Calcium metal battery based on high-conductivity composite current collector and electric device

Abstract

The invention relates to the technical field of secondary batteries, in particular to a calcium metal battery based on a high-conductivity composite current collector and an electric device. The calcium metal battery comprises a negative pole piece, a positive pole piece, electrolyte and an isolating membrane, the negative electrode piece comprises a negative electrode current collector, and the negative electrode current collector comprises a negative electrode supporting layer, a negative electrode metal layer arranged on at least one surface of the negative electrode supporting layer and a negative electrode ion transmission layer arranged on the surface, deviating from the negative electrode supporting layer, of the negative electrode metal layer; the negative ion transport layer comprises a conductive polymer C and a binder C; the positive pole piece comprises a modified positive pole material, the modified positive pole material comprises a positive pole material and a positive pole ion transport layer coating the positive pole material, and the positive pole ion transport layer comprises a conductive polymer D. The calcium metal battery provided by the invention has excellent cycle stability, and can still keep over 80% of capacity after 370 charge-discharge cycles.

Description

Technical Field

[0001] The present application relates to the technical field of secondary batteries, and particularly to a calcium metal battery and an electrical device based on a highly conductive composite current collector. Background Art

[0002] With the rapid development of emerging industries such as energy storage systems, power batteries, and smart wearable devices, higher requirements are put forward for the energy density, cost, and safety performance of secondary batteries. Multivalent metal batteries with active ions such as calcium, magnesium, zinc, and aluminum have received extensive attention due to their low cost, high reserves, and high safety.

[0003] Among multivalent metal batteries, the calcium metal battery has particularly prominent features: (1) Calcium is abundant in the earth's crust, ranking fifth in abundance, 2500 times higher than lithium; (2) The volume specific capacity of the calcium negative electrode is 2072 mAh / mL, and the mass specific capacity is 1337 mAh / g, and it has a low reduction potential, and its standard reduction potential (2.87 V vs. SHE) is closest to that of lithium (3.04 V vs. SHE); (3) Compared with other multivalent metal ions, calcium ions have a large ionic radius and a low charge density, which is beneficial to promoting the kinetic performance of the positive electrode reaction. Therefore, calcium metal batteries have broad development prospects in fields such as large-scale power grids, energy storage systems, and power batteries. However, at present, calcium metal batteries have the problem of low cycle life. Summary of the Invention

[0004] Based on this, it is necessary to provide a calcium metal battery and an electrical device based on a highly conductive composite current collector to solve the problem of low cycle life of calcium metal batteries.

[0005] The above object of the present application is achieved by the following technical solutions:

[0006] In the first aspect of the present application, a calcium metal battery based on a highly conductive composite current collector is provided, including a negative electrode sheet, a positive electrode sheet, an electrolyte, and a separator;

[0007] The negative electrode sheet includes a negative current collector, and the negative current collector includes a negative support layer, a negative metal layer provided on at least one surface of the negative support layer, and a negative ion transport layer provided on the surface of the negative metal layer facing away from the negative support layer. The negative ion transport layer includes a conductive polymer C and a binder C;

[0008] The positive electrode sheet includes a modified positive electrode material, and the modified positive electrode material includes a positive electrode material and a positive ion transport layer covering the positive electrode material. The positive ion transport layer includes a conductive polymer D.

[0009] In some embodiments, the negative electrode support layer includes a polymer-based film and a conductive agent A, and the conductive agent A is dispersed in the polymer-based film;

[0010] The polymer-based film is provided with a plurality of through holes, and the through holes are filled with a conductive composition, and the conductive composition includes a conductive polymer B, a conductive agent B, and a binder B.

[0011] In some embodiments, each of the conductive polymer B, the conductive polymer C, and the conductive polymer D independently includes one or more of polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene), poly(3-hexylthiophene), poly(3-dodecylthiophene), poly(3-dodecylthiophene-3-hexyl-3-triethylene glycol), and poly(3-octylpyrrole): poly(styrenesulfonic acid).

[0012] In some embodiments, each of the conductive agent A and the conductive agent B independently includes one or more of an inorganic carbon material and a material containing a metal element; the inorganic carbon material includes one or more of conductive carbon black, conductive graphite, acetylene black, Ketjen black, carbon quantum dots, carbon nanotubes, carbon nanofibers, graphene, and fullerenes; the material containing a metal element includes one or more of copper, aluminum, nickel, gold, silver, and MXene materials.

[0013] In some embodiments, each of the binder B and the binder C independently includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, hydrogenated nitrile rubber, polyvinyl alcohol, polymethacrylic acid, polymethyl methacrylate, polyacrylic acid, sodium polyacrylate, polyacrylamide, sodium alginate, sodium carboxymethyl cellulose, and carboxymethyl chitosan.

[0014] In some embodiments, the material of the negative electrode metal layer includes calcium, tin, a calcium-tin alloy, a calcium-bismuth alloy, or a calcium-antimony alloy.

[0015] In some embodiments, the mass ratio of the polymer-based film to the conductive agent A is 100: (1 to 30).

[0016] In some embodiments, the mass ratio of the conductive polymer B, the conductive agent B, and the binder B is 100: (1 to 50): (1 to 15).

[0017] In some embodiments, the mass ratio of the conductive polymer C to the binder C is 100: (1 to 15).

[0018] In some embodiments, the thickness of the negative electrode ion transport layer is 0.5 μm to 2 μm.

[0019] In some embodiments, the thickness of the negative electrode metal layer is 0.5 μm to 10 μm.

[0020] In some embodiments, the thickness of the negative electrode support layer is 4 μm to 8 μm.

[0021] In some embodiments, the aperture of the through hole is 10 μm to 100 μm, and the distance between adjacent two through holes is 500 μm to 4000 μm.

[0022] In some embodiments, the positive electrode material includes one or more of prussian blue compounds, transition metal oxides, transition metal sulfides, and spinel compounds.

[0023] In some embodiments, the mass ratio of the positive electrode material to the conductive polymer D is 2:(0.8 to 1.2).

[0024] In some embodiments, the preparation method of the modified positive electrode material includes an in-situ polymerization encapsulation method.

[0025] In some embodiments, the separator includes a base film and a MOF coating provided on at least one surface of the base film, and the MOF coating includes a silane-modified calcium-based MOF material.

[0026] In some embodiments, the organic ligand of the calcium-based MOF material includes one or more of 2-aminoterephthalic acid and 2,3-diaminoterephthalic acid.

[0027] In some embodiments, the silane includes one or more of (3-glycidyloxypropyl)trimethoxysilane, (3-glycidyloxypropyl)triethoxysilane, and (3-glycidyloxypropyl)dimethoxysilane.

[0028] In some embodiments, the molar ratio of the calcium-based MOF material to the silane is 1:(1 to 15).

[0029] In some embodiments, the thickness of the MOF coating is 0.5 μm to 2 μm.

[0030] In some embodiments, the electrolyte includes a calcium salt, an organic solvent, and an additive, and the additive includes one or more of trimethoxyphenylsilane and 2-cyano-3-fluoropyridine-5-boronic acid pinacol ester.

[0031] In some embodiments, the calcium salt includes one or more of calcium hexafluorophosphate, calcium tetrafluoroborate, calcium borohydride, calcium perchlorate, calcium bis(trifluoromethanesulfonyl)imide, and calcium trifluoromethanesulfonate.

[0032] In some embodiments, the concentration of the calcium salt in the electrolyte is 0.1 mol / L to 10 mol / L.

