Preparation method of three-dimensional current collector, three-dimensional current collector, negative electrode and battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly provides a preparation method of a three-dimensional current collector, the three-dimensional current collector, a negative electrode and a battery, and the preparation method comprises the following steps: mixing metal copper with specific metal to obtain an alloy mixture; the alloy mixture is heated and stirred to be subjected to solid solution or alloying, and a solid solution or alloy is obtained; the solid solution or the alloy is subjected to calendering treatment, and solid solution foil or alloy foil is obtained; and putting the foil into a specific solvent to carry out solid solution removal or dealloying treatment, so that the non-copper metal in the components reacts with the specific solvent to generate gas or precipitate, and the gas or precipitate is separated from the surface of the metal copper to obtain the three-dimensional current collector with a porous structure. Compared with the traditional preparation process of the three-dimensional current collector, the preparation method disclosed by the invention is simple in process, short in production flow period and suitable for commercial large-scale batch production.

Description

Technical Field

[0001] The present application relates to the technical field of lithium ion batteries, and in particular, to a preparation method of a three-dimensional current collector, a three-dimensional current collector, a negative electrode, and a battery. Background Art

[0002] In recent years, the rapid development of mobile devices, electric vehicles, and smart grids has attracted a great deal of attention and research on secondary batteries with high energy density, especially the research on secondary batteries such as lithium ion batteries, sodium ion batteries, and lithium air batteries. A battery generally includes a metal negative electrode, a positive electrode (such as a ternary positive electrode, a sulfur positive electrode, an oxygen positive electrode), and a current collector, etc. The metal negative electrode has a relatively high theoretical specific capacity and a relatively low reduction potential.

[0003] However, the commercialization of secondary batteries based on lithium metal negative electrodes is difficult, and the main reasons are as follows: one is the generation of lithium dendrites during repeated charge and discharge; the other is the reaction between metallic lithium and the electrolyte, resulting in a low Coulombic efficiency during the charge and discharge process. Lithium dendrites will pierce the separator, leading to battery short circuit and thermal runaway, and even explosion. Moreover, a low Coulombic efficiency requires a large amount of additional lithium to compensate for the loss of metallic lithium during the charge and discharge process. Therefore, since the 1960s, strategies for suppressing the growth of lithium dendrites have been proposed: the design of current collector materials and the regulation of structures. The traditional negative electrode current collector is copper foil. During the deposition process of metallic lithium, it is very easy to deposit unevenly, resulting in the growth of lithium dendrites. Therefore, a way to change the deposition mode of metallic lithium to eliminate lithium dendrites by constructing a new current collector has been explored. The current collector with a 3D structure can increase the specific surface area of the current collector and reduce the current density, thereby achieving the purpose of eliminating lithium dendrites. In current research, copper foam is widely used as a 3D current collector, but its preparation process is complex and the material and labor costs are high, which limits its large-scale commercial production.

[0004] Therefore, there is an urgent need to provide a preparation method of a three-dimensional current collector, a three-dimensional current collector, a negative electrode, and a battery to solve the above-mentioned technical problems. Summary of the Invention

[0005] The present application provides a preparation method of a three-dimensional current collector, a three-dimensional current collector, a negative electrode, and a battery. This preparation method has a simple preparation process, a short production process cycle, and is more suitable for large-scale batch production in commercialization.

[0006] The first aspect of the present application provides a preparation method of a three-dimensional current collector, including the following steps:

[0007] Mix metallic copper with a specific metal to obtain an alloy mixture;

[0008] Heat and stir the alloy mixture to make it form a solid solution or alloy to obtain a solid solution or alloy;

[0009] Roll the solid solution or alloy to obtain a solid solution foil or an alloy foil;

[0010] Put the foil into a specific solvent for desolidification or dealloying treatment, so that the non-copper metal in the component reacts with the specific solvent to generate gas or precipitate and separate from the surface of copper metal to obtain a three-dimensional current collector with a porous structure.

