WO2018170925A1

WO2018170925A1 - Calcium ion secondary cell, and manufacturing method thereof

Info

Publication number: WO2018170925A1
Application number: PCT/CN2017/078203
Authority: WO
Inventors: 唐永炳; 王蒙; 王恒
Original assignee: 深圳先进技术研究院
Priority date: 2017-03-24
Filing date: 2017-03-24
Publication date: 2018-09-27

Abstract

A calcium ion secondary cell, and manufacturing method thereof. The cell comprises a positive electrode, an electrolyte solution (30), a negative electrode (50), and a separator membrane (40). The positive electrode comprises a positive electrode current collector (10) and a positive electrode active material layer (20) provided on the positive electrode current collector (10). The positive electrode active material layer (20) comprises a positive electrode active material, and the positive electrode active material comprises one or more of a carbon material, sulfide, nitride, oxide, carbide, and a composite of the aforementioned materials. The electrolyte solution (30) comprises a calcium salt and a nonaqueous solvent. The negative electrode (50) comprises a metal foil serving as a negative electrode current collector and a negative electrode active material. The secondary cell employs a calcium salt as an electrolyte to lower costs, and provide a high operation voltage, high capacity, and cycle performance.

Description

Calcium ion-based secondary battery and preparation method thereof

Technical field

The present invention relates to the field of secondary battery technology, and in particular to a secondary battery based on calcium ions and a preparation method thereof.

Background technique

A secondary battery, which can also be called a rechargeable battery, is a rechargeable battery that can be repeatedly charged and discharged. Compared with a non-reusable primary battery, the secondary battery has the advantages of low cost of use and low environmental pollution. At present, the main secondary battery technologies include lead-acid batteries, nickel-chromium batteries, nickel-hydrogen batteries, and lithium-ion batteries. Among them, lithium-ion batteries are the most widely used, and they are the main energy supply methods for portable electronic devices such as mobile phones, notebook computers, and digital cameras. The core component of a lithium ion battery usually comprises a positive electrode, a negative electrode and an electrolyte, and the electrical energy storage and release is achieved by a redox reaction in which ion transport and electron transport phase separation occurs at the interface between the positive electrode, the negative electrode and the electrolyte. The positive electrode of a conventional lithium ion battery is usually composed of a transition metal oxide (LiCoO ₂ , LiNiMnCoO ₂ , LiMn ₂ O ₄ ) or a polyanionic metal compound (LiFePO ₄ ), the negative electrode is composed of a graphite-based material, and the electrolyte is a lithium salt-containing material. Organic solution. Lithium ions are contained in both the positive electrode and the electrolyte. However, lithium reserves on the earth are limited and highly lively, resulting in high prices of existing lithium-ion batteries and certain safety hazards. In addition, the voltage of the conventional lithium ion battery is generally low, and the space for capacity improvement is limited, resulting in a low energy density of the lithium ion battery, which is difficult to meet the needs of new application fields. Therefore, the development of a new energy storage device with high energy density, low manufacturing cost, safety and high efficiency is the focus of current research in the industry. Recently, the team researched and reported a new type of dual-ion battery (patent application number: 201510856238.9), which uses graphite-based carbon material as the positive electrode material, and metal foil (such as aluminum foil) as the negative electrode material and current collector, electrolyte. It is composed of lithium salt and carbonate organic solvent, and the separator is glass fiber paper. The battery has the advantages of low cost, simple process, high working voltage (up to 5V), high energy density and environmental friendliness. However, the battery still does not exclude the use of lithium salt electrolyte. The reserves of lithium on the earth are limited, the price is high, the development cost is large, and it is extremely lively and has potential safety hazards.

Summary of the invention

In view of this, an embodiment of the present invention provides a secondary battery based on calcium ions, which uses a material such as graphite as a positive electrode active material, a metal foil as a negative electrode current collector and a negative electrode active material, and a calcium salt as an electrolyte. The invention aims to solve the problems that the existing lithium secondary battery has limited lithium resource reserves, high cost, low battery energy density, poor cycle stability performance, and safety hazards.

Specifically, in a first aspect, the present invention provides a calcium ion-based secondary battery comprising:

a positive electrode comprising a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, the positive electrode active material layer including a positive electrode active material including a carbon material, a sulfide, a nitride, an oxide, One or more of a carbide, and a composite of the above materials;

An electrolyte, including a calcium salt and a non-aqueous solvent;

a negative electrode comprising a metal foil, the metal foil simultaneously serving as a negative current collector and a negative active material;

And a separator interposed between the positive electrode and the negative electrode.

The carbon material includes one or more of a graphite-based carbon material, a glassy carbon, a carbon-carbon composite material, carbon fiber, hard carbon, porous carbon, carbon black, carbon nanotubes, and graphene.

