WO2020076188A1

WO2020076188A1 - Aluminum-ion battery

Info

Publication number: WO2020076188A1
Application number: PCT/RU2019/000728
Authority: WO
Inventors: Ludmila Avgustovna ELSHINA; Roman Viktorovich MURADYMOV; Peter Yurievich SHEVELIN; Konstantin Vladelenovich DRUZHININ; Varvara Andreevna ELSHINA
Original assignee: Joint Stock Co "irkutsk Electronetwork Company" Jsc "ienk"
Current assignee: Joint Stock Co "irkutsk Electronetwork Company" Jsc "ienk"
Priority date: 2018-10-11
Filing date: 2019-10-11
Publication date: 2020-04-16
Anticipated expiration: 2021-04-11
Also published as: RU2701680C1

Abstract

The anode the chemical rechargeable power source and chemical rechargeable power source using it are proposed, in which the anode is made of aluminum-graphene composite material containing from 99 to 99.9 wt. % aluminum containing not more than 0.1 wt. % impurities and graphene - the rest. In the particular case of the implementation of the invention, the anode material may contain graphene in the form of scales with a thickness, mainly, in 3 layers of graphene and with transverse dimensions ("length" and "width") from 2 μm to 50 ηm, uniformly distributed throughout the material without forming continuous network of graphene in aluminum. In addition, the anode material can be made by melting aluminum in an alkali metal halide melt containing 0.1-20 wt.% Carbon-containing additive for 1-5 h at 700-750 ° C with further slow cooling at a rate not exceeding 1 deg / min, when using a carbon-containing additive from the series, including carbides of metals or non-metals or solid organic substances, such as hydrocarbons, or carbohydrates, or carboxylic acids.

Description

ALUMINUM-ION BATTERY

The invention relates to chemical power sources and may be used to create chemical power sources with high density of stored energy and short charge time, including the creation of aluminum-graphene batteries and supercapacitors.

Today, the most common type of battery is lithium-ion, but it is not very suitable for energy storage systems, not only because of its high cost, but also of limited cycling, which imposes restrictions on the increase in charge and discharge currents due to the possibility of dangerous inflammation. Aluminum-ion batteries can reduce the requirements for charging and discharge currents due to the fact that the failure of the aluminum-ion battery is not accompanied by catastrophic results.

Patents describing aluminum-ion batteries are known in the art, for example, US9466853, 5/04/2012 patent, Gilbert M. Brown, Mariappan Parans Paranthaman, Sheng Dai, Nancy J. Dudney,“High energy density aluminum battery”, in which the battery contains an anode containing aluminum metal, a cathode containing spinel Al2Mn04, an electrolyte that is an ionic liquid with aluminum-containing ions.

From the patent US9843070B2, 03/09/2015, Hongjie Dai, Meng-Chang, Lin Ming, Gong Bingan, Lu Ying, Peng Wu,“Ultra-fast rechargeable metal-ion battery”, is known a method of producing a fast-rechargeable metal-ion battery, where aluminum is used as an anode, pyrolytic graphite foil is used as a cathode, and ionic liquid 1 -ethyl-3 -methylimidazolium chloride is used as an electrolyte.

From US Patent 9425455 B 1,23/08/2016, JJ Vajo, AF Gross, P. Liu, J. Hicks-Gamer, SV Atta,“Cathode precursors for batteries and methods of making”, is known for an improved aluminum battery consisting of an aluminum anode, a non-aqueous electrolyte, and a cathode containing a metal oxide, metal fluoride, metal sulfide, or sulfur. The battery has a high specific energy specific gravity of the material and good resistance to cycling at different operating temperatures. This solution is closest to the present invention.

An ionic liquid is used as electrolytes in these batteries which is a eutectic mixture of a strong Lewis acid - aluminum halide (AlCl₃) and the main amide ligand (urea or acetamine) of Lewis. As cathode materials - layered materials, which, as in lithium-ion batteries, provide intercalation-deintercalation of aluminum-containing ions into the interlayer space. It can be various types of graphite - from natural to thermally expanded, graphene and its derivatives, as well as perovskite-like oxide materials - oxides of molybdenum, vanadium, manganese, as well as some sulfides, in particular nickel and molybdenum sulfide. High-purity aluminum is currently used as anodes in aluminum-ion batteries.