[0011] In the technical solution provided by the present invention, after mixing copper metal with a specific metal, heat and stir to make it solid-solutionized or alloyed, and then put the solid solution or alloy into a specific solvent for desolidification or dealloying treatment, so that the non-copper metal in the component reacts with the specific solvent to generate gas or precipitate and separate from the surface of copper metal. During the separation process, the copper metal forms a porous shape, thereby obtaining a three-dimensional current collector. Compared with the prior art, this preparation method in the present application is simple to operate, and the porosity of the three-dimensional current collector can be adjusted by the mass ratio of the specific metal participating in the alloying, and the three-dimensional current collector can be produced at low cost, with high efficiency and repeatability, and is more suitable for large-scale commercial preparation.

[0012] In any implementation manner, the specific metal is one or more of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, and barium.

[0013] In the technical solution provided by the present invention, the specific metal is selected as one or more of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, and barium. By using the specific melting point properties of such metals, they can be removed after co-melting with copper metal through dealloying.

[0014] In any implementation manner, the mass ratio of the specific metal in the alloy mixture is 10-90%. Specifically, the mass ratio of the specific metal in the alloy mixture can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90% or a range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0015] In the technical solution provided by the present invention, by controlling the mass ratio of the specific metal in the alloy mixture within the above range, the porosity of the three-dimensional current collector can be controlled. In other words, the higher the mass ratio of the specific metal, the higher the porosity of the three-dimensional current collector. Therefore, the porosity of the three-dimensional current collector can be adjusted by the mass ratio of the specific metal participating in alloying.

[0016] In any embodiment, the temperature of the heating and stirring is 200-800 °C. Specifically, the temperature of the heating and stirring can be 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C, 290 °C, 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C, 370 °C, 380 °C, 390 °C, 400 °C, 410 °C, 420 °C, 430 °C, 440 °C, 450 °C, 460 °C, 470 °C, 480 °C, 490 °C, 500 °C, 510 °C, 520 °C, 530 °C, 540 °C, 550 °C, 560 °C, 570 °C, 580 °C, 590 °C, 600 °C, 610 °C, 620 °C, 630 °C, 640 °C, 650 °C, 660 °C, 670 °C, 680 °C, 690 °C, 700 °C, 710 °C, 720 °C, 730 °C, 740 °C, 750 °C, 760 °C, 770 °C, 780 °C, 790 °C, 800 °C or a range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable. The time of the heating and stirring is 5-60 min. Specifically, the time of the heating and stirring can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min, 43 min, 44 min, 45 min, 46 min, 47 min, 48 min, 49 min, 50 min, 51 min, 52 min, 53 min, 54 min, 55 min, 56 min, 57 min, 58 min, 59 min, 60 min or a range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0017] In the technical solution provided by the present invention, the higher the temperature of heating and stirring, the faster the rate of solid solution formation or alloying. Therefore, by controlling the temperature of heating and stirring within the above range, the rate of solid solution formation or alloying of the alloy mixture can be controlled; the longer the time of heating and stirring, the more sufficient the solid solution formation or alloying. Therefore, by controlling the time of heating and stirring within the above range, the degree of sufficiency of solid solution formation or alloying of the alloy mixture can be controlled.