The graphite-based carbon material includes one or more of natural graphite, expanded graphite, artificial graphite, spherical graphite, flake graphite, mesocarbon microbead graphite, pyrolytic graphite, highly oriented graphite, and three-dimensional graphite sponge.

The sulfide is selected from the group consisting of molybdenum disulfide, tungsten disulfide, vanadium disulfide, titanium disulfide, iron disulfide, ferrous sulfide, nickel sulfide, zinc sulfide, cobalt sulfide, manganese sulfide; Nitride selected from One or more of hexagonal boron nitride and carbon-doped hexagonal boron nitride; the oxide is selected from the group consisting of molybdenum trioxide, tungsten trioxide, vanadium pentoxide, vanadium dioxide, titanium dioxide, zinc oxide, copper oxide One or more of nickel oxide and manganese oxide; the carbide is selected from one or more of titanium carbide, tantalum carbide, molybdenum carbide, and silicon carbide.

The material of the positive electrode current collector includes any one of aluminum, copper, iron, tin, zinc, nickel, titanium, manganese, or an alloy containing at least one of the above metal elements, or a composite containing at least one of the above metal elements. material.

The material of the metal foil includes any one of tin, aluminum, copper, iron, zinc, nickel, titanium, manganese, magnesium, bismuth, or an alloy containing at least one of the above metal elements, or at least one of the above A composite of metal elements.

The calcium salt includes calcium hexafluorophosphate (Ca(PF ₆ ) ₂ ), calcium tetrafluoroborate (Ca(BF ₄ ) ₂ ), calcium chloride, calcium carbonate, calcium fluorosilicate, calcium hexafluoroarsenate, double One of calcium oxalate borate, calcium sulfate, calcium nitrate, calcium fluoride, calcium triflate (Ca(CF ₃ SO ₃ ) ₂ ), calcium perchlorate (Ca(ClO ₄ ) ₂ ) or A plurality of; in the electrolyte, the concentration of the calcium salt is 0.1 - 10 mol / L.

The nonaqueous solvent includes an organic solvent and an ionic liquid, and the organic solvent includes one or more of an ester, a sulfone, an ether, and a nitrile organic solvent.

The organic solvent includes propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl formate, methyl acetate, N,N-dimethylacetamide, fluoroethylene carbonate. Ester, methyl propionate, ethyl propionate, ethyl acetate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxocyclopentane, 4-methyl-1,3-di Oxycyclopentane, dimethoxymethane, 1,2-dimethoxypropane, triethylene glycol dimethyl ether, dimethyl sulfone, dimethyl ether, vinyl sulfite, propylene sulfite, dimethyl sulfite One or more of lipid, diethyl sulfite, and crown ether (12-crown-4).

The ionic liquid includes 1-ethyl-3-methylimidazole-hexafluorophosphate, 1-ethyl-3-methylimidazole-tetrafluoro Borate, 1-ethyl-3-methylimidazole-bistrifluoromethylsulfonimide salt, 1-propyl-3-methylimidazole-hexafluorophosphate, 1-propyl-3-methyl Imidazole-tetrafluoroborate, 1-propyl-3-methylimidazole-bistrifluoromethylsulfonimide salt, 1-butyl-1-methylimidazole-hexafluorophosphate, 1-butyl 1-methylimidazole-tetrafluoroborate, 1-butyl-1-methylimidazole-bistrifluoromethylsulfonimide salt, N-butyl-N-methylpyrrolidine-double Fluoromethylsulfonimide salt, 1-butyl-1-methylpyrrolidine-bistrifluoromethylsulfonimide salt, N-methyl-N-propylpyrrolidine-bistrifluoromethylsulfonate One or more of an imide salt, N-methyl, propyl piperidine-bistrifluoromethylsulfonimide salt, N-methyl, butyl piperidine-bistrifluoromethylsulfonimide salt Kind.

The electrolyte further includes an additive comprising one or more of an ester, a sulfone, an ether, a nitrile, and an olefin organic additive, and the mass fraction of the additive in the electrolyte is 0.1%-20%.

The additives include fluoroethylene carbonate, vinylene carbonate, ethylene carbonate, 1,3-propane sultone, 1,4-butane sultone, vinyl sulphate, propylene sulfate, sulfuric acid Ethylene glycol, vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, ethylene sulfite, methyl chloroformate, dimethyl sulfoxide, anisole, Acetamide, diazabenzene, m-diazabenzene, crown ether 12-crown-4, crown ether 18-crown-6, 4-fluoroanisole, fluorochain ether, difluoromethylethylene carbonate Ester, trifluoromethyl ethylene carbonate, chloroethylene carbonate, vinyl bromoacetate, trifluoroethylphosphonic acid, bromobutyrolactone, fluoroacetoxyethane, phosphate, phosphite, One or more of phosphazene, ethanolamine, dimethylamine, cyclobutylsulfone, 1,3-dioxocyclopentane, acetonitrile, long-chain olefin, sodium carbonate, calcium carbonate, carbon dioxide, sulfur dioxide, lithium carbonate .

