Organic magnesium-potassium mixed ion electrolyte and magnesium-potassium mixed ion battery

Abstract

The present invention provides an organic magnesium-potassium mixed ion electrolyte, which belongs to the field of rechargeable battery technology. The electrolyte contains a magnesium salt electrolyte, a potassium salt electrolyte, an amino organic solvent and an ether organic solvent; in the electrolyte, the concentration of the magnesium salt electrolyte is 0.1-1.0 mol / L, and the concentration of the potassium salt electrolyte is 0.1-1.0 mol / L; the magnesium salt electrolyte includes at least one of Mg(TFSI)2, Mg(PF6)2, Mg(OTf)2 and Mg(BF4)2; the potassium salt electrolyte includes at least one of KFSI, KPF6, KTFSI and KOTf. The electrolyte introduces monovalent metal ion potassium, which can achieve synergistic intercalation of magnesium ions and potassium ions, promote the insertion / extraction of magnesium ions in layered oxides, and the organic magnesium-potassium mixed ion electrolyte has good compatibility with magnesium metal, and magnesium metal or magnesium alloy can be used as the negative electrode material of the mixed ion battery, thereby improving the battery energy density and long cycle life. The present invention also provides a magnesium-potassium mixed ion battery.

Description

Technical Field

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

[0002] Rechargeable batteries are an important energy storage device that can be used to store intermittent energy generated by renewable energy sources such as solar energy and wind energy. Among them, lithium-ion battery (LI B) technology is considered to be one of the best existing energy storage technologies in the field of rechargeable batteries, with high energy density and excellent long-term cycle performance. Due to the explosive growth in demand for lithium-ion batteries, lithium-ion batteries obviously have the disadvantages of insufficient abundance in the earth's crust and difficulty in mining and use. In addition, the safety issues caused by uncontrollable lithium dendrite growth have also seriously hindered the development of lithium-ion batteries. Therefore, researchers have turned their attention to magnesium-ion batteries, zinc-ion batteries, calcium-ion batteries and other multivalent metal battery systems that are more abundant in resources, more environmentally friendly and have higher energy density. Among them, rechargeable magnesium-ion batteries (RMBs) have a higher volumetric capacity (the volumetric capacity of magnesium is 3833mAh·cm -3 , almost twice that of lithium, 2062mAh·cm -3 ), in most cases, it has no dendrites, low redox potential, abundant resources and other advantages, making it one of the most promising batteries in the post-lithium era.

[0003] Although magnesium ion batteries have many advantages, the lack of suitable magnesium ion battery cathode materials has limited the development of high-performance magnesium batteries. + and Na + In contrast, due to the divalent nature of magnesium ions, Mg 2+ The electrostatic interaction between the cathode material and the cathode material is stronger, which increases the reaction energy barrier and slows down the Mg 2+ The diffusion dynamics of the layered cathode material leads to unsatisfactory electrochemical performance. In addition, during the charge and discharge process of the layered cathode material, the valence state of the transition metal changes with the insertion / deinsertion of metal ions between the layers. Among them, the manganese-based compounds have a strong electrochemical performance. 3+ Ions are prone to Jahn-Te l ler distortion and disproportionation reaction (2Mn 3+ →Mn 2+ +Mn 4+ ), resulting in the elongation of the Mn-O bond and the 2+ The dissolution of the electrolyte causes serious volume changes in the overall structure, resulting in structural instability, which in turn affects the cycle stability of the battery.

[0004] In recent years, magnesium-ion hybrid batteries, including magnesium-lithium hybrid batteries and magnesium-sodium hybrid batteries, have received widespread attention. However, reports on magnesium-potassium hybrid batteries are relatively rare. This is due to a lack of suitable cathode materials that can achieve reversible insertion and extraction of magnesium and potassium ions, and a lack of organic magnesium-potassium hybrid electrolytes that can be used with magnesium metal anodes. Furthermore, traditional mixed-ion electrolytes are often accompanied by solvent and electrolyte decomposition, corrosion, and passivation during cycling, making it difficult to fully utilize the advantages of high energy density and long life of mixed-ion battery systems.

