Lithium metal negative plate and preparation method thereof, secondary battery and power utilization device

Abstract

The invention relates to a lithium metal negative plate and a preparation method thereof, a secondary battery and an electric device, the preparation method of the lithium metal negative plate comprises the following steps: mixing AgMF6 with an organic solvent to obtain a mixed solution, M being at least one selected from Ge, Si, Sb, As or Al; the mixed solution is formed on a lithium metal sheet for a reaction, the lithium metal negative plate is obtained, and the lithium metal negative plate comprises the lithium metal sheet and a protective layer formed on the surface of the lithium metal sheet. By adopting the preparation method disclosed by the invention, the stable lithium metal negative electrode plate can be obtained, and the electrochemical performance and the safety performance of a secondary battery can be effectively improved when the lithium metal negative electrode plate is applied to the secondary battery.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a lithium metal negative electrode sheet and a preparation method thereof, a secondary battery and an electrical device. Background Art

[0002] Lithium metal anode sheets are considered to be one of the most promising anode materials for the next generation of high energy density energy storage systems due to their ultra-high theoretical specific capacity. However, when lithium metal sheets are used as anodes in lithium-ion batteries, dendrites are easily generated during the charging and discharging process. The continuous growth of lithium dendrites can cause battery short circuits, which may lead to thermal runaway and potential risks such as fire and explosion.

[0003] In this regard, the prior art discloses the use of antimony trifluoride to modify the lithium metal negative electrode sheet, so that the surface of the lithium metal negative electrode sheet reacts to form a protective layer composed of lithium antimony alloy and lithium fluoride, which can inhibit the generation of lithium dendrites. However, the protective layer has the following defects: (1) The chemical stability of lithium antimony alloy is relatively poor, especially in the electrolyte, and it is easy to react with the electrolyte; (2) When the battery is overcharged or over-discharged, the lithium antimony alloy may undergo incomplete dealloying or uneven deposition, affecting the battery performance; (3) The lithium antimony alloy may decompose or form unstable compounds at high temperatures, resulting in a decrease in battery performance; (4) When the internal temperature of the battery rises, the lithium antimony alloy may undergo chemical reactions, resulting in thermal runaway or rupture of the battery. Summary of the invention

[0004] Based on this, it is necessary to provide a lithium metal negative electrode sheet and its preparation method, a secondary battery and an electrical device to address the above problems. The preparation method can be used to obtain a stable lithium metal negative electrode sheet, which can then be used in a secondary battery to effectively improve the electrochemical performance and safety performance of the secondary battery.

[0005] A method for preparing a lithium metal negative electrode sheet comprises the following steps:

[0006] Mixing AgMF6 with an organic solvent to obtain a mixed solution, wherein M is selected from at least one of Ge, Si, Sb, As or Al;

[0007] The mixed solution is formed on a lithium metal sheet for reaction to obtain a lithium metal negative electrode sheet, wherein the lithium metal negative electrode sheet includes a lithium metal sheet and a protective layer formed on the surface of the lithium metal sheet.

[0008] In one embodiment, M is selected from Sb.

[0009] In one embodiment, the concentration of AgMF6 in the mixed solution is 1 mg / ml-10 mg / ml.

[0010] In one embodiment, in the step of forming the mixed solution on a lithium metal sheet for reaction, the mass ratio of the AgMF6 to the lithium metal sheet is 1:300-1:4000.

[0011] In one embodiment, in the step of forming the mixed solution on the lithium metal sheet for reaction, the temperature is 40° C.-80° C.

[0012] In one embodiment, in the step of mixing AgMF6 with an organic solvent, the temperature is 25°C-40°C.

[0013] A lithium metal negative electrode sheet obtained by adopting the preparation method.

[0014] A secondary battery comprises the lithium metal negative electrode sheet.

[0015] In one embodiment, the secondary battery is a lithium-ion battery.

[0016] An electric device uses the lithium ion battery.

