WO2018152754A1

WO2018152754A1 - Secondary battery and preparation method therefor

Info

Publication number: WO2018152754A1
Application number: PCT/CN2017/074632
Authority: WO
Inventors: 唐永炳; 季必发; 张帆
Original assignee: 深圳先进技术研究院
Priority date: 2017-02-23
Filing date: 2017-02-23
Publication date: 2018-08-30

Abstract

Provided is a secondary battery, comprising a positive electrode, a negative electrode, an electrolytic solution and a diaphragm, wherein the positive electrode comprises positive electrode active materials, and the positive electrode active materials comprise one or more of carbon materials, sulfides, nitrides, oxides, carbides, and a compound of the above-mentioned materials; the negative electrode comprises negative electrode active materials, and the negative electrode active materials comprise one or more of carbon materials, sulfides, nitrides, oxides, carbides, and a compound of the above-mentioned materials; and the electrolytic solution comprises potassium salt and a non-aqueous solvent. The battery is relatively low in cost by taking potassium salt as an electrolyte, and has a high working voltage, high energy density and excellent cycle performance. Further provided is a preparation method for the secondary battery.

Description

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 and a method of fabricating the same.

Background technique

A secondary battery, also called a rechargeable battery, is a battery that can be repeatedly charged and discharged and used multiple times. 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 are lead-acid batteries, nickel-chromium batteries, nickel-hydrogen batteries, and lithium-ion batteries. Among them, lithium ion batteries are the most widely used. However, lithium-ion batteries face the disadvantages of limited lithium resource reserves and high cost. As an energy storage technology that potentially replaces lithium-ion batteries, potassium-ion batteries have received increasing attention in recent years.

Potassium-ion batteries work similarly to lithium-ion batteries, but the storage and release of charge in the battery is achieved by the migration of potassium ions. The core component of the potassium ion battery comprises a positive electrode, a negative electrode and an electrolyte, which realizes energy storage and release 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. When charging, potassium ions are removed from the positive electrode active material and embedded in the negative electrode active material; when discharged, potassium ions are extracted from the negative electrode active material and embedded in the positive electrode active material. Common potassium ion batteries are Prussian blue and its analogues, iron phosphate, iron fluorosulfate and the like as positive electrode active materials, and carbon materials as negative electrode active materials. However, the types of positive and negative materials developed based on potassium ion batteries are very limited, and the research is basically limited to the half cells of potassium plates. The electrochemical performance of potassium ion batteries based on developed materials is not very satisfactory, and the preparation process is also relatively good. complex.

Summary of the invention

In view of this, the first aspect of the present invention provides a secondary battery which uses a material such as carbon as a positive electrode The material and the negative active material, with the potassium salt as the electrolyte, avoid the use of lithium salts with limited resources, which will significantly reduce the cost of the battery and reduce the environmental impact of the battery. In addition, the battery has a dual ion battery working mechanism, the working voltage reaches 4.65V, which is higher than the conventional lithium ion battery, thereby improving the energy density and the electrochemical cycle stability.

Specifically, in a first aspect, the present invention provides a 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 comprising a potassium salt and a non-aqueous solvent;

a negative electrode including a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, the negative electrode active material layer including a negative 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;

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, 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; 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, vanadium dioxide, titanium dioxide, One or more of zinc oxide, copper oxide, 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 anode 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 potassium salt comprises potassium hexafluorophosphate, potassium chloride, potassium fluoride, potassium sulfate, potassium carbonate, potassium phosphate, potassium nitrate, potassium difluorooxalate borate, potassium pyrophosphate, potassium dodecylbenzenesulfonate, ten Potassium dialkyl sulfate, tripotassium citrate, potassium metaborate, potassium borate, potassium molybdate, potassium tungstate, potassium bromide, potassium nitrite, potassium iodate, potassium iodide, potassium silicate, potassium lignosulfonate, Potassium oxalate, potassium aluminate, potassium methanesulfonate, potassium acetate, potassium dichromate, potassium hexafluoroarsenate, potassium tetrafluoroborate, potassium perchlorate, potassium trifluoromethanesulfonimide, trifluoromethanesulfonic acid One or more of potassium; in the electrolyte, the concentration of the potassium 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 (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl formate (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-dioxane Pentane (4MeDOL), dimethoxymethane (DMM), 1,2-dimethoxypropane (DMP), triethylene glycol dimethyl ether (DG), dimethyl sulfone (MSM), dimethyl ether (DME) ), one of vinyl sulfite (ES), propylene sulfite (PS), dimethyl sulfite (DMS), diethyl sulfite (DES), crown ether (12-crown-4) or A variety.