[0005] For example, the invention patent "Sodium-magnesium hybrid battery of P2 phase layered oxide positive electrode material and its preparation method and application" prepared a P2 phase layered oxide positive electrode material, whose chemical formula is Na x Mn y M z O 2-δ The invention also provides a preparation method and application of sodium-magnesium hybrid battery with P2 phase layered oxide positive electrode material. 2+ Due to the strong electrostatic attraction between the surrounding atoms, the diffusion in the solid phase material is slow and the kinetic performance is poor. In addition, due to the influence of the Jan-Taylor effect, the cycle performance of the manganese-based layered oxide positive electrode material is poor. Therefore, Mg in magnesium batteries 2+ Poor diffusion kinetics and poor structural stability are the current problems. According to the nomenclature proposed by Delmas et al., the letters P and O represent the prismatic or octahedral coordination environment of the alkali metal site, respectively, and the numbers 2 and 3 represent the number of repeated TMO2 layers in a single unit cell. x Among TMO2 oxides, the P2 structure seems to be suitable as a positive electrode material for long cycle life testing. However, in actual applications, the narrow TMO2 interlayer spacing makes it difficult for ions to insert / eject between the layers, which seriously limits the battery's rate performance and cycle stability.

[0006] The patent "Porous Sheet-Shaped Nickel Selenide Nanomaterial and Preparation Method, Aqueous Lithium / Magnesium Mixed Ion Electrolyte, and Lithium / Magnesium Mixed Ion Battery" prepares an aqueous lithium-magnesium mixed electrolyte and a lithium / magnesium mixed ion battery. In aqueous lithium-magnesium mixed ion batteries, the designed aqueous lithium-magnesium mixed ion electrolyte passivates the magnesium metal negative electrode, making it impossible to use magnesium metal and its alloys as the battery's negative electrode. This negates the advantage of magnesium metal and its alloys as direct negative electrodes for magnesium batteries, making it difficult to fully utilize the high volumetric energy density of the magnesium metal negative electrode. Summary of the Invention

[0007] In order to obtain a new type of magnesium-potassium mixed ion battery, the present invention provides an organic magnesium-potassium mixed ion electrolyte. The electrolyte introduces the monovalent metal ion potassium, which can achieve synergistic intercalation of magnesium ions and potassium ions, promote the insertion / extraction of magnesium ions in layered oxides, and the organic magnesium-potassium mixed ion electrolyte has good compatibility with magnesium metal. Magnesium metal or magnesium alloy can be used as the negative electrode material of the mixed ion battery, thereby improving the battery energy density and extending the cycle life.

[0008] The present invention also provides a magnesium-potassium mixed ion battery.

[0009] The present invention is achieved through the following technical solutions:

[0010] The present invention provides an organic magnesium-potassium mixed ion electrolyte, wherein the electrolyte comprises a magnesium salt electrolyte, a potassium salt electrolyte, an amino organic solvent and an ether organic solvent;

[0011] In the electrolyte, the concentration of the magnesium salt electrolyte is 0.1-1.0 mol / L, and the concentration of the potassium salt electrolyte is 0.1-1.0 mol / L;

[0012] The magnesium salt electrolyte includes at least one of Mg(TFSI)2, Mg(PF6)2, Mg(OTf)2 and Mg(BF4)2 (magnesium tetrafluoroborate);

[0013] The potassium salt electrolyte includes at least one of KFSI, KPF6, KTFSI and KOTf (potassium trifluoromethanesulfonate).

[0014] Furthermore, the amino-based organic solvent includes at least one of 1-methoxy-2-propylamine, 2-methoxyethylamine, 3-methoxypropylamine, ethylenediamine and bis(2-methoxyethyl)amine;

[0015] The ether organic solvent includes at least one of tetrahydrofuran (THF), DME (ethylene glycol dimethyl ether), G2 (diethylene glycol dimethyl ether), G3 (triethylene glycol dimethyl ether) and G4 (tetraethylene glycol dimethyl ether).

[0016] Furthermore, the mass ratio of the amino organic solvent to the ether organic solvent is 5:1 to 1:5.

[0017] Based on the same inventive concept, the present invention provides a method for preparing an organic magnesium potassium mixed ion electrolyte, the preparation method comprising:

[0018] Mixing an amino organic solvent and an ether organic solvent to obtain a mixed solvent;

[0019] A magnesium salt electrolyte and a potassium salt electrolyte are dissolved together in the mixed solvent to obtain an organic magnesium potassium mixed ion electrolyte.

[0020] Based on the same inventive concept, the present invention provides an application of an organic magnesium-potassium mixed ion electrolyte in the preparation of a magnesium-potassium mixed ion battery.

[0021] Based on the same inventive concept, the present invention provides a magnesium-potassium mixed ion battery, which contains the above-mentioned organic magnesium-potassium mixed ion electrolyte.

[0022] Based on the same inventive concept, the present invention also provides a magnesium-potassium mixed ion battery, which uses magnesium metal or magnesium alloy as the negative electrode, a Mn composite material as the positive electrode, a glass fiber membrane as the separator, and the above-mentioned organic magnesium-potassium mixed ion electrolyte as the electrolyte.

