is limited. Because when the amount of binder added is small, the mechanical properties of the thinned solid electrolyte membrane will deteriorate, which will cause great problems for battery processing and will not promote its application in actual industrial production. When the amount of PTFE binder added is too large, the mechanical properties of the thinned solid electrolyte membrane are relatively good, but its conductivity drops significantly, which in turn deteriorates the electrical performance of the battery. (2) Wet film formation: The sulfide, binder and organic solvent are mixed in a certain proportion to form a slurry and coated on the surface of the electrode sheet to prepare the electrode-supported sulfide electrolyte membrane. This method can prepare a thinner electrolyte coating layer, but it still has problems such as poor flexibility, stress sensitivity, and easy cracking when subjected to external force or volume change stress during battery charging and discharging, which can lead to lithium dendrite growth, short circuits, and battery cycle failure.

[0061] Besides the two film-forming methods mentioned above, a method using a three-dimensional porous polymer as a flexible support framework and further filling it with sulfide solid electrolyte can produce thinner electrolyte films with good flexibility, effectively reducing battery short-circuit rate and improving battery cycle performance. However, inorganic electrolyte slurries are difficult to fully fill the porous polymer substrate, and the contact resistance between the polymer matrix and the filled electrolyte particles is relatively large. In addition, the problem of poor solid-solid contact between the solid electrolyte and the electrode remains unresolved.

[0062] As shown in Figure 3, due to its own morphology and other issues, solid electrolytes may have problems such as the inability of adjacent solid electrolyte materials to make contact in some areas, resulting in the disconnection of conductive paths and leading to high internal resistance of the solid electrolyte sheet.

[0063] Based on this, the present application provides a battery cell in which the composite electrolyte has significantly improved ionic conductivity, significantly reduced internal resistance, and significantly improved solid-solid interface contact between the composite electrolyte and the electrode compared to a solid electrolyte.

[0064] The battery cell of this application includes: a positive electrode, a composite electrolyte, and a negative electrode.

[0065] The composite electrolyte includes a solid electrolyte sheet and a liquid electrolyte. The solid electrolyte sheet is disposed between the positive electrode and the negative electrode. The solid electrolyte sheet includes a solid electrolyte and multiple pores, and the liquid electrolyte can permeate into the pores.

[0066] In the composite electrolyte, the mass percentage of solid electrolyte is A, the mass percentage of liquid electrolyte is B, and the mass percentages of solid electrolyte and liquid electrolyte satisfy: 5≤A / B≤47.5.

[0067] As shown in Figure 4, the liquid electrolyte can pass through the gaps in the solid electrolyte sheet, thereby improving the ionic conductivity and further reducing the internal resistance of the electrolyte itself. On the other hand, the liquid electrolyte can flow through the gaps in the solid electrolyte to the contact interface between the solid electrolyte sheet and the electrode, and the liquid electrolyte can effectively improve the problem of poor contact between the electrolyte and the electrode.

[0068] Therefore, the battery cells provided in this application, provided that the mass percentage of solid electrolyte and liquid electrolyte in the battery cells meets the condition of 9≤A / B≤950, can improve the mechanical performance of the battery cells while having a higher capacity retention rate and a lower short-circuit rate.

[0069] In this application, the methods for testing the content of both solid and liquid electrolytes are common knowledge and can be performed using instruments and methods known in the art, such as high-performance liquid chromatography (HPLC). The solid sample is pretreated by dissolving and extracting, and then injected into the HPLC instrument. The liquid electrolyte is separated from other substances based on the difference in their partition coefficients between the stationary and mobile phases, and the content of each component is then detected by a detector. Appropriate chromatographic columns and detectors, such as reversed-phase columns and ultraviolet detectors, are selected based on the structure and properties of the liquid electrolyte to achieve quantitative analysis of the liquid electrolyte.

[0070] The mass percentage A / B of solid electrolyte and liquid electrolyte in the battery cell provided in this application embodiment satisfies 5 ≤ ​​A / B ≤ 950. For example, A / B can be 5, 10, 20, 30, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or any range of the above values.

[0071] Optionally, 20≤A / B≤30, 21≤A / B≤30, 22≤A / B≤30, 23≤A / B≤30, 24≤A / B≤30, 25≤A / B≤30, 26≤A / B≤30, 27≤A / B≤30, 28≤A / B≤30, 29≤A / B≤30.

[0072] In some embodiments, the mass percentage A of the solid electrolyte in the composite electrolyte of the battery cell provided in this application satisfies: 85% ≤ A ≤ 98%. For example, A can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or any range of the above values. The mass percentage B of the liquid electrolyte in the composite electrolyte satisfies: 0.1% ≤ B ≤ 15%. For example, B can be 0.1%, 0.2%, 0.3%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 15%, or any range of the above values.

