Preparation method and application of a functional sodium or potassium metal electrode based on an inorganic rare earth compound

Abstract

This application relates to the technical field of energy storage batteries, and particularly to a preparation method and application of a functional sodium or potassium metal electrode based on an inorganic rare earth compound; the functional sodium or potassium metal electrode is an electrode formed by sodium or potassium metal composite with an inorganic rare earth compound; wherein, the mass ratio of the functional sodium or potassium metal to the inorganic rare earth compound is 10-80:90-20; the inorganic rare earth compound is a rare earth metal fluoride; by defining the inorganic rare earth compound as a rare earth metal fluoride and defining the composition raw materials of the functional sodium or potassium metal electrode, sodium fluoride or potassium fluoride and a rare earth alloy can be generated by the reaction of the functional sodium or potassium metal with the rare earth metal fluoride, which can synergistically solve the dendrite growth, volume expansion and unstable interface of the sodium or potassium metal electrode.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage batteries, and particularly to a preparation method and application of a functional sodium or potassium metal electrode based on an inorganic rare earth compound. Background Art

[0002] Lithium-ion batteries have been widely used in the fields of mobile electronic devices, electric vehicles, smart grids, aerospace, etc. due to their advantages such as high energy density, high output power, no memory effect, and environmental friendliness. However, limited by the low theoretical specific capacity of the graphite negative electrode, it can no longer meet the energy density requirements of current various devices. Therefore, it is urgent to develop negative electrode materials with higher theoretical specific capacity.

[0003] The ultra-high theoretical specific capacity and low redox potential of sodium or potassium metal electrodes are considered to be ideal negative electrode materials for constructing next-generation high-energy batteries. However, so far, secondary batteries with sodium or potassium metal as the negative electrode have not been commercially applied yet, which is due to three main problems faced by sodium or potassium metal negative electrodes: (1) uneven current density distribution during the deposition-dissolution process of metal ions, resulting in uneven deposition, forming dendrites, causing safety hazards and irreversible capacity loss caused by "dead sodium or potassium"; (2) different from the insertion and extraction working mechanism of the graphite negative electrode, the host-free property of sodium or potassium metal leads to huge volume changes during cycling, which will cause damage to the structure of the electrode and electrode pulverization; (3) the unstable solid electrolyte interface will exacerbate the parasitic reaction between highly active sodium or potassium metal and the electrolyte, continuously consuming during cycling, reducing the Coulomb efficiency and cycle life of the battery.

[0004] To solve the above problems, researchers have proposed various improvement strategies, but they cannot coordinately control the problems of dendrite growth, volume expansion, and unstable interface. Therefore, it is crucial to develop a technology that can coordinately solve the dendrite growth, volume expansion, and unstable interface of sodium or potassium metal electrodes. Summary of the Invention

[0005] The present application provides a preparation method and application of a functional sodium or potassium metal electrode based on an inorganic rare earth compound to solve the problem that it is difficult to coordinately solve the dendrite growth, volume expansion, and unstable interface of sodium or potassium metal electrodes in the prior art.

[0006] In the first aspect, the present application provides a functional sodium or potassium metal electrode based on an inorganic rare earth compound, and the functional sodium or potassium metal electrode is an electrode formed by sodium or potassium metal compounded with an inorganic rare earth compound;

[0007] Wherein, the mass ratio of the functional sodium or potassium metal to the inorganic rare earth compound is 10-80:90-20;

[0008] The inorganic rare earth compound is a rare earth metal fluoride.

[0009] Optionally, the inorganic rare earth compound further includes a rare earth metal oxide and / or a rare earth metal sulfide.

[0010] Optionally, the rare earth metal includes at least one of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

[0011] Optionally, the thickness of the sodium or potassium metal electrode is 5 μm to 500 μm.

