Aqueous metal ion battery and preparation method and power-using device thereof

Abstract

The present application relates to an aqueous metal ion battery, comprising a diaphragm, wherein the diaphragm comprises: a substrate; a ceramic coating on at least one surface of the substrate; and a polymer coating on the ceramic coating, wherein the polymer coating contains a thickener. The present application also relates to a method for preparing an aqueous metal ion battery and an electrical device.

Description

Technical Field

[0001] The present application relates to the technical field of secondary batteries, and in particular to an aqueous metal ion battery and a preparation method and an electrical device thereof. Background Art

[0002] In recent years, as the application scope of secondary batteries becomes wider and wider, secondary batteries are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.

[0003] Aqueous batteries refer to secondary batteries that use water as the electrolyte solvent. Aqueous batteries have gradually become a hot topic in secondary battery research due to their advantages such as high safety, environmental friendliness, and high ionic conductivity. However, the cycle performance and safety performance of existing aqueous batteries need to be further improved. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and its purpose is to provide an aqueous metal ion battery having good cycle performance and safety performance.

[0005] In order to achieve the above objectives, the present application provides an aqueous metal ion battery and a preparation method and an electrical device thereof.

[0006] A first aspect of the present application provides an aqueous metal ion battery, comprising a diaphragm, wherein the diaphragm comprises:

[0007] Base material;

[0008] a ceramic coating on at least one surface of the substrate; and

[0009] a polymer coating on the ceramic coating,

[0010] Wherein, the polymer coating comprises a thickener.

[0011] Therefore, the present application includes a thickener in the polymer coating of the aqueous metal ion battery separator. The thickener becomes more viscous after absorbing water, thereby enhancing the adhesion between the separator and the positive and negative electrode sheets, thereby solving the problem of the fluffy electrode assembly (battery cell) after cold pressing, and further improving the cycle performance and safety performance of the aqueous metal ion battery.

[0012] In any embodiment, the thickener includes at least one of cellulose, silicate, polyurethane and polyacrylic acid.

[0013] In any embodiment, the celluloses include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose.

[0014] In any embodiment, the silicates include aluminum silicate and sodium silicate.

[0015] In any embodiment, the polyurethanes include hydrophobically modified ethoxylated polyurethanes and modified polymers thereof.

[0016] In any embodiment, the polyacrylic acid includes polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid.

[0017] In any embodiment, the coating density of the thickener is 0.0000649-0.000195 mg / mm 2 (0.1-0.3mg / 1540.25mm 2 ), optionally 0.0000649-0.000130 mg / mm 2 (0.1-0.2mg / 1540.25mm 2 ). When the coating density of the thickener is within the above range, the cycle performance and safety performance of the aqueous metal ion battery can be further improved.

[0018] In any embodiment, the coating density of the polymer coating is 0.00039-0.00422 mg / mm 2 (0.6-6.5mg / 1540.25mm 2 ). When the coating density of the polymer coating is within the given range, good bonding between the separator and the positive and negative electrode sheets can be ensured.

[0019] In any embodiment, the weight percentage of the thickener in the polymer coating is 1.5%-50%. When the weight percentage of the thickener in the polymer coating is within the given range, the cycle performance and safety performance of the aqueous metal ion battery can be further improved without affecting the function of the polymer coating.

[0020] A second aspect of the present application provides a method for preparing an aqueous metal ion battery, wherein the aqueous metal ion battery comprises a diaphragm, and the diaphragm comprises:

[0021] Base material;

[0022] a ceramic coating on at least one surface of the substrate; and

[0023] a polymer coating on the ceramic coating,

[0024] The polymer coating comprises a thickener

[0025] The method for preparing an aqueous metal ion battery comprises the following steps:

[0026] (1) preparing a positive electrode sheet;

[0027] (2) preparing a negative electrode sheet;

[0028] (3) preparing the diaphragm;

[0029] (4) preparing an electrolyte;

[0030] (5) preparing the aqueous metal ion battery;

[0031] Wherein, the step (3) comprises:

[0032] (3-1) providing the substrate,

[0033] (3-2) providing a ceramic slurry, applying the ceramic slurry on at least one surface of the substrate and drying the slurry to form the ceramic coating, and

[0034] (3-3) Providing a polymer slurry containing a thickener, applying the polymer slurry on the ceramic coating layer and drying the polymer coating layer to obtain the separator.