[0073] Alternatively, 90% ≤ A ≤ 95%, 90% ≤ A ≤ 94%, 90% ≤ A ≤ 93%, 90% ≤ A ≤ 92%, and 90% ≤ A ≤ 91%.

[0074] Optionally, 1% ≤ B ≤ 5%, 1% ≤ B ≤ 4%, 1% ≤ B ≤ 3%, 1% ≤ B ≤ 2%, and 1% ≤ B ≤ 1.5%.

[0075] In the above embodiments, when the mass percentage A of the solid electrolyte satisfies: 85% ≤ A ≤ 98%, and the mass percentage B of the liquid electrolyte satisfies: 0.1% ≤ B ≤ 10%, the electrochemical performance of the composite electrolyte of this application is improved, and the solid-solid interface performance between the composite electrolyte and the electrode is improved.

[0076] In some embodiments, the liquid electrolyte in the battery cell provided in this embodiment includes liquid metal and / or ionic liquid.

[0077] Optionally, the liquid metal includes one or more gallium-based liquid metals, which may be gallium indium tin alloy and / or gallium indium zinc alloy, etc.

[0078] Optionally, the ionic liquid includes one or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIMTFSI), 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIMTFSI), and lithium-tetraethylene glycol dimethyl ether-bis(trifluoromethanesulfonyl)imide (Li[G4]TFSI) prepared by mixing lithium bis(trifluoromethylxanthyl)imide (LiTFSI) and tetraethylene glycol dimethyl ether (G4) in equimolar amounts.

[0079] In some embodiments, the composite electrolyte of the battery cell provided in this embodiment may further include a binder, wherein the mass percentage of the binder in the composite electrolyte is C, and the mass percentage A / C of the solid electrolyte and the binder may satisfy: 40≤A / C≤95. For example, A / C may be 40, 42, 45, 48, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or any range of the above values.

[0080] In the above embodiments, the mass percentages of the solid electrolyte and the binder are within the above range. The binder can achieve good adhesion with other components in the composite electrolyte, enabling the battery cell to have both good fast charging performance and high energy density.

[0081] Optionally, 80≤A / C≤95, 82≤A / C≤95, 84≤A / C≤95, 86≤A / C≤95, 88≤A / C≤95, 90≤A / C≤95, 92≤A / C≤95, and 94≤A / C≤95.

[0082] Optionally, the binder includes one or more of hydrogenated nitrile butadiene rubber (HNBR), polyvinyl alcohol (PVA), polyethylene oxide (PEO), sodium carboxymethyl cellulose (CMC-Na), butadiene rubber (BR), silicone rubber, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and styrene-ethylene-butene-benzene copolymer (SEBS).

[0083] In this application, the methods for testing the binder content are all common knowledge and can be performed using instruments and methods known in the art. For example, thermogravimetric analysis can be used to determine the binder content by measuring the mass change of the sample during heating. During heating, the binder gradually decomposes or volatilizes, resulting in a decrease in sample mass. Based on the mass-temperature curve, the decomposition temperature range of the binder and the mass loss within that temperature range can be determined, thereby calculating the binder content.

[0084] In some embodiments, the composite electrolyte of the battery cell provided in this embodiment may further include a dispersant. The mass percentage of the dispersant in the composite electrolyte is D. The mass percentage A / D of the solid electrolyte and the dispersant may satisfy: 100≤A / D≤950. For example, it may be 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or any range of the above values.

[0085] In the above embodiments, the mass percentages of solid electrolyte and dispersant are within the above range. The dispersant can effectively solve the problems of solid electrolyte agglomeration and uneven dispersion during the preparation of composite electrolytes, and improve the flowability of solid electrolytes during the preparation process.

[0086] In this application, the methods for testing the content of dispersant are all common knowledge and can be tested using instruments and methods known in the art. For example, thermogravimetric analysis can be used to accurately measure the mass change curve of the sample during the programmed temperature rise process using a thermogravimetric analyzer, and the content of dispersant can be determined based on the mass loss at different stages of the curve.

[0087] Optionally, 100≤A / D≤500, 150≤A / D≤500, 200≤A / D≤500, 250≤A / D≤500, 300≤A / D≤500, 350≤A / D≤500, 400≤A / D≤500, and 450≤A / D≤500.

[0088] Optionally, the dispersant includes one or more of polyvinyl alcohol, polyacrylamide, polyether-modified siloxane, fluorocarbon-modified acrylic resin, and polyvinylpyrrolidone.

[0089] In some embodiments, the solid electrolyte includes one or more of oxide solid electrolytes, halide solid electrolytes, sulfide solid electrolytes, and polymer solid electrolytes.

[0090] Optionally, the oxide solid electrolyte can be one or more of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium titanium oxide (LLZTO), lithium phosphorus oxynitrogen (LiPON), lithium tantalate (LTO), lithium titanium aluminum phosphate (LATP), and lithium lanthanum germanate (LAGP).