[0017] In the preparation method of the lithium metal negative electrode sheet of the present invention, AgMF6 can react with the lithium metal sheet and generate LiF, single substance Ag and single substance M in situ. First, LiF is an ideal component of the SEI film, and single substance Ag and single substance M can improve the electron transmission efficiency between the lithium metal sheet and the SEI film composed of LiF, optimize the uniformity of lithium deposition and stripping, and inhibit the generation of lithium dendrites. Secondly, single substance Ag and single substance M can also enhance the mechanical strength of the protective layer, thereby improving the electrochemical performance of the secondary battery. Moreover, there is a strong interaction between the Ag element and the M element selected by the present invention, which is a mixed interaction of metal bonds and covalent bonds. Therefore, when single substance Ag and single substance M exist at the same time, the two can also undergo an alloying reaction to form an alloy, and silver can diffuse rapidly in the alloy, which is beneficial to improving the uniformity of the alloy. This alloy has a lower formation enthalpy on the one hand and a smaller volume expansion on the other hand, so it is more stable and not easy to break. Therefore, the preparation method of the present invention can obtain a stable lithium metal negative electrode sheet, which can be effectively improved by being applied to a secondary battery and the electrochemical performance and safety performance of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1are optical photographs of the lithium metal sheet and the lithium metal negative electrode sheet in Example 1, wherein a is an optical photograph of the lithium metal sheet, and b is an optical photograph of the lithium metal negative electrode sheet;

[0020] Figure 2 This is the XRD diagram of the surface protective layer of the lithium metal sheet obtained in Example 1. DETAILED DESCRIPTION

[0021] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0023] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0024] The method for preparing a lithium metal negative electrode sheet provided by the present invention comprises the following steps:

[0025] S1, mixing AgMF6 with an organic solvent to obtain a mixed solution, wherein M is selected from at least one of Ge, Si, Sb, As or Al;

[0026] S2, forming the mixed solution on a lithium metal sheet for reaction to obtain a lithium metal negative electrode sheet, wherein the lithium metal negative electrode sheet includes a lithium metal sheet and a protective layer formed on the surface of the lithium metal sheet.

[0027] In the preparation method of the present invention, the reaction equation of AgMF6 and lithium metal sheet is:

[0028] 6Li+AgMF6→6LiF+Ag+M

[0029] It can be seen from the above reaction equation that when AgMF6 reacts with lithium metal sheet, LiF, elemental Ag and elemental M are generated in situ, and these generated substances together constitute a protective layer.

[0030] First, LiF is an ideal component of the SEI film, and AgMF6 mainly generates LiF when reacting with lithium metal sheets, so the generated LiF can form the SEI film, while elemental Ag and elemental M can improve the electron transfer efficiency between the SEI film composed of lithium metal sheets and LiF, optimize the uniformity of lithium deposition and stripping, and inhibit the formation of lithium dendrites.

[0031] Secondly, the single-element Ag and single-element M can also enhance the mechanical strength of the protective layer, thereby improving the electrochemical performance of the secondary battery.

[0032] Furthermore, there is a strong interaction between the Ag element and the M element selected in the present invention, which is a mixture of metallic bonds and covalent bonds. Therefore, when single substance Ag and single substance M exist at the same time, the two may undergo an alloying reaction to form an alloy, and silver can diffuse rapidly in the alloy, which is beneficial to improving the uniformity of the alloy. On the one hand, this alloy has a lower formation enthalpy, and on the other hand, it has a smaller volume expansion, so it is more stable and not easy to break.

[0033] Therefore, a stable lithium metal negative electrode sheet can be obtained by adopting the preparation method of the present invention, and further applied to a secondary battery to effectively improve the electrochemical performance and safety performance of the secondary battery.

[0034] It can be understood that M in the AgMF6 of the present invention can be selected from one of Ge, Si, Sb, As or Al, or can be selected from two or more of Ge, Si, Sb, As and Al. When selected from two or more, such as Si and Sb, AgMF6 is AgSi m Sb n F6, and m+n=1, preferably, M is selected from Sb, and AgMF6 is AgSbF6.

[0035] In step S1, in the step of mixing AgMF6 with an organic solvent to prepare a mixed solution, the choice of organic solvent is not limited, and commonly used organic solvents such as acetonitrile and N,N-dimethylformamide can be used. During mixing, the temperature is preferably 25°C-40°C, such as 25°C, 30°C, 35°C, 40°C, etc., or a range consisting of any two of these values, which is conducive to the dissolution and dispersion of AgMF6 in the organic solvent. Further, in the prepared mixed solution, the concentration of AgMF6 is preferably 1mg / ml-10mg / ml, such as 1mg / ml, 2mg / ml, 3mg / ml, 4mg / ml, 5mg / ml, 6mg / ml, 7mg / ml, 8mg / ml, 9mg / ml, 10mg / ml, etc., or a range consisting of any two of these values.