[0035] Therefore, the method of the present application includes a thickener in the polymer coating of the aqueous metal ion battery separator in a simple manner, which can solve the problem of fluffy electrode assemblies (battery cells) after cold pressing, thereby improving the cycle performance and safety performance of the aqueous metal ion battery.

[0036] The third aspect of the present application provides an electrical device, comprising the aqueous metal ion battery of the first aspect of the present application or the aqueous metal ion battery prepared by the method of the second aspect of the present application.

[0037] The electrical device of the present application includes the aqueous metal ion battery of the present application, and thus has at least the same advantages as the aqueous metal ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of an electrode assembly (battery cell) according to one embodiment of the present application.

[0039] Figure 2 Schematic diagram of an aqueous metal ion battery according to one embodiment of the present application.

[0040] Figure 3 yes Figure 2 An exploded view of an aqueous metal ion battery according to one embodiment of the present application is shown.

[0041] Figure 4 is a schematic diagram of a battery module according to an embodiment of the present application.

[0042] Figure 5 It is a schematic diagram of a battery pack according to one embodiment of the present application.

[0043] Figure 6 yes Figure 5 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0044] Figure 7 It is a schematic diagram of an electrical device using an aqueous metal ion battery as a power source according to one embodiment of the present application.

[0045] Description of reference numerals:

[0046] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 aqueous metal ion battery; 51 shell; 52 electrode assembly; 53 top cover assembly DETAILED DESCRIPTION

[0047] Hereinafter, the aqueous metal ion battery of the present application, its preparation method and the implementation mode of the electrical device thereof will be specifically disclosed with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0048] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0049] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0050] 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.

[0051] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, it is mentioned that the method may also include step (c), which means that step (c) can 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.

[0052] If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0053] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": 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).

[0054] In the preparation process of secondary batteries, the electrode assembly (i.e., battery cell JR) composed of the positive electrode sheet, separator and negative electrode sheet will be heated in a tunnel furnace after winding to soften the polymer coating of the separator, and then transferred to a cold pressing plate for cold pressing to bond the separator and the positive and negative electrode sheets together. However, in some aqueous metal ion batteries, the battery cell JR is relatively thin, and the heat is dissipated quickly when cooling after passing through the tunnel furnace, the temperature of the polymer coating on the separator drops quickly, and the bonding with the positive and negative electrode sheets becomes poor, and fluffy batteries are prone to appear during cold pressing, thereby affecting the cycle performance and safety performance of the aqueous metal ion battery.

[0055] The present application adds a thickener to the polymer coating of the diaphragm. The thickener becomes more viscous after absorbing water, thereby improving the adhesion between the diaphragm and the positive and negative electrodes, thereby improving the cycle performance and safety performance of the aqueous metal ion battery.

[0056] In one embodiment of the present application, the present application proposes an aqueous metal ion battery, which includes a diaphragm, and the diaphragm includes:

[0057] Base material;

[0058] a ceramic coating on at least one surface of the substrate; and

[0059] Polymer coatings on ceramic coatings,

[0060] Wherein, the polymer coating comprises a thickener.

[0061] Although the mechanism is not yet clear, the applicant unexpectedly discovered that: by including a thickener in the polymer coating of the aqueous metal ion battery separator, the thickener can absorb water to increase the viscosity, thereby enhancing the viscosity between the separator and the positive and negative electrodes, thereby solving the problem of the battery cell becoming fluffy after cold pressing, and further improving the cycle performance and safety performance of the aqueous metal ion battery.

[0062] In addition, when the aqueous metal ion battery is an aqueous lithium ion battery, the lithium precipitation of the battery is also improved. This is because when the bonding between the diaphragm and the positive and negative pole pieces is good, the gap between the positive and negative pole pieces is small, and the lithium ion transmission distance is uniform and small; when the bonding is poor, the distance between the positive and negative pole pieces is uneven, the local distance is too large, the lithium ion transmission path is long, and lithium precipitation is easy. Therefore, the present application includes a thickener in the polymer coating, which can maintain good bonding between the diaphragm and the positive and negative pole pieces during cold pressing, thereby improving lithium precipitation, that is, improving the safety performance of the aqueous metal ion battery.