[0091] Optionally, the halide solid electrolyte can be Li3InCl6, Li2ZrCl6, or Li 5 / 3 Cr 1 / 3 Zr 1 / 3 Cl4, Li3YCl6, Li3ScCl6, Li 0.388 Ta 0.438 La 0.475 Cl3 and Li3MCl 6-x Br x One or more of them.

[0092] Alternatively, the sulfide solid electrolyte can be lithium germanium phosphorus sulfide (Li... 10 GeP2S 12 LGPS), silver-sulfur germanium ore type (Li6PS5X, X = Cl, Br, I), lithium-phosphorus sulfur (Li7P3S) 11 One or more of the following: lithium phosphide (LPS), lithium oxysulfide, lithium yttrium sulfide (Li6PS5Y), and lithium lanthanum sulfide (Li6PS5La).

[0093] Optionally, the polymer solid electrolyte can be one or more of the following: polyethylene oxide (PEO) based solid electrolyte, polysiloxane (PS) based solid electrolyte, polyacrylonitrile (PAN) based solid electrolyte, polymethyl methacrylate (PMMA) based solid electrolyte, polyvinylidene fluoride (PVDF) based solid electrolyte, and metal-organic framework (MOF) based solid polymer electrolyte.

[0094] In some embodiments, the composite electrolyte of the battery cell provided in this embodiment may further include a porous polymer support, with a solid electrolyte sheet disposed on at least one side surface of the porous polymer support or in the pores of the porous polymer support. The thickness ratio of the composite electrolyte to the porous polymer support is 12:1 to 1:1, for example, it can be 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, or any range of the above values.

[0095] In the above embodiments, the porous polymer support can provide good mechanical strength for the composite electrolyte, reducing the risk of cracking or deformation when subjected to pressure, vibration or other external forces. In other words, the porous polymer support can reduce the mechanical stress caused by the volume expansion and contraction of the electrode material on the solid electrolyte, further improving the plasticity and flexibility of the composite electrolyte. At the same time, it can help stabilize ion transport channels and gaps, enabling ions to migrate smoothly in the solid electrolyte.

[0096] Furthermore, when the thickness ratio of the composite electrolyte to the porous polymer support is 12:1 to 1:1, the solid electrolyte can provide sufficient ion storage and transport capacity on the one hand, and the porous polymer support can guide ions to transport rapidly between the electrolyte and the electrode on the other hand.

[0097] In this application, the testing methods for the thickness of the porous polymer support and the composite electrolyte are common knowledge and can be tested using instruments and methods known in the art, such as observing the cross-section of the solid electrolyte with an optical microscope and directly measuring its thickness using the microscope's imaging system and measuring tools.

[0098] Optionally, the porous polymer support includes one or more of acrylic fiber (PP), polyester fiber (PET), nylon fiber (PA), polyethylene fiber (PE), and bio-based materials.

[0099] In some embodiments, the composite electrolyte of the battery cell provided in this embodiment satisfies at least one of the following conditions: the thickness of the composite electrolyte is 5μm to 60μm, for example, it can be 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, or any range of the above values. At this thickness, the composite electrolyte can improve mechanical stability and ion transport rate while increasing ion storage capacity; the areal density of the composite electrolyte is 0.5mg / cm³. 2 ~18mg / cm 2 For example, it could be 0.5 mg / cm³. 2 1mg / cm 2 2mg / cm 2 3mg / cm 2 4mg / cm 2 5mg / cm 2 6mg / cm 2 7mg / cm 2 8mg / cm 2 9mg / cm 2 10mg / cm 2 12mg / cm 2 15mg / cm 2 18mg / cm2 The composite electrolyte has a porosity of 1% to 15%, for example, it can be 1%, 2%, 3%, 5%, 8%, 10%, 12%, 15%, or any of the above values. The composite electrolyte has a pore size distribution of 0.1μm to 100μm, for example, it can be 0.1μm, 1μm, 2μm, 5μm, 8μm, 10μm, 20μm, 30μm, 50μm, 80μm, 100μm, or any of the above values. With this porosity and pore size distribution, the composite electrolyte can fully fill the liquid electrolyte.

[0100] In this application, the methods for testing the areal density of the composite electrolyte are common knowledge and can be performed using instruments and methods known in the art. For example, optical measurement methods can be used, where optical instruments are used to image the solid electrolyte sample, and image analysis software is used to measure the optical parameters related to the sample's area and mass, thereby calculating the areal density. Similarly, the methods for testing the porosity and pore size distribution of the composite electrolyte are common knowledge and can be performed using instruments and methods known in the art. For example, gas adsorption methods can be used, based on the physical adsorption phenomenon of gas on a solid surface, by measuring the relationship between the amount of gas adsorbed on the composite electrolyte and the pressure to obtain porosity and pore size distribution information.