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, Phosphazene, ethanolamine, dimethylamine, cyclobutylsulfone, 1,3-dioxocyclopentane, acetonitrile, long-chain olefin, aluminum oxide, magnesium oxide, cerium oxide, sodium carbonate, calcium carbonate, carbon dioxide, One or more of sulfur dioxide and lithium carbonate.

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

The secondary battery provided by the first aspect of the present invention solves the problem that the existing lithium secondary battery has limited lithium resource reserves by using the potassium salt as the electrolyte, reduces the battery cost and is environmentally friendly; The battery has a higher operating voltage, which increases the energy density of the battery, and the battery has good Good charge and discharge cycle performance.

In a second aspect, the present invention provides a method of preparing a 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;

Providing a negative electrode current collector, preparing a negative electrode active material layer on the negative electrode current collector, drying, pressing, and cutting into a desired size to obtain a negative electrode; the negative electrode active material layer including a negative electrode active material, the negative 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;

Providing an electrolyte and a separator, the electrolyte comprising a potassium salt and a non-aqueous solvent, wherein the anode, the separator, and the cathode are sequentially closely packed in an inert gas or 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 secondary battery.

The method for preparing a 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

FIG. 1 is a schematic structural view of a secondary battery according to an embodiment of the present invention.

detailed description

The following is a preferred embodiment of the embodiments of the present invention, and it should be noted that those skilled in the art can make some improvements without departing from the principles of the embodiments of the present invention. And retouching, these improvements and retouchings are also considered as protection scope of the embodiments of the present invention.

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, a cathode active material layer 50, and a cathode current collector 60. The positive active material layer 20 includes a positive active material that can be embedded in a potassium salt anion, and the positive 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. The anode active material layer 50 includes a cathode active material capable of intercalating potassium ions, the anode active material including one of a carbon material, a sulfide, a nitride, an oxide, a carbide, and a composite of the above materials or The electrolyte 30 includes a potassium salt and a non-aqueous solvent; and the separator 40 is interposed between the positive electrode active material layer 20 and the negative electrode active material layer 50.

The working principle of the above secondary battery provided by the embodiment of the present invention is: during the charging process, the potassium salt anion in the electrolyte migrates to the positive electrode and is embedded in the positive electrode active material, and the potassium ion migrates to the negative electrode and is embedded in the negative active material; During the process, the potassium salt anion is removed from the positive electrode active material into the electrolyte, and at the same time, the potassium ion is removed from the negative electrode into the electrolyte, thereby achieving the entire charge and discharge process. In this process, the electrolyte in the electrolyte is all potassium salt, which solves the problem of limited lithium resource reserves, significantly reduces the cost of the secondary battery, and reduces the environmental impact of the battery.

In an embodiment of the invention, 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, Vanadium dioxide, titanium dioxide, zinc oxide, One or more of copper oxide, nickel oxide, and manganese oxide; the carbide is selected from one or more of titanium carbide, tantalum carbide, molybdenum carbide, and silicon carbide.

In the embodiment of the present invention, the positive electrode active material may be selected from the same material as the negative electrode active material, or different materials may be selected. In the embodiment of the invention, the cathode active material and the anode active material have a layered crystal structure.

In the embodiment of the present invention, the material of the cathode 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 at least one kind a composite material of the above metal elements.

In the embodiment of the present invention, the material of the anode 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 at least one kind a composite material of the above metal elements.

In the embodiment of the present invention, the potassium salt as the electrolyte may be potassium hexafluorophosphate, potassium chloride, potassium fluoride, potassium sulfate, potassium carbonate, potassium phosphate, potassium nitrate, potassium difluorooxalate borate, potassium pyrophosphate, and twelve. Potassium alkylbenzenesulfonate, potassium lauryl sulfate, tripotassium citrate, potassium metaborate, potassium borate, potassium molybdate, potassium tungstate, potassium bromide, potassium nitrite, potassium iodate, potassium iodide, silicic acid Potassium, potassium lignosulfonate, potassium oxalate, potassium aluminate, potassium methanesulfonate, potassium acetate, potassium dichromate, potassium hexafluoroarsenate, potassium tetrafluoroborate, potassium perchlorate, trifluoromethanesulfonimide One or more of potassium and potassium trifluoromethanesulfonate. In the electrolyte, the concentration of the potassium salt may be 0.1 to 10 mol/L. Further, the concentration of the potassium salt may be 0.1 - 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 potassium ions and anions, and the potassium 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), Methyl formate (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 - One or more of 4). 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. Further included are additives which may be one or more of ester, sulfone, ether, nitrile 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, chlorinated carbon Vinyl acetate, bromoethylene carbonate, trifluoroethylphosphonic acid, bromobutyrolactone, fluoroacetoxyethane, phosphate, phosphite, phosphazene, ethanolamine, dimethylamine, cyclobutyl One or more of sulfone, 1,3-dioxocyclopentane, acetonitrile, long-chain olefin, aluminum oxide, magnesium oxide, cerium oxide, sodium carbonate, calcium carbonate, carbon dioxide, sulfur dioxide, and lithium carbonate.

