Rechargeable magnesium ion battery electrolyte and rechargeable magnesium ion battery

Abstract

The present invention discloses a rechargeable magnesium-ion battery electrolyte and a rechargeable magnesium-ion battery. The electrolyte contains one or more metal ions selected from chromium, manganese, iron, cobalt, nickel, copper, zinc, and silver ions, thereby preparing the rechargeable magnesium-ion battery. Alternatively, the metal ions are introduced into the rechargeable magnesium-ion battery in the form of metal clips or added to the positive and / or negative electrodes. The rechargeable magnesium-ion battery of the present invention has high capacity and good rate performance, low battery cost, and high safety.

Description

Technical Field

[0001] The invention belongs to the technical field of rechargeable batteries, and in particular relates to a rechargeable magnesium ion electrolyte and a rechargeable magnesium ion battery. Background Art

[0002] Magnesium is located diagonally opposite lithium in the periodic table, with similar ionic radius and chemical properties. Due to the characteristics of magnesium ions as positive divalent ions, magnesium has a high mass energy density (2205mAh·g -1 ) and volume energy density (3833mAh·cm -3 ); magnesium is extremely abundant in the Earth's crust (1.5wt%), ranking eighth, approximately 104 times more abundant than lithium; and magnesium is inexpensive, about 1 / 83 times more expensive than lithium. my country, with its abundant magnesium resources, offers unique advantages for developing magnesium-ion batteries. With the increasing popularity of electric vehicles and the trend toward large-scale energy storage, rechargeable magnesium-ion batteries hold broad application prospects.

[0003] Currently, rechargeable magnesium-ion batteries generally have a low capacity. The reason is that the magnesium ions in the electrolyte are severely solvated, and their migration into the material requires overcoming a large energy barrier, and the magnesium ions move slowly, resulting in low capacity, poor cycle stability, and poor rate performance of rechargeable magnesium-ion batteries. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the rechargeable magnesium ion battery in the prior art has low specific capacity, poor cycle stability and poor rate performance.

[0005] The inventors discovered that introducing metal ions into the electrolyte can reduce the solvation of magnesium ions, allowing more magnesium ions to react with the positive and negative electrode materials, thereby generating more capacity; the desolvated magnesium ions can be rapidly transported between the positive and negative electrodes and can maintain the structural stability of the active materials, thereby exhibiting excellent rate performance and cycle stability, thus completing the present invention.

[0006] In one aspect, the present invention provides a rechargeable magnesium ion battery electrolyte, which is composed of a magnesium salt, a solvent and metal ions, wherein the metal ions are selected from one or more of chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions and silver ions.

[0007] Furthermore, the magnesium salt is selected from one or more of magnesium chloride, magnesium fluoride, magnesium bromide, magnesium iodide, magnesium borohydride, magnesium perchlorate, magnesium nitrate, magnesium sulfate, magnesium chromate, magnesium acetate, magnesium hexafluoride, bis(hexamethyldisilazide)magnesium, bis(trifluoromethanesulfonyl)imide magnesium, bis(fluorosulfonyl)imide magnesium and magnesium trifluoromethanesulfonate.

[0008] Furthermore, the solvent is selected from one or more of water, acetonitrile, ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, dioxane, polyethylene glycol dimethyl ether, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, dimethyl ether, diethyl ether, methyl formate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate, and ethyl butyrate.

[0009] Furthermore, the molar concentration of the magnesium salt is 0.01 mol / L-10 mol / L.

[0010] Furthermore, the molar mass ratio of the magnesium salt to the metal ion is 1:0.01-5.

[0011] In another aspect, the present invention provides a method for preparing the above-mentioned rechargeable magnesium ion battery electrolyte, the method comprising:

[0012] A. When metal ions are added to the electrolyte in the form of their metal salts, the preparation method includes:

[0013] In air or an inert atmosphere, magnesium salt and metal salt containing metal ions are weighed according to mass fraction and added to a solvent, and stirred at room temperature for 0.5-2 hours to completely dissolve them to obtain the rechargeable magnesium ion battery electrolyte; or,

[0014] B. When metal ions are added to the electrolyte in the form of an oxidized metal current collector, the preparation method includes:

[0015] Step 1: Solvent pretreatment

[0016] The solvent is measured and added to the electrolytic cell. The metal is used as the working electrode, the platinum wire is used as the counter electrode, and the calomel electrode is used as the reference electrode. The three-electrode system is connected to the electrochemical workstation and cyclic voltammetry is performed to obtain the solvent containing the metal ions.