The disadvantages of the known solutions are determined by the use of anode from chemically pure aluminum. In particular, the aluminum anode is oxidized to oxides and hydroxides even by trace amounts of oxygen and water, which inevitably remain in the ionic liquid after preparation, which shortens the life of the batteries. At all stages from the production of foil to sealing the finished battery is required to limit the contact of the surface of aluminum with water and oxygen. In addition, pure aluminum anodes are more susceptible to degradation in ionic liquids than lithium battery anodes.

The objective of the invention is to increase the aluminum-ionic conductivity in chemical power sources and increase the resistance of the anode to the effects of an aggressive environment at all stages of production and use, including the effects of electrolytes of supercapacitors and aluminum-ion batteries.

The technical result achieved with the use of the invention is reducing production costs, increasing the service life of finished products, as well as in increasing the specific electrical capacitance of finished products and charge and discharge currents. These benefits allow to expand the scope of application of chemical power sources and reduce environmental damage from products that are unsuitable for further use. In addition, the invention improves the electrochemical stability of the anode, increases the storage time of current sources without recharging, increases the number of recharge cycles and, accordingly, the service life of finished products.

To achieve a technical result, an anode of a chemical rechargeable power source is made of an aluminum-graphene composite material containing from 99 to 99.9 wt. % of aluminum containing not more than 0.1 wt. % impurities and graphene - the rest. In the particular case of the implementation of the invention, the anode material may contain graphene in the form of flakes with a thickness, mainly, in 3 layers of graphene and with transverse dimensions ("length" and "width") from 2 pm to 50 pm, uniformly distributed throughout the material without forming continuous network of graphene in aluminum. The anode material can be made according to the technology described in the patent of the Russian Federation No. 2623410 dated 07/20/2015, for example, by melting aluminum in a melt of alkali metal halides containing 0.1-20 wt.% Carbon- containing additive, within 1-5 h. at a temperature of 700-750 °C with further slow cooling at a rate of not more than l°C /min, where the carbon-containing additive is chosen from the series, including metal or non-metal carbides or solid organic substances, such as hydrocarbons, or carbohydrates, or carboxylic acids. In this case, the anode can be made in the form of a foil produced by hot or cold rolling of the anode material. To achieve a technical result, a chemical rechargeable power source contains, in cross section, alternating layers of a cathode, a separator and a flat anode, wherein the anode is made from an aluminum-graphene composite material containing from 99 to 99.9 wt. % aluminum containing, it turn, not more than 0.1 wt. % impurities and graphene - the rest, while the chemical power source contains an electrolyte that fills the free space between the anode and the cathode, and the cathode is made flat and contains a metal base, covered on both sides with layers of carbon, ensuring the mechanical strength of the coating. In the particular case of the implementation, the anode can be performed by rolling a composite material, for example, by repeatedly rolling the anode material, the final stage of which is cold rolling, while at least one rolling stage preceding the final one can be hot rolling.

The separator of a chemical power source can be made porous from a material that is chemically resistant to electrolyte, for example, from polyethylene or tetrafluoroethylene with an open pores diameter from 40 to 160 pm. The separator can be made pre-impregnated with electrolyte before assembling a chemical current source, for example, by keeping in the electrolyte for at least 1 and not more than 5 days or using vacuum impregnation technology.

The anode of the chemical power source may contain graphene in the form of scales or flakes with a thickness, mainly, in 3 layers of graphene and transverse dimensions from 2 pm to 50 pm. The anode material can be made according to the technology described in the patent of the Russian Federation No. 2623410 dated 07/20/2015, including by melting aluminum in a melt of alkali metal halides containing 0.1-20 wt.% carbon-containing additive, within 1-5 h. at a temperature of 700-750 °C with further slow cooling at a rate of not more than l°C /min, while using a carbon-containing additive comprising at least one of the components belonging to metal carbides or non-metal carbides or to solid organic substances, as hard organic substances may be used together or separately hydrocarbons, carbohydrates and carboxylic acids.

As an electrolyte in a chemical power source, a solution of aluminum salts in an organic polar solvent can be used, for example, the electrolyte can be made as a mixture of 1 -methyl-3 - ethylimidazolium chloride, and anhydrous aluminum trichloride in ratios from 1 : 0.4 to 1 : 2 by weight.