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 content of the positive electrode active material is 60-90 wt%, the content of the conductive agent is 5-30 wt%, and the content of the binder is 5-10 wt. %. The negative active material layer further includes a conductive agent and a binder, wherein the content of the negative electrode active material is 60 to 90% by weight, the content of the conductive agent is 5 to 30% by weight, and the content of the binder is 5 to 10% by weight. 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 one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, SBR rubber, and polyolefin.

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

Step 1. Prepare the positive electrode of the battery: provide a positive current collector with a clean surface, weigh the positive active material, the conductive agent and the binder according to a certain ratio, add a suitable solvent and mix well to form a uniform slurry; then uniformly coat the slurry Forming a positive active material layer on the surface of the positive current collector, and cutting after being completely dried to obtain a positive electrode of a battery of a desired size;

Step 2: preparing a battery negative electrode: providing a surface-cleaning negative electrode current collector, weighing the negative electrode active material, the conductive agent and the binder according to a certain ratio, adding a suitable solvent to mix well to form a uniform slurry; and then uniformly coating the slurry Forming a negative electrode active material layer on the surface of the negative current collector, and cutting after being completely dried to obtain a battery negative electrode of a desired size;

Step 3. Prepare the electrolyte: Weigh a certain amount of potassium salt electrolyte into the non-aqueous solvent, stir well to dissolve, and obtain the desired electrolyte.

Step 4. Preparation of a separator: The porous polymer film or the inorganic porous film is cut into a desired size, and after cleaning, a desired separator is obtained.

Step 5: assembling the battery: the anode, the separator and the positive electrode prepared above are closely stacked in an inert gas or an anhydrous environment, and the electrolyte is added to completely infiltrate the separator, and then the stacked portion is packaged into the battery. The housing is assembled and a secondary battery is obtained.

It is to be noted that although the above steps 1-4 describe the operation of the secondary battery preparation method of the present invention in a specific order, it is not required or implied that these operations must be performed in this specific order. The preparation of steps 1-4 can be carried out simultaneously or in any order.

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

Example 1

A method for preparing a secondary battery, comprising the steps of:

Step 1. Prepare the battery negative electrode: 0.8 g of expanded graphite, 0.1 g of carbon black, 0.1 g of polyvinylidene fluoride is added to 4 mL of the solution of nitromethylpyrrolidone, and thoroughly mixed to obtain a uniform slurry; then the slurry is uniformly coated on the copper. The foil is collected on the surface of the fluid and dried under vacuum. The dried electrode sheet was cut into a disk having a diameter of 12 mm, and compacted as a battery negative electrode.

Step 2. Prepare the separator: Cut the glass fiber paper into a 16 mm diameter disc and use it as a separator.

Step 3. Prepare the electrolyte: weigh 3g of potassium hexafluorophosphate and add 5mL of carbon with a volume ratio of 4:3:2. In a mixed solvent of vinyl acetate, diethyl carbonate and ethyl methyl carbonate, the mixture is stirred until the potassium hexafluorophosphate is completely dissolved, and then a 5% by weight of fluoroethylene carbonate is added as an additive, and the mixture is uniformly stirred and used as an electrolyte. spare.

Step 4, preparing a battery positive electrode: 0.8 g of expanded graphite, 0.1 g of carbon black, 0.1 g of polyvinylidene fluoride is added to 4 mL of a solution of nitromethylpyrrolidone, and thoroughly mixed to obtain a uniform slurry; then the slurry is uniformly coated on the aluminum foil. The surface of the fluid is collected and dried under vacuum. The dried electrode sheet was cut into a disk having a diameter of 10 mm, and compacted as a battery positive electrode.

Step 5: Battery assembly: In the inert gas-protected glove box, the prepared battery negative electrode, the separator, and the battery positive electrode are sequentially closely stacked, the electrolyte is added dropwise to completely infiltrate the separator, and then the stacked portion is packaged into the button battery. The housing is assembled and the secondary battery is obtained.

