Alloy and preparation method therefor and use thereof, porous material, current collector, secondary battery, and device

Abstract

The present invention provides an Mn-M binary multi-phase alloy, comprising: 39wt％≤Mn≤78wt％, and the remainder comprising a metal M, wherein the standard electrode potential of the metal M is higher than that of Mn, and an αMn phase, a γM-Mn phase, and a γ'Mn-M phase are distributed in the binary metallic multi-phase alloy. In addition, the present invention further relates to a preparation method for the Mn-M binary multi-phase alloy, a use thereof in preparation of a porous material, a current collector comprising the porous material, a secondary battery, and an electric device.

Description

Alloy, preparation method and use, porous material, current collector, secondary battery and device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure is based on the Chinese patent application with application number 202311460854.3, application date November 3, 2023, and invention name “Alloys and preparation methods and uses, porous materials, current collectors, secondary batteries and devices”, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into the present disclosure as a reference. Technical Field

[0003] The present disclosure relates to the technical field of metal materials, and in particular to a Mn-M binary multiphase alloy, a preparation method and uses thereof, a porous material, a current collector, a secondary battery and an electrical device. Background Art

[0004] Porous metal materials are a new class of multifunctional materials that have emerged in recent years with the rapid development of material preparation and machining technologies. Their inherent structural characteristics enable diversified functions and are widely used in fields such as electrode materials, automobiles, catalysis, and heat exchange. Currently, common porous metal materials are mainly prepared by dealloying precursor alloys. However, due to the microstructure distribution of the precursor alloys themselves, the resulting materials inevitably contain inherent defects such as grain boundaries and dislocations. Therefore, obtaining porous materials through dealloying, especially porous materials with a multi-level pore size distribution, still presents considerable challenges.

[0005] Therefore, there is a need to continuously develop new precursor materials in order to obtain improved porous materials with multi-level pore size distribution.

[0006] Summary of the Invention

[0007] The present disclosure addresses the aforementioned challenges and aims to provide a novel Mn-M binary multiphase alloy containing a distribution of αMn, γM-Mn, and γ'Mn-M phases. Through the coexistence of α, γ, and γ' phases, the disclosed multiphase alloy can form a porous material with varying pore sizes after dealloying corrosion. Furthermore, the pore size of the porous material can be effectively and relatively easily controlled by controlling the content and size of the α, γ, and γ' phases.

[0008] In a first aspect, the present disclosure provides a Mn-M binary metal multiphase alloy comprising: 39 wt% ≤ Mn ≤ 78 wt%, optionally 68 wt% ≤ Mn ≤ 78 wt%, with the remainder comprising metal M and unavoidable impurities; wherein the standard electrode potential of the metal M is higher than that of Mn, and the binary metal multiphase alloy comprises an αMn phase, a γM-Mn phase, and a γ'Mn-M phase. In the multiphase alloy of the present disclosure, the standard electrode potential of the metal M is higher than that of the Mn, so that during the dealloying process of the Mn-M alloy, the Mn is corroded and the M remains, ultimately forming a porous metal M material. Simultaneously, by setting the Mn content between 39 wt% and 78 wt%, optionally between 68 wt% and 78 wt%, a moderate corrosion rate can be maintained during the dealloying corrosion process, and the resulting porous structure has a porosity as high as possible while maintaining the pore continuity of the porous material. In addition, the binary alloy of the present invention contains αMn phase, γM-Mn phase and γ'Mn-M phase, and the sizes of these three phases differ by orders of magnitude, which enables the alloy to form a porous material with a multi-level pore size distribution through dealloying.

[0009] In any embodiment, the metal M is selected from one of Cu, Cr, Co, Sn, and Ni, and is optionally Cu. Binary alloys formed from these metals M and Mn, after dealloying, yield corresponding porous Cu materials, porous Cr materials, porous Co materials, porous Sn materials, and porous Ni materials having a multi-level pore size distribution. These porous materials can be widely used in fields such as energy, environment, and biomedicine.

[0010] In any embodiment, the multiphase alloy includes quasi-equiaxed grains, optionally having an average size of 5 μm to 30 μm, optionally 10 μm to 25 μm. The grains and grain size in the multiphase alloy affect the mechanical properties and processing properties of the alloy. By having quasi-equiaxed grains within this range, the multiphase alloy of the present disclosure will have an appropriate degree of plasticity and hardness, making it easy to process.

[0011] In any embodiment, the grains of the multiphase alloy have grain boundaries with discontinuous distribution of metal Mn and metal M. The discontinuous distribution of Mn and metal M in the grain boundaries effectively forms a continuous skeleton of metal M after corrosion, resulting in a porous metal M material with a relatively regular pore size distribution.

[0012] In any embodiment, the αMn phase comprises 4.6 wt% to 65.6 wt% of the multiphase alloy, and optionally, the αMn phase comprises >99 wt% of the Mn element. After the Mn element in the αMn phase is completely or substantially completely removed during the dealloying process, the αMn phase substantially disappears, and a pore structure having a first pore size (hereinafter referred to as macropores) is correspondingly formed in its place. Within the scope of the present disclosure, the αMn phase can form a moderate proportion of macropores in the porous material.

[0013] In any embodiment, the γM-Mn phase and the γ'Mn-M phase together account for 34.4 wt% to 95.3 wt% of the multiphase alloy, and optionally, the M content of the γM-Mn phase is 35 wt% to 100 wt%, and the Mn content of the γ'Mn-M phase is 62 wt% to 72 wt%. The γM-Mn phase is a M-rich phase. During subsequent corrosion by a dealloying method, only the Mn element contained therein is removed, while the M metal contained therein remains, thereby increasing the strength of the etched edge diameter. The γ'Mn-M alloy is a Mn-rich phase. During subsequent corrosion by a dealloying method, after the Mn element in the γ'Mn-M phase is removed, the Mn metal in the phase disappears, while the M metal remains, and a pore structure with a second pore size (hereinafter referred to as a small pore) is formed at the Mn in the γ'Mn-M phase.

[0014] In a second aspect, the present disclosure provides a method for preparing a Mn-M binary metal multiphase alloy, comprising:

[0015] Smelting Mn and metal M in a weight ratio of (39-78):(22-61), optionally (68-78):(22-32), to obtain a Mn-M binary alloy, wherein the standard electrode potential of the metal M is higher than the standard electrode potential of Mn;

[0016] performing a first heat treatment on the obtained Mn-M binary alloy to obtain a first product including a γMn-M solid solution;

[0017] performing a second heat treatment on the first product to crystallize the first product to obtain a second product;

[0018] performing a third heat treatment on the second product to obtain a third product including a γM-Mn phase and a γ'Mn-M phase; and

[0019] The third product is subjected to a fourth heat treatment to obtain a binary multiphase alloy including an αMn phase, a γM-Mn phase, and a γ′Mn-M phase.

