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

Abstract

The application relates to the technical field of secondary batteries, in particular to a calcium metal battery based on a high-conductivity composite current collector and a power utilization device. The calcium metal battery comprises a negative electrode sheet, a positive electrode sheet, an electrolyte and a separator film; the negative electrode sheet comprises a negative electrode current collector, the negative electrode current collector comprises a negative electrode support layer, a negative electrode metal layer arranged on at least one surface of the negative electrode support layer and a negative electrode ion transmission layer arranged on the surface of the negative electrode metal layer away from the negative electrode support layer, the negative electrode ion transmission layer comprises a conductive polymer C and a binder C; the positive electrode sheet comprises a modified positive electrode material, the modified positive electrode material comprises a positive electrode material and a positive electrode ion transmission layer coated on the positive electrode material, and the positive electrode ion transmission layer comprises a conductive polymer D. The calcium metal battery provided by the application has excellent cycle stability and can still maintain a capacity of more than 80% after 370 charge-discharge cycles.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of secondary batteries, in particular to a calcium metal battery based on a high-conductivity composite current collector and a power utilization device. BACKGROUND

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

[0003] In multivalent metal batteries, calcium metal batteries have the following characteristics: (1) calcium has a high abundance in the earth's crust, ranking fifth, which is 2500 times higher than that of lithium; (2) the volume specific capacity of the calcium negative electrode is 2072 mAh / mL, the mass specific capacity is 1337 mAh / g, and the standard reduction potential (2.87 V vs. SHE) is the closest to that of lithium (3.04 V vs. SHE); (3) compared with other multivalent metal ions, the large ionic radius of calcium ions leads to 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 the fields of large-scale power grids, energy storage systems and power batteries. However, the current calcium metal batteries have the problem of low cycle life. SUMMARY

[0004] Therefore, it is necessary to provide a calcium metal battery based on a high-conductivity composite current collector and a power utilization device to solve the problem of low cycle life of the calcium metal battery.

[0005] The above-mentioned purpose of the application is achieved by the following technical solutions:

[0006] In a first aspect, the application provides a calcium metal battery based on a high-conductivity composite current collector, which comprises a negative electrode sheet, a positive electrode sheet, an electrolyte and a separator.

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

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

[0009] In some embodiments, the negative electrode support layer comprises a polymer base film and a conductive agent A dispersed in the polymer base film;

[0010] The polymer base film is provided with a plurality of through holes filled with a conductive composition comprising a conductive polymer B, a conductive agent B, and a binder B.

[0011] In some embodiments, the conductive polymer B, the conductive polymer C, and the conductive polymer D each independently comprises 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).

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

[0013] In some embodiments, the binder B and the binder C each independently comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, butadiene-styrene 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 comprises calcium, tin, calcium-tin alloy, calcium-bismuth alloy, or calcium-antimony alloy.

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

[0016] 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).

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

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

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

[0020] In some embodiments, the thickness of the negative 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 spacing between two adjacent through holes is 500 μm to 4000 μm.

[0022] In some embodiments, the positive material comprises 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 material and the conductive polymer D is 2: (0.8-1.2).

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

[0025] In some embodiments, the separation film comprises a base film and a MOF coating layer disposed on at least one surface of the base film, and the MOF coating layer comprises a silane-modified calcium-based MOF material.

[0026] In some embodiments, the organic ligand of the calcium-based MOF material comprises one or more of 2-amino terephthalic acid and 2,3-diamino terephthalic acid.

[0027] In some embodiments, the silane comprises 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 and the silane is 1: (1-15).

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

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

[0031] In some embodiments, the calcium salt comprises one or more of calcium hexafluorophosphate, calcium tetrafluoroborate, calcium borohydride, calcium perchlorate, calcium bis-trifluoromethanesulfonimide, 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 comprises one or more of ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl butyrate, ethyl propionate, methyl propionate, propylene carbonate, gamma-butyrolactone, acetonitrile, ethyl acetate, propyl formate, methyl formate, methyl acetate, tetrahydrofuran, toluene, and xylene.