[0101] In some embodiments, the composite electrolyte of the battery cell provided in this embodiment satisfies at least one of the following conditions: the ionic conductivity of the composite electrolyte is 0.1 mS / cm to 10 mS / cm, for example, it can be 0.1 mS / cm, 0.2 mS / cm, 0.5 mS / cm, 1 mS / cm, 2 mS / cm, 3 mS / cm, 4 mS / cm, 5 mS / cm, 6 mS / cm, 7 mS / cm, 8 mS / cm, 9 mS / cm, 10 mS / cm, or any range of the above values. At this ionic conductivity, the battery cell prepared using this composite electrolyte has better low-temperature performance and better charge-discharge performance; the tensile strength of the composite electrolyte is... The internal resistance of the composite electrolyte is 0.2 MPa to 30 MPa, for example, it can be 0.2 MPa, 0.5 MPa, 1 MPa, 2 MPa, 5 MPa, 8 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, or any combination of the above values; the internal resistance of the composite electrolyte is 0.76 Ω to 6.4 Ω, for example, it can be 0.76 Ω, 0.765 Ω, 0.77 Ω, 0.775 Ω, 0.78 Ω, 0.785 Ω, 0.79 Ω, 0.795 Ω, 0.8 Ω, 0.81 Ω, 0.82 Ω, 0.85 Ω, 0.9 Ω, 1 Ω, 2 Ω, 3 Ω, 4 Ω, 5 Ω, 6 Ω, 6.4 Ω, or any combination of the above values.

[0102] In some embodiments, the battery cell satisfies at least one of the following conditions: the current is 0.1C, and the first-cycle discharge specific capacity of the battery cell is 160mAh / g to 400mAh / g, for example, it can be 160mAh / g, 180mAh / g, 200mAh / g, 220mAh / g, 240mAh / g, 260mAh / g, 280mAh / g, 300mAh / g, 320mAh / g, 340mAh / g, 360mAh / g, 380mAh / g, 400mAh / g, or any range of the above values; the current is 0.1C, and the capacity retention rate of the battery cell after 100 cycles is 80% to 100%, for example, it can be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, 100%, or any range of the above values.

[0103] [Positive electrode tablets]

[0104] The structure and composition of the positive electrode can be selected according to the type of battery cell, and the embodiments of this application are not limited in this regard.

[0105] In some embodiments, the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0106] When the battery cell is a lithium battery, the positive electrode active material includes materials capable of extracting and inserting lithium. As examples, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, lithium manganese iron phosphate and carbon composites, and their respective modified compounds.

[0107] In some embodiments, to further improve the energy density of a single battery cell, the positive electrode active material may include materials of the general formula Li. a Ni b Co c M d O e D f One or more of lithium transition metal oxides and their modified compounds. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M may include, but is not limited to, one or more of Ge, Mo, Sn, Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and D may include, but is not limited to, one or more of N, F, S and Cl.

[0108] As an example, the positive electrode active material may include, but is not limited to, LiCoO2, LiNiO2, LiMnO2, and LiNi 1 / 2 Mn 1 / 2 O2, LiMn2O4, Li 4 / 3 Ti 5 / 3 O4, LiNi 1 / 2 Mn 1 / 2 O2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 O2, LiFePO4, LiMnPO4, Li 1.13 Ti 0.57 Fe 0.3 One or more of S2.

[0109] In some embodiments, the positive electrode active material may include a solid electrolyte material, which may include one or more of sulfide solid electrolyte materials, halide solid electrolyte materials, and oxide solid electrolyte materials. Optionally, the solid electrolyte material may include a sulfide solid electrolyte material.

[0110] In some embodiments, sulfide solid electrolyte materials may include one or more of the following: silver sulfide-germanium ore type, LGPS type, and lithium sulfide-phosphorus pentasulfide complex type sulfide solid electrolyte materials.

[0111] Optionally, in some embodiments, the sulfide solid electrolyte material of the silver-germanium sulfide type may include Li 6±s P 1-j A j S 5±s-t B t D 1±s The materials are 0≤j<1, 0≤t<1, 0≤s<1, A includes one or more elements from Ge, Si, Sn and Sb, B includes one or more elements from O, Se and Te, and D includes one or more elements from Cl, Br, I and F.

[0112] Optionally, in some embodiments, the LGPS-type sulfide solid electrolyte material may include Li 10±δ5 Ge 1-g G g P 2-q Q q S 12-w W w The material has the following properties: 0≤δ5<1, 0≤g≤1, 0≤q≤2, 0≤w<1, G includes one or two elements from Si and Sn, Q includes Sb, and W includes one or more elements from O, Se, Te, Cl, Br, I, and F.

[0113] Optionally, in some embodiments, the lithium sulfide - phosphorus pentasulfide composite - type sulfide solid electrolyte material may include a material with the chemical formula (100 - u - v)Li2S·uP2S5·vM m N n , where 0 < u < 100, 0 ≤ v < 100, 0 ≤ u + v < 100, 0 ≤ m < 4, 0 ≤ n < 6, M includes one or more elements selected from Li, B, Ge, Si, Sn, and Sb, and N includes one or more elements selected from S, Se, Te, O, Cl, Br, I, and F.