[0020] By the preparation method disclosed in the present invention, a Mn—M binary multiphase alloy including an αMn phase, a γM-Mn phase, and a γ′Mn-M phase can be specifically prepared.

[0021] In any embodiment, the method includes one or more of the following features: the first heat treatment is a homogenization heat treatment; the temperature of the first heat treatment is 720°C to 900°C; the duration of the first heat treatment is 12 hours to 24 hours; and the alloy is subjected to plastic working after the first heat treatment. This first heat treatment can reduce dendritic segregation formed during the casting process, which can cause Mn and metallic M to segregate in an irregular manner, hindering the formation of regular porosity.

[0022] In any embodiment, the method further includes one or more of the following features: the second heat treatment is a recrystallization treatment; the temperature of the second heat treatment is 720°C to 800°C; and the duration of the second heat treatment is 0.5 to 6 hours. This second heat treatment produces quasi-equiaxed alloy grains. This second heat treatment, i.e., recrystallization, eliminates the rolling orientation of the material along the rolling direction, resulting in uniformly distributed pores along the length after dealloying corrosion, without the presence of stripe-shaped corrosion pits or pores parallel to the length.

[0023] In any embodiment, the method further includes one or more of the following features: the third heat treatment is a spinodal decomposition treatment; the temperature of the third heat treatment is 400°C to 500°C; and the duration of the third heat treatment is 0.5 to 4 hours. Through this third heat treatment, the second product undergoes phase decomposition to produce a third product comprising a γM-Mn phase and a γ'Mn-M phase. The M-rich γ phase can improve the strength of the edge diameter after dealloying.

[0024] In any embodiment, the method further includes one or more of the following features: the fourth heat treatment is a phase separation treatment; the temperature of the fourth heat treatment is 600°C to 680°C; and the duration of the fourth heat treatment is 1 hour to 6 hours. Through this fourth heat treatment, an αMn phase can be precipitated, and by regulating the temperature and duration of the treatment, the proportion and size of the αMn phase can be controlled, thereby achieving control over the proportion and pore size of pores having the first pore size in the porous material. For example, the lower the fourth heat treatment temperature, the higher the proportion of the αMn phase.

[0025] In a third aspect, the present disclosure provides a use of the multiphase alloy of the first aspect and the multiphase alloy prepared in the second aspect in preparing a porous material. Optionally, the porous material is used as a current collector in a battery.

[0026] In a fourth aspect, the present disclosure provides a porous material, which is obtained by dealloying the multiphase alloy of the first aspect and the multiphase alloy prepared in the second aspect of the present disclosure in the preparation of the porous material, wherein the porous material has pores with a first pore size and a second pore size, the first pore size is n microns, where 0.5≤n≤10, optionally 2≤n≤5, and the second pore size is m nanometers, where 20<m<200, optionally, 40<m<70.

[0027] In a fifth aspect, the present disclosure provides a current collector comprising the porous material described in the fourth aspect.

[0028] In a sixth aspect, the present disclosure provides a secondary battery comprising the current collector described in the fifth aspect.

[0029] In a seventh aspect, the present disclosure provides an electrical device comprising the secondary battery described in the sixth aspect.

[0030] In the present disclosure, by setting the content of Mn metal in the alloy to 39wt%-78wt%, when a porous structure is obtained by the dealloying method, a higher porosity is obtained as much as possible while maintaining the stability of the porous skeleton, and the corrosion rate will not be too fast or too slow to affect the pore continuity of the porous material. In addition, by distributing needle-shaped α phase and γ phase (M-rich phase) and γ' phase (Mn-rich phase) inside the alloy grains, a porous material with different pore distributions (such as micron and nano pore sizes) can be obtained by the dealloying method. In addition, by controlling the ratio and size of the α phase and the γ phase (M-rich phase) and the γ' phase (Mn-rich phase), the pore size and ratio of the pores with the first pore size and the pores with the second pore size in the porous material can be flexibly adjusted. For example, by adjusting the temperature and time of the fourth heat treatment, the ratio and size of the αMn phase in the alloy can be controlled, and then the ratio and pore size of the pores with the first pore size in the porous material can be controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1A is a metallographic photograph of the binary multiphase alloy prepared in Example 3.

[0032] FIG1B is a backscattered photograph of the binary multiphase alloy prepared in Example 3. FIG.

[0033] FIG2 is an XRD pattern of the binary multiphase alloy prepared in Example 3.

[0034] 3A and 3B are scanning electron microscope images of the binary multiphase alloy of Example 3 after dealloying.

[0035] FIG4 is a photo of the precursor prepared in Comparative Example 1.

[0036] FIG5 is a scanning photograph of the alloy of Comparative Example 1 after dealloying as a precursor.

[0037] FIG6 is a phase diagram of a Mn-Cu binary alloy.

[0038] FIG. 7 is a schematic diagram of a secondary battery according to an embodiment of the present disclosure.

[0039] FIG. 8 is an exploded view of the secondary battery according to the embodiment of the present disclosure shown in FIG. 7 .

[0040] FIG. 9 is a schematic diagram of a battery module according to an embodiment of the present disclosure.

[0041] FIG. 10 is a schematic diagram of a battery pack according to an embodiment of the present disclosure.

[0042] FIG. 11 is an exploded view of the battery pack shown in FIG. 10 according to one embodiment of the present disclosure.

[0043] FIG. 12 is a schematic diagram of an electric device using a secondary battery according to an embodiment of the present disclosure as a power source.

[0044] Description of reference numerals:

[0045] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 top cover assembly DETAILED DESCRIPTION

[0046] Hereinafter, the embodiments of the multiphase alloy, its preparation method and use, porous material, current collector, secondary battery and device disclosed in the present invention will be described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the claims.

[0047] " scope " disclosed in the present disclosure is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and selected lower limit and upper limit define the boundary of special scope.The scope that this mode limits can be to include end value or not include end value, and can be combined arbitrarily, and promptly any lower limit can form a scope with any upper limit combination.For example, if the scope of 60-120 and 80-110 is listed for specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.In the present disclosure, unless otherwise specified, numerical range " ab " represents the abbreviation of any real number combination between a and b, and wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] Unless otherwise indicated, the following terms used in the specification and claims have the following meanings.