As the material of the base of the cathode, metal foil can be used, made, for example, of the metal from the sixth group of the periodic table of elements or iron, or their alloy modified with maximum ductility, where tungsten and molybdenum may be used as elements of the sixth group, and a layer of carbon on the cathode can be formed in form of several layers of graphene, the layers of which can be applied by airbrushing with subsequent annealing of the deposited layers, where 3 to 10 layers of graphene can be applied. Also, graphene layers can be applied by mechanically applying a suspension of graphene in an organic solvent on the substrate material, followed by rolling the solution on the substrate material and annealing. Also a layer of carbon on the cathode can be formed in form of several thin graphite layers, which can be formed by removing 10 pm thick layers from the graphite foil and applying the split layers to the substrate material and then rolling layers together with the substrate.

The cathode of the chemical power source can be kept in the electrolyte before assembling the chemical power source, for example, for at least 1 and not more than 7 days, or the carbon layer of the cathode can be soaked with electrolyte before assembling the chemical power source using vacuum impregnation technology. When analyzing the properties of batteries in which the invention was implemented, it was found that the material used for the manufacture of the anode has improved anti-corrosion properties in comparison with electrodes made of pure aluminum. The mechanism of this property is not completely apprehensible, but can be explained by the "extrusion" of graphene to the surface, in the process of forming aluminum-graphene foil, with the formation of a thin and dense protective film. This circumstance is partially confirmed by the need to“train” aluminum-graphene batteries for 5-10 full charge-discharge cycles in order to achieve performance in terms of capacity and output current. Upon completion of training, aluminum- graphene batteries, as reflected below, show significant advantages compared with batteries made with an anode of pure aluminum. In other rechargeable power sources, products with an anode of an aluminum-graphene composite show an increase in the stability of parameters and an increase in the service life, as compared to products with an aluminum anode.

The tests have shown that batteries with an anode, in which the content of graphene is below 0.1 wt. % do not differ from batteries with anodes of pure aluminum, and the increase in the content of graphene in the anodes is more than 1 wt. % leads to an erosion of the anode during operation. The use of a separator in batteries with a pore size of 40 to 160 pm ensures an optimal combination of the separator strength and the minimum number of voids in the separator not filled with electrolyte.

The use of a graphene layer on the anode with a thickness of 3 to 7 graphene layers is optimal from the view of simplifying the production technology of a mechanically strong graphene layer and ensuring high electrical parameters of the battery, for example, thinning the thickness of the graphene layer does not lead to any positive changes in the battery and increase the thickness may lead to loss of functionality.

The required parameters of graphene distributed in the anode material are achieved by using the proposed method of manufacturing the aluminum-graphene composite. In particular, the content of graphene flakes in the synthesized material, as well as their size, can be regulated by the amount and type of carbon-containing precursor: metal carbides or non-metals, or organic precursors, temperature and synthesis time, as well as cooling and/or further heat treatment parameters in molten salts. The required compositions and parameters for the synthesis of graphene are now determined empirically. However, it should be noted that the average content of graphene in each metal layer after cooling is a constant value that does not vary with depth. As a rule, graphene flakes are formed in a plane parallel to the horizontal surface. In this regard, it is proposed to produce anode foil by rolling the source material in a plane parallel to the plane of formation of most graphene scales.

The lower limit of the temperature range for the production of an aluminum-graphene composite material is 700 °C , and is determined on the basis of the melting point of aluminum 662 °C , and the melting point of the chloride-fluoride electrolyte so that the entire volume of the salt electrolyte, as well as metals and alloys, is melted the course of the experiment. When the temperature rises above 750 °C , a significant salinity is formed during the interaction by the reaction of aluminum trichloride, which affects the environmental friendliness and processability of the process. In addition, an increase in the reaction temperature is undesirable due to the increased risk of formation of aluminum carbide.

Thus, the melting point of aluminum and salt electrolytes determines the optimal temperature range for the synthesis of aluminum-graphene composites.