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

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

[0036] In a second aspect, the present application provides a power utilization device comprising 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 current collector in the negative electrode sheet comprises a negative support layer, a negative metal layer, and a negative ion transport layer, which is a kind of composite current collector. Compared with a metal foil with the same thickness, it has the characteristics of lighter mass, which helps to improve the mass energy density of the battery cell. The negative ion transport layer comprises a conductive polymer C, which contains a large number of conjugated π bonds and can effectively conduct electrons. During the deposition of calcium ions, the conjugated π bonds accumulate 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 stripping of calcium ions, 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 comprises a modified positive electrode material, which is coated with a conductive polymer D on the surface of the positive electrode material to form a positive ion transport layer. 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 can protect 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 embodiments, it can still maintain more than 80% of the capacity after 370 charge and discharge cycles. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, more completely understand the present application and its beneficial effects, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

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

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

[0042] Figure 3 Structure diagram of separator film in an embodiment of the present application.

[0043] Reference numerals: 11, negative support layer; 11a, polymer base film; 11b, conductive composition; 12, negative metal layer; 13, negative ion transport layer; 21, positive support layer; 22, positive metal layer; 23, positive active layer; 31, base film; 32, MOF coating. DETAILED DESCRIPTION

[0044] In order 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 realized 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 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 one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0046] In the present application, the meaning of "and / or" is any and all combinations of one or more of the associated listed items. The meaning of "at least one" is more than one, such as one, two, and more than two. The meaning of "a plurality of" or "several" is at least two, such as two, three, and the like, and the meaning of "a plurality of layers" is at least two layers, such as two layers, three layers, and the like, unless otherwise specifically limited. In the description of the present application, the meaning of "several" is at least one, such as one, two, and the like, unless otherwise specifically limited.

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

[0048] If not otherwise specified, all steps of the present application can be performed in sequence or randomly. For example, the method comprises steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c) means that step (c) can be added to the method in any sequence. For example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

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

[0050] In the present application, the temperature parameter, if not otherwise specified, allows for constant temperature treatment, and also allows for fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for fluctuations within the accuracy range controlled by the instrument. Fluctuations within a range of, for example, ±5℃, ±4℃, ±3℃, ±2℃, ±1℃ are allowed.

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

[0052] The present application provides a calcium metal battery based on a high-conductivity composite current collector, aiming to improve the cycle stability of the metal battery.

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

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

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

[0056] The calcium metal battery provided in the 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 transmission layer, which belongs to a composite current collector. Compared with a metal foil with the same thickness, it has the characteristics of lighter mass and easier improvement of the quality energy density of the battery cell. The negative electrode ion transmission layer includes a conductive polymer C, which contains a large number of conjugated π bonds and can effectively conduct electrons. In the process of calcium ion deposition, the conjugated π bond is rich in electrons and shows electronegativity, which can accelerate the migration and transmission of calcium ions through Coulomb attraction, and provide abundant negative charges to promote the reduction reaction and uniform deposition of calcium ions. In the process of calcium ion stripping, the conjugated π bond loses electrons and shows 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 is coated with a conductive polymer D on the surface of the positive electrode material to form a positive electrode ion transmission layer. 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 in the application has excellent cycle stability. In some embodiments, it can still maintain more than 80% capacity after 370 charge and discharge cycles.

[0057] In the application, the calcium metal battery as one of the multivalent metal batteries in the secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. In the process of charging and discharging of the battery, calcium ions (Ca 2+ ) as active ions move back and forth 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 arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuit of the positive and negative electrodes, and can also allow the calcium ions to pass through.

[0058] The following is a description 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 electrode current collector, and the negative electrode current collector includes a negative electrode support layer 11, a negative electrode metal layer 12 arranged on both surfaces of the negative electrode support layer 11, and a negative electrode ion transmission layer 13 arranged on the surface of the negative electrode metal layer 12 away from the negative electrode support layer 11.

[0060] In the application, the negative electrode support layer 11 has two opposite surfaces in the thickness direction of itself, Figure 1 The negative electrode metal layer 12 in the application is arranged on the two opposite surfaces of the negative electrode support layer 11. However, the application is not limited thereto, and in other examples, the negative electrode metal layer 12 can also be arranged on any one surface of the negative electrode support layer 11.

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

[0062] The conventional composite current collector uses a polymer base film as a support layer, which generally does not have good conductivity and is prone to heat generation under high-rate current working conditions, thereby degrading the electrochemical performance of the battery. The negative electrode support layer 11 provided in the present application adds an appropriate amount of conductive agent A to the polymer base film 11a, which can on the one hand improve the electrical conductivity of the negative electrode support layer 11 and enhance its 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, so as to buffer stress and maintain structural stability during battery preparation and working, thereby providing protection for the performance of the battery.

[0063] In some embodiments, the material of the polymer base film 11a comprises 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 is further optionally one or more of polypropylene (PP), polyimide (PI), and polyethylene terephthalate (PET).

