Electrode assembly, battery and electric equipment

Abstract

The invention relates to the technical field of batteries, in particular to an electrode assembly, a battery and electric equipment. The provided electrode assembly comprises a positive plate, a negative plate and a diaphragm arranged between the positive plate and the negative plate, the positive plate comprises a positive active material, and the positive active material comprises an oxide containing transition metal ions; the diaphragm comprises a base membrane and a coating arranged on the surface of at least one side of the base membrane, the coating comprises a solid electrolyte and a binder, the binder comprises a protein binder with a functional group, and the functional group comprises at least one of hydroxyl, carboxyl, amido or acylamino; and the coating close to one side of the positive plate also contains a complex of functional groups and transition metal ions. A battery includes the provided electrode assembly. The power performance of the electrode assembly can be improved, the internal resistance is reduced, and the high-temperature storage and circulation internal resistance increasing performance of the battery is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and more particularly, to an electrode assembly, a battery, and an electrical device. Background Art

[0002] In recent years, the low-altitude economy has witnessed rapid development. Currently, electric vertical takeoff and landing vehicles (eVTOLs) are regarded as the best carriers for the low-altitude economy. Thanks to the electrification + multi-rotor design, the safety of eVTOLs is more than 10 times that of helicopters; at the same time, the noise is lower, and the cruising noise is only half of that of helicopters; moreover, the comprehensive operating cost is 20% lower than that of helicopters. However, compared with electric vehicles, eVTOLs have higher requirements for high-performance batteries, with an energy density exceeding 280 Wh / kg, a peak discharge power exceeding 8C at low SOC, and greater challenges for fast charging and safety performance.

[0003] Regarding the requirements of eVTOLs for both high energy density and high power, the traditional high-nickel ternary + silicon-carbon anode system is difficult to meet the requirements. The main obstacles include the following three points: (1) In the separator, the traditional alumina-coated separator is difficult to meet the initial power requirements. (2) In the cathode material, the oxidation of the cathode material at high voltage and high temperature easily causes an increase in the acidity of the electrolyte, which in turn leads to continuous dissolution of metals. To alleviate this problem, the traditional approach is to introduce cathode protection additives into the electrolyte, but this approach will cause an increase in impedance, which does not meet the requirements of eVTOLs. (3) The application of silicon-carbon anodes causes the impedance of the anode to continuously increase during use, and this increase is mainly due to an increase in the acidity of the electrolyte and the continuous deposition of transition metal elements on the anode.

[0004] Therefore, to solve the above problems, it is necessary to develop an effective technical solution that can reduce the internal resistance of the battery and improve the high-temperature storage and cycle internal resistance growth performance of the battery while ensuring the improvement of the power performance of eVTOLs. Summary of the Invention

[0005] In view of this, the present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, the present invention provides an electrode assembly, a battery, and an electrical device, which can improve the power performance of the electrode assembly, reduce the internal resistance, and effectively improve the high-temperature storage and cycle internal resistance growth performance of the battery.

[0006] To solve the above technical problems, the present application is implemented as follows:

[0007] According to one aspect of the present application, the present application provides an electrode assembly, which includes a positive electrode sheet, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet;

[0008] The positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes an oxide containing transition metal ions;

[0009] The separator includes a base film and a coating provided on at least one surface of the base film. The coating includes a solid electrolyte and a binder. The binder includes a protein-based binder having functional functional groups, and the functional functional groups include at least one of a hydroxyl group, a carboxyl group, an amino group, or an amide group;

[0010] The coating located on the side close to the positive electrode sheet further contains a complex of the functional functional group and the transition metal ion.

[0011] In some embodiments thereof, the amino acid content in the protein-based binder is ≥70%.

[0012] In some embodiments thereof, the relative molecular weight of the protein-based binder is 3 to 300 kDa.

[0013] In some embodiments thereof, the protein-based binder includes at least one of bone glue, gelatin, bean gum, or sericin.

[0014] In some embodiments thereof, the transition metal ions include at least one of nickel ions, cobalt ions, manganese ions, copper ions, zirconium ions, titanium ions, iron ions, or tungsten ions.

[0015] In some embodiments thereof, the chemical formula of the positive electrode active material is LiNi x Co y M 1-x-y O2, where M includes at least one of Mn, Al, Mg, Zr, Ti, Cu, Fe, W, or B, 0.7 ≤ x ≤ 1.0, and 0 ≤ y ≤ 0.3.

[0016] In some embodiments thereof, the solid electrolyte includes an oxide solid electrolyte.

[0017] In some embodiments thereof, the solid electrolyte includes at least one of a NASCION-type solid electrolyte, a LISCION solid electrolyte, a garnet-type solid electrolyte, or a perovskite-type solid electrolyte.

[0018] In some embodiments thereof, the ionic conductivity of the solid electrolyte is 10 -3 ~10 -5 S / cm.

[0019] In some embodiments thereof, the average particle size of the solid electrolyte is 500 nm to 1500 nm.

[0020] In some of these embodiments, the mass ratio of the solid electrolyte to the binder is (80 to 95):(5 to 20).

[0021] In some of these embodiments, the binder further includes a silane coupling agent.

[0022] In some of these embodiments, the silane coupling agent includes at least one of vinyl silane, amino silane, epoxy silane, mercapto silane, or methacryloxy silane.

[0023] In some of these embodiments, the mass ratio of the protein-based binder to the silane coupling agent is (0.5 to 2):1.

[0024] In some of these embodiments, the base film includes at least one of polyethylene, polypropylene, polyethylene terephthalate, non-woven fabric, or aramid.

[0025] In some of these embodiments, the porosity of the base film is 35% to 55%.

[0026] In some of these embodiments, the porosity of the coating is 50% to 70%.

[0027] In some of these embodiments, the thickness of the base film is 2 μm to 18 μm.

[0028] In some of these embodiments, the pore size range of the base film is 20 nm to 60 nm.

[0029] In some of these embodiments, the thickness of the coating is 1 μm to 5 μm.

[0030] In some of these embodiments, the ratio of the thickness of the coating to the thickness of the base film is 0.05 to 0.5.

[0031] In some of these embodiments, the thickness of the separator is 5 μm to 20 μm.

[0032] In some of these embodiments, the area of the separator is larger than the area of the negative electrode sheet, and the area of the negative electrode sheet is larger than the area of the positive electrode sheet.

[0033] In some of these embodiments, the distance between the edge of the separator and the edge of the negative electrode sheet is 0.5 to 5 mm.

[0034] In some of these embodiments, the distance between the edge of the negative electrode sheet and the edge of the positive electrode sheet is 0.5 to 3 mm.

[0035] According to another aspect of the present application, the present application provides a battery, and the battery includes the aforementioned electrode assembly.

[0036] According to another aspect of the present application, the present application provides an electrical device, which includes the aforementioned electrode assembly or includes the aforementioned battery.

