CN107123811B

CN107123811B - Dual-scale porous copper-aluminum-manganese shape memory alloy composite material and preparation method and application thereof

Info

Publication number: CN107123811B
Application number: CN201710232382.4A
Authority: CN
Inventors: 袁斌; 罗政; 黎花; 梁杰铬; 高岩; 朱敏
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2017-04-11
Filing date: 2017-04-11
Publication date: 2020-01-10
Anticipated expiration: 2037-04-11
Also published as: CN107123811A

Abstract

The invention discloses a dual-scale porous copper-aluminum-manganese shape memory alloy composite material and a preparation method and application thereof. The preparation method comprises the steps of proportioning a pure Cu block, a pure Al block and a pure Mn block, and obtaining a copper-aluminum-manganese alloy ingot through induction melting; heating and melting the obtained copper-aluminum-manganese alloy cast ingot, and preparing a mixture of the copper-aluminum-manganese alloy and the spherical silica gel by using the spherical silica gel as a pore forming agent and using high-purity argon as pressure; then, carrying out austenitizing and hydrofluoric acid solution filtration treatment on the mixture to prepare a three-dimensional super-elastic porous copper-aluminum-manganese memory alloy with the pore size of 0.71-1 mm; and finally, carrying out dealloying treatment on the hyperelastic porous copper-aluminum-manganese memory alloy by adopting a chloride ion-containing solution to obtain the dual-scale porous Cu/beta-CuAlMn composite material. The preparation method provided by the invention has strong controllability, can be used for preparing the electrode material of the lithium ion secondary battery, and obviously improves the cycle stability of the electrode material.

Description

Dual-scale porous copper-aluminum-manganese shape memory alloy composite material and preparation method and application thereof

Technical Field

The invention relates to a preparation method and application of a dual-scale porous copper-aluminum-manganese shape memory alloy composite material, belonging to the fields of porous functional metal materials and lithium ion secondary batteries.

Background

Lithium ion secondary batteries have been widely used in various mobile portable devices since their first commercial use in the 90 s of the 20 th century because of their high operating voltage, high energy density and long cycle life. Currently, various countries in the world are striving to develop existing lithium ion secondary battery technologies and continue to expand their application fields, such as electric vehicles, medical treatment, and national defense. However, lithium ion batteries are increasingly unable to meet the requirements for high capacity and long life of mobile devices. Therefore, the development of high-capacity lithium ion secondary batteries is one of the most feasible solutions in the current battery field.

The performance indexes such as capacity and cycle life of a lithium ion secondary battery are mainly determined by electrode materials (positive electrode and negative electrode materials) thereof. The currently known types of positive electrode materials are mainly metal salts of lithium, such as LiCoO₂、Li₂MnO₄、LiFePO₄And the like, the main development direction is towards high voltage and high safety, and the improvement of the specific capacity is relatively limited. More attention has been directed to the development of a new generation of high capacity anode materials. The negative electrode material commercially used at present is graphite, and the graphite has better cycling stability because the lithium intercalation process is that lithium ions are intercalated into graphite sheets and the volume expansion of the whole process is smaller (12%). However, its theoretical capacity is low, only 372mAh/g, and the capacity of the graphite negative electrode commercialized at present has been close to its theoretical capacity. However, the new high capacity anode materials are mainly metal based anode materials, such as Sn, Si, SnO₂、Fe₂O₃And the theoretical capacity is more than 3 times of that of graphite. For example, Sn cathode materials not only have high theoretical capacity (994mAh/g), but also have good conductivity and a moderate voltage platform, and are one of the research hotspots of the current lithium ion battery cathode materials. However, the lithium insertion process of Sn is the alloying of Sn and Li to form Li_xThe process of Sn intermetallic compounds causes huge volume expansion (about 260%) to cause pulverization and cracking of Sn, thereby losing good contact with the current collector, increasing internal resistance, causing a sharp drop in reversible capacity, and deterioration in cycle stability. Therefore, the huge volume expansion during the charge-discharge cycle is the main reason for the poor cycle stability of the Sn negative electrode material, and is also a key common problem faced by all metal-based negative electrode materials. At present, methods for improving the cycling stability of metal-based negative electrode materials such as Sn mainly comprise a nanocrystallization method, a multiphase compounding method and a method for constructing a three-dimensional porous current collector.