[0018] In any embodiment, the rotation speed of the heating and stirring is 10 - 100 rmp. Specifically, the rotation speed of the heating and stirring can be 10 rmp, 11 rmp, 12 rmp, 13 rmp, 14 rmp, 15 rmp, 16 rmp, 17 rmp, 18 rmp, 19 rmp, 20 rmp, 21 rmp, 22 rmp, 23 rmp, 24 rmp, 25 rmp, 26 rmp, 27 rmp, 28 rmp, 29 rmp, 30 rmp, 31 rmp, 32 rmp, 33 rmp, 34 rmp, 35 rmp, 36 rmp, 37 rmp, 38 rmp, 39 rmp, 40 rmp, 41 rmp, 42 rmp, 43 rmp, 44 rmp, 45 rmp, 46 rmp, 47 rmp, 48 rmp, 49 rmp, 50 rmp, 51 rmp, 52 rmp, 53 rmp, 54 rmp, 55 rmp, 56 rmp, 57 rmp, 58 rmp, 59 rmp, 60 rmp, 61 rmp, 62 rmp, 63 rmp, 64 rmp, 65 rmp, 66 rmp, 67 rmp, 68 rmp, 69 rmp, 70 rmp, 71 rmp, 72 rmp, 73 rmp, 74 rmp, 75 rmp, 76 rmp, 77 rmp, 78 rmp, 79 rmp, 80 rmp, 81 rmp, 82 rmp, 83 rmp, 84 rmp, 85 rmp, 86 rmp, 87 rmp, 88 rmp, 89 rmp, 90 rmp, 91 rmp, 92 rmp, 93 rmp, 94 rmp, 95 rmp, 96 rmp, 97 rmp, 98 rmp, 99 rmp, 100 rmp or any range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] In the technical solution provided by the present invention, the faster the rotation speed of the heating and stirring, the more sufficient the solid solution formation or alloying. Therefore, by controlling the rotation speed of the heating and stirring within the above range, the degree of sufficiency of solid solution formation or alloying of the alloy mixture can be controlled.

[0020] In any embodiment, the pressure of the calendering process is 10-100 kPa. Specifically, the pressure of the calendering process can be 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, 15 kPa, 16 kPa, 17 kPa, 18 kPa, 19 kPa, 20 kPa, 21 kPa, 22 kPa, 23 kPa, 24 kPa, 25 kPa, 26 kPa, 27 kPa, 28 kPa, 29 kPa, 30 kPa, 31 kPa, 32 kPa, 33 kPa, 34 kPa, 35 kPa, 36 kPa, 37 kPa, 38 kPa, 39 kPa, 40 kPa, 41 kPa, 42 kPa, 43 kPa, 44 kPa, 45 kPa, 46 kPa, 47 kPa, 48 kPa, 49 kPa, 50 kPa, 51 kPa, 52 kPa, 53 kPa, 54 kPa, 55 kPa, 56 kPa, 57 kPa, 58 kPa, 59 kPa, 60 kPa, 61 kPa, 62 kPa, 63 kPa, 64 kPa, 65 kPa, 66 kPa, 67 kPa, 68 kPa, 69 kPa, 70 kPa, 71 kPa, 72 kPa, 73 kPa, 74 kPa, 75 kPa, 76 kPa, 77 kPa, 78 kPa, 79 kPa, 80 kPa, 81 kPa, 82 kPa, 83 kPa, 84 kPa, 85 kPa, 86 kPa, 87 kPa, 88 kPa, 89 kPa, 90 kPa, 91 kPa, 92 kPa, 93 kPa, 94 kPa, 95 kPa, 96 kPa, 97 kPa, 98 kPa, 99 kPa, 100 kPa or a range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.The thickness of the calendering treatment is 10-100 μm. Specifically, the thickness of the calendering treatment can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 55 μm, 56 μm, 57 μm, 58 μm, 59 μm, 60 μm, 61 μm, 62 μm, 63 μm, 64 μm, 65 μm, 66 μm, 67 μm, 68 μm, 69 μm, 70 μm, 71 μm, 72 μm, 73 μm, 74 μm, 75 μm, 76 μm, 77 μm, 78 μm, 79 μm, 80 μm, 81 μm, 82 μm, 83 μm, 84 μm, 85 μm, 86 μm, 87 μm, 88 μm, 89 μm, 90 μm, 91 μm, 92 μm, 93 μm, 94 μm, 95 μm, 96 μm, 97 μm, 98 μm, 99 μm, 100 μm or a range composed of any two of the above values. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0021] In the technical solution provided by the present invention, the greater the pressure of the calendering treatment, the thinner the calendering thickness. Therefore, by controlling the pressure of the calendering treatment within the above range, the thickness of the finally obtained foil can be controlled. The thinner the foil, the lighter it is.