[0063] When the aqueous metal ion battery is an aqueous sodium ion battery, the thickener increases the adhesion between the electrode and the diaphragm, which can ensure that the sodium ion transmission distance at different positions is uniform, thereby preventing wrinkling.

[0064] In the present application, an aqueous metal ion battery is a battery whose electrolyte is an aqueous solution.

[0065] In some embodiments, the aqueous metal ion battery is an aqueous lithium, sodium, zinc, aluminum or vanadium ion battery.

[0066] In some embodiments, the polymer coating is in the form of islands.

[0067] In some embodiments, the thickener is an aqueous thickener, that is, a thickener that can play a thickening role in an aqueous system.

[0068] In some embodiments, the thickener includes at least one of celluloses, silicates, polyurethanes, and polyacrylic acids.

[0069] In some embodiments, the celluloses include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose.

[0070] In some embodiments, silicates include aluminum silicate and sodium silicate.

[0071] In some embodiments, the polyurethanes include hydrophobically modified ethoxylated polyurethanes and modified polymers thereof.

[0072] In some embodiments, the polyacrylic acid includes polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid.

[0073] In the present application, polyacrylic acids include salts thereof, such as sodium polypropylene, sodium polymethacrylate and the like.

[0074] In some embodiments, the number average molecular weight of cellulose is 100,000-1,000,000 g / mol; the number average molecular weight of polyurethane is 15,000-100,000 g / mol; the number average molecular weight of polyacrylic acid is 10,000-1,200,000 g / mol.

[0075] In the present application, the number average molecular weight is determined by gel permeation chromatography (GPC) in accordance with GB / T 21863-2008 "Gel Permeation Chromatography (GPC) Using Tetrahydrofuran as Eluent" (equivalent to the German standard DIN 55672-1:2007 "Gel Permeation Chromatography (GPC) Part 1: Using Tetrahydrofuran (THF) as Elution Solvent").

[0076] The hydrophobic main chain of cellulose associates with the residual water molecules in the electrode assembly (i.e., the battery cell JR) via hydrogen bonds, thereby increasing the viscosity of the system and existing stably in the aqueous metal ion battery.

[0077] After absorbing water, silicates swell to form flocculent substances with good suspension and dispersibility. They combine with an appropriate amount of water to form a colloid, which can release charged particles in water, increase the viscosity of the system, and exist stably in aqueous metal ion batteries.

[0078] The hydrophobic part in the polyurethane molecule associates with the hydrophobic part in the polymer emulsion molecule, the emulsion particles, etc. to form a three-dimensional network structure, providing high shear viscosity. The hydrophilic chains in the molecule produce hydrogen bonds through water molecules, further thickening.

[0079] Before polyacrylic acid powder comes into contact with water, the cross-linked acrylic polymers are tightly curled together. When dispersed in water, the cross-linked acrylic polymers begin to open, and the carboxyl groups are ionized to form -COO-. The repulsive force between the negative charges causes the molecular structure to fully unfold, making the fluidity worse and increasing the viscosity.

[0080] In some embodiments, the coating density of the thickener is 0.1-0.3 mg / 1540.25 mm 2 , optionally 0.1-0.2mg / 1540.25mm 2 , further optionally 0.2mg / 1540.25mm2 .

[0081] When the coating density of the thickener is too high, the function of the polymer coating will be affected; when the coating density of the thickener is too low, the above effect cannot be achieved. Therefore, when the coating density of the thickener is within the above range, the cycle performance and safety performance of the aqueous metal ion battery can be further improved.

[0082] Although the unit of coating density is sometimes expressed as "mg / 1540.25mm 2 ” is used for expression, but this expression is not intended to express or imply any specific requirement for the area.