The nano-crystallization is to reduce the size of Sn particles to nano-scale, and can reduce the absolute volume expansion of the Sn particles, thereby reducing the pulverization and cracking of the Sn particles and improving the cycle performance to a certain extent. However, nano-scale Sn particles are prone to agglomeration after many cycles, resulting in a dramatic drop in capacity. Multiphase compounding refers to a method of compounding Sn particles with a second phase, active or inactive. The composite second phase serves to mitigate the volume expansion of Sn. However, the conventional second phase has a limited capacity to relieve volume expansion of Sn, and cracks may occur after many cycles, resulting in capacity fading. Thus, researchers have proposed using shape memory alloys as the second phase to mitigate Sn volume expansion. Due to the stress-induced martensitic transformation characteristic of the shape memory alloy, large strain (maximum 18%) changes can be relieved many times through the transformation, thereby showing good cycle life. However, the memory alloy itself as the second phase does not have Li insertion ability, and the use of a large amount of memory alloy as the buffer matrix causes a low capacity of the entire negative electrode material. The third method is to replace the common copper foil current collector with a three-dimensional porous current collector, and to utilize the pores to relieve the huge volume expansion of Sn. At present, researchers load Sn by using micron-scale copper foam, micron-scale nickel foam and nanometer-scale porous copper as current collectors, and find that the Sn not only can improve the overall capacity, but also has better cycle performance. However, the Cu or Ni matrix still undergoes plastic deformation after undergoing large strain, the stress generated by volume expansion of Sn cannot be completely relieved by using single porous Cu or Ni as a pore framework, and the matrix framework still cracks and even collapses after multiple cycles, so that the capacity is rapidly reduced. Moreover, the single micron-scale pores can not well prevent the Sn and other negative electrode materials from falling off from the pores, and the single nanometer-scale pores do not have enough pores to relieve the volume expansion.

In summary, the current methods alone cannot solve the contradiction between the cycling stability and the overall specific capacity of the novel high-capacity negative electrode material, so that the methods must be effectively combined to eliminate the extreme stress of the novel negative electrode material in the lithium intercalation process and improve the load rate of the unit active phase.

The chinese patent application CN 105441708A discloses a method for preparing porous copper-based shape memory alloy by using silica gel as pore-forming agent. The method comprises the steps of firstly, proportioning a pure Cu block, a pure Al block and a pure Mn block, and smelting to obtain a copper-aluminum-manganese alloy ingot; the pore-forming agent adopts silica gel particles which are subjected to heat treatment to expand and dehydrate the silica gel particles, and then the particles with the diameter of 2.2-2.6 mm are screened out. Then sequentially putting the screened silica gel particles, the ceramic sieve mesh thin plate and the alloy cast ingot into an alumina crucible; and then, putting the loaded alumina crucible into a vertical tubular furnace for heating, introducing high-purity argon gas with certain pressure after the alloy ingot is completely melted, so that the molten metal liquid completely permeates into gaps of the pore-forming agent, and then cooling to room temperature along with the furnace to prepare the mixture of the copper-aluminum-manganese alloy and the silica gel particles. And finally, dissolving and filtering the silica gel particles by using hydrofluoric acid water solution with certain concentration to prepare the porous copper-aluminum-manganese alloy with the aperture size of 2.2-2.6 mm. However, the pores of the porous memory alloy prepared by the method are 2.2-2.6 mm, on one hand, the large pores have smaller specific surface area and cannot be loaded with more active substances; on the other hand, the larger pores cannot limit the Sn particles from falling off the current collector, and still increase the internal resistance, resulting in an increase in irreversible capacity and a rapid decrease in cycle performance. Therefore, the present invention cannot be applied to a lithium ion secondary battery as an electrode material collector.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention improves and optimizes the preparation method of the porous copper-aluminum-manganese shape memory alloy on the basis of the invention CN 105441708A, and aims to provide a dual-scale porous copper-aluminum-manganese shape memory alloy composite material which has strong controllability, small pores, high porosity and a three-dimensional communicated pore structure and a preparation method thereof.