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

[0065] In some embodiments, the inorganic carbon material comprises one or more of conductive carbon black, conductive graphite, acetylene black, Ketjen black, carbon quantum dots, carbon nanotubes (CNT), carbon nanofibers (CNF), graphene, and fullerene. The conductive carbon black can be selected from Super-P (SP), Super-C (SC), and the like.

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

[0067] In some embodiments, the MXene material has a molecular formula of M n+1 X n T x , wherein n = 1, 2, 3; M represents a transition metal element, M comprises one or more of Ti, Ta, Mo, V, Sr, and Zr; X represents one or more of carbon element and nitrogen element; T represents one or more of surface active functional groups, T comprises one or more of -OH, -F, and -O, and x represents the number of T, 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, for example, 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 a particulate, the size of the conductive agent A refers to the particle size of the particulate; if the conductive agent A is a one-dimensional material such as a carbon nanotube (CNT) or a carbon nanofiber (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: (1-30), for example, 100:1, 100:2, 100:5, 100:10, 100:12, 100:15, 100:20, 100:25, or 100:30, and further optionally 100: (5-15).

[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, which comprises the conductive polymer B, the conductive agent B, and the binder B.

[0071] To improve the conductivity of the polymer-based film, it has been reported that a through hole is formed in the polymer-based film, and a conductive metal is deposited in the through hole to connect with the conductive layer on the surface of the polymer-based film. However, this strategy deteriorates the strength and toughness of the current collector. In the present application, the conductive composition 11b containing the conductive polymer B is filled in the through hole, which not only effectively improves the conductivity of the negative electrode support layer 11, but also maintains 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, which further guarantees the weight reduction effect of the negative electrode support layer 11.

[0072] In some embodiments, the pore size of the through hole is 10 μm to 100 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm; and the spacing between two adjacent through holes is 500 μm to 4000 μm, for example, 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 circle, a square, a rhombus, an equilateral triangle, an hourglass shape, and an irregular shape. If the shape of the through hole is a circle, the hole diameter refers to the diameter of the circle; if the shape of the through hole is a square, a rhombus, or an equilateral triangle, the hole diameter refers to the side length of the square, rhombus, or equilateral triangle; if the shape of the through hole is an hourglass shape or an irregular shape, the hole diameter refers to the equivalent circle diameter, that is, the diameter of a circle with an area equivalent to the planar projection area of the hole is used as the hole diameter of the through hole. The spacing between two adjacent through holes refers to the shortest distance between the edges of the 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(styrene sulfonic acid) (P3OPy:PSS).

[0075] The conductive polymer B described above is doped with anions, so that the conductive composition 11b has good conductivity, which is conducive to enhancing the conductivity 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 a high-temperature critical temperature, dedoping of anions occurs, which causes the polymer main chain to be disordered and leads to a sharp rise in resistance. This process does not involve changes in 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 responds very quickly to temperature changes and has strong reaction reversibility, thereby making the negative electrode support layer 11 have excellent conductivity and safety.

[0076] In some embodiments, the conductive agent B includes one or more of inorganic carbon materials and metal element-containing materials. The types of inorganic carbon materials and metal element-containing materials in the conductive agent B are basically the same as those of the conductive agent A, which will not be described 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, for example, 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 comprises 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 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 and 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 and 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~8 μm, for example, can be 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 preparation method of the negative electrode support layer 11 comprises the following steps:

[0082] S110: melt-blending the polymer resin and the conductive agent A, and performing film forming treatment on the obtained mixture, so that the polymer resin forms a polymer base film 11a and the conductive agent A is dispersed in the polymer base film 11a;

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

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

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

[0086] In some embodiments, the method of film-forming treatment includes one or more of compression molding, heat compression molding, heat compression pot molding, and calender molding.

[0087] In some embodiments, the method of preparing the through hole includes laser etching and die cutting.

[0088] In some embodiments, the conductive composition 11b is filled in the through hole, including the following steps: dissolving the conductive polymer B in a solvent to obtain solution B; adding the conductive agent B and the binder B in the solution B, and ultrasonic dispersion for 0.5h-3h to obtain dispersion B; covering the area outside the through hole in the polymer-based film 11a with a mask, filling the dispersion B in the through hole by using the doctor blade method, and vacuum drying at 60°C-100°C for 24h-48h. 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%-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, the negative electrode metal layer 12 uses the above-mentioned metal or alloy, which 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 conducive 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 0.5μm-10μm, for example, it can be 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm.

