A surface-functionalized metal cluster and its applications

Abstract

The present invention discloses a surface-functionalized metal cluster and its application, relating to the field of battery materials. The metal cluster comprises a metal core and a surface-functionalized layer, wherein the metal core is selected from one or more of copper (Cu), silver (Ag), and gold (Au), and the surface-functionalized layer contains fluorine element (F) and iodine element (I). When the metal cluster is applied to the surface of an all-solid-state lithium metal anode, it can effectively inhibit the growth of lithium dendrites, relieve volume expansion, and improve interfacial stability, thereby improving the performance of the all-solid-state lithium metal battery.

Description

Technical Field

[0001] The present invention relates to the field of battery materials, specifically to a surface-functionalized metal cluster and its application in an all-solid-state lithium metal anode, specifically the application in an all-solid-state lithium metal anode, and particularly to a metal cluster containing fluorine and iodine elements for improving the performance of an all-solid-state lithium metal battery. Background Art

[0002] All-solid-state lithium metal batteries have attracted much attention due to their high energy density and safety. However, problems such as lithium dendrite growth, volume expansion, and side reactions with electrolytes exist during the charge and discharge processes of lithium metal anodes, seriously affecting the cycle life and safety of the batteries. Therefore, how to suppress lithium dendrite growth, relieve volume expansion, and reduce side reactions is the key to the research of all-solid-state lithium metal batteries.

[0003] In response to the above problems, researchers have proposed various solutions, mainly including:

[0004] Electrode structure design: By designing a three-dimensional porous structure or introducing other conductive framework materials to guide the uniform deposition of lithium ions and relieve volume expansion.

[0005] Interface modification: By constructing an artificial protective layer on the surface of the lithium metal anode to inhibit side reactions and improve interface stability.

[0006] Special challenges of all-solid-state lithium metal batteries:

[0007] Compared with traditional liquid lithium-ion batteries, all-solid-state lithium metal batteries use solid electrolytes instead of traditional liquid electrolytes, having higher safety and energy density potential. However, all-solid-state lithium metal batteries also face some unique challenges:

[0008] Poor interface contact: Poor interface contact between the solid electrolyte and the lithium metal anode results in too high interface impedance, affecting the performance of the battery.

[0009] Poor interface chemical stability: Some solid electrolytes have poor chemical stability with lithium metal and are prone to side reactions, leading to deterioration of interface performance.

[0010] Low transport rate of lithium ions in solid electrolytes: Compared with liquid electrolytes, the transport rate of lithium ions in solid electrolytes is lower, limiting the rate performance of the battery.

[0011] Therefore, for all-solid-state lithium metal batteries, it is particularly necessary to develop effective interface modification strategies to improve the interface contact and chemical stability between the solid electrolyte and the lithium metal anode and to enhance the transport efficiency of lithium ions.

[0012] In view of the above problems existing in the background art, the present invention proposes a novel interface modification strategy, that is, using surface-functionalized metal clusters (containing fluorine and iodine elements) to modify the surface of the lithium metal anode. This strategy aims to combine the advantages of fluorine and iodine elements, as well as the good conductivity of metal clusters, and work synergistically to achieve the following purposes:

[0013] Utilize the reaction between fluorine and lithium to generate LiF, form a stable SEI film, improve the interface stability, and reduce side reactions.

[0014] Utilize the relatively large ionic radius of iodine to play a steric hindrance role during lithium deposition, slow down the migration speed of lithium ions, and thus inhibit the rapid growth of dendrites.

[0015] Utilize the good conductivity of metal clusters to improve the interface conductivity and promote the transport of lithium ions.

[0016] Through the above strategy, the present invention aims to solve the interface problems faced by the lithium metal anode in all-solid-state lithium metal batteries, and improve the cycle life, rate performance, and safety of the batteries. Summary of the Invention

[0017] In view of this, the purpose of the present invention is to provide a surface-functionalized metal cluster and its application. This functional layer can effectively inhibit the growth of lithium dendrites, improve the interface contact, enhance the cycle performance and Coulomb efficiency of the lithium metal anode, and is particularly suitable for all-solid-state lithium metal battery systems. The present invention effectively improves the interface contact between the lithium metal and the solid electrolyte by constructing a surface-functionalized metal cluster layer containing fluorine and iodine elements on the lithium foil surface, and has potential advantages in large-scale production.