[0037] Implementing the technical solution of the present invention has at least the following beneficial effects:

[0038] In the present application, the provided electrode assembly includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet. The separator includes a base film and a coating provided on the base film. The binder in the coating includes a protein-based binder having functional functional groups, and the functional functional groups include at least one of hydroxyl group, carboxyl group, amino group, or amide group. The protein-based binder having functional functional groups can form a complex with transition metal ions in the positive electrode sheet. Thus, by enabling the protein-based binder having functional functional groups to form a complex with transition metal ions in the positive electrode sheet, these transition metal ions can be prevented from diffusing to the negative electrode side to damage the SEI film, reducing the increase in internal resistance during high-temperature cycling and storage, facilitating the reduction of the internal resistance of the battery, and improving the high-temperature storage performance and cycling performance of the battery. Moreover, the protein-based binder can swell in the electrolyte to lock the residual electrolyte, which can further improve the battery safety. Furthermore, the solid electrolyte in the coating has a high ionic conductivity, which can reduce the initial internal resistance of the battery and ensure the performance of high power.

[0039] In a preferred embodiment of the present application, the binder in the coating of the separator further includes a silane coupling agent; the introduction of the silane coupling agent can not only improve the wetting effect between the separator and the solid electrolyte, avoid the phenomenon of demolding and material dropping, and improve the bonding strength; at the same time, due to the electrophilicity of silicon (Si) in the silane, it can complex with the acid formed in the electrolyte to reduce the corrosion of the positive and negative electrode materials by the acid. Through the complexation of transition metals by the protein-based binder and the complexation of acid by the silane coupling agent, the function of high-impedance electrolyte additives in the positive electrode can be effectively replaced, avoiding the use of high-impedance additives and ensuring the power performance of the battery.

[0040] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The figure shows a schematic structural diagram of an electrode assembly provided by an embodiment of the present invention;

[0042] Figure 2 The figure shows a schematic diagram of the principle of complexation of transition metal ions by a protein-based binder provided by some embodiments of the present invention;

[0043] Figure 3The figure shows a schematic diagram of the improvement of the wetting effect by the silane coupling agent provided by some embodiments of the present invention.

[0044] Description of the reference numerals:

[0045] 10 - positive electrode sheet;

[0046] 20 - separator; 210 - base film; 220 - coating;

[0047] 30 - negative electrode sheet. Detailed implementation manners

[0048] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments of the present application are only used to illustrate the present application and not to limit the scope of the present application.

[0049] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range or individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0050] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions. If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0051] If there is no special description, the "including" and "comprising" mentioned in the present application mean open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or only the components listed can be included or comprised.

[0052] In the related art, with the development of clean energy, more and more devices use electric energy as the driving energy. As a result, batteries such as lithium batteries that can store a large amount of electric energy and can be repeatedly charged and discharged have developed rapidly. Among them, batteries are not only applied to energy storage power systems such as hydropower, thermal power, wind power, and solar power stations, but also widely used in electric transportation means such as electric vehicles, electric bicycles, and electric motorcycles, as well as multiple fields such as aerospace and military equipment. The inventor noticed that although the application scope of batteries is getting wider and wider, the requirements for various battery performances are also getting higher and higher. For example, an electric vertical take-off and landing (eVTOL) vehicle that uses a battery as the driving force has higher requirements for high-performance batteries. There are still some problems with the batteries used in eVTOL in the prior art. For example, the separator in traditional batteries is difficult to meet the initial power requirements, and the method used to improve the acidity increase of the electrolyte easily causes problems such as an increase in impedance. Therefore, on the basis of ensuring the improvement of the battery power performance in eVTOL, both the internal resistance of the battery is reduced, and the high-temperature storage and cyclic internal resistance growth performance of the battery are improved. As an important component of a lithium battery, the properties of the separator are closely related to the high performance of the lithium battery. Especially in high-power and high-energy-density lithium batteries, the performance requirements for the separator are more obvious. Therefore, providing a high-performance separator is crucial for improving the related performance of the battery.

[0053] In view of the above technical problems, from the perspective of improving the performance of the separator, the embodiments of the present application propose a separator with a coating having excellent electrochemical performance, an electrode assembly including the separator, a battery including the electrode assembly, and an electrical device including the electrode assembly, in order to achieve the purpose of reducing the internal resistance of the battery and improving the high-temperature storage and cyclic internal resistance growth performance of the battery on the basis of ensuring the battery power performance.

[0054] Therefore, the following technical solutions are proposed.

[0055] In a first aspect, as Figure 1 shown, some embodiments of the present application provide an electrode assembly, which includes a positive electrode sheet 10, a negative electrode sheet 30, and a separator 20 disposed between the positive electrode sheet 10 and the negative electrode sheet 30;

[0056] The positive electrode sheet 10 includes a positive electrode active material, and the positive electrode active material includes an oxide containing transition metal ions;

[0057] The separator 20 includes a base film 210 and a coating 220 disposed on at least one surface of the base film 210 in the thickness direction. The coating 220 includes a solid electrolyte and a binder, and the binder includes a protein-based binder having functional functional groups. The functional functional groups include at least one of a hydroxyl group, a carboxyl group, an amino group, or an amide group;

[0058] The coating 220 located on the side close to the positive electrode sheet 10 further contains a complex of a functional functional group and a transition metal ion.

[0059] In the above electrode assembly, the separator 20 is a composite separator, which has a multi-layer structure, including a base film 210 and a coating 220 arranged in a stacked manner. The above "the coating 220 is disposed on at least one surface of the base film 210 in the thickness direction" means that the coating 220 can be disposed on one surface of the base film 210 in its own thickness direction, or can be disposed on two surfaces of the base film 210 in its own thickness direction. Here, the "surface" can be the entire area of the base film 210, or can be a partial area of the base film 210. For example, in this embodiment, the surface can be the entire area of the base film 210. The present application has no special limitation on this, as long as the purpose of the present application can be achieved.

[0060] As an example, the base film 210 has two surfaces opposite to each other in its own thickness direction. In some embodiments, the coating 220 is disposed on two opposite surfaces of the base film 210, that is, the coating 220 is disposed on both surfaces close to the positive electrode side and the negative electrode side. Or, in other embodiments, the coating 220 is disposed on one of the surfaces of the base film 210, and the coating 220 is disposed close to the positive electrode. That is, the coating 220 on the separator 20 of the present application can be disposed on both surfaces of the base film 210, or can be disposed on one surface of the base film 210. When the coating 220 is only disposed on one surface of the base film 210, the coating 220 is disposed on the side close to the positive electrode.

[0061] In the above electrode assembly, the positive electrode active material in the positive electrode sheet 10 contains transition metal elements, and a certain amount of transition metal ions can be dissolved out under acid corrosion. Optionally, the transition metal ions can include various common transition metal ions used in the positive electrode active material.

[0062] The coating 220 of the separator 20 of the above electrode assembly contains a solid electrolyte and a binder. Among them, the binder can include an organic material having a binding property, which is used to enhance the adhesion between the separator 20 and the electrode sheet to improve the electrochemical or kinetic performance of the battery. In the coating 220 of the separator 20 of the embodiment of the present application, the binder includes a protein-based binder having a functional functional group, where the functional functional group includes at least one of a hydroxyl group, a carboxyl group, an amino group or an amide group; preferably, the functional functional group includes at least one or two of a hydroxyl group or a carboxyl group. The above functional functional group can complex with the transition metal ions in the positive electrode sheet 10 to form a complex.