[0033] In some embodiments, the organic solvent includes one or more of ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl butyrate, ethyl propionate, methyl propionate, propylene carbonate, γ-butyrolactone, acetonitrile, ethyl acetate, propyl formate, methyl formate, methyl acetate, tetrahydrofuran, toluene, and xylene.

[0034] In some embodiments, the mass fraction of trimethoxyphenylsilane in the electrolyte is 0.1% - 5%.

[0035] In some embodiments, the mass fraction of 2-cyano-3-fluoropyridine-5-boronic acid pinacol ester in the electrolyte is 0.1% - 1%.

[0036] In the second aspect of the present application, an electrical device is provided, including the calcium metal battery as described above.

[0037] The present application has at least the following beneficial effects:

[0038] In the calcium metal battery provided by the present application, the negative electrode current collector in the negative electrode sheet includes a negative electrode support layer, a negative electrode metal layer, and a negative electrode ion transport layer, which belongs to a composite current collector. Compared with a metal foil of the same thickness, it has the characteristic of lighter mass, which helps to improve the mass energy density of the battery cell. Among them, the negative electrode ion transport layer includes a conductive polymer C, which contains a large number of conjugated π bonds and can effectively conduct electrons; during the calcium ion deposition process, the conjugated π bonds are enriched with a large number of electrons and exhibit electronegativity, which can accelerate the migration of calcium ions through Coulomb attraction and provide abundant negative charges to promote the reduction reaction and uniform deposition of calcium ions; during the calcium ion stripping process, the conjugated π bonds lose electrons and exhibit electropositivity, which can accelerate the oxidation of calcium atoms to form calcium ions and promote the migration of calcium ions from the negative electrode to the electrolyte through Coulomb repulsion. At the same time, the positive electrode sheet includes a modified positive electrode material, which forms a positive electrode ion transport layer by coating the positive electrode material with a conductive polymer D. On the one hand, it can promote the migration and diffusion of calcium ions and improve the kinetic performance, and on the other hand, it has a protective effect on the positive electrode material, thereby improving the structural stability of the modified positive electrode material. Therefore, the calcium metal battery provided by the present application has excellent cycle stability. In some of these embodiments, it can still maintain more than 80% of the capacity after 370 charge-discharge cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more fully understand the present application and its beneficial effects, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0040] Figure 1 Schematic structural diagram of the negative current collector in an embodiment of the present application;

[0041] Figure 2 Schematic structural diagram of the positive electrode sheet in an embodiment of the present application;

[0042] Figure 3 Schematic structural diagram of the separator in an embodiment of the present application.

[0043] Reference numerals: 11, negative electrode support layer; 11a, polymer-based film; 11b, conductive composition; 12, negative electrode metal layer; 13, negative electrode ion transport layer; 21, positive electrode support layer; 22, positive electrode metal layer; 23, positive electrode active layer; 31, base film; 32, MOF coating. Detailed Description of the Invention

[0044] To facilitate the understanding of the present application, the present application will be further described in detail below in conjunction with specific embodiments. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0046] In the present application, the meaning of "and / or" includes any and all combinations of one or more of the related listed items. The meaning of "at least one" is more than one, such as one, two or more. The meaning of "multiple" or "several" is at least two, such as two, three, etc., and the meaning of "multiple layers" is at least two layers, such as two layers, three layers, etc., unless otherwise clearly and specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0047] When a numerical range is disclosed in the present application, the above range is considered continuous and includes the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to an integer, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed in the present application should be understood to include any and all sub-ranges subsumed therein.

[0048] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c) in sequence, or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0049] In this application, "above" or "below" both include the number itself. For example, below 1 includes 1.

[0050] The temperature parameter in this application, unless otherwise specified, allows for both constant temperature treatment and variation within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0051] In this application, room temperature refers to indoor temperature, normal temperature, or general temperature. Generally, the range of room temperature can be any one of the following temperature ranges: 23°C ± 2°C, 25°C ± 5°C, or 20°C ± 5°C.

[0052] This application provides a calcium metal battery based on a highly conductive composite current collector, aiming to improve the cycle stability of the metal battery.

[0053] In some embodiments, the calcium metal battery includes a negative electrode sheet, a positive electrode sheet, an electrolyte, and a separator;

[0054] The negative electrode sheet includes a negative current collector, and the negative current collector includes a negative support layer, a negative metal layer provided on at least one surface of the negative support layer, and a negative ion transport layer provided on the surface of the negative metal layer facing away from the negative support layer. The negative ion transport layer includes a conductive polymer C, a conductive agent C, and a binder C;

[0055] The positive electrode sheet includes a modified positive electrode material, and the modified positive electrode material includes a positive electrode material and a positive ion transport layer coating the positive electrode material. The positive ion transport layer includes a conductive polymer D.

[0056] In the calcium metal battery provided by the present application, the negative current collector in the negative electrode sheet includes a negative support layer, a negative metal layer, and a negative ion transport layer, which belongs to a composite current collector. Compared with a metal foil of the same thickness, it has the characteristics of lighter mass and easier improvement of the mass energy density of the battery cell. Among them, the negative ion transport layer includes a conductive polymer C, which contains a large number of conjugated π bonds and can effectively conduct electrons. During the calcium ion deposition process, the conjugated π bonds are enriched with a large number of electrons and exhibit electronegativity, which can accelerate the migration and transport of calcium ions through Coulomb attraction and provide abundant negative charges to promote the reduction reaction and uniform deposition of calcium ions. During the calcium ion stripping process, the conjugated π bonds lose electrons and exhibit electropositivity, which can accelerate the oxidation of calcium atoms to form calcium ions and promote the migration of calcium ions from the negative electrode to the electrolyte through Coulomb repulsion. At the same time, the positive electrode sheet includes a modified positive electrode material, which forms a positive ion transport layer by coating the conductive polymer D on the surface of the positive electrode material. On the one hand, it can promote the migration and diffusion of calcium ions and improve the kinetic performance. On the other hand, it has a protective effect on the positive electrode material, thereby improving the structural stability of the modified positive electrode material. Therefore, the calcium metal battery provided by the present application has excellent cycle stability. In some of its embodiments, it can still maintain more than 80% of its capacity after 370 charge-discharge cycles.

[0057] In the present application, the calcium metal battery, as a type of multivalent metal battery in secondary batteries, includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the charge and discharge process of the battery, calcium ions (Ca 2+ ), as active ions, shuttle between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuit between the positive and negative electrodes, and at the same time allows calcium ions to pass through.

[0058] The following are some descriptions of the negative electrode sheet of the calcium metal battery.

[0059] In some embodiments, as Figure 1 shown, the negative electrode sheet includes a negative current collector, and the negative current collector includes a negative support layer 11, a negative metal layer 12 disposed on two surfaces of the negative support layer 11, and a negative ion transport layer 13 disposed on the surface of the negative metal layer 12 facing away from the negative support layer 11.

[0060] In the present application, the negative support layer 11 has two surfaces opposite to each other in its own thickness direction, Figure 1 and the negative metal layer 12 in

[0061] In some embodiments, the negative electrode support layer 11 includes a polymer-based film 11a and a conductive agent A, and the conductive agent A is dispersed in the polymer-based film 11a.

[0062] Traditional composite current collectors use a polymer-based film as the support layer, which generally does not have good electrical conductivity and is prone to heat generation under high-rate current operating conditions, thereby deteriorating the electrochemical performance of the battery. The negative electrode support layer 11 provided in this application, by adding an appropriate amount of conductive agent A to the polymer-based film 11a, on the one hand, can improve the conductivity of the negative electrode support layer 11 and enhance its electrical conductivity, and on the other hand, the conductive agent A can also play a toughening role and improve the mechanical strength of the negative electrode support layer 11, enabling it to buffer stress and maintain structural stability during battery preparation and operation, thus providing guarantee for the performance of the battery.