[0018] The surface-functionalized metal clusters are deposited on the lithium metal. On the one hand, by guiding the uniform deposition of lithium ions. On the other hand, by providing a buffer space or enhancing the mechanical strength of the electrode. On the other hand, by forming a stable interface protection layer. This method provides an effective solution to the key problems in the development of all-solid-state batteries. The application of the surface-functionalized metal clusters of the present invention in all-solid-state lithium metal batteries can still maintain more than 90% of the capacity after 500 cycles, and the cycle life is increased by about 800%.

[0019] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0020] <The first aspect>

[0021] A surface-functionalized metal cluster for a lithium metal anode, the surface-functionalized metal cluster is coated or deposited on the surface of the lithium metal anode, and is prepared by a method including the following steps:

[0022] The surface of the metal core is surface-treated to form a surface-functionalized layer, thereby obtaining a surface-functionalized metal cluster;

[0023] The surface treatment is fluorination and / or iodination treatment, and the composition of the surface-functionalized layer is the corresponding metal fluoride and / or metal iodide.

[0024] Preferably, the metal core is a metal nanocluster having a cubane-type structure, with an average particle size of 1-100 nm. The metal of the metal core includes one or more of Cu, Ag, and Au, preferably Cu and / or Ag.

[0025] Preferably, the metal fluoride and / or metal iodide in the surface-functionalized layer has a cubane-type structure. The cubane-type structure is represented as M4X4 ( Figure 4 ), M is one of Cu, Ag, and Au, and X is one of F and I; preferably Cu4F4, Ag4I4, Cu4I4, and Ag4F4. The metal nanocluster is [Cu4F4] n or [Ag4I4] n , and the cubane-type structure forms a metal nanocluster.

[0026] Preferably, the preparation method of the metal core includes one of chemical reduction method, solvothermal method, microemulsion method, and vapor deposition method. The preparation steps of the metal core are: under the protection of an inert gas environment, metal nanoclusters are prepared by chemical reduction method, solvothermal method, microemulsion method or vapor deposition method.

[0027] Preferably, the preparation method of copper nanoclusters: Slowly drop the NaBH4 solution into the CuCl2 solution, and copper nanoclusters are obtained after stirring and reacting. The molar ratio of NaBH4 to CuCl2 is 1.2-1.8:3. The stirring reaction time is 30-40 min. The content in the NaBH4 solution is 0.01-0.025 mol / 50 ml; the content in the CuCl2 solution is 0.02-0.04 mol / 20 ml.

[0028] Preferably, the preparation method of silver nanoclusters: Mix the AgNO3 solution and the PVP solution to obtain a mixed solution; then add the KI solution to the mixed solution, and silver nanoclusters are obtained after stirring and reacting. The mass ratio of KI, AgNO3, and PVP is 0.15-0.2:0.15-0.2:0.1. The stirring reaction time is 30-40 min. The content of the KI solution is 0.15-0.2 g:50 ml; the content of the AgNO3 solution is 0.15-0.2 g:50 ml; the content of the PVP solution is 0.4-0.6 wt%.

[0029] Preferably, the microemulsion method includes:

[0030] (1) Prepare aqueous solutions of metal salts and halide salts respectively;

[0031] (2) Dissolve the surfactant in the oil-phase solvent, and add the aqueous solutions of metal salts and halide salts respectively to form an inverse microemulsion;

[0032] (3) Mix the two inverse microemulsions and react under stirring;

[0033] (4) Wash and dry the product.

[0034] Preferably, the average particle size is 1 - 10 nm.

[0035] Preferably, the surface treatment steps: Prepare a salt solution of fluoride salt and / or iodide salt, drop it into the metal core dispersion, stir and react to obtain the surface-functionalized metal cluster.

[0036] The mass ratio of the metal core to the fluoride salt and / or iodide salt is 1:1 - 3.