[0022] In any embodiment, the specific solvent is one or more of water, ethanol, acetonitrile, tetrahydrofuran, carbon tetrachloride, and toluene.

[0023] In the technical solution provided by the present invention, the specific solvent is one or more of water, ethanol, acetonitrile, tetrahydrofuran, carbon tetrachloride, and toluene. By using such substances that do not react with the copper metal in the components, but can react with non-copper metals such as lithium in the components to generate gases or precipitates and separate from the surface of the copper metal, thereby making the copper metal porous. For example, a large number of bubbles are generated during the dealloying and / or desolidification process, and after these bubbles continuously break and separate from the surface of the copper metal, a corresponding porous structure is generated. And this type of solvent is conventional, easy to obtain, low in cost, and will not remain volatile on the surface of the foil, nor will other impurities be generated.

[0024] The second aspect of the present application provides a three-dimensional current collector, which is prepared by using the described preparation method, and the porosity of the three-dimensional current collector is 50-90%.

[0025] The third aspect of the present application provides a negative electrode, which includes the described three-dimensional current collector and a negative electrode active material layer located on one or both sides of the three-dimensional current collector.

[0026] The fourth aspect of the present application provides a battery, which includes the described negative electrode.

[0027] The beneficial effects at least include:

[0028] In the present application, after mixing metallic copper with a specific metal, heating and stirring are carried out to make it form a solid solution or alloy, and then the solid solution or alloy is placed in a specific solvent for desolidification or dealloying treatment, so that the non-copper metal in the component reacts with the specific solvent to generate gas or precipitate and separate from the surface of the metallic copper, thereby making the metallic copper form a porous shape, and finally obtaining a three-dimensional current collector; compared with the preparation process of traditional three-dimensional current collectors, the preparation process of this method in the present application is simple, the production process cycle is short, it is suitable for commercial large-scale batch production, and the three-dimensional current collector made by this method not only has the characteristics of a high specific surface area of a two-dimensional current collector, but also has a three-dimensional spatial distribution of a porous structure, can significantly reduce the interfacial resistance during charge and discharge, and can be used in traditional lithium-ion batteries, metal lithium batteries or solid-state metal lithium batteries. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings;

[0030] Figure 1 It is a schematic diagram of the preparation process of a method for preparing a three-dimensional current collector in an embodiment of the present application;

[0031] Figure 2 It is an X-ray diffraction pattern of the desolidified / dealloyed foil;

[0032] Figure 3 It is the cycle curve of the semi-solid state metal lithium battery assembled with the three-dimensional current collector prepared in Example 1;

[0033] Figure 4 It is the cycle curve of the semi-solid state metal lithium battery assembled with the three-dimensional current collector prepared in Comparative Example 1. Detailed Embodiments

[0034] The embodiments of the present disclosure will be further described in detail below in conjunction with the accompanying drawings and examples. The following detailed description of the examples and the drawings are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure, that is, the present disclosure is not limited to the described embodiments.

[0035] The "range" disclosed herein is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The ranges defined in this way can include or exclude the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present disclosure, unless otherwise specified, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0036] In the present disclosure, if there is no special indication, all the embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0037] In the present disclosure, if there is no special indication, all the technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0038] In the present disclosure, if there is no special indication, all the steps mentioned herein can be carried out sequentially or randomly, but preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0039] A preferred embodiment of the present application provides a method for preparing a three - dimensional current collector. Please refer to Figure 1As shown, the preparation method includes the following steps:

[0040] S201. Mix metallic copper with a specific metal to obtain an alloy mixture;

[0041] S202. Heat and stir the alloy mixture to make it form a solid solution or alloy to obtain a solid solution or alloy;

[0042] S203. Roll the solid solution or alloy to obtain a solid solution foil or alloy foil;

[0043] S204. Place the foil in a specific solvent for desolidification or dealloying treatment, so that the non-copper metal in the component reacts with the specific solvent to generate gas or precipitate and separate from the surface of the metallic copper to obtain a three-dimensional current collector with a porous structure.