The time of the process of high-temperature interaction is selected based on the rate of interaction of carbon-containing components of the melt with liquid aluminum in order to forced interaction, allowing to achieve higher concentrations of carbon atoms in liquid aluminum. The time of solidification of molten aluminum is more critical, since in the process of extremely slow solidification of aluminum that carbon atoms in the aluminum matrix are combined into graphene scales. The higher the concentration of carbon atoms achieved during high-temperature interaction of molten aluminum metals with carbon-containing precursors, as well as the temperature of high- temperature synthesis, the more time is required for the formation of graphene layers with gradual cooling. The cooling rate should not exceed l°C /min, since at higher cooling rates, the solidification of a metal droplet occurs more rapidly and as a result of the synthesis inside of aluminum, not all graphene can be formed, but other allotropic modifications of carbon— graphite, diamond, lonsdaleite. Depending on the carbon content and synthesis temperature, cooling may take from 8 to 20 hours.

The carbon-containing additive in the claimed method is a source of atomic carbon, which, when it is supersaturated in aluminum and further cooled, forms graphene scales (flakes) in the metal matrix. As a carbon-containing additive, carbides of metals or non-metals or solid organic substances belonging to the classes of hydrocarbons, or carbohydrates or carboxylic acids are used. These can be saturated hydrocarbons - paraffins or ceresins with the general formula C_l0 and higher, dibasic carboxylic acids - oxalic acid, succinic acid, hydroxy acids - tartaric acid, lactic acid, malic acid, citric acid, quinic acid - products of partial oxidation of sugars, carbohydrates - glucose, fructose, sucrose, maltose, as well as polysaccharides, such as starch and a number of others in the form of powders with a particle size of from 0.5 to 200 microns. The concentration of carbon-containing additives is from 0.1 to 20 wt.%, relative to the weight of the salt sample, and depends on the type of carbon precursor and the synthesis temperature. There were no significant differences in the conditions of the synthesis of graphene using different precursors belonging to the same class of organic or inorganic substances.

The primary processing of the anode billet can be performed by hot rolling, but it is desirable to perform the finishing operations by cold rolling, in which, usually, the sheet temperature does not rise above 70 - 80 °C.

The separator of a chemical power source is made pre-impregnated with electrolyte; it can be made porous from a material that is chemically resistant to electrolyte, for example, from polyethylene or tetrafluoroethylene with an open pores diameter of 40 to 160 pm. The separator may be made pre-impregnated with electrolyte as well. A solution of aluminum salts in an organic polar solvent may be used as an electrolyte in a chemical current source, for example, the electrolyte can be made as a mixture of 1 -methyl-3 -ethylimidazolium chloride, and anhydrous aluminum trichloride in ratios from 1 : 0.4 to 1 : 2 by weight. Studies have also shown that embodiments of anhydrous electrolyte disclosed in US Pat. No. 5,554,458 of September 10, 1996 can also be used as electrolyte. The use of this electrolyte may also characterize the invention, and the cathode may contain iron (II) sulfide as it described in the above mentioned patent.

The possibility of implementing the proposed invention and the technical result achieved is confirmed by the examples below.

Example 1

An electrochemical cell was tested, in which a cold-rolled aluminum-graphene composite material containing 99.5 wt. % aluminum and 0.5 wt. % graphene.

Mixtures of 1 -methyl-3 -ethylimidazolium chloride with anhydrous aluminum trichloride in ratios of 1 : 1.3 (Electrolyte 141) were used as electrolytes. The cathode was made by the method of cold carbon deposition of a rough molybdenum substrate followed by annealing with the formation of a graphene layer 1 mm thick. Table 1 shows a comparison of the results of electrochemical measurements of electrochemical cells with aluminum-composite anodes with different graphene contents with electrochemical cells with an anode of pure aluminum (99.95%) in Electrolytes 141, 142, 143. From Table 1 it can be seen that the current density the exchange of i₀ on the border with the electrolytes under study is aluminum-graphene electrochemical cells 2 times higher, and the charge transfer resistance R is 2 times lower than in an electrochemical cell with pure aluminum as the anode. This indicates a higher electrochemical activity of the aluminum-graphene anode compared with the aluminum anode in the electrochemical cell.

Ta6mma 1.

Example 2

Cycling (repetition of charge/discharge operations) of the electrochemical cell was performed by the galvanostatic method at a current density of 1 mA/cm² of the anode in the voltage range 1.5 - 2.35 V, where the cold-rolled aluminum-graphene composite material was used as the anode containing 99.5 wt. % aluminum and 0.23 wt. % graphene.

