Organic-inorganic hybrid composite and coating composition, separator, secondary battery, battery module, battery pack and electrical device containing the same

Abstract

The present application provides an organic-inorganic hybrid composite that can be applied to a separator coating for a secondary battery. The organic-inorganic hybrid composite is composed of basic units represented by formula (I) periodically assembled along at least one spatial direction: [L x‑i N i ][M a C b ]·A z (I) wherein the defect percentage represented by i / x*100% is 1% to 30%; the present application also provides a coating composition comprising the coating composition, a coating formed by the coating composition, a secondary battery separator comprising the coating, and a secondary battery, battery module, battery pack, and device comprising the separator. By applying the organic-inorganic hybrid composite of the present application to the coating, the electrolyte wettability of the secondary battery separator is improved, and the electrolyte retention rate is increased, thereby improving the rate performance and cycle life of the secondary battery.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to PCT patent application PCT / CN2021 / 103405, filed on June 30, 2021, entitled “Organic-inorganic hybrid composites and coating compositions, diaphragms, secondary batteries, battery modules, battery packs and electrical devices comprising the same,” and the entire contents of that application are incorporated herein by reference. Technical Field

[0003] The present application relates to the technical field of secondary batteries, and in particular to an organic-inorganic hybrid composite that can be used to form a coating for a secondary battery separator, a coating composition comprising the composite, a coating formed from the coating composition, a secondary battery separator comprising the coating, and a secondary battery, battery module, battery pack, and electrical device comprising the separator. Background Art

[0004] Lithium-ion secondary batteries are widely used in many consumer electronic products due to their high energy density, long cycle life, and lack of memory effect. In recent years, with the continuous development of electric vehicles and energy storage systems, the energy density requirements of lithium-ion secondary batteries have also been continuously increasing.

[0005] A secondary battery is a battery that can be recharged to activate the active materials after the battery is discharged and continue to be used. Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte and a solvent. During the charge and discharge process of the battery, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. A separator is provided between the positive electrode sheet and the negative electrode sheet. The separator is an important component of the lithium-ion battery and is usually a polymer functional material with nano-scale micropores. The main function of the separator is to prevent the two electrodes from contacting and short-circuiting while allowing electrolyte ions to pass through. Specifically, the separator can insulate electrons to prevent internal short circuits, while allowing active ions to pass through and move between the positive and negative electrodes. The performance of the separator determines the interface structure, internal resistance, etc. of the battery, which directly affects the capacity, cycle and safety performance of the battery.

[0006] Currently, commercial lithium-ion battery separators are mostly made of polyolefin materials, particularly polyolefin microporous membranes, including polyethylene (PE) monolayer membranes, polypropylene (PP) monolayer membranes, and PP / PE / PP multilayer microporous membranes, which are composites of PP and PE. These polyolefin microporous membranes often have poor electrolyte wettability, making electrolyte injection difficult during production and increasing polarization, which reduces the battery's power density and cycle life.

[0007] In the prior art, ionic conductive coatings such as ceramic coatings have been used to improve wettability. However, the manufacture of these coatings requires calcination, and the process is cumbersome and complex. Especially, the effect on improving wettability is limited, resulting in insufficient improvement in the rate performance and cycle life of the battery. In addition, high-temperature resistant metal-organic framework materials (MOFs) have also been used as the main coating materials to improve wettability. However, when using MOF material coatings to improve the wettability of the separator, this improvement only depends on the increase in the porosity of the separator, that is, the increase in specific surface area. In fact, the contribution from the material itself is very small. Therefore, the wettability of the MOF material-coated separator still needs to be improved. Summary of the Invention

[0008] In view of the above problems existing in the background art, the purpose of the present application is to provide a coating material for a secondary battery separator, which has the effect of improving the wettability of the electrolyte, and at the same time can also improve the electrolyte retention rate, thereby reducing polarization, improving the power density of the secondary battery, and increasing the cycle life.

[0009] To achieve the above object, on the one hand, the present application provides an organic-inorganic hybrid composite, which is composed of basic units represented by the following formula (I) periodically assembled along at least one spatial direction.

[0010] [L z N i [M a C b ·A z (I)

[0011] Wherein, in formula (I), M represents a first transition series metal element, C represents an atom, atomic group, or anion that can optionally form a metal cluster with M, L represents an organic ligand that can form a coordination bond with metal M or metal cluster M a C b formed coordination bond, especially an organic bridging ligand, N represents a ligand defect, and A represents an atom or cation that can be embedded and removed. x can take a value from 1 to 4, more preferably can take a value from 1 to 3, a can take a value greater than 0 and less than or equal to 4, more preferably can take a value from 1 to 4. z can take a value from 0 to 2, more preferably can take a value from 0 to 1. In formula (I), the following relationship can be satisfied: 0 < i < x, and 0 ≤ b:a ≤ 1.

[0012] In the present application, the defect percentage i / x * 100% is used to represent the defect degree of the organic-inorganic hybrid composite of the present application relative to an ideal defect-free crystal structure. The defect percentage can be about 1% to about 30%. <In one embodiment, the defect percentage may be from about 2% to about 20%. In one embodiment, the defect percentage may be from about 2.5% to about 18%. In one embodiment, the defect percentage may be from about 5% to about 10%.

[0014] In one embodiment, in formula (I), the following relationship may be satisfied: 1 / 2≤x:a≤3.

[0015] In one embodiment, in formula (I), the ratio between a and b may satisfy 1 / 4≤b:a≤1.

[0016] In one embodiment, M may be selected from one or more of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn. More preferably, M may be selected from one or more of Mn, Fe, Co, Cu, and Zn.

[0017] In one embodiment, C can be selected from -O-, =O, O 2- 、S 2- 、F - , Cl - Br - , I - , CO, -OH and OH - More optionally, C can be -O- or -OH.

[0018] In one embodiment, the organic bridging ligand L can be selected from at least one of cyano, benzimidazole ligands, porphyrin ligands, pyridine ligands, pyrazole ligands, pyrimidine ligands, piperidine ligands, pyrrolidine ligands, furan ligands, thiophene ligands, pyrazine ligands, piperazine ligands, pyridazine ligands, triazine ligands, tetrazine ligands, indole ligands, quinoline ligands, carbazole ligands, morpholine ligands, carbazole ligands and polycarboxylic acid ligands. One or more hydrogen atoms in the organic bridging ligand L may be optionally substituted with one or more substituents, each of which may be independently selected from at least one of a cyano group, a nitro group, an amino group, an aldehyde group, a carboxyl group, a halogen group, a C1-C6 alkyl group, a C1-C6 hydroxyalkyl group, a C1-C6 alkoxy group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, a C3-C8 cycloalkyl group, a C6-C10 aryl group, a C6-C10 heteroaryl group, and any combination thereof. In one embodiment, the organic bridging ligand L may be selected from at least one of a cyano group, a benzimidazole ligand, and a polycarboxylic acid ligand. In one embodiment, the organic bridging ligand L may be selected from at least one of a cyano group, a benzimidazole ligand, a trimesic acid ligand, and a terephthalic acid ligand. In one embodiment, the organic bridging ligand L may be selected from at least one of a cyano group, a 5-chlorobenzimidazole ligand (cbIm), a trimesic acid ligand (BTC), a terephthalic acid ligand (BDC), and a tris(2-benzimidazolemethyl)amine ligand (NTB).

[0019] In one embodiment, A may be an atom or cation of one or more metal elements selected from Li, Na, K, Rb, Cs, Sr, Zn, Mg, and Ca. More preferably, A may be Li or Na.

[0020] In one embodiment, in the organic-inorganic hybrid composite of the present application, the basic unit represented by formula (I) can be periodically assembled along at least one of the three spatial directions X', Y' and Z', and the three directions X', Y' and Z' respectively form an angle of 0 to 75 degrees with the X direction, Y direction and Z direction of the Cartesian coordinate system, and optionally an angle of 5 to 60 degrees.

[0021] In one embodiment, the basic units represented by formula (I) may be periodically assembled along at least one spatial direction of the X direction, the Y direction, and the Z direction of a Cartesian coordinate system.

[0022] In one embodiment, in the organic-inorganic hybrid composite of the present application, the number of the basic units represented by formula (I) periodically assembled along at least one spatial direction may be about 3 to about 10,000.

[0023] On the other hand, the present application also provides a coating composition for a secondary battery separator, which may include the organic-inorganic hybrid composite of the present application as described above.

[0024] In one embodiment, in the coating composition of the present application, the content of the organic-inorganic hybrid composite may be from about 12 wt % to about 90 wt % based on the total weight of the coating composition. In one embodiment, the content of the organic-inorganic hybrid composite may be from about 17 wt % to about 85 wt % based on the total weight of the coating composition. In one embodiment, the content of the organic-inorganic hybrid composite may be from about 34 wt % to about 68 wt % based on the total weight of the coating composition.

[0025] In one embodiment, optionally, the coating composition of the present application may further include inorganic particles.

[0026] In one embodiment, when inorganic particles are included in the coating composition of the present application, the organic-inorganic hybrid composite may account for about 15 wt % to about 85 wt % based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating. In one embodiment, the organic-inorganic hybrid composite may account for about 20 wt % to about 80 wt % based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating. In one embodiment, the organic-inorganic hybrid composite may account for about 40 wt % to about 80 wt % based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating.

[0027] In one embodiment, when inorganic particles are included in the coating composition of the present application, the inorganic particles can be selected from boehmite, zeolite, molecular sieve, alumina, aluminum oxyhydroxide, silica, aluminum nitride, silicon carbide, magnesium oxide, calcium oxide, zinc oxide, zirconium oxide, titanium oxide, and mixtures thereof.

[0028] On the other hand, the present application also provides a secondary battery separator. The secondary battery separator of the present application may include a polymer substrate layer and a coating layer coated on the substrate layer, wherein the coating layer may include the organic-inorganic hybrid composite of the present application as described above or the coating composition of the present application as described above.

[0029] In another aspect, the present application further provides a secondary battery, which may include a positive electrode, a negative electrode, an electrolyte, and the separator for the secondary battery of the present application as described above.