The invention also aims to provide the application of the dual-scale porous copper-aluminum-manganese shape memory alloy composite material in a secondary battery electrode material, so that the cycling stability of the electrode material is obviously improved.

According to the invention, a micron-sized porous copper-aluminum-manganese memory alloy precursor is prepared, nano-scale pores are obtained on the surface of the micron-sized pores through further dealloying treatment, and the dual-scale porous copper-aluminum-manganese shape memory alloy composite material is finally prepared, the size of the nano-scale pores and the thickness of the porous layer can be well regulated and controlled, the material is used as a current collector to relieve the volume change of a high-capacity negative electrode material in the charging and discharging process, and the purposes of improving the capacity and the cycle performance of a lithium ion battery can be effectively achieved.

The porous copper aluminum manganese shape memory alloy is further corroded through dealloying, a layer of nano porous copper layer is formed on the surface, and the dual-scale porous copper aluminum manganese shape memory alloy composite material is prepared. The composite material is used as a current collector, and after the high-capacity negative electrode material is filled, the nano pores can accommodate a part of active negative electrode material, and simultaneously limit the growth and falling of the active particles, so that the active particles are kept in good contact with the current collector, and no additional conductive agent is needed; the micropores can load a part of active negative electrode materials, meanwhile, a part of micropores and the superelasticity of the copper-aluminum-manganese memory alloy matrix can accommodate huge volume expansion, and the micropores can also provide a quick channel for the diffusion of lithium ions, so that the multiplying power performance of the lithium ion battery is improved; the prepared dual-scale porous copper-aluminum-manganese memory alloy composite material has good ductility, electric conduction and heat conduction characteristics, can better meet the requirements of serving as a current collector, and is low in price and convenient to process.

The invention can be realized by the following technical scheme:

the preparation method of the dual-scale porous copper-aluminum-manganese shape memory alloy composite material comprises the following steps:

(1) preparing CuAlMn alloy cast ingots by carrying out induction melting on pure Cu, pure Al and pure Mn raw materials; the mass ratio of Cu to Al to Mn in the CuAlMn alloy ingot is (100-X-Y): x: y, wherein X is 8-11, and Y is 9-12;

(2) dehydrating the original silica gel particles in a muffle furnace at a low temperature, then performing modification treatment, and cooling the original silica gel particles to room temperature along with the furnace; after complete cooling, screening out spherical silica gel pore-forming agent with the diameter of 0.71-1 mm;

(3) spherical silica gel pore-forming agent obtained in the step (2), round ceramic sieve pore sheet and copper aluminum manganese obtained in the step (1)Sequentially putting alloy ingots into a crucible; placing the loaded crucible into the inner cavity of a vertical tube furnace, vacuumizing the tube furnace to 8 x 10^- ³Heating to 1090-1110 ℃ below Pa, preserving heat for 15-30 min, then closing the vacuum pump, introducing high-purity argon, keeping the pressure in the furnace chamber at 0.1-0.3 MPa, continuing preserving heat at the temperature for 3-5 min, and then cooling the pressure maintaining furnace to room temperature to obtain a mixture of copper-aluminum-manganese alloy and spherical silica gel;

(4) putting the mixture of the copper-aluminum-manganese alloy and the spherical silica gel prepared in the step (3) into a muffle furnace for austenitizing treatment to obtain a mixture of the fully-austenitic copper-aluminum-manganese alloy and the spherical silica gel;