[0036] In step S2, in the step of forming the mixed solution on the lithium metal sheet for reaction, the mass ratio of the AgMF6 to the lithium metal sheet is preferably 1:300-1:4000, for example, 1:300, 1:500, 1:800, 1:1000, 1:1500, 1:2000, 1:2500, 1:3000, 1:3500, 1:4000, etc., or a range consisting of any two of these values, such as between 1:800-1:1000, etc., so that the thickness of the protective layer can be controlled.

[0037] Furthermore, in the step of forming the mixed solution on a lithium metal sheet for reaction, the temperature is preferably 40°C-80°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc., or a range consisting of any two of these values, which is not only beneficial to promote the reaction, but also beneficial to the volatilization of the organic solvent.

[0038] Furthermore, the present invention also provides a lithium metal negative electrode sheet obtained by the preparation method. It can be understood that the lithium metal negative electrode sheet includes a lithium metal sheet and a protective layer coated on the surface of the lithium metal sheet, and the protective layer includes LiF, single substance Ag, single substance M, and an alloy formed by Ag and M, so that the lithium metal negative electrode sheet has excellent stability.

[0039] The present invention also provides a secondary battery, comprising the lithium metal negative electrode sheet. Since the lithium metal negative electrode sheet of the present invention has excellent stability, the electrochemical performance and safety performance of the secondary battery can be effectively improved.

[0040] The secondary battery of the present invention may be a lithium ion battery, a sodium ion battery, an all-solid-state battery, etc., preferably a lithium ion battery.

[0041] The present invention also provides an electric device using the lithium-ion battery, which can be electronic devices such as mobile phones and notebook computers, or new energy vehicles.

[0042] Hereinafter, the lithium metal negative electrode sheet and its preparation method, the secondary battery and the electrical device will be further described through the following specific examples.

[0043] Example 1

[0044] First, weigh 100 mg of AgSbF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, while maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0045] Secondly, the mixed solution obtained above was evenly dripped onto the surface of the lithium metal sheet, and the mass ratio of AgSbF6 to the lithium metal sheet was controlled to be 1:300. Then it was placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet.

[0046] Depend on Figure 1 It can be seen that after the lithium metal sheet reacts with AgSbF6, a protective layer is formed on the surface. Figure 2 It can be seen that the protective layer is mainly composed of LiF without lithium antimony alloy.

[0047] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0048] Example 2

[0049] First, weigh 50 mg of AgSbF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, while maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0050] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgSbF6 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, in which the protective layer is composed of single substance Ag, single substance Sb, LiF and silver-antimony alloy.

[0051] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0052] Example 3

[0053] First, weigh 20 mg of AgSbF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, while maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0054] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgSbF6 to the lithium metal sheet is controlled to be 1:2000. Then it is placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, in which the protective layer is composed of single substance Ag, single substance Sb, LiF and silver-antimony alloy.

[0055] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0056] Example 4

[0057] First, weigh 10 mg of AgSbF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0058] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgSbF6 to the lithium metal sheet is controlled to be 1:4000. Then it is placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, in which the protective layer is composed of single substance Ag, single substance Sb, LiF and silver-antimony alloy.

[0059] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0060] Example 5

[0061] First, weigh 50 mg of AgGeF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0062] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgGeF6 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, in which the protective layer is composed of single substance Ag, single substance Ge, LiF and silver-germanium alloy.

[0063] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0064] Example 6

[0065] First, weigh 50 mg of AgSiF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, while maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0066] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgSiF6 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, in which the protective layer is composed of single substance Ag, single substance Si, LiF and silver silicon alloy.

[0067] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0068] Example 7

[0069] First, weigh 50 mg of AgAsF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0070] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgAsF6 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, in which the protective layer is composed of single substance Ag, single substance As, LiF and silver-arsenic alloy.

[0071] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0072] Example 8

[0073] First, weigh 50 mg of AgAlF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, while maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0074] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgAlF6 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, in which the protective layer is composed of single substance Ag, single substance Al, LiF and silver-aluminum alloy.

[0075] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0076] Comparative Example 1

[0077] First, weigh 50 mg of SbF3 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0078] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of SbF3 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C and dried to obtain a lithium metal negative electrode sheet, in which the protective layer is composed of lithium antimony alloy and LiF.