The separator is an insulating porous polymer film or an inorganic porous film.

The calcium ion-based secondary battery provided by the first aspect of the present invention uses a calcium salt as an electrolyte, which is lower in cost, higher in operating voltage, higher in capacity, and higher in cycle performance than the conventional commercial lithium ion secondary battery. More excellent, more outstanding security.

In a second aspect, the present invention provides a method for preparing a calcium ion-based secondary battery, comprising the steps of:

Providing a positive electrode current collector, preparing a positive electrode active material layer on the positive electrode current collector, drying, pressing, and cutting into a desired size to obtain a positive electrode; the positive electrode active material layer including a positive electrode active material, the positive electrode active material including carbon a material, a sulfide, a nitride, an oxide, a carbide, and one or more of a composite of the above materials;

Cutting the metal foil into a desired size, after surface cleaning and drying, obtaining a negative electrode; the metal foil simultaneously serving as a negative current collector and a negative active material;

Providing an electrolyte and a separator, the electrolyte comprising a calcium salt and a non-aqueous solvent, the anode, the separator and the cathode are sequentially closely packed in an inert gas and an anhydrous environment, and the electrolyte is added to completely infiltrate the separator Then, the above stacked portion is packaged into a battery case to obtain a calcium ion-based secondary battery.

The method for preparing a calcium ion-based secondary battery provided by the second aspect of the invention has a simple process and is suitable for large-scale production.

The advantages of the invention will be set forth in part in the description which follows.

DRAWINGS

1 is a schematic structural view of a calcium ion-based secondary battery according to an embodiment of the present invention;

2 is a graph showing charge and discharge curves of a calcium ion-based secondary battery according to Embodiment 1 of the present invention;

3 is a graph showing the rate performance of a calcium ion-based secondary battery according to Embodiment 1 of the present invention;

Fig. 4 is a graph showing the cycle performance of a calcium ion-based secondary battery according to Example 1 of the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the drawings and specific embodiments. The following are the preferred embodiments of the embodiments of the present invention, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the embodiments of the present invention. And retouching is also considered to be the scope of protection of the embodiments of the present invention.

Referring to FIG. 1, an embodiment of the present invention provides a secondary battery including a cathode current collector 10, a cathode active material layer 20, an electrolyte 30, a separator 40, and a cathode 50. The cathode current collector 10 and the cathode current collector are disposed. The positive electrode active material layer 20 on 10 collectively constitutes a battery positive electrode, the positive electrode active material layer 20 includes a positive electrode active material; the negative electrode 50 includes a metal foil which serves as both a negative electrode current collector and a negative electrode active material; the electrolytic solution 30 includes A calcium salt and a non-aqueous solvent; the separator 40 is interposed between the positive electrode and the negative electrode 50.

The working principle of the above calcium ion-based secondary battery provided by the embodiment of the present invention is: during the charging process, the calcium salt anion in the electrolyte migrates to the positive electrode and is embedded in the positive active material, and the calcium ion migrates to the negative electrode and forms with the negative electrode. Calcium-metal alloy; during the discharge process, the anion is released from the positive active material back into the electrolyte, and the calcium ion is alloyed from the negative electrode back into the electrolyte to realize the entire charging and discharging process, compared with the conventional lithium ion battery. The calcium ion-based dual ion battery has a higher operating voltage. Since calcium ions are divalent ions, each mole of calcium ion reaction can provide 2 moles of electron transport, which is advantageous for increasing the capacity of the secondary battery. Therefore, the calcium ion-based secondary battery of the embodiment of the present invention has a higher capacity than the existing lithium ion-based dual ion battery.

In the calcium ion-based secondary battery of the present invention, the positive electrode active material is a material such as graphite, the negative electrode is an inexpensive metal foil, and the electrolyte is a calcium salt, and all materials are abundant in storage, cheap and easy to obtain, thereby effectively reducing the secondary battery. Cost of production. Moreover, the metal foil acts as both the negative active material and the negative current collector, which is advantageous for simplifying the production process of the battery, reducing the weight and volume of the battery, improving the energy density and volumetric energy density of the battery, and reducing the cost.

In an embodiment of the invention, the cathode active material includes one or more of a carbon material, a sulfide, a nitride, an oxide, a carbide, and a composite of the above materials. Wherein, the carbon material comprises one or more of a graphite-based carbon material, a glassy carbon, a carbon-carbon composite material, carbon fiber, hard carbon, porous carbon, carbon black, carbon nanotubes, and graphene. Specifically, the graphite-based carbon material includes one or more of natural graphite, expanded graphite, artificial graphite, mesocarbon microbead graphite, pyrolytic graphite, highly oriented graphite, and three-dimensional graphite sponge.