[0063] Thus, in the embodiments of the present application, by forming a complex between a protein-based binder with functional functional groups and transition metal ions in the positive electrode sheet 10, these transition metal ions can be prevented from diffusing to the negative electrode side to damage the SEI film, reducing the increase in internal resistance during high-temperature cycling and storage, facilitating the reduction of the internal resistance of the battery, and improving the high-temperature storage performance and cycling performance of the battery. Moreover, the protein-based binder can swell in the electrolyte to lock the residual electrolyte, further improving the battery safety. In addition, the coating 220 of the separator 20 also contains a solid electrolyte with a high ionic conductivity, which can reduce the initial internal resistance of the battery and ensure the high-power performance.

[0064] In a preferred embodiment of the present invention, the binder in the coating 220 of the separator 20 further includes a silane coupling agent, that is, the composition of the coating 220 can be mainly formed by a solid electrolyte, a protein-based binder with functional functional groups, and a silane coupling agent.

[0065] Thus, the coating 220 of the separator 20 of the present invention adopts a composite method of a protein-based binder, a silane coupling agent, and an oxide solid electrolyte, and the coating 220 is arranged facing the positive electrode sheet 10 when assembling the battery, which can achieve the effect of reducing the internal resistance of the battery and improving the high-temperature storage and cycling internal resistance growth performance of the battery while ensuring the power performance of the battery. Specifically:

[0066] In the coating 220 of the separator 20, the solid electrolyte has a high lithium ion conductivity, which can reduce the initial internal resistance of the battery and ensure the high-power performance; and improve the thermal shrinkage performance of the separator and improve the battery safety. The protein-based binder contains abundant polar functional groups such as hydroxyl and carboxyl groups, which can complex with transition metal ions to prevent them from diffusing to the negative electrode side to damage the SEI film, reducing the increase in internal resistance during high-temperature cycling and storage. Moreover, the protein-based binder can swell in the electrolyte, that is, the branched and crosslinked state of the polymer protein-based binder unfolds when encountering the electrolyte, releasing more functional groups, which can form hydrogen bonds with the electrolyte, thereby locking the residual electrolyte and further improving the battery safety. Further, in order to improve the poor wettability between the single protein-based binder and the solid electrolyte (such as oxide solid electrolyte) and the separator, and the problem of demolding and material dropping caused by the complexation of active bonds during use, the embodiments of the present invention also add a silane coupling agent to the coating 220. The introduction of this silane coupling agent can not only improve the wetting effect between the separator and the solid electrolyte, prevent demolding and material dropping, and improve the bonding strength; at the same time, due to the electrophilicity of silicon (Si) in the silane, it can complex with the acid formed in the electrolyte, reducing the corrosion of the positive and negative electrode materials by the acid. For example, the reaction of lithium hexafluorophosphate (LiPF6) in the electrolyte: LiPF6 → LiF + PF5 - , this reaction is a reversible reaction that always exists in the battery. In addition, PF5 -It cannot stably exist in the electrolyte and will further decompose, showing strong acidity. The acidic decomposition products will further corrode the cathode material, further produce acid, and also be consumed to form SEI at high negative electrode potentials. Therefore, by complexing silicon with the acid in the electrolyte, that is, using the electrophilicity of Si itself to complex with the acid in the electrolyte to produce complex products, the corrosion of the cathode and anode materials by the acid can be reduced. Moreover, by complexing transition metals with protein binders and complexing acids with silane coupling agents, the functions of high-impedance electrolyte additives in the cathode can be effectively replaced, avoiding the use of high-impedance additives and ensuring the power performance of the battery.

[0067] Thus, through the combined use of protein binders, silane coupling agents, and solid electrolytes in the coating 220 of the separator 20 in the present invention, the internal resistance of the battery is reduced, the high-temperature storage and high-temperature cycling performance are improved, the increase in internal resistance at high temperatures is reduced, and at the same time, the battery safety performance is improved, which is beneficial to the application of high specific energy battery systems in the eVTOL field with strong high-power requirements.

[0068] The inventors of the present invention have found through in-depth research that when the electrode assembly of the present application meets the above design conditions, if one or more of the following conditions are also optionally met, the performance of the electrode assembly can be further improved.

[0069] In some embodiments, the amino acid content in the protein binder ≥ 70%. As an example, the amino acid content in the protein binder can be 70%, 72%, 75%, 78%, 80%, 85%, 90%, 95% or greater than 95%, etc.

[0070] In the above-mentioned coating 220 of the separator 20, the amino acid content in the protein binder needs to be not less than 70%, so as to provide sufficient amino acids to complex with transition metal ions and effectively prevent the transition metals from diffusing to the negative electrode side and damaging the SEI film. If the amino acid content in the protein binder is less than 70%, there will not be enough amino groups to complex with transition metal ions, and the deposition of transition metals on the negative electrode cannot be avoided.

[0071] Optionally, the above-mentioned amino acids can include various amino acids such as serine, glycine, aspartic acid, alanine, tryptophan, etc.

[0072] In some embodiments, the relative molecular weight of the protein-based binder is 3 to 300 kDa; by way of example, the relative molecular weight of the protein-based binder is any one of 3 kDa, 5 kDa, 10 kDa, 20 kDa, 50 kDa, 100 kDa, 150 kDa, 200 kDa, 300 kDa or the range value between any two of them. If the molecular weight of the protein-based binder is too small, it cannot provide effective bonding performance. If the molecular weight of the protein-based binder is too large, the resulting separator will be too hard to form a battery. Therefore, the present invention controls the relative molecular weight of the protein-based binder within 3 to 300 kDa, which can provide good bonding performance and make the hardness of the resulting separator moderate.

[0073] In some embodiments, the protein-based binder includes, but is not limited to, any one or a combination of at least two of bone glue, gelatin, bean gum or sericin. Typical but non-limiting combinations include the combination of bone glue and gelatin, the combination of bone glue and bean gum, the combination of bone glue and sericin, the combination of bone glue, gelatin and bean gum, the combination of gelatin and bean gum, the combination of gelatin and sericin, the combination of gelatin, bean gum and sericin, etc.

[0074] In the above embodiments, several specific protein-based binders are listed, and those skilled in the art can select one or several of them according to the implementation needs. The several protein-based binders provided have good bonding effects and contain rich polar functional groups such as hydroxyl groups and carboxyl groups, which can be used for complexing with transition metal ions, facilitating the reduction of the increase in internal resistance during high-temperature cycling and storage; in addition, the above several protein-based binders are stable in a certain voltage range, can swell in the electrolyte, lock the residual electrolyte, and further improve the battery safety.

[0075] In the present application, the binder in the coating 220 of the separator 20 includes not only the above-mentioned protein-based binder but also a silane coupling agent. Specifically, in some embodiments, the silane coupling agent includes, but is not limited to, any one or a combination of at least two of vinyl silane, amino silane, epoxy silane, mercapto silane or methacryloxy silane. Typical but non-limiting combinations include the combination of vinyl silane and amino silane, the combination of vinyl silane and epoxy silane, the combination of vinyl silane and mercapto silane, the combination of amino silane and epoxy silane, the combination of epoxy silane and methacryloxy silane, the combination of epoxy silane, mercapto silane and methacryloxy silane, etc.