[0063] In some embodiments, the material of the polymer-based film 11a includes one or more of polyethylene (PE), polypropylene (PP), polyimide (PI), polyvinyl chloride (PVC), polystyrene (PS), polyvinyl alcohol (PVA), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT), and further optionally one or more of polypropylene (PP), polyimide (PI), and polyethylene terephthalate (PET).

[0064] In some embodiments, the conductive agent A includes one or more of inorganic carbon materials and materials containing metal elements.

[0065] In some embodiments, the inorganic carbon materials include one or more of conductive carbon black, conductive graphite, acetylene black, Ketjen black, carbon quantum dots, carbon nanotubes (CNT), carbon nanofibers (CNF), graphene, and fullerenes. Among them, conductive carbon black can be selected from Super-P (SP), Super-C (SC), etc.

[0066] In some embodiments, the materials containing metal elements include one or more of copper (Cu), aluminum (Al), nickel (Ni), gold (Au), silver (Ag), and MXene materials.

[0067] In some embodiments, the molecular formula of the MXene material is M n+1 X n T x . Wherein, n = 1, 2, 3; M represents a transition metal element, and M includes one or more of Ti, Ta, Mo, V, Sr, and Zr; X represents one or more of carbon and nitrogen elements; T represents a surface active functional group, and T includes one or more of -OH, -F, and -O, and x represents the number of T, and x>0. As an example, the MXene material can be selected from Ti3C2T x 、Ti2CTx , Ti3CNT x , Ta4C3T x , V2CT x , V3C2T x , Mo2CT x or Mo2TiC2T x etc.

[0068] In some embodiments, the size of the conductive agent A is 20 nm to 400 nm, and for example, it can be 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm or 400 nm. If the conductive agent A is particulate matter, the size of the conductive agent A refers to the particle diameter of the particulate matter; if the conductive agent A is a one-dimensional material such as carbon nanotubes (CNT) or carbon nanofibers (CNF), the size of the conductive agent A refers to the diameter of the one-dimensional material.

[0069] In some embodiments, the mass ratio of the polymer-based film 11a to the conductive agent A is 100:(1 to 30), and for example, it can be 100:1, 100:2, 100:5, 100:10, 100:12, 100:15, 100:20, 100:25 or 100:30, and further preferably 100:(5 to 15).

[0070] In some embodiments, the polymer-based film 11a is further provided with a plurality of through holes, and the through holes are filled with a conductive composition 11b, and the conductive composition 11b includes a conductive polymer B, a conductive agent B and a binder B.

[0071] To improve the electrical conductivity of the polymer-based film, it has been reported that through holes are formed in the polymer-based film and conductive metal is deposited in the through holes to connect with the conductive layer on the surface of the polymer-based film, but this strategy will deteriorate the strength and toughness of the current collector. In this application, the through holes are filled with the conductive composition 11b containing the conductive polymer B, which can not only effectively improve the electrical conductivity of the negative electrode support layer 11, but also maintain excellent mechanical strength and high toughness. At the same time, the density of the conductive composition 11b is less than that of the conductive metal material, further ensuring the weight reduction effect of the negative electrode support layer 11.

[0072] In some embodiments, the aperture of the through hole is 10 μm to 100 μm, and for example, it can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm; the distance between two adjacent through holes is 500 μm to 4000 μm, and for example, it can be 500 μm, 1000 μm, 1500 μm, 2000 μm, 2500 μm, 3000 μm, 3500 μm or 4000 μm.

[0073] In the present application, the shape of the through-hole includes one or more of a circular shape, a square shape, a rhombus shape, an equilateral triangle shape, an hourglass shape, and an irregular shape. If the shape of the through-hole is circular, the aperture refers to the diameter of the circle; if the shape of the through-hole is square, rhombus or equilateral triangle, the aperture refers to the side length of the square, rhombus or equilateral triangle; if the shape of the through-hole is hourglass or irregular, the aperture refers to the equivalent circle diameter, that is, the diameter of a circle with the same planar projection area as the hole is used as the aperture of the through-hole. The distance between two adjacent through-holes refers to the shortest distance between the edges of two adjacent through-holes.

[0074] In some embodiments, the conductive polymer B includes one or more of polypyrrole (PPy), polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-hexylthiophene) (P3HT), poly(3-dodecylthiophene) (P3DDT), poly(3-dodecylthiophene-3-hexyl-3-triethylene glycol) (PDDHEO), and poly(3-octylpyrrole): poly(styrenesulfonic acid) (P3OPy:PSS).

[0075] The above-mentioned conductive polymer B is doped with anions, so that the conductive composition 11b has good electrical conductivity, which is beneficial to enhancing the electrical conductivity effect of the negative electrode support layer 11. At the same time, the conductive polymer B also has a certain positive temperature coefficient (PTC) effect. The conductive polymer B realizes the PTC effect based on the doping and dedoping mechanism of anions. At the high-temperature critical temperature, the dedoping of anions will occur, which will cause the disorder of the polymer main chain and lead to a sharp increase in the resistance value. This process does not involve the change of the conductive polymer main chain and has a certain reversibility. In addition, the introduction of the conductive agent B also promotes the doping and dedoping reactions of anions to a certain extent. Therefore, the conductive composition 11b of the present application has a very rapid response speed to temperature changes and strong reaction reversibility, so that the negative electrode support layer 11 has both excellent electrical conductivity and safety.

[0076] In some embodiments, the conductive agent B includes one or more of inorganic carbon materials and materials containing metal elements. Among them, the types of the inorganic carbon materials and the materials containing metal elements in the conductive agent B are basically the same as those of the conductive agent A, which will not be elaborated here. Further, the conductive agent B includes one or more of conductive carbon black (such as Super-P, Super-C, etc.), acetylene black, carbon nanotubes, and graphene.

[0077] In some embodiments, the particle size of the conductive agent B is 20 nm to 400 nm, and for example, it can be 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, or 400 nm.

[0078] In some embodiments, the binder B includes one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), hydrogenated nitrile butadiene rubber (HNBR), polyvinyl alcohol (PVA), polymethacrylic acid (PMAA), polymethyl methacrylate (PMMA), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), sodium alginate (SA), sodium carboxymethyl cellulose (CMC), and carboxymethyl chitosan (CMCS), and is further optionally PVDF.

[0079] In some embodiments, the mass ratio of the conductive polymer B, the conductive agent B, and the binder B is 100:(1 - 50):(1 - 15). As an example, the mass ratio of the conductive polymer B to the conductive agent B can be 100:1, 100:5, 100:10, 100:15, 100:20, 100:25, 100:30, 100:35, 100:40, 100:45, or 100:50, and the mass ratio of the conductive polymer B to the binder B can be 100:1, 100:2, 100:5, 100:8, 100:10, 100:12, 100:14, or 100:15.

[0080] In some embodiments, the thickness of the negative electrode support layer 11 is 4 μm to 8 μm, and can be, for example, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, or 8 μm.

[0081] In some embodiments, the method for preparing the negative electrode support layer 11 includes the following steps:

[0082] S110: Melt-blend the polymer resin and the conductive agent A, and perform a film-forming treatment on the obtained mixture, so that the polymer resin forms a polymer-based film 11a, and the conductive agent A is dispersed in the polymer-based film 11a;

[0083] S120: Prepare a plurality of through holes in the polymer-based film 11a by using a laser etching method or a die-cutting method;

[0084] S130: Fill the through holes with the conductive composition 11b to obtain the negative electrode support layer 11.