In an embodiment of the invention, the sulfide is selected from the group consisting of molybdenum disulfide, tungsten disulfide, vanadium disulfide, titanium disulfide, iron disulfide, ferrous sulfide, nickel sulfide, zinc sulfide, cobalt sulfide, and manganese sulfide. Or a plurality of; the nitride is selected from one or more of hexagonal boron nitride and carbon-doped hexagonal boron nitride; the oxide is selected from the group consisting of molybdenum trioxide, tungsten trioxide, vanadium pentoxide, One or more of vanadium dioxide, titanium dioxide, zinc oxide, copper oxide, nickel oxide, manganese oxide; the carbide is selected from one or more of titanium carbide, tantalum carbide, molybdenum carbide, silicon carbide.

In an embodiment of the invention, the cathode active material has a layered crystal structure. The calcium salt anion undergoes an intercalation reaction by intercalating-deintercalating the interlayer structure of the positive electrode active material to complete the reaction of the positive electrode.

In the embodiment of the present invention, the material of the metal foil includes any one of tin, aluminum, copper, iron, zinc, nickel, titanium, manganese, magnesium, and antimony, or an alloy containing at least one of the above metal elements. Or a composite material containing at least one of the above metal elements.

In an embodiment of the invention, the cathode current collector comprises any one of aluminum, copper, iron, tin, zinc, nickel, titanium, manganese or an alloy containing at least one of the above metal elements, or contains at least one of the above metals The composite of the elements.

In the embodiment of the present invention, the calcium salt as the electrolyte may be calcium hexafluorophosphate, calcium tetrafluoroborate, calcium chloride, calcium carbonate, calcium fluorosilicate, calcium hexafluoroarsenate, calcium bis(carboxylate) borate, calcium sulfate. One or more of calcium nitrate, calcium fluoride, calcium triflate, calcium perchlorate; in the electrolyte, the concentration of calcium salt The degree is 0.1-10 mol/L. Further, the concentration of the calcium salt may be from 0.1 to 2 mol/L.

In the embodiment of the present invention, the nonaqueous solvent in the electrolytic solution is not particularly limited as long as the electrolyte can be dissociated into calcium ions and anions, and calcium ions and anions can be freely migrated. Specifically, the nonaqueous solvent includes an organic solvent and an ionic liquid, and the organic solvent may be one or more of an ester, a sulfone, an ether, and a nitrile organic solvent. More specifically, the organic solvent may be propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), formic acid Ester (MF), methyl acetate (MA), N,N-dimethylacetamide (DMA), fluoroethylene carbonate (FEC), methyl propionate (MP), ethyl propionate (EP), Ethyl acetate (EA), γ-butyrolactone (GBL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), 1,3-dioxocyclopentane (DOL), 4-methyl-1, 3-dioxocyclopentane (4MeDOL), dimethoxymethane (DMM), 1,2-dimethoxypropane (DMP), triethylene glycol dimethyl ether (DG), dimethyl sulfone (MSM), Dimethyl ether (DME), vinyl sulfite (ES), propylene sulfite (PS), dimethyl sulfite (DMS), diethyl sulfite (DES), crown ether (12-crown-4) One or more of them. The ionic liquid includes 1-ethyl-3-methylimidazolium-hexafluorophosphate, 1-ethyl-3-methylimidazole-tetrafluoroborate, 1-ethyl-3-methylimidazole-double Trifluoromethylsulfonimide salt, 1-propyl-3-methylimidazole-hexafluorophosphate, 1-propyl-3-methylimidazole-tetrafluoroborate, 1-propyl-3- Methylimidazole-bistrifluoromethylsulfonimide salt, 1-butyl-1-methylimidazole-hexafluorophosphate, 1-butyl-1-methylimidazole-tetrafluoroborate, 1- Butyl-1-methylimidazole-bistrifluoromethylsulfonimide salt, N-butyl-N-methylpyrrolidine-bistrifluoromethylsulfonimide salt, 1-butyl-1- Methylpyrrolidine-bistrifluoromethylsulfonimide salt, N-methyl-N-propylpyrrolidine-bistrifluoromethylsulfonimide salt, N-methyl, propyl piperidine-double One or more of fluoromethylsulfonylimide salt, N-methyl, butyl piperidine-bistrifluoromethylsulfonimide salt.