[0017] Step 2: Preparation of electrolyte

[0018] In air or in an argon glove box, magnesium salt is added to the above-mentioned solvent containing metal ions and mixed, and stirred at room temperature for 0.5-2 hours to completely dissolve it, thereby obtaining the rechargeable magnesium ion battery electrolyte.

[0019] Furthermore, the metal in step 1 of method B is selected from chromium, manganese, iron, cobalt, nickel, copper, zinc, and silver, and the metal is a corresponding metal sheet.

[0020] In another aspect, the present invention provides a rechargeable magnesium ion battery comprising a battery case, a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and an electrolyte containing the rechargeable magnesium ion battery.

[0021] In another aspect, the present invention provides a rechargeable magnesium ion battery comprising a battery case, a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and an electrolyte containing a magnesium salt, wherein:

[0022] There is a metal interlayer between the positive electrode and the separator, and / or there is a metal interlayer between the negative electrode and the separator, and the metal interlayer is a metal sheet selected from chromium, manganese, iron, cobalt, nickel, copper, zinc, and silver; or

[0023] The positive electrode and / or the negative electrode contain metal ions, and the metal ions are selected from one or more of chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, and silver ions.

[0024] Furthermore, the active material of the positive electrode is one or more of graphite, expanded graphite, natural graphite, fluorinated graphite, amorphous carbon, Ketjen black, carbon black, polytriphenylamine (PTPAn), 1,4-diphenylaminobenzene, polyaniline, polyvinylcarbazole, molybdenum disulfide, copper oxide, and cuprous oxide, and optionally contains metal ions, and the metal ions are selected from one or more of chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, and silver ions.

[0025] Furthermore, the active material of the negative electrode is activated carbon, titanium dioxide, Li4Ti5O 12 , molybdenum disulfide, molybdenum diselenide, cobalt tetroxide, niobium pentoxide, 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), anthraquinone (PAQ), perylene diimide-ethylenediamine (PDI-EDA), and optionally containing metal ions, wherein the metal ions are selected from one or more of chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, and silver ions.

[0026] The metal ions contained in the positive electrode and / or negative electrode are in the form of metal salts, for example, metal chlorides such as silver chloride and cobalt chloride, or metal nitrates such as copper nitrate.

[0027] In another aspect, the present invention provides a method for preparing the above-mentioned rechargeable magnesium ion battery, the method comprising:

[0028] The positive electrode active material, conductive agent and binder are mixed, a solvent is added dropwise, and then ball milled to obtain a homogenous slurry, which is then coated on a positive electrode current collector and dried to remove the solvent to prepare a positive electrode sheet; the positive electrode current collector is selected from one of copper, aluminum, stainless steel, nickel, molybdenum, Hastelloy, titanium and carbon;

[0029] The negative electrode active material, conductive agent and binder are mixed, a solvent is added dropwise, and then ball milled to obtain a homogenous slurry, which is then coated on a negative electrode current collector and dried to remove the solvent to prepare a negative electrode sheet; the negative electrode current collector is selected from one of copper, aluminum, stainless steel, nickel, molybdenum, Hastelloy, titanium and carbon;

[0030] The prepared positive electrode sheet, negative electrode sheet, electrolyte, separator and possible metal interlayer are assembled into a battery.

[0031] The advantages of the present invention are:

[0032] The invention relates to a method for directly introducing metal salts of one or more metal ions selected from chromium, manganese, iron, cobalt, nickel, copper, zinc, and silver into the electrolyte of a rechargeable magnesium-ion battery, or by adding the metal ions to a current collector containing the metals described above; or by placing a metal sheet selected from chromium, manganese, iron, cobalt, nickel, copper, zinc, and silver between the positive electrode and the separator, or between the negative electrode and the separator, in the form of a metal interlayer; or by adding metal salts selected from chromium, manganese, iron, cobalt, nickel, copper, zinc, and silver to the positive and / or negative electrodes of the rechargeable magnesium-ion battery during the preparation of the positive and negative electrodes. The introduction of metal ions in the electrolyte helps reduce magnesium ion solvation, allowing more exposed magnesium ions to react with the electrode material to increase capacity. The desolvated magnesium ions can be rapidly transported between the positive and negative electrodes while maintaining the structural stability of the active materials, thereby exhibiting excellent rate capability and cycling stability.

