Magnesium anode with composite interfacial film surface modification and preparation method and application thereof, and rechargeable magnesium ion battery comprising same

Abstract

The application belongs to the field of magnesium ion batteries. A magnesium negative electrode with a composite interface film surface modification comprises a magnesium negative electrode, and the surface of the magnesium negative electrode is modified with a polyaniline / silver compound composite interface film. The application forms an artificial interface layer on the surface of the magnesium negative electrode by using a polyaniline solution first, and then treats the surface of the magnesium negative electrode with a silver compound solution to construct a thin and dense composite interface film on the surface of the magnesium negative electrode. The composite interface film can make the ion conduction of the magnesium metal surface uniform, provide a buffer area for ions, improve the efficiency and uniformity of magnesium ion deposition / peeling, inhibit the growth of magnesium dendrites, and improve the rate performance and cycle life of the magnesium ion battery. The application also provides a preparation method and application of the magnesium negative electrode with the composite interface film surface modification, and a rechargeable magnesium ion battery comprising the magnesium negative electrode with the composite interface film surface modification.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of magnesium ion batteries, and particularly relates to a magnesium negative electrode with surface modification of a composite interface film, a preparation method and application thereof, and a rechargeable magnesium ion battery comprising the same. BACKGROUND

[0002] With the global fossil resources becoming increasingly scarce year by year, people's demand for green energy has also increased, especially rechargeable batteries have become increasingly important. Rechargeable battery systems can store new energy and realize rational allocation of resources to reduce energy waste. Rechargeable lithium ion batteries are widely used in the fields of portable electronic devices and electric vehicles, but the problems of resource scarcity, high cost and poor safety restrict the further development of rechargeable lithium ion batteries in the field of large-scale energy storage.

[0003] Rechargeable magnesium batteries are generally composed of negative electrode materials, electrolytes and positive electrode materials, and their working principle is similar to that of lithium ion batteries / lithium metal batteries. When magnesium metal is used as the negative electrode material of rechargeable magnesium batteries, it is not easy to form magnesium dendritic deposition products due to the low diffusion barrier of magnesium, which ensures the safety of rechargeable battery systems. In addition, magnesium metal also has advantages such as high theoretical specific capacity (2205 mAh·g -1 ) and high theoretical volume capacity (3833 mAh·cm -3 ), and has attracted a lot of researchers' attention in recent years, and has strong potential as one of the next generation of advanced electrochemical energy storage technologies. Although magnesium metal is an ideal negative electrode material, due to the low reduction potential of magnesium metal (-2.37 V (vs. SHE)), it is easy to react in traditional electrolytes, forming an insulating surface passivation film, hindering the deposition / dissolution process of magnesium ions on the electrode surface, resulting in large polarization and low coulombic efficiency. If the magnesium deposition is uneven, it will cause three-dimensional growth of the deposition product or even dendritic growth, which poses a certain threat to the safety of the battery, and these problems seriously limit the development of rechargeable magnesium ion batteries.

[0004] In order to solve the problem of the formation of a passivation film on the surface of the magnesium metal negative electrode, break through the technical barriers of magnesium battery negative electrode failure and dendritic growth caused by uneven deposition / peeling of the Mg surface, and construct an artificial interface film on the surface of the magnesium metal negative electrode to achieve important breakthroughs in the cycle life, rate and other performances of rechargeable magnesium ion batteries, making them become a new generation of energy storage technology, which has important scientific significance. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a magnesium negative electrode with a composite interface film surface modification, solve the technical problem of incompatibility of magnesium metal and electrolyte interface, prevent the formation of passivation film, realize reversible magnesium ion deposition / dissolution, improve the efficiency and uniformity of magnesium ion deposition / peeling, inhibit the growth of magnesium dendrites, and improve the rate performance and cycle life of magnesium ion batteries.

[0006] The technical solution adopted by the present application to solve the above problems is as follows:

[0007] The magnesium negative electrode with a composite interface film surface modification comprises a magnesium negative electrode, and the surface of the magnesium negative electrode is modified with a polyaniline / silver compound composite interface film.