In the embodiment of the present invention, in order to prevent damage caused by volume change of the negative electrode during charge and discharge, the structure of the negative electrode is kept stable, and the service life and performance of the negative electrode are improved to improve the cycle performance of the secondary battery, and the electrolyte further Including additives, the additives may be esters, sulfones, ethers, nitriles One or more of the class and olefinic organic additives. Specifically, the additive includes fluoroethylene carbonate, vinylene carbonate, ethylene carbonate, 1,3-propane sultone, 1,4-butane sultone, vinyl sulfate, propylene sulfate Ester, ethylene sulfate, vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, ethylene sulfite, methyl chloroformate, dimethyl sulfoxide, benzene Methyl ether, acetamide, diazabenzene, m-diazabenzene, crown ether 12-crown-4, crown ether 18-crown-6, 4-fluoroanisole, fluorochain ether, difluoromethyl Ethylene carbonate, trifluoromethyl ethylene carbonate, vinyl chlorocarbonate, vinyl bromoacetate, trifluoroethylphosphonic acid, bromobutyrolactone, fluoroacetoxyethane, phosphate, sub Phosphate, phosphazene, ethanolamine, dimethylamine, cyclobutylsulfone, 1,3-dioxocyclopentane, acetonitrile, long-chain olefin, sodium carbonate, calcium carbonate, carbon dioxide, sulfur dioxide, lithium carbonate Or a variety. The additive added to the electrolyte can form a stable solid electrolyte membrane on the surface of the anode current collector (metal foil), so that the metal foil is not destroyed when reacted as the anode active material, thereby improving the service life of the battery.

In an embodiment of the invention, the additive has a mass fraction in the electrolyte of 0.1-20%, and further may be 2-5%.

In the embodiment of the present invention, the separator may be an insulating porous polymer film or an inorganic porous film, and specifically, one of a porous polypropylene film, a porous polyethylene film, a porous composite polymer film, a glass fiber paper, and a porous ceramic separator may be selected. Or a variety.

In the embodiment of the present invention, the positive electrode active material layer further includes a conductive agent and a binder, wherein the positive electrode active material has a mass content of 60-90%, the conductive agent has a mass content of 5-30%, and the binder has a mass content of 5-10%. Further, the positive electrode active material has a mass content of 70-85%. The conductive agent and the binder are not particularly limited in the embodiment of the present invention, and it is generally used in the art. The conductive agent may be one or more of conductive carbon black, conductive carbon spheres, conductive graphite, carbon nanotubes, conductive carbon fibers, graphene, and reduced graphene oxide. The binder may be polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl One or more of a base cellulose, an SBR rubber, and a polyolefin.

Correspondingly, an embodiment of the present invention further provides a method for preparing the above secondary battery, comprising the following steps:

(1) Preparation of positive electrode: providing a positive electrode current collector with a clean surface, weighing the positive electrode active material, the conductive agent and the binder in a certain ratio, adding a suitable solvent and thoroughly mixing to form a uniform slurry; then uniformly coating the slurry on the slurry Forming a positive electrode current collector surface, forming a positive electrode active material layer, pressing and cutting after being completely dried to obtain a battery positive electrode of a desired size;

(2) preparing a negative electrode: the metal foil is cut into a desired size, and after surface cleaning and drying, a negative electrode is obtained;

(3) Preparation of electrolyte: Weigh a certain amount of calcium salt electrolyte into a non-aqueous solvent, and stir well to obtain the desired electrolyte.

(4) Preparation of a separator: A porous polymer film or an inorganic porous film is cut into a desired size, and after cleaning, a desired separator is obtained.

(5) Battery assembly: in the inert gas and waterless environment, the battery negative electrode, the separator and the positive electrode prepared in the above-mentioned manner are closely stacked in order, the electrolyte is added to completely infiltrate the separator, and then the stacked portion is packaged into the battery. The housing is assembled to obtain a calcium ion-based secondary battery.

It is to be noted that although the above steps (1) to (4) describe the operation of the calcium ion-based secondary battery preparation method of the present invention in a specific order, it is not necessary to perform these operations in this specific order. The operations of steps (1)-(4) can be performed simultaneously or in any order.

The raw materials applied in the above preparation method of the present invention are as described in the foregoing embodiments, and are not described herein again.

The preparation method of the above calcium ion-based secondary battery will be further described below by way of specific examples.

Example 1

(1) Preparation of battery negative electrode: Take a tin foil with a thickness of 0.1 mm, cut into a 12 mm diameter disc, wash with ethanol, dry it and use it as a negative electrode;

(2) Preparation of the separator: The Celgard 2400 porous polymer film was cut into a 16 mm diameter disc, washed with acetone, dried and used as a separator for use;

(3) Preparation of electrolyte: Weigh 1.32g of calcium hexafluorophosphate and add 0.8mL of ethylene carbonate (EC), 0.8mL of propylene carbonate (PC), 1.2mL of dimethyl carbonate (DMC), 1.2mL of ethylene carbonate Ester (EMC), stirred until the calcium hexafluorophosphate is completely dissolved, and used as an electrolyte;

(4) Preparation of battery positive electrode: 0.8g artificial graphite, 0.1g conductive carbon black, 0.1g polyvinylidene fluoride was added to 2mL nitromethylpyrrolidone solution, fully ground to obtain a uniform slurry; then the slurry was uniformly coated The aluminum foil surface (ie, the positive current collector) was dried under vacuum for 12 h. The electrode sheet obtained by drying is cut into a wafer having a diameter of 10 mm, and compacted as a positive electrode of the battery;

(5) Battery assembly: In the inert gas-protected glove box, the prepared negative electrode, separator, and positive electrode are sequentially closely stacked, and the electrolyte is dripped to completely infiltrate the separator, and then the stacked portion is packaged into the button battery case. The battery assembly is completed, and a secondary battery based on calcium ions is obtained.