[0030] On the other hand, the present application further provides a battery module. The battery module of the present application may include the secondary battery of the present application as described above.

[0031] On the other hand, the present application further provides a battery pack. The battery pack of the present application may include the battery module of the present application as described above.

[0032] On the other hand, the present application further provides an electric device, which may include the secondary battery of the present application, the battery module of the present application, the battery pack of the present application, or a combination thereof.

[0033] In the secondary battery of the present application, by applying the organic-inorganic hybrid composite of the present application in the coating of the diaphragm, the electrolyte wettability of the diaphragm is significantly improved, and the electrolyte retention rate is greatly improved, thereby reducing polarization, ultimately leading to a significant improvement in the power density and cycle life of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of a secondary battery according to one embodiment of the present application.

[0035] Figure 2 yes Figure 1 FIG. 1 is an exploded view of a secondary battery according to an embodiment of the present application.

[0036] Figure 3 Schematic diagram of a battery module according to one embodiment of the present application.

[0037] Figure 4 Schematic diagram of a battery pack according to one embodiment of the present application.

[0038] Figure 5 yes Figure 4 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0039] Figure 6 FIG. 1 is a schematic diagram of a device using a secondary battery as a power source according to an embodiment of the present application.

[0040] Figure 7 is a SEM photograph of the material obtained in Preparation Example 1.

[0041] Figure 8 This is a SEM photograph of the separator with the coating layer obtained in Example 1.

[0042] Figure 9a 、 9b 9c and 9d are wettability test photos of the diaphragms of Control Example 1, Comparative Example 1 and Example 1 obtained in Test Example 1, respectively.

[0043] Figure 10 It is a cycle performance curve diagram of the battery cells of Control Application Example 1, Comparative Application Example 1 and Application Example 1 obtained in Test Example 5.

[0044] Description of reference numerals:

[0045] 1 battery pack

[0046] 2 upper box

[0047] 3 lower cabinets

[0048] 4 battery modules

[0049] 5 Secondary batteries

[0050] 51 shell

[0051] 52 electrode assembly

[0052] 53 top cover assembly DETAILED DESCRIPTION

[0053] To make the purpose, technical solutions and advantages of this application more clear, the following will describe the embodiments of the application in detail with reference to the accompanying drawings. However, those skilled in the art should understand that these embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of the present invention.

[0054] For the sake of clarity, this application specifically discloses certain numerical ranges. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value may itself serve as a lower limit or upper limit and be combined with any other point or single value, or with other lower limits or upper limits, to form an unspecified range.

[0055] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0056] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0057] Unless otherwise specified, all steps of the present 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 may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0058] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0059] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0060] In one aspect, the present application provides an organic-inorganic hybrid composite. The organic-inorganic hybrid composite of the present application can be composed of basic units represented by the following formula (I) periodically assembled along at least one spatial direction.

[0061] [L x-i N i ][M a C b ]·A z (I)

[0062] In formula (I), M can represent a first transition metal element. The first transition metal element has active chemical properties, a stable low oxidation state (+1 to +4), a large electronegativity, and a strong coordination ability. This is conducive to the formation of coordination bonds between the first transition metal element and an organic ligand (also referred to as an organic ligand), or forming a metal cluster and then forming a coordination bond with a common organic ligand, avoiding the high element valence state of +5 to +7, which in turn leads to excessive coordination bonds required in the space near the metal atom. Moreover, the smaller steric hindrance effect of the first transition metal element makes it easier to form a stable coordination structure, and unlike the second and third transition metal elements, it is easier to form metal-metal bonding, thereby affecting the stability of the coordination bond.

[0063] Alternatively, M may be selected from one or more of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn. More preferably, M may be selected from one or more of Mn, Fe, Co, Cu and Zn.

[0064] In formula (I), C represents an atom, an atomic group, or an anion that can optionally form a metal cluster with M. Alternatively, C can be selected from -O-, =O, O 2- 、S 2- 、F - , Cl - Br - , I - , CO, -OH and OH- More optionally, C can be -O- or -OH.

[0065] In formula (I), L represents a metal M or a metal cluster M a C b Organic ligands that form coordination bonds, particularly organic bridging ligands. While the mechanism is not fully understood, it is speculated that, compared to monodentate ligands (i.e., ligands containing a single coordinating atom), organic bridging ligands can effectively provide the complete metal-ligand framework required to accommodate a certain proportion of defect sites. This complete framework structure can fully achieve the effect of improving the wettability of the coating membrane while maintaining the structural stability of the organic-inorganic hybrid complex.

[0066] As non-limiting examples, the organic bridging ligand L may include cyano (CN), benzimidazole ligands, porphyrin ligands, pyridine ligands, pyrazole ligands, pyrimidine ligands, piperidine ligands, pyrrolidine ligands, furan ligands, thiophene ligands, pyrazine ligands, piperazine ligands, pyridazine ligands, triazine ligands, tetrazine ligands, indole ligands, quinoline ligands, carbazole ligands, morpholine ligands, carbazole ligands and polycarboxylic acid ligands. One or more hydrogen atoms in the organic bridging ligand L are optionally substituted by one or more substituents, and the substituents can be independently selected from cyano, nitro, amino, aldehyde, carboxyl, halogen, C1-C6 alkyl, C1-C6 hydroxyalkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, C3-C8 cycloalkyl, C6-C10 aryl, C6-C10 heteroaryl and any combination thereof.

[0067] As non-limiting examples, benzimidazole ligands may include benzimidazole ligands (bIm), 5-chlorobenzimidazole ligands (cbIm), 5-nitrobenzimidazole ligands (nbIm), 2-methyl-5-chlorobenzimidazole ligands, tris(2-benzimidazolemethyl)amine ligands (NTB), etc. Imidazole ligands may include imidazole ligands (IM), 2-methylimidazole ligands (mIM), 2-nitroimidazole ligands (nIM), etc. Pyrimidine ligands may include 2-hydroxy-5-fluoropyrimidine ligands (F-pymo). Triazine ligands may include 2,4,6-trimercapto-s-triazine ligands (TATB). Tetrazine ligands may include 3,6-di-4-pyridyl-1,2,4,5-tetrazine ligands (DPT). The polycarboxylic acid ligands may include pyromellitic acid ligand (BTEC), trimesic acid ligand (BTC), terephthalic acid ligand (BDC), 2,6-naphthalene dicarboxylic acid ligand (NDC), 1,4-phenylenedicarboxylic acid ligand (PDA), 2,3-pyrazine dicarboxylic acid ligand (PZDC), 2,2-bis(4-carboxyphenyl)hexafluoropropane ligand (H2hfipbb), 1,4,5,8-naphthalene tetracarboxylic acid ligand (NTC), 5-tert-butyl-1, 3-Benzenedicarboxylic acid ligand (TPIC), biphenyltetracarboxylic acid ligand (BPTC), 9,10-anthracenedicarboxylic acid ligand (ADC), 4-aminophenyltetrazolyl acid ligand (APT), 2,4,6-pyridinetricarboxylic acid ligand (PYTA), 4,4',4"-benzene-1,3,5-triyl-tris-benzoic acid ligand (BTB), pyridinedicarboxylic acid ligand (PDC), 2,3-pyrazine-tetrazolyl acid ligand (DTP), glutaric acid ligand (GLA), etc.

[0068] In one embodiment, the organic bridging ligand L can be selected from cyano, benzimidazole ligands and polycarboxylic acid ligands. In one embodiment, the organic bridging ligand L can be selected from cyano, benzimidazole ligands, trimesic acid ligands and terephthalic acid ligands. In one embodiment, the organic bridging ligand L can be selected from cyano, 5-chlorobenzimidazole ligand (cbIm), trimesic acid ligand (BTC), terephthalic acid ligand (BDC) and tris (2-benzimidazolemethyl) amine ligand (NTB).

[0069] Among them, in the present application, these polycarboxylic acid ligands coordinate with the central atom metal, can remove at least one hydrogen, and may play the role of a Lewis base in the complex.

[0070] In formula (I), N represents a ligand defect (i.e., a lattice vacancy). In the organic-inorganic hybrid composite of the present application, the defect is caused only by ligand detachment or by the simultaneous detachment of the ligand and one or several metal or metal cluster atoms connected thereto. Although the mechanism is not fully clear, it is speculated that in the organic-inorganic hybrid composite of the present application, the defects existing in the periodically assembled three-dimensional structure can provide exposed sites for organic ligands, and all organic ligands have polar groups, and the polar groups can form intermolecular hydrogen bonds with the solvent molecules of the electrolyte. Therefore, when the organic-inorganic hybrid composite of the present application is applied to the coating of the separator, the electrolyte wettability of the coated separator can be improved. Moreover, since the ligand defects are uniformly distributed in the organic-inorganic hybrid composite structure, the organic-inorganic hybrid composite of the present application can more effectively improve the electrolyte wettability of the separator, while increasing the electrolyte retention rate, so as to reduce the polarization inside the battery cell, improve the battery power density, and increase the cycle life.

[0071] In formula (I), A represents an atom or cation that can be inserted and extracted. Optionally, A can be selected from atoms or cations of one or more metal elements such as Li, Na, K, Rb, Cs, Sr, Zn, Mg, and Ca. More optionally, A represents Li or Na.

[0072] In formula (I), the value of each of x, i, z, a, and b is not limited. In one embodiment, x can take a value from 1 to 4. More optionally, x can take a value from 1 to 3. In one embodiment, a can take a value greater than 0 and less than or equal to 4. More optionally, a can take a value from 1 to 4. In one embodiment, b can take a value greater than or equal to 0 and less than or equal to 4. More optionally, b can take a value from 1 to 4. In one embodiment, z can take a value from 0 to 2. More optionally, z can take a value from 0 to 1.

[0073] In formula (I), the following relationship can be satisfied: 0 < i < x. In the corresponding defect-free organic-inorganic hybrid composite, i = 0. The corresponding chemical formula is L x [M a C b ·A z .