[0049] The "standard electrode potential" mentioned herein refers to the equilibrium potential measured when the temperature is 25°C and the effective concentration of the metal ion is 1 mol / L (i.e., the activity is 1), which reflects the redox ability of the substance. The standard electrode potential of Mn is -1.18V. Metals with a standard electrode potential higher than that of Mn refer to metals with a standard electrode potential more positive than -1.18V, such as Co (-0.277V), Ni (-0.25V), Sn (+0.15V), Cu (+0.337V), and Cr (+1.64V). The standard electrode potentials of various metals are well known in the art and will not be described in detail here. The difference in standard electrode potential between Mn and metal M enables, when preparing porous materials by dealloying, most or even all of the Mn element to be removed from the αMn, γM-Mn phase, and γ'Mn-M phase, while very little or no M element is removed.

[0050] The "αMn phase" mentioned herein refers to an allotrope of Mn with a body-centered cubic (bcc) structure.

[0051] "γM" referred to herein refers to an allotrope of M having a face-centered cubic (fcc) structure.

[0052] The "γMn" mentioned herein refers to an allotrope of Mn having a face-centered cubic (fcc) structure.

[0053] The "γM-Mn phase" mentioned herein refers to a solid solution phase formed by Mn dissolving in γM. In some embodiments, the content of M element in the γM-Mn phase is 35 wt% to 100 wt%.

[0054] The "γ'Mn-M phase" mentioned herein refers to a solid solution phase formed by M dissolving in γMn. In some embodiments, the content of Mn element in the γ'Mn-M phase is 60 wt% to 74 wt%.

[0055] The "solid solution" mentioned herein refers to a single-phase crystalline solid formed by one or more solute components dissolving into a crystalline solvent while maintaining the lattice type of the solvent.

[0056] The "quasi-equiaxed grains" mentioned herein have grains with relatively small size differences in various directions.

[0057] The "dealloying method" referred to herein refers to the selective removal of relatively active metal atoms in a system based on the difference in standard electrochemical potential between the metals in the system, while the remaining metal atoms are interconnected to form a porous material. For example, the dealloying method includes chemical etching, electrochemical etching, or a combination thereof, but is not limited thereto.

[0058] The term "metallographic photograph" used in this article refers to a microscopic photograph that reflects the metal's microstructure, especially its phase distribution. Metallographic photographs can be taken using an optical microscope or an electron microscope.

[0059] Unless otherwise specified, all embodiments and optional embodiments of the present disclosure can be combined with each other to form new technical solutions.

[0060] Unless otherwise specified, all technical features and optional technical features disclosed herein can be combined with each other to form a new technical solution.

[0061] Unless otherwise specified, all steps of the present disclosure may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0062] As mentioned above, porous metal materials are a combination of structural materials and functional materials. They integrate multiple properties such as electrical properties, permeability, damping properties and flow properties, and have advantages in application that traditional materials cannot match. At present, the demand and requirements for porous materials with multi-level pore size distribution are increasing, so the preparation of such porous materials has also attracted more and more attention. Previously, common porous metal materials were mainly prepared by dealloying. However, due to the uneven composition of the precursor alloy, the material inevitably has inherent defects such as grain boundaries and dislocations, resulting in the acquisition of porous materials with multi-level pore size distribution after dealloying treatment. There are still considerable challenges. Therefore, there is still a need to develop new precursor materials to be able to prepare improved porous materials with multi-level pore size distribution.

[0063] The present disclosure provides a Mn-M binary multiphase alloy material with an improved structure, particularly a Mn-Cu alloy material, by changing the composition and phase of the precursor alloy material. The present invention and preferred embodiments are described in more detail below.

[0064] [Mn-M binary multiphase alloy]

[0065] The "Mn-M binary multiphase alloy" mentioned herein refers to an alloy comprising Mn and metal M, having two or more metal phases at room temperature. The "metal phase" mentioned herein includes, for example, α phase, β phase, and γ phase, but is not limited thereto.

[0066] In some embodiments, the present disclosure provides a Mn-M binary multiphase alloy, the multiphase alloy comprising: 39 wt% ≤ Mn ≤ 78 wt%, optionally, 68 wt% ≤ Mn ≤ 78 wt%, with the remainder comprising metal M; wherein the standard electrode potential of the metal M is higher than the standard electrode potential of Mn, and the binary metal multiphase alloy is distributed with αMn phase, γM-Mn phase, and γ'Mn-M phase. It should be understood that the binary multiphase alloy of the present disclosure also contains unavoidable impurities. Here, as unavoidable impurities, although Mg, Al, Si, Ag, Ca, S, O, C, Be, N, H, B, Zr, rare earths, etc. can be listed, the total amount of these unavoidable impurities is preferably less than 0.1 wt%. The weight percentages, i.e., wt%, involved in the present disclosure are determined by atomic fluorescence spectrometry, which is well known in the art.

[0067] In the present disclosure, by 39wt%≤Mn≤78wt%, optionally, 68wt%≤Mn≤78wt%, when a porous structure is obtained by a dealloying method, a high porosity can be obtained as much as possible while maintaining the stability of the porous skeleton, and the corrosion rate will not be too fast or too slow to affect the pore continuity performance of the porous material. Due to the order of magnitude difference in size between the αMn phase, γM-Mn phase and γ'Mn-M phase, when the porous material is subsequently prepared, the α phase will form pores with a pore size of 0.5μm to 10μm after dealloying corrosion, and the γ phase and γ' phase will form pores with a pore size of 20nm to 200nm, thereby forming a porous material with a multi-level pore size distribution.

[0068] In some embodiments, the metal M may be selected from one of Cu, Cr, Co, Sn, and Ni. In some embodiments, the metal M is Cu. For example, the alloys formed by these metal elements and Mn after dealloying may yield corresponding materials with multi-level pore size distributions such as porous Cu materials, porous Cr materials, porous Co materials, porous Sn materials, and porous Ni materials. These porous metal materials are widely used in fields such as energy, environment, and biomedicine. Specifically, porous Cu materials and porous Ni are used as current collectors in batteries, and porous Sn is used in the field of catalysis.

[0069] In some embodiments, the multiphase alloy includes quasi-equiaxed grains. In practice, after being rolled into foil, the material forms a rolling orientation along the rolling direction. This rolling orientation can lead to uneven porosity distribution along the length after corrosion, resulting in stripe-shaped corrosion pits or pores parallel to the length. Quasi-equiaxed grains, on the other hand, prevent porosity from being oriented solely in the rolling direction after corrosion, thus preventing stripe-shaped corrosion pits or pores parallel to the length during subsequent corrosion.