[0033] Compared with the prior art, the battery prepared by the rechargeable magnesium ion battery electrolyte of the present invention, or the rechargeable magnesium ion battery in which the above-mentioned metal ions are introduced in the form of a metal interlayer, a metal current collector, or a metal salt, has a cyclic discharge capacity of at least 250 mAh / g at room temperature and can be discharged at an ultra-high current density (above 5 A / g). BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 4 is the discharge voltage-specific capacity relationship curve of the rechargeable magnesium ion battery obtained in Example 4 of the present invention.

[0035] Figure 2 3 is a curve showing the relationship between the discharge specific capacity and the number of cycles of the rechargeable magnesium ion battery obtained in Example 4 of the present invention and the rechargeable magnesium ion battery obtained in Comparative Example 1. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a rechargeable magnesium ion battery electrolyte, and its preparation method includes: in air or in an argon glove box, adding 5.8458 g of magnesium bis(trifluoromethylsulfonyl)imide and 187.56 mg of copper nitrate to 10 mL of acetonitrile, mixing, and stirring at room temperature for 1 hour to completely dissolve them, to obtain the rechargeable magnesium ion battery electrolyte: an acetonitrile solution containing 1 M magnesium bis(trifluoromethylsulfonyl)imide and 0.1 M copper nitrate.

[0039] Example 2

[0040] This embodiment provides a rechargeable magnesium ion battery electrolyte, and its preparation method includes:

[0041] Step 1: Solvent pretreatment

[0042] Measure 20 mL of acetonitrile solvent and add it to an electrolytic cell. Use a manganese metal sheet as the working electrode, a platinum wire as the counter electrode, and a calomel electrode as the reference electrode. Connect this three-electrode system to an electrochemical workstation and perform cyclic voltammetry to obtain the acetonitrile solvent containing manganese ions.

[0043] Step 2: Preparation of electrolyte

[0044] In air or in an argon glove box, 5.8458 g of magnesium bis(trifluoromethylsulfonyl)imide was added to 10 mL of the above-mentioned acetonitrile solvent containing manganese ions, and the mixture was stirred at room temperature for 1 hour to completely dissolve it, thereby obtaining the rechargeable magnesium ion battery electrolyte: an acetonitrile solution containing 1 M magnesium bis(trifluoromethylsulfonyl)imide and manganese ions.

[0045] Example 3

[0046] This embodiment provides a rechargeable magnesium ion battery electrolyte, and its preparation method includes:

[0047] Step 1: Solvent pretreatment

[0048] 20 mL of tetrahydrofuran and acetonitrile (1:1 volume ratio) were added to an electrolytic cell. A nickel foam was used as the working electrode, a platinum wire as the counter electrode, and a calomel electrode as the reference electrode. This three-electrode system was connected to an electrochemical workstation and subjected to cyclic voltammetry to obtain a tetrahydrofuran and acetonitrile solvent mixture containing nickel ions.

[0049] Step 2: Preparation of electrolyte

[0050] In air or in an argon glove box, 2.232 g of magnesium perchlorate was added to 10 mL of the above-mentioned mixed solvent of tetrahydrofuran and acetonitrile containing nickel ions, and the mixture was stirred at room temperature for 1 hour to completely dissolve it, thereby obtaining the rechargeable magnesium ion battery electrolyte: a mixed solution of tetrahydrofuran and acetonitrile containing 1 M magnesium perchlorate and nickel ions (volume ratio of 1:1).

[0051] Example 4

[0052] This embodiment provides a rechargeable magnesium-ion battery comprising a positive electrode, a separator, a copper interlayer, a negative electrode, and a rechargeable magnesium-ion electrolyte. The positive electrode active material is commercially available graphite, the negative electrode material is 3,4,9,10-perylenetetracarboxylic acid diimide, and the electrolyte is a 1M solution of magnesium bis(trifluoromethylsulfonyl)imide in acetonitrile and water (volume ratio: 50:1).