[0083] In some embodiments, the coating density of the polymer coating is 0.6-6.5 mg / 1540.25 mm 2 When the coating density of the polymer coating is within the given range, good bonding between the separator and the positive and negative electrode sheets can be ensured.

[0084] In some embodiments, the weight percentage of the thickener in the polymer coating is 1.5%-50%. When the weight percentage of the thickener in the polymer coating is within the given range, better bonding effect can be achieved without affecting the function of the polymer coating.

[0085] In some embodiments, the ceramic coating has a thickness of 0.5-4 μm.

[0086] In some embodiments, the ceramic coating comprises ceramic particles and a binder, wherein the weight percentage of the ceramic particles is 60-98%, and the weight percentage of the binder is 2-40%.

[0087] In some embodiments, the ceramic particles are selected from boehmite (γ-AlOOH), alumina (Al 2 O 3 ), barium sulfate (BaSO 4 ), magnesium oxide (MgO), magnesium hydroxide (Mg(OH) 2 ), silicon dioxide (SiO 2 ), tin dioxide (SnO 2 ), titanium oxide (TiO 2 ), calcium oxide (CaO), zinc oxide (ZnO), zirconium oxide (ZrO 2 ), yttrium oxide (Y 2 O 3 ), nickel oxide (NiO), cerium oxide (CeO 2 ), zirconium titanate (SrTiO 3 ), barium titanate (BaTiO 3 ), magnesium fluoride (MgF 2 ) at least one of.

[0088] In some embodiments, the binder is selected from at least one of polyvinylidene fluoride, polyacrylate, polymethyl methacrylate, polyacrylonitrile, polyimide, polyethylene oxide, and polyvinyl alcohol.

[0089] In some embodiments, the polymer coating has a thickness of 1-20 μm.

[0090] In some embodiments, the polymer coating comprises a polymer and an aqueous thickener, wherein the polymer is PVDF, the weight percentage of the polymer is 50%-98.5%, and the weight percentage of the aqueous thickener is 1.5%-50%.

[0091] In some embodiments, the substrate is selected from at least one of glass fiber, non-woven fabric, polyethylene, and polypropylene.

[0092] In some embodiments, the thickness of the substrate is 5-30 μm.

[0093] In some embodiments, the aqueous metal ion battery is an aqueous sodium ion battery, an aqueous lithium ion battery, an aqueous zinc ion battery, or an aqueous aluminum ion battery.

[0094] In one embodiment of the present application, the present application proposes a method for preparing an aqueous metal ion battery, wherein the aqueous metal ion battery comprises a diaphragm, and the diaphragm comprises:

[0095] Base material;

[0096] a ceramic coating on at least one surface of the substrate; and

[0097] Polymer coatings on ceramic coatings,

[0098] The polymer coating comprises a thickener,

[0099] The method for preparing an aqueous metal ion battery comprises the following steps:

[0100] (1) preparing a positive electrode sheet;

[0101] (2) preparing a negative electrode sheet;

[0102] (3) preparing a diaphragm;

[0103] (4) preparing an electrolyte;

[0104] (5) Preparation of aqueous metal ion batteries;

[0105] Wherein, step (3) comprises:

[0106] (3-1) providing a substrate,

[0107] (3-2) providing a ceramic slurry, applying the ceramic slurry on at least one surface of a substrate and drying the ceramic slurry to form a ceramic coating, and

[0108] (3-3) A polymer slurry containing a thickener is provided, and the polymer slurry is applied on the ceramic coating layer and dried to form a polymer coating layer, thereby obtaining a separator.

[0109] Therefore, the method of the present application includes a thickener in a simple manner in the polymer coating of the aqueous metal ion battery separator, which can increase the viscosity after absorbing water, thereby enhancing the adhesion between the separator and the positive and negative electrode plates.

[0110] In some embodiments, in step (3-2), the coating may be gravure coating, and the gravure coating uses a coater, and the coater includes a gravure roller, the line number of the gravure roller is 50-400 LPI, and the speed of the gravure coating is 5-60 m / min.

[0111] In some embodiments, in step (3-2), the solid content of the ceramic slurry is 50-70%.

[0112] In some embodiments, in step (3-2), the drying temperature is 30-70°C.