[0070] In some embodiments, the multiphase alloys disclosed herein include quasi-equiaxed grains with an average size of 5 μm to 30 μm, optionally 10 μm to 25 μm. This grain size is determined by placing the sample under a metallographic microscope to obtain the metallographic structure, counting the sizes of 50 grains, and then taking the average. The grain size and mechanical properties of a multiphase alloy are crucial for its processing. By maintaining quasi-equiaxed grains within this range, the multiphase alloys disclosed herein possess suitable plasticity and hardness, making them easier to process.

[0071] In some embodiments, the grains of the multiphase alloy have grain boundaries where metal Mn and metal M are discontinuously distributed. The discontinuously distributed grain boundaries of Mn and metal M effectively form a continuous skeleton of metal M after corrosion, resulting in a porous metal M material with a relatively regular pore size distribution. Thus, the presence of the continuous grain boundaries of Mn does not lead to collapse of the porous structure during corrosion, nor does the presence of the continuous grain boundaries of metal M result in the porous material being free of pores in localized areas.

[0072] In some embodiments, the αMn phase comprises 4.6 wt% to 65.6 wt% of the multiphase alloy. After the Mn element in the αMn phase is completely or substantially completely removed, the αMn phase disappears completely or substantially completely, and a pore structure having a first pore size (hereinafter referred to as macropores) is correspondingly formed in its place. The αMn phase within the scope of the present disclosure can form a moderate proportion of macropores.

[0073] In some embodiments, the content of Mn in the αMn phase is greater than 99 wt %, such as 99.1 wt %, 99.2 wt %, 99.3 wt %, 99.4 wt %, 99.5 wt %, 99.6 wt %, 99.7 wt %, 99.8 wt %, or 99.9 wt %. Advantageously, based on the total Mn in the αMn phase, at least 89 wt %, such as at least 95 wt %, or at least 99 wt %, of the Mn is removed from the αMn phase by dealloying. The resulting porous material thus has a first pore size of n microns, where 0.5 ≤ n ≤ 10, for example, n is 0.5-1, 1-5, 5-10, 2-8, or 2-7, and optionally 2 ≤ n ≤ 5.

[0074] In some embodiments, the γM-Mn phase and the γ'Mn-M phase together account for 34.4 wt% to 95.3 wt% of the multiphase alloy. In some embodiments, the M content of the γM-Mn phase is 35 wt% to 100 wt%. The γM-Mn phase is a M-rich phase. During subsequent corrosion by dealloying, only the Mn element is removed, while the M metal remains, thereby increasing the strength of the etched edge.

[0075] In some embodiments, the content of Mn in the γ'Mn-M phase is 60 wt% to 72 wt%. The γ'Mn-M alloy is a Mn-rich phase. When the Mn in the γ'Mn-M phase is subsequently corroded by a dealloying method, the Mn metal in the phase disappears after the Mn is removed, while the M metal is retained, and a pore structure with a second pore size (hereinafter referred to as a small pore) is correspondingly formed at the Mn in the γ'Mn-M phase. Advantageously, based on the total Mn in the γ'Mn-M phase, at least 89 wt%, for example, more than 94 wt%, of the Mn is removed from the γ'Mn-M phase by a dealloying method. Based on this, the obtained porous material has a second pore size, which is m nanometers, for example, 20 < m < 200. Optionally, the value of m is 20-50, 50-100, 100-150, or 150-200, and optionally, 40 < m < 70. Thus, together with the macropores formed after the αMn phase is corroded, a porous material with a multi-level pore size distribution is formed.

[0076] [Preparation method]

[0077] In an embodiment of the present disclosure, a method for preparing a Mn—M binary multiphase alloy is provided.

[0078] The method comprises:

[0079] Smelting Mn and metal M in a weight ratio of (39-78):(22-61), optionally (68-78):(22-32), to obtain a Mn-M binary alloy, wherein the standard electrode potential of the metal M is higher than the standard electrode potential of Mn;

[0080] performing a first heat treatment on the obtained Mn-M binary alloy to obtain a first product including a γMn-M solid solution;

[0081] performing a second heat treatment on the first product to crystallize the first product to obtain a second product;

[0082] performing a third heat treatment on the second product to obtain a third product including a γM-Mn phase and a γ'Mn-M phase; and

[0083] The third product is subjected to a fourth heat treatment to obtain a binary multiphase alloy including an αMn phase, a γM-Mn phase, and a γ′Mn-M phase.

[0084] In some embodiments, the first heat treatment is a homogenization heat treatment. The homogenization heat treatment can reduce dendritic segregation formed during the casting process, because dendritic segregation causes Mn and metal M to exist in irregular segregation, which is not conducive to obtaining regular pores.

[0085] In some embodiments, the temperature of the first heat treatment is 720°C to 900°C, optionally 850°C to 900°C, for example 900°C), and the treatment time is 12h to 24h, optionally 20h to 24h, for example 24h.

[0086] In some embodiments, the homogenization heat treatment should ensure that the content of Mn-M solid solution in the first product is 95-100 vol%, for example, 96 vol%, 99 vol%, 98 vol%, 99 vol%, or 99.5 vol%, based on the total volume of the first product. The "volume percentage" referred to herein is obtained by calculation through the phase diagram. That is, substantially all of the alloy has been converted into the form of Mn-M solid solution. The first product containing the γMn-M phase has excellent room temperature plasticity. Processed products of different shapes and sizes can be obtained by processing the first product through plastic processing methods such as forging, rolling, and drawing. The processed product can maintain stable shape and size during subsequent heat treatment and dealloying processes.

[0087] In some embodiments, between the first heat treatment and the second heat treatment, the method includes plastically processing (forging, rolling, drawing, etc.) the resulting Mn-M binary alloy into processed products of various shapes and sizes. For example, in some embodiments, the first product is rolled to obtain a foil having a thickness of 0.05 mm to 1 mm, but the present invention is not limited thereto.

[0088] In some embodiments, the second heat treatment is a recrystallization treatment. Recrystallization produces quasi-equiaxed alloy grains. Without recrystallization, the material will develop a rolling orientation along the rolling direction after being rolled into foil. This rolling orientation can result in uneven porosity distribution along the longitudinal direction after corrosion, resulting in strip-shaped corrosion pits or pores parallel to the longitudinal direction.

[0089] In some embodiments, the temperature of the second heat treatment is 720°C to 800°C, optionally 720°C to 750°C, for example 750°C, and the treatment time is 0.5h to 6h, optionally 0.5h to 1h, for example 1h.

[0090] In some embodiments, the third heat treatment is a spinodal decomposition process. Spinodal decomposition decomposes the uniform M-Mn phase to produce a third product comprising a γM-Mn phase and a γ'Mn-M phase. The M-rich γ phase can enhance the strength of the dealloyed rib.