The electrolyte used is 1 -methyl-3 -ethylimidazolium chloride mixed with anhydrous aluminum trichloride in a ratio of 1 : 1.3. The cathode was fabricated by the cold threefold deposition of graphene on a molybdenum substrate, followed by annealing. Electrochemical cycling was performed in 100 cycles with an interval of several days. Table 2 shows the results of electrochemical measurements. It is shown that the battery successfully operates for 400 charge/discharge cycles.

In addition, a study was made of the effect of pre-impregnation of the separator with electrolyte on the battery capacity, it was found that prolonged exposure of the separator to the electrolyte before assembly (from 1 to 7 days), as well as pre-treatment of the cathode with electrolyte, ensures that the maximum battery capacity reaches 10 cycles instead of 200 shown in the table below. Table 2

Example 3

An electrochemical cell was cycled, where a cold-rolled foil of an aluminum-graphene composite material containing 99.57 wt.% of aluminum and 0.43 wt. % graphene was used as the anode. The cycling was carried out in a discontinuous mode by the galvanostatic method at a current density of 0.26 mA/cm2. Cycling was performed in the following sequence: the cell was subjected to 100 charge/discharge cycles, then it was stored for 2 weeks, then it was subjected to 100 cycles and left for storage for 1 week, then 100 cycles and one week, after which it was subjected to 700 charge/cycles discharge. In such a discontinuous mode, with a cell charge of up to 2.35 V, the resulting capacitance for a cathode carbon material of 38 mAh/gr was obtained. The drop in the cell capacity did not exceed 7% per 1000 cycles, which proves the electrochemical stability of the cell with an aluminum-composite material during its storage.

Example 4

When cycling the electrochemical cell where as the anode used cold-rolled foil of aluminum- graphene composite material containing 99.57 wt. % aluminum and 0.43 wt. % graphene, was produced in the following mode: 100 cycles at a current density of 0.65 mA/cm2 of the anode, 1000 cycles at a current density of 1 mA/cm2, 1000 cycles at a current density of current density of 1.95 mA/cm2, and 1000 cycles at current density of 3.9 mA/cm2 anode. Porous open-cell polyethylene was used as a separator; 1 -methyl-3 -ethylimidazolium chloride mixed with anhydrous aluminum trichloride in a 1 : 1.3 ratio was used as an electrolyte. The cathode was made by the method of double cold deposition of graphene, followed by annealing on a rough tungsten substrate. This cell worked in the presented mode for 3100 cycles without loss of capacity. Then, the same cell was subjected to 100 charge/discharge cycles in an asymmetrical mode, namely, at a high charge rate and low discharge rate in the voltage range 1.5 - 2.3 V. At a charge rate of 0.85 mA/cm2 of the anode and discharge rate 0.262 mA/cm2 anode. Coulomb efficiency was measured (the percentage of charge removed from the cell during the discharge to the charge that entered the cell during the charge) was 97% in the second cycle and 98% in the hundredth cycle.

At a charge rate of 1.544 mA/cm2 of the anode and a discharge rate of 0.262 mA/cm2 of the anode, the Coulomb efficiency of 98% was measured on the second cycle and 98.5% on the hundredth cycle.

Example 4 confirms the high efficiency of cells with the anode of the proposed design.

Claims

Claims:

1. An anode of a chemical rechargeable power source, made of aluminum-graphene composite material containing from 99 to 99.9 wt. % aluminum containing not more than 0.1 wt. % impurities and graphene - the rest.

2. The anode of claim 1, characterized in that it contains graphene in the form of flakes with thick, mainly in 3 layers of graphene and with transverse dimensions from 2 pm to 50 pm, uniformly distributed throughout the volume of the anode material without forming a continuous network of graphene in aluminum.

3. The anode of claim 1, characterized in that the material of the anode is made by melting aluminum in a melt of alkali metal halides containing 0.1-20 wt.% carbon-containing additive for 1-5 h at a temperature of 700-750 °C with further slow cooling at a rate of not more than 1 °C /min, using a carbon-containing additive from the series, including carbides of metals or non- metals or solid organic substances, such as hydrocarbons, or carbohydrates, or carboxylic acids.

4. The anode of claim 3, characterized in that it is made in the form of foil produced by hot or cold rolling of the anode material.