[0044] In the embodiment of the present application, aiming at the problems in the prior art that the preparation process of the three-dimensional current collector is complex, the material and labor costs are high, and the large-scale industrial production is restricted, a preparation method of a three-dimensional current collector is proposed. In this preparation method, after mixing metallic copper with a specific metal, heat and stir it to make it form a solid solution or alloy, and then place the solid solution or alloy in a specific solvent for spontaneous reaction to achieve desolidification or dealloying treatment, so that the non-copper metal in the component reacts with the specific solvent to generate gas or precipitate and separate from the surface of the metallic copper, thereby making the metallic copper form a porous shape, and thus obtaining a three-dimensional current collector. The three-dimensional current collector prepared by this preparation method can be used in traditional lithium-ion batteries, metal lithium batteries or solid-state metal lithium batteries. And compared with the prior art, the preparation method of the present application is simple in operation, short in production process cycle, can produce the three-dimensional current collector at low cost, efficiently and reproducibly, and the porosity of the three-dimensional current collector can be adjusted, which is more suitable for commercial large-scale batch production.

[0045] In some embodiments, in S201, the specific metal is one or more of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, and barium. Utilizing the specific melting point properties of such specific metals, they can be co-melted with metallic copper and then removed through dealloying.

[0046] Furthermore, the mass ratio of the specific metal in the alloy mixture is 10-90%, for example, the mass ratio of the specific metal in the alloy mixture is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%. The porosity of the three-dimensional current collector can be adjusted by the mass ratio of the specific metal participating in the alloying.

[0047] In some embodiments, in S202, the temperature of heating and stirring is 200 - 800 °C. For example, the temperature of heating and stirring can be 200 °C, 250 °C, 300 °C, 350 °C, 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C, 800 °C; the time of heating and stirring is 5 - 60 min. For example, the time of heating and stirring can be 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min; the rotation speed of heating and stirring is 10 - 100 rmp. For example, the rotation speed of heating and stirring can be 10 rmp, 20 rmp, 25 rmp, 30 rmp, 35 rmp, 40 rmp, 45 rmp, 50 rmp, 55 rmp, 60 rmp, 65 rmp, 70 rmp, 75 rmp, 80 rmp, 85 rmp, 90 rmp, 95 rmp, 100 rmp. By controlling the temperature, time, and rotation speed of heating and stirring, the alloying rate and degree of completion can be controlled.

[0048] In some embodiments, in S203, the pressure of rolling treatment is 10 - 100 kPa. For example, the pressure of rolling treatment can be 10 kPa, 15 kPa, 20 kPa, 25 kPa, 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, 100 kPa; the thickness of rolling treatment is 10 - 100 μm. For example, the thickness of rolling treatment can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm. By controlling the pressure of rolling treatment, the rolling thickness of the obtained foil can be controlled.

[0049] In some embodiments, in S204, the specific solvent is one or more of water, ethanol, acetonitrile, tetrahydrofuran, carbon tetrachloride, and toluene. Such specific solvents are easily obtainable, have low costs, and do not leave volatile residues on the surface of the foil, nor do they produce other impurities.

[0050] The embodiments of the present invention further provide a three-dimensional current collector prepared by the above preparation method. The porosity of the three-dimensional current collector is 50 - 90%, and can be, for example, 50%, 60%, 70%, 80%, 90%, etc.

[0051] An embodiment of the present invention further provides a negative electrode (not shown in the figure), the negative electrode comprising the above-mentioned three-dimensional current collector and a negative electrode active material layer located on one or both sides of the three-dimensional current collector.