[0037] The fluoride salts include one or more of LiF, NaF, and AgF; the iodide salts include one or more of LiI, NaI, and KI. For other halides, such as metal chlorides, the functional layer is inferior to metal fluorides and iodides in terms of stability, corrosion resistance, surface energy, specific electronic properties, etc., and cannot meet the application requirements. Moreover, the chlorination reaction is more difficult to precisely control, prone to overreaction or generation of by-products, affecting the quality and performance of the surface functional layer.

[0038] The solubility of the salt solution is 0.01 - 0.1 g / ml; the content of the metal core in the metal core dispersion is 0.01 - 0.05 g / ml. The stirring reaction time is 20 - 30 h.

[0039] The surface of the obtained surface-functionalized metal cluster is a fluorine and / or iodide of the cubane-type structure, and the inside is a metal cluster. The surface treatment reaction tends to occur on the surface of the metal core to form a surface-functionalized layer of metal-halogen (such as Cu-F, Ag-I), while the inside remains in the metallic state. This is because: the oxidation reaction of halogen ions (F - or I - ) with metals (such as Cu, Ag) preferentially occurs on the surface of the metal core with high surface energy to form a stable halide passivation layer, preventing further internal reactions. And fluorine and / or iodine elements are located on the surface of the metal cluster. In the case of adding a small amount of fluorine and iodine elements, the effect of forming a stable SEI film by the reaction of fluorine element with lithium and slowing down the migration speed of lithium ions by iodine element can be exerted.

[0040] The surface functionalization reaction of Cu and Ag metal clusters is as follows:

[0041] Oxidation-reduction reaction (the metal core is in the reduced state): Cu 0(Surface) + 2F - → CuF2 (surface);

[0042] Coordination-driven surface reconstruction: Ag 0 (Surface) + I - → AgI (surface).

[0043] The surface-functionalized metal core of the present invention comprises a metal core and a surface-functionalized layer, the metal core being selected from one or more of copper (Cu), silver (Ag), and gold (Au), and the surface-functionalized layer comprising fluorine element (F) and iodine element (I).

[0044] <Second aspect>

[0045] A lithium metal negative electrode containing surface-functionalized metal clusters is prepared by a method comprising the following steps:

[0046] S1. Perform surface treatment on the surface of the metal core to form a surface-functionalized layer, obtaining surface-functionalized metal clusters;

[0047] S2. Modify the surface-functionalized metal clusters on the surface of the lithium negative electrode, thereby obtaining a lithium metal negative electrode containing surface-functionalized metal clusters.

[0048] Preferably, step S2 is carried out under an inert gas protection environment.

[0049] Preferably, in step S2, the lithium negative electrode is pretreated: under an inert gas protection environment, mechanically scratch the surface of the lithium foil to remove the surface oxide layer and impurities.

[0050] Preferably, in step S2, the modification method includes one of coating, deposition, and in-situ growth.

[0051] Preferably, in step S2, the coating method includes one of spin coating, dip coating, spray coating, and blade coating. The coating method is preferably spin coating.

[0052] Preferably, in step S2, the coating is to disperse the surface-functionalized metal clusters in an aprotic polar solvent, and then coat the obtained dispersion on the surface of the lithium negative electrode. The aprotic polar solvent is selected from N-methylpyrrolidone (NMP), acetonitrile (ACN), dimethylformamide (DMF), or anhydrous diethyl ether, etc. The content of the surface-functionalized metal clusters in the dispersion is 0.1 - 0.2 g / 10 ml.

[0053] Preferably, in step S2, the lithium negative electrode is a lithium metal negative electrode or a lithium alloy negative electrode and its intercalation negative electrode material, preferably lithium foil.

[0054] Preferably, in step S2, the obtained lithium metal negative electrode comprises a substrate lithium metal negative electrode and a modified layer, and the modified layer comprises surface-functionalized metal clusters.