[0074] In the present application, the value of i in formula (I) can be determined by the following method. Specifically, a known method, such as X-ray diffraction analysis (XRD), in-situ cold field emission gun double aberration corrected transmission electron microscopy (STEM), etc., can be used to determine the theoretical formula L of the defect-free product corresponding to the organic-inorganic hybrid composite of the present application x [M a C b ·Az The above theoretical formula may also be known to those skilled in the art. In addition, based on the measured element ratios of the organic-inorganic hybrid composite, the empirical formula of the basic unit in the composite can be obtained: x’ [M a C b ]·A z The above element ratios can be determined by measurement methods known in the art, such as inductively coupled plasma emission spectroscopy (ICP), carbon and sulfur element analyzer, elemental quantitative analysis (EA), etc. Finally, the empirical formula L x’ [M a C b ]·A z The theoretical formula L corresponding to the product without defects x [M a C b ]·A z By comparing the values ​​of i, we can determine the defect percentage i / x*100%, which represents the degree of defects in the organic-inorganic hybrid composite of the present application relative to an ideal defect-free crystal structure. Specifically, defect percentage = (x-x') / x*100%.

[0075] For the purpose of illustration only, the determination of the theoretical formula of the corresponding defect-free product is described in more detail. In theory, when all metal elements and ligand types are clear, the element ratio in the organic-inorganic hybrid complex will only depend on the valence of the metal element that occupies an absolute dominant proportion in the complex, and the coordination number of the corresponding ligand. For example, if there is only one M as a metal element in the organic-inorganic hybrid complex, as determined by X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), etc., the valence of the M that occupies an absolute dominant proportion is +a1, and the coordination number of the ligand L is a2. In the case of no metal cluster formation, the theoretical chemical formula of the organic-inorganic hybrid complex can be L a1 M a2 If there is an atom or cation A in the organic-inorganic hybrid complex that does not participate in the molecular framework, that is, can be embedded and extracted, and the valence of A is +a3, in the case of no metal cluster formation, the theoretical chemical formula of the organic-inorganic hybrid complex can be L a1 M a2-a3 / a1*z ·A z In the case of forming metal clusters, for example, the existence form of the metal clusters can be examined by means of in-situ cold field emission gun double spherical aberration corrected transmission electron microscopy (STEM) or other characterization means capable of analyzing the molecular structure, and then the valence of the metal clusters is substituted for balancing. Finally, the theoretical formula L of the defect-free product corresponding to the organic-inorganic hybrid composite of the present application can be determined. x[M a C b ]·A z , where the subscript numbers a and b can be rounded to integers as needed.

[0076] In the organic-inorganic hybrid composite of the present application, the defect percentage may be from about 1% to about 30%. The defect percentage may be not less than about 2%, more preferably not less than 3, more preferably not less than about 4%, more preferably not less than about 5%, more preferably not less than about 6%, more preferably not less than about 7%, more preferably not less than about 8%. In addition, the defect percentage may be not more than about 27.5%, more preferably not more than about 25%, more preferably not more than about 22.5%, more preferably not more than 20%, more preferably not more than about 17.5%, more preferably not more than about 15%, more preferably not more than about 12.5%, more preferably not more than about 10%. In one embodiment, the defect percentage may be from about 2% to about 20%. In one embodiment, the defect percentage may be from about 5% to about 10%.

[0077] In formula (I), the following relationship may be satisfied: 1 / 2 ≤ x:a ≤ 3. For clarity, x:a represents the ratio of ligands and defects to metal atoms. When M is cations of two or more metal elements, a represents the number of all metal cations in a single unit of formula I.

[0078] In formula (I), the following relationship may be satisfied: 0≤b:a≤1. a C b In this case, the ratio between a and b can satisfy 1 / 4≤b:a≤1.

[0079] In the organic-inorganic hybrid composite of the present application, by applying the defect percentage within the range as described above, it is possible to provide sufficient ligand defect sites (i.e., ligand exposure sites) for the organic-inorganic hybrid composite. Although the mechanism is not yet fully clear, it is speculated that when the organic-inorganic hybrid composite of the present application is applied to the coating of the secondary battery diaphragm, the organic ligand polar groups and the solvent molecules of the secondary battery electrolyte fully form intermolecular hydrogen bonds, thereby ensuring that the electrolyte wettability of the diaphragm is fully improved to meet the requirements of reducing polarization; at the same time, the three-dimensional structural stability of the organic-inorganic hybrid composite in the diaphragm coating is maintained, and it will not collapse during the charge and discharge process of the secondary battery cell. In addition, by applying the defect percentage within the range as described above, the occurrence of side reactions in the secondary battery can also be suppressed, thereby improving the cycle life of the battery cell.

[0080] In the present application, optionally, the formation of defects can be formed by adding an appropriate amount of defect-introducing substances during the preparation process of the organic-inorganic hybrid composite. As a non-limiting example, the substance introducing defects can be an acidic substance, an alkaline substance, a redox agent or a chelating agent, etc. For example, in the process of synthesizing the organic-inorganic hybrid composite by liquid phase coprecipitation, in the process of adding a solution of a salt containing metal M to a solution of an acid, anhydride or a salt containing a corresponding ligand, an appropriate amount of other kinds of acid is added, thereby introducing defects in the organic-inorganic hybrid composite produced. By changing the amount of the substance or other raw materials added to introduce defects, the defect percentage of the prepared organic-inorganic hybrid composite can be adjusted so that the defect percentage falls within the scope specified in the present application, thereby fully improving the electrolyte wettability of the secondary battery separator, improving the electrolyte retention rate, reducing polarization, and improving the power density and cycle life of the battery.

[0081] In the organic-inorganic hybrid composite of the present application, the basic unit represented by formula (I) can be periodically assembled along at least one of the three spatial directions X', Y' and Z', and the three directions X', Y' and Z' are respectively at an angle of 0 to 75 degrees with the X direction, Y direction and Z direction of the Cartesian coordinate system, and an angle of 5 to 60 degrees is optional. In one embodiment, the basic unit represented by formula (I) can be periodically assembled along at least one spatial direction of the X direction, Y direction and Z direction of the Cartesian coordinate system.

[0082] In the organic-inorganic hybrid composite of the present application, the number of the basic units represented by formula (I) periodically assembled along at least one spatial direction may be about 3 to about 10,000.

[0083] On the other hand, the present application also provides a coating composition for a secondary battery separator, which may include the organic-inorganic hybrid composite of the present application as described above.

[0084] The coating composition of the present application can be prepared by mixing the organic-inorganic hybrid composite of the present application with a binder in an appropriate manner.

[0085] In the coating composition of the present application, based on the total weight of the coating composition, the content of the organic-inorganic hybrid type composite can be from about 12wt% to about 90wt%. Based on the total weight of the coating composition, the content of the organic-inorganic hybrid type composite can be selected to be not less than about 17wt%, more preferably not less than about 24wt%, more preferably not less than about 27wt%, more preferably not less than about 34wt%. Moreover, based on the total weight of the coating composition, the content of the organic-inorganic hybrid type composite can be selected to be not more than about 90wt%, more preferably not more than about 85wt%, more preferably not more than about 80wt%, more preferably not more than about 75wt%, more preferably not more than about 68wt%. In one embodiment, based on the total weight of the coating composition, the content of the organic-inorganic hybrid type composite can be from about 17wt% to about 85wt%. In one embodiment, based on the total weight of the coating composition, the content of the organic-inorganic hybrid type composite can be from about 34wt% to about 68wt%.

[0086] Optionally, the coating composition of the present application may further include inorganic particles. For example, the inorganic particles may be selected from boehmite, zeolite, molecular sieve, aluminum oxide, aluminum oxyhydroxide, silicon dioxide, aluminum nitride, silicon carbide, magnesium oxide, calcium oxide, zinc oxide, zirconium oxide, titanium oxide, and mixtures thereof. In this case, the organic-inorganic hybrid composite and the inorganic particles can be more tightly combined due to the complementary nature of the particle morphology; the organic-inorganic hybrid composite plays a role in improving wettability, increasing electrolyte retention, and increasing the cell injection rate, while the inorganic particles can provide a rigid and stable diaphragm structure, and the two play a synergistic role.

[0087] In the case of inorganic particles included in the coating composition of the present application, the organic-inorganic hybrid composite mass ratio may be from about 15 wt % to about 85 wt % based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating. Based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating, the organic-inorganic hybrid composite mass ratio may be no less than about 20 wt %, more preferably no less than about 35 wt %, more preferably no less than about 40 wt %, more preferably about 55 wt %. Moreover, based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating, the organic-inorganic hybrid composite mass ratio may be no more than about 80 wt %, optionally no more than about 75 wt %, more preferably no more than about 65 wt %, more preferably no more than about 60 wt %. In one embodiment, based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating, the organic-inorganic hybrid composite mass ratio may be from about 20 wt % to about 80 wt %. In one embodiment, the organic-inorganic hybrid composite may account for about 40 wt % to about 80 wt % based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating. In one embodiment, the organic-inorganic hybrid composite may account for about 40 wt % to about 60 wt % based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating.

[0088] Optionally, the coating composition of the present application may further include one or more additives, for example, one or more components selected from binders, stabilizers, wetting agents, defoaming agents, rheology modifiers, and pH adjusters.

[0089] As non-limiting examples, the binder in the coating composition can be acrylic acid, methyl acrylate, acrylic acid-acrylate-acrylonitrile copolymer, or mixtures thereof.

[0090] As non-limiting examples, the stabilizer in the coating composition can be methylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, or mixtures thereof.

[0091] As non-limiting examples, the wetting agent in the coating composition can be a polyoxyethylene ether, a polyether silicone copolymer, a polyoxyethylene alkanolamide, or a mixture thereof.

[0092] As non-limiting examples, the defoaming agent in the coating composition can be polyoxypropylene glycerol ether, polyoxyethylene oxypropylene glycerol ether, polydimethylsiloxane, or a mixture thereof.

[0093] As non-limiting examples, the rheology modifier in the coating composition may be ethanol, propylene glycol, and glycerol, or mixtures thereof.