[0012] In a second aspect, the present application provides a method for preparing the functional sodium or potassium metal electrode described in the first aspect, the method comprising:

[0013] Mix the functional sodium or potassium metal and the inorganic rare earth compound, then heat in a dry inert atmosphere and stir until the reaction between the inorganic rare earth compound and the molten sodium or potassium metal is complete to obtain a mixed solution;

[0014] Pour the mixed solution onto the surface of the copper current collector, scrape and coat, and then cool to obtain a sodium or potassium metal electrode composite with an inorganic rare earth compound.

[0015] Optionally, the heating temperature is 100°C to 250°C.

[0016] Optionally, the stirring time is 5 min to 30 min.

[0017] Optionally, the dry inert atmosphere is an argon atmosphere.

[0018] Optionally, the water content of the dry inert atmosphere < 0.1 ppm, and the oxygen content of the dry inert atmosphere < 0.1 ppm.

[0019] In a third aspect, the present application provides an application of the functional sodium or potassium metal electrode described in the first aspect in preparing a battery negative electrode material.

[0020] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0021] A functional sodium or potassium metal electrode based on an inorganic rare earth compound provided by an embodiment of the present application stabilizes a sodium or potassium metal electrode by defining the inorganic rare earth compound as a rare earth metal fluoride and defining the constituent materials of the functional sodium or potassium metal electrode, and using sodium fluoride or potassium fluoride and a rare earth alloy generated by the reaction of the functional sodium or potassium metal with the rare earth metal fluoride. Among them, sodium fluoride or potassium fluoride and the rare earth alloy can serve as an electrode skeleton to release the stress generated during charge and discharge and relieve volume expansion; at the same time, sodium fluoride or potassium fluoride can also strengthen the solid electrolyte interface, physically block the direct contact between sodium / potassium metal and the electrolyte, and inhibit interfacial parasitic reactions; in addition, a stable electrode interface (homogenizing ion flow) and a rare earth alloy (serving as a nucleation site) can induce uniform deposition of the metal and inhibit dendrite growth; therefore, this functional sodium or potassium metal electrode can synergistically solve the problems of dendrite growth, volume expansion, and unstable interface faced by sodium or potassium metal electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments in line with the present application, and are used together with the specification to explain the principles of the present application.

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 Schematic diagram of the structure of a functional sodium or potassium metal electrode composite with an inorganic rare earth compound provided by an embodiment of the present application;

[0025] Figure 2 Schematic diagram of the process flow of the preparation method provided by an embodiment of the present application;

[0026] Figure 3 Comparison chart of the cycling curves of a symmetric battery assembled with the electrode material prepared from sodium metal and YF3 with a mass ratio of 40:60 and untreated blank sodium metal as the electrode provided by an embodiment of the present application;

[0027] Figure 4 Comparison chart of the cycling curves of a symmetric battery assembled with the electrode material formed from potassium metal and CeO2 with a mass ratio of 40:60 and untreated blank sodium metal as the electrode provided by an embodiment of the present application;

[0028] Figure 5 Comparison chart of the cycling curves of a symmetric battery assembled with the electrode material formed from potassium metal and Nd2S3 with a mass ratio of 25:75 and untreated blank potassium metal as the electrode provided by an embodiment of the present application;

[0029] Figure 6 This is a comparison chart of the cyclic curves of a symmetric battery assembled with the electrode material prepared from metallic sodium and YF3 with a mass ratio of 95:5 provided in the embodiments of the present application and untreated blank metallic sodium as the electrode. Detailed implementation manners

[0030] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0031] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments and equipment used in the present application can be obtained through market purchase or can be prepared by existing methods.

[0032] The creative thinking of the present application is as follows:

[0033] Currently, there are various improvement strategies for the three problems faced by sodium or potassium metal anodes, including:

[0034] (1) Introducing electrolyte additives, and using the additives to decompose on the surface of the sodium or potassium metal electrode to form a stable solid electrolyte interface to improve its electrochemical performance. However, it will lose its effect after the additives are consumed.