[0055] <Third aspect>

[0056] Application of a lithium metal anode containing surface-functionalized metal clusters in an all-solid-state lithium alloy secondary battery. The application of the surface-functionalized metal clusters for the lithium metal anode in an all-solid-state lithium alloy secondary battery with a lithium alloy as the anode also falls within the protection scope of the present invention.

[0057] An all-solid-state lithium metal secondary battery, comprising a solid electrolyte, a positive electrode, and the above-mentioned lithium metal anode containing surface-functionalized metal clusters.

[0058] Preferably, the solid electrolyte includes a polymer electrolyte, an oxide electrolyte, and a sulfide electrolyte.

[0059] Preferably, the positive electrode active material of the lithium metal battery is one of lithium iron phosphate, lithium cobaltate, lithium nickel cobalt manganate, lithium manganese phosphate, lithium titanate, lithium nickelate, and lithium manganate.

[0060] Compared with the all-solid-state lithium metal battery in the prior art, the beneficial effects of the present invention are as follows:

[0061] (1) Improving interfacial contact: In traditional all-solid-state lithium metal batteries, poor interfacial contact between the lithium metal anode and the solid electrolyte is a long-standing bottleneck problem. In the present invention, a surface-functionalized metal cluster layer containing fluorine and iodine elements is constructed on the surface of the lithium foil, effectively improving the interfacial contact between the lithium metal and the solid electrolyte. The metal clusters can increase the actual contact area and reduce the interfacial resistance.

[0062] (2) Suppressing side reactions: Lithium metal has extremely high chemical activity and is prone to side reactions with the solid electrolyte. The surface-functionalized metal cluster layer in the present invention can act as a "buffer layer", effectively isolating the lithium metal from the solid electrolyte, reducing or even suppressing the direct contact between the two, thereby reducing the occurrence of side reactions. For example, LiF formed by the reaction of fluorine with lithium helps to form a stable SEI film.

[0063] (3) Regulating ion transport and suppressing lithium dendrite growth: The ionic conductivity of the solid electrolyte is usually lower than that of the liquid electrolyte, and the ionic transport behavior at the interface is crucial for the performance of the lithium metal anode. In the present invention, the relatively large ionic radius of iodine can play a steric hindrance role during lithium deposition, slowing down the migration speed of lithium ions, thereby suppressing the rapid growth of lithium dendrites. The metal clusters themselves provide good electronic conductivity and promote the uniform transport of ions at the interface.

[0064] (4)The preparation method has certain universality and potential advantages for large-scale production: The present invention adopts a variety of mature preparation techniques (such as chemical reduction method, solvothermal method, microemulsion method and chemical vapor deposition method), which has certain universality and can achieve large-scale production by optimizing process parameters.

[0065] (5)Compatible with a variety of solid electrolytes: The metal clusters and functionalized layer materials used in the present invention usually have high chemical stability and electrochemical stability, and have good compatibility with various solid electrolytes (including polymers, oxides, sulfides, etc.), and can be widely applied to various all-solid-state lithium metal battery systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] By reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings, other features, objects and advantages of the present invention will become more apparent:

[0067] Figure 1 It is a cycling performance diagram of the surface-functionalized metal clusters of Example 1 applied to all-solid-state lithium metal;

[0068] Figure 2 It is a Coulomb efficiency diagram of the surface-functionalized metal clusters of Example 1 applied to all-solid-state lithium metal batteries;

[0069] Figure 3 It is a comparison diagram of the cycling performance of the all-solid-state lithium metal batteries of Example 1 and Comparative Example 1 of the present invention;

[0070] Figure 4 It is a schematic structural diagram of the metal clusters of the surface-functionalized layer of the present invention;

[0071] Figure 5 It is an XRD diffraction pattern of the copper nanoclusters and copper fluoride clusters in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0072] The present invention will be described in detail below with reference to the embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several adjustments and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0073] Example 1

[0074] This example provides a lithium metal negative electrode with a copper fluoride cluster layer. This example includes the following steps:

[0075] S1. Preparation of copper nanoclusters:

[0076] Add 50 mL of deionized water to a three-necked flask, heat it to 60 °C, and stir magnetically. Weigh 2.68 g of CuCl2·2H2O (0.015 mol), slowly add it to the hot water, and stir until completely dissolved to obtain a CuCl2 solution. Weigh 1.14 g of NaBH4 (0.03 mol), dissolve it in 20 mL of deionized water, and prepare a NaBH4 solution.