The secondary battery obtained in Example 1 of the present invention was subjected to a constant current charge and discharge test, and the current density was 100 mA/g, and the voltage range was 3-5 V (the electrochemical conductivity test was carried out by the same test method in the subsequent examples of the present invention). 2 is a charge and discharge graph of a calcium ion-based secondary battery according to an embodiment of the present invention; FIG. 3 is a graph showing a rate performance of a calcium ion-based secondary battery according to an embodiment of the present invention; Cyclic performance map of a calcium ion secondary battery. As can be seen from the figure, the calcium ion-based secondary battery of the present invention has a high discharge voltage, a high capacity, superior rate performance, and superior cycle performance. The secondary battery of the first embodiment of the present invention has an operating average voltage of more than 4.2 V, a specific capacity of the battery of 85.8 mAh/g, an energy density of 168 Wh/kg, and a cycle number of 300 times when the capacity is attenuated to 90%.

The dual ion secondary battery using the calcium salt as the electrolyte in the embodiment 1 of the invention has high working voltage, high energy density, long cycle life, low raw material cost and process cost, environmental friendliness and high safety.

Example 2-11

The preparation process of the secondary batteries of Examples 2-11 and Example 1 was the same except that the materials used in the preparation of the battery negative electrode were the same, and all the other steps and materials used were the same, while the secondary batteries of Examples 2-11 were subjected to the battery. The electrochemical performance test was compared with the performance of Example 1 of the present invention. The negative electrode materials used in Examples 2-11 and their electrochemical properties are shown in Table 1.

Table 1

It can be seen from Table 1 that in the embodiment of the present invention, when the negative electrode is selected from the tin foil, the specific capacity of the battery is higher, the cycle performance is better, and the energy density is the highest.

Example 12-34

The preparation process of the secondary batteries of Examples 12-34 and Example 1 was the same except that the positive electrode active materials used in the preparation of the positive electrode of the battery were the same, and all the steps and materials used were the same, and Examples 12-34 were simultaneously applied. The secondary battery was tested for electrochemical performance of the battery and compared with the performance of Example 1 of the present invention. See Table 2 for details.

Table 2

As can be seen from Table 2, in the embodiment of the present invention, when the cathode active material is selected from a graphite-based carbon material, the specific capacity of the battery is higher, the energy density is higher, and the cycle performance is also better.

Example 35-43

The preparation process of the secondary batteries of Examples 35-43 and Example 1 was the same except that the electrolyte materials used in the preparation of the electrolyte were the same, all the other steps and materials used were the same, and the batteries of the secondary batteries of Examples 35-43 were subjected to the battery. The electrochemical performance test was compared with the performance of Example 1 of the present invention. The electrolyte materials used in Examples 35-43 and the electrochemical performance of the battery are shown in Table 3.

table 3

As can be seen from Table 3, in the examples of the present invention, when the electrolyte is Ca(PF ₆ ) ₂ , Ca(BF ₄ ) ₂ , Ca(CF ₃ SO ₃ ) ₂ , Ca(ClO ₄ ) ₂ , CaF ₂ , The electrochemical performance of the battery is relatively better.

Example 44-48

The preparation process of the secondary batteries of Examples 44-48 and Example 1 was the same except that the electrolyte concentration used in the preparation of the electrolytic solution was different, all other steps and materials used were the same, and the secondary batteries of Examples 44 to 48 were subjected to the battery. The electrochemical performance test was compared with the performance of Example 1 of the present invention. The electrolyte concentration and electrochemical performance of the cells used in Examples 44-48 are detailed in Table 4.

Table 4

As can be seen from Table 4, in the examples of the present invention, when the electrolyte concentration is 1 mol/L, the specific capacity of the battery is high, the energy density is high, and the cycle performance is more excellent.

Examples 49-61

The preparation process of the secondary batteries of Examples 49-61 and Example 1 was the same except that the solvent used in the preparation of the electrolytic solution was the same, all other steps and materials used were the same, and the secondary batteries of Examples 49-61 were subjected to the battery. The electrochemical performance test was compared with the performance of Example 1 of the present invention. The solvents used in Examples 49-61 and their electrochemical properties are detailed in Table 5.

table 5

As can be seen from Table 5, in the embodiment of the present invention, the solvent is ethylene carbonate: propylene carbonate: dimethyl carbonate: ethyl methyl carbonate: (volume ratio 2:2:3:3) mixed solution, The battery has higher specific capacity, higher energy density and better cycle performance.