[0052] An embodiment of the present invention further provides a battery, the battery comprising the above-mentioned negative electrode, and the battery can be a lithium metal battery.

[0053] The present invention will be specifically described below through examples and comparative examples.

[0054] Example 1

[0055] Mix metallic copper with a specific metal such as metallic sodium to obtain an alloy mixture, and the mass ratio of metallic sodium in the alloy mixture is 50%; heat the alloy mixture to 200 °C and stir it at a rotation speed of 20 rmp for 30 min to make it form a solid solution; subject the solid solution to a rolling treatment under an external pressure of 20 kPa to obtain a foil with a thickness of 30 μm; place the foil in a specific solvent such as ethanol for desolidification treatment, so that the non-copper metal in the component reacts with ethanol to generate gas, thereby making the metallic copper form a porous shape, and thus obtaining a three-dimensional current collector.

[0056] Example 2

[0057] The difference from Example 1 is that in this example, the specific metal is metallic potassium.

[0058] Other steps are the same as those in Example 1 and will not be repeated here.

[0059] Example 3

[0060] The difference from Example 1 is that in this example, the mass ratio of metallic sodium in the alloy mixture is 70%.

[0061] Other steps are the same as those in Example 1 and will not be repeated here.

[0062] Example 4

[0063] The difference from Example 1 is that in this example, the heating temperature is 300 °C.

[0064] Example 5

[0065] The difference from Example 1 is that in this example, the heating time is 20 min.

[0066] Example 6

[0067] The difference from Example 1 is that in this example, the rolling pressure is 50 kPa.

[0068] Example 7

[0069] The difference from Example 1 is that in this example, the rolling thickness is 50 μm.

[0070] Example 8

[0071] Different from Example 1: The specific solvent in this example is acetonitrile.

[0072] Comparative Example 1

[0073] Different from Example 1, in Comparative Example 1, the three-dimensional current collector used in the semi-solid battery assembly is a conventional copper foam product.

[0074] Table 1. Specific processing conditions of Examples 1 - 8

[0075]

[0076] Effect Example

[0077] Furthermore, the battery performance of the three-dimensional lithium metal anodes prepared through the above-mentioned examples and comparative examples was further tested. The specific testing method is as follows:

[0078] Step 1. Assembly of semi-solid metal lithium battery

[0079] Using nickel cobalt manganese 622 ternary material as the positive active material, super-P as the conductive agent, and PVDF as the binder, with a ratio of 18:1:1 among the three, a positive electrode sheet was prepared. Using PEO and LLZO as the solid electrolyte materials, a composite solid electrolyte membrane was prepared according to a mass ratio of 3:1, using LiTFSI as the lithium salt, and a lithium-oxygen ratio of 1:15. Using the three-dimensional lithium metal of each example and comparative example as the negative electrode. Adding LB302 type electrolyte, and the electrolyte accounts for 10% of the total mass of the battery cell. The semi-solid battery was assembled with a mold battery, and the external pressure of the battery was 200 kPa.

[0080] Step 2. Testing of semi-solid metal lithium battery

[0081] After the battery was assembled, it was left standing for 240 min, and at room temperature (25 °C), charge-discharge tests were carried out at a rate of 0.33C.

[0082] The results of the first-cycle discharge specific capacity, first-cycle Coulombic efficiency, and 400-cycle capacity retention rate obtained through the above testing method for each example and comparative example are shown in Table 2.

[0083] Table 2 Results of the first-cycle discharge specific capacity, first-cycle Coulombic efficiency, and 400-cycle capacity retention rate of each example and comparative example

[0084] Example Initial cycle discharge specific capacity (mAh / g) Initial cycle Coulombic efficiency (%) Capacity retention rate after 400 cycles (%) Example 1 175.6 95.8 89.3 Example 2 175.3 95.9 88.6 Example 3 174.9 96.1 89.3 Example 4 175.7 95.6 87.7 Example 5 176.3 96.0 88.3 Example 6 174.9 94.9 87.2 Example 7 176.1 96.2 89.8 Example 8 175.5 95.3 88.1 Comparative example 1 175.7 95.9 76.2

[0085] Specifically, Figure 2The X-ray diffraction pattern of the desolvated foil is shown. Since metallic sodium has a high reactivity with ethanol while metallic copper does not react with ethanol, only the diffraction peaks of metallic copper are found in the X-ray pattern, the diffraction peaks of metallic sodium disappear, and no other impurity phases are generated, indicating that the desolvation reaction is relatively complete.