[0077] Under vigorous stirring, slowly add the NaBH4 solution dropwise to the CuCl2 solution. The color of the solution will quickly change from blue to brownish-black, indicating the formation of copper nanoclusters. Continue stirring for 30 minutes to allow the reaction to proceed fully.

[0078] Reaction equation (simplified): CuCl2 + NaBH4 → Cu + H2 + NaCl + B(OH)3

[0079] After standing for a period of time, centrifuge the product, and wash it three times with deionized water and anhydrous ethanol each to remove residual ions and by-products. Dry the washed product in a vacuum drying oven at 60 °C for 12 hours to obtain copper nanoclusters (particle size about 2 nm).

[0080] S2. Surface fluorination treatment:

[0081] In a glove box, disperse 0.5 g of the dried copper nanoclusters in 50 mL of anhydrous ethanol, and ultrasonically treat for 30 minutes to make them evenly dispersed.

[0082] Weigh 0.84 g of NaF (0.02 mol), dissolve it in 20 mL of deionized water, and prepare a NaF solution.

[0083] Under stirring, slowly add the NaF solution dropwise to the copper nanocluster dispersion.

[0084] Continue to stir in the glove box for 24 hours to allow the fluorination reaction to proceed fully.

[0085] S3. Post-treatment:

[0086] Take out the reaction mixture from the glove box and centrifuge the product.

[0087] Wash it three times alternately with anhydrous ethanol and deionized water to remove residual NaF and by-products.

[0088] Dry the washed product in a vacuum drying oven at 60 °C for 12 hours to obtain fluorinated copper clusters.

[0089] S4. Preparation of cluster dispersion:

[0090] Disperse 0.1 g of the dried fluorinated copper clusters in 10 ml of anhydrous ethanol, and ultrasonically treat to obtain a homogeneous dispersion.

[0091] S5. Lithium sheet pretreatment:

[0092] In the glove box, scrape off the oxide layer on the surface of the lithium sheet with a scraper.

[0093] S6. Spin coating:

[0094] Drop the copper fluoride cluster dispersion on the surface of the lithium sheet and spin coat it at a speed of 1000 rpm for 30 seconds to uniformly coat the dispersion on the surface of the lithium sheet.

[0095] S7. Drying:

[0096] Dry the coated lithium sheet in a vacuum drying oven in the glove box at 60 °C for 2 hours.

[0097] Figure 5 Figure 2 shows the XRD diffraction patterns of the copper nanoclusters and copper fluoride clusters in Example 1. The characteristic peaks of the XRD diffraction pattern of the copper fluoride clusters are consistent with those of the nanocopper clusters, with a slight shift to the right, indicating that fluorine has entered the copper lattice, resulting in lattice contraction, but both are of the cubane structure.

[0098] Example 2

[0099] This example provides a lithium metal negative electrode with a silver fluoride cluster layer. This example includes the following steps:

[0100] S1. Preparation of silver nanoclusters

[0101] Add 50 mL of deionized water to a three-necked flask, heat it to 60 °C, and stir magnetically. Weigh 0.17 g of AgNO3 (0.001 mol) and slowly add it to the hot water, stirring until completely dissolved to obtain an AgNO3 solution. Weigh 0.17 g of KI (0.001 mol) and dissolve it in 50 mL of deionized water to prepare a KI solution. Weigh 0.1 g of PVP (as a stabilizer) and dissolve it in 20 mL of deionized water to prepare a 0.5 wt% PVP solution.

[0102] Under vigorous stirring, slowly add the KI solution to the AgNO3 / PVP mixed solution. The color of the solution will quickly change from colorless to yellow and turbid, indicating the formation of AgI nanoclusters. Continue stirring for 30 minutes to allow the reaction to proceed fully.