[0076] In the above embodiments, several specific silane coupling agents are listed, and those skilled in the art can select one or several of them according to the implementation needs. The above several silane coupling agents have good bonding effects, can be used to alleviate the poor wettability between the separate protein-based binder and the oxide solid electrolyte and the separator, and can easily cause demolding and material dropping phenomena due to the complexation of active bonds during use, and can improve the bonding strength; in addition, due to the electrophilicity of Si in the silane, it can complex with the acid formed in the electrolyte to reduce the corrosion of the positive and negative electrode materials by the acid.

[0077] It should be noted that the present application does not limit the specific types of the above vinyl silanes, amino silanes, epoxy silanes, etc., and those skilled in the art can select any vinyl silanes, amino silanes, epoxy silanes, etc. known in the prior art according to actual needs. As an example, vinyl silanes can include, but are not limited to, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(β-methoxyethoxy)silane, etc. Epoxy silanes can include, but are not limited to, β-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexane)ethyltrimethoxysilane, glycidoxypropyltrimethoxysilane, 3-epoxypropoxypropyldimethylethoxysilane, 3-(2,3)-epoxypropylmethyldimethoxymethylsilane, 3-(2,3)epoxypropoxypropyltrimethoxysilane, etc. Amino silanes can include, but are not limited to, aminopropyltrimethoxysilane, phenylaminomethyltrimethoxysilane, aminoethylaminopropyltrimethoxysilane, polyaminoalkyltrialkoxysilane, etc.

[0078] Preferably, the silane coupling agent includes a C-Y bond, and the C-Y bond refers to the organic group in the silane, such as one or two of vinyl silane or epoxy silane, and the Y group therein can be a vinyl group or an epoxy group. The organic group in vinyl silane or epoxy silane can be well connected to the solid electrolyte, improve the bonding effect between the protein-based binder and the solid electrolyte, and further enhance the adhesiveness of the separator coating. Therefore, it is more preferable to use vinyl silane or epoxy silane as the silane coupling agent.

[0079] In some embodiments, the mass ratio of the protein-based binder to the silane coupling agent is (0.5-2):1. As an example, the mass ratio of the protein-based binder to the silane coupling agent can be 0.5:1, 0.8:1, 1:1, 1.5:1, 2:1, etc. According to the mass ratio of the protein-based binder to the silane coupling agent of (0.5-2):1, dispersing the binder in such a ratio in the coating to form the separator 20 can make the overall adhesiveness and stability of the separator 20 better, can improve the wetting effect between the separator and the solid electrolyte, and is also beneficial to ensuring the power performance of the battery, thereby enhancing the comprehensive effect of the structural stability of the battery.

[0080] In this application, the coating 220 of the separator 20 includes not only the above-mentioned binder but also a solid electrolyte. Specifically, in some embodiments, the solid electrolyte includes an oxide solid electrolyte. The oxide solid electrolyte has a high lithium-ion conductivity, which can reduce the initial internal resistance of the battery and ensure the performance of high power.

[0081] In some embodiments, the solid electrolyte includes, but is not limited to, any one or at least two combinations of NASCION-type solid electrolytes, LISCION solid electrolytes, garnet-type solid electrolytes, or perovskite-type solid electrolytes.

[0082] In the above embodiments, several specific solid electrolytes are listed, and those skilled in the art can select one or several of them according to the implementation needs. The above several oxide solid electrolytes have a high lithium-ion conductivity, which can reduce the initial internal resistance of the battery and ensure the performance of high power; in addition, the above several solid electrolytes also have good heat resistance and still have strong structural stability at higher temperatures. Therefore, the heat resistance and structural stability of the separator can be further improved, thereby enhancing the comprehensive effect of the structural stability of the battery.

[0083] It should be noted that the solid electrolyte includes, but is not limited to, the several substances listed above, and those skilled in the art can select the oxide solid electrolytes known in the prior art according to actual needs.

[0084] In some embodiments, the ionic conductivity of the solid electrolyte is 10 -3 ~10 -5 S / cm. As an example, the ionic conductivity of the solid electrolyte can be any one of the point values of 10 -3 S / cm, 10 -4 S / cm, 10 -5 S / cm or the range value between any two of them.

[0085] In some embodiments, the average particle size of the solid electrolyte is 500nm to 1500nm. As an example, the average particle size of the solid electrolyte can be any one of the point values of 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1200nm, 1500nm or the range value between any two of them.

[0086] In this application, the average particle size can be understood as the equivalent diameter. The application does not particularly limit the regulation method of the average particle size of the solid electrolyte, as long as the purpose of this application can be achieved. For example, it can be achieved by directly purchasing a solid electrolyte with an average particle size within the range of this application, or by means of crushing, grinding or ball milling.

[0087] It should also be noted that in this application, the average particle size or particle size can be measured by any known method in the art, and there is no limitation thereto. For example, the average particle size can be measured by a Malvern high-sensitivity nanoparticle size analyzer.

[0088] In some embodiments, in the coating 220 of the separator 20, the mass ratio of the solid electrolyte to the binder is (80-95):(5-20). As an example, the mass ratio of the solid electrolyte to the binder can be 80:20, 85:15, 90:10, 95:5, etc.

[0089] As described above, the mass ratio of the solid electrolyte to the binder affects the final thermal performance, structural stability, and adhesiveness of the composite separator. By setting the solid electrolyte and the binder in such a ratio of (80-95):(5-20) in the coating to form a separator, the functions of the solid electrolyte and the binder, that is, the combined use of the solid electrolyte, the protein-based binder, and the silane coupling agent, can be fully exerted, so that the overall adhesiveness, stability, and thermal performance of the separator are better, which is beneficial to ensuring the power performance of the battery, ensuring the transmission of lithium ions, and thus improving the comprehensive effect of the structural stability of the battery.

[0090] In some embodiments, in the base film 210 of the separator 20, the base film 210 includes, but is not limited to, at least one of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), non-woven fabric, or aramid. As an example, the base film 210 can be selected from any one or at least two combinations of a PE film, a PP film, a PET film, a non-woven fabric, and aramid.

[0091] Selecting the base film 210 of the above types is more conducive to the transmission of the electrolyte, making the wettability and absorption rate of the separator for the electrolyte relatively high, so as to improve the cycle performance and safety performance of the battery.

[0092] The base film 210 in the separator 20 generally has good chemical and thermal stability, appropriate porosity and pore size, and good mechanical strength. Base films such as polyolefin materials and polyester materials not only have good insulation properties, but also can form a microporous structure, which can endow the separator with the air permeability and porosity required by the industry, thereby providing a good migration channel for the ions of the electrolyte and enabling the battery to operate stably and efficiently. Therefore, the above base film materials can be used as the materials for the separator substrate.

[0093] It should be noted that the base film 210 includes but is not limited to the several materials listed above, and those skilled in the art can select any base film known in the prior art according to actual needs. For example, the base film can also be at least one of base films such as a PMMA film, a PVDF film, and a PTFE film.

[0094] In some embodiments, the porosity of the base film 210 is 35% to 55%. As an example, the porosity of the base film 210 can be 35%, 36%, 37%, 38%, 39%, 40%, 45%, 50%, 55%, etc. Of course, it can also be other values within the above range, which are not limited herein. The base film 210 with a porosity of 35% to 55% can reduce the diffusion impedance and improve the safety of the battery. If the porosity of the base film 210 is less than 35%, it will cause an increase in the diffusion impedance. If the porosity of the base film 210 is greater than 55%, it will easily cause a serious self-discharge phenomenon.