[0079] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0080] Comparative Example 2

[0081] First, 50 mg of LiSbF6 powder was weighed and placed in a glass bottle, 10 ml of acetonitrile solution was added, and the glass bottle was sealed with a sealing film. Then the glass bottle was placed on a magnetic stirrer and stirred for 5 h, and the temperature was maintained at 30°C to obtain a uniform mixed solution.

[0082] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of LiSbF6 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C and dried to obtain a lithium metal negative electrode sheet, the protective layer of which is composed of LiF and single substance Sb.

[0083] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0084] Comparative Example 3

[0085] First, weigh 50 mg of AgSnF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, while maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0086] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgSnF6 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, the protective layer of which is composed of LiF, single substance Sn, and single substance Ag.

[0087] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0088] Comparative Example 4

[0089] First, weigh 50 mg of AgSeF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0090] Secondly, the mixed solution obtained above was evenly dripped on the surface of the lithium metal sheet, and the mass ratio of AgSeF6 to the lithium metal sheet was controlled to be 1:800. Then it was placed on a heating table at 40°C for static drying to obtain a lithium metal negative electrode sheet, the protective layer of which consisted of LiF, elemental Se and elemental Ag.

[0091] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0092] Comparative Example 5

[0093] First, weigh 50 mg of MgSiF6 powder and put it into a glass bottle, add 10 ml of acetonitrile solution, and seal the glass bottle with a sealing film. Then place the glass bottle on a magnetic stirrer and stir for 5 hours, while maintaining the temperature at 30°C to obtain a uniform mixed solution.

[0094] Secondly, the mixed solution obtained above is evenly dripped on the surface of the lithium metal sheet, and the mass ratio of MgSiF6 to the lithium metal sheet is controlled to be 1:800. Then it is placed on a heating table at 40°C and dried to obtain a lithium metal negative electrode sheet, the protective layer of which is composed of LiF, elemental Si and elemental Mg.

[0095] The lithium metal negative electrode sheet obtained above is assembled in the order of positive electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, lithium sheet, gasket, spring sheet, and negative electrode shell, and then pressed to obtain a symmetrical battery.

[0096] The symmetrical battery obtained above was tested for performance at 25°C and 1 mA·cm -2 The results are shown in Table 1.

[0097] Table 1

[0098]

[0099] It can be seen from Table 1 that the lithium metal negative electrode sheet obtained in the embodiment of the present invention has small polarization and good stability, and can be effectively used in secondary batteries to improve the electrochemical performance and safety performance of the secondary batteries.

[0100] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a lithium metal negative electrode sheet, characterized in that: The following steps are involved: Mixing AgMF6 with an organic solvent to obtain a mixed solution, wherein M is selected from at least one of Ge, Si, Sb, As or Al; The mixed solution is formed on a lithium metal sheet for reaction to obtain a lithium metal negative electrode sheet, wherein the lithium metal negative electrode sheet includes a lithium metal sheet and a protective layer formed on the surface of the lithium metal sheet.

2. The method for preparing a lithium metal negative electrode sheet according to claim 1, characterized in that: M is selected from Sb.

3. The method for preparing a lithium metal negative electrode sheet according to claim 1, characterized in that: The concentration of AgMF6 in the mixed solution is 1 mg / ml-10 mg / ml.

4. The method for preparing a lithium metal negative electrode sheet according to claim 1, characterized in that: In the step of forming the mixed solution on a lithium metal sheet for reaction, the mass ratio of the AgMF6 to the lithium metal sheet is 1:300-1:4000.

5. The method for preparing a lithium metal negative electrode sheet according to claim 1, characterized in that: In the step of forming the mixed solution on the lithium metal sheet for reaction, the temperature is 40° C.-80° C.

6. The method for preparing a lithium metal negative electrode sheet according to any one of claims 1 to 5, characterized in that: In the step of mixing AgMF6 with the organic solvent, the temperature is 25°C-40°C.

7. A lithium metal negative electrode sheet obtained by the preparation method according to any one of claims 1 to 6.

8. A secondary battery, characterized in that: Comprising the lithium metal negative electrode sheet as described in claim 7.

9. The secondary battery according to claim 8, characterized in that: The secondary battery is a lithium ion battery.

10. An electrical device, characterized in that: Use of the lithium ion battery as claimed in claim 9.

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