[0023] Furthermore, the raw materials for preparing the Mn composite material include K x MnO2 positive electrode material, conductive agent and binder, and K x The mass ratio of MnO2 positive electrode material, conductive agent and binder is 7:2:1;

[0024] The conductive agent includes at least one of graphene, Super P, Ketjen black and acetylene black;

[0025] The binder includes at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyacrylic acid (PAA).

[0026] Furthermore, the positive electrode is prepared by the following method:

[0027] The potassium salt and the manganese salt are mixed and ball-milled in a certain molar ratio to obtain a powdered precursor;

[0028] The powdered precursor is calcined to obtain K x MnO2 cathode material;

[0029] The K x The MnO2 positive electrode material is mixed with a conductive agent and a binder, and then an organic solvent is added to prepare a slurry;

[0030] The slurry is coated on a current collector and dried to obtain a positive electrode sheet.

[0031] Preferably, the molar ratio of the potassium salt to the manganese salt is 1:2;

[0032] The potassium salt includes potassium carbonate, and the manganese salt includes manganese trioxide;

[0033] The calcination temperature of the powdered precursor is 900±50° C., and the calcination time is 12±2 hours.

[0034] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0035] 1. The present invention discloses an organic magnesium-potassium mixed ion electrolyte. Compared with a single magnesium ion electrolyte, the electrolyte of the present invention introduces a monovalent metal ion potassium, which can achieve synergistic intercalation of magnesium ions and potassium ions, and promote the insertion / extraction of magnesium ions in layered oxides. In addition, unlike the passivation of magnesium metal by aqueous magnesium battery electrolytes, the organic magnesium-potassium mixed ion electrolyte of the present invention has good compatibility with magnesium metal, and magnesium foil or magnesium alloy can be used as the negative electrode material of the mixed ion battery, so that the mixed ion battery can have a higher energy density and a longer cycle life.

[0036] 2. The present invention discloses an organic magnesium-potassium mixed ion electrolyte. This electrolyte adopts a mixed solvent of an amino organic solvent and an ether organic solvent from the perspective of solvent regulation. The mixed solvent is a solvent with a molecular structure similar to that of traditional DME. This mixed solvent can change the desolvation energy of the solvated magnesium ions on the negative electrode side, promote the interfacial charge transfer kinetics, thereby improving the electrochemical performance of the ion battery and solving the problem of mismatch between the electrolyte and the magnesium metal negative electrode.

[0037] 3. The present invention relates to a magnesium-potassium mixed ion battery, which uses magnesium metal or magnesium alloy as the negative electrode, a Mn composite material as the positive electrode, and an organic magnesium-potassium mixed ion electrolyte as the electrolyte. The P3 type K x MnO2 has a typical layered structure, and its large interlayer distance can weaken the Mg 2+ The electrostatic interaction with the surrounding atoms is Mg 2+ The diffusion migration provides enough space to reduce the reaction energy barrier, thereby improving the ionic conductivity and accelerating the Mg 2+ The diffusion dynamics of the magnesium ion battery can be improved, and the cyclic stability of the material during the cycle can be improved. The magnesium-potassium mixed ion battery of the present invention can realize the synergistic energy storage of magnesium ions and potassium ions in a mixed system, and has a significant improvement in capacity and cycle performance compared to a single magnesium ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 is the SEM image of KMO prepared in Example 1;

[0040] Figure 2TEM image of KMO prepared in Example 1;

[0041] Figure 3 This is the charge-discharge curve of the KMO positive electrode material in the mixed ion electrolyte of Example 1 for the 10th cycle;

[0042] Figure 4 This is the long cycle curve of the KMO cathode material in the mixed ion electrolyte of Example 2;

[0043] Figure 5 The charge and discharge curves of the KMO positive electrode material in the magnesium battery electrolyte in Comparative Example 1 for the first 50 cycles;

[0044] Figure 6 This is the charge-discharge curve of the first 20 cycles of the KMO positive electrode material in the magnesium-potassium mixed ion electrolyte without amine solvent in Comparative Example 2. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below in conjunction with specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific embodiments and examples are for illustrating the present invention, rather than for limiting the present invention.

[0046] Throughout this specification, unless otherwise specified, the terms used herein should be understood as having the same meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the event of any conflict, the present specification shall take precedence.