[0053] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0054] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0055] The prepared positive electrode sheet, glass fiber separator, copper interlayer, negative electrode sheet, and electrolyte were assembled into a CR2032 button cell. Then a constant current discharge-charge cycle test was performed. At a charge and discharge current density of 5A / g, the discharge curves for the first three cycles were as follows: Figure 1 As shown in the figure, the discharge platform is 1.15V and the first discharge capacity is 249mAh / g. Figure 2 As shown, the stable capacity is 250 mAh / g.

[0056] Example 5

[0057] This embodiment provides a rechargeable magnesium ion battery, comprising a positive electrode, a separator, a negative electrode, and a rechargeable magnesium ion electrolyte.

[0058] The positive electrode active material is commercial graphite, the negative electrode material is 3,4,9,10-perylenetetracarboxylic diimide, and the electrolyte is the acetonitrile solution obtained in Example 1 containing 1M magnesium bis(trifluoromethylsulfonyl)imide and 0.1M copper nitrate.

[0059] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0060] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0061] The prepared positive and negative electrodes, rechargeable magnesium ion electrolyte, and glass fiber separator were assembled into a CR2032 button cell. Constant current discharge-charge cycling tests were then performed. At a charge and discharge current density of 5 A / g, the stable capacity was 214 mAh / g.

[0062] Example 6

[0063] This embodiment provides a rechargeable magnesium-ion battery comprising a positive electrode, a separator, a negative electrode, and a rechargeable magnesium-ion electrolyte. The positive electrode active material is graphite fluoride, the negative electrode material is anthraquinone, and the electrolyte is an acetonitrile solution containing 1M magnesium bis(trifluoromethylsulfonyl)imide and manganese ions obtained in Example 2.

[0064] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0065] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0066] The prepared positive and negative electrodes, rechargeable magnesium ion electrolyte, and glass fiber separator were assembled into a CR2032 button cell. Constant current discharge-charge cycling tests were then performed. At a charge and discharge current density of 5 A / g, the stable capacity was 223 mAh / g.

[0067] Example 7

[0068] This embodiment provides a rechargeable magnesium-ion battery comprising a positive electrode, a negative electrode, a separator, and a rechargeable magnesium-ion electrolyte. The positive electrode active material is amorphous carbon, the negative electrode material is perylenediimide-ethylenediamine, and the electrolyte is a mixed solution of tetrahydrofuran and acetonitrile (1:1 volume ratio) containing 1M magnesium perchlorate and nickel ions as described in Example 3.

[0069] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0070] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0071] The prepared positive and negative electrodes, rechargeable magnesium ion electrolyte, and glass fiber separator were assembled into a CR2032 button cell. Constant current discharge-charge cycling tests were then performed. At a charge and discharge current density of 5 A / g, the stable capacity was 234 mAh / g.

[0072] Example 8

[0073] This embodiment provides a rechargeable magnesium-ion battery comprising a positive electrode, a separator, a negative electrode, and a rechargeable magnesium-ion electrolyte. The positive electrode active material is commercially available graphite and silver chloride (in a molar ratio of 10:1), the negative electrode material is molybdenum disulfide, and the electrolyte is an acetonitrile solution containing 1M magnesium bis(trifluoromethylsulfonyl)imide.

[0074] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0075] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0076] The prepared positive and negative electrodes, rechargeable magnesium ion electrolyte, and glass fiber separator were assembled into a CR2032 button cell. Constant current discharge-charge cycling tests were then performed. At a charge and discharge current density of 5 A / g, the stable capacity was 215 mAh / g.

[0077] Example 9

[0078] This embodiment provides a rechargeable magnesium-ion battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte. The positive electrode active material is polyaniline, the negative electrode material is titanium dioxide and cobalt chloride (molar ratio of 10:1), and the electrolyte is the acetonitrile solution containing 1M magnesium bis(trifluoromethylsulfonyl)imide and manganese ions as described in Example 2.

[0079] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0080] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0081] The prepared positive and negative electrodes, rechargeable magnesium ion electrolyte, and glass fiber separator were assembled into a CR2032 button cell. Constant current discharge-charge cycling tests were then performed. At a charge and discharge current density of 5 A / g, the cell achieved a capacity of 156 mAh / g.