[0095] In some embodiments, the porosity of the coating 220 is 50% to 70%. As an example, the porosity of the coating 220 can be 50%, 55%, 60%, 65%, 70%, etc. Of course, it can also be other values within the above range, which are not limited herein. The coating 220 with a porosity of 50% to 70% can reduce the diffusion impedance and enhance the complexing effect of the binder on the transition metal. If the porosity of the coating 220 is less than 50%, it will cause an increase in the diffusion impedance of the separator. If the porosity of the coating 220 is greater than 70%, it will result in a weakened complexing effect of the binder on the transition metal.

[0096] In some embodiments, the thickness of the base film 210 is 2 μm to 18 μm. Preferably, the thickness of the base film 210 is 3 μm to 16 μm. As an example, the thickness of the base film 210 can be 2 μm, 3 μm, 5 μm, 8 μm, 10 μm, 12 μm, 14 μm, 15 μm, 16 μm, 18 μm. Of course, it can also be other values within the above range, which are not limited herein. Considering obtaining good mechanical properties and internal resistance, the present invention preferably selects the thickness of the base film 210 to be 2 μm to 18 μm, more preferably 3 μm to 16 μm. If the thickness of the base film 210 is too small, the strength will be low, and it cannot support the coating, and the separator cannot be coated. If the thickness of the base film 210 is too large, it will significantly reduce the volumetric energy density of the fabricated battery.

[0097] In some embodiments, the thickness of the coating 220 is 1 μm to 5 μm. As an example, the thickness of the coating 220 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm. Of course, it can also be other values within the above range, which are not limited herein. If the thickness of the coating 220 is less than 1 μm, the coating 220 cannot effectively complex the acid and the dissolved transition metal. If the thickness of the coating 220 is greater than 5 μm, it will significantly reduce the volumetric energy density of the fabricated battery and is more likely to be demolded. Therefore, by controlling the thickness of the coating 220 in the separator 20 to be 1 μm to 5 μm, the present invention can enable the coating to effectively complex the acid and the dissolved transition metal and is conducive to improving the energy density of the battery.

[0098] In some embodiments, the ratio of the thickness of the coating 220 to the thickness of the base film 210 is 0.05 to 0.5. Preferably, the ratio of the thickness of the coating 220 to the thickness of the base film 210 is 0.1 to 0.5. As an example, the ratio of the thickness of the coating 220 to the thickness of the base film 210 is 0.05, 0.1, 0.2, 0.3, 0.4, 0.5. Of course, it can also be other values within the above range, which are not limited herein. If this ratio is too small, the thickness of the coating is too thin to function, such as being unable to effectively complex acids and dissolved transition metals; if this ratio is too large, the strength of the base film cannot support it, and the separator cannot be coated.

[0099] In some embodiments, the thickness of the separator 20 is 5 μm to 20 μm, that is, the total thickness range of the base film 210 and the coating 220 can be 5 μm to 20 μm. As an example, the thickness of the separator 20 can be 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm. Of course, it can also be other values within the above range, which are not limited herein. The separator 20 with a thickness of 5 μm to 20 μm has good mechanical strength and a small thermal shrinkage rate. Such a low-thickness separator used in a battery can significantly improve the battery energy density; that is, by controlling the thickness of the separator within the above range, the mechanical strength and the comprehensive effect of improving the battery energy density in the battery can be good.

[0100] In some embodiments, the pore size range of the base film 210 is 20 nm to 60 nm. As an example, the pore size of the base film 210 can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm. Of course, it can also be other values within the above range, which are not limited herein. When the pore size of the base film 210 is within this range, it is beneficial to obtain sufficient ion permeability, form a separator with a certain air permeability and porosity, and can effectively inhibit battery short circuits.

[0101] It should be noted that the present application does not particularly limit the preparation method of the separator 20, as long as the purpose of the present application can be achieved. For example, the separator 20 can be prepared by the following steps:

[0102] Mix the solid electrolyte and binder (protein binder and silane coupling agent) in the present application in a mass ratio within the scope of the present application to prepare a coating slurry with an appropriate solid content;

[0103] Coat the coating slurry on at least one surface of the base film 210, and dry it to obtain the separator 20.

[0104] In the present application, the positive electrode sheet 10 in the electrode assembly includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material. As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer is provided on either one or both of the two opposite surfaces of the positive electrode current collector.

[0105] Among them, the positive electrode active material includes an oxide containing transition metal ions. For example, in some embodiments, the transition metal ions include at least one of nickel ions, cobalt ions, manganese ions, copper ions, zirconium ions, titanium ions, iron ions or tungsten ions.

[0106] In some embodiments, the chemical formula of the positive electrode active material is LiNi x Co y M 1-x-y O2, where M includes at least one of Mn, Al, Mg, Zr, Ti, Cu, Fe, W or B, 0.7 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.3. In this positive electrode active material, nickel (Ni) accounts for more than 70% of the total metal ratio. Therefore, this positive electrode active material is preferably a high-nickel positive electrode material.

[0107] In the present application, the positive electrode active material includes metal elements, the metal elements include nickel and cobalt, and may also include one or more of metal elements such as manganese, copper, zirconium, titanium, iron, tungsten, etc. Optionally, the positive electrode active material may also contain non-metal elements. For example, the non-metal elements include at least one of phosphorus, boron, silicon or sulfur, and these elements can further improve the stability of the positive electrode active material.

[0108] In the present application, the positive electrode active material is preferably a high-nickel positive electrode material, and more preferably a high-nickel ternary positive electrode material. Preferably, the mass specific energy of the positive electrode active material is greater than 280 Wh / kg. As an example, the above positive electrode active material may be lithium nickel cobalt manganate (such as NCM811), lithium nickel cobalt aluminate, lithium nickel cobaltate, etc.

[0109] In the above embodiments, several specific positive electrode active materials are listed, and those skilled in the art can select one or several of them according to the implementation needs.

[0110] It should be noted that the positive electrode active material includes but is not limited to the several substances listed above, and those skilled in the art can select any positive electrode active material known in the prior art according to actual needs.

[0111] The present application has no particular limitation on the positive electrode current collector, as long as the object of the present application can be achieved. For example, the positive electrode current collector may include aluminum foil, aluminum alloy foil, composite current collector, etc. Among them, the composite current collector can be formed by forming a metal material such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy on a substrate of a polymer material such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.

[0112] In the present application, there is no particular limitation on the thickness of the positive electrode current collector and the positive electrode active material layer, as long as the object of the present application can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 50 μm, preferably 6 μm to 20 μm. The thickness of the single-sided positive electrode active material layer is 20 μm to 150 μm.

[0113] Optionally, the positive electrode active material layer may further include a conductive agent and a binder. The present application has no particular limitation on the types of the conductive agent and the binder in the positive electrode active material layer, as long as the object of the present application can be achieved. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer or fluorinated acrylate resin. As an example, the conductive agent may include at least one of conductive carbon black such as acetylene black and Ketjen black, carbon nanotubes, graphene or carbon nanofibers.

[0114] In some embodiments, the positive electrode sheet 10 can be prepared by the following method: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode sheet 10 can be obtained.