[0113] In some embodiments, in step (3-3), the coating is spraying, and the spraying speed is 0.01-0.1 mL / min / mm 2 .

[0114] In some embodiments, in step (3-3), the drying temperature is 30-70°C.

[0115] In addition, the aqueous metal ion battery and the electrical device of the present application will be described below with reference to the drawings as appropriate.

[0116] Typically, an aqueous metal ion battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charge and discharge process, active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through. The positive electrode sheet, the negative electrode sheet and the electrolyte can use existing products for metal ion batteries.

[0117] [Positive electrode]

[0118] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material.

[0119] 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 any one or both of the two opposite surfaces of the positive electrode current collector.

[0120] In some embodiments, 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.).

[0121] In some embodiments, the positive electrode active material may adopt the positive electrode active material for aqueous metal ion batteries known in the art. As an example, for aqueous lithium ion batteries, the positive electrode active material may include at least one of the following materials: lithium phosphates containing olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 、LiMn 2 O 4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (Also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O 2 (Also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O 2 (Also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (Also referred to as NCM622 )、LiNi 0.8 Co 0.1 Mn 0.1 O 2 (Also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and its modified compounds, etc. Examples of lithium phosphates containing olivine structures may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, a composite material of lithium iron manganese phosphate and carbon. For aqueous sodium ion batteries, the positive electrode active material may include at least one of the following materials: Na 0.44 MnO 2 、NaMnO 2 、V 2 O 5 For aqueous zinc ion batteries, the positive electrode active material may include at least one of the following materials: MnO 2 , VO 2 、V 2 O 3 、V 2 O 5 , Prussian blue, etc. For aqueous aluminum ion batteries, the positive electrode active material may include at least one of the following materials: natural graphite, expanded commercial graphite, FeS 2 、V 2 O 5 、TiO 2 wait.

[0122] In some embodiments, the content of the positive electrode active material in the positive electrode film layer is 70-98 wt %, based on the total weight of the positive electrode film layer.

[0123] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0124] In some embodiments, the binder accounts for 0.1-15% by mass of the positive electrode film layer.

[0125] In some embodiments, the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0126] In some embodiments, the conductive agent accounts for 1-15% by mass of the positive electrode film layer.

[0127] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0128] [Negative electrode]

[0129] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0130] 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 any one or both of the two opposite surfaces of the negative electrode current collector.

[0131] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. 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.).

[0132] In some embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As an example, for aqueous lithium-ion batteries, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. For aqueous sodium-ion batteries, the negative electrode active material may include at least one of the following materials: activated carbon, NaTi 2 (PO 4 ) 3, polyimide (PI), etc. For aqueous zinc ion batteries, the negative electrode active material may be metallic zinc. For aqueous aluminum ion batteries, the negative electrode active material may be metallic aluminum. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0133] In some embodiments, the mass percentage of the negative electrode active material in the negative electrode film layer is 75% to 99%, and optionally 80% to 98%.

[0134] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one 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).

[0135] In some embodiments, the binder accounts for 0.1% to 3.5% by mass of the negative electrode film layer, and optionally 0.5% to 2.5% by mass.

[0136] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

[0137] In some embodiments, the conductive agent accounts for 0.1% to 5% by mass of the negative electrode film layer, and can be optionally 0.3% to 3% by mass.

[0138] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0139] In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0140] [Electrolytes]

[0141] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0142] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent, wherein in an aqueous metal ion battery, the solvent is water.

[0143] In some embodiments, for aqueous lithium ion batteries: the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate. For aqueous sodium ion batteries, the electrolyte salt may be selected from sodium hexafluorophosphate (NaPF 6 ), sodium perchlorate (NaClO 4 ) etc. For aqueous zinc ion batteries, the electrolyte salt may be selected from: zinc sulfate, zinc tetrafluoroborate, zinc nitrate, zinc chloride. For aqueous aluminum ion batteries, the electrolyte salt may be selected from: AlCl 3 、Al 2 (SO 4 ) 3 、Al(NO 3 ) 3 wait.