[0085] In some embodiments, the temperature of the melt-blending is 100°C to 450°C, and can be, for example, 100°C, 200°C, 250°C, 300°C, 350°C, 400°C, or 450°C; the time of the melt-blending is 0.5 h to 8 h, and can be, for example, 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, or 8 h.

[0086] In some embodiments, the method of film-forming treatment includes one or more of a compression molding method, a hot pressing method, an autoclave molding method, and a calendering method.

[0087] In some embodiments, the method for preparing the through holes includes a laser etching method and a die cutting method.

[0088] In some embodiments, filling the conductive composition 11b in the through holes includes the following steps: dissolving the conductive polymer B in a solvent to obtain a solution B; adding a conductive agent B and a binder B to the solution B, and ultrasonically dispersing for 0.5 h to 3 h to obtain a dispersion B; covering the area outside the through holes in the polymer base film 11a with a mask, filling the dispersion B in the through holes by a doctor blade method, and vacuum drying at 60 °C to 100 °C for 24 h to 48 h. Among them, the solvent of the solution B can be one or more of toluene and chloroform, and the mass fraction of the conductive polymer B in the solution B can be 1% to 5%.

[0089] In some embodiments, the material of the negative electrode metal layer 12 includes calcium (Ca), tin (Sn), calcium tin alloy (CaSn), calcium bismuth alloy (CaBi), or calcium antimony alloy (CaSb).

[0090] Thus, by using the above-mentioned metal or alloy for the negative electrode metal layer 12, it can not only play the function of conductive current collection, but also serve as the metal negative electrode of the calcium metal battery, which is beneficial to reducing the use of negative electrode materials and saving battery space.

[0091] In some embodiments, the thickness of the negative electrode metal layer 12 is 0.5 μm to 10 μm, for example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

[0092] In some embodiments, the negative electrode metal layer 12 can be prepared by a magnetron sputtering method. Specifically, the preparation method of the negative electrode metal layer 12 includes the following steps: evacuating to ≤(2 - 8)×10 -5 Pa, introducing an inert gas at a flow rate of 50 sccm to 100 sccm, and performing DC magnetron sputtering coating under the conditions that the sputtering pressure is 0.5 Pa to 5 Pa and the sputtering power is 100 W to 300 W to form the negative electrode metal layer 12 on the surface of the negative electrode support layer 11. Among them, the inert gas includes one or more of helium, neon, argon, krypton, and xenon.

[0093] In some embodiments, the negative electrode ion transport layer 13 includes a conductive polymer C, a conductive agent C, and a binder C.

[0094] In some embodiments, the conductive polymer C includes one or more of polypyrrole (PPy), polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-hexylthiophene) (P3HT), poly(3-dodecylthiophene) (P3DDT), poly(3-dodecylthiophene-3-hexyl-3-triethylene glycol) (PDDHEO), and poly(3-octylpyrrole):poly(styrenesulfonic acid) (P3OPy:PSS).

[0095] Different from traditional polymer materials, the conductive polymer C contains a large number of conjugated π bonds, also known as conjugated polymers, which have good electron conduction. During the Ca 2+ deposition process, the conjugated π bonds enrich a large number of electrons and exhibit electronegativity, which can accelerate the migration and diffusion of Ca 2+ through Coulomb attraction, and provide abundant negative charges to promote the reduction reaction and uniform deposition of calcium ions. During the Ca 2+ stripping process, the conjugated π bonds lose electrons and exhibit electropositivity, which can accelerate the oxidation of atoms to form calcium ions, and promote the migration of Ca 2+ from the negative electrode to the electrolyte through Coulomb repulsion. Thus, by setting the negative electrode ion transport layer 13 with the conductive polymer C, the transport kinetics of Ca 2+ is effectively improved, thereby improving the cycle stability of the battery.

[0096] In some embodiments, the conductive agent C includes one or more of inorganic carbon materials and materials containing metal elements. Among them, the types of the inorganic carbon materials and the materials containing metal elements in the conductive agent C are basically the same as those of the conductive agent A, which will not be elaborated here. Further, the conductive agent C includes one or more of conductive carbon black (such as Super-P, Super-C, etc.), acetylene black, carbon nanotubes, and graphene.

[0097] In some embodiments, the particle size of the conductive agent C is 20 nm to 400 nm, and for example, it can be 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, or 400 nm.

[0098] In some embodiments, the binder C includes one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), hydrogenated nitrile rubber (HNBR), polyvinyl alcohol (PVA), polymethacrylic acid (PMAA), polymethyl methacrylate (PMMA), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), sodium alginate (SA), sodium carboxymethyl cellulose (CMC), and carboxymethyl chitosan (CMCS), and further preferably PVDF.

[0099] In some embodiments, the mass ratio of the conductive polymer C, the conductive agent C, and the binder C is 100:(1 to 50):(1 to 15). As an example, the mass ratio of the conductive polymer C to the conductive agent C can be 100:1, 100:5, 100:10, 100:15, 100:20, 100:25, 100:30, 100:35, 100:40, 100:45, or 100:50, and the mass ratio of the conductive polymer C to the binder C can be 100:1, 100:2, 100:5, 100:8, 100:10, 100:12, 100:14, or 100:15.

[0100] In some embodiments, the thickness of the negative ion transport layer 13 is 0.5 μm to 2 μm, and for example, it can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, or 2 μm.

[0101] In some embodiments, the method for preparing the negative ion transport layer 13 includes the following steps: dissolving the conductive polymer C in a solvent to obtain a solution C; adding the binder C to the solution C and ultrasonically dispersing for 0.5 h to 3 h to obtain a dispersion C; coating the dispersion C on the surface of the negative electrode metal layer 12 and vacuum drying at 60°C to 100°C for 24 h to 48 h to obtain the negative ion transport layer 13. Among them, the solvent of the solution C can be one or more of toluene and chloroform, and the mass fraction of the conductive polymer C in the solution C can be 1% to 5%.

[0102] The following are some descriptions of the positive electrode plate of the calcium metal battery.

[0103] In some embodiments, as Figure 2 shown, the positive electrode plate includes a positive current collector, and the positive current collector includes a positive support layer 21 and positive metal layers 22 provided on two surfaces of the positive support layer 21.

[0104] In the present application, the structure, material, and preparation method of the positive support layer 21 are basically the same as those of the negative support layer 11. For example, a conductive agent A is dispersed in the polymer-based film, the polymer-based film is provided with a plurality of through holes, and the through holes are filled with a conductive composition, etc., which will not be elaborated in the present application. The positive support layer 21 has two surfaces opposite to each other in its own thickness direction, Figure 2 and the positive metal layers 22 in

[0105] are provided on two opposite surfaces of the positive support layer 21. However, the present application is not limited thereto. In some other examples, the positive metal layer 22 can also be provided on any one surface of the positive support layer 21.

[0106] In some embodiments, the thickness of the positive electrode metal layer 22 is 0.5 μm to 10 μm, and for example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0107] In some embodiments, the positive electrode metal layer 22 can be prepared by magnetron sputtering, and its process conditions are basically the same as those of the negative electrode metal layer 12, which will not be elaborated in this application.

[0108] In some embodiments, the positive electrode sheet further includes a positive electrode active layer 23. As Figure 2 shown, the positive electrode active layer 23 is disposed on two surfaces of the positive electrode current collector, but this application is not limited thereto. In some other examples, the positive electrode active layer 23 can also be disposed on any one surface of the positive electrode current collector.