[0035] (2) Constructing an interfacial protection layer, that is, constructing a high shear modulus barrier layer on the surface of the lithium electrode by in-situ or ex-situ methods to inhibit the growth of dendrites and interfacial parasitic reactions; for example, treating the surface of metallic lithium with a CeF3 solution to form an interfacial protection layer of lithium cerium alloy and lithium fluoride on its surface, so as to achieve the inhibition of lithium dendrite growth and interfacial parasitic reactions. However, this strategy can only play a role in part of the surface and cannot accommodate the volume change during the cycling of the lithium anode.

[0036] (3) Designing a three-dimensional current collector to inhibit the formation and growth of dendrites by reducing the local current density, and at the same time using its skeleton to relieve the volume expansion effect. However, the internal is an open pore structure, which will also lead to more electrolyte exposure and exacerbate the consumption of active sodium or potassium metal and the electrolyte.

[0037] To solve the above problems of dendrite growth, volume expansion and unstable interface, the present application provides the following solutions:

[0038] Such as Figure 1As shown, a functional sodium or potassium metal electrode based on an inorganic rare earth compound, where the functional sodium or potassium metal electrode is an electrode formed by sodium or potassium metal composite with an inorganic rare earth compound;

[0039] Among them, the mass ratio of the functional sodium or potassium metal to the inorganic rare earth compound is 10 - 80:90 - 20;

[0040] The inorganic rare earth compound is a rare earth metal fluoride.

[0041] In the embodiments of the present application, the positive effect of limiting the mass ratio of the functional sodium or potassium metal to the inorganic rare earth compound to 10 - 80:90 - 20 is that within this mass ratio range, it can promote the full reaction of the functional sodium or potassium metal and the inorganic rare earth compound, thereby obtaining sodium fluoride or potassium fluoride and rare earth alloy products, and then synergistically solving the dendrite growth, volume expansion, and unstable interface of the sodium or potassium metal electrode through the generated sodium fluoride or potassium fluoride and rare earth alloy products.

[0042] The positive effect of limiting the inorganic rare earth compound to a rare earth metal fluoride is that since the rare earth metal fluoride can react with the functional sodium or potassium metal to form sodium fluoride or potassium fluoride and rare earth metal alloy, it can synergistically solve the dendrite growth, volume expansion, and unstable interface of the sodium or potassium metal electrode.

[0043] In some alternative embodiments, the inorganic rare earth compound further includes rare earth metal oxides and / or rare earth metal sulfides.

[0044] In the embodiments of the present application, limiting the inorganic rare earth compound to specifically include rare earth metal oxides and rare earth metal sulfides can ensure that in addition to inorganic metal fluorides, other common inorganic rare earth compounds are covered, thereby expanding the source of inorganic rare earth compounds and further increasing the application range of the functional sodium or potassium metal electrode.

[0045] In some alternative embodiments, the rare earth metal includes at least one of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

[0046] In the embodiments of the present application, limiting the specific types of rare earth metals can cover most rare earth metal elements, thereby improving the usability of the functional sodium or potassium metal electrode of the present application.

[0047] In some alternative embodiments, the thickness of the functional sodium or potassium metal electrode is 5 μm - 500 μm.

[0048] In the embodiments of the present application, the positive effect of limiting the thickness of the functional sodium or potassium metal electrode to 5 μm to 500 μm is that within this thickness range, it can cover the thicknesses of most existing functional sodium or potassium metal electrodes, and ensure that a sufficient thickness of rare earth compounds is compounded onto the electrodes formed by sodium or potassium metals.

[0049] As Figure 2 shown, based on a general inventive concept, the present application provides a method for preparing the functional sodium or potassium metal electrode, and the method includes:

[0050] S1. Mix the functional sodium or potassium metal and the inorganic rare earth compound, then heat in a dry inert atmosphere and stir until the reaction between the inorganic rare earth compound and the molten sodium or potassium metal is complete to obtain a mixed solution;

[0051] S2. Pour the mixed solution onto the surface of a copper current collector, scrape and coat, and then cool to obtain a sodium or potassium metal electrode compounded with an inorganic rare earth compound.