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

[0093] In some embodiments, the negative 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(styrene sulfonic acid) (P3OPy:PSS).

[0095] Unlike traditional polymer materials, conductive polymer C contains a large number of conjugated π bonds, hence it is also known as a conjugated polymer, and has good electron conduction properties. In Ca... 2+ During deposition, conjugated π bonds accumulate a large number of electrons and become electronegative, which can accelerate the deposition of Ca through Coulomb attraction. 2+ The migration and diffusion of calcium ions provide abundant negative charges to promote the reduction reaction and uniform deposition of calcium ions. In Ca... 2+ During the stripping process, the conjugated π bond loses electrons and becomes electropositive, which can accelerate the oxidation of atoms to form calcium ions, and promote the formation of Ca ions through Coulomb repulsion. 2+ Migration from the negative electrode to the electrolyte. Therefore, by providing a negative electrode ion transport layer 13 with conductive polymer C, the migration of Ca is effectively enhanced. 2+ This improves the transport dynamics, thereby enhancing the cycle stability of the battery.

[0096] In some embodiments, conductive agent C includes one or more of inorganic carbon materials and materials containing metal elements. The types of inorganic carbon materials and materials containing metal elements in conductive agent C are basically the same as those in conductive agent A, and will not be repeated here. Further, 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 conductive agent C is 20nm~400nm, for example, it can be 20nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm or 400nm.

[0098] In some embodiments, the adhesive C comprises 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 may further be PVDF.

[0099] In some embodiments, the mass ratio of the conductive polymer C, the conductive agent C and the binder C is 100:(1~50):(1~15). For example, the mass ratio of the conductive polymer C and 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 and 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 anode ion transport layer 13 is 0.5 μm~2 μm, for example, 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 preparation method of the anode 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 in the solution C, ultrasonic dispersion for 0.5 h~3 h to obtain a dispersion liquid C; coating the dispersion liquid C on the surface of the anode metal layer 12, and vacuum drying at 60℃~100℃ for 24 h~48 h to obtain the anode ion transport layer 13. Wherein, the solvent of the solution C can be one or more of toluene, chloroform, and the mass fraction of the conductive polymer C in the solution C can be 1%~5%.

[0102] The following is a description of some of the positive electrode sheets of the calcium metal battery.

[0103] In some embodiments, as shown in Figure 2 , the positive electrode sheet includes a positive electrode current collector, and the positive electrode current collector includes a positive electrode support layer 21 and a positive electrode metal layer 22 arranged on both surfaces of the positive electrode support layer 21.

[0104] In this application, the structure, material and preparation method of the positive electrode support layer 21 are basically the same as those of the negative electrode support layer 11, for example, the 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 described here. The positive electrode support layer 21 has two opposite surfaces in the thickness direction of itself, Figure 2 The positive electrode metal layer 22 in the positive electrode support layer 21 is arranged on the opposite two surfaces of the positive electrode support layer 21. However, the application is not limited thereto, and in some other examples, the positive electrode metal layer 22 can also be arranged on any one surface of the positive electrode support layer 21.

[0105] In some embodiments, the material of the positive electrode metal layer 22 includes one or more of aluminum (Al) and stainless steel, and further optionally aluminum (Al).

[0106] In some embodiments, the thickness of the positive metal layer 22 is 0.5 μm to 10 μm, for example, 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 metal layer 22 can be prepared by a magnetron sputtering method, and the process conditions are basically consistent with those of the negative metal layer 12, which will not be described herein.

[0108] In some embodiments, the positive electrode sheet further comprises a positive active layer 23. As shown in FIG. 1, the positive active layer 23 is arranged on both surfaces of the positive current collector, but the present application is not limited thereto, and in some other examples, the positive active layer 23 can also be arranged on any one surface of the positive current collector. Figure 2

[0109] In some embodiments, the positive active layer 23 comprises a modified positive material, and the modified positive material comprises a positive material and a positive ion transport layer covering the positive material, and the positive ion transport layer comprises a conductive polymer D.

[0110] In some embodiments, the positive material comprises one or more of a Prussian blue compound, a transition metal oxide, a transition metal sulfide and a spinel compound.

[0111] For 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] For example, the transition metal oxide comprises one or more of a vanadium oxide compound, molybdenum trioxide (MoO3) and manganese dioxide (MnO2). Wherein the vanadium oxide compound comprises vanadium pentoxide (V2O5) with a layered structure and layered vanadium oxide with ion pre-intercalation, for example, CaV6O 16 ·2.8H2O with magnesium ion pre-intercalation, double-layer Mg 0.25 V2O5·H2O with zinc ion pre-intercalation, Zn 0.25 V2O5·nH2O, etc.