[0109] In some embodiments, the positive electrode active layer 23 includes a modified positive electrode material, and the modified positive electrode material includes a positive electrode material and a positive electrode ion transport layer coating the positive electrode material. The positive electrode ion transport layer includes a conductive polymer D.

[0110] In some embodiments, the positive electrode material includes one or more of prussian blue compounds, transition metal oxides, transition metal sulfides, and spinel compounds.

[0111] As an example, the expression of the prussian blue compound is A x MFe(CN)6∙yH2O. Wherein, A can be selected from Li, Na, Mg, Ca, etc., M can be selected from Ba, Ti, Mn, Fe, Co, Ni, etc., x≥0, y≥0, for example, Na x MnFe(CN)6, K2BaFe(CN)6, CaCoFe(CN)6, etc.

[0112] As an example, the transition metal oxides include one or more of vanadium oxides, molybdenum trioxide (MoO3), and manganese dioxide (MnO2). Among them, the vanadium oxides include vanadium pentoxide (V2O5) with a layered structure and layered vanadium oxides with ion pre-insertion layers, such as CaV6O 16 ·2.8H2O with calcium ion pre-insertion layer, double-layer Mg 0.25 V2O5·H2O with magnesium ion pre-insertion layer, Zn 0.25 V2O5·nH2O, etc.

[0113] As an example, the transition metal sulfide can be selected from titanium sulfide (TiS2), etc.

[0114] As an example, the expression of the spinel-type compound is A′M′2O4. Among them, A′ can be selected from Li, Na, Mg, Ca, etc., and M′ can be selected from Ti, V, Cr, Mn, Fe, Co, Ni, etc., such as CaCo2O4, etc.

[0115] In some embodiments, the conductive polymer D includes one or more of polypyrrole (PPy), polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-hexylthiophene) (P3HT), poly(3-dodecylthiophene) (P3DDT), poly(3-dodecylthiophene-3-hexyl-3-triethylene glycol) (PDDHEO), and poly(3-octylpyrrole):poly(styrenesulfonic acid) (P3OPy:PSS).

[0116] The use of the conductive polymer D to form a positive electrode ion transport layer on the surface of the positive electrode material can also promote the migration and diffusion of Ca 2+ , improving the kinetic performance of the modified positive electrode material. At the same time, the coating of the positive electrode ion transport layer also plays a good protective role for the inner core positive electrode material, effectively preventing the dissolution of transition metal elements, thereby ensuring the structural stability of the modified positive electrode material. Therefore, the cycle stability of the battery is improved.

[0117] In some embodiments, the mass ratio of the positive electrode material to the conductive polymer D is 2:(0.8~1.2), for example, it can be 2:0.8, 2:0.9, 2:1, 2:1.1, or 2:1.2, etc.

[0118] In some embodiments, the preparation method of the modified positive electrode material includes an in-situ polymerization encapsulation method. Specifically, the preparation method of the modified positive electrode material includes the following steps: mixing the positive electrode material, the monomer of the conductive polymer D, and a solvent, adding an oxidant, and carrying out an in-situ polymerization reaction at 20°C to 40°C for 12h to 48h; centrifuging the reaction mixture, washing the obtained solid product with deionized water and absolute ethanol, and drying it at 40°C to 80°C for 12h to 48h to obtain the modified positive electrode material.

[0119] In some embodiments, the oxidant includes one or more of ferric chloride (FeCl3), ammonium persulfate ((NH4)2S2O8), hydrogen peroxide (H2O2), and potassium chromate (K2CrO4).

[0120] In some embodiments, the molar ratio of the monomer of the conductive polymer D to the oxidant is 1:(1~2).

[0121] In some embodiments, the positive electrode active layer 23 further includes a positive electrode conductive agent and a positive electrode binder, and the mass ratio of the modified positive electrode material, the positive electrode conductive agent, and the positive electrode binder is (60-90):(5-25):(5-15), and further optionally 70:20:10. Among them, the positive electrode binder includes one or more of polyvinylidene fluoride (PVDF), sodium alginate (SA), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), hydrogenated nitrile rubber (HNBR), polytetrafluoroethylene (PTFE), and polyacrylic acid (PAA), and further optionally PVDF. The positive electrode conductive agent includes one or more of conductive carbon black, conductive graphite, acetylene black, Ketjen black, carbon quantum dots, carbon nanotubes, graphene, and carbon nanofibers, and further optionally acetylene black.

[0122] In some embodiments, the method for preparing the positive electrode sheet includes the following steps: dispersing the modified positive electrode material, the positive electrode conductive agent, and the positive electrode binder in a solvent (such as NMP), and obtaining a positive electrode slurry after homogenization; covering the positive electrode slurry on at least one surface of the positive electrode current collector, and obtaining the positive electrode sheet after drying, rolling, and cutting treatments.

[0123] The following are some descriptions of the separator of the calcium metal battery.

[0124] In some embodiments, as Figure 3 shown, the separator includes a base film 31 and a MOF coating 32 provided on two surfaces of the base film 31, and the MOF coating 32 includes a silane-modified calcium-based MOF material.

[0125] The electrolyte of the calcium metal battery usually uses calcium salts such as calcium hexafluorophosphate (Ca(PF6)2), and the HF generated by its hydrolysis will damage the solid electrolyte interface (SEI) film and the chemical-electrochemical interface (CEI) film formed on the surface of the positive electrode material, and then etch the positive electrode material, resulting in the dissolution of transition metal elements and the corrosion of the negative metal layer 12, etc. This causes a sharp decline in electrochemical performance.

[0126] In the MOF coating 32 provided in this application, the porous structure, organic ligands, and functional groups formed by surface modification of the silane-modified calcium-based MOF material (which can be denoted as modified Ca-MOF) can achieve effective adsorption of trace water, gases (such as O2, CO2, etc.), and HF. At the same time, the modified Ca-MOF has a large number of Ca active sites, which can enhance the migration ability of Ca 2+ at the separator, and further improve the kinetic performance of the battery.

[0127] In the present application, the substrate membrane 31 has two surfaces opposite to each other in its own thickness direction. Figure 3 The MOF coating 32 in

[0128] is disposed on the two opposite surfaces of the substrate membrane 31. However, the present application is not limited thereto. In some other examples, the MOF coating 32 may also be disposed on any one surface of the substrate membrane 31.

[0129] In some embodiments, the substrate membrane 31 may be a porous thin film having good chemical stability and mechanical stability. At the same time, the substrate membrane 31 may be a single-layer thin film or a multi-layer composite thin film. When the substrate membrane 31 is a multi-layer composite thin film, the materials of each layer may be the same or different, without particular limitation.

[0130] In some embodiments, the thickness of the substrate membrane 31 is 8 μm to 20 μm, and may be, for example, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm or 20 μm.

[0131] In some embodiments, in the silane-modified calcium-based MOF material, the organic ligand of the calcium-based MOF material includes one or more of 2-aminoterephthalic acid and 2,3-diaminoterephthalic acid.

[0132] In some embodiments, in the silane-modified calcium-based MOF material, the silane includes one or more of (3-glycidoxypropyl)trimethoxysilane (GPTMS), (3-glycidoxypropyl)triethoxysilane and (3-glycidoxypropyl)dimethoxysilane.

[0133] In some embodiments, in the silane-modified calcium-based MOF material, the molar ratio of the calcium-based MOF material to the silane is 1:(1 to 15), and may be, for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15, and is further preferably 1:(6 to 12).