[0052] In the embodiments of the present application, in order to make the functional sodium or potassium metal and the inorganic rare earth react sufficiently, by first heating the two to melt one of them (since the melting point of the functional sodium or potassium metal is lower than that of the inorganic rare earth compound, it will melt first), and then stirring to make the two react completely to obtain sodium fluoride or potassium fluoride and a rare earth alloy product, so that the obtained electrode can synergistically solve the dendrite growth, volume expansion and unstable interface of the sodium or potassium metal electrode.

[0053] To ensure the smooth progress of the reaction process, generally, the reactor for mixing the functional sodium or potassium metal and the inorganic rare earth compound uses a stainless steel crucible, because the functional sodium or potassium metal will react with ceramic crucibles and other Si-containing crucibles, resulting in damage to the crucible and doping impurities in the functional sodium or potassium metal at the same time.

[0054] This method is for the preparation method of the above-mentioned functional sodium or potassium metal electrode. The specific composition and structure of the functional sodium or potassium metal electrode can refer to the above embodiments. Since this method adopts some or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated one by one here.

[0055] In some alternative embodiments, the heating is 100 °C to 250 °C.

[0056] In the embodiments of the present application, the positive effect of limiting the heating temperature to 100°C to 250°C is that within this temperature range, it can ensure the melting of functional sodium or potassium metal. Since the melting point of inorganic rare earth compounds is relatively high, generally above 2000°C, it is difficult to melt. At this time, the molten functional sodium or potassium metal can be fully mixed with the inorganic rare earth metal compounds. Even if the formed rare earth alloy melts at this temperature, it will only make the rare earth alloy more evenly distributed in the matrix, thereby better improving the ability of the electrode material to synergistically solve the problems of dendrite growth, volume expansion, and unstable interface of sodium or potassium metal electrodes.

[0057] In some alternative embodiments, the stirring time is 5 min to 30 min.

[0058] In the embodiments of the present application, the positive effect of limiting the stirring time to 5 min to 30 min is that within this time range, the molten functional sodium or potassium metal can react completely with the inorganic rare earth compounds by stirring, thereby ensuring that the amounts of the formed rare earth alloy and sodium fluoride or potassium fluoride are sufficient.

[0059] In some alternative embodiments, the inert atmosphere for drying includes an argon atmosphere.

[0060] In the embodiments of the present application, limiting the inert atmosphere for drying to an argon atmosphere not only makes argon a conventional inert gas and easy to prepare, but also ensures the safe progress of the melting reaction under argon conditions.

[0061] Furthermore, the water content of the inert atmosphere for drying < 0.1 ppm, and the oxygen content of the inert atmosphere for drying < 0.1 ppm.

[0062] Limiting the water content and oxygen content of the inert atmosphere for drying can prevent the functional sodium or potassium metal from reacting with water and oxygen during the melting stage, which will not only cause loss of raw materials but also affect the doping of impurities in the formed electrode material. Moreover, the reaction of the functional sodium or potassium metal with water and oxygen is relatively violent and may cause safety accidents. Therefore, it is necessary to control the water and oxygen in the atmosphere within a lower range.

[0063] Based on a general inventive concept, the present application provides an application of the functional sodium or potassium metal electrode in the preparation of a battery negative electrode material.

[0064] This application is implemented based on the above-mentioned functional sodium or potassium metal electrode. The specific composition and structure of the functional sodium or potassium metal electrode can refer to the above embodiments. Since this application adopts some or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated one by one here.