[0114] As an example, the sulfide solid electrolyte material may include one or more of Li6PS5Cl, Li6PS5Br, Li 10 GeP2S 12 , Li3PS4, Li7P3S 11 .

[0115] When the battery cell is a sodium battery, the positive electrode active material includes a material capable of deintercalating and intercalating sodium. As an example, the positive electrode active material may include, but is not limited to, one or more of layered transition metal oxides (including, but not limited to, P2 - type, O3 - type, etc.), polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), and Prussian - type materials.

[0116] In some embodiments, as an example, the positive electrode active material may include, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, Na 0.67 MO2 (M includes at least two of Fe, Co, Cr, Mn, Ni, V, Ti, Mo), NaMO2 (M includes at least two of Fe, Co, Ni, V, Ti, Mo), NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and their respective modified compounds.

[0117] The modified compounds of the above positive electrode active materials may be doping modification and / or surface coating modification of the positive electrode active material.

[0118] In some embodiments, the positive electrode film layer may also optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0119] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. As an example, the positive electrode binder may include, but is not limited to, one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resins, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0120] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0121] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing positive electrode active materials, optional positive electrode conductive agents, optional positive electrode binders, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to it.

[0122] [Negative electrode plate]

[0123] Each battery cell includes a negative electrode. The structure and composition of the negative electrode can be selected according to the type of battery cell, and the embodiments of this application are not limited in this regard.

[0124] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0125] The negative electrode active material may be any material known in the art. As an example, the negative electrode active material may include, but is not limited to, one or more of carbon-based materials, silicon-based materials, tin-based materials, and lithium titanate. Carbon-based materials may include, but are not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, pyrolytic carbon, coke, glassy carbon, sintered organic polymers, and mesophase carbon microspheres. Silicon-based materials may include, but are not limited to, one or more of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include, but are not limited to, one or more of elemental tin, tin oxides, and tin alloys.

[0126] In some embodiments, the negative electrode film layer may optionally include a negative electrode conductive agent. As an example, the negative electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0127] In some embodiments, the negative electrode film layer may optionally include a negative electrode binder. As an example, the negative electrode binder may include, but is not limited to, one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0128] In some embodiments, the negative electrode film layer may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0129] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0130] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet may also include a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector; in some embodiments, the negative electrode sheet may also include a protective layer covering the surface of the negative electrode film layer.

[0131] In some embodiments, the negative electrode sheet may include a negative current collector and a metal layer disposed on at least one surface of the negative current collector. The metal material in the metal layer may include, but is not limited to, one or more of elemental lithium, lithium alloy, elemental sodium, and sodium alloy.

[0132] Lithium alloys can be alloys formed from metallic lithium with other metallic or non-metallic elements. For example, other metallic elements in lithium alloys may include, but are not limited to, one or more elements selected from tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, while non-metallic elements in lithium alloys may include one or more elements selected from boron, carbon, and silicon.

[0133] Sodium alloys can be alloys formed by metallic sodium with other metallic or non-metallic elements. For example, other metallic elements in sodium alloys may include, but are not limited to, one or more of tin, zinc, aluminum, magnesium, silver, gold, gallium, indium, and platinum, while non-metallic elements in sodium alloys may include one or more of boron, carbon, and silicon.

[0134] In some embodiments, the negative electrode may be a lithium foil, a lithium alloy foil, a sodium foil, or a sodium alloy foil.

[0135] In some embodiments, the negative electrode sheet may include a negative electrode current collector to assemble a negative electrode-free battery cell.

[0136] In some embodiments, the negative electrode current collector may include, but is not limited to, one or more of the following: metal foil, metal foam current collector, metal mesh current collector, carbon felt current collector, carbon cloth current collector, carbon paper current collector, and composite current collector.

[0137] Examples of metal foil materials include copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, and aluminum alloy foil. Examples of metal foam current collectors include copper foam, nickel foam, and aluminum foam. Examples of metal mesh current collectors include copper mesh, nickel mesh, and aluminum mesh.

[0138] The composite current collector may include a polymeric material substrate and a metallic material layer formed on at least one surface of the polymeric material substrate. As examples, the metallic material may include, but is not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, aluminum, aluminum alloys, silver, and silver alloys. As examples, the polymeric material substrate may include, but is not limited to, one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE). [Preparation Method]

[0139] The methods for preparing battery cells are well known. For example, the assembly methods of battery cells include, but are not limited to, button cells, molded cells, prismatic cells, and pouch cells.