[0134] In some embodiments, the preparation method of the calcium-based MOF material includes the following steps: mixing a calcium salt, an organic ligand and a solvent, adding a structure regulator, performing ultrasonic dispersion, and then carrying out a solvothermal reaction at 100°C to 150°C for 12 h to 48 h; centrifuging the reaction mixture, washing the obtained solid product with DMF, and drying at 80°C to 100°C for 4 h to 8 h to obtain the calcium-based MOF material. Among them, the structure regulator can be used to control the growth size, pore size and crystal morphology of the MOF.

[0135] In some embodiments, the calcium salt includes one or more of calcium chloride (CaCl2), calcium nitrate (Ca(NO3)2), calcium sulfate (CaSO4), and calcium oxalate (CaC2O4). Understandably, the calcium salt may or may not contain crystal water, such as CaCl2·2H2O and CaSO4·2H2O, etc.

[0136] In some embodiments, the molar ratio of the calcium salt to the organic ligand is (1~1.5):1, for example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1.

[0137] In some embodiments, the structure regulator includes one or more of benzoic acid, formic acid, and acetic acid.

[0138] In some embodiments, the ratio of the mass of the structure regulator to the total mass of the calcium salt and the organic ligand is (10~15):1.

[0139] In some embodiments, the method for preparing the silane-modified calcium-based MOF material includes the following steps: in a protective atmosphere, mixing the calcium-based MOF material and a solvent, adding silane, and carrying out a grafting reaction at 100°C~150°C for 12h~48h; centrifuging the reaction mixture, washing the obtained solid product with DMF, and drying it at 60°C~80°C for 6h~18h to obtain the silane-modified calcium-based MOF material.

[0140] Thus, during the grafting reaction, the amino group (derived from the organic ligand) on the calcium-based MOF material undergoes a ring-opening reaction with the epoxy group in the silane, so that the silane is grafted onto the calcium-based MOF material.

[0141] In some embodiments, the MOF coating 32 further includes a binder E, and the mass ratio of the silane-modified calcium-based MOF material to the binder E is (90~95):(5~10). The binder E includes one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), hydrogenated nitrile rubber (HNBR), polyvinyl alcohol (PVA), polymethacrylic acid (PMAA), polymethyl methacrylate (PMMA), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), sodium alginate (SA), sodium carboxymethyl cellulose (CMC), and carboxymethyl chitosan (CMCS), and further preferably PVDF.

[0142] In some embodiments, the thickness of the MOF coating 32 is 0.5μm~2μm, for example, it can be 0.5μm, 0.8μm, 1μm, 1.2μm, 1.5μm, 1.8μm, or 2μm.

[0143] In some embodiments, the method for preparing the MOF coating 32 includes the following steps: dispersing the silane-modified calcium-based MOF material and the binder E in a solvent (such as DMF) to obtain a MOF slurry; covering the MOF slurry on at least one surface of the substrate membrane 31, and drying it in vacuum at 60°C to 80°C for 6h to 18h to obtain the MOF coating 32.

[0144] The following are some descriptions of the electrolyte of the calcium metal battery.

[0145] It can be understood that the electrolyte in the calcium metal battery can be liquid, gel-like or all-solid-state.

[0146] In some embodiments, the electrolyte of the calcium metal battery uses an electrolyte solution, which includes a calcium salt, an organic solvent, and an additive.

[0147] In some embodiments, the calcium salt includes one or more of calcium hexafluorophosphate (Ca(PF6)2), calcium tetrafluoroborate (Ca(BF4)2), calcium borohydride (Ca(BH4)2), calcium perchlorate (Ca(ClO4)2), calcium bis(trifluoromethanesulfonyl)imide (Ca(TFSI)2), and calcium trifluoromethanesulfonate (Ca(CF3SO3)2).

[0148] In some embodiments, the concentration of the calcium salt in the electrolyte solution is 0.1 mol / L to 10 mol / L, and for example, it can be 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, or 10 mol / L.

[0149] In some embodiments, the organic solvent includes one or more of ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (MEC), diethyl carbonate (DEC), methyl butyrate (MB), ethyl propionate, methyl propionate, propylene carbonate (PC), γ-butyrolactone (γ-BL), acetonitrile (AN), ethyl acetate (EA), methyl acetate (MA), propyl formate (PF), methyl formate (MF), tetrahydrofuran (THF), toluene, and xylene.

[0150] In some embodiments, the additive includes one or more of trimethoxyphenylsilane (TMPS) and 2-cyano-3-fluoropyridine-5-boronic acid pinacol ester (FTDP).

[0151] TMPS and FTDP have excellent HF capture ability, can effectively improve the erosion problem of HF on the positive and negative electrodes, and enhance the cycle stability of the battery.

[0152] In some embodiments, the mass fraction of trimethoxyphenylsilane (TMPS) in the electrolyte is 0.1% to 5%, for example, it can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0153] In some embodiments, the mass fraction of 2-cyano-3-fluoropyridine-5-boronic acid pinacol ester (FTDP) in the electrolyte is 0.1% to 1%, for example, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%.

[0154] The following is other descriptions of the calcium metal battery.

[0155] In some embodiments, the positive electrode sheet, the negative electrode sheet and the separator are made into an electrode assembly by a winding process or a stacking process.

[0156] In some embodiments, the calcium metal battery further includes an outer package for encapsulating the above-mentioned electrode assembly and electrolyte. The outer package of the calcium metal battery includes one or more of a hard shell and a soft package. Among them, the hard shell can be a hard plastic shell, an aluminum shell, a steel shell, etc., and the soft package can be a bag-type soft package or a plastic soft package.

[0157] The present application also provides a battery module, which includes a housing and a plurality of calcium metal batteries arranged inside the housing. In the battery module, the plurality of calcium metal batteries can be arranged in sequence along the length direction of the battery module, and the number of calcium metal batteries can be determined according to the application and capacity of the battery module.

[0158] The present application also provides a battery pack, which includes a battery box and a plurality of battery modules arranged inside the battery box. In the battery pack, the plurality of battery modules can be arranged in the battery box in any manner, and the number of battery modules can be determined according to the application and capacity of the battery pack.

[0159] The present application also provides an electrical device, which includes the calcium metal battery as described above. The calcium metal battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device. The electrical device can include mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto. Among them, the mobile device can be, for example, a mobile phone, a laptop computer, etc.; the electric vehicle can be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited thereto.

[0160] The following is a further description in combination with specific examples and comparative examples. The raw materials involved in the following specific examples and comparative examples can be commercially available without special instructions. The instruments used can be commercially available without special instructions. The processes involved, without special instructions, are the conventional choices of those skilled in the art.

[0161] Example 1

[0162] The calcium metal battery of this example was prepared by the following method:

[0163] (1) Preparation of the positive electrode sheet:

[0164] The polymer resin PET and the conductive agent CNF (with a diameter of 50 nm and a length of 1 µm) were mixed at a mass ratio of 100:14, and then melt-blended at 300 °C for 2 h. After mixing evenly, they were molded by pressing. The polymer resin formed a polymer-based film, and the conductive agent was dispersed in the polymer-based film. Subsequently, by using the method of laser etching, circular through-holes with a pore diameter of 60 µm and a pitch of 3000 µm were prepared in the polymer-based film.