[0091] In some embodiments, the temperature of the third heat treatment is 400°C to 500°C, optionally 400°C to 450°C, for example 450°C; the treatment time is 0.5h to 4h, optionally 1h to 2h, for example 1.5h.

[0092] In some embodiments, the fourth heat treatment is a phase separation treatment. Through the fourth treatment step, an αMn phase is precipitated from the M-rich γ phase and the Mn-rich γ' phase, thereby obtaining a binary multiphase alloy including an αMn phase, a γM-Mn phase, and a γ'Mn-M phase.

[0093] In some embodiments, the temperature of the fourth heat treatment is 600°C to 680°C, optionally 650°C to 680°C, for example 650°C; and the duration of the fourth heat treatment is 1 hour to 6 hours, optionally 4 hours to 6 hours, for example 4 hours. In some embodiments, by adjusting the temperature and duration of the fourth heat treatment, the proportion and size of the precipitated αMn phase can be regulated, thereby regulating the proportion and pore size of pores having the first pore size in the porous material. For example, the lower the fourth heat treatment temperature, the higher the proportion of the αMn phase.

[0094] In some specific embodiments, the method of preparing a Mn-M binary multiphase alloy disclosed herein comprises:

[0095] (1) preparing pure Mn and pure M (purity required to be ≥99.9%) in a weight ratio of (39-78):(22-61), optionally (68-78):(22-32), and preparing a Mn-M binary alloy by vacuum induction melting, wherein the standard electrode potential of the metal M is higher than the standard electrode potential of Mn;

[0096] (2) forging and homogenizing the Mn-M binary alloy obtained in the first step to obtain a first product including a γMn-M solid solution, wherein the forging pressure is 20 tons to 2000 tons, the homogenizing heat treatment temperature is 720° C. to 900° C., and the treatment time is 12 hours to 24 hours;

[0097] (3) rolling the first product to obtain a foil with a thickness of 0.05 mm to 1 mm;

[0098] (4) performing a recrystallization treatment on the foil to obtain a second product, wherein the treatment temperature is 720° C. to 800° C. and the treatment time is 0.5 h to 6 h;

[0099] (5) performing a spinodal decomposition treatment on the second product to obtain a third product, wherein the treatment temperature is 400° C. to 500° C. and the treatment time is 0.5 h to 4 h; and

[0100] (6) The third product is subjected to a phase separation treatment to obtain the Mn-M binary multiphase alloy disclosed herein, with the treatment temperature being 600° C. to 680° C. and the treatment time being 1 h to 6 h.

[0101] Taking Mn-Cu as an example, as shown in the binary alloy phase diagram in Figure 6, the Mn-Cu binary alloy (Mn content 39wt% to 78wt%) is a γ-Mn single-phase structure in the temperature range of 720℃ to 900℃, and an α / γ dual-phase structure in the temperature range of 500℃ to 700℃. Therefore, the Mn-Cu alloy prepared by smelting can be first annealed at a high temperature (700℃ to 865℃) to obtain a γ single-phase alloy with excellent plastic processing ability, and to prepare precursor alloys of different shapes. Subsequently, a low-temperature (600℃ to 680℃) aging treatment is performed to form an α / γ dual-phase structure for the subsequent preparation of the final porous material.

[0102] [Applications of alloys]

[0103] In some embodiments, the present disclosure provides the use of a Mn-M binary multiphase alloy in preparing a porous material. Optionally, the porous material is used as a current collector, catalyst, adsorbent, carrier, molecular sieve, etc.

[0104] [Porous materials]

[0105] In some embodiments, the present disclosure provides a porous material obtained by dealloying the Mn-M binary metal multiphase alloy of the present disclosure, wherein the porous material has pores of a first pore size and a second pore size, the first pore size is n microns, wherein 0.5≤n≤10, optionally 2≤n≤5, and the second pore size is m nanometers, wherein 20<m<200, optionally, 40<m<70.

[0106] In some embodiments, the porous material is gas permeable and / or liquid permeable.

[0107] In some embodiments, the dealloying method is selected from chemical etching, electrochemical etching, or a combination thereof. The dealloying process is mainly based on the difference in standard electrode potential of the precursor components, selectively removing relatively active elements in the system, while the remaining metal atoms are interconnected to obtain a porous material.

[0108] The porous material obtained by the present disclosure has a multi-level pore size distribution characteristic (such as nanopores and micropores). The porous material is particularly suitable for use in anode-free metal batteries (such as anode-free lithium metal batteries or anode-free sodium metal batteries) or metal or alloy anode batteries, but is not limited thereto. For example, the inner wall of a hole with a first pore size (hereinafter referred to as a macropore) can be used as a substrate for the deposition of active substances; in addition, another function of the macropore is to provide an electrolyte infiltration channel. The inner wall of a hole with a second pore size (hereinafter referred to as a small pore) can be used as a substrate for the deposition of active substances. The small pores increase the specific surface area of ​​the material, so that the porous material can load more active substances; in addition, another function of the small pores is to serve as a template for the deposition of active substances. Specifically, due to the limitation of the pore size, the active materials deposited in the pores have nanoscale sizes. Nanoscale active materials have higher ionic conductivity due to their small size, which can improve the overall ionic conductivity of the electrode, thereby improving the rate performance of the battery, and ultimately improving the battery capacity, cycle stability and rate performance as a whole. In addition, another function of the pores is to limit the volume expansion of the active material to avoid its pulverization and failure.

[0109] In addition, the secondary battery and the electric device of the present disclosure will be described below with reference to the drawings as appropriate.

[0110] [Secondary battery]

[0111] In one embodiment of the present disclosure, a secondary battery is provided.

[0112] The term "secondary battery" mentioned herein refers to a battery cell, a battery module, or a battery pack. Each of these is described below.

[0113] Typically, a secondary battery cell consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0114] [Positive electrode]

[0115] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material.

[0116] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0117] In some embodiments, the positive electrode current collector may include the porous material disclosed above. The positive electrode current collector may also be a composite current collector, for example, formed by compounding the porous material disclosed above with a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0118] In some embodiments, when the battery cell is a lithium-ion battery, the positive electrode active material may adopt the positive electrode active material for lithium-ion batteries known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present disclosure is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0119] When the battery cell is a sodium-ion battery, the positive electrode active material may include at least one of a sodium transition metal oxide, a polyanionic compound, and a Prussian blue compound. However, the present disclosure is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for sodium-ion batteries may also be used.