[0094] As non-limiting examples, the pH adjuster in the coating composition can be hydrochloric acid, sodium hydroxide, lithium hydroxide, sodium phosphate, sodium dihydrogen phosphate, lithium phosphate, lithium dihydrogen phosphate, or mixtures thereof.

[0095] In another aspect, the present application further provides a secondary battery separator. The secondary battery separator of the present application may include a polymer substrate layer and a coating layer coated on the substrate layer, wherein the coating layer may include the organic-inorganic hybrid composite of the present application as described above or the coating composition of the present application as described above.

[0096] The present application also provides a secondary battery, which includes a positive electrode, a negative electrode, an electrolyte, and the secondary battery separator of the present application as described above.

[0097] The present application also provides a battery module, which includes the secondary battery of the present application as described above.

[0098] The present application also provides a battery pack, which includes the battery module of the present application as described above.

[0099] The present application also provides an electrical device, which includes the secondary battery of the present application as described above, or the battery module of the present application as described above, or the battery pack of the present application as described above, or a combination thereof.

[0100] In the secondary battery of the present application, by applying the organic-inorganic hybrid composite of the present application in the coating of the diaphragm, the electrolyte wettability of the diaphragm is significantly improved, and the electrolyte retention rate is greatly improved, thereby reducing polarization, ultimately leading to a significant improvement in the power density and cycle life of the secondary battery.

[0101] The secondary battery, battery module, battery pack, and device of the present application will be described below with reference to the accompanying drawings as appropriate.

[0102] In one embodiment of the present application, a secondary battery is provided.

[0103] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0104] [Positive electrode]

[0105] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material. The positive electrode active material includes, but is not limited to, lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel manganese aluminum oxide, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium iron silicate, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel lithium manganese oxide, spinel lithium nickel manganese oxide, lithium titanate, etc. The positive electrode active material can use one or more of these.

[0106] As an example, the positive electrode current collector has two surfaces opposite to 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 electrode current collector.

[0107] In the secondary battery of the present application, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0108] The positive electrode film layer may also optionally include a conductive agent. However, the type of conductive agent is not specifically limited and can be selected by those skilled in the art based on actual needs. For example, the conductive agent used in the positive electrode film layer may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0109] In the present application, the positive electrode sheet can be prepared according to methods known in the art. As an example, the positive electrode active material, conductive agent, and binder of the present application can be dispersed in a solvent (e.g., N-methylpyrrolidone (NMP)) to form a uniform positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing, and other processes, the positive electrode sheet is obtained.

[0110] [Negative electrode]

[0111] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0112] In the secondary battery of the present application, the negative electrode active material can use the negative electrode active material commonly used in the art for preparing the negative electrode of the secondary battery. As the negative electrode active material, artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate can be listed. The silicon-based material can be selected from one or more of elemental silicon, silicon oxide compounds (such as silicon monoxide), silicon-carbon composites, silicon-nitrogen composites and silicon alloys. The tin-based material can be selected from one or more of elemental tin, tin oxide compounds and tin alloys.

[0113] As an example, the negative electrode current collector has two surfaces opposite to 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.

[0114] In the secondary battery of the present application, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0115] In the secondary battery of the present application, the negative electrode film layer generally comprises a negative electrode active material and an optional binder, an optional conductive agent, and other optional additives, and is generally formed by coating and drying a negative electrode slurry. The negative electrode slurry coating is generally formed by dispersing the negative electrode active material, the optional conductive agent, and the binder in a solvent and stirring the mixture uniformly. The solvent may be N-methylpyrrolidone (NMP) or deionized water.

[0116] As an example, the conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0117] As an example, the binder can be selected from one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).

[0118] Other optional auxiliary agents include, for example, thickeners (such as sodium carboxymethyl cellulose (CMC-Na)).

[0119] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0120] [Electrolytes]

[0121] The present invention has no specific restrictions on the type of electrolyte, and the electrolyte can be selected according to the needs. For example, the electrolyte can be solid or liquid.

[0122] In some embodiments, the electrolyte is liquid and generally includes an electrolyte salt and a solvent.

[0123] As an example, the electrolyte salt can be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).

[0124] As an example, the solvent can be selected from one or more of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).

[0125] In some embodiments, the electrolyte may optionally include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, additives for improving battery overcharge performance, additives for improving battery high temperature performance, additives for improving battery low temperature performance, etc.

[0126] [Diaphragm]

[0127] The diaphragm separates the positive electrode sheet from the negative electrode sheet to prevent a short circuit inside the battery, while allowing active ions to pass through the diaphragm and move between the positive and negative electrodes. In the secondary battery of the present application, as a diaphragm that plays the above-mentioned role, a secondary battery diaphragm comprising a polymer substrate layer and a coating coated on the substrate layer as described above is used. In the diaphragm, the coating may include the organic-inorganic hybrid composite of the present application as described above or the coating composition of the present application as described above.

[0128] The present application has no particular restrictions on the type of polymer substrate layer, and any known polymer substrate layer with good chemical stability and mechanical stability can be used. In some embodiments, any known porous structure membrane for secondary batteries can be used as the substrate layer of the secondary battery separator for the present application. For example, the substrate layer can be selected from one or more of a glass fiber film, a non-woven film, a polyethylene (PE) film, a polypropylene (PP) film, a polyvinylidene fluoride film, and a multilayer composite film containing one or more of them. In some embodiments, a polyolefin microporous membrane common in the art can be used as the substrate layer of the secondary battery separator for the present application. As a non-limiting example, the polyolefin microporous membrane can be a polyethylene (PE) monolayer film, a polypropylene (PP) monolayer film, and a PP / PE / PP multilayer microporous membrane composited with PP and PE. For example, a PP-PE copolymer microporous film having a thickness of about 20 μm and an average pore size of about 80 nm can be used as the substrate layer of the secondary battery separator for the present application.

[0129] The organic-inorganic hybrid composite of the present application or the coating composition of the present application can be applied to a polymer substrate layer by methods common in the art to form a coating applied to the substrate layer. For example, a slurry comprising the organic-inorganic hybrid composite of the present application or the coating composition of the present application can be applied to at least one surface of the substrate layer of the secondary battery separator by conventional coating methods, such as blade coating, to form a wet coating on the surface. The solid content of the slurry can be from about 5% to about 10%, for example, about 9%. After the wet coating is dried, a coating is formed on at least one surface of the separator. The thickness of the coating can be about 1-8 μm, for example, about 5 μm.

[0130] In some embodiments, the secondary battery may be a lithium-ion secondary battery.

[0131] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0132] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte as described above.

[0133] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery can also be a soft shell, such as a pouch-type soft shell. The material of the soft shell can be plastic, and examples of plastic include polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0134] The present application has no particular limitation on the shape of the secondary battery, which can be cylindrical, square or any other shape. For example, Figure 1 The secondary battery 5 is a square structure as an example.

[0135] In some embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the diaphragm can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0136] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0137] Figure 3 4 is an example of a battery module. Figure 3 In the battery module 4, the plurality of secondary batteries 5 may be arranged in sequence along the length of the battery module 4. Of course, they may also be arranged in any other manner. The plurality of secondary batteries 5 may further be fixed by fasteners.

[0138] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0139] In some embodiments, the battery modules may be assembled into a battery pack. Those skilled in the art may select the number of battery modules contained in the battery pack according to the application and capacity of the battery pack.

[0140] Figure 4 and Figure 5 The battery pack 1 is used as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner in the battery box.

[0141] In addition, the present application also provides a device, which includes one or more of the secondary batteries, battery modules, or battery packs provided in the present application. The secondary batteries, battery modules, or battery packs can be used as power sources for the device, and can also be used as energy storage units for the device. The device can be, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0142] As an electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0143] Figure 6 This is an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0144] As another example, an electric device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be lightweight and thin, and may use a secondary battery as a power source.

[0145] The above summary of the invention of this application is not intended to describe every disclosed embodiment or every implementation in this application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each example, the enumeration is intended only as a representative group and should not be construed as exhaustive.

[0146] In the following preparations, examples, and application examples, if no specific conditions are specified, the steps described are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without manufacturer indication are commercially available conventional products.

[0147] Preparation of organic-inorganic hybrid composites

[0148] In summary, the organic-inorganic hybrid composite compound of the present application can be prepared by liquid phase coprecipitation. An acid, anhydride or salt containing the corresponding ligand L and a metal M or metal cluster M containing the corresponding a C bThe salt is stirred and mixed in water or a polar solvent such as ammonia, ethanol, methanol, DMF, etc., and the reaction is carried out at a temperature between room temperature and 150°C, and a substance that introduces defects, such as an acidic substance, an alkaline substance, a redox agent, etc., is added. After the reaction is completed, the reaction mixture is aged for about 1-48 hours. Thereafter, the solid product is recovered by filtration. The recovered solid product is activated at a temperature of about 140°C to about 160°C for about 8-12 hours to obtain the final organic-inorganic hybrid composite compound product.

[0149] Preparation Example 1

[0150] Weigh equimolar FeCl2 (127g) and Na4Fe(CN)6 (304g) as raw materials. The two raw materials are added to 10L deionized water respectively to prepare 0.1M FeCl2 solution and 0.1MNa4Fe(CN)6 solution. The two solutions are heated to about 80°C and maintained at this temperature. The FeCl2 solution is added dropwise to the Na4Fe(CN)6 solution at a rate of about 1mL / min to produce a coprecipitation reaction to obtain a precipitate. During the dropwise addition, an acidic substance, dilute hydrochloric acid (3.5g by mass based on pure HCl), is poured in at one time to introduce ligand defects. After the reaction is completed, the reaction mixture is aged at about 80°C for about 24 hours. Afterwards, the solid product is recovered by suction filtration. Subsequently, the recovered solid product is activated at a temperature of about 150°C for about 10 hours. Finally, 133g of solid product is obtained.