The working mechanism of the secondary battery of Embodiment 1 of the present invention is: negative electrode:

positive electrode:

The secondary battery of Example 1 of the present invention was subjected to a constant current charge and discharge test with a current density of 100 mA/g and a voltage range of 3-5 V (the electrochemical performance results were obtained by the same test method in the subsequent examples of the present invention). According to the test, the secondary battery of the first embodiment of the present invention has an operating voltage of 4.65 V, a specific capacity of the battery of 66 mAh/g, an energy density of 145 Wh/kg, and a cycle number of 200 times when the capacity is attenuated to 85%. The double graphite secondary battery using the potassium 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, and is environmentally friendly.

Example 2-51

The difference between the embodiment 2-51 and the embodiment 1 is that the negative electrode active material is different, and as shown in Table 1, the secondary battery obtained in the above embodiment is subjected to a constant current charge and discharge test, and the results are shown in Table 1: Table 1

It can be seen from Table 1 that when the negative electrode active material is made of a graphite-based carbon material, the specific capacity of the battery is high, the energy density is high, and the cycle performance is also better.

Example 52-101

The difference between the embodiment 52-101 and the embodiment 1 is that the positive electrode active material is different, and as shown in Table 2, the secondary battery obtained in the above embodiment is subjected to a constant current charge and discharge test, and the results are shown in Table 2:

Table 2

It can be seen from Table 2 that 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.

Examples 102-130

The examples 102-130 differ from the first embodiment only in that the electrolyte salts are different. Specifically, as shown in Table 3, the secondary batteries obtained in the above examples were subjected to a constant current charge and discharge test, and the results are shown in Table 3:

table 3

It can be seen from Table 3 that when the electrolyte is selected from KPF ₆ , KBF ₄ , KClO ₄ , potassium hexafluoroarsenate, potassium trifluoromethanesulfonimide, and potassium trifluoromethanesulfonate, the specific capacity of the battery is higher. Higher density and better cycle stability.

Examples 130-132

The difference between the embodiment 130-132 and the embodiment 1 is that the electrolyte concentration is different. Specifically, as shown in Table 4, the secondary battery obtained in the above embodiment is subjected to a constant current charge and discharge test, and the results are shown in Table 4:

Table 4

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

Examples 133-184

Examples 133-184 differ from Example 1 only in that the types of additives in the electrolyte are different. As shown in Table 5, the secondary batteries obtained in the above examples were subjected to constant current charge and discharge tests. The results are shown in Table 5. :

table 5

As can be seen from Table 5, the electrolyte additive is fluoroethylene carbonate, the battery has higher energy density and more excellent cycle performance.

Examples 185-188

The difference between the embodiment 185-188 and the embodiment 1 is only that the mass content of the additive in the electrolyte is different. Specifically, as shown in Table 6, the secondary battery obtained in the above embodiment is subjected to a constant current charge and discharge test, and the results are shown in the table. 6 shows:

Table 6

As can be seen from Table 6, when the mass content of the electrolyte additive was 5 wt%, the battery energy density was high and the cycle performance was excellent.

Example 189-238

Examples 189-238 differ from Example 1 only in the difference in the solvent type of the electrolyte. Specifically, as shown in Table 7, the secondary battery obtained in the above examples was subjected to a constant current charge and discharge test, and the results are shown in Table 7. Show:

Table 7

As can be seen from Table 7, when the electrolyte solvent is ethylene carbonate + ethyl methyl carbonate + dimethyl carbonate, the energy density of the battery is higher and the cycle performance is excellent.

The secondary battery according to the embodiment of the present invention is not limited to the button battery, and may be designed in the form of a flat battery or a cylindrical battery according to the core component. The secondary battery of the embodiment of the invention uses a potassium salt as an electrolyte, and has a working mechanism of a dual ion battery, and the working voltage reaches 4.65 V, which is higher than a conventional lithium ion battery, thereby improving energy density and having good electrochemical cycle stability. At the same time, the battery preparation cost is low, and has a broad prospect in the field of secondary batteries.