[0144] In some embodiments, the concentration of the electrolyte salt is, for example, 0.3 mol / L (mole / liter) or more, optionally 0.7 mol / L or more, and 1.7 mol / L or less, optionally 1.2 mol / L or less.

[0145] In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0146] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly (ie, a battery cell JR) by a winding process or a lamination process.

[0147] like Figure 1 As shown, the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. The separator includes a substrate, a ceramic coating and a polymer coating, and the polymer coating contains a thickener.

[0148] In some embodiments, the thickness of the electrode assembly (ie, the battery cell JR) is 5-60 mm.

[0149] In some embodiments, the aqueous metal ion battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0150] In some embodiments, the outer packaging of the aqueous metal ion battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the aqueous metal ion battery can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed.

[0151] The present application has no particular restrictions on the shape of the aqueous metal ion battery, which may be cylindrical, square or any other shape. For example, Figure 2 The aqueous metal ion battery 5 is a square structure as an example.

[0152] In some embodiments, reference Figure 3 , the outer packaging may include a shell 51 and a cover plate 53. Among them, 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 infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the aqueous metal ion battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0153] The aqueous metal ion battery may be in the form of a battery cell, a battery module, or a battery pack. The battery module and the battery pack may include a battery cell, and the battery pack may also include a battery module.

[0154] In some embodiments, aqueous metal ion batteries in the form of battery cells can be assembled into battery modules. The number of aqueous metal ion batteries in the form of battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0155] Figure 4 4 is an example of a battery module. Figure 4 In the battery module 4, a plurality of aqueous metal ion batteries 5 in the form of battery cells may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of aqueous metal ion batteries 5 in the form of battery cells may be fixed by fasteners.

[0156] Optionally, the battery module 4 may further include a housing having a housing space, and a plurality of aqueous metal ion batteries 5 in the form of battery cells are housed in the housing space.

[0157] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

[0158] Figure 5 and Figure 6 1 is a battery pack 1 as an example. Figure 5 and Figure 6 The battery pack 1 may include a battery box and a plurality of 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 a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0159] In addition, the present application also provides an electric device, which includes at least one of the battery cells, battery modules, or battery packs provided in the present application. The battery cells, battery modules, or battery packs can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include 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., but are not limited thereto.

[0160] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0161] Figure 7 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. In order to meet the power consumption device's requirements for high power and high energy density of aqueous metal ion batteries, a battery pack or a battery module can be used.

[0162] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery cell may be used as a power source.

[0163] Example

[0164] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0165] Example 1

[0166] (1) Preparation of positive electrode sheet

[0167] The positive electrode active material Na 0.44 MnO 2 , PVDF and conductive agent carbon black are mixed evenly in an appropriate amount of solvent N-methylpyrrolidone (NMP) at a weight ratio of 8:1:1 to obtain positive electrode slurry, which is then coated on the positive electrode current collector aluminum foil, and then dried, cold pressed, slit, and cut to obtain a positive electrode sheet. The surface density of the positive electrode sheet is 2.5 mg / mm 2 , compacted density is 2.0g / cm 3 ;

[0168] (2) Preparation of negative electrode sheet

[0169] The negative electrode active material activated carbon, conductive agent carbon black, binder styrene butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC-Na) are mixed evenly in a proper amount of solvent deionized water at a weight ratio of 90:5:3.1:1.9 to obtain a negative electrode slurry, which is then coated on the negative electrode current collector copper foil, and then dried, cold pressed, slit, and cut to obtain a negative electrode sheet. The surface density of the negative electrode sheet is 1.45 mg / mm 2 , compacted density is 1.5g / cm 3 ;

[0170] (3) Preparation of diaphragm

[0171] (3-1) providing a polyethylene (PE) film having a thickness of 7 μm as a substrate,

[0172] (3-2) Ceramic particles Al 2 O 3 and binder PVDF are mixed uniformly in an appropriate amount of solvent deionized water at a weight ratio of 7:1 to obtain a ceramic slurry with a solid content of 60%, and the ceramic slurry is coated on both surfaces of the substrate by a coating machine and dried to form a ceramic coating with a single-side thickness of 2 μm. The line number of the gravure roller of the coating machine is 150 LPI, the coating speed is 10 m / min, the drying temperature is 40°C, the drying time is 2 hours, and