[0151] The solid product obtained is characterized to determine the chemical formula of the basic unit of the final organic-inorganic hybrid composite compound. Specifically, the solid product obtained is vacuum dried at 150°C as a sample to be tested to remove adsorbed water impurities. The sample is then subjected to ICP testing (SPECTRO BLUE, from SPECTRO Analytical Instruments GmbH) to determine that the percentages of Fe and Na are 37.76% and 11.97%, respectively. In addition, by carbon-sulfur testing (carbon-sulfur analyzer, CS844, from LECO Corporation) and elemental analysis testing (Elemental analysis) (Vario ELⅢ, from Elementar Analysensysteme GmbH), it is determined that the percentages of C and N are 22.93% and 26.75%, respectively. Through the above tests, it is determined that the empirical formula of the product is (CN) 2.79 Fe·Na 0.76The theoretical formula of the corresponding defect-free product was determined to be (CN)3Fe·Na by element valence determination and in-situ cold field emission gun double spherical aberration corrected transmission electron microscopy (Talos F200i, from Thermo Fisher Scientific Inc.). Based on the above results, it can be concluded that the organic-inorganic hybrid composite actually obtained in this preparation example has [(CN) 2.79 N 0.21 ]Fe·Na 0.76 In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 7.0%.

[0152] The obtained organic-inorganic hybrid composite material was characterized by scanning electron microscopy (SEM) (Sigma300, from Carl-Zeiss Jena GmbH). The obtained SEM photos are shown in Figure 7 middle.

[0153] Preparation Example 2

[0154] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 1, except that 0.6 g of dilute hydrochloric acid was added during the preparation, calculated as pure HCl. Finally, 141 g of a solid product was obtained.

[0155] The same characterization method as in Preparation Example 1 was used to determine that the organic-inorganic hybrid composite prepared in this preparation example had [(CN) 2.97 N 0.03 ]Fe·Na 0.95 In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 1.0%.

[0156] Preparation Example 3

[0157] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 1, except that 2.8 g of dilute hydrochloric acid (calculated as pure HCl) was added during the preparation process. Finally, 139 g of a solid product was obtained.

[0158] The same characterization method as in Preparation Example 1 was used to determine that the organic-inorganic hybrid composite prepared in this example had [(CN) 2.925 N 0.075 ]Fe·Na 0.90 In the organic-inorganic hybrid composite prepared in this example, the defect percentage is 2.5%.

[0159] Preparation Example 4

[0160] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 1, except that 9.7 g of dilute hydrochloric acid was added during the preparation, calculated as pure HCl. Finally, 118 g of a solid product was obtained.

[0161] The same characterization method as in Preparation Example 1 was used to determine that the organic-inorganic hybrid composite prepared in this example had [(CN) 2.46 N 0.54 ]Fe·Na 0.42 In the organic-inorganic hybrid composite prepared in this example, the defect percentage is 18.0%.

[0162] Preparation Example 5

[0163] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 1, except that 13.2 g of dilute hydrochloric acid was added during the preparation, calculated as pure HCl. Finally, 108 g of a solid product was obtained.

[0164] The same characterization method as in Preparation Example 1 was used to determine that the organic-inorganic hybrid composite prepared in this example had [(CN) 2.25 N 0.75 ]Fe·Na 0.2 In the organic-inorganic hybrid composite prepared in this example, the defect percentage is 25.0%.

[0165] Preparation Example 6

[0166] An organic-inorganic hybrid composite was prepared using essentially the same method as in Preparation Example 1, except that 0.1M MnCl₂ solution and 0.1M Na₄Mn(CN)₆ solution were prepared in 10L of deionized water, respectively, instead of the 0.1M FeCl₂ solution and 0.1M Na₄Fe(CN)₆ solution in Preparation Example 1, for the coprecipitation reaction. Furthermore, dilute hydrochloric acid was not added during the preparation process, and instead, ligand defects were introduced by continuously bubbling O₂. The O₂ flux was 1.7 × the total solution volume / hour. Finally, 132g of solid product was obtained.

[0167] By a test method similar to that in Preparation Example 1, the empirical formula of the product was determined to be (CN) 2.79 Mn·Na 0.76 In addition, by a method similar to that in Preparation Example 1, the theoretical formula of the corresponding defect-free product was determined to be (CN)3Mn·Na. Based on the above results, it can be concluded that the organic-inorganic hybrid composite actually obtained in this preparation example has [(CN)2.79 N 0.21 ]Mn·Na 0.76 In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 7.0%.

[0168] Preparation Example 7

[0169] An organic-inorganic hybrid composite was prepared using essentially the same method as in Preparation Example 6, except that a 0.1 M CoCl solution and a 0.1 M Na₄Co(CN)₆ solution were prepared in 10 L of deionized water, respectively, instead of the 0.1 M MnCl₂ solution and 0.1 M Na₄Mn(CN)₆ solution in Preparation Example 6, for coprecipitation. Finally, 136 g of a solid product was obtained.

[0170] By a test method similar to that in Preparation Example 1, the empirical formula of the product was determined to be (CN) 2.79 Co·Na 0.76 In addition, by a method similar to that in Preparation Example 1, the theoretical formula of the corresponding defect-free product was determined to be (CN)3Co·Na. Based on the above results, it can be concluded that the organic-inorganic hybrid composite actually obtained in this preparation example has [(CN) 2.79 N 0.21 ]Co·Na 0.76 In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 7.0%.

[0171] Preparation Example 8

[0172] An organic-inorganic hybrid composite was prepared using essentially the same method as in Preparation Example 6, except that a 0.1 M MnCl solution and a 0.1 M NaFe(CN) solution were prepared in 10 L of deionized water, respectively, instead of the 0.1 M MnCl solution and 0.1 M NaMn(CN) solution in Example 6, for coprecipitation. Finally, 136 g of a solid product was obtained.

[0173] By a test method similar to that in Preparation Example 1, the empirical formula of the product was determined to be (CN) 2.79 [Fe 0.5 Mn 0.5 ]·Na 0.76 In addition, by a method similar to that in Preparation Example 1, the theoretical formula of the corresponding product without defects was determined to be (CN)3[Fe 0.5 Mn 0.5 ]·Na. Based on the above results, it can be concluded that the organic-inorganic hybrid composite actually obtained in this preparation example has [(CN)2.79 N 0.21 ][Fe 0.5 Mn 0.5 ]·Na 0.76 In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 7.0%.

[0174] Preparation Example 9

[0175] An organic-inorganic hybrid composite was prepared using a method substantially identical to that in Preparation Example 1, except that Co(NO3)2 and 5-chlorobenzimidazole were used as raw materials, and 10 L of a mixed solvent (1:1) of H2O and DMF was used instead of the deionized water used in Preparation Example 1. 0.1 M Co(NO3)2 solution and 0.2 M 5-chlorobenzimidazole solution were used to replace the 0.1 M FeCl2 solution and 0.1 M Na4Fe(CN)6 solution in Preparation Example 1, respectively, for coprecipitation reaction. Furthermore, dilute hydrochloric acid was not added during the preparation process, but 3.3 g of NaOH was added to introduce ligand defects. Finally, 293 g of a solid product was obtained.

[0176] By a test method similar to that in Preparation Example 1, the empirical formula of the product was determined to be (cbIm) 1.86 Co. In addition, by a method similar to that in Preparation Example 1, the theoretical formula of the corresponding defect-free product was determined to be (cbIm)2Co. Based on the above results, it can be concluded that the organic-inorganic hybrid composite actually obtained in this preparation example has [(cbIm) 1.86 N 0.14 ] The basic unit shown in Co. In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 7.0%.

[0177] Preparation Example 10

[0178] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 9, except that 0.6 g of NaOH was added during the preparation process. Finally, 309 g of a solid product was obtained.

[0179] By a characterization method similar to that of Preparation Example 9, it was determined that the organic-inorganic hybrid composite prepared in this Preparation Example had [(cbIm) 1.98 N 0.02 ] The basic unit shown in Co. In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 1.0%.

[0180] Preparation Example 11

[0181] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 9, except that 1.2 g of NaOH was added during the preparation process. Finally, 305 g of a solid product was obtained.

[0182] By a characterization method similar to that of Preparation Example 9, it was determined that the organic-inorganic hybrid composite prepared in this Preparation Example had [(cbIm) 1.95 N 0.05 ] The basic unit shown in Co. In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 2.5%.

[0183] Preparation Example 12

[0184] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 9, except that 4.5 g of NaOH was added during the preparation process. Finally, 265 g of a solid product was obtained.

[0185] By a characterization method similar to that of Preparation Example 9, it was determined that the organic-inorganic hybrid composite prepared in this Preparation Example had [(cbIm) 1.64 N 0.36 ] The basic unit shown in Co. In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 18%.

[0186] Preparation Example 13

[0187] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 9, except that 8.4 g of NaOH was added during the preparation process. Finally, 246 g of a solid product was obtained.

[0188] By a characterization method similar to that of Preparation Example 9, it was determined that the organic-inorganic hybrid composite prepared in this Preparation Example had [(cbIm) 1.50 N 0.50 ] The basic unit shown in Co. In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 25%.

[0189] Preparation Example 14

[0190] An organic-inorganic hybrid composite was prepared using a method substantially identical to that used in Preparation Example 1, except that the raw materials used were trimesic acid tripotassium salt, trimesic acid, and Cu(NO3)2, and that 10 L of a 1:1 mixed solvent of H2O and EtOH was used instead of the deionized water used in Preparation Example 1. A 0.05 M solution of trimesic acid tripotassium salt, a 0.25 M solution of trimesic acid, and a 0.45 M solution of Cu(NO3)2 were prepared and mixed in sequence. Furthermore, 3.7 g of dilute hydrochloric acid was added during the preparation process, calculated as pure HCl. Finally, 758 g of a solid product was obtained.

[0191] By a test method similar to that in Preparation Example 1, the empirical formula of the product was determined to be (BTC) 1.86 Cu3·K. In addition, by a method similar to that in Preparation Example 1, the theoretical formula of the corresponding defect-free product was determined to be (BTC)2Cu3·K. Based on the above results, it can be concluded that the organic-inorganic hybrid composite actually obtained in this Preparation Example has [(BTC) 1.86 N 0.14 ] The basic unit represented by Cu3·K. In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 7.0%.