[0103] After standing for a period of time, centrifuge the product, wash the precipitate three times with deionized water to remove residual KNO3 and PVP. Dry the washed product in a vacuum drying oven at 60 °C for 12 hours to obtain silver nanoclusters (particle size about 2 nm).

[0104] S2. Surface fluorination treatment

[0105] In the glove box, 0.5 g of dried silver nanoclusters were dispersed in 50 mL of absolute ethanol and sonicated for 30 minutes to achieve uniform dispersion. 0.84 g of NaF (0.02 mol) was weighed and dissolved in 20 mL of deionized water to prepare a NaF solution.

[0106] Under stirring, the NaF solution was slowly added dropwise to the silver nanocluster dispersion. Stirring was continued in the glove box for 24 hours to allow the fluorination reaction to proceed fully.

[0107] S3. Post-treatment

[0108] The reaction mixture was taken out of the glove box and the product was separated by centrifugation. It was washed three times alternately with absolute ethanol and deionized water to remove residual NaF and by-products. The washed product was dried in a vacuum drying oven at 60 °C for 12 hours to obtain silver fluoride clusters.

[0109] S4. Preparation of cluster dispersion

[0110] 0.1 g of dried silver fluoride clusters were dispersed in 10 mL of absolute ethanol and sonicated for 30 minutes to obtain a uniform dispersion.

[0111] S5. Lithium foil pretreatment

[0112] In the glove box, the oxide layer on the surface of the lithium foil was scraped off with a spatula.

[0113] S6. Spin coating

[0114] The silver fluoride cluster dispersion was dropped onto the surface of the lithium foil and spin-coated at a speed of 1000 rpm for 30 seconds to uniformly coat the dispersion on the surface of the lithium foil.

[0115] S7. Drying

[0116] The coated lithium foil was dried in a vacuum drying oven in the glove box at 60 °C for 2 hours.

[0117] Example 3

[0118] This example provides a lithium metal anode with a copper iodide cluster layer, and this example includes the following steps:

[0119] S1. Same as Example 1.

[0120] S2. Surface iodination treatment

[0121] In the glove box, 0.5 g of dried copper nanoclusters were dispersed in 50 mL of absolute ethanol and sonicated for 30 minutes to achieve uniform dispersion. 0.83 g of KI (0.005 mol) was weighed and dissolved in 20 mL of deionized water to prepare a KI solution.

[0122] While stirring, slowly add the KI solution dropwise to the copper nanocluster dispersion. Continue stirring in the glove box for 24 hours to allow the iodination reaction to proceed fully.

[0123] S3. Post-treatment

[0124] Take out the reaction mixture from the glove box and centrifuge to separate the product. Wash it three times alternately with absolute ethanol and deionized water to remove the residual KI and by-products. Dry the washed product in a vacuum drying oven at 60 °C for 12 hours to obtain copper iodide clusters.

[0125] S4. Preparation of cluster dispersion

[0126] Disperse 0.1 g of the dried copper iodide clusters in 10 mL of absolute ethanol and sonicate for 30 minutes to obtain a homogeneous dispersion.

[0127] S5. Lithium foil pretreatment

[0128] In the glove box, scrape off the oxide layer on the surface of the lithium foil with a spatula.

[0129] S6. Spin coating

[0130] Drop the copper iodide cluster dispersion on the surface of the lithium foil and spin coat at a speed of 1000 rpm for 30 seconds to uniformly coat the dispersion on the surface of the lithium foil.

[0131] S7. Drying

[0132] Dry the coated lithium foil in a vacuum drying oven in the glove box at 60 °C for 2 hours.

[0133] Comparative Example 1

[0134] This comparative example provides a lithium metal without a metal cluster layer; the steps are as follows

[0135] Prepare a lithium metal anode: commercial lithium copper composite tape (Tianjin Zhongneng Lithium Industry Co., Ltd.).

[0136] Comparative Example 2 (copper cluster layer)

[0137] This example provides a lithium metal anode with a copper cluster layer. The steps are basically the same as those in Example 1, except that: the prepared copper nanoclusters are not fluorinated and are directly coated.