[0065] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0066] Example 1

[0067] A method for preparing the functional sodium or potassium metal electrode, comprising the following steps:

[0068] (1) Weigh metallic sodium and YF3 in a mass ratio of 40:60 and place them in a stainless steel crucible for later use;

[0069] (2) In an argon-filled glove box (water and oxygen contents are both less than 0.1 ppm), heat a stainless steel crucible to 150°C to melt the sodium metal, and stir continuously to promote a full reaction between the sodium metal and YF3;

[0070] (3) Pour the mixed solution after the above reaction onto the surface of the copper current collector and scrape it with a 20 μm scraper. After cooling, a YF3 composite metal sodium electrode is obtained.

[0071] Example 2

[0072] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is:

[0073] Use metallic potassium and LaF3 with a mass ratio of 30:70; heat the stainless steel crucible to 120°C; and use a 50μm scraper to apply.

[0074] Example 3

[0075] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is:

[0076] The mass ratio of potassium metal and CeO2 is 40:60; heat the stainless steel crucible to 150℃; and apply with a 10μm scraper.

[0077] Example 4

[0078] Comparing Example 4 with Example 1, the difference between Example 4 and Example 1 is:

[0079] The mass ratio of metallic potassium and Sc2O3 is 30:70; the stainless steel crucible is heated to 120°C; and a 100μm scraper is used for scraping.

[0080] Example 5

[0081] Compare Example 5 with Example 1. The differences between Example 5 and Example 1 are as follows:

[0082] Sodium metal and La2S3 with a mass ratio of 50:50; heat the stainless-steel crucible to 100 °C; scrape and coat with a 100-μm scraper.

[0083] Example 6

[0084] Compare Example 6 with Example 1. The differences between Example 6 and Example 1 are as follows:

[0085] Potassium metal and Nd2S3 with a mass ratio of 25:75; heat the stainless-steel crucible to 180 °C; scrape and coat with a 200-μm scraper.

[0086] Comparative Example 1

[0087] Compare Comparative Example 1 with Example 1. The differences between Comparative Example 1 and Example 1 are as follows:

[0088] Sodium metal and YF3 with a mass ratio of 95:5; heat the stainless-steel crucible to 180 °C; scrape and coat with a 50-μm scraper.

[0089] Comparative Example 2

[0090] Compare Comparative Example 2 with Example 1. The differences between Comparative Example 2 and Example 1 are as follows:

[0091] Sodium metal and YF3 with a mass ratio of 5:95; heat the stainless-steel crucible to 120 °C; scrape and coat with a 50-μm scraper.

[0092] Related experiments and performance data:

[0093] Since in Comparative Example 2, sodium metal and YF3 with a mass ratio of 5:95 have a relatively high melting point of the inorganic rare-earth compound during the actual preparation stage, it is difficult to heat and form a molten liquid, and thus it is impossible to obtain the electrode material by scraping and coating. Therefore, taking the button-type symmetric batteries assembled with the electrode materials obtained in Example 1, Example 3, and Example 6 and Comparative Example 1 as examples, the chemical performance of the button-type symmetric batteries obtained from each electrode material was tested. Among them, the preparation method of the metal electrode for the blank control (without adding inorganic rare-earth compounds) is similar to the above steps, and the assembly is completed in a glove box filled with argon (both the water and oxygen contents are less than 0.1 ppm), and a 2032 battery case is used.

[0094] Experimental conditions: When the raw material of the electrode is potassium metal, the electrolyte of the coin-type symmetric battery is 1.0 M KPF6 + EC / DEC / EMC (volume ratio v:v:v = 1:1:1); when the raw material of the electrode is sodium metal, the electrolyte of the coin-type symmetric battery is 1.0 M NaPF6 + EC / DEC / EMC (volume ratio v:v:v = 1:1:1), and the addition amount of the electrolyte is 80 μL for both cases.

[0095] Test methods for related experiments: At a current density of 1 mA / cm 2 , deposition capacity of 1 mAh / cm 2 , the measurement is carried out.