(5) immersing the mixture of the fully austenitic copper-aluminum-manganese alloy and the spherical silica gel obtained in the step (4) into a 10-25 mass percent HF acid aqueous solution for leaching, performing leaching under the condition of 30-50 ℃ with the assistance of ultrasonic vibration, replacing the solution every 3-6 hours, taking out the porous metal after the pore-forming agent is fully leached, cleaning with clear water with the assistance of ultrasonic vibration, and drying to obtain the super-elastic micron porous copper-aluminum-manganese alloy;

(6) and (3) immersing the super-elastic micro-porous copper-aluminum-manganese alloy prepared in the step (5) into a solution containing chloride ions for dealloying, then washing and drying the dealloyed material, and preparing the double-scale porous copper-aluminum-manganese shape memory alloy composite material.

To further achieve the object of the present invention, it is preferable that the purity of the pure Cu, pure Al and pure Mn raw materials of step (1) is 99% or more in mass percentage.

Preferably, the particle size of the original silica gel in the step (2) is 0.45-0.71 mm; the silica gel dehydration treatment temperature is 150-220 ℃, and the heat preservation time is 0.5-1 h.

Preferably, the modification treatment temperature in the step (2) is 950-1000 ℃, and the heat preservation time is 1-2 h.

Preferably, the diameter of the ceramic mesh sheet in the step (3) is 0.5-1 mm smaller than that of the alumina crucible, the aperture of the mesh is 1-2 mm, the thickness of the mesh is 1-2 mm, and the ceramic mesh sheet is used for supporting the CuAlMn alloy ingot to separate the CuAlMn alloy ingot from the pore-forming agent, and does not hinder the liquid metal from flowing and permeating during later pressurizing; the material does not react with molten metal and is high temperature resistant ceramic or graphite.

Preferably, the austenitizing treatment in the step (4) is carried out by keeping the temperature at 850-950 ℃ for 0.5-3 h, and then cooling, wherein the cooling mode is quenching in ice water for cooling.

Preferably, the drying in the step (5) is drying in a drying oven at 60-100 ℃ for 6-8 h.

Preferably, the solution containing chloride ions in the step (6) is an aqueous solution or an organic solution, and the concentration of the chloride ions is 0.1-20 wt.%; the dealloying time in the step (6) is 0.5-3 h, and the dealloying temperature is 0-90 ℃; washing in the step (6) is washing by deionized water and ultrasonic vibration; the drying in the step (6) is to place the mixture into a vacuum drying oven for drying, wherein the vacuum degree is 6 multiplied by 10^-3Pa below, the temperature is 80-100 ℃, and the time is 6-12 h.

The dual-scale porous copper-aluminum-manganese shape memory alloy composite material is prepared by the preparation method.

The dual-scale porous copper-aluminum-manganese shape memory alloy composite material is applied to a secondary battery electrode material.

The principle of the invention is that the austenitized micron porous copper-aluminum-manganese alloy is in a single beta phase at room temperature and has super elasticity. While the corrosion potential of Al and Mn elements in the β phase is lower than that of Cu. Therefore, in a solution containing chloride ions, Al and Mn atoms are preferentially corroded, and the rest Cu is gradually gathered and diffused to form a three-dimensional nano porous structure. Because dealloying is a process from the outside to the inside, the thickness of the nano porous layer and the pore diameter of the nano pores can be regulated and controlled by controlling the concentration of chloride ions, dealloying temperature and time, and the dual-scale porous copper-aluminum-manganese shape memory alloy composite material is finally prepared.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the dual-scale porous copper-aluminum-manganese shape memory alloy composite material prepared by the invention has smaller pores (micron pore diameter)About 0.71-1 mm, nano-pore diameter of about 50-300 nm), higher porosity (more than 75-93%) and specific surface area (about 2.8-3.1 m)²/g)。

(2) The dual-scale porous copper-aluminum-manganese shape memory alloy composite material current collector prepared by the invention has a unique three-dimensional communicated pore structure: the micron pores can provide channels for diffusion of lithium ions, facilitate uniform distribution of electrolyte, and relieve volume expansion of the metal-based negative electrode material in the charging and discharging processes through the pores; the nano pores can not only limit the growth of particles of the metal-based negative electrode material, but also enable active substances to be in good contact with a three-dimensional conductive current collector, thereby saving the addition of a conductive agent. Meanwhile, the three-dimensional porous beta-phase matrix has superelasticity, and can further relieve stress generated by volume expansion of the metal-based negative electrode material, so that the huge volume expansion of the high-capacity metal-based negative electrode material can be relieved more effectively, and the overall capacity and cycle life of the lithium ion battery can be improved.