[0138] Comparative Example 3 (copper fluoride layer)

[0139] This example provides a lithium metal anode with a copper fluoride layer. The steps are basically the same as those in Example 1, except that: directly take an equal amount of copper fluoride for dispersion and coating.

[0140] Performance test example

[0141] Assemble the products obtained from the above examples and comparative examples: In an inert gas glove box with a water and oxygen content ≤ 0.01 ppm, use Li6PS5Cl as the electrolyte layer, the positive electrode is a pole piece with a NCM811 loading of 10 mg cm -2 per unit area, and the surface-functionalized metal cluster lithium metal is used as the negative electrode layer to assemble a all-solid-state lithium metal battery. Finally, perform external pressure-free cyclic charge and discharge. First, charge and discharge at 0.1C for two cycles, and then perform long-term cyclic testing at 0.5C. Test its initial efficiency and the capacity retention rate after 500 cycles. The results are shown in Table 1 below:

[0142] As can be seen from Table 1, when using surface-functionalized metal cluster lithium metal, higher initial efficiency and capacity retention can be achieved, improving the performance of the all-solid-state lithium metal battery life. Figure 1 The excellent cyclic ability and capacity retention rate of Example 1 can be seen; Figure 2 Its excellent Coulomb efficiency can be seen. Figure 3 It can be seen that the cyclic ability of using surface-functionalized metal cluster lithium metal is significantly better than that of Comparative Example 1.

[0143] Table 1

[0144]

[0145] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A lithium metal anode containing surface functionalized metal clusters, characterized in that: Prepared by a method comprising the following steps: S1, performing surface treatment on the surface of the metal core to form a surface functionalized layer to obtain a surface functionalized metal cluster; S2, modifying the surface functionalized metal clusters on the surface of the lithium negative electrode, that is, obtaining a lithium metal negative electrode containing the surface functionalized metal clusters; In step S1, the surface treatment is fluorination and / or iodination treatment, and the composition of the surface functionalization layer is the corresponding metal fluoride and / or metal iodide; the metal core is a metal nanocluster with a cubane structure; the metal fluoride and / or metal iodide in the surface functionalization layer is a cubane structure; the metal of the metal core includes one or more of Cu, Ag, and Au; In step S2, the modification method includes one of coating and deposition.

2. The lithium metal negative electrode according to claim 1, characterized in that In step S1, the surface treatment step is: preparing a fluoride salt and / or an iodide salt into a salt solution, dropping it into the metal core dispersion, stirring and reacting, and obtaining a surface functionalized metal cluster.

3. The lithium metal negative electrode according to claim 2, characterized in that The mass ratio of the metal core to the fluoride salt and / or the iodide salt is 1:1-3; and / or, the fluoride salt comprises one or more of LiF, NaF, and AgF; and / or, the iodide salt comprises one or more of LiI, NaI, KI; and / or, the saline solution has a solubility of 0.01-0.1 g / ml; And / or, the content of the metal core in the metal core dispersion is 0.01-0.05 g / ml.

4. The lithium metal negative electrode according to claim 1, characterized in that In step S2, the coating method includes one of spin coating, dip coating, spray coating, and scraper coating.

5. The lithium metal negative electrode according to claim 1, characterized in that In step S2, the coating is to disperse the surface functionalized metal clusters in a non-protonic polar solvent, and then coat the obtained dispersion on the surface of the lithium negative electrode; The aprotic polar solvent includes one or more of N-methylpyrrolidone, acetonitrile, dimethylformamide, and anhydrous ether.

6. Use of the lithium metal negative electrode as claimed in claim 1 in an all-solid-state lithium alloy secondary battery.

7. An all-solid-state lithium metal secondary battery, characterized in that: The invention comprises a solid electrolyte, a positive electrode and the lithium metal negative electrode as claimed in claim 1.

8. The all-solid-state lithium metal secondary battery according to claim 7, characterized in that: The solid electrolyte includes one of a polymer electrolyte, an oxide electrolyte, and a sulfide electrolyte; And / or, the active material of the positive electrode includes one of lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium manganese phosphate, lithium titanate, lithium nickel oxide, and lithium manganese oxide.

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