[0115] In some embodiments, the negative electrode sheet 30 includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode material. As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is provided on any one or both of the two opposite surfaces of the negative electrode current collector.

[0116] In this embodiment, for the negative electrode sheet 30, the specific materials, structures, etc. of the negative electrode current collector and the negative electrode active material layer are not limited, and the structures and components of the negative electrode sheet 30 that can be used in secondary batteries known to those skilled in the art can be selected.

[0117] In some embodiments, the area of the separator 20 is larger than the area of the negative electrode sheet 30, and the area of the negative electrode sheet 30 is larger than the area of the positive electrode sheet 10.

[0118] In the present application, the size of the coating 220 on the separator 20 needs to cover the negative electrode. To simplify the process, the coating 220 can completely cover the base film 210 of the separator 20, that is, the area of the coating 220 in the separator 20 can be the same as the area of the base film 210. Further, the area of the separator 20 needs to be larger than the area of the negative electrode sheet 30, and the area of the negative electrode sheet 30 needs to be larger than the area of the positive electrode sheet 10.

[0119] Specifically, in some embodiments, the distance between the edge of the separator 20 and the edge of the negative electrode sheet 30 is 0.5 to 5 mm. In some embodiments, the distance between the edge of the negative electrode sheet 30 and the edge of the positive electrode sheet 10 is 0.5 to 3 mm.

[0120] In the present application, for ease of understanding, it is defined that when the separator 20 is in the unfolded state, its own length direction is X, its own width direction is Y, and its own thickness direction is Z. It can be understood that when the positive electrode sheet 10 and the negative electrode sheet 30 are in the unfolded state, their own length direction, width direction, and thickness direction are the same as those of the separator film.

[0121] The length of the above-mentioned separator 20 is greater than the length of the negative electrode sheet 30. For example, the distance between the length edge of the separator 20 and the length edge of the negative electrode sheet 30 is 0.5 to 5 mm. The length of the above-mentioned negative electrode sheet 30 is greater than the length of the positive electrode sheet 10. For example, the distance between the length edge of the negative electrode sheet 30 and the length edge of the positive electrode sheet 10 is 0.5 to 3 mm.

[0122] Thus, based on the need for the separator 20 to block the short circuit between the positive and negative electrodes, the oxide solid electrolyte can improve the thermal shrinkage performance of the separator 20. Therefore, the coating 220 needs to completely cover the negative electrode. The diffusion of transition metal ions to the negative electrode side will damage the SEI film, while the protein-based binder will hinder the damage to the negative electrode. Therefore, the hindering effect of the protein-based binder is optimal when it completely covers the negative electrode. Therefore, by making the area of the separator 20 larger than the area of the negative electrode sheet 30, and the area of the negative electrode sheet 30 larger than the area of the positive electrode sheet 10, and making the gap within the above range, the damage to the negative electrode can be effectively hindered and the thermal shrinkage performance can be improved.

[0123] In some embodiments, the present application provides a battery, and the battery includes the aforementioned electrode assembly.

[0124] In the battery provided by this application, in the electrode assembly, by utilizing the relatively high lithium-ion conductivity of the solid electrolyte such as oxide solid electrolyte in the coating 220 of the separator 20, the initial internal resistance of the battery can be reduced, ensuring the high-power performance, improving the thermal shrinkage performance of the separator 20, and enhancing the battery safety. By using the protein-based binder in the coating 220 of the separator 20 which contains abundant polar functional groups such as hydroxyl and carboxyl groups, it can complex with transition metal ions to prevent them from diffusing to the negative electrode side and damaging the SEI film, reducing the increase in internal resistance during high-temperature cycling and storage (the coating is preferably arranged near the positive electrode side); in addition, the protein-based binder can swell in the electrolyte to lock the residual electrolyte, further improving the battery safety. The Si-O bond in the silane coupling agent in the coating 220 of the separator 20 can adsorb acidic substances in the electrolyte, reducing the acidity of the electrolyte, while improving the wettability between the protein-based binder, the separator 20, and the oxide solid electrolyte, and enhancing the bonding strength.

[0125] Thus, through the combined use of the protein-based binder, silane coupling agent, and solid electrolyte in the coating of the separator 20, both the internal resistance of the battery is reduced, the high-temperature storage and high-temperature cycling performance are improved, the increase in internal resistance at high temperatures is reduced, and at the same time, the battery safety performance is enhanced, which is beneficial to the application of high specific energy battery systems in the eVTOL field with strong high-power requirements.

[0126] In some embodiments, the battery may further include a packaging structure and an electrolyte, that is, the battery includes a packaging structure, the aforementioned electrode assembly, and an electrolyte. The electrode assembly and the electrolyte are accommodated in the packaging structure. This application does not particularly limit the structure of the electrode assembly, as long as it can achieve the purpose of this application. For example, the structure of the electrode assembly is a laminated structure or a wound structure.

[0127] This application does not particularly limit the packaging structure and the electrolyte, and they can be packaging structures and electrolytes well-known in the art, as long as they can achieve the purpose of this application.

[0128] Optionally, the battery may include any one of a battery cell, a battery module, and a battery pack. Among them, a battery cell refers to a battery including a battery housing and a battery core encapsulated in the battery housing. The shape of the battery cell is not particularly limited, and it can be cylindrical, square, or any other shape.

[0129] Since the battery provided by the embodiments of the present invention adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one.

[0130] In some embodiments, this application provides an electrical device, and the electrical device includes the aforementioned electrode assembly or includes the aforementioned battery.

[0131] The above battery can be used as a power source for an electrical device or as an energy storage unit of the electrical device. Therefore, in the embodiments of the present application, the electrical device has a long standby or endurance time, good stability and high safety.

[0132] Optionally, the electrical device can be but is not limited to being used in mobile phones, tablets, laptop computers, electric toys, electric tools, battery cars, electric vehicles, electric bicycles, electric motorcycles, electric trucks, as well as ships, aircraft, energy storage systems, etc. Among them, the aircraft includes eVTOL.

[0133] Optionally, in some embodiments, the electrical device can be an eVTOL.

[0134] To better understand the present invention, the following will elaborate on the specific implementation process of the present invention in detail with specific implementation manners. The following described embodiments are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those without specific technologies or conditions noted in the embodiments, the technologies or conditions described in the literature in the art or according to the product manual are followed.

[0135] Embodiment 1

[0136] 1. Preparation of the separator, including:

[0137] A coating is formed on one surface of a polyethylene-based film with a thickness of 7 μm, the thickness of the coating is 3 μm, and the total thickness of the separator is 10 μm; the porosity of the base film is 38%, and the porosity of the coating is 55%.

[0138] Among them, the coating contains a binder and a solid electrolyte, and protein-based binder gelatin and vinyltrimethoxysilane are used as the binder, and NASICON-type LATP (Li 1+x Al x Ti 2x (PO4)3) is used as the solid electrolyte. In the coating, the mass ratio of the binder to the solid electrolyte is 10:90, and in the binder, the mass ratio of gelatin to the silane coupling agent is 0.8:1.