[0192] Preparation Example 15

[0193] An organic-inorganic hybrid composite was prepared using a method substantially identical to that used in Preparation Example 1, with the only differences being that the raw materials used were lithium terephthalate, terephthalic acid, Fe(ClO4)3, and HF. In place of the deionized water used in Preparation Example 1, 10 L of a 1:1 mixture of H2O and EtOH was used as solvent. A 0.05 M lithium terephthalate solution, a 0.05 M terephthalic acid solution, a 0.1 M Fe(ClO4)3 solution, and a 0.02 M HF solution were prepared and mixed into the solutions one by one. Furthermore, 3.7 g of dilute hydrochloric acid, calculated as pure HCl, was added during the preparation process. Finally, 188 g of a solid product was obtained.

[0194] By a test method similar to that in Preparation Example 1, the empirical formula of the product was determined to be (BDC) 0.93 [Fe(OH) 0.8 F 0.2 ]·Li 0.5 In addition, by a method similar to that in Preparation Example 1, the theoretical formula of the corresponding product without defects was determined to be (BDC)[Fe(OH) 0.8 F 0.2 ]·Li 0.5 According to the above results, it can be concluded that the organic-inorganic hybrid composite actually obtained in this preparation example has [(BDC) 0.93N 0.07 ][Fe(OH) 0.8 F 0.2 ]·Li 0.5 In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 7.0%.

[0195] Preparation Example 16

[0196] An organic-inorganic hybrid composite was prepared using a method substantially identical to that in Preparation Example 1, except that the raw materials used were magnesium tris(2-benzimidazolemethyl)amine (Mg3(NTB)2), tris(2-benzimidazolemethyl)amine, and Zn(NO3)2, and a 10L mixed solvent of H2O and EtOH (1:1) was used instead of the deionized water used in Preparation Example 1. 0.002M magnesium tris(2-benzimidazolemethyl)amine (Mg3(NTB)2) solution, 0.112M tris(2-benzimidazolemethyl)amine solution, and 0.24M Zn(NO3)2 solution were prepared in sequence and mixed in one by one; and the mass of the dilute hydrochloric acid added during the preparation process was 3.7g based on pure HCl. Finally, 519g of a solid product was obtained.

[0197] By a test method similar to that in Preparation Example 1, the empirical formula of the product was determined to be (NTB) 1.86 [Zn4O]·Mg 0.1 In addition, by a method similar to that in Preparation Example 1, the theoretical formula of the corresponding defect-free product was determined to be (NTB)2[Zn4O]·Mg 0.1 According to the above results, it can be concluded that the organic-inorganic hybrid composite actually obtained in this preparation example has [(NTB) 1.86 N 0.14 ][Zn4O]·Mg 0.1 In the organic-inorganic hybrid composite prepared in this preparation example, the defect percentage is 7.0%.

[0198] Comparative Preparation Example 1

[0199] A defect-free organic-inorganic hybrid composite (CN)3Fe·Na was prepared according to conventional methods. Specifically, equimolar FeCl2 (127 g) and Na4Fe(CN)6 (304 g) were weighed as raw materials. The two raw materials were respectively added to 10 L of deionized water to prepare 0.1 M FeCl2 solution and 0.1 M Na4Fe(CN)6 solution. The two solutions were heated to about 80°C and maintained at this temperature. The FeCl2 solution was added dropwise to the Li4Fe(CN)6 solution at a rate of about 1 mL / min to produce a coprecipitation reaction to obtain a precipitate. After the reaction was completed, the reaction mixture was aged at about 80°C for about 24 hours. Thereafter, the solid product was recovered by filtration. Subsequently, the recovered solid product was activated at a temperature of about 150°C for about 10 hours. Finally, 146 g of solid product was obtained.

[0200] There are no defects in the organic-inorganic hybrid composite prepared in this comparative preparation example, that is, the defect percentage is 0.

[0201] Comparative Preparation Example 2

[0202] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 1, except that 0.3 g of dilute hydrochloric acid was added during the preparation, calculated as pure HCl. Finally, 145 g of a solid product was obtained.

[0203] The same characterization method as in Preparation Example 1 was used to determine that the organic-inorganic hybrid composite prepared in this preparation example had [(CN) 2.985 N 0.015 ]Fe·Na 0.99 In the organic-inorganic hybrid composite prepared in this comparative preparation example, the defect percentage is 0.5%.

[0204] Comparative Preparation Example 3

[0205] The organic-inorganic hybrid composite was prepared using substantially the same preparation method as in Preparation Example 1, except that 23.1 g of dilute hydrochloric acid was added during the preparation, calculated as pure HCl. Finally, 97 g of a solid product was obtained.

[0206] The same characterization method as in Preparation Example 1 was used to determine that the organic-inorganic hybrid composite prepared in this preparation example had [(CN) 1.8 N 1.2 ]Fe·Na 0.1 In the organic-inorganic hybrid composite prepared in this comparative preparation example, the defect percentage is 40.0%.

[0207] Comparative Preparation Example 4

[0208] Using substantially the same method as in Comparative Preparation Example 1, a defect-free organic-inorganic hybrid composite (cbIm)2Co was prepared according to a conventional preparation method, except that the raw materials used were Co(NO3)2 and 5-chlorobenzimidazole, and 10 L of a mixed solvent (1:1) of H2O and DMF was used instead of the deionized water used in Comparative Preparation Example 1. 0.1 M Co(NO3)2 solution and 0.2 M 5-chlorobenzimidazole solution were prepared, respectively, to replace the 0.1 M FeCl2 solution and 0.1 M Na4Fe(CN)6 solution in Comparative Preparation Example 1 for coprecipitation reaction. Finally, 326 g of a solid product was obtained.

[0209] There are no defects in the organic-inorganic hybrid composite prepared in this comparative preparation example, that is, the defect percentage is 0.

[0210] Comparative Preparation Example 5

[0211] A defect-free organic-inorganic hybrid composite (BTC)2Cu3·K was prepared using essentially the same method as in Comparative Preparation Example 1, following conventional preparation methods. The only difference was that the raw materials used were trimesic acid tripotassium salt, trimesic acid, and Cu(NO3)2. In addition, a 10 L mixed solvent of H2O and EtOH (1:1) was used instead of the deionized water used in Preparation Example 1. A 0.05 M solution of trimesic acid tripotassium salt, a 0.25 M solution of trimesic acid, and a 0.45 M solution of Cu(NO3)2 were mixed in sequence. Finally, 832 g of a solid product was obtained.

[0212] There are no defects in the organic-inorganic hybrid composite prepared in this comparative preparation example, that is, the defect percentage is 0.

[0213] Comparative Preparation Example 6

[0214] Using substantially the same method as in Comparative Preparation Example 1, a defect-free organic-inorganic hybrid composite (BDC) [Fe(OH) 0.8 F 0.2 ]·Li 0.5 The only difference is that the raw materials used are lithium terephthalate, terephthalic acid, Fe(ClO4)3, and HF. 10 L of a 1:1 mixed solvent of H2O and EtOH is used instead of the deionized water used in Preparation Example 1. A 0.05 M solution of lithium terephthalate, a 0.05 M solution of terephthalic acid, a 0.1 M Fe(ClO4)3 solution, and a 0.02 M HF solution are prepared and mixed into the solutions one by one. Finally, 205 g of a solid product is obtained.

[0215] There are no defects in the organic-inorganic hybrid composite prepared in this comparative preparation example, that is, the defect percentage is 0.

[0216] Comparative Preparation Example 7

[0217] Using the same method as in Comparative Preparation Example 1, a defect-free organic-inorganic hybrid composite (NTB)2[Zn4O]·Mg 0.1 The only difference is that the raw materials used are tris(2-benzimidazolemethyl)amine magnesium complex (Mg3(NTB)2), tris(2-benzimidazolemethyl)amine, and Zn(NO3)2, and 10L of a mixed solvent of H2O and EtOH (1:1) is used instead of the deionized water used in Preparation Example 1. 0.002M tris(2-benzimidazolemethyl)amine magnesium complex (Mg3(NTB)2) solution, 0.112M tris(2-benzimidazolemethyl)amine solution, and 0.24M Zn(NO3)2 solution are prepared in sequence and mixed in one by one. Finally, 567g of solid product is obtained.

[0218] There are no defects in the organic-inorganic hybrid composite prepared in this comparative preparation example, that is, the defect percentage is 0.

[0219] Preparation of diaphragm

[0220] Example 1

[0221] A commercially available PP-PE copolymer microporous film (from Zhuogao Electronic Technology Co., Ltd., Model 20) with a thickness of 20 μm and an average pore size of 80 nm was used as the substrate layer. The organic-inorganic hybrid composite compound prepared in Preparation Example 1 above was mixed with a commercially available adhesive (polymethyl acrylate, from Hubei Nona Co., Ltd., CAS: 9003-21-8), a commercially available adhesive (acrylic acid-acrylate-acrylonitrile copolymer, from Hubei Nona Co., Ltd., CAS: 25686-45-7), a commercially available stabilizer (chemically pure sodium carboxymethyl cellulose, from Shanghai Changguang Enterprise Development Co., Ltd., CAS: 9004-32-4), and a commercially available wetting agent (polyoxyethylene ether, from Hubei Nona Co., Ltd., CAS: 27252-80-8) in a mass ratio of 85:6:3:3:3. Water was added during mixing to form a slurry with a solids content of approximately 9%. The slurry was applied to both surfaces of the substrate layer by doctor blade coating, forming a wet coating layer with a thickness of approximately 30 μm on each surface. The substrate layer with the wet coating layer was transferred to an oven and dried at approximately 80°C for approximately 60 minutes to obtain a separator with a coating layer thickness of approximately 5 μm.

[0222] The obtained membrane with coating was characterized by scanning electron microscopy (SEM) (Sigma 300, from Carl-Zeiss Jena GmbH). The obtained SEM photograph is shown in Figure 8 middle.