[0113] For example, the transition metal sulfide can be selected from titanium sulfide (TiS2) and the like.

[0114] ​As an example, the spinel compound has a formula of A'M'2O4. Wherein 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(styrene sulfonic acid) (P3OPy:PSS).

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

[0117] In some embodiments, the mass ratio of the cathode material and the conductive polymer D is 2: (0.8-1.2), which 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 cathode material includes an in-situ polymer encapsulation method. Specifically, the preparation method of the modified cathode material includes the following steps: mixing a cathode material, a monomer of a conductive polymer D, and a solvent, adding an oxidizing agent, and performing an in-situ polymerization reaction at 20-40°C for 12-48h; centrifuging the mixed solution after the reaction, washing the obtained solid product with deionized water and anhydrous ethanol, and drying at 40-80°C for 12-48h to obtain a modified cathode material.

[0119] In some embodiments, the oxidizing agent 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 and the oxidizing agent 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, wherein 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 more preferably 70:20:10. The positive electrode binder includes one or more of polyvinylidene fluoride (PVDF), sodium alginate (SA), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), hydrogenated nitrile butadiene rubber (HNBR), polytetrafluoroethylene (PTFE), and polyacrylic acid (PAA), and more preferably 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 more preferably 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), homogenizing them to obtain a positive electrode slurry; covering the positive electrode slurry on at least one surface of the positive electrode current collector, and then drying, rolling and cutting the slurry to obtain the positive electrode sheet.

[0123] The following is a description of the separator in calcium metal batteries.

[0124] In some embodiments, such as Figure 3 As shown, the isolation membrane includes a base membrane 31 and MOF coatings 32 disposed on two surfaces of the base membrane 31. The MOF coatings 32 include silane-modified calcium-based MOF materials.

[0125] The electrolyte in calcium metal batteries typically uses calcium salts such as calcium hexafluorophosphate (Ca(PF6)2). The HF produced by its hydrolysis damages the solid electrolyte interface (SEI) film and the chemical-electrochemical interface (CEI) film formed on the surface of the positive electrode material. This, in turn, etches the positive electrode material, leading to the dissolution of transition metal elements and corrosion of the negative electrode metal layer 12. Consequently, this results in a sharp decline in electrochemical performance.

[0126] The MOF coating 32 provided in this application utilizes the porous structure of the silane-modified calcium-based MOF material (which can be referred to as modified Ca-MOF), the organic ligands, and the functional groups formed by surface modification to achieve effective adsorption of trace amounts of water, gases (such as O2, CO2, etc.), and HF. Simultaneously, the modified Ca-MOF possesses a large number of Ca active sites, which can enhance the adsorption of Ca... 2+ The migration capability at the separator further improves the battery's dynamic performance.

[0127] In the present application, the base film 31 has two opposite surfaces in the thickness direction of itself, Figure 3 The MOF coating 32 in the present application is arranged on the two opposite surfaces of the base film 31. However, the present application is not limited thereto, and in some other examples, the MOF coating 32 can also be arranged on any one surface of the base film 31.

[0128] In some embodiments, the base film 31 can be a porous film with good chemical stability and mechanical stability. Meanwhile, the base film 31 can be a single-layer film or a multi-layer composite film. When the base film 31 is a multi-layer composite film, the materials of the layers can be the same or different, without particular limitation.

[0129] In some embodiments, the material of the base film 31 includes one or more of glass fiber (GF), non-woven fabric, polyethylene (PE), polypropylene (PP), and polyimide (PI).

[0130] In some embodiments, the thickness of the base film 31 is 8 μm to 20 μm, for example, can be 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-amino terephthalic acid and 2,3-diamino terephthalic acid.

[0132] In some embodiments, in the silane-modified calcium-based MOF material, the silane includes one or more of (3-glycidyloxypropyl)trimethoxysilane (GPTMS), (3-glycidyloxypropyl)triethoxysilane, and (3-glycidyloxypropyl)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:(1-15), for example, can be 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 further can be 1:(6-12).