[0139] 2. Preparation of the positive electrode sheet, including:

[0140] The positive electrode active material single crystal high-nickel material LiNi 0.90 Co 0.05 Mn 0.05O2, conductive agent conductive carbon black SP, and binder polyvinylidene fluoride (PVDF-5130) are mixed according to a mass ratio of 97.5:1.5:1 to obtain a mixed material. The mixed material is stirred evenly in solvent N-methylpyrrolidone (NMP) to obtain a positive electrode paste. The positive electrode active paste is coated on the current collector aluminum foil, and then through processes such as rolling and cutting, the corresponding positive electrode sheet is obtained.

[0141] 3. Preparation of the negative electrode sheet, including:

[0142] The negative electrode active material high-capacity silicon-carbon material (specific capacity is 650 mAh / g, and the mass ratio of silicon to graphite is 3:7), conductive agent carbon nanotubes, conductive agent conductive carbon (Super C65), and binder polyacrylic acid (PAA) are mixed according to a mass ratio of 96:0.1:1.4:2.5 to obtain a mixed material. The mixed material is stirred evenly in deionized water to obtain a negative electrode paste. The negative electrode paste is coated on the negative electrode current collector copper foil, and after processes such as drying, rolling, and cutting, the negative electrode sheet is obtained.

[0143] 4. Preparation of the electrolyte: Lithium hexafluorophosphate (LiPF6) is dissolved in a mixed solvent composed of ethyl methyl carbonate (EMC) and ethylene carbonate (EC) (the mass ratio of the two is 7:3), and 1% by mass of vinylene carbonate (VC) is added to obtain an electrolyte with a concentration of LiPF6 of 1.15 mol / L.

[0144] 5. Assembly of the electrode assembly and the battery:

[0145] The negative electrode sheet, separator, and positive electrode sheet are stacked in sequence to obtain an electrode assembly, where the coated side of the separator is arranged close to the positive electrode sheet.

[0146] The electrode assembly is placed into a battery case with a capacity of 47 Ah, and through processes such as drying, electrolyte injection (injecting 60 g of electrolyte), encapsulation, formation (high-temperature hot pressing formation, 45 °C), and grading, a lithium-ion battery is obtained.

[0147] Example 2

[0148] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0149] In the preparation of the separator, the material of the base film is polypropylene;

[0150] The protein binder uses gelatin protein.

[0151] The rest are the same as those in Example 1.

[0152] Example 3

[0153] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0154] In the preparation of the separator, the protein binder is soy protein;

[0155] The solid electrolyte is a perovskite-type LLTO (Li 0.5 La 0.5 TiO3) electrolyte.

[0156] The rest are the same as those in Example 1.

[0157] Example 4

[0158] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0159] In the preparation of the separator, the protein binder is gelatin protein;

[0160] The silane coupling agent is vinyltriethoxysilane.

[0161] The rest are the same as those in Example 1.

[0162] Example 5

[0163] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0164] In the preparation of the separator, the thickness of the base film is 9 μm; the thickness of the coating is 3 μm;

[0165] The porosity of the base film is 38%, and the porosity of the coating is 55%.

[0166] The rest are the same as those in Example 1.

[0167] Example 6

[0168] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0169] In the preparation of the separator, the thickness of the base film is 9 μm; the thickness of the coating is 1 μm;

[0170] The porosity of the base film is 45%, and the porosity of the coating is 55%.

[0171] The rest are the same as those in Example 1.

[0172] Example 7

[0173] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0174] In the preparation of the separator, the mass ratio of the binder to the solid electrolyte is 5:95. In the binder, the mass ratio of bone glue to the silane coupling agent is 1:1.

[0175] The rest is the same as that in Example 1.

[0176] Example 8

[0177] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0178] In the preparation of the separator, the mass ratio of the binder to the solid electrolyte is 20:80. In the binder, the mass ratio of bone glue to silane coupling agent is 1:1.

[0179] The rest is the same as that in Example 1.

[0180] Example 9

[0181] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0182] In the preparation of the positive electrode sheet, the positive electrode active material single crystal high-nickel material LiNi 0.90 Co 0.05 Mn 0.05 O2, the conductive agent conductive carbon black and the binder polyvinylidene fluoride are mixed according to the mass ratio of 95:2:3.

[0183] The rest is the same as that in Example 1.

[0184] Comparative Example 1

[0185] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0186] In the preparation of the separator, in the coating, a conventional styrene-butadiene rubber (SBR) binder is used to replace the binder in Example 1, and alumina ceramic is used to replace the solid electrolyte in Example 1.

[0187] The rest is the same as that in Example 1.

[0188] Comparative Example 2

[0189] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0190] In the preparation of the separator, conventional alumina is used to replace the solid electrolyte in Example 1.

[0191] The rest is the same as that in Example 1.

[0192] Comparative Example 3

[0193] The preparation of the battery in this example is basically the same as that in Example 1, except that:

[0194] In the preparation of the separator, a conventional styrene-butadiene rubber (SBR) binder was used to replace the binder in Example 1.

[0195] The rest was the same as in Example 1.

[0196] Comparative Example 4

[0197] The preparation of the battery in this example was basically the same as that in Example 1, except that:

[0198] During the preparation of the battery, the coating on the separator was disposed closer to the negative electrode side.

[0199] The rest was the same as in Example 1.

[0200] Comparative Example 5

[0201] The preparation of the battery in this example was basically the same as that in Example 1, except that:

[0202] In the preparation of the separator, the protein binder was omitted, that is, the binder only included a silane coupling agent.

[0203] The rest was the same as in Example 1.

[0204] It was found during the preparation of Comparative Example 5 that, due to the omission of the protein binder as the binder skeleton and only using a silane coupling agent, the binding performance was basically not available, and thus coating could not be carried out. The separator of Comparative Example 5 was not prepared.

[0205] Performance Test

[0206] The separators prepared by the above examples and comparative examples and the constructed lithium batteries were subjected to performance tests as follows:

[0207] (1) Capacity test of the battery: At room temperature of 25 °C, within the range of 2.5 - 4.25 V, the battery was charged with constant current and constant voltage at 1 / 3 C, the cut-off current was 0.05 C, and then discharged at 1 / 3 C to calculate its capacity Q, Q = I * t, where I was the discharge current and t was the time.

[0208] (2) Energy density test: At room temperature of 25 °C, within the range of 2.5 - 4.25 V, the battery was charged with constant current and constant voltage at 1 / 3 C, the cut-off current was 0.05 C, and then discharged at 1 / 3 C to calculate its energy; the energy density = energy / weight.

[0209] (3) Initial DC internal resistance test of the battery: At room temperature of 25 °C, the SOC of the battery was adjusted to 50%, and it was discharged at a rate of 2 C for 30 s, and its internal resistance value was recorded.

[0210] (4) 45°C High Temperature Cycling Performance Test of the Battery: Within the voltage range of 2.5 - 4.25 V, charge the battery with a constant current of 1C and constant voltage (cut-off current 0.05C), and discharge it with a current of 1C. Calculate the capacity retention rate after 500 cycles. The method for testing the internal resistance after cycling is the same as the initial DC internal resistance testing method at 25°C.

[0211] (5) 55°C High Temperature Storage Performance Test of the Battery: Store the battery at a full charge of 4.25V in an incubator for 180 days. Test its reversible capacity recovery rate and the DC internal resistance after storage, which is the same as the initial DC internal resistance testing method.