[0047] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0048] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0049] The technical principles of the present invention are as follows:

[0050] Layered transition metal oxides have unique structural advantages that meet the requirements of Mg 2+ Insertion requirements, high theoretical specific capacity, simple synthesis, have great development potential in RMBs, especially manganese-based layered oxides, which have been widely studied due to their low cost and environmentally friendly characteristics. Although magnesium-ion batteries have many advantages, the lack of suitable magnesium-ion battery positive electrode materials has limited the development of high-performance magnesium batteries. This is because: Compared with monovalent Li + and Na + In contrast, due to the divalent nature of magnesium ions, Mg 2+The electrostatic interaction between the cathode material and the cathode material is stronger, which increases the reaction energy barrier and slows down the Mg 2+ The diffusion dynamics of Mg(TFSI)2 lead to unsatisfactory electrochemical performance. In addition, in traditional electrolyte systems, the decomposition of electrolyte solvents such as ethylene glycol dimethyl ether (DME) or electrolyte salts such as Mg(TFSI)2 and the solvation of Mg(TFSI)2 in the electrolyte are also important. 2+ Difficulty in removing solvents also leads to poor electrochemical performance. In addition, during the charge and discharge process of the positive electrode material, as the alkali metal ions are embedded / deintercalated between the layers, the valence state of the transition metal also changes. 3+ Ions are prone to Jahn-Te l ler distortion and disproportionation reaction (2Mn 3+ →Mn 2+ +Mn 4+ ), resulting in the elongation of the Mn-O bond and the 2+ The dissolution of the layered oxides causes a serious volume change in the overall structure, leading to structural instability and affecting the cycle stability of the battery. Therefore, the development of new and stable layered oxide cathode materials is of great significance to the development of magnesium-ion batteries.

[0051] Typically, Mg 2+ The reasons for the slow diffusion in the cathode are: (1) Mg 2+ The transport at the liquid-solid interface is slow, that is, the solvated Mg 2+ The desolvation process is difficult, resulting in Mg 2+ Cannot diffuse quickly into the interior of the material; (2) Mg 2+ Diffusion in the bulk material is slow, that is, divalent Mg 2+ There is a strong mutual attraction between Mg and the surrounding atoms. 2+ Slow diffusion in bulk materials has long been a problem. Commonly used strategies include pre-embedding organic / inorganic small molecules to expand the interlayer distance. However, the cathode materials prepared by this type of method are thermodynamically unstable, and the layered structure is not easy to maintain during the cycle, which may lead to poor cycle stability.

[0052] Generally speaking, modified electrolyte is a solution for Mg 2+ An effective means of slowing down the diffusion at the interface. Recent studies have shown that the interface dynamics behavior is affected by Mg 2+ The inventors found that the introduction of methoxyethylamine additives into the traditional Mg(TFSI)2 salt / ether electrolyte made the magnesium metal negative electrode highly reversible through the solvation sheath reorganization. This solvation sheath reorganization not only bypassed the unfavorable desolvation process, but also achieved Mg 2+ Rapid diffusion at the interface is beneficial for suppressing the decomposition of solvent / electrolyte salt.

[0053] Based on this, the present invention proposes an organic magnesium-potassium mixed ion electrolyte and battery. From the perspective of solvent regulation, the electrolyte adopts a mixed solvent of an amino organic solvent and an ether solvent, which changes the desolvation energy of the solvated magnesium ions on the negative electrode side, promotes the interfacial charge transfer kinetics, solves the problem of mismatch between the electrolyte and the magnesium metal negative electrode, and inhibits the decomposition of the solvent / electrolyte salt.

[0054] The magnesium-potassium mixed ion battery of the present invention adopts a positive electrode material containing K x MnO2, with alkali metal ions K having a larger ionic radius + Replaced Na + , while achieving thermodynamic stability and expanding the intrinsic interlayer spacing, thereby increasing the Mg 2+ Diffusion rate in bulk material. x MnO2 has a typical layered structure, and its large interlayer distance can weaken the Mg 2+ The electrostatic interaction with the surrounding atoms is Mg 2+ The diffusion migration of Mg provides enough space to improve the ionic conductivity and accelerate the 2+ The diffusion dynamics of the material can be improved and the cycling stability of the material can be enhanced during the cycling process.

[0055] Specifically, the present invention provides an organic magnesium-potassium mixed ion electrolyte, wherein the electrolyte comprises a magnesium salt electrolyte, a potassium salt electrolyte, an amino organic solvent, and an ether organic solvent;

[0056] In the electrolyte, the concentration of the magnesium salt electrolyte is 0.1-1.0 mol / L, and the concentration of the potassium salt electrolyte is 0.1-1.0 mol / L;

[0057] The magnesium salt electrolyte includes at least one of Mg(TFSI)2, Mg(PF6)2, Mg(OTf)2 and Mg(BF4)2;

[0058] The potassium salt electrolyte includes at least one of KFSI, KPF6, KTFSI and KOTf.