[0008] Further, the silver compound is at least one of silver nitrate, silver sulfate, silver halide, silver acetate, silver propionate, aromatic carboxylic acid silver, alkyl carboxylic acid silver salt, and nano silver powder.

[0009] The preparation method of the magnesium negative electrode with a composite interface film surface modification comprises the following steps:

[0010] S1. Pre-treating the surface of the magnesium negative electrode to remove surface impurities;

[0011] S2. Immersing the magnesium negative electrode pre-treated in step S1 in a polyaniline solution, performing ultrasonic treatment after immersion, and then taking out, washing, and drying;

[0012] S3. Immersing the magnesium negative electrode washed and dried in step S2 in a silver compound solution, performing ultrasonic treatment after immersion, and then taking out, washing, and drying to obtain the magnesium negative electrode with a composite interface film surface modification.

[0013] The polyaniline solution is a conductive polymer that can spontaneously react with magnesium metal to form a compound containing hydrogen bonds, ionic bonds, coordination bonds, etc. Immersing the magnesium negative electrode in the polyaniline solution can obtain a product with uniform thickness adsorbed on the surface of the magnesium metal, forming an organic artificial interface layer with thermodynamic stability and excellent kinetics. The further reaction of the silver compound on the modified artificial interface layer forms a composite interface film that is ion-conductive and electron-insulating. The composite interface film can homogenize the magnesium ion flux and prevent the aggregation of metal ions to form dendrites, thereby realizing a highly reversible and uniform deposition / peeling process during charging and discharging.

[0014] Further, in step S1, the pre-treatment is polishing and polishing the surface of the magnesium negative electrode, or chemically cleaning the surface of the magnesium negative electrode.

[0015] Further, in the step S2 and the step S3, the soaking time is 10-30 min.

[0016] Further, in the step S2 and the step S3, the ultrasonic time is 10-30 min.

[0017] Further, in the step S2 and the step S3, the drying is vacuum drying at 80℃. The vacuum drying can ensure that the composite interface film of the surface modification of the magnesium negative electrode is uniform, complete and without oxidation layer.

[0018] Further, the mass concentration of the polyaniline solution is 0.1%-10%, and the mass concentration of the silver compound solution is 0.1%-10%.

[0019] Further, the solvent in the polyaniline solution is one of N-methylpyrrolidone, DMSO and DMF.

[0020] The application further provides a rechargeable magnesium ion battery, which comprises a positive electrode material, a magnesium negative electrode with a composite interface film surface modification, a separator and an electrolyte.

[0021] Further, the separator is located between the positive electrode material and the magnesium negative electrode with a composite interface film surface modification, and the positive electrode material, the magnesium negative electrode with a composite interface film surface modification and the separator are impregnated with the electrolyte.

[0022] Further, the positive electrode material comprises a transition metal oxide.

[0023] Preferably, the positive electrode material comprises a magnesium-containing transition metal oxide.

[0024] Further, the electrolyte comprises an organic solvent, a conductive magnesium salt and an additive.

[0025] Further, the concentration of the conductive magnesium salt in the organic solvent is 0.2-2.0 mol / L, and the additive is added in an amount of 0.1-10% of the weight of the organic solvent.

[0026] Further, the organic solvent is at least one of organic ether, nitrile, carbonate and aromatic hydrocarbon compound.

[0027] Further, the conductive magnesium salt comprises Mg(AX 4-n R n )2, wherein A is one element of B, Al, Sb, Ta, Fe, As or P, X is one element of Cl, Br or F, and R is one of butyl group, ethyl group or phenyl group.

[0028] Further, the additive comprises a film-forming additive, and the film-forming additive is at least one of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propanesultone, butanesultone, adiponitrile, succinonitrile, LiBOB, and LiODFB.

[0029] Further, the film-forming additive is added in an amount of 0.1-5% of the total mass of the electrolyte.