[0120] As an optional technical solution of the present disclosure, in the sodium transition metal oxide, the transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. Sodium transition metal oxide is, for example, Na x MO2, wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, 0 <x≤1。

[0121] As an optional technical solution of the present disclosure, the polyanionic compound can be a compound having sodium ions, transition metal ions and tetrahedral (YO4) n- A class of compounds with anionic units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y can be at least one of P, S and Si; n represents (YO4) n- valence.

[0122] Polyanionic compounds can also be sodium ions, transition metal ions, tetrahedral (YO4) n- A class of compounds containing anion units and halogen anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, and n represents (YO4) n- valence state; the halogen may be at least one of F, Cl and Br.

[0123] Polyanionic compounds can also be sodium ions, tetrahedral (YO4) n- Anion unit, polyhedron unit (ZO y ) m+ and an optional halogen anion. Y can be at least one of P, S and Si, and n represents (YO4) n- Valence state: Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, and m represents (ZO y ) m+ valence state; the halogen may be at least one of F, Cl and Br.

[0124] Polyanionic compounds include NaFePO4, Na3V2(PO4)3, NaM'PO4F (M' is one or more of V, Fe, Mn and Ni) and Na3(VO y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0125] Prussian blue compounds can be compounds containing sodium ions, transition metal ions, and cyanide ions (CN-). The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Prussian blue compounds are, for example, Na a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 <a≤2,0<b<1,0<c<1。

[0126] The battery's charge and discharge processes involve the intercalation and deintercalation of lithium, leading to different molar Li contents at different discharge states. The molar Li contents listed in this disclosure for cathode materials refer to the initial state of the material, i.e., the state before addition. When the cathode material is used in a battery system, the molar Li content will change over the course of charge and discharge cycles.

[0127] In the list of positive electrode materials in this disclosure, the molar content of O is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0128] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0129] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0130] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0131] [Negative electrode current collector and negative electrode sheet]

[0132] The porous material disclosed herein can be directly used as anode-side current collectors (or electrodes) of anode-free metal batteries (eg, anode-free lithium metal batteries or anode-free sodium metal batteries).

[0133] In anode-free lithium batteries, all active lithium ions are initially stored in the positive electrode material. During the initial charge process, lithium ions are extracted from the positive electrode, transferred to the negative electrode, and directly plated in situ on the bare negative electrode current collector, forming a lithium metal anode. Subsequently, during discharge, active lithium ions are stripped from the in situ formed lithium metal anode and embedded in the positive electrode. Lithium anode-free batteries are compact and have a high energy density.

[0134] The porous material disclosed herein can also be used as a negative electrode current collector of a battery containing an active metal / alloy negative electrode.

[0135] In some embodiments, the active metal / alloy is, for example, lithium metal or a lithium alloy.

[0136] In some embodiments, the negative electrode sheet of a lithium metal battery uses the porous material disclosed herein as a negative electrode current collector, and a lithium metal layer is deposited on the outer surface and / or inside the pores of the porous material.

[0137] The term "lithium alloy" as used herein is intended to mean a substance that can form an alloy with lithium by charging and can reversibly adsorb and release lithium. Examples of substances that can form alloys with lithium include elements of metals such as tin (Sn), silicon (Si), zinc (Zn), aluminum (Al), magnesium (Mg), indium (In), cadmium (Cd), lead (Pb), bismuth (Bi) and antimony (Sb), and compounds thereof and alloys thereof (including alloys of lithium with these elemental metals). One or two or more of these substances can be suitably used by appropriate selection.

[0138] In some embodiments, other active metals / alloys besides lithium metal or lithium alloys include elements of metals such as tin (Sn), silicon (Si), zinc (Zn), aluminum (Al), magnesium (Mg), indium (In), cadmium (Cd), lead (Pb), bismuth (Bi), and antimony (Sb), as well as compounds and alloys thereof (including alloys of lithium with these elemental metals).

[0139] In some embodiments, the active metal / alloy can be deposited on the surface and inside the voids of the porous material by methods such as electrodeposition, vapor deposition (such as physical / chemical vapor deposition), and magnetron sputtering to obtain the negative electrode of the battery.

[0140] [Electrolytes]

[0141] The electrolyte conducts ions between the positive and negative electrodes. This disclosure does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. For example, the electrolyte can be liquid, gel, or solid.

[0142] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0143] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0144] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0145] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0146] [Isolation film]

[0147] In some embodiments, the battery cell further includes a separator. The present disclosure has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0148] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0149] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0150] In some embodiments, the battery cell may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0151] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0152] The present disclosure has no particular limitation on the shape of the battery cell, which may be cylindrical, square, or any other shape. For example, FIG7 shows a battery cell 5 with a square structure as an example.

[0153] In some embodiments, referring to Figure 8, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0154] In some embodiments, battery cells may be assembled into a battery module. The battery module may contain one or more battery cells. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0155] Figure 9 shows an example battery module 4. Referring to Figure 9 , within the battery module 4, multiple battery cells 5 may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 5 may be secured together using fasteners.

[0156] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0157] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0158] Figures 10 and 11 illustrate an exemplary battery pack 1. Referring to Figures 10 and 11 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0159] In addition, the present disclosure further provides an electrical device, the electrical device including the secondary battery provided in the present disclosure. The secondary battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0160] As the electrical device, a battery cell, a battery module or a battery pack can be selected according to its usage requirements.

[0161] Figure 12 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0162] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be lightweight and thin, and may use a battery cell as a power source.

[0163] Example

[0164] The following examples are provided. The examples described below are illustrative and are intended only to explain the present disclosure and are not to be construed as limiting the present disclosure. Where specific techniques or conditions are not specified in the examples, the methods were performed according to those described in the literature in the art or according to the product specifications. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0165] Preparation of binary multiphase alloys

[0166] Example 1

[0167] (1) Pure Cu and pure Mn (purity requirement ≥99.9%) are provided in a weight ratio of 39:61, and a Mn-Cu binary alloy is prepared by vacuum induction melting.

[0168] (2) The obtained Mn-Cu alloy was forged and homogenized with heat treatment at a forging pressure of 1000 tons and a homogenization heat treatment temperature of 900°C for 24 hours.

[0169] (3) The Mn-Cu alloy obtained in the second step is rolled to obtain a foil with a thickness of 0.23 mm.

[0170] (4) The Mn-Cu alloy obtained in the third step was recrystallized at 750°C for 1 h.

[0171] (5) The Mn-Cu alloy obtained in the fourth step was subjected to spinodal decomposition treatment at a temperature of 450°C for 2 h.

[0172] (6) The Mn-Cu alloy obtained in the fifth step was subjected to phase separation treatment at a temperature of 600°C for 4 hours.