[0059] In the present invention, the concentration of the magnesium salt electrolyte in the electrolyte is 0.1-1.0 mol / L. Within this concentration range, the electrolyte has a high ion diffusion rate and a suitable viscosity, ensuring rapid ion diffusion. If the electrolyte concentration is too low, it may lead to low ion conductivity. If the concentration is too high, on the one hand, it will generate higher costs, and on the other hand, it will increase the viscosity of the electrolyte, which is not conducive to ion diffusion.

[0060] In the present invention, the concentration of the potassium salt electrolyte in the electrolyte is 0.1-1.0 mol / L. Within this concentration range, the electrolyte has a high ion diffusion rate and a suitable viscosity, ensuring rapid ion diffusion. If the electrolyte concentration is too low, it may lead to low ion conductivity. If the concentration is too high, on the one hand, it will generate higher costs, and on the other hand, it will increase the viscosity of the electrolyte, which is not conducive to ion diffusion.

[0061] In the present invention, the magnesium salt electrolyte uses at least one of Mg(TFSI)2, Mg(PF6)2, Mg(OTf)2, and Mg(BF4)2, all of which are common magnesium salts in magnesium batteries and are easily soluble in solvents commonly used in magnesium batteries. The potassium salt electrolyte uses at least one of KFSI, KPF6, KTFSI, and KOTf, all of which are common potassium salts in potassium batteries and are easily soluble in solvents commonly used in potassium batteries.

[0062] Furthermore, the amino-based organic solvent includes at least one of 1-methoxy-2-propylamine, 2-methoxyethylamine, 3-methoxypropylamine, ethylenediamine and bis(2-methoxyethyl)amine;

[0063] The ether organic solvent includes at least one of tetrahydrofuran, DME, G2, G3 and G4.

[0064] Furthermore, the mass ratio of the amino organic solvent to the ether organic solvent is 5:1 to 1:5.

[0065] In the present invention, the mass ratio of the amino organic solvent to the ether organic solvent is 5:1 to 1:5, which has the advantage that the addition amount of the amine solvent is moderate, which can improve the solvation structure of the magnesium ion, promote the diffusion of the cation, and reduce the decomposition of the anion.

[0066] Based on the same inventive concept, the present invention provides a magnesium-potassium mixed ion battery, which uses magnesium metal or magnesium alloy as the negative electrode, a Mn composite material as the positive electrode, a glass fiber membrane as the separator, and the above-mentioned organic magnesium-potassium mixed ion electrolyte as the electrolyte.

[0067] Furthermore, the raw materials for preparing the Mn composite material include K x MnO2 positive electrode material, conductive agent and binder, and K x The mass ratio of MnO2 positive electrode material, conductive agent and binder is 7:2:1;

[0068] The conductive agent includes at least one of graphene, Super P, Ketjen black and acetylene black;

[0069] The binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene and polyacrylic acid.

[0070] Furthermore, the positive electrode is prepared by the following method:

[0071] The potassium salt and the manganese salt are mixed and ball-milled in a certain molar ratio to obtain a powdered precursor;

[0072] The powdered precursor is calcined to obtain K x MnO2 cathode material;

[0073] The K x The MnO2 positive electrode material is mixed with a conductive agent and a binder, and then an organic solvent is added to prepare a slurry;

[0074] The slurry is coated on a current collector and dried to obtain a positive electrode sheet.

[0075] Preferably, the molar ratio of the potassium salt to the manganese salt is 1:2;

[0076] The potassium salt includes potassium carbonate, and the manganese salt includes manganese trioxide;

[0077] The calcination temperature of the powdered precursor is 900±50° C., and the calcination time is 12±2 hours.

[0078] In the present invention, the potassium salt is potassium carbonate, and the manganese salt is manganese trioxide. The advantages are low cost, safety, reliability, and abundant raw materials. On the one hand, the synthesis process is simple, and on the other hand, the battery cost is reduced.

[0079] The organic magnesium-potassium mixed ion electrolyte and the magnesium-potassium mixed ion battery of the present invention are described in detail below with reference to the examples and experimental data.

[0080] Example 1

[0081] A method for preparing a positive electrode material for a magnesium-potassium mixed ion battery comprises the following steps:

[0082] (1) Potassium carbonate and manganese trioxide in a stoichiometric ratio (1:2) are mixed to form a precursor, and the precursor is placed in a ball mill and ground at high speed for four hours to obtain a powdered precursor;

[0083] (2) After the powdery precursor is pressed into a sheet precursor, the temperature is raised from room temperature to 900°C in a muffle furnace at a heating rate of 5°C / min, and heat-treated in an air atmosphere for 12 hours; after natural cooling, the obtained product is taken out and rapidly ground in a mortar for 5 to 10 minutes to obtain a P3 phase layered oxide magnesium potassium mixed ion battery positive electrode material K 0.5 MnO2.