[0173] (3-3) The polymer PVDF and sodium polyacrylate (number average molecular weight of 15,000 g / mol) were mixed uniformly at a weight ratio of 6:1 to obtain a polymer slurry, and the polymer slurry was sprayed onto the ceramic coating, and dried to form an island-shaped polymer coating, thereby obtaining a diaphragm. The weight and thickness of the polymer coatings on both sides were consistent, and the spraying speed was 0.3 mL / min / mm 2 The coating density of the polymer coating is 1.4mg / 1540mm 2, the coating density of sodium polyacrylate is 0.2mg / 1540mm 2 ; The drying temperature is 40° C. and the drying time is 5 hours to obtain a separator;

[0174] (4) Preparation of electrolyte

[0175] Provide 1M Na at pH 7 2 SO 4 An aqueous solution is used as the electrolyte;

[0176] (5) Preparation of aqueous metal ion batteries

[0177] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is placed between the positive and negative electrode sheets to play an isolating role, and then wound to obtain an electrode assembly (whose thickness is 25 mm); the electrode assembly is placed in an outer package, and the prepared electrolyte is injected into the dried secondary battery. After vacuum packaging, standing, formation, and shaping processes, an aqueous sodium ion battery with a capacity of 71Ah is obtained.

[0178] Embodiment 2-4

[0179] The preparation method of the aqueous sodium ion battery of Examples 2-4 is similar to that of the aqueous sodium ion battery of Example 1, except that the mass ratio of each substance in the polymer slurry is adjusted so that the coating density of sodium polyacrylate is 0.1 mg / 1540 mm 2 、0.3mg / 1540mm 2 and 0.4mg / 1540mm 2 .

[0180] Embodiment 5-7

[0181] The preparation method of the aqueous sodium ion battery of Examples 5-7 is similar to the preparation method of the aqueous sodium ion battery of Example 1, except that sodium polyacrylate is replaced by methyl cellulose (number average molecular weight of 200,000 g / mol), aluminum silicate and polyurethane (purchased from Rohm and Haas Company, USA, with a number average molecular weight of 35,000 g / mol), respectively.

[0182] Embodiment 8-9

[0183] The preparation method of the aqueous sodium ion battery of Examples 8-9 is similar to that of the aqueous sodium ion battery of Example 1, except that the coating density of the polymer coating is 6.5 mg / 1540 mm 2 and 0.6mg / 1540mm 2 , the coating density of the thickener is 0.1mg / 1540mm 2 and 0.3mg / 1540mm 2 .

[0184] Comparative Example 1

[0185] The preparation method of the aqueous sodium ion battery of Comparative Example 1 is similar to that of the aqueous sodium ion battery of Example 1, except that in step (3-3), sodium polyacrylate is not added, and the coating density of the polymer coating is 1.5 mg / 1540 mm 2 .

[0186] 3. Performance Test

[0187] 1. Test method for the inner ring temperature of the electrode assembly after cooling for 4 minutes

[0188] A temperature sensing line TT-K-40-SLE-15 was arranged in the inner circle of the electrode assembly to detect the temperature of the innermost circle of the electrode assembly after cooling for 4 minutes.

[0189] 2. Capacity retention rate test method

[0190] In an environment of 25°C, the first charge and discharge are performed, and constant current and constant voltage charging is performed at an equivalent charging current of 2.2C until the upper limit voltage is 2V. Then, constant current discharge is performed at a discharge current of 1C until the final voltage is 0.5V, and the first discharge capacity value Cn is recorded. Subsequently, 2.2Cn / 1Cn, 0.5-2.0V continuous charging and discharging cycles are performed, the discharge capacity value during the cycle is recorded, and the cycle capacity retention rate is calculated. The capacity retention rate of the Nth cycle = (discharge capacity of the Nth cycle / discharge capacity of the first cycle) × 100%.