[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, ultrasonic dispersion, and then solvothermal reaction at 100°C to 150°C for 12 hours to 48 hours; centrifuging the mixed solution after reaction, washing the obtained solid product with DMF, and drying at 80°C to 100°C for 4 hours to 8 hours to obtain the calcium-based MOF material. 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 comprises one or more of calcium chloride (CaCl2), calcium nitrate (Ca(NO3)2), calcium sulfate (CaSO4), and calcium oxalate (CaC2O4). It can be appreciated that the calcium salt can or can not contain crystal water, such as CaCl2·2H2O and CaSO4·2H2O, etc.

[0136] In some embodiments, the molar ratio of the calcium salt and the organic ligand is (1-1.5):1, such as 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 comprises 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 comprises the following steps: mixing the calcium-based MOF material and the solvent in a protective atmosphere, adding the silane, and grafting at 100-150°C for 12-48h; centrifuging the mixed solution after the reaction, washing the obtained solid product with DMF, and drying at 60-80°C for 6-18h 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 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 layer 32 further comprises a binder E, and the mass ratio of the silane-modified calcium-based MOF material and the binder E is (90-95):(5-10), and the binder E comprises 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 optionally PVDF.

[0142] In some embodiments, the thickness of the MOF coating layer 32 is 0.5-2μm, such as 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 comprises the following steps: dispersing the silane-modified calcium-based MOF material and the binder E in a solvent (e.g., DMF) to obtain a MOF slurry; coating the MOF slurry on at least one surface of the substrate film 31, and drying at 60-80°C under vacuum for 6-18h to obtain the MOF coating 32.

[0144] The following is a description of some electrolytes for calcium metal batteries.

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

[0146] In some embodiments, the electrolyte of the calcium metal battery uses an electrolyte, 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-trifluoromethanesulfonylimide (Ca(TFSI)2) and calcium trifluoromethanesulfonate (Ca(CF3SO3)2).

[0148] In some embodiments, the concentration of the calcium salt in the electrolyte is 0.1-10 mol / L, 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), methyl ethyl 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, which can effectively improve the corrosion problem of HF to the positive and negative electrodes and improve the cycle stability of the battery.

[0152] In some embodiments, the mass fraction of trimethoxysilyl (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 a further description of the calcium metal battery.

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

[0156] In some embodiments, the calcium metal battery further comprises an outer package for packaging the above electrode assembly and electrolyte. The outer package of the calcium metal battery comprises 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 comprising 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 comprising 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 electric device comprising the calcium metal battery as described above. The calcium metal battery can be used as a power source of the electric device, or as an energy storage unit of the electric device. The electric device can include a mobile device, an electric vehicle, an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto. Among them, the mobile device can be a mobile phone, a notebook computer, etc.; the electric vehicle can be 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 further illustrates with specific examples and comparative examples. The raw materials involved in the following specific examples and comparative examples, if not specifically stated, can be sourced from the market. The instruments used, if not specifically stated, can be sourced from the market. The processes involved, if not specifically stated, are routinely selected by those skilled in the art.

[0161] Example 1

[0162] The calcium metal battery of this example was prepared as follows:

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

[0164] Polymer resin PET and conductive agent CNF (diameter 50 nm, length 1 µm) were mixed in a mass ratio of 100:14, then melt blended at 300 ℃ for 2 h, and after uniform mixing, molded into a film. The polymer resin formed a polymer base film, and the conductive agent was dispersed in the polymer base film. Subsequently, a circular through-hole with a pore size of 60 µm and a pitch of 3000 µm was prepared in the polymer base film by laser etching.

[0165] Poly(3-dodecylthiophene) (P3DDT) was dissolved in toluene to obtain a P3DDT with a P3DDT mass fraction of 3%; conductive agent SP and binder PVDF were added to the P3DDT, with a mass ratio of P3DDT:SP:PVDF of 100:30:10, and ultrasonic dispersion was carried out for 2.5 h to obtain a dispersion liquid; a mask was used to cover the area outside the circular through-hole in the polymer base film, and the dispersion liquid was filled into the circular through-hole by doctor blading, followed by vacuum drying at 70 ℃ 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, vacuumed to 5×10 -5 Pa, argon was introduced at a flow rate of 80 sccm, and direct current magnetron sputtering was carried out under the conditions of a working gas pressure of 2 Pa and a working power of 150 W to form a 1 µm thick Al layer as the positive electrode metal layer on both surfaces of the positive electrode support layer, obtaining a positive electrode current collector.

[0167] The positive electrode material CaV6O 16 ·2.8H2O (CVO) and monomer pyrrole (Py) of conductive polymer D were dispersed in deionized water in a mass ratio of 2:1.1, and oxidant FeCl3 (molar ratio of pyrrole to FeCl3 was 9:11) was added, then in-situ polymerization 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 ℃ for 24 h, obtaining a modified positive electrode material (i.e. CaV6O 16 ·2.8H2O coated with PPy).