5. Chemical rechargeable power source containing an anode made of aluminum-graphene composite material containing from 99 to 99.9 wt. % aluminum containing not more than 0.1 wt. % of impurities and graphene - the rest, the cathode and the separator located in the space between the anode and the cathode, and the electrolyte, the electrolyte fills the free space between the anode and the cathode.

6. Chemical power source according to claim 5, characterized in that the cathode is made flat and contains a metal base coated on both sides with carbon layers, ensuring the mechanical strength of the coating, and the chemical power source contains, in cross section, alternating layers of the cathode, the separator and the anode.

7. Chemical power source according to claim 5, in which the anode is made by rolling a composite material.

8. Chemical power source according to claim 7, characterized in that the anode is made by repeated rolling of the anode material, the final stage of which is cold rolling.

9. Chemical power source of claim 8, characterized in that at least one stage of rolling, preceding the final, is hot rolling.

10. Chemical power source according to claim 5, characterized in that the separator is made porous from a material that is chemically resistant to electrolyte and has an open pore diameter of 40 to 160 microns.

11. Chemical power source of claim 5, characterized in that the separator is made of polyethylene or tetrafluoroethylene.

12. Chemical power source of claim 5, characterized in that the separator is made pre- impregnated with electrolyte before assembling the chemical power source.

13. Chemical power source of claim 12, characterized in that the separator is made kept in the electrolyte for at least 1 and not more than 5 days.

14. Chemical power source according to the claim 13, characterized in that the separator is impregnated with electrolyte using vacuum impregnation technology.

15. Chemical power source according to claim 5, characterized in that the anode contains graphene in the form of flakes with a thickness mainly of 3 layers of graphene and transverse dimensions from 2 pm to 50 pm.

16. Chemical power source according to claim 5, characterized in that the anode material is made by melting aluminum in an alkali metal halide melt containing 0.1-20 wt.% of carbon- containing additive for 1-5 hours at a temperature of 700-750 °C with further slow cooling at a rate of not more than 1 °C /min, while using a carbon-containing additive comprising at least one of the components belonging to metal carbides or non-metal carbides or solid organic substances.

17. Chemical power source according to claim 16, characterized in that hydrocarbons, carbohydrates and carboxylic acids are used as solid organic substances.

18. Chemical power source according to claim 5, characterized in that a solution of aluminum salts in an organic polar solvent is used as an electrolyte.

19. Chemical power source of claim 18, characterized in that the electrolyte is made in the form of a mixture of 1 -methyl-3 -ethylimidazolium chloride, and anhydrous aluminum trichloride in ratios from 1 : 0.4 to 1 : 2 by weight.

20. Chemical power source according to claim 5, characterized in that metal foil is used as the material of the base of the cathode.

21. Chemical power source of claim 5, characterized in that the base material used is a foil from the sixth group elements of the periodic table of elements or iron, or their alloy in the modification with maximum ductility.

22. Chemical power source of claim 21, characterized in that tungsten and molybdenum are used as elements of the sixth group.

23. Chemical power source according to claim 5, in which the carbon layer is formed by several layers of graphene.

24. Chemical power source according to the claim 23, characterized in that the graphene layers are applied by airbrushing with subsequent annealing of the deposited layers.

25. Chemical power source according to the claim 24, characterized in that from 3 to 7 graphene layers are applied.

26. Chemical power source according to the claim 23, characterized in that the graphene layers are applied by mechanically applying a suspension of graphene in an organic solvent to the substrate material, followed by rolling the solution on the substrate material and annealing.

27. Chemical current source according to the claim 5, in which the carbon layer is formed by several thin graphite layers are formed by splitting off 10 pm thick layers from graphite foil by applying split layers on the substrate material and then rolling the layers together with the substrate.

28. Chemical power source according to claim 5, characterized in that the cathode is maintained in the electrolyte before assembling the chemical current source.

29. Chemical power source according to claim 6, characterized in that the cathode carbon layer is impregnated with electrolyte before assembling the chemical power source using vacuum impregnation technology.

30. Chemical power source according to claim 6, characterized in that the carbon layer of the cathode is impregnated with electrolyte before assembling the chemical power source by holding the cathode in the electrolyte for at least 1 and not more than 7 days.