[0030] Further, the upper limit voltage of the rechargeable magnesium ion battery is >3.0V.

[0031] The application also provides use of the magnesium negative electrode with the composite interface film surface modification in preparation of the rechargeable magnesium ion battery.

[0032] The application has the following beneficial effects:

[0033] The application forms an organic artificial interface layer with thermodynamic stability and excellent kinetics on the surface of the magnesium negative electrode by using a polyaniline solution, and then uses a silver compound solution to treat the surface of the magnesium negative electrode. The silver compound can form a cross-linked compound with the polymer, and the two build a thin, uniform and dense composite interface film on the surface of the magnesium negative electrode, improve the electrical conductivity of the polymer, and the introduction of inorganic compounds can enhance the rigidity of the interface film and improve the interface stability. The composite interface film can quantify the ion conduction amount on the surface of the magnesium metal, provide a buffer area for ions, improve the efficiency and uniformity of magnesium ion deposition / peeling, inhibit the growth of magnesium dendrites, and improve the rate performance and cycle life of the magnesium ion battery. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A galvanostatic polarization curve diagram of a Mg-Mg symmetric battery and a Mg-Mg symmetric battery with a composite interface film surface modification;

[0035] Figure 2 A SEM diagram of a fresh magnesium negative electrode without treatment and a magnesium negative electrode with a composite interface film surface modification of Example 1. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be clearly and completely described below in conjunction with specific embodiments. Unless otherwise specified, the test materials, reagents, methods and equipment used in the following examples are conventional test materials, reagents, methods and equipment in the technical field; unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial channels. In the quantitative test in the following examples, three repeated experiments are set, and the data are the average value or average value ± standard deviation of the three repeated experiments.

[0037] The present application provides a magnesium negative electrode surface modified by a composite interface film, comprising a magnesium negative electrode, and a polyaniline / silver compound composite interface film modified on the surface of the magnesium negative electrode.

[0038] In an embodiment, the silver compound is at least one of silver nitrate, silver sulfate, silver halide, silver acetate, silver propionate, silver aromatic carboxylate, silver alkyl carboxylate, and nano silver powder. The selection of the silver compound affects the ion conductivity, toughness and stability of the composite interface film.

[0039] The present application provides a preparation method of the magnesium negative electrode surface modified by the composite interface film, comprising the following steps:

[0040] S1. Pre-treating the surface of the magnesium negative electrode to remove surface impurities;

[0041] S2. Immersing the magnesium negative electrode pre-treated in step S1 in a polyaniline solution, performing ultrasonic treatment after the immersion, and then taking out, washing and drying;

[0042] S3. Immersing the magnesium negative electrode washed and dried in step S2 in a silver compound solution, performing ultrasonic treatment after the immersion, and then taking out, washing and drying to obtain the magnesium negative electrode surface modified by the composite interface film.

[0043] In an embodiment, the pre-treatment in step S1 is polishing and polishing the surface of the magnesium negative electrode; in another embodiment, the pre-treatment is chemically cleaning the surface of the magnesium negative electrode. The purpose of the pre-treatment is to remove oil stains and oxide films on the surface of the magnesium negative electrode.

[0044] In an embodiment, the immersion time in steps S2 and S3 is 10-30 min. The time can be arbitrarily selected within this range.

[0045] In an embodiment, the ultrasonic treatment time in steps S2 and S3 is 10-30 min. The time can be arbitrarily selected within this range.

[0046] In an embodiment, the drying in steps S2 and S3 is vacuum drying at a temperature of 80℃. Vacuum drying can ensure that the composite interface film modified on the surface of the magnesium negative electrode is uniform, complete and free of oxide layers.

[0047] In an embodiment, the mass concentration of the polyaniline solution is 0.1% to 10%, and the mass concentration of the silver compound solution is 0.1% to 10%. The mass concentrations of the polyaniline solution and the silver compound solution and the ratio therebetween affect the compactness, ion conductivity, electron insulation, and stability of the composite interface film.