Example 62-70

The preparation process of the secondary batteries of Examples 62-70 and Example 1 was the same except that the types and amounts of the additives used in the preparation of the electrolytic solution were the same, and all the other steps and materials used were the same, and the secondary batteries of Examples 62-70 were simultaneously used. The electrochemical performance test of the battery was carried out and compared with the performance of Example 1 of the present invention. The solvent materials used in Examples 62-70 and their electrochemical properties are detailed in Table 6.

Table 6

As can be seen from Table 6, in the embodiment of the present invention, some additives are beneficial to increase the energy density or cycle stability of the battery, but the type and amount of additives need further optimization to obtain the best battery performance.

Examples 71-74

The secondary battery preparation processes of Examples 71 to 74 and Example 1 were the same except that the separator materials used in the preparation of the separator were the same, and all the other steps and materials used were the same, while the secondary batteries of Examples 71 to 74 were subjected to the battery. The electrochemical performance test was compared with the performance of Example 1 of the present invention. The separator materials used in Examples 71-74 and their electrochemical properties are detailed in Table 7.

Table 7

As can be seen from Table 7, the selection of different separator materials has no significant effect on the electrochemical performance of the secondary battery.

Examples 75-81

The preparation process of the secondary batteries of Examples 75-81 and Example 1 was the same except that the conductive agent, the type of the binder, and the mass fraction used in the preparation of the positive electrode of the battery were the same, and all the other steps and materials used were the same, and Example 75 was The secondary battery of -81 was subjected to electrochemical performance test of the battery, and compared with the performance of Example 1 of the present invention, the conductive agent, the type of binder and the mass fraction used in Examples 75-81 were specifically See Table 8.

Table 8

As can be seen from Table 8, the selection of different conductive agents, the type of binder and the different addition amounts have no significant effect on the cycle number, energy density and the like of the secondary battery.

The form of the secondary battery according to the present invention is not limited to the button type battery, and may be designed in the form of a prismatic battery, a cylindrical battery, a soft pack battery or the like according to the core component.

The main active component of the secondary battery proposed by the present invention is a material having a layered crystal structure such as graphite, and the electrolyte is a calcium salt rich in resource reserves, environmentally friendly, low in cost, and high in battery capacity. Meanwhile, in the secondary battery system of the present invention, the metal foil serves as both the anode current collector and the anode active material, thereby significantly reducing the battery weight and cost, and improving the energy density of the battery. The average operating voltage of the secondary battery proposed by the present invention is greater than 4.2V.

Claims

A calcium ion-based secondary battery, comprising:

a positive electrode comprising a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, the positive electrode active material layer including a positive electrode active material including a carbon material, a sulfide, a nitride, an oxide, One or more of a carbide, and a composite of the above materials;

An electrolyte, including a calcium salt and a non-aqueous solvent;

a negative electrode comprising a metal foil, the metal foil simultaneously serving as a negative current collector and a negative active material;