(3) The components, the pore size and the porosity of the dual-scale porous copper-aluminum-manganese shape memory alloy composite material prepared by the method can be regulated and controlled by regulating and controlling the size of the pore-forming agent, the concentration of the corrosive liquid, the corrosion time and the corrosion temperature, and the method is simple and controllable and can be used for batch production.

Drawings

FIG. 1 is a photomicrograph of a three-dimensional porous copper aluminum manganese shape memory alloy substrate of example 1;

FIG. 2 is a metallographic photograph of a three-dimensional porous Cu-Al-Mn shape memory alloy matrix according to example 1;

FIG. 3 is an XRD diffractogram of the three-dimensional porous Cu-Al-Mn shape memory alloy substrate of example 1;

FIG. 4 is a DSC curve of the three-dimensional porous Cu-Al-Mn shape memory alloy substrate of example 1;

FIG. 5 is a superelastic curve at room temperature for the three-dimensional porous Cu-Al-Mn shape memory alloy substrate of example 1;

FIG. 6 is an XRD diffractogram of the three-dimensional porous Cu-Al-Mn shape memory alloy matrix in example 1 after 30min dealloying;

FIG. 7 is an SEM image of the surface of the three-dimensional porous Cu-Al-Mn shape memory alloy matrix of example 1 after 30min dealloying;

FIG. 8 is an XRD diffraction pattern of the three-dimensional porous Cu-Al-Mn shape memory alloy matrix of example 1 after 30min tin plating;

FIG. 9 is an SEM image of the surface of the three-dimensional porous Cu-Al-Mn shape memory alloy substrate of example 1 after 30min tin plating;

FIG. 10 is a discharge cycle performance curve of the three-dimensional porous Cu-Al-Mn shape memory alloy substrate of example 1 after 30min tin plating;

FIG. 11 is an XRD diffractogram of the three-dimensional porous Cu-Al-Mn shape memory alloy substrate of example 2 after de-alloying for 60 min;

FIG. 12 is a surface SEM image of the three-dimensional porous Cu-Al-Mn shape memory alloy matrix of example 2 after dealloying for 60 min;

FIG. 13 is an XRD diffractogram of the three-dimensional porous Cu-Al-Mn shape memory alloy matrix of example 3 dealloyed for 90 min;

FIG. 14 is a surface SEM image of the three-dimensional porous Cu-Al-Mn shape memory alloy matrix of example 3 after dealloying for 90 min.

Detailed Description

For a better understanding of the present invention, the present invention will be further described with reference to the following examples and drawings, but the present invention is not limited thereto.

Example 1

(1) Weighing the pure copper blocks, the pure aluminum blocks and the pure manganese blocks according to the mass percentage of 80:9:11, and then obtaining the copper-aluminum-manganese alloy cast ingot through induction melting.

(2) Screening original silica gel particles with the diameter of 0.45-0.71 mm, putting the particles into a muffle furnace, preserving heat for 0.5h at 200 ℃ for dehydration treatment, and preserving heat for 2h at 980 ℃ for modification treatment, so that the particles expand and lose the water absorption effect. And screening out spherical silica gel pore-forming agent with the diameter of 0.71-1 mm after the material is cooled along with the furnace.