[0140] This application also provides a composite electrolyte for a battery cell, comprising a solid electrolyte sheet and a liquid electrolyte. The solid electrolyte sheet is disposed between a positive electrode and a negative electrode. The solid electrolyte sheet includes a solid electrolyte and a plurality of voids extending along the thickness direction of the solid electrolyte sheet. The liquid electrolyte can pass through the voids. The mass ratio of the solid electrolyte to the liquid electrolyte in the composite electrolyte is 9 ≤ A / B ≤ 950. For example, A / B can be 9, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or any range of the above values.

[0141] This application also provides a method for preparing a composite electrolyte for a battery cell, comprising: providing a slurry comprising a solid electrolyte and an ionic liquid, wherein the mass percentage of the solid electrolyte and the liquid electrolyte in the composite electrolyte in the slurry is 9 ≤ A / B ≤ 950, the solid content in the slurry is 30%-65%, and the slurry is prepared into a composite electrolyte by processes such as dip coating, dot coating, scraping coating, and spraying.

[0142] Example

[0143] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0144] Example 1

[0145] Preparation of composite electrolytes:

[0146] Weigh out the sulfide solid electrolyte, polymer binder, porous polymer support and ionic liquid.

[0147] A 50% solid electrolyte slurry was prepared by mixing and dispersing 90 parts of sulfide solid electrolyte, 1 part of polymer binder, and 3 parts of ionic liquid in an organic solvent. A 15mm thick porous polymer support was then completely immersed in the electrolyte slurry, passed through a 60μm slit, and dried to obtain a 30μm composite electrolyte. Specific parameters of each component are detailed in Table 1. The composite electrolyte has a thickness of 30μm and a surface density of 3.0 mg / cm³. 2 The porosity of the composite electrolyte is 2%, and the pore size distribution of the composite electrolyte is 0.2–1 μm.

[0148] Examples 2 to 7

[0149] The preparation method of the composite electrolyte is similar to that in Example 1, except that the mass ratio of the sulfide solid electrolyte and the liquid electrolyte used is different, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the composite electrolyte are detailed in Table 2.

[0150] Examples 8 to 11

[0151] The preparation method of the composite electrolyte is similar to that in Example 1, except that a different type of solid electrolyte is used, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the composite electrolyte are detailed in Table 2.

[0152] Examples 12 to 14

[0153] The preparation method of the composite electrolyte is similar to that in Example 1, except that the type of liquid electrolyte used is different, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the composite electrolyte are detailed in Table 2.

[0154] Examples 15 to 17

[0155] The preparation method of the composite electrolyte is similar to that of Example 1, except that the type and thickness of the porous polymer support used are different from those in Example 1, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the composite electrolyte are detailed in Table 2.

[0156] Examples 18 to 22

[0157] The preparation method of the composite electrolyte is similar to that of Example 1, except that the type or content of the polymer binder used is different from that in Example 1, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the composite electrolyte are detailed in Table 2.

[0158] Examples 23 to 24

[0159] The preparation method of the composite electrolyte is similar to that in Example 1, except that a dispersant is added to the slurry, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the composite electrolyte are detailed in Table 2.

[0160] Examples 25 to 26

[0161] The preparation method of the composite electrolyte is similar to that in Example 1, except for the thickness of the solid electrolyte sheet, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the composite electrolyte are detailed in Table 2.

[0162] Example 27

[0163] Weigh out the sulfide solid electrolyte, polymer binder, and ionic liquid.

[0164] A 50% solid electrolyte slurry was prepared by mixing and dispersing 96 parts of sulfide solid electrolyte, 1 part of polymer binder, and 3 parts of ionic liquid in an organic solvent. The electrolyte slurry was then coated onto the surface of an electrode sheet to prepare an electrode-supported composite electrolyte. The thickness, areal density, porosity, and pore size distribution of the composite electrolyte are detailed in Table 2.

[0165] Comparative Example 1

[0166] The preparation method of the electrolyte is similar to that in Example 1, except that it does not contain liquid electrolyte, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the electrolyte are detailed in Table 2.

[0167] Comparative Examples 2-4

[0168] The preparation method of the electrolyte is similar to that in Example 1, except that the type of ionic liquid used is different, as detailed in Table 1. The thickness, areal density, porosity, and pore size distribution of the electrolyte are detailed in Table 2.

[0169] Comparative Examples 5-8

[0170] Dry film formation was employed: a solid electrolyte membrane was prepared by dry rolling by combining a solid electrolyte with a binder. See Table 1 for details. Table 2 details the thickness, areal density, porosity, and pore size distribution of the electrolyte.

[0171] Table 2. Physical parameters and performance of the composite electrolytes in Examples 1-27 and the electrolytes in Comparative Examples 1-8.

[0172] Performance testing

[0173] Performance testing of composite electrolytes

[0174] AC internal resistance and ionic conductivity testing of composite electrolytes: Impedance analysis was performed on the composite solid electrolyte membrane to obtain the ionic conductivity value of the electrolyte. Specifically, the composite solid electrolyte was pressed into a tablet and placed into a mold sleeve at 25°C, pressurized to 350 MPa, and AC impedance spectroscopy was performed using an impedance analyzer. The ionic conductivity of the electrolyte material was calculated based on the impedance value.