[0173] Example 2

[0174] (1) Pure Cu and pure Mn (purity requirement ≥99.9%) are provided in a weight ratio of 40:60, and a Mn-Cu binary alloy is prepared by vacuum induction melting.

[0175] (2) The Mn-Cu alloy obtained in the first step was forged and homogenized with a forging pressure of 1000 tons and a homogenization heat treatment temperature of 900°C for 24 hours.

[0176] (3) The Mn-Cu alloy obtained in the second step is rolled to obtain a foil with a thickness of 0.23 mm.

[0177] (4) The Mn-Cu alloy obtained in the third step was recrystallized at 750°C for 1 h.

[0178] (5) The Mn-Cu alloy obtained in the fourth step was subjected to spinodal decomposition treatment at a temperature of 450°C for 2 h.

[0179] (6) The Mn-Cu alloy obtained in the fifth step was subjected to phase separation treatment at a temperature of 650°C for 4 hours.

[0180] Example 3

[0181] (1) Pure Cu and pure Mn (purity requirement ≥99.9%) are provided in a weight ratio of 22:78, and a Mn-Cu binary alloy is prepared by vacuum induction melting.

[0182] (2) The Mn-Cu alloy obtained in the first step was forged and homogenized with a forging pressure of 1000 tons and a homogenization heat treatment temperature of 900°C for 24 hours.

[0183] (3) The Mn-Cu alloy obtained in the second step is rolled to obtain a foil with a thickness of 0.23 mm.

[0184] (4) The Mn-Cu alloy obtained in the third step was recrystallized at 750°C for 1 h.

[0185] (5) The Mn-Cu alloy obtained in the fourth step was subjected to spinodal decomposition treatment at a temperature of 450°C for 2 h.

[0186] (6) The Mn-Cu alloy obtained in the fifth step was subjected to phase separation treatment at a temperature of 650°C for 4 hours.

[0187] Example 4

[0188] (1) Pure Cu and pure Mn (purity requirement ≥99.9%) are provided in a weight ratio of 22:78, and a Mn-Cu binary alloy is prepared by vacuum induction melting.

[0189] (2) The Mn-Cu alloy obtained in the first step was forged and homogenized with a forging pressure of 1000 tons and a homogenization heat treatment temperature of 900°C for 24 hours.

[0190] (3) The Mn-Cu alloy obtained in the second step is rolled to obtain a foil with a thickness of 0.23 mm.

[0191] (4) The Mn-Cu alloy obtained in the third step was recrystallized at 750°C for 1 h.

[0192] (5) The Mn-Cu alloy obtained in the fourth step was subjected to spinodal decomposition treatment at a temperature of 400°C for 2 h.

[0193] (6) The Mn-Cu alloy obtained in the fifth step was subjected to phase separation treatment at a temperature of 650°C for 4 hours.

[0194] Example 5

[0195] (1) Pure Cu and pure Mn (purity requirement ≥99.9%) are provided in a weight ratio of 22:78, and a Mn-Cu binary alloy is prepared by vacuum induction melting.

[0196] (2) The Mn-Cu alloy obtained in the first step was forged and homogenized with a forging pressure of 2000 tons and a homogenization heat treatment temperature of 900°C for 24 hours.

[0197] (3) The Mn-Cu alloy obtained in the second step is rolled to obtain a foil with a thickness of 0.23 mm.

[0198] (4) The Mn-Cu alloy obtained in the third step was recrystallized at 750°C for 1 h.

[0199] (5) The Mn-Cu alloy obtained in the fourth step was subjected to spinodal decomposition treatment at a temperature of 500°C for 2 h.

[0200] (6) The Mn-Cu alloy obtained in the fifth step was subjected to phase separation treatment at a temperature of 650°C for 4 hours.

[0201] Comparative Example 1

[0202] Pure Cu and pure Mn (purity requirement ≥ 99.9%) are provided in a weight ratio of 22:78, and a Mn-Cu binary alloy sample is obtained after vacuum induction melting and forging.

[0203] Comparative Example 2

[0204] The alloy was prepared by the same process as in Example 3, except that pure Cu and pure Mn (purity required to be ≥99.9%) were provided in a weight ratio of 20:80.

[0205] Characterization of alloys

[0206] Morphological characterization

[0207] After each step of the above examples and comparative examples, the obtained products were observed with a metallographic microscope (model NM910-R) and characterized with an X-ray diffractometer (model D8A A25).

[0208] The metallographic images of Examples 1 to 5 and Comparative Example 2 show that, after step 4, quasi-equiaxed crystals were formed, whereas no crystal grains were observed in Comparative Example 1. The following are exemplary metallographic images of the Mn-Cu alloy prepared in Example 3 (see FIG1A ) and a backscattered image (see FIG1B ); and a metallographic image of the alloy prepared in Comparative Example 1 ( FIG4 ).

[0209] The black lines or needles in FIG1A are formed after metallographic corrosion, and the corroded material is the Mn element or a phase with a high Mn content. The continuous groove lines are formed after grain boundary corrosion.

[0210] The gray-black areas in Figure 1B are the grain boundary areas and the Mn-rich areas within the grains. Some areas of the grain boundaries show a discontinuous distribution of Mn (for example, the bright areas on the grain boundaries are where the Mn content is relatively low).

[0211] According to FIG. 4 , it can be seen that, in the case of no heat treatment, the rolling morphology in the rolling direction (horizontal direction) is retained, and the grain boundaries are completely destroyed.

[0212] Characterization of grain size

[0213] The alloys prepared in Examples 1 to 5 and Comparative Example 2 were polished using 200-, 600-, 800-, and 1200-mesh sandpaper and diamond polishing paste until the metal surface exhibited a mirror finish. The samples were then etched with ferric chloride for 10 seconds. After cleaning and drying with alcohol and deionized water, the samples were placed under a metallographic microscope to obtain their metallographic structures. The sizes of 50 grains were counted, and the average value was calculated as the grain size of the sample. The results are shown in Table 1 below.

[0214] HV hardness

[0215] The test equipment was an HVS-1000 hardness tester, and the load force was 300 g. The results are shown in Table 1 below.

[0216] Crystal phase

[0217] The test equipment was an X-ray diffractometer (model D8A A25), with a scanning angle of 30-110° and a scanning step size of 0.016°. The XRD pattern of the Mn-Cu alloy prepared in Example 3 is shown here as an example (see Figure 2). Figure 2 shows diffraction peaks of the αMn phase, the γ'Mn-Cu phase, and the γCu-Mn phase.