Claims

A 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 comprising a potassium salt and a non-aqueous solvent;

a negative electrode including a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, the negative electrode active material layer including a negative 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;

And a separator interposed between the positive electrode and the negative electrode.
The secondary battery according to claim 1, wherein said carbon material comprises graphite-based carbon material, vitreous carbon, carbon-carbon composite material, carbon fiber, hard carbon, porous carbon, carbon black, carbon nanotube, graphene One or more of them.
The secondary battery according to claim 2, wherein the graphite-based carbon material comprises natural graphite, expanded graphite, artificial graphite, mesocarbon microbead graphite, pyrolytic graphite, highly oriented graphite, and three-dimensional graphite sponge. One or more.
The secondary battery according to claim 1, wherein said sulfide is selected from the group consisting of molybdenum disulfide, tungsten disulfide, vanadium disulfide, titanium disulfide, iron disulfide, ferrous sulfide, nickel sulfide, and zinc sulfide. One or more of cobalt sulfide, manganese sulfide; 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, One or more of 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, molybdenum carbide, carbonization One or more of silicon.
The 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, manganese, or at least one of the above. An alloy of metal elements or a composite material containing at least one of the above metal elements.
The secondary battery according to claim 1, wherein the material of the anode current collector comprises any one of aluminum, copper, iron, tin, zinc, nickel, titanium, manganese, or at least one of the above. An alloy of metal elements or a composite material containing at least one of the above metal elements.
The secondary battery according to claim 1, wherein said potassium salt comprises potassium hexafluorophosphate, potassium chloride, potassium fluoride, potassium sulfate, potassium carbonate, potassium phosphate, potassium nitrate, potassium difluorooxalate borate , potassium pyrophosphate, potassium dodecylbenzenesulfonate, potassium lauryl sulfate, tripotassium citrate, potassium metaborate, potassium borate, potassium molybdate, potassium tungstate, potassium bromide, potassium nitrite, iodine Potassium acid, potassium iodide, potassium silicate, potassium lignosulfonate, potassium oxalate, potassium aluminate, potassium methanesulfonate, potassium acetate, potassium dichromate, potassium hexafluoroarsenate, potassium tetrafluoroborate, potassium perchlorate, One or more of potassium trifluoromethanesulfonimide and potassium trifluoromethanesulfonate; wherein the concentration of the potassium salt in the electrolyte is 0.1-10 mol/L.
The secondary battery according to claim 1, wherein the nonaqueous solvent comprises an organic solvent and an ionic liquid, and the organic solvent comprises one of an ester, a sulfone, an ether, and a nitrile organic solvent. A variety.
The secondary battery according to claim 8, wherein said 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-two Oxycyclopentane, 4-methyl-1,3-dioxocyclopentane, dimethoxymethane, 1,2-dimethoxypropane, triethylene glycol dimethyl ether, dimethyl sulfone, dimethyl ether One or more of vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, and crown ether (12-crown-4).
The secondary battery according to claim 8, wherein said ionic liquid comprises 1-ethyl-3-methylimidazolium-hexafluorophosphate, 1-ethyl-3-methylimidazole-tetrafluoroboron Acid salt, 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-bistrifluoro Methylsulfonimide salt, 1-butyl-1-methylpyrrolidine-bistrifluoromethylsulfonimide salt, N-methyl-N-propylpyrrolidine-bistrifluoromethylsulfonyl One or more of an imine salt, N-methyl, propyl piperidine-bistrifluoromethylsulfonimide salt, N-methyl, butyl piperidine-bistrifluoromethylsulfonimide salt .
The secondary battery according to claim 1, wherein said electrolyte further comprises an additive comprising one or more of an ester, a sulfone, an ether, a nitrile, and an olefin organic additive. The mass fraction of the additive in the electrolyte is from 0.1% to 20%.
The secondary battery according to claim 11, wherein said 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, ethylene sulfite, chlorine Methyl formate, dimethyl sulfoxide, anisole, acetamide, diazabenzene, m-diazabenzene, crown ether 12-crown-4, crown ether 18-crown-6, 4-fluorobenzate Ether, fluorinated chain ether, difluoromethyl ethylene carbonate, trifluoromethyl ethylene carbonate, vinyl chlorocarbonate, vinyl bromoacetate, trifluoroethylphosphonic acid, bromobutyrolactone , fluoroacetoxyethane, phosphate, phosphite, phosphazene, ethanolamine, dimethylamine, cyclobutylsulfone, 1,3-dioxolane, acetonitrile, long-chain olefin, aluminum oxide One or more of magnesium oxide, cerium oxide, sodium carbonate, calcium carbonate, carbon dioxide, sulfur dioxide, and lithium carbonate.
The secondary battery according to claim 1, wherein said separator is an insulating porous A polymer film or an inorganic porous film.
A method for preparing a 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;

Providing a negative electrode current collector, preparing a negative electrode active material layer on the negative electrode current collector, drying, pressing, and cutting into a desired size to obtain a negative electrode; the negative electrode active material layer including a negative electrode active material, the negative 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;

Providing an electrolyte and a separator, the electrolyte comprising a potassium salt and a non-aqueous solvent, wherein the anode, the separator, and the cathode are sequentially closely packed in an inert gas or 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 secondary battery.