And a separator interposed between the positive electrode and the negative electrode.
The calcium ion-based secondary battery according to claim 1, wherein the carbon material comprises a graphite-based carbon material, a glassy carbon, a carbon-carbon composite material, carbon fiber, hard carbon, porous carbon, carbon black, carbon nanometer. One or more of tubes and graphene.
The calcium ion-based secondary battery according to claim 2, wherein the graphite-based carbon material comprises natural graphite, expanded graphite, artificial graphite, spherical graphite, flake graphite, mesocarbon microbead graphite, pyrolysis One or more of graphite, highly oriented graphite, and three-dimensional graphite sponge.
The calcium ion-based secondary battery according to claim 1, wherein the sulfide is selected from the group consisting of molybdenum disulfide, tungsten disulfide, vanadium disulfide, titanium disulfide, iron disulfide, ferrous sulfide, and vulcanization. One or more of nickel, zinc sulfide, cobalt sulfide, and manganese sulfide; the nitride is selected from one or more of hexagonal boron nitride and carbon-doped hexagonal boron nitride; and the oxide is selected from the group consisting of One or more of molybdenum trioxide, tungsten trioxide, vanadium pentoxide, vanadium dioxide, titanium dioxide, zinc oxide, copper oxide, nickel oxide, manganese oxide; the carbide is selected from the group consisting of titanium carbide, tantalum carbide, One or more of molybdenum carbide and silicon carbide.
The calcium ion-based secondary battery according to claim 1, wherein the material of the positive electrode current collector comprises any one of aluminum, copper, iron, tin, zinc, nickel, titanium, and manganese, or contains at least An alloy of the above metal elements or a composite material containing at least one of the above metal elements.
The calcium ion-based secondary battery according to claim 1, wherein the material of the metal foil comprises any one of tin, aluminum, copper, iron, zinc, nickel, titanium, manganese, magnesium, and antimony. Or an alloy containing at least one of the above metal elements, or a composite material containing at least one of the above metal elements.
The calcium ion-based secondary battery according to claim 1, wherein the calcium salt comprises calcium hexafluorophosphate, calcium tetrafluoroborate, calcium chloride, calcium carbonate, calcium fluorosilicate, hexafluoroarsenic acid. One or more of calcium, calcium oxalate borate, calcium sulfate, calcium nitrate, calcium fluoride, calcium triflate, calcium perchlorate; in the electrolyte, the concentration of the calcium salt is 0.1 –10 mol/L.
The calcium ion-based secondary battery according to claim 1, wherein the nonaqueous solvent comprises an organic solvent and an ionic liquid, and the organic solvent comprises an organic solvent such as an ester, a sulfone, an ether or a nitrile. One or more.
The calcium ion-based secondary battery according to claim 8, wherein the organic solvent comprises propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl formate. , methyl acetate, N,N-dimethylacetamide, fluoroethylene carbonate, methyl propionate, ethyl propionate, ethyl acetate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1 , 3-dioxolane, 4-methyl-1,3-dioxocyclopentane, dimethoxymethane, 1,2-dimethoxypropane, triethylene glycol dimethyl ether, dimethyl sulfone One or more of dimethyl ether, vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, and crown ether (12-crown-4).
The calcium ion-based secondary battery according to claim 8, wherein the ionic liquid comprises 1-ethyl-3-methylimidazole-hexafluorophosphate or 1-ethyl-3-methylimidazole -tetrafluoroborate, 1-ethyl-3-methylimidazole-bistrifluoromethylsulfonimide salt, 1-propyl-3-methylimidazole-hexafluorophosphate, 1-propyl- 3-methylimidazole-tetrafluoroborate, 1-propyl-3-methylimidazole-bistrifluoromethylsulfonimide salt, 1-butyl-1-methylimidazole-hexafluorophosphate, 1-butyl-1-methylimidazole-tetrafluoroborate, 1-butyl-1-methylimidazole-double Trifluoromethylsulfonimide salt, N-butyl-N-methylpyrrolidine-bistrifluoromethylsulfonimide salt, 1-butyl-1-methylpyrrolidine-bistrifluoromethyl Sulfonimide salt, N-methyl-N-propylpyrrolidine-bistrifluoromethylsulfonimide salt, N-methyl, propyl piperidine-bistrifluoromethylsulfonimide salt, N One or more of a, butyl piperidine-bistrifluoromethylsulfonimide salt.
The calcium ion-based secondary battery according to claim 1, wherein the electrolyte further comprises an additive, wherein the additive comprises an ester, a sulfone, an ether, a nitrile, and an olefin organic additive. One or more of the additives have a mass fraction in the electrolyte of from 0.1% to 20%.
The calcium ion-based secondary battery according to claim 11, wherein the additive comprises fluoroethylene carbonate, vinylene carbonate, ethylene carbonate, 1,3-propane sultone, 1,4-butane sultone, vinyl sulphate, propylene sulfate, ethylene sulphate, vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, sulfite Ethyl ester, methyl chloroformate, dimethyl sulfoxide, anisole, acetamide, diazabenzene, m-diazabenzene, crown ether 12-crown-4, crown ether 18-crown-6, 4 -Fluoroanisole, fluorinated chain ether, difluoromethyl ethylene carbonate, trifluoromethyl ethylene carbonate, vinyl chlorocarbonate, vinyl bromoacetate, trifluoroethylphosphonic acid, bromine Butyrolactone, fluoroacetoxyethane, phosphate, phosphite, phosphazene, ethanolamine, dimethylamine, cyclobutylsulfone, 1,3-dioxocyclopentane, acetonitrile, long-chain olefins, One or more of sodium carbonate, calcium carbonate, carbon dioxide, sulfur dioxide, and lithium carbonate.
The calcium ion-based secondary battery according to claim 1, wherein the separator is an insulating porous polymer film or an inorganic porous film.
A method for preparing a calcium ion-based secondary battery, comprising the steps of:

Providing a positive electrode current collector, preparing a positive electrode active material layer on the positive electrode current collector, drying, pressing, and cutting into a desired size to obtain a positive electrode; the positive electrode active material layer including a positive electrode active material, the positive electrode active material including carbon Materials, sulfides, nitrides, oxides, carbides, and the like One or more of the complexes;

Cutting the metal foil into a desired size, after surface cleaning and drying, obtaining a negative electrode; the metal foil simultaneously serving as a negative current collector and a negative active material;

Providing an electrolyte and a separator, the electrolyte comprising a calcium salt and a non-aqueous solvent, the anode, the separator and the cathode are sequentially closely packed in an inert gas and an anhydrous environment, and the electrolyte is added to completely infiltrate the separator Then, the above stacked portion is packaged into a battery case to obtain a calcium ion-based secondary battery.