[0084] The SEM image of the prepared magnesium-potassium mixed ion battery positive electrode material is shown in Figure 1 As shown, the synthesized K 0.5MnO2 has a uniform lamellar structure and the particle size is 2-5μm. Figure 2 This is the TEM image of the prepared magnesium-potassium mixed ion battery positive electrode material. Obvious lattice fringes can be seen from the TEM image, and the layer spacing is large, about 0.64nm.

[0085] A method for preparing an organic magnesium-potassium mixed ion electrolyte comprises the following steps:

[0086] In this embodiment, the magnesium salt electrolyte selected is Mg(TFSI)2, the potassium salt electrolyte is KTFSI, the ether organic solvent is DME (ethylene glycol dimethyl ether), and the amine organic solvent is 2-methoxyethylamine. The concentrations of the magnesium salt and potassium salt in the mixed electrolyte are each 0.5 mol / L. The preparation method includes the following steps:

[0087] (1) adding 4A molecular sieves to dry DME (ethylene glycol dimethyl ether) and 2-methoxyethylamine solvents (wherein the mass ratio of DME to 2-methoxyethylamine is 4.7:1);

[0088] (2) Weigh a certain amount of the above magnesium salt and potassium salt and transfer them to a clean bottle. Calculate the amount of each solvent required based on the mass of the weighed salts. Then, use a pipette to accurately measure the required amount of each solvent and add it to the bottle containing the mixed electrolyte salt to prepare the desired mixed ion electrolyte solution. The prepared electrolyte solution is stirred at room temperature using a magnetic stirrer for at least 12 hours until all the electrolyte salts are dissolved, obtaining a clear magnesium-potassium mixed ion electrolyte solution.

[0089] A preparation method of a magnesium-potassium mixed ion battery, the specific preparation method is:

[0090] The positive electrode material K prepared in Example 1 0.5 MnO2, magnesium potassium mixed ion electrolyte, GF-A glass fiber separator and polished magnesium foil were assembled into CR2032 button batteries: 0.5 MnO2 powder was uniformly mixed with the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 70:20:10, and a certain amount of N-methylpyrrolidone (NMP) solution was added to prepare a slurry in a room temperature dry environment. The slurry was then evenly coated on the current collector aluminum (Al) foil and cut into pole pieces with a diameter of 12 mm. After vacuum drying for 12 hours, the pole pieces were assembled with polished magnesium foil, GF-A glass fiber separator, and 100 μL of the mixed ion electrolyte in Example 1 to form a magnesium-potassium hybrid battery. The entire battery assembly process was carried out in a glove box filled with argon protection. Figure 3 The hybrid ion battery assembled for this example was -1 The charge and discharge curve of the 10th cycle under current shows higher capacity and high coulombic efficiency.

[0091] Example 2

[0092] A method for preparing a positive electrode material for a magnesium-potassium mixed ion battery comprises the following steps:

[0093] (1) Potassium carbonate and manganese trioxide in a stoichiometric ratio of 1:2 are mixed to form a precursor, and the precursor is placed in a ball mill and ground at high speed for four hours to obtain a powdered precursor;

[0094] (2) After the powdery precursor is pressed into a sheet precursor, the temperature is raised from room temperature to 900°C in a muffle furnace at a heating rate of 5°C / min, and heat-treated in an air atmosphere for 12 hours; after natural cooling, the obtained product is taken out and quickly ground in a mortar for 5 to 10 minutes to obtain a P3 phase layered oxide magnesium potassium mixed ion battery positive electrode material K 0.5 MnO2.

[0095] A method for preparing an organic magnesium-potassium mixed ion electrolyte comprises the following steps:

[0096] In this embodiment, the magnesium salt electrolyte selected is Mg(TFSI)2, the potassium salt electrolyte is KTFSI, the ether organic solvent is DME (ethylene glycol dimethyl ether), and the amine organic solvent is 3-methoxypropylamine. The concentrations of the magnesium salt and potassium salt in the mixed electrolyte are each 0.5 mol / L. The preparation method includes the following steps:

[0097] (1) adding 4A molecular sieves to dry DME (ethylene glycol dimethyl ether) and 3-methoxypropylamine solvents (wherein the mass ratio of DME to 3-methoxypropylamine is 4.67:1);

[0098] (2) Weigh a certain amount of the above magnesium salt and potassium salt and transfer them to a clean bottle. Calculate the amount of each solvent required based on the mass of the weighed salts. Then, use a pipette to accurately measure the required amount of each solvent and add it to the bottle containing the mixed electrolyte salt to prepare the desired mixed ion electrolyte solution. The prepared electrolyte solution is stirred at room temperature using a magnetic stirrer for at least 12 hours until all the electrolyte salts are dissolved, obtaining a clear magnesium-potassium mixed ion electrolyte solution.