[0082] Comparative Example 1

[0083] This comparative example provides a rechargeable magnesium ion battery, comprising a positive electrode, a separator, a negative electrode, and an electrolyte, wherein the positive electrode active material is commercial graphite, the negative electrode material is 3,4,9,10-perylenetetracarboxylic diimide, and the electrolyte is an acetonitrile solution containing 1M magnesium bis(trifluoromethylsulfonyl)imide.

[0084] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0085] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0086] The prepared positive electrode sheet, negative electrode sheet, rechargeable magnesium ion electrolyte, and glass fiber separator were assembled into a CR2032 button battery. Then a constant current discharge-charge cycle test was performed. At a charge and discharge current density of 5A / g, the cycle performance was as follows: Figure 2 As shown, the stable capacity is 65 mAh / g.

[0087] Comparative Example 2

[0088] This comparative example provides a rechargeable magnesium ion battery, comprising a positive electrode, a separator, a negative electrode and an electrolyte, wherein the positive electrode active material is graphite fluoride, the negative electrode material is anthraquinone, and the electrolyte is an acetonitrile solution containing 1M magnesium bis(trifluoromethylsulfonyl)imide.

[0089] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0090] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0091] The prepared positive and negative electrodes, rechargeable magnesium ion electrolyte, and glass fiber separator were assembled into a CR2032 button cell. Constant current discharge-charge cycling tests were then performed. At a charge and discharge current density of 5 A / g, the stable capacity was 57 mAh / g.

[0092] Comparative Example 3

[0093] This comparative example provides a rechargeable magnesium ion battery, comprising a positive electrode, a separator, a negative electrode and an electrolyte, wherein the positive electrode active material is amorphous carbon, the negative electrode material is perylene diimide-ethylenediamine, and the electrolyte is an acetonitrile solution containing 1M magnesium perchlorate.

[0094] The positive electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 8:1:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to obtain a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a positive electrode sheet.

[0095] The negative electrode active material, acetylene black and polyvinylidene fluoride binder solution were mixed in a mass ratio of 7:2:1 (wherein the mass of the binder is the mass of the solute contained), 3 drops of solvent were added, and the mixture was ball-milled for 4 cycles at a speed of 350 r / min to prepare a homogenous slurry, which was then coated on a carbon current collector with a thickness of 100 μm, and dried to remove the solvent to prepare a negative electrode sheet.

[0096] The prepared positive and negative electrodes, rechargeable magnesium ion electrolyte, and glass fiber separator were assembled into a CR2032 button cell. Constant current discharge-charge cycling tests were then performed. At a charge and discharge current density of 5 A / g, the stable capacity was 50 mAh / g.

[0097] In summary, the metal-ion-containing rechargeable magnesium-ion battery of the present invention has low raw material costs and is prepared by oxidizing the metal-containing current collector and metal interlayer and adding the metal salt to the battery material or electrolyte. The addition of metal ions helps reduce solvation in magnesium-ion batteries, allowing more exposed magnesium ions to react with the electrode material to increase capacity, improve cycle stability and rate performance, and thus has excellent commercial application prospects. Furthermore, the present invention has a simple preparation process and is amenable to large-scale industrial production.