[0175] Tensile strength test: Cut the sample into a strip with a width of 15mm and a length of not less than 100mm. Set the initial distance between the clamps to 100±1mm. Place both ends of the sample into the upper and lower ends of the clamps in sequence and clamp the clamps. During the process, ensure that the sample and the clamps are in the same vertical direction and that the force is uniform with no obvious tensile deformation. After preparation, perform the tensile strength test at a rate of 250mm / min.

[0176] The performance of the composite electrolyte is detailed in Table 2. As can be seen from Table 2, the addition of liquid electrolyte to the composite electrolyte in this application can improve the ionic conductivity and reduce the AC internal resistance, while ensuring a certain mechanical strength.

[0177] Battery cell performance testing

[0178] Next, the composite electrolyte prepared above will be assembled into a battery cell, and its impact on the performance of the battery cell will be tested.

[0179] The battery cells are assembled based on the mold battery (inner diameter Ф=10mm). Each battery cell consists of a positive electrode, an electrolyte layer, and a negative electrode.

[0180] Positive electrode: By mass percentage, the positive electrode composition includes 75 parts NCM811, 20 parts sulfide solid electrolyte, 2 parts VGCF, and 4 parts binder, prepared by the following method: A planetary mixer is used, and a wet mixing process is employed to first apply the binder as a binder. After the binder solution is prepared, the remaining materials are added and stirred until homogeneous, resulting in a positive electrode slurry with a solid content of 65%. Then, a transfer coating method is used to coat the positive electrode slurry at a loading capacity of 5 mAh / cm³. 2 The coating and baking process yields the positive electrode roll. Finally, a roller press is used to compact the positive electrode roll to a density of 3.5 g / cm³. 3 Rolling is performed. The positive electrode roll is then cut to obtain the positive electrode sheet.

[0181] Electrolyte layer: The composite electrolytes of Examples 1-27 and the electrolytes of Comparative Examples 1-8.

[0182] Negative electrode: By mass percentage, the negative electrode composition includes 98 parts silicon-carbon and 2 parts binder. It is prepared using the following method: A planetary mixer is used, and a wet mixing process is employed to first apply the binder as a binder. After the binder solution is prepared, the remaining materials are added and stirred until homogeneous, resulting in a negative electrode slurry with a solid content of 50%. Then, a transfer coating method is used to coat the negative electrode slurry at a loading capacity of 6 mAh / cm³. 2 The coating and baking process yields the negative electrode coil. Finally, a roller press is used to compact the negative electrode coil to a density of 1.5 g / cm³. 3 Roll forming is performed. The negative electrode roll is then cut to obtain the negative electrode sheet.

[0183] Testing of individual battery cells

[0184] Electrochemical performance testing: The operating voltage range of the battery cells was set to 2.6V–4.3V. Cyclic testing was conducted using a constant current charge-discharge method to obtain the first-cycle discharge specific capacity, first-cycle coulombic efficiency, and capacity retention after 100 cycles. The test current was 0.1C (current density 0.5 mA / cm²). 2 ), 0.5C or 1C, the test temperature is 60℃.

[0185] Rate testing: A single battery cell was fully charged to 4.3V using a 0.1C constant current charging method, allowed to rest for 5 minutes, and then discharged to 2.6V using a 0.1C method, recording the initial discharge capacity C0. This process was repeated twice, with discharge currents of 0.5C and 1C respectively, and the discharge capacity under both current conditions was recorded as C. 0.5 C1; C 0.5 / C0 and C1 / C 0.5 This refers to the capacity retention rate under different discharge rates, with the test temperature at 60℃.

[0186] The performance of the battery cells is detailed in Table 3. As can be seen from Table 3, the use of composite electrolyte in the battery cells of this application can improve the rate performance and cycle stability of the battery cells.

[0187] Table 3. Performance of battery cells prepared with composite electrolytes in Examples 1-27 and battery cells prepared with electrolytes in Comparative Examples 1-8.

[0188] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery cell, comprising: A positive electrode, a composite electrolyte, and a negative electrode are provided. The composite electrolyte includes a solid electrolyte sheet and a liquid electrolyte. The solid electrolyte sheet is disposed between the positive electrode and the negative electrode. The solid electrolyte sheet includes a solid electrolyte and a plurality of pores. The liquid electrolyte can permeate into the pores. In the composite electrolyte, the mass percentage of the solid electrolyte is A, the mass percentage of the liquid electrolyte is B, and the mass percentages of the solid electrolyte and the liquid electrolyte satisfy: 5 ≤ A / B ≤ 950.

2. The battery cell of claim 1, wherein, The mass percentage of the solid electrolyte and the liquid electrolyte in the composite electrolyte satisfies the following condition: 20 ≤ A / B ≤ 30.