[0099] A preparation method of a magnesium-potassium mixed ion battery, the specific preparation method is:

[0100] The positive electrode material K prepared in Example 2 0.5 MnO2, magnesium potassium mixed ion electrolyte, GF-A glass fiber separator and polished magnesium foil were assembled into CR2032 button batteries: 0.5MnO2 powder was evenly mixed with the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 70:20:10, and a certain amount of N-methylpyrrolidone (NMP) solution was added to prepare a slurry in a room temperature dry environment. The slurry was then evenly coated on the current collector aluminum (Al) foil and cut into pole pieces with a diameter of 12 mm. After vacuum drying for 12 hours, the pole pieces were assembled with polished magnesium foil, GF-A glass fiber separator, and 100 μL of the mixed ion electrolyte in Example 2 to form a magnesium-potassium hybrid battery. The entire battery assembly process was carried out in a glove box filled with argon protection. Figure 4 The cycle curve of the hybrid ion battery assembled in this embodiment shows its excellent cycle stability and high coulombic efficiency.

[0101] Comparative Example 1

[0102] A method for preparing a magnesium battery positive electrode material comprises the following steps:

[0103] (1) Potassium carbonate and manganese trioxide are mixed in a stoichiometric ratio of 1:2 to form a precursor, and the precursor is placed in a ball mill and ground at high speed for four hours to obtain a powdered precursor;

[0104] (2) After the powder precursor is pressed into a sheet precursor, the temperature is raised from room temperature to 900°C in a muffle furnace at a rate of 5°C / min, and heat treated in an air atmosphere for 12 hours; after natural cooling, the obtained product is taken out and quickly ground in a mortar for 5 to 10 minutes to obtain a P3 phase layered oxide magnesium battery positive electrode material K 0.5 MnO2.

[0105] The prepared K 0.5 MnO2 powder is mixed with the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) in a mass ratio of 70:20:10. A certain amount of N-methylpyrrolidone (NMP) solution is added and ground in a dry environment at room temperature to form a slurry. The slurry is then evenly coated on the current collector molybdenum (Mo) foil and cut into 12mm diameter electrode pieces after drying. The cut electrode pieces are dried under vacuum conditions at 60°C for 12 hours and then transferred to a glove box for later use.

[0106] A method for preparing an organic magnesium battery electrolyte comprises the following steps:

[0107] The magnesium salt electrolyte selected in this comparative example is Mg(TFSI)2, the ether organic solvent is DME (ethylene glycol dimethyl ether), the amine organic solvent is 3-methoxypropylamine, and the concentration of the magnesium salt in the mixed electrolyte is 0.5 mol / L. The preparation method comprises the following steps:

[0108] (1) adding 4A molecular sieves to dry DME (ethylene glycol dimethyl ether) and 3-methoxypropylamine solvents (wherein the mass ratio of DME to 3-methoxypropylamine is 4.67:1);

[0109] (2) Weigh a certain amount of the above magnesium salt and transfer it to a clean bottle. Calculate the amount of each solvent required based on the mass of the weighed salt. Then, use a pipette to accurately measure the required amount of each solvent and add it to the bottle containing the electrolyte salt to prepare the required electrolyte solution. The prepared electrolyte solution is stirred at room temperature using a magnetic stirrer for at least 12 hours until all the electrolyte salt is dissolved, thereby obtaining a clear magnesium battery electrolyte solution.

[0110] The materials in Comparative Example 1 were assembled into a magnesium battery using the same battery assembly method as in Examples 1 and 2. Figure 5 The charge and discharge curves of the magnesium battery assembled in this comparative example show that, compared with Example 2, the mixed ion battery using the magnesium-potassium mixed electrolyte has better performance.