(3) Keeping an alumina crucible vertical, and sequentially putting the spherical silica gel pore-forming agent obtained in the step (2), a round ceramic sieve pore sheet (the thickness is 2mm, and the aperture of a sieve pore is 1mm) and the alloy cast ingot obtained in the step (1). Will be loaded wellThe crucible is put into a vertical tubular furnace; the tube furnace is evacuated to 8X 10^-3And (4) heating to 1100 ℃ below Pa, preserving heat for 15min, closing the vacuum pump after the alloy is completely melted, adding high-purity argon to 0.1MPa, and preserving heat for 5min to ensure that the molten metal completely permeates into gaps of the pore-forming agent. Then, maintaining the pressure, cooling to room temperature along with the furnace, and obtaining the mixture of the copper-aluminum-manganese alloy and the spherical silica gel

(4) Putting the mixture of the copper-aluminum-manganese alloy prepared in the step (3) and the spherical silica gel into a muffle furnace for austenitizing treatment; the austenitizing temperature is 850 ℃, the heat preservation time is 2 hours, and then the mixture is quenched into ice water for cooling to obtain the mixture of the complete austenite copper-aluminum-manganese alloy and the spherical silica gel.

(5) And (4) immersing the mixture of the completely austenitic copper-aluminum-manganese alloy and the spherical silica gel in the step (4) into a hydrofluoric acid aqueous solution with the mass fraction of 25% for leaching. And (3) carrying out dissolution filtration at 30 ℃ by assisting ultrasonic vibration, replacing the solution every 4 hours, taking out the porous metal after the pore-forming agent is completely dissolved and filtered, cleaning the porous metal by using clear water by assisting ultrasonic vibration, and then drying the porous metal in a drying oven at the temperature of 60 ℃ for 8 hours to obtain the super-elastic micron porous copper-aluminum-manganese alloy, which is shown in figure 1. As can be seen from the figure, the spherical pore size of the micron porous copper-aluminum-manganese shape memory alloy matrix finally prepared by the method is 0.7-1 mm, while the pore size prepared in the Chinese patent CN 105441708A is 2.2-2.6 mm, so that the micron porous copper-aluminum-manganese shape memory alloy matrix is smaller in pore size and larger in specific surface area, and can load more negative electrode materials; the structure of the sample after austenitizing under a metallographic microscope is a parent phase (as shown in fig. 2), the grain size is 300-400 μm, and a bamboo-joint crystal structure is presented (namely, no three grain boundary intersection regions exist). The XRD diffraction pattern (as shown in figure 3) further proves that the austenitized porous copper-aluminum-manganese memory alloy matrix is a single austenite beta phase, and the diffraction peak shows the characteristic of preferred orientation. The DSC result (figure 4) shows that the porous copper-aluminum-manganese shape memory alloy matrix after austenitizing shows a unique phase transformation process, the martensite transformation starting temperature is-50 ℃, the martensite reverse transformation finishing temperature is-20 ℃, and the obtained three-dimensional porous copper-aluminum-manganese shape memory alloy matrix is a complete parent phase at room temperature. And cutting the porous copper-aluminum-manganese shape memory alloy matrix subjected to complete austenitizing into a cylindrical block with the diameter of 10mm and the height of 15mm, and then performing a cyclic compressive stress strain test. The test was carried out on an Instron5984 apparatus, USA, at ambient temperature and at a compressive strain rate of 0.2 mm/s. As shown in fig. 5, under the condition of strain of 1% and 2%, the porous copper aluminum manganese memory alloy matrix can completely recover at room temperature; when the strain condition is 3%, the recovery strain is 2.71%, and the recovery rate is as high as 90.3%, which indicates that the porous copper-aluminum-manganese shape memory alloy matrix has good superelasticity at room temperature, can effectively relieve the stress generated by tin in the lithium embedding process, and can keep the integrity of the porous frame in the process of multiple charge-discharge cycles.