3. The battery cell of claim 1 or 2, wherein, In the composite electrolyte, the mass percentage A of the solid electrolyte satisfies: 85% ≤ A ≤ 98%; and the mass percentage B of the liquid electrolyte satisfies: 0.1% ≤ B ≤ 15%.

4. The battery cell according to any one of claims 1 to 3, wherein, In the composite electrolyte, the mass percentage A of the solid electrolyte satisfies: 90% ≤ A ≤ 94%; and the mass percentage B of the liquid electrolyte satisfies: 1% ≤ B ≤ 5%.

5. The battery cell of any one of claims 1-4, wherein, The liquid electrolyte includes liquid metals and / or ionic liquids.

6. The battery cell of claim 5, wherein, The liquid metal includes one or more gallium-based liquid metals, and the ionic liquid includes one or more of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, and lithium-tetraethylene glycol dimethyl ether-bis(trifluoromethanesulfonyl)imide salt prepared by mixing lithium bis(trifluoromethylxanthyl)imide and tetraethylene glycol dimethyl ether in a molar ratio of 1:

1.

7. The battery cell according to any one of claims 1 to 6, wherein, The composite electrolyte also includes a binder, wherein the mass percentage of the binder in the composite electrolyte is C, and the mass percentage of the solid electrolyte and the binder satisfies: 20 ≤ A / C ≤ 200.

8. The battery cell of claim 7, wherein, The adhesive includes one or more of polyvinyl alcohol, polyethylene oxide, sodium carboxymethyl cellulose, butadiene rubber, silicone rubber, styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, styrene-ethylene-butene-benzene copolymer, polyvinylidene fluoride-hexafluoropropylene, nitrile rubber, and hydrogenated nitrile rubber.

9. The battery cell according to any one of claims 1 to 8, wherein, The composite electrolyte also includes a dispersant, wherein the mass percentage of the dispersant in the composite electrolyte is D, and the mass percentage of the solid electrolyte and the dispersant satisfies: 100≤A / D≤950.

10. The battery cell of claim 9, wherein, The dispersant includes one or more of polyvinyl alcohol, polyacrylamide, polyether-modified siloxane, fluorocarbon-modified acrylic resin, and polyvinylpyrrolidone.

11. The battery cell according to any one of claims 1 to 10, wherein, The solid electrolyte includes one or more of oxide solid electrolytes, halide solid electrolytes, sulfide solid electrolytes, and polymer solid electrolytes.

12. The battery cell according to any one of claims 1 to 11, wherein, The composite electrolyte further includes a porous polymer support, and the solid electrolyte sheet is disposed on at least one side surface of the porous polymer support or in the pores of the porous polymer support. The thickness ratio of the composite electrolyte to the porous polymer support is 12:1 to 1:

1.

13. The battery cell of claim 12, wherein, The porous polymer support includes one or more of the following: propylene fiber, polyester fiber, nylon fiber, polyethylene fiber, and bio-based materials.

14. The battery cell of any one of claims 1-13, wherein, The composite electrolyte satisfies at least one of the following conditions: The thickness of the composite electrolyte is 5 μm to 60 μm; The areal density of the composite electrolyte is 0.5 mg / cm 2 ~ 18 mg / cm 2 ; The porosity of the composite electrolyte is 1%-15%; The composite electrolyte has a pore size distribution of 0.1 μm to 100 μm.

15. The battery cell of any one of claims 1-14, wherein, The composite electrolyte satisfies at least one of the following conditions: The ionic conductivity of the composite electrolyte is 0.1 mS / cm to 10 mS / cm; The tensile strength of the composite electrolyte is 0.2 MPa to 30 MPa; The internal resistance of the composite electrolyte is 0.76Ω to 6.4Ω.

16. The battery cell according to any one of claims 1 to 15, wherein, The battery cell satisfies at least one of the following conditions: The current is 0.1C, and the first-cycle discharge specific capacity of the battery cell is 160mAh / g to 400mAh / g; With a current of 0.1C, the capacity retention rate of the battery cell after 100 cycles is 80% to 100%.

17. A composite electrolyte for a battery cell, the composite electrolyte comprising a solid electrolyte sheet and a liquid electrolyte, the solid electrolyte sheet being disposed between a positive electrode and a negative electrode, the solid electrolyte sheet comprising a solid electrolyte and a plurality of pores, the liquid electrolyte being permeable to the pores, wherein the mass percentage of the solid electrolyte in the composite electrolyte is A, the mass percentage of the liquid electrolyte is B, and the mass percentages of the solid electrolyte and the liquid electrolyte satisfy: 9 ≤ A / B ≤ 950.

18. A battery device comprising a plurality of battery cells as described in any one of claims 1 to 16 or a plurality of battery cells formed by preparing the composite electrolyte as described in claim 17.

19. An electrical device comprising the battery device of claim 18.

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