[0218] Preparation of porous materials

[0219] The alloys obtained in Examples 1 to 5 and Comparative Examples 1 to 2 were cut into samples with a size of 2 cm×3 cm and placed in a 0.1 mol / L hydrochloric acid etching solution for free chemical etching. When no bubbles emerged, the dealloying process was completed.

[0220] The continuity of the skeleton after dealloying was then observed using a scanning electron microscope (Zeiss Gemini 360). The results are shown in Table 1. FIG3A shows a scanning electron microscope photograph of the Mn-Cu alloy of Example 3 after dealloying, and FIG3B shows an enlarged view (surface scan) of the ridge diameter microregion of FIG3A. FIG5 shows a scanning electron microscope photograph of the alloy of Comparative Example 1 after dealloying.

[0221] Table 1

[0222] As shown in the scanning electron microscope photograph of Figure 3A, the porous copper has pores with a first pore size (hereinafter referred to as macropores) and pores with a second pore size (hereinafter referred to as small pores). 100 macropores and 100 small pores were selected from the scanning electron microscope photograph, and the pore sizes of the macropores and small pores were measured respectively, and the average values ​​were calculated respectively. The results showed that the average pore size of the macropores of the obtained porous copper was 6.4 microns, and the average pore size of the small pores was 86 nanometers. Similar results were obtained in the alloys prepared in other embodiments. It can be seen from the above experimental data that the porous material of the present invention can be successfully prepared by the binary alloy disclosed in the present invention.

[0223] In contrast, as clearly shown in the photographs in Figure 5, the alloy of Comparative Example 1 failed to form a continuous skeleton after corrosion, and therefore failed to produce a porous material with regular pores. Furthermore, the alloy of Comparative Example 2 was directly pulverized after corrosion, and no corresponding SEM photographs were obtained.

[0224] It should be noted that the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present disclosure, embodiments having substantially the same structure as the technical concept and exerting the same effects are all included in the technical scope of the present disclosure. In addition, within the scope of the present disclosure, various modifications that can be imagined by those skilled in the art to the embodiments, and other methods constructed by combining some of the constituent elements of the embodiments are also included in the scope of the present disclosure.

Claims

1. A Mn-M binary multiphase alloy, comprising: 39wt%≤Mn≤78wt%, the rest includes metal M; wherein the standard electrode potential of the metal M is higher than the standard electrode potential of Mn, and The binary metal multiphase alloy contains αMn phase, γM-Mn phase and γ'Mn-M phase.

2. The multiphase alloy according to claim 1, wherein The multi-phase alloy includes 68 wt %≤Mn≤78 wt %.

3. The multiphase alloy according to claim 1 or 2, wherein: The metal M is selected from one of Cu, Cr, Co, Sn and Ni.

4. The multiphase alloy according to any one of claims 1 to 3, wherein The multiphase alloy includes quasi-equiaxed grains.

5. The multiphase alloy according to claim 4, wherein The quasi-equiaxed grains have an average size of 5 μm to 30 μm.

6. The multiphase alloy according to claim 5, wherein The quasi-equiaxed grains have an average size of 10 μm to 25 μm.

7. The multiphase alloy according to any one of claims 1 to 6, wherein The grains of the multi-phase alloy have grain boundaries where metal Mn and metal M are discontinuously distributed.

8. The multiphase alloy according to any one of claims 1 to 7, wherein The αMn phase accounts for 4.6 wt% to 65.6 wt% of the multi-phase alloy.

9. The multiphase alloy according to claim 8, wherein The content of Mn element in the αMn phase is greater than 99 wt %.

10. The multiphase alloy according to any one of claims 1 to 9, wherein The γM-Mn phase and the γ′Mn-M phase together account for 34.4 wt % to 95.3 wt % of the multi-phase alloy.

11. The multiphase alloy according to claim 10, wherein: The content of M element in the γM-Mn phase is 35 wt% to 100 wt%, and the content of Mn element in the γ′Mn-M phase is 60 wt% to 72 wt%.

12. A method for preparing a Mn-M binary multiphase alloy, comprising: Smelting Mn and metal M in a weight ratio of (39-78):(22-61) to obtain a Mn-M binary alloy, wherein the standard electrode potential of the metal M is higher than the standard electrode potential of Mn; performing a first heat treatment on the obtained Mn-M binary alloy to obtain a first product including a γMn-M solid solution; performing a second heat treatment on the first product to crystallize the first product to obtain a second product; performing a third heat treatment on the second product to obtain a third product including a γM-Mn phase and a γ'Mn-M phase; and The third product is subjected to a fourth heat treatment to obtain a binary multiphase alloy including an αMn phase, a γM-Mn phase, and a γ′Mn-M phase.

13. The method according to claim 12, wherein: The method may include one or more of the following features: The first heat treatment is a homogenization heat treatment; The temperature of the first heat treatment is 720°C to 900°C; The first heat treatment time is 12h to 24h; The alloy is subjected to plastic working after the first heat treatment.

14. The method according to claim 12 or 13, wherein: The method may include one or more of the following features: The second heat treatment is a recrystallization treatment; The temperature of the second heat treatment is 720°C to 800°C; The second heat treatment time is 0.5h to 6h.

15. The method according to any one of claims 12 to 14, wherein The method may include one or more of the following features: The third heat treatment is a spinodal decomposition treatment; The temperature of the third heat treatment is 400°C to 500°C; The third heat treatment lasts for 0.5 h to 4 h.

16. The method according to any one of claims 12 to 15, wherein The method may include one or more of the following features: The fourth heat treatment is a phase separation treatment; The temperature of the fourth heat treatment is 600°C to 680°C; The fourth heat treatment lasts for 1 hour to 6 hours.

17. Use of the Mn-M binary multiphase alloy according to any one of claims 1 to 11 or the Mn-M binary multiphase alloy prepared by the method according to any one of claims 12 to 16 in preparing a porous material, wherein optionally, the porous material is used as a current collector.

18. A porous material, obtained by dealloying the Mn-M binary multiphase alloy according to any one of claims 1 to 11 or the Mn-M binary multiphase alloy prepared by the method according to any one of claims 12 to 16, wherein the porous material has pores of a first pore size and a second pore size, the first pore size is n micrometers, where 0.5≤n≤10, and the second pore size is m nanometers, where 20<m<200.

19. The porous material according to claim 18, wherein 2≤n≤5。 20. The porous material according to claim 18 or 19, wherein 40＜m＜70。 21. A current collector comprising the porous material according to any one of claims 18 to 20.

22. A secondary battery comprising the current collector according to claim 21.

23. An electric device comprising the secondary battery according to claim 22.

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