[0048] In an embodiment, the solvent in the polyaniline solution can be one of N-methylpyrrolidone, DMSO, and DMF, but is not limited thereto.

[0049] The application also provides a rechargeable magnesium ion battery, which comprises a positive electrode material, a magnesium negative electrode surface-modified by the composite interface film, a separator, and an electrolyte.

[0050] In an embodiment, the separator is located between the positive electrode material and the magnesium negative electrode surface-modified by the composite interface film, and the positive electrode material, the magnesium negative electrode surface-modified by the composite interface film, and the separator are impregnated with the electrolyte.

[0051] In an embodiment, the positive electrode material comprises a transition metal oxide. In a preferred embodiment, the positive electrode material comprises a magnesium-containing transition metal oxide. As an example, specifically, the active material of the positive electrode is Mg2Mn2O4, Mg(Ni a Co b Mn c )O2(0<a<1,0<b<1,0<c<1,a+b+c=1),MgNi (1-y) Co y O2, MgCo (1-y) Mn y O2, MgNi (1-y) Mn y O2(0≤y<1), Mg(Ni a Co b Mn c )O4(0<a<2 ,0<b<2,0<c<2,a+b+c=2),MgM x (PO4) y (M is Ni, Co, Mn, Fe, Ti, or V, 0≤x≤5, 0≤y≤5), MoS, V2O5, Nb2O5, TiNb2O7, but is not limited thereto.

[0052] In an embodiment, the material of the separator is one of woven cloth, non-woven cloth, and synthetic resin microporous membrane, but is not limited thereto.

[0053] In an embodiment, the electrolyte comprises an organic solvent, a conductive magnesium salt, and an additive.

[0054] In an embodiment, the concentration of the conductive magnesium salt in the organic solvent is 0.2 to 2.0 mol / L, and the additive is added in an amount of 0.1% to 10% by weight of the organic solvent.

[0055] In an embodiment, the organic solvent is at least one of an organic ether, a nitrile, a carbonate, and an aromatic hydrocarbon.

[0056] As an example, specifically, the organic ether can be at least one of tetrahydrofuran, dimethylsulfoxyl oxide, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and fluoroether; the nitrile can be at least one of acetonitrile, butanedinitrile, propanedinitrile, hexanedinitrile, and isophthalonitrile; the carbonate can be at least one of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl acetate, methyl propyl carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate, γ-butyrolactone, and γ-valerolactone; and the aromatic hydrocarbon can be at least one of benzene, fluorobenzene, difluorobenzene, toluene, trifluorobenzene, and xylene.

[0057] In an embodiment, the conductive magnesium salt includes Mg(AX 4-n R n , wherein A is one of B, Al, Sb, Ta, Fe, As, and P, X is one of Cl, Br, and F, and R is one of a butyl group, an ethyl group, and a phenyl group.

[0058] In an embodiment, the conductive magnesium salt can further include at least one of Mg(TFSI)2, Mg(PF6)2, Mg(BF4)2, Mg(SO3CF3)2, Mg(ClO4)2, Mg((CF3SO2)2N)2, Mg(C(CF3SO2)3)2, an organic magnesium halogen aluminum salt complex (such as ethylmagnesium aluminum chloride or phenylmagnesium aluminum chloride), a boron magnesium compound salt, MgCl2, and ROMgCl, but is not limited thereto.

[0059] In an embodiment, the additive includes a film-forming additive, and the film-forming additive is at least one of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propanesultone, butanesultone, hexanedinitrile, butanedinitrile, LiBOB, and LiODFB.

[0060] In an embodiment, the film-forming additive is added in an amount of 0.1 to 5% of the total mass of the electrolyte.

[0061] In an embodiment, the rechargeable magnesium ion battery has an upper limit voltage of > 3.0 V.

[0062] The application also provides a use of the magnesium negative electrode with the surface of the composite interface film modified as described above in the preparation of a rechargeable magnesium ion battery.