[0165] Poly(3-dodecylthiophene) (P3DDT) was dissolved in toluene to obtain P3DDT with a mass fraction of 3% of P3DDT. The conductive agent SP and the binder PVDF were added to the P3DDT, and the mass ratio of P3DDT, SP, and PVDF was 100:30:10. After ultrasonic dispersion for 2.5 h, a dispersion was obtained. The area outside the circular through-holes in the polymer-based film was covered with a mask plate, and the dispersion was filled into the circular through-holes by using the doctor blade method. Subsequently, it was vacuum-dried at 70 °C for 36 h to obtain a 6-μm-thick positive electrode support layer.

[0166] The positive electrode support layer was transferred into the cavity of a magnetron sputtering device, and the vacuum was pumped to 5×10 -5 Pa. Argon was introduced at a flow rate of 80 sccm, and DC magnetron sputtering coating was carried out under the conditions of a working pressure of 2 Pa and a working power of 150 W. A 1-μm-thick Al layer was formed on both surfaces of the positive electrode support layer as the positive electrode metal layer to obtain the positive electrode current collector.

[0167] The positive electrode material CaV6O 16 ·2.8H2O (CVO) and the monomer pyrrole (Py) of the conductive polymer D were dispersed in deionized water at a mass ratio of 2:1.1. Oxidant FeCl3 was added (the molar ratio of pyrrole to FeCl3 was 9:11), and then in-situ polymerization reaction was carried out at room temperature for 24 h. After centrifugation, the obtained solid product was washed clean with deionized water and ethanol, and dried at 60 °C for 24 h to obtain the modified positive electrode material (i.e., CaV6O 16 ·2.8H2O coated with PPy).

[0168] Mix the modified cathode material, conductive agent acetylene black, and binder PVDF evenly at a mass ratio of 70:20:10, add NMP for homogenization to obtain the cathode slurry; coat the cathode slurry on both surfaces of the cathode current collector, and after drying, rolling, and cutting, obtain the cathode electrode sheet.

[0169] (2)Preparation of the anode electrode sheet:

[0170] After mixing the polymer resin PP and the conductive agent CNF (with a diameter of 50 nm and a length of 1 µm) at a mass ratio of 100:14, perform melt blending at 220 °C for 4 h. After mixing evenly, perform compression molding, and the polymer resin forms a polymer-based film, and the conductive agent is dispersed in the polymer-based film. Using the method of laser etching, circular through-holes with a pore diameter of 60 µm and a pitch of 3000 µm are prepared in the polymer-based film. Subsequently, refer to the method in step (1) to fill the circular through-holes with the conductive composition to obtain a 4.5-μm-thick anode support layer.

[0171] Transfer the anode support layer to the chamber of a magnetron sputtering device, evacuate to 5×10 -5 Pa, introduce argon at a flow rate of 60 sccm, and perform DC magnetron sputtering coating under the conditions of a working pressure of 3 Pa and a working power of 250 W to form a 6-μm-thick CaSn alloy layer on both surfaces of the anode support layer as the anode metal layer.

[0172] Dissolve poly(3-dodecylthiophene) (P3DDT) in toluene to obtain P3DDT with a P3DDT mass fraction of 3%; add the conductive agent SP and the binder PVDF to P3DDT, and the mass ratio of P3DDT, SP, and PVDF is 100:30:10. Perform ultrasonic dispersion for 2.5 h to obtain a dispersion; coat the dispersion on the surface of the anode metal layer, and after vacuum drying at 70 °C for 36 h, form a 1-μm-thick anode ion transport layer to obtain the anode current collector, which is used as the anode electrode sheet.

[0173] (3)Preparation of the electrolyte:

[0174] Mix EC, DMC, and EMC in a volume ratio of 4:3:2 to form an organic solvent, dissolve Ca(PF6)2 in the organic solvent, and the concentration of Ca(PF6)2 is 0.7 mol / L. Subsequently, add 2-cyano-3-fluoropyridine-5-boronic acid pinacol ester (FTDP) with a mass fraction of 0.2% to obtain the electrolyte.

[0175] (4)Preparation of the separator:

[0176] CaCl2 and 2-aminoterephthalic acid were dissolved in DMF at a molar ratio of 1.16:1. Subsequently, benzoic acid (12 times the total mass of CaCl2 and 2-aminoterephthalic acid) was added. After ultrasonic dispersion, the solvothermal reaction was carried out at 120 °C for 24 h. After centrifugation, the obtained solid was washed with DMF and dried at 85 °C for 6 h to obtain a calcium-based MOF material (denoted as Ca-MOF).

[0177] Under N2 atmosphere, Ca-MOF was dispersed in DMF, and then (3-glycidyloxypropyl)trimethoxysilane (GPTMS) was added. The molar ratio of Ca-MOF to GPTMS was 1:6. The reaction was carried out at 110 °C for 12 h. Through the ring-opening reaction between the amino group of Ca-MOF and the epoxy group of GPTMS, GPTMS was grafted onto Ca-MOF. After the reaction, centrifugation was carried out to obtain a pale yellow precipitate, which was dried under vacuum at 70 °C for 12 h to obtain silane-modified Ca-MOF.

[0178] The silane-modified Ca-MOF and the binder PVDF were dispersed in DMF at a mass ratio of 95:5 to obtain a MOF slurry; the MOF slurry was coated on both surfaces of a 12-µm-thick PE substrate film and dried in a vacuum oven at 70 °C for 24 h to form a 1-µm-thick MOF coating.

[0179] (5) Preparation of calcium metal battery:

[0180] In a glove box (Ar atmosphere, water and O2 content < 0.1 ppm), the positive electrode plate, separator, and negative electrode plate were encapsulated with an aluminum-plastic film, dried to remove water, then the electrolyte was injected, and then sealed. After standing, hot and cold pressing, forming, clamping, capacity grading and other processes, a calcium metal battery was obtained.

[0181] Examples 2 to 6

[0182] Please refer to Table 1. Examples 2 to 6 are basically the same as Example 1, and the differences are as follows:

[0183] Example 2: In the modified positive electrode material, the positive ion transport layer uses P3DDT.

[0184] Example 3: In the negative electrode current collector, the material of the negative electrode metal layer is Ca.

[0185] Example 4: In the electrolyte, the additive is trimethoxyphenylsilane (TMPS) with a mass fraction of 1%.

[0186] Example 5: No additive was added to the electrolyte.

[0187] Example 6: The separator uses a 12-µm-thick PE substrate film, and no MOF coating is provided.

[0188] Comparative Examples 1 - 4

[0189] Please refer to Table 1. Comparative Examples 1 - 4 are basically the same as Example 1, with the differences being as follows:

[0190] Comparative Example 1: ① The positive electrode support layer uses a PET film, the negative electrode support layer uses a PP film, no conductive agent is added, and no through - hole structure is set; ② CVO is used as the positive electrode material, and no positive electrode ion - transport layer is coated; ③ No negative electrode ion - transport layer is set in the negative electrode current collector; ④ No additive is added to the electrolyte; ⑤ The separator membrane has no MOF coating.

[0191] Comparative Example 2: ① CVO is used as the positive electrode material, and no positive electrode ion - transport layer is coated; ② No negative electrode ion - transport layer is set in the negative electrode current collector; ③ No additive is added to the electrolyte; ④ The separator membrane has no MOF coating.

[0192] Comparative Example 3: ① CVO is used as the positive electrode material and is not coated; ② No additive is added to the electrolyte; ③ The separator membrane has no MOF coating.

[0193] Comparative Example 4: ① No negative electrode ion - transport layer is set in the negative electrode current collector; ② No additive is added to the electrolyte; ③ The separator membrane has no MOF coating.