[0223] Examples 2-16 and Comparative Examples 1-7

[0224] The membranes were prepared in Examples 2-16 and Comparative Examples 1-7 by substantially the same method as in Example 1, except that the organic-inorganic hybrid composite compounds prepared in Preparation Examples 2-16 and Comparative Preparation Examples 1-7 were used instead of the organic-inorganic hybrid composite compound used in Example 1.

[0225] Example 17

[0226] A coating membrane was prepared by a method substantially the same as in Example 1, except that a certain weight proportion of the organic-inorganic hybrid composite compound was replaced by commercially available alumina (from Shandong Shuochuang Chemical Technology Co., Ltd.) so that the weight ratio of the organic-inorganic hybrid composite compound to alumina was 4:1.

[0227] Examples 18-20

[0228] Separators were prepared in Examples 18-20 by substantially the same method as in Example 17, except that the weight ratios of the organic-inorganic hybrid composite compound to alumina in Examples 18-20 were 3:2, 2:3, and 1:4, respectively.

[0229] Comparative Example 1

[0230] A commercially available PP-PE copolymer microporous film with a thickness of 20 μm and an average pore size of 80 nm (from Zhuogao Electronic Technology Co., Ltd.) was directly used as the separator (PP-PE bare film).

[0231] Comparative Example 2

[0232] A separator was prepared by substantially the same method as in Example 1, except that the organic-inorganic hybrid composite compound used in Example 1 was entirely replaced with the same weight of aluminum oxide.

[0233] Preparation of battery cells

[0234] Application Example 1

[0235] The active substance Na 0.9 Fe 0.5 Mn 0.5O2, conductive agent acetylene black (Denka Black, from Nippon Denka Co., Ltd.), and binder polyvinylidene fluoride (HSV 900, from Arkema Group) are fully stirred in an N-methylpyrrolidone solvent system in a weight ratio of 94:3:3 to uniformly mix to obtain a slurry with a solid content of 30%. The slurry is used to form a wet coating with a thickness of 250 μm on one side of an Al foil with a thickness of 12 μm by transfer coating. The Al foil with the wet coating is then transferred into an oven, dried at a temperature of 150°C for 60 minutes, and then cold pressed using a roller press at a pressure of 60 tons to obtain a positive electrode sheet, wherein the dry coating thickness on one side of the Al foil is 130 μm.

[0236] The active material hard carbon, the conductive agent acetylene black, the binder styrene-butadiene rubber, and the thickener sodium carboxymethyl cellulose were thoroughly stirred in a deionized water solvent system in a weight ratio of 95:2:2:1 to obtain a uniform mixture and a slurry with a solid content of 15%. The slurry was applied to one side of an Al foil with a thickness of 12 μm by a doctor blade method to form a wet coating with a thickness of 120 μm. The Al foil with the wet coating was then transferred to an oven and dried at a temperature of 150°C for 60 minutes. It was then cold pressed using a cold press with a pressure of 50 tons to obtain a negative electrode sheet, wherein the dry coating thickness on the Al foil was 60 μm.

[0237] The positive electrode sheet, the separator obtained in Example 1, and the negative electrode sheet were rolled up in sequence to form a bare cell with a wound laminate structure measuring 16 cm × 10 cm × 2.8 cm. This bare cell was placed in a steel case, into which 150 g of electrolyte was injected and encapsulated to obtain a cell. The electrolyte was a 1 M NaPF6 solution in propylene carbonate.

[0238] Application Examples 2-20, Comparative Application Examples 1-7, and Control Application Examples 1 and 2

[0239] The battery cells were prepared in Application Examples 2-20, Comparative Application Examples 1-7, and Control Application Examples 1 and 2 by a method substantially the same as that in Application Example 1, except that the separators in Examples 2-20, Comparative Examples 1-7, and Control Examples 1 and 2 were used instead of the separator used in Application Example 1.

[0240] Performance Testing

[0241] The separators prepared in Examples 1-20, Comparative Examples 1-7 and Control Examples 1 and 2, and the battery cells prepared in Application Examples 1-20, Comparative Application Examples 1-7 and Control Application Examples 1 and 2 were evaluated through the following performance tests.

[0242] Test Example 1

[0243] In this test example, the electrolyte wettability of each diaphragm was evaluated. Specifically, 1 drop (about 0.05 mL) of proton-type hydrophilic electrolyte with electrolyte (1M NaPF6 ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 1 / 1W / W solution) was dropped onto a horizontally placed diaphragm. After 5 minutes, the approximate area of ​​electrolyte infiltration was counted using the grid method. Specifically, the measurement method of the grid method is as follows: after 5 minutes, take a picture of the upper surface of the diaphragm from directly above, and then use an area of ​​0.01 cm in the picture. 2 The squares in the image cover all areas showing traces of electrolyte infiltration. The squares completely occupied by traces of electrolyte infiltration in the image are recorded as "completely infiltrated". Squares with an electrolyte infiltration area equal to or greater than half are also recorded as "completely infiltrated", while squares with an electrolyte infiltration area less than half are recorded as "uninfiltrated". The electrolyte wettability of the final separator is equal to the number of completely infiltrated squares × 0.01, expressed in cm 2 Expressed as a unit.

[0244] As an example, when the electrolyte wettability test was performed on the separators of Control Example 1, Comparative Example 1 and Example 1, the obtained photos are shown in FIG. Figure 9a 、 9b and 9c. Figure 9a 、 9b and 9c, the numbers of “completely wetted” squares are 43, 272, and 400, respectively. It can be concluded that the electrolyte wettability of the separators of Control Example 1, Comparative Example 1, and Example 1 is 0.43 cm 2 、2.72cm 2 and 4.00cm 2 .

[0245] Test Example 2

[0246] In this test example, the electrolyte retention rate of each diaphragm was evaluated. Specifically, a diaphragm with a size of 10 cm × 10 cm × 25 μm was taken (no coating was formed on the surface of the diaphragm of Control Example 1, so its thickness was 20 μm), and the dry weight W0 of the diaphragm was weighed. Then, the diaphragm was soaked in the electrolyte for 10 hours and then allowed to stand in a sealed container for 1 hour to saturate the electrolyte in the diaphragm, and then the wet weight W of the diaphragm was weighed. The electrolyte retention rate was calculated based on the following formula:

[0247] Electrolyte retention rate = [(W-W0) / W0] × 100%

[0248] It can be seen that the electrolyte retention rate obtained in this way not only represents the capacity of the diaphragm to hold the electrolyte, but also reflects the diaphragm's ability to retain the electrolyte.

[0249] The evaluation results of Test Examples 1 and 2 are summarized in Table 1. Table 1 also shows the chemical formula of the basic unit of the coating layer used in each separator and the defect percentage.

[0250] Table 1

[0251]

[0252]

[0253]

[0254]

[0255] Test Example 3

[0256] In this test, the injection time of each cell was evaluated. Specifically, the electrolyte was injected into the cell via vacuum injection, and the time required for the electrolyte to fully transfer from the discrete state to the interior of the separator and then to the interior of the positive and negative electrodes was recorded. This was done while ensuring that the resulting cell maintained normal performance (no performance drop due to electrolyte deficiency within 100 cycles).

[0257] Test Example 4

[0258] In this test example, the rate performance of each battery cell was evaluated. Specifically, the battery cell was placed in the test channel of the Arbin electrochemical workstation and charged at a constant current of 0.1C to a charge cut-off voltage of 4V, followed by constant voltage charging for 30 minutes. After that, the cell was discharged at a constant current of 0.1C and 1C to a discharge cut-off voltage of 2.5V, and the discharge capacity was recorded as 0.1C capacity and 1C capacity, respectively. The rate performance was calculated based on the following formula:

[0259] Rate performance = 1C capacity / 0.1C capacity × 100%.

[0260] Test Example 5

[0261] In this test example, the cycle performance of each battery cell was evaluated. Specifically, the battery cell was placed in the test channel of the Arbin electrochemical workstation, charged at a constant current rate of 1C to a charge cut-off voltage of 4V, left to stand for 5 minutes, and then discharged at a constant current rate of 1C to a discharge cut-off voltage of 2.5V. The discharge capacity was recorded, and the battery cell was left to stand for another 5 minutes. This cycle was repeated 100 times. The cycle performance was calculated based on the following formula:

[0262] Cycle performance = 100th cycle capacity / 1st cycle capacity × 100%.

[0263] As an example, the cycle performance curves of the battery cells of control application example 1, comparative application example 1 and application example 1 are shown in Figure 10 middle.

[0264] The evaluation results of Test Examples 3 to 5 are summarized in Table 2. Table 2 also shows the chemical formula of the basic unit of the coating layer used in each separator and the defect percentage.

[0265] Table 2

[0266]

[0267]

[0268] As can be seen from the results of the above tests, as shown in Table 1, the separators in Comparative Examples 1-7 and Examples 1-20 have improved performance in terms of electrolyte wettability and electrolyte retention compared to the bare membrane without a coating in Comparative Example 1 and the alumina-coated separator in Comparative Example 2. However, the performance improvement of the separators in Comparative Examples 1-7 is limited. Accordingly, the results shown in Table 2 indicate that the battery cells of Comparative Examples 1-7, each including these separators, have limited improvements in battery cell filling time, rate capability, and cycle performance.

[0269] In contrast, Examples 1-20 employ the defective organic-inorganic hybrid composite of this application in the coating, and the separators with such coatings exhibit further significant improvements in terms of electrolyte wettability and electrolyte retention. Accordingly, the battery cells comprising these separators in Application Examples 1-20 exhibit further significant improvements in terms of cell filling time, rate capability, and cycle performance.

[0270] In Examples 1-16, ligand defects within the defect percentage range specified in this application were introduced into several exemplary organic-inorganic hybrid composites included in the separator coating.