[0063] The application will be further described in accordance with the examples and comparative examples. Obviously, the described examples are only a part of the examples of the application, rather than all the examples, and are not a limitation on the application. Based on the examples in the application, all other examples obtained by a person of ordinary skill in the art without making creative efforts fall within the scope of protection of the application.

[0064] The following Table 1 is the raw materials and amounts used in the preparation of the composite interface film surface modified magnesium negative electrode in the examples and comparative examples.

[0065] Table 1:

[0066]

[0067] The preparation method of the composite interface film surface modified magnesium negative electrode in the examples is as follows:

[0068] (1) The magnesium foil was polished with sandpaper, and then a circular magnesium sheet with a diameter of 14 mm was prepared using a punch. The circular magnesium sheet was then cleaned with a hydrochloric acid solution and anhydrous ethanol / dimethyl ether to remove the surface passivation layer and oil film layer, and finally was liquid-sealed into a small transition chamber of a glove box, vacuum-dried, and a magnesium metal magnesium negative electrode was obtained;

[0069] (2) The magnesium metal magnesium negative electrode obtained in step (1) was immersed in a polyaniline / N-methylpyrrolidone solution for 15 min, and then was ultrasonicated for 10 min. The magnesium negative electrode was then taken out, washed, and dried;

[0070] (3) The washed and dried magnesium metal magnesium negative electrode obtained in step (2) was immersed in a silver compound solution for 15 min, and then was ultrasonicated for 10 min. The magnesium negative electrode was then taken out, washed, and dried, and a composite interface film surface modified magnesium negative electrode was obtained.

[0071] The preparation method of the composite interface film surface modified magnesium negative electrode in the comparative examples is the same.

[0072] Performance test:

[0073] The composite interface film surface modified magnesium negative electrode prepared in the above examples and comparative examples was subjected to performance testing, and the specific method was as follows:

[0074] Molybdenum disulfide was used as the positive electrode sheet, the composite interface film surface modified magnesium negative electrode was used as the negative electrode sheet, GF / D glass fiber was used as the separator, 100 μL of 1M Mg(TFSI)2in DME electrolyte was added on the separator, and a 2025 button cell was assembled. A new Wei (BS-9300R type) battery test system was used to test the 2025 button cell prepared at room temperature at a rate of 0.1C, and the working voltage range was 0.01-2.5V. The test results are shown in Table 1.

[0075] As can be seen from Table 1, the composite interface film surface modified magnesium negative electrode provided by the present application exhibits excellent cycle performance when used as the negative electrode of a rechargeable magnesium ion battery.

[0076] In addition, the symmetric battery was used to evaluate the deposition / dissolution efficiency of magnesium ions on magnesium metal. The magnesium negative electrode surface modified by the composite interface film prepared in Example 1 was used as the positive electrode and the negative electrode, GF / D glass fiber was used as the separator, 100 μL of 1M Mg(TFSI)2 in DME electrolyte was added on the separator, and a composite interface film surface modified Mg-Mg symmetric battery was assembled; magnesium metal was used as the positive electrode and the negative electrode of the coin cell, and a Mg-Mg symmetric battery was assembled. The above-mentioned symmetric battery was subjected to constant current charge / discharge test at 25°C by using the new battery test system, and the current density was 1 mA / cm 2 , and the surface capacity was 1 mAh / cm 2 . The constant current charge / discharge test results are shown in Figure 1 .

[0077] The constant current charge / discharge test results can reflect the polarization of the magnesium negative electrode in the constant current charge / discharge process, thereby reflecting the passivation state of the surface of the magnesium negative electrode. Figure 1 FIG. 4 is a constant current polarization curve diagram of the Mg-Mg symmetric battery and the composite interface film surface modified Mg-Mg symmetric battery.