[0086] The electrochemical performance was evaluated by assembling semi-solid batteries. The first-cycle discharge specific capacity, first-cycle Coulombic efficiency, and 400-cycle capacity retention data of the semi-solid batteries assembled with the three-dimensional metallic lithium processed in Examples 1-8 and Comparative Example 1 at a rate of 0.33C are shown in Table 2 above. It can be seen from Table 2 that there is little difference in the first-cycle discharge specific capacity and first-cycle Coulombic efficiency among all Examples 1-8 and Comparative Example 1. Figure 3 The 0.33C cycling curve of the semi-solid battery assembled with the three-dimensional metallic lithium processed in Example 1 is shown, and its capacity retention rate can reach 89.3% after 400 cycles; Figure 4 The 0.33C cycling curve of the semi-solid battery assembled with the three-dimensional metallic lithium processed in Comparative Example 1 is shown, and its capacity retention rate is only 76.2% after 400 cycles. The difference in its electrochemical cycling performance can be inferred from the degree of expansion of the three-dimensional current collector structure. When metallic lithium is fully filled in the three-dimensional current collector, its volume change rate is maximally suppressed, and it has good electrochemical stability.

[0087] Therefore, on the one hand, the three-dimensional current collector prepared by the embodiments of the present application can increase the specific surface area of the current collector and reduce the current density, so as to achieve the purpose of eliminating lithium dendrites; on the other hand, it can make metallic lithium fully filled.

[0088] The above-described embodiments merely represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A preparation method of a three-dimensional current collector, characterized in that, It includes the following steps: Mix metallic copper with a specific metal to obtain an alloy mixture; Heat and stir the alloy mixture to make it form a solid solution or alloy, obtaining a solid solution or alloy; Roll the solid solution or alloy to obtain a solid solution foil or alloy foil; Put the foil into a specific solvent for desolidification or dealloying treatment, so that the non-copper metal in the components reacts with the specific solvent to generate gas or precipitate and separate from the surface of the metallic copper, obtaining a three-dimensional current collector with a porous structure.

2. The method for preparing the three-dimensional current collector according to claim 1, characterized in that The specific metal is one or more of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, and barium.

3. The method for preparing the three-dimensional current collector according to claim 1, characterized in that The mass ratio of the specific metal in the alloy mixture is 10-90%.

4. The method for preparing the three-dimensional current collector according to claim 1, characterized in that The temperature of the heating and stirring is 200-800°C; The time of the heating and stirring is 5-60 min.

5. The method for preparing the three-dimensional current collector according to claim 1, characterized in that The rotation speed of the heating and stirring is 10-100 rmp.

6. The method for preparing the three-dimensional current collector according to claim 1, characterized in that The pressure of the rolling treatment is 10-100 kPa; The thickness of the rolling treatment is 10-100 μm.

7. The method for preparing the three-dimensional current collector according to claim 1, characterized in that The specific solvent is one or more of water, ethanol, acetonitrile, tetrahydrofuran, carbon tetrachloride, and toluene.

8. A three-dimensional current collector, characterized in that, Prepared by using the preparation method according to any one of claims 1-7, the porosity of the three-dimensional current collector is 50-90%.

9. A negative electrode, characterized in that, It includes the three-dimensional current collector according to claim 8 and a negative electrode active material layer located on one or both sides of the three-dimensional current collector.

10. A battery, characterized in that, It includes the negative electrode according to claim 9.

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