[0212] (6) Concentration Test of Mn in the Negative Electrode Sheet: Take the battery after cycling or storage, disassemble it, take the negative electrode sheet, soak it in DMC solvent for 2h, air-dry it, and then scrape off the negative electrode coating (note not to rub off the copper foil). After grinding, use an ICP-OES device to test the concentration of Mn in it.

[0213] (7) Thermal Stability Test of the Battery: Place the battery at a full charge of 4.25V in an oven, heat it up to 130°C at a rate of 5°C / min, and hold for 30 min; continue to heat it up to the specified temperature in 5°C gradients until the battery cell fails, and record the thermal runaway temperature.

[0214] The test results are shown in Table 1 below.

[0215] Table 1 Battery Performance Test Results of Each Example and Comparative Example

[0216]

[0217]

[0218] As can be seen from Table 1, compared with Comparative Examples 1 - 4, the batteries using the separators included in Examples 1 - 9 have reduced internal resistance, improved high temperature (45°C) cycling performance, improved high temperature (55°C) storage performance, and also increased the thermal runaway temperature. A higher thermal runaway temperature means higher safety.

[0219] In Examples 1-9 of the present invention, the separator is a separator with a coating simultaneously coated with a protein-based binder, a silane coupling agent, and an oxide electrolyte, such that the initial internal resistance of the battery including the separator is relatively low, and the increase in internal resistance during cycling and storage is less, the capacity retention rate is higher, and the thermal box failure temperature is higher. Among the separators of Comparative Examples 1-3, for the group with only a protein-based binder and a silane coupling agent, the initial internal resistance is relatively higher. For the group with only an oxide electrolyte, although the initial internal resistance is lower, it cannot reduce the acidity and prevent the dissolution of transition metal ions, resulting in a significant increase in internal resistance during cycling and storage and a lower capacity retention rate. In the separator of Comparative Example 4, on the side of the coated coating facing the negative electrode sheet, the oxide electrolyte reacts, which instead increases the internal resistance and the performance of high-temperature cycling and storage is also worse.

[0220] In addition, it can also be seen from Figure 1 that the functional coating provided by the separator of the present application can not only reduce the internal resistance of the battery, but also prevent the shuttle of transition metal ions between the positive and negative electrodes, improving the high-temperature cycling performance and storage performance.

[0221] Figure 2 shows the schematic diagram of the complexation of transition metal ions by the protein-based binder, Figure 2 in which the amino acids in the protein-based binder (Sericin represents sericin) act as electron donors, and the transition metal (M is a transition metal) acts as an electron acceptor, and the two undergo a complexation reaction to form the complex shown in the figure. Thus, through the polypeptide functional groups on the surface, transition metal ions can be chelated to prevent their diffusion to the negative electrode.

[0222] Figure 3 shows the schematic diagram of the silane coupling agent improving the wetting effect. Figure 3 In it, the silicon functional group of the silane coupling agent is linked to the protein-based binder (Sericin represents sericin), and the carbon functional group and the oxide solid electrolyte (such as lithium aluminum titanium phosphate LATP) are linked by hydrogen bonds to improve the linking effect between the protein-based binder and the inorganic substance.

[0223] The parts not detailed in the present invention are well-known technologies to those skilled in the art.

[0224] The basic principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present invention. In addition, the above-disclosed specific details are only for the purpose of illustration and easy understanding, rather than limitations, and the above details do not limit the present invention to necessarily adopt the above specific details to implement.

[0225] It should be noted that the term "and / or" or " / " used in this text is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. The singular forms of "a", "the", and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0226] In the specific embodiments and the claims, a list of items connected by the terms "at least one of", "at least one in", "at least one kind in", or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0227] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode assembly, characterized in that: It includes a positive electrode sheet, a negative electrode sheet and a separator arranged between the positive electrode sheet and the negative electrode sheet; The positive electrode sheet includes a positive electrode active material, and the positive electrode active material includes an oxide containing transition metal ions; The diaphragm includes a base film and a coating disposed on at least one side of the base film, the coating includes a solid electrolyte and a binder, the binder includes a protein binder having a functional group, and the functional group includes at least one of a hydroxyl group, a carboxyl group, an amine group or an amide group; The coating layer located on one side close to the positive electrode sheet also contains a complex of the functional group and the transition metal ion.

2. The electrode assembly according to claim 1, characterized in that: The amino acid content of the protein binder is ≥ 70%; and / or, The relative molecular weight of the protein binder is 3 to 300 kDa; and / or, The protein binder includes at least one of bone glue, gelatin, soybean glue or sericin.

3. The electrode assembly according to claim 1, characterized in that: The transition metal ion includes at least one of nickel ion, cobalt ion, manganese ion, copper ion, zirconium ion, titanium ion, iron ion or tungsten ion; Preferably, the chemical formula of the positive electrode active material is LiNi x Co y M 1-x-y O2, wherein M includes at least one of Mn, Al, Mg, Zr, Ti, Cu, Fe, W or B, 0.7≤x≤1.0, 0≤y≤0.

3.

4. The electrode assembly according to claim 1, characterized in that: The solid electrolyte comprises an oxide solid electrolyte; Preferably, the solid electrolyte includes at least one of a NASCION solid electrolyte, a LISCION solid electrolyte, a garnet solid electrolyte or a perovskite solid electrolyte; Preferably, the ionic conductivity of the solid electrolyte is 10 -3 ~10 -5 S / cm; Preferably, the average particle size of the solid electrolyte is 500nm to 1500nm; Preferably, the mass ratio of the solid electrolyte to the binder is (80-95):(5-20).

5. The electrode assembly according to claim 1, characterized in that: The adhesive further comprises a silane coupling agent; Preferably, the silane coupling agent includes at least one of vinyl silane, amino silane, epoxy silane, mercapto silane or methacryloxy silane; Preferably, the mass ratio of the protein binder to the silane coupling agent is (0.5-2):

1.

6. The electrode assembly according to claim 1, characterized in that: The base film comprises at least one of polyethylene, polypropylene, polyethylene terephthalate, non-woven fabric or aramid; Preferably, the porosity of the base film is 35% to 55%; Preferably, the porosity of the coating is 50% to 70%; Preferably, the thickness of the base film is 2 μm to 18 μm; Preferably, the pore size of the base membrane ranges from 20 nm to 60 nm.

7. The electrode assembly according to claim 1, characterized in that: The coating has a thickness of 1 μm to 5 μm; and / or, The ratio of the thickness of the coating to the thickness of the base film is 0.05 to 0.5; and / or, The thickness of the separator is 5 μm to 20 μm.

8. The electrode assembly according to any one of claims 1 to 7, characterized in that: The area of ​​the separator is larger than the area of ​​the negative electrode sheet, and the area of ​​the negative electrode sheet is larger than the area of ​​the positive electrode sheet; Preferably, the distance between the edge of the separator and the edge of the negative electrode sheet is 0.5 to 5 mm; Preferably, the distance between the edge of the negative electrode sheet and the edge of the positive electrode sheet is 0.5 to 3 mm.

9. A battery, characterized in that: The battery comprises the electrode assembly according to any one of claims 1 to 8.

10. An electrical device, characterized in that: The electrical device comprises the electrode assembly according to any one of claims 1 to 8, or comprises the battery according to claim 9.

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