[0078] As can be seen from Figure 1 , in the Mg / Mg symmetric battery composed of fresh Mg, the voltage of the battery fluctuated at the 10th week, and the voltage decreased obviously after 16 weeks of cycle, indicating that a micro-short circuit occurred in the battery. In the composite interface film surface modified Mg-Mg symmetric battery, the battery can still maintain a good overpotential after 400 hours of cycle, indicating that the composite interface film provided by the application has good protection, and can realize the reversible deposition / dissolution of magnesium ions at a current density of 1 mA / cm 2 , and does not cause serious passivation, thereby improving the cycle life and stability of the magnesium metal electrode.

[0079] As can be seen from the performance test results, the composite interface film provided by the application can improve the negative electrode / electrolyte interface properties of the magnesium ion battery, prevent the formation of the passivation film, realize the reversible deposition / dissolution of magnesium ions, and the composite interface film can stably exist in the process of battery charge / discharge cycle, and has a good capacity retention rate. When the magnesium negative electrode surface modified by the composite interface film provided by the application is used as the negative electrode of the rechargeable magnesium ion battery, the rechargeable magnesium ion battery exhibits excellent rate performance and long cycle stability.

[0080] The above describes the preferred embodiments of the application, but the application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the application within the technical concept of the application, and these simple modifications all belong to the protection scope of the application.

[0081] It should be further noted that any technically feasible combination of the various technical features described in the above embodiments is possible, provided that the combination does not contradict itself. In order to avoid unnecessary repetition, the present application does not describe each and every possible combination of the various technical features.

[0082] Furthermore, any combination of the various embodiments of the present application is possible, provided that the combination does not contradict itself, and should be considered as being disclosed by the present application.

Claims

1. A composite interfacial film surface-modified magnesium anode, characterized in that, The magnesium negative electrode is surface-modified with a polyaniline / silver compound composite interface film.

2. The composite interfacial film surface-modified magnesium anode of claim 1, wherein, The silver compound is at least one of silver nitrate, silver sulfate, silver halide, silver acetate, silver propionate, silver aromatic carboxylate, silver alkyl carboxylate, and nano-silver powder.

3. A method for producing the composite interface film surface-modified magnesium negative electrode according to any one of claims 1 to 2, characterized by, The method comprises the following steps: S1. Pretreating the surface of the magnesium negative electrode to remove surface impurities; S2. Immersing the pretreated magnesium negative electrode in a polyaniline solution, performing ultrasonic treatment after immersion, and then taking out, washing, and drying; S3. Immersing the washed and dried magnesium negative electrode in a silver compound solution, performing ultrasonic treatment after immersion, and then taking out, washing, and drying to obtain a magnesium negative electrode surface-modified with a composite interface film.

4. The method for producing a composite interface film surface-modified magnesium negative electrode according to claim 3, characterized by, The mass concentration of the polyaniline solution is 0.1% to 10%, and the mass concentration of the silver compound solution is 0.1% to 10%.

5. A rechargeable magnesium-ion battery, characterized in that, The method comprises a positive electrode material, a magnesium negative electrode surface-modified with a composite interface film according to any one of claims 1 to 2, a separator, and an electrolyte.

6. The rechargeable magnesium-ion battery of claim 5, wherein, The electrolyte comprises an organic solvent, a conductive magnesium salt, and an additive.

7. The rechargeable magnesium-ion battery of claim 6, wherein, The concentration of the conductive magnesium salt in the organic solvent is 0.2 to 2.0 mol / L, and the additive accounts for 0.1% to 10% of the weight of the organic solvent.

8. The rechargeable magnesium-ion battery of claim 6, wherein, The organic solvent is at least one of an organic ether, a nitrile, a carbonate, and an aromatic hydrocarbon compound.

9. The rechargeable magnesium-ion battery of claim 6, wherein, The additive comprises a film-forming additive, and the film-forming additive is at least one of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propanesulfonic acid lactone, butanesulfonic acid lactone, adiponitrile, succinonitrile, LiBOB, and LiODFB.

10. Use of a method for preparing a magnesium negative electrode surface-modified with a composite interface film according to claim 1 or 2 or a magnesium negative electrode surface-modified with a composite interface film according to claim 3 in the preparation of a rechargeable magnesium ion battery.

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