[0168] The modified positive electrode material, the conductive agent acetylene black and the binder PVDF were mixed uniformly in a mass ratio of 70:20:10, NMP was added for homogenization to obtain a positive electrode slurry; the positive electrode slurry was coated on two surfaces of the positive electrode current collector, and after drying, rolling and cutting, a positive electrode sheet was obtained.

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

[0170] The polymer resin PP and the conductive agent CNF (diameter of 50 nm, length of 1 µm) were mixed in a mass ratio of 100:14, and then melt blended at 220 ℃ for 4 h. After uniform mixing, the polymer resin formed a polymer base film, and the conductive agent was dispersed in the polymer base film. A circular through-hole with a pore size of 60 µm and a pitch of 3000 µm was prepared in the polymer base film by laser etching. Subsequently, the conductive composition was filled in the circular through-hole by referring to the method of step (1), thereby obtaining a negative electrode support layer with a thickness of 4.5 µm.

[0171] The negative electrode support layer was transferred into the cavity of a magnetron sputtering device, vacuumized to 5×10 -5 Pa, argon was introduced at a flow rate of 60 sccm, and direct current magnetron sputtering was carried out under the conditions of a working gas pressure of 3 Pa and a working power of 250 W to form a CaSn alloy layer with a thickness of 6 µm on both surfaces of the negative electrode support layer as a negative electrode metal layer.

[0172] Poly(3-dodecylthiophene) (P3DDT) was dissolved in toluene to obtain P3DDT with a mass fraction of 3%; 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, and the dispersion was ultrasonically dispersed for 2.5 h to obtain a dispersion liquid; the dispersion liquid was coated on the surface of the negative electrode metal layer, and after vacuum drying at 70 ℃ for 36 h, a negative electrode ion transport layer with a thickness of 1 µm was formed, thereby obtaining a negative electrode current collector which was used as a negative electrode sheet.

[0173] (3) Preparation of the electrolyte:

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

[0175] (4) Preparation of the separator:

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

[0177] Ca-MOF was dispersed in DMF under an N2 atmosphere, followed by the addition of 3-glycidyloxypropyl)trimethoxysilane (GPTMS), and the molar ratio of Ca-MOF to GPTMS was 1:6. The reaction was carried out at 110°C for 12h to graft GPTMS to Ca-MOF through ring-opening reaction between the amino group of Ca-MOF and the epoxy group of GPTMS. After centrifugation, a light yellow precipitate was obtained, which was dried at 70°C under vacuum for 12h to obtain silane-modified Ca-MOF.

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

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

[0180] In a glove box (Ar atmosphere, water and O2 content <0.1 ppm), the positive electrode sheet, the separator film and the negative electrode sheet were packaged with an aluminum plastic film, and after drying to remove water, the electrolyte was injected, then sealed, and after standing, hot and cold pressing, formation, clamping, and capacity distribution processes, the calcium metal battery was obtained.

[0181] Examples 2-6

[0182] Please refer to Table 1, Examples 2-6 are basically the same as Example 1, 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 current collector, the material of the negative metal layer is Ca.

[0185] Example 4: In the electrolyte, the additive is 1% by mass of trimethoxysilane (TMPS).

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

[0187] Example 6: The separator film uses a 12µm thick PE base film without MOF coating.

[0188] Comparative Examples 1-4

[0189] As shown in Table 1, Comparative Examples 1-4 are basically the same as Example 1, and the differences are as follows:

[0190] Comparative Example 1: ① The positive support layer uses a PET film, and the negative support layer uses a PP film, without adding a conductive agent and setting a through-hole structure; ② CVO is used as the positive electrode material, without coating the positive ion transport layer; ③ The negative ion transport layer is not set in the negative current collector; ④ No additive is added to the electrolyte; and ⑤ The separator film does not have a MOF coating.

[0191] Comparative Example 2: ① CVO is used as the positive electrode material, without coating the positive ion transport layer; ② The negative ion transport layer is not set in the negative current collector; ③ No additive is added to the electrolyte; and ④ The separator film does not have a MOF coating.

[0192] Comparative Example 3: ① CVO is used as the positive electrode material, without coating the positive ion transport layer; ② No additive is added to the electrolyte; and ③ The separator film does not have a MOF coating.