[0096] The results are as Figures 3 to 5 shown. The cyclic stability of the sodium or potassium metal electrode composite with inorganic rare earth compounds has been greatly improved, which is more than twice that of the blank electrode. The improvement of the electrochemical performance of the coin-type symmetric battery is attributed to the fact that this strategy synergistically solves the problems of dendrite growth, volume expansion, and unstable solid electrolyte interface faced by the sodium or potassium metal electrode.

[0097] It can be seen from Figure 6 that compared with the unmodified sodium metal electrode, the electrochemical performance of the sodium metal electrode composite with YF3 has not been significantly improved, mainly because the content of YF3 is too small to play an effective role.

[0098] One or more technical solutions in the embodiments of the present application at least further have the following technical effects or advantages:

[0099] (1) A functional sodium or potassium metal electrode based on inorganic rare earth compounds provided by the embodiments of the present application can not only synergistically solve the problems of dendrite growth, volume expansion, and unstable interface of the sodium or potassium metal electrode, but also form an electron-ion transport channel through the rare earth alloy and sodium fluoride or potassium in the electrode, enabling the electrode reaction to expand from the surface to the bulk phase, which helps to solve the problems of electrode pulverization and "dead sodium or potassium".

[0100] (2) A functional sodium or potassium metal electrode based on inorganic rare earth compounds provided by the embodiments of the present application, the rare earth alloy contained therein can refine the grains during the solidification of the metal electrode, form a dense metal matrix, and can serve as a nucleation site during electrodeposition to induce uniform nucleation of the metal.

[0101] (3) A preparation method of a functional sodium or potassium metal electrode based on inorganic rare earth compounds provided by the embodiments of the present application, this method is simple, efficient, and easy to prepare on a large scale.

[0102] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and the individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within that range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fractional or integer) within the indicated range.

[0103] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" specifically refer to the drawing directions in the drawings. Additionally, in the description of the specification of the present application, the terms "include", "comprise", etc. mean "including but not limited to". In this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this text, "and / or" describes the associated relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B may be singular or plural. In this text, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single items (pieces) or plural items (pieces). For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0104] The above are only the specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a functional sodium or potassium metal electrode based on an inorganic rare earth compound, characterized in that, The functional sodium or potassium metal electrode is an electrode formed by sodium or potassium metal compounded with an inorganic rare earth compound; Mix sodium or potassium metal and an inorganic rare earth compound, then heat in a dry inert atmosphere and stir until the reaction between the inorganic rare earth compound and the molten sodium or potassium metal is complete to obtain a mixture; wherein, the heating temperature is 100°C to 250°C; Pour the mixture onto the surface of a copper current collector, scrape and coat, and then cool to obtain an inorganic rare earth compound-compounded sodium or potassium metal electrode; The mass ratio of the sodium or potassium metal to the inorganic rare earth compound is 10 to 80:90 to 20; the inorganic rare earth compound includes: yttrium fluoride and / or lanthanum fluoride, and the inorganic rare earth compound further includes: at least one of cerium oxide, scandium oxide, lanthanum sulfide, and neodymium sulfide.

2. The method according to claim 1, wherein The stirring time is 5 min to 30 min.

3. The method according to claim 2, wherein The dry inert atmosphere is an argon atmosphere.

4. The method according to claim 3, characterized in that The water content in the dry inert atmosphere is <0.1 ppm, and the oxygen content in the dry inert atmosphere is <0.1 ppm.

5. A functional sodium or potassium metal electrode based on an inorganic rare earth compound, characterized in that, The functional sodium or potassium metal electrode is prepared by the preparation method described in any one of claims 1 to 4.

6. The functional sodium or potassium metal electrode according to claim 5, wherein The thickness of the sodium or potassium metal electrode is 5 μm to 500 μm.

7. Use of a functional sodium or potassium metal electrode as described in claim 5 or 6 in the preparation of a battery negative electrode material.

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