[0271] The results shown in Table 1 demonstrate that the separators of Examples 1-5 exhibit significantly superior electrolyte wettability and electrolyte retention compared to Comparative Example 1, which utilizes a defect-free organic-inorganic hybrid composite (CN)3Fe·Na. Correspondingly, the results shown in Table 2 demonstrate that the battery cells of Application Examples 1-5, each including these separators, significantly outperform the battery cell of Comparative Application Example 1 in terms of battery filling time, rate capability, and cycle performance.

[0272] Similarly, the results shown in Table 1 indicate that the separators of Examples 9-13 exhibit significantly superior performance in terms of electrolyte wettability and electrolyte retention compared to Comparative Example 4, which utilizes a defect-free organic-inorganic hybrid composite (cbIm)2Co. Accordingly, the results shown in Table 2 indicate that the cells of Application Examples 9-13, each including these separators, exhibit significantly superior cell filling time, rate capability, and cycle performance to the cell of Comparative Application Example 4.

[0273] In addition, as shown in Table 1, the results show that the corresponding defect-free organic-inorganic hybrid composites (BTC)2Cu3·K, (BDC)[Fe(OH) 0.8 F 0.2 ]·Li 0.5 and (NTB)2[Zn4O]·Mg 0.1 In comparison, the separators of Examples 14-16 exhibit significantly superior electrolyte wettability and electrolyte retention. Accordingly, the results shown in Table 2 indicate that the battery cells of Application Examples 14-16, including these separators, significantly outperform the corresponding battery cells of Comparative Application Examples 5-7 in terms of battery cell filling time, rate capability, and cycle performance.

[0274] Thus, it can be seen that the introduction of ligand defects within the defect percentage range specified in this application into the organic-inorganic hybrid composite can significantly promote the effect of improving the electrolyte wettability of the organic-inorganic hybrid composite as a diaphragm coating material, increase the electrolyte retention rate, and thus improve the battery cell injection rate, as well as the rate performance and cycle performance of the battery cell. The above-mentioned performance improvements brought about by the introduction of defects in the organic-inorganic hybrid composite can be widely applied to many different metals and / or ligands.

[0275] It is particularly noteworthy that, when using the same ligand (CN) and the same metal (Fe), only the defect percentage of the introduced defects is different, as shown in Table 1, compared with Comparative Example 2 with a lower defect percentage and Comparative Example 3 with a higher defect percentage, in Examples 1-5, the defect percentage of the organic-inorganic hybrid composite included in the coating of the diaphragm is within the range of 1-30% defined in this application, and the performance of the diaphragm in terms of electrolyte wettability and electrolyte retention rate is significantly superior. Accordingly, the results shown in Table 2 show that the battery cells of Application Examples 1-5, respectively including these diaphragms, are significantly superior to the battery cells of Comparative Application Examples 2 and 3 in terms of battery cell injection time, rate performance, and cycle performance.

[0276] In Examples 17-20, a coating with additional aluminum oxide (Al2O3) was applied to the separator, which improved the rate performance and cycle performance of the battery cell while ensuring that the separator's wettability was within a reasonable range. This may be because after the organic-inorganic hybrid composite and Al2O3 are blended, the two can be more tightly combined due to the complementary particle morphology; the organic-inorganic hybrid composite improves wettability, increases electrolyte retention, and increases the battery cell injection rate, while Al2O3 can provide a rigid and stable separator structure. The two work synergistically, achieving the best synergistic effect at the mixing ratio used in Example 18.

[0277] Industrial Applicability

[0278] The defective organic-inorganic hybrid composite of the present application, when applied to a coating for a secondary battery separator, improves the separator's electrolyte wettability and electrolyte retention, thereby reducing polarization and improving the secondary battery's rate performance and cycle life. Therefore, the present application is suitable for industrial applications.

Claims

1. A separator for a secondary battery, characterized in that: It includes: a polymer substrate layer; and A coating layer coated on the polymer substrate layer, the coating layer comprising a coating composition, the coating composition comprising an organic-inorganic hybrid composite, the organic-inorganic hybrid composite being composed of basic units represented by formula (I) periodically assembled along at least one spatial direction: [L x-i N i ][M a C b ]•A z (I) Wherein, in formula (I), M represents a first transition metal element, and M is selected from one or more of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn, C represents an atom, an atomic group or an anion that optionally forms a metal cluster with M, wherein C is selected from -O-, =O, O 2- 、S 2- 、F - , Cl - Br - , I - , CO, -OH and OH - One or more of L represents a metal M or a metal cluster M a C b An organic bridging ligand forming a coordination bond, wherein L is selected from cyano, benzimidazole ligands, porphyrin ligands, pyridine ligands, pyrazole ligands, pyrimidine ligands, piperidine ligands, pyrrolidine ligands, furan ligands, thiophene ligands, pyrazine ligands, piperazine ligands, pyridazine ligands, triazine ligands, tetrazine ligands, indole ligands, quinoline ligands, carbazole ligands, morpholine ligands, carbazole ligands and polycarboxylic acid ligands. At least one, one or more hydrogen atoms in L are optionally substituted by one or more substituents, each of which is independently selected from at least one of cyano, nitro, amino, aldehyde, carboxyl, halogen, C1-C6 alkyl, C1-C6 hydroxyalkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, C3-C8 cycloalkyl, C6-C10 aryl, C6-C10 heteroaryl, and any combination thereof, N indicates ligand deficiency, A represents an atom or cation capable of insertion and extraction, wherein A is an atom or cation of one or more metal elements selected from Li, Na, K, Rb, Cs, Sr, Zn, Mg and Ca, x is a value from 1 to 4, a is a value greater than 0 and less than or equal to 4, z is a value ranging from 0 to 2. 0 < i < x, and 0≤b:a≤1, The degree of defects of the organic-inorganic hybrid composite is represented by defect percentage i / x*100%, and the defect percentage is 1% to 30%.

2. The secondary battery separator according to claim 1, wherein x is a value ranging from 1 to 3.

3. The secondary battery separator according to claim 1, wherein a is a value ranging from 1 to 4.

4. The secondary battery separator according to claim 1, wherein z is a value ranging from 0 to 1.

5. The secondary battery separator according to claim 1, wherein The defect percentage is 2% to 20%.

6. The secondary battery separator according to claim 5, characterized in that The defect percentage is 2.5%-18%.

7. The secondary battery separator according to claim 5, wherein The defect percentage is 5% to 10%.

8. The secondary battery separator according to claim 1, wherein 1 / 2≤x:a≤3.

9. The secondary battery separator according to claim 1, wherein 1 / 4≤b:a≤1.

10. The secondary battery separator according to any one of claims 1 to 9, characterized in that The M is selected from one or more of Mn, Fe, Co, Cu and Zn.

11. The secondary battery separator according to any one of claims 1 to 9, characterized in that The C is -O- or -OH.

12. The secondary battery separator according to any one of claims 1 to 9, characterized in that The L is selected from at least one of a cyano group, a benzimidazole ligand and a polycarboxylic acid ligand.

13. The secondary battery separator according to claim 12, wherein The L is at least one selected from cyano, benzimidazole ligands, trimesic acid ligands and terephthalic acid ligands.

14. The secondary battery separator according to claim 12, wherein The L is at least one selected from cyano, 5-chlorobenzimidazole ligand, trimesic acid ligand (BTC), terephthalic acid ligand (BDC) and tris(2-benzimidazolemethyl)amine ligand (NTB).

15. The secondary battery separator according to any one of claims 1 to 9, characterized in that The A is Li or Na.

16. The secondary battery separator according to any one of claims 1 to 9, characterized in that The basic units represented by formula (I) are periodically assembled along at least one of the three spatial directions X', Y' and Z', and the three spatial directions X', Y' and Z' respectively form an angle of 0 to 75 degrees with the X direction, Y direction and Z direction of the Cartesian coordinate system.

17. The secondary battery separator according to claim 16, wherein The three spatial directions X', Y' and Z' respectively form angles of 5 to 60 degrees with the X direction, Y direction and Z direction of the Cartesian coordinate system.

18. The secondary battery separator according to claim 16, wherein The basic units represented by formula (I) are periodically assembled along at least one spatial direction of the X direction, the Y direction, and the Z direction of the Cartesian coordinate system.

19. The secondary battery separator according to any one of claims 1 to 9, characterized in that The number of the basic units represented by formula (I) periodically assembled along at least one spatial direction is 3 to 10,000.

20. The secondary battery separator according to any one of claims 1 to 9, characterized in that The content of the organic-inorganic hybrid composite is 12 wt % to 90 wt % based on the mass of the coating composition.

21. The secondary battery separator according to claim 20, wherein The content of the organic-inorganic hybrid composite is 17 wt % to 85 wt %.

22. The secondary battery separator according to claim 20, wherein The content of the organic-inorganic hybrid composite is 34 wt % to 68 wt %.

23. The secondary battery separator according to claim 20, wherein The coating composition also includes inorganic particles.

24. The secondary battery separator according to claim 23, wherein Based on the total mass of the organic-inorganic hybrid composite and the inorganic particles in the coating, the mass of the organic-inorganic hybrid composite accounts for 15 wt % to 85 wt %.

25. The secondary battery separator according to claim 24, wherein The mass proportion of the organic-inorganic hybrid composite is 20 wt % to 80 wt %.

26. The secondary battery separator according to claim 24, wherein The mass proportion of the organic-inorganic hybrid composite is 40 wt % to 80 wt %.

27. The secondary battery separator according to claim 23, wherein The inorganic particles are at least one selected from boehmite, zeolite, molecular sieve, alumina, aluminum oxyhydroxide, silicon dioxide, aluminum nitride, silicon carbide, magnesium oxide, calcium oxide, zinc oxide, zirconium oxide, titanium oxide and mixtures thereof.

28. A secondary battery, characterized in that: It includes: positive electrode; negative electrode; electrolytes; and The secondary battery separator according to any one of claims 1 to 27.

29. A battery module, characterized in that: It includes the secondary battery according to claim 28.

30. A battery pack, characterized in that: It includes the battery module according to claim 29.

31. An electrical device, characterized in that: It includes the secondary battery according to claim 28, the battery module according to claim 29, or the battery pack according to claim 30.

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