[0191] 3. Wrinkle Degree Test Method

[0192] The secondary battery was subjected to a cyclic charge and discharge procedure, with the charge and discharge currents being 2.2C and 1C, respectively, and the number of cycles being 2000. After the cyclic charge and discharge procedure was completed, the secondary battery was disassembled to evaluate the degree of wrinkling of the negative electrode sheet.

[0193] The wrinkle degree assessment method is as follows:

[0194] No wrinkles: Individual electrode components have no wrinkle areas

[0195] First-level wrinkling: the maximum area of ​​a single wrinkled area is ≤5×5mm 2 , the number of wrinkled areas of a single electrode assembly is ≤1;

[0196] Second level wrinkling: 5×5mm 2 <The maximum area of ​​a single wrinkled area ≤ 10×10mm 2 , the number of wrinkled areas of a single electrode assembly is ≤1;

[0197] Level 3 wrinkling: does not meet the judgment conditions of the first two levels.

[0198] The above embodiments and comparative examples were tested according to the above process, and the specific values ​​are shown in Table 1.

[0199]

[0200] As can be seen from Table 1, the present application can significantly improve the cycle performance and / or safety performance of the aqueous metal ion battery by using a thickener in the polymer coating of the diaphragm. In particular, by further selecting the coating density of the thickener, the coating density of the polymer coating and the weight percentage of the thickener, the cycle performance and / or safety performance can be further improved. In comparison, Comparative Example 1 in which the polymer coating of the diaphragm does not contain a thickener is inferior to Examples 1-9 in terms of both cycle performance and safety performance.

[0201] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. An aqueous metal ion battery comprising a diaphragm and an electrolyte, The diaphragm comprises: Base material; a ceramic coating on at least one surface of said substrate; as well as a polymer coating on the ceramic coating, wherein the polymer coating comprises a thickener; The solvent of the electrolyte is water.

2. The aqueous metal ion battery according to claim 1, wherein: The thickener includes at least one of cellulose, silicate, polyurethane and polyacrylic acid.

3. The aqueous metal ion battery according to claim 2, wherein: The celluloses include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose.

4. The aqueous metal ion battery according to claim 2, wherein: The silicates include aluminum silicate and sodium silicate.

5. The aqueous metal ion battery according to claim 2, wherein: The polyurethanes include hydrophobically modified ethoxylated polyurethanes and modified polymers thereof.

6. The aqueous metal ion battery according to claim 2, wherein: The polyacrylic acid includes polyacrylic acid, polymethacrylic acid or a copolymer of acrylic acid and methacrylic acid.

7. The aqueous metal ion battery according to claim 1 or 2, wherein: The coating density of the thickener is 0.1-0.3 mg / 1540.25 mm 2 , optionally 0.1-0.2mg / 1540.25mm 2 .

8. The aqueous metal ion battery according to claim 1 or 2, wherein: The coating density of the polymer coating is 0.6-6.5 mg / 1540.25 mm 2 .

9. The aqueous metal ion battery according to claim 1 or 2, wherein: The weight percentage of the thickener in the polymer coating is 1.5%-50%.

10. A method for preparing an aqueous metal ion battery, the aqueous metal ion battery comprising a diaphragm and an electrolyte, the diaphragm comprising: Base material; a ceramic coating on at least one surface of said substrate; as well as a polymer coating on the ceramic coating, The polymer coating comprises a thickener; The solvent of the electrolyte is water, The method for preparing an aqueous metal ion battery comprises the following steps: (1): Prepare the positive electrode sheet; (2): Preparation of negative electrode sheet; (3): preparing the diaphragm; (4): preparing electrolyte; (5): preparing the aqueous metal ion battery; Wherein, the step (3) comprises: (3-1): Providing the substrate, (3-2): providing a ceramic slurry, applying the ceramic slurry on at least one surface of the substrate and drying the ceramic slurry to form the ceramic coating, and (3-3): Providing a polymer slurry containing a thickener, applying the polymer slurry on the ceramic coating layer and drying the polymer coating layer to obtain the separator.

11. An electrical device, wherein: An aqueous metal ion battery comprising any one of claims 1 to 9 or an aqueous metal ion battery prepared by the method of claim 10.

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