[0194] The differences between Examples 1 - 6 and Comparative Examples 1 - 4 are shown in Table 1 as follows:

[0195] Table 1. Related parameters of calcium metal batteries

[0196]

[0197] Test Examples

[0198] The following tests are conducted on each example and each comparative example:

[0199] (1) Tensile strength: Cut three sample strips with a length and width of 150 mm×15 mm, ensure that the samples are vertically placed on the test clips of the tensile testing machine, detect after setting the parameters, and record the tensile strength.

[0200] (2) Peel strength: Attach the tape flatly to the steel plate, fix the sample to the tape, attach an auxiliary tape to the sample surface, and fix the steel plate and the auxiliary tape to the constant - speed tensile machine to start the test, and record the peel strength of each sample.

[0201] (3) Room - temperature cycle test: Conduct a room - temperature cycle test on the battery at 2C / 2C, and record the initial discharge specific capacity of the battery at 2C and the number of cycles when the capacity decays to 80%.

[0202] The above test results are shown in Table 2.

[0203] Table 2. Performance test results of calcium metal batteries

[0204]

[0205] As can be seen from Table 2, in Examples 1 to 6, the tensile strength of the positive current collector reaches 182 MPa, and the peel strength of the positive electrode sheet reaches 5.5 N / 25 mm; the tensile strength of the negative current collector reaches 166 MPa and the peel strength reaches 4.7 N / 25 mm, having the advantages of high tensile strength and high peel strength.

[0206] After assembling into batteries, the discharge specific capacities of the calcium metal batteries of Examples 1 to 6 at 2C are 102.2 mAh / g to 105.1 mAh / g, and the number of cycles for the capacity to decay to 80% is more than 370 times, which is significantly higher than the discharge specific capacities and the number of cycles of the calcium metal batteries of Comparative Examples 1 to 4, indicating that the calcium metal batteries of Examples 1 to 6 have the advantages of both high capacity and long cycle life.

[0207] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the various technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0208] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the protection scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A calcium metal battery based on a high-conductivity composite current collector, characterized in that: Including negative electrode sheet, positive electrode sheet, electrolyte and isolation membrane; The negative electrode sheet includes a negative electrode current collector, the negative electrode current collector includes a negative electrode support layer, a negative electrode metal layer disposed on at least one surface of the negative electrode support layer, and a negative electrode ion transport layer disposed on a surface of the negative electrode metal layer away from the negative electrode support layer, the negative electrode ion transport layer includes a conductive polymer C and a binder C; The positive electrode plate includes a modified positive electrode material, the modified positive electrode material includes a positive electrode material and a positive electrode ion transport layer covering the positive electrode material, and the positive electrode ion transport layer includes a conductive polymer D.

2. The calcium metal battery according to claim 1, characterized in that The negative electrode support layer comprises a polymer base film and a conductive agent A, wherein the conductive agent A is dispersed in the polymer base film; The polymer-based film is provided with a plurality of through holes, and the through holes are filled with a conductive composition, wherein the conductive composition includes a conductive polymer B, a conductive agent B and a binder B.

3. The calcium metal battery according to claim 2, characterized in that One or more of the following conditions are met: (1) The conductive polymer B, the conductive polymer C and the conductive polymer D each independently include one or more of polypyrrole, polyaniline, poly(3,4-ethylenedioxythiophene), poly(3-hexylthiophene), poly(3-dodecylthiophene), poly(3-dodecylthiophene-3-hexyl-3-triethylene glycol) and poly(3-octylpyrrole):poly(styrene sulfonic acid); (2) The conductive agent A and the conductive agent B each independently include one or more of an inorganic carbon material and a material containing a metal element; the inorganic carbon material includes one or more of conductive carbon black, conductive graphite, acetylene black, Ketjen black, carbon quantum dots, carbon nanotubes, carbon nanofibers, graphene and fullerene; the material containing a metal element includes one or more of copper, aluminum, nickel, gold, silver and MXene materials; (3) The binder B and the binder C each independently include one or more of polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, hydrogenated nitrile rubber, polyvinyl alcohol, polymethacrylic acid, polymethyl methacrylate, polyacrylic acid, sodium polyacrylate, polyacrylamide, sodium alginate, sodium carboxymethyl cellulose and carboxymethyl chitosan; (4) The material of the negative electrode metal layer includes calcium, tin, calcium-tin alloy, calcium-bismuth alloy or calcium-antimony alloy; (5) The mass ratio of the polymer base film to the conductive agent A is 100:(1-30); (6) The mass ratio of the conductive polymer B, the conductive agent B and the binder B is 100:(1-50):(1-15); (7) The mass ratio of the conductive polymer C to the binder C is 100:(1-15).

4. The calcium metal battery according to claim 2, characterized in that One or more of the following conditions are met: (1) The thickness of the negative electrode ion transport layer is 0.5 μm to 2 μm; (2) The thickness of the negative electrode metal layer is 0.5 μm to 10 μm; (3) The thickness of the negative electrode support layer is 4 μm to 8 μm; (4) The aperture of the through hole is 10 μm to 100 μm, and the distance between two adjacent through holes is 500 μm to 4000 μm.

5. The calcium metal battery according to any one of claims 1 to 4, characterized in that One or more of the following conditions are met: (1) The positive electrode material includes one or more of Prussian blue compounds, transition metal oxides, transition metal sulfides and spinel compounds; (2) The mass ratio of the positive electrode material to the conductive polymer D is 2: (0.8-1.2); (3) The preparation method of the modified positive electrode material includes an in-situ polymerization encapsulation method.

6. The calcium metal battery according to any one of claims 1 to 4, characterized in that The isolation film includes a base film and a MOF coating disposed on at least one surface of the base film, wherein the MOF coating includes a silane-modified calcium-based MOF material.

7. The calcium metal battery according to claim 6, characterized in that One or more of the following conditions are met: (1) The organic ligand of the calcium-based MOF material includes one or more of 2-aminoterephthalic acid and 2,3-diaminoterephthalic acid; (2) The silane includes one or more of (3-glycidyloxypropyl)trimethoxysilane, (3-glycidyloxypropyl)triethoxysilane and (3-glycidyloxypropyl)dimethoxysilane; (3) The molar ratio of the calcium-based MOF material to the silane is 1:(1-15); (4) The thickness of the MOF coating is 0.5 μm~2 μm.

8. The calcium metal battery according to any one of claims 1 to 4, characterized in that The electrolyte includes calcium salt, organic solvent and additives, and the additives include one or more of trimethoxyphenylsilane and 2-cyano-3-fluoropyridine-5-boric acid pinacol ester.

9. The calcium metal battery according to claim 8, characterized in that One or more of the following conditions are met: (1) The calcium salt includes one or more of calcium hexafluorophosphate, calcium tetrafluoroborate, calcium borohydride, calcium perchlorate, calcium bis(trifluoromethanesulfonyl imide) and calcium trifluoromethanesulfonate; (2) The concentration of the calcium salt in the electrolyte is 0.1 mol / L to 10 mol / L; (3) The organic solvent includes one or more of ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl butyrate, ethyl propionate, methyl propionate, propylene carbonate, γ-butyrolactone, acetonitrile, ethyl acetate, propyl formate, methyl formate, methyl acetate, tetrahydrofuran, toluene and xylene; (4) The mass fraction of the trimethoxyphenylsilane in the electrolyte is 0.1% to 5%; (5) The mass fraction of the 2-cyano-3-fluoropyridine-5-boronic acid pinacol ester in the electrolyte is 0.1% to 1%.

10. An electrical device, characterized in that: A calcium metal battery comprising the calcium metal battery according to any one of claims 1 to 9.

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