Claims

1. A rechargeable magnesium ion battery comprising a battery case, a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and a rechargeable magnesium ion battery electrolyte, wherein the rechargeable magnesium ion battery electrolyte is composed of a magnesium salt, a solvent, and metal ions, wherein the metal ions are selected from one or more of chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, and silver ions; The solvent is selected from water, acetonitrile, diethyl ether, or a mixture of tetrahydrofuran and acetonitrile; The active materials of the negative electrode are activated carbon, titanium dioxide, Li4Ti5O 12 , one or more of molybdenum disulfide, molybdenum diselenide, cobalt tetroxide, niobium pentoxide, 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), anthraquinone (PAQ), and perylene diimide-ethylenediamine (PDI-EDA); The rechargeable magnesium ion battery electrolyte is prepared by the following preparation method: A. When metal ions are added to the electrolyte in the form of their metal salts, the preparation method includes: In an air or inert atmosphere, the magnesium salt and the metal salt containing metal ions are weighed according to mass fraction and added to the solvent, and stirred at room temperature for 0.5-2 hours to completely dissolve them, thereby obtaining the rechargeable magnesium ion battery electrolyte; or, B. When metal ions are added to the electrolyte in the form of oxidized metal current collectors, the preparation method includes: Step 1: Solvent pretreatment The solvent is measured and added to the electrolytic cell. The metal is used as the working electrode, the platinum wire is used as the counter electrode, and the calomel electrode is used as the reference electrode. The three-electrode system is connected to the electrochemical workstation and cyclic voltammetry is performed to obtain the solvent containing the metal ions. Step 2: Preparation of electrolyte In air or in an argon glove box, magnesium salt is added to the above-mentioned solvent containing metal ions and mixed, and stirred at room temperature for 0.5-2 hours to completely dissolve it, thereby obtaining the rechargeable magnesium ion battery electrolyte.

2. The rechargeable magnesium ion battery according to claim 1, characterized in that The magnesium salt is selected from one or more of magnesium chloride, magnesium fluoride, magnesium bromide, magnesium iodide, magnesium borohydride, magnesium perchlorate, magnesium nitrate, magnesium sulfate, magnesium chromate, magnesium acetate, magnesium hexafluoride, bis(hexamethyldisilazide)magnesium, bis(trifluoromethanesulfonyl)imide magnesium, bis(fluorosulfonyl)imide magnesium and magnesium trifluoromethanesulfonate.

3. The rechargeable magnesium ion battery according to claim 1, characterized in that The molar mass ratio of the magnesium salt to the metal ion is 1:0.01-5.

4. The rechargeable magnesium ion battery according to claim 1, wherein In step 1 of method B, the metal is selected from chromium, manganese, iron, cobalt, nickel, copper, zinc, and silver, and the metal is a corresponding metal sheet.

5. A method for preparing a rechargeable magnesium ion battery according to any one of claims 1 to 4, comprising: The active material, conductive agent and binder of the positive electrode are mixed, a solvent is added dropwise and then ball-milled to obtain a homogenous slurry, which is then coated on a positive electrode current collector and dried to remove the solvent to prepare a positive electrode sheet; the positive electrode current collector is selected from one of copper, aluminum, stainless steel, nickel, molybdenum, Hastelloy, titanium and carbon, The active material, conductive agent and binder of the negative electrode are mixed, a solvent is added dropwise and then ball-milled to obtain a homogenous slurry, which is then coated on a negative electrode current collector and dried to remove the solvent to prepare a negative electrode sheet; the negative electrode current collector is selected from one of copper, aluminum, stainless steel, nickel, molybdenum, Hastelloy, titanium and carbon, The prepared positive electrode sheet, negative electrode sheet, electrolyte and separator are assembled into a battery.

6. A rechargeable magnesium ion battery comprising a battery case, a positive electrode, a negative electrode, a separator between the positive electrode and the negative electrode, and an electrolyte containing a magnesium salt, characterized in that: There is a metal interlayer between the positive electrode and the separator, and / or there is a metal interlayer between the negative electrode and the separator, and the metal interlayer is a metal sheet selected from chromium, manganese, iron, cobalt, nickel, copper, zinc, and silver.

7. The method for preparing the rechargeable magnesium ion battery according to claim 6, comprising: The active material, conductive agent and binder of the positive electrode are mixed, a solvent is added dropwise and then ball-milled to obtain a homogenous slurry, which is then coated on a positive electrode current collector and dried to remove the solvent to prepare a positive electrode sheet; the positive electrode current collector is selected from one of copper, aluminum, stainless steel, nickel, molybdenum, Hastelloy, titanium and carbon, The active material, conductive agent and binder of the negative electrode are mixed, a solvent is added dropwise and then ball-milled to obtain a homogenous slurry, which is then coated on a negative electrode current collector and dried to remove the solvent to prepare a negative electrode sheet; the negative electrode current collector is selected from one of copper, aluminum, stainless steel, nickel, molybdenum, Hastelloy, titanium and carbon, The prepared positive electrode sheet, negative electrode sheet, electrolyte, separator and metal interlayer are assembled into a battery.

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