[0111] Comparative Example 2

[0112] The preparation method of the positive electrode material is consistent with that of the aforementioned Example 1;

[0113] The electrolyte does not contain amine organic solvents, and the specific preparation method is as follows:

[0114] In this comparative example, the magnesium salt electrolyte selected is Mg(TFSI)2, the potassium salt electrolyte is KTFSI, and the ether organic solvent is DME (ethylene glycol dimethyl ether). The concentrations of the magnesium salt and potassium salt in the mixed electrolyte are each 0.5 mol / L. The preparation method comprises the following steps:

[0115] (1) Add a certain amount of 4A molecular sieve to DME (ethylene glycol dimethyl ether) solvent for drying;

[0116] (2) Weigh a certain amount of the above magnesium salt and potassium salt and transfer them to a clean bottle. Calculate the amount of DME solvent required based on the mass of the weighed salts. Use a pipette to accurately measure the required amount of solvent and add it to the bottle containing the mixed electrolyte salt to prepare the desired mixed ion electrolyte. Stir the prepared electrolyte using a magnetic stirrer at room temperature for at least 12 hours until all the electrolyte salts are dissolved, obtaining a clear magnesium-potassium mixed ion electrolyte.

[0117] The assembly method of the hybrid ion battery is the same as that of the above embodiment, and the test results are as follows: Figure 6, it can be seen that without the assistance of amine solvents, the hybrid ion battery using a simple Mg(TFSI)2-KTFSI-DME electrolyte cannot cycle normally. Finally, it should be noted that the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or apparatus.

[0118] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0119] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An organic magnesium potassium mixed ion electrolyte, characterized in that The electrolyte comprises a magnesium salt electrolyte, a potassium salt electrolyte, an amino organic solvent and an ether organic solvent; In the electrolyte, the concentration of the magnesium salt electrolyte is 0.1-1.0 mol / L, and the concentration of the potassium salt electrolyte is 0.1-1.0 mol / L; The magnesium salt electrolyte includes at least one of Mg(TFSI)2, Mg(PF6)2, Mg(OTf)2 and Mg(BF4)2; The potassium salt electrolyte includes at least one of KFSI, KPF6, KTFSI and KOTf.

2. An organic magnesium potassium mixed ion electrolyte according to claim 1, characterized in that The amino organic solvent includes at least one of 1-methoxy-2-propylamine, 2-methoxyethylamine, 3-methoxypropylamine, ethylenediamine and bis(2-methoxyethyl)amine; The ether organic solvent includes at least one of tetrahydrofuran, DME, G2, G3 and G4.

3. An organic magnesium potassium mixed ion electrolyte according to claim 1 or 2, characterized in that The mass ratio of the amino organic solvent to the ether organic solvent is 5:1 to 1:

5.

4. A method for preparing an organic magnesium potassium mixed ion electrolyte according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Mixing an amino organic solvent and an ether organic solvent to obtain a mixed solvent; A magnesium salt electrolyte and a potassium salt electrolyte are dissolved together in the mixed solvent to obtain an organic magnesium potassium mixed ion electrolyte.

5. Use of an organic magnesium-potassium mixed ion electrolyte according to any one of claims 1 to 3 in the preparation of a magnesium-potassium mixed ion battery.

6. A magnesium-potassium mixed ion battery, characterized in that: The magnesium-potassium mixed ion battery contains an organic magnesium-potassium mixed ion electrolyte according to any one of claims 1 to 3.

7. A magnesium-potassium mixed ion battery, characterized in that: The magnesium-potassium mixed ion battery uses magnesium metal or magnesium alloy as the negative electrode, a Mn composite material as the positive electrode, a glass fiber membrane as the separator, and an organic magnesium-potassium mixed ion electrolyte according to any one of claims 1 to 3 as the electrolyte.

8. A magnesium-potassium mixed ion battery according to claim 7, characterized in that: The raw materials for preparing the Mn composite material include K x MnO2 positive electrode material, conductive agent and binder, and K x The mass ratio of MnO2 positive electrode material, conductive agent and binder is 7:2:1; The conductive agent includes at least one of graphene, Super P, Ketjen black and acetylene black; The binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene and polyacrylic acid.

9. The magnesium-potassium mixed ion battery according to claim 7, characterized in that: The positive electrode is prepared by the following method: The potassium salt and the manganese salt are mixed and ball-milled in a certain molar ratio to obtain a powdered precursor; The powdered precursor is calcined to obtain K x MnO2 cathode material; The K x The MnO2 positive electrode material is mixed with a conductive agent and a binder, and then an organic solvent is added to prepare a slurry; The slurry is coated on a current collector and dried to obtain a positive electrode sheet.

10. The magnesium-potassium mixed ion battery according to claim 9, characterized in that: The molar ratio of the potassium salt to the manganese salt is 1:2; The potassium salt includes potassium carbonate, and the manganese salt includes manganese trioxide; The calcination temperature of the powdered precursor is 900±50° C., and the calcination time is 12±2 hours.

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