[0193] Comparative Example 4: ① The negative ion transport layer is not set in the negative current collector; ② No additive is added to the electrolyte; and ③ The separator film does not have a MOF coating.

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

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

[0196]

[0197] Test Examples

[0198] The following tests were performed on each example and each comparative example:

[0199] (1) Tensile strength: three sample strips with a length of 150 mm and a width of 15 mm were cut, and the samples were placed vertically on the test clamps of the tensile testing machine. After setting the parameters, the tensile strength was detected and recorded.

[0200] (2) Peel strength: the adhesive tape was attached evenly to the steel plate, the sample was fixed to the adhesive tape, the sample surface was attached with an auxiliary tape, and the steel plate and auxiliary tape were fixed to the constant speed tension testing machine to start the test. The peel strength of each sample was recorded.

[0201] (3) Room temperature cycle test: the battery was subjected to a room temperature cycle test at 2C / 2C, and the initial discharge specific capacity of the battery at 2C and the cycle number at which the capacity decayed to 80% were recorded.

[0202] The 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 1-6, the tensile strength of the positive current collector reaches 182 MPa, and the peeling 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 peeling strength reaches 4.7 N / 25 mm, having the advantages of high tensile strength and high peeling strength.

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

[0207] The technical features of the above-described embodiments can be combined arbitrarily, and to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present disclosure.

[0208] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the protection scope of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which 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 high conductance composite current collector, characterized in that, The battery includes a negative electrode sheet, a positive electrode sheet, an electrolyte, and a separator film. 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 provided on at least one surface of the negative electrode support layer, and a negative electrode ion transport layer provided on a surface of the negative electrode metal layer facing 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 sheet 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, the positive electrode ion transport layer includes a conductive polymer D.

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

3. The calcium metal battery of claim 2, wherein, 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-hexyl thiophene, poly(3-dodecyl thiophene), poly(3-dodecyl thiophene-3-hexyl-3-triethylene glycol), and poly(3-octyl pyrrole): 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 metal element-containing material; the inorganic carbon material includes one or more of conductive carbon black, conductive graphite, carbon quantum dots, carbon nanotubes, carbon nanofibers, graphene, and fullerenes; the metal element-containing material includes one or more of copper, aluminum, nickel, gold, silver, and MXene material; (3) The binder B and the binder C each independently include one or more of polyvinylidene fluoride, polytetrafluoroethylene, 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 and 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 and the binder C is 100:(1-15).

4. The calcium metal battery of claim 2, wherein, One or more of the following conditions are met: (1) The thickness of the negative electrode ion transport layer is 0.5 μm-2 μm; (2) The thickness of the negative electrode metal layer is 0.5 μm-10 μm; (3) The thickness of the negative electrode support layer is 4 μm-8 μm; (4) The pore size of the through hole is 10 μm-100 μm, and the spacing between adjacent two through holes is 500 μm-4000 μm.

5. The calcium metal battery of any one of claims 1-4, wherein, One or more of the following conditions are met: (1) the positive electrode material comprises 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 comprises an in-situ polymerization encapsulation method.

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

7. The calcium metal battery of claim 6, wherein, One or more of the following conditions are met: (1) the organic ligand of the calcium-based MOF material comprises one or more of 2-amino terephthalic acid and 2,3-diamino terephthalic acid; (2) the silane comprises 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 layer is 0.5-2 μm.

8. The calcium metal battery of any one of claims 1-4, wherein, The electrolyte comprises a calcium salt, an organic solvent, and an additive, and the additive comprises one or more of trimethoxylphenylsilane and 2-cyano-3-fluoropyridine-5-boronic acid pinacol ester.

9. The calcium metal battery of claim 8, wherein, One or more of the following conditions are met: (1) the calcium salt comprises one or more of calcium hexafluorophosphate, calcium tetrafluoroborate, calcium borohydride, calcium perchlorate, calcium bis-trifluoromethanesulfonylimide, and calcium trifluoromethanesulfonate; (2) the concentration of the calcium salt in the electrolyte is 0.1-10 mol / L; (3) the organic solvent comprises one or more of ethylene carbonate, dimethyl carbonate, methyl ethyl 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 trimethoxylphenylsilane in the electrolyte is 0.1%-5%; (5) the mass fraction of the 2-cyano-3-fluoropyridine-5-boronic acid pinacol ester in the electrolyte is 0.1%-1%.

10. An electrical device, characterized by The calcium metal battery comprises the calcium metal battery of any one of claims 1-9.

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