(6) Cutting the super-elastic micro-porous copper-aluminum-manganese alloy wire obtained in the step (5) into blocks of 8 multiplied by 1mm, cleaning oil stains, immersing the blocks into a hydrochloric acid aqueous solution with the mass fraction of 20% for dealloying, wherein the dealloying temperature is 80 ℃, and the dealloying time is 30 min. Then, the de-alloyed sample is cleaned by deionized water and ultrasonic vibration, and then is put into a vacuum drying oven for drying, wherein the vacuum degree is 6 multiplied by 10^-3And (3) the temperature is 100 ℃ below Pa, and the time is 6 hours, so that the dual-scale porous copper-aluminum-manganese composite current collector is prepared. The XRD diffractogram (figure 6) shows that the sample composition phase after 30min of dealloying is a composite phase of pure copper and beta phase. Observing the surface morphology of the micron pores, and as shown in fig. 7, finding that a layer of nano porous structure is generated on the surface of the original micron pores after alloying for 30min, wherein the size of the pores is 50-100 nm, and preparing the dual-scale porous copper-aluminum-manganese shape memory alloy composite material. The specific surface area of the sample before and after dealloying is measured by adopting BET, the test is firstly carried out by carrying out degassing treatment on the sample after heat preservation for 2 hours at the temperature of 200 ℃, and then an adsorption experiment is carried out after liquid nitrogen is used as a coolant for cooling, and the specific surface area result can be directly obtained from instrument measurement data. The test result shows that the specific surface area of the super-elastic micro-porous copper-aluminum-manganese alloy matrix is 1.409m²Per gram, and the specific surface area of the dealloyed dual-scale porous copper-aluminum-manganese alloy is as high as 2.801m²The specific surface area is doubled. At the same time, toThe porosity of the prepared dual-scale porous copper-aluminum-manganese composite material is up to 93% after 30min of alloying, while the porosity of the prepared micron porous copper-aluminum-manganese composite material in the Chinese invention patent is only 78%, and the increase of the porosity means the increase of the specific surface area and can load more active substances, thereby integrally increasing the capacity of the lithium ion secondary battery.

Immersing the dual-scale porous copper-aluminum-manganese composite material current collector prepared in the step (6) into a chemical tin plating solution at room temperature, wherein the tin plating solution comprises the following components: 2.5mol/L NaOH, 0.4mol/L SnSO₄、0.7mol/L NaH₂PO₄、0.6mol/LNa₃C₆H₅O₇. The chemical tinning time is 3 minutes, and finally the dual-scale porous copper-aluminum-manganese/Sn composite negative electrode material is prepared; and cleaning the composite material after tinning with deionized water, and then putting the composite material into a vacuum drying oven for drying for 8 hours. The XRD diffractogram of the obtained composite anode material (fig. 8) showed that after electroless tin plating, diffraction peaks (characteristic peaks of 30.6 °, 32.0 ° and 44.9 °) of tin appeared. As can be seen from its surface topography after tin plating (fig. 9), part of the small pores are filled with nano-sized tin particles, but the porous structure remains and can serve as a channel for lithium ion diffusion.

And pressing the prepared composite negative electrode material serving as a positive electrode, PE serving as a diaphragm, a metal lithium sheet serving as a negative electrode and ethylene carbonate serving as electrolyte into a button cell with the diameter of 12mm in a glove box to form a half cell. The prepared half cell is subjected to charge and discharge performance test in a blue cell test system, the cycle discharge performance curve is shown in fig. 10, the result is measured in the blue (LAND) cell test system, and the specific parameters are as follows: the current density is 0.5mA/cm²The charge and discharge voltage range is 0.01V-2V. As can be seen from the graph, the first discharge capacity reached 3.675mAh/cm²The first coulombic efficiency is 75.6%, the reversible capacity after one circulation is 74.7% of the original capacity, and the capacity is still maintained at 1.31mAh/cm after 100 circulations²And was 35.6% of the initial capacity. The sample disclosed in patent CN 105441708A cannot be loaded with Sn at all, nor assembled into a composite electrode material; to use businessThe copper foil is used as a current collector, and the first discharge capacity of the negative electrode material assembled after Sn plating is only 0.37mAh/cm²The first coulombic efficiency was only 27%, the capacity after one cycle was 27.9% of the original capacity, and the capacity fade after 100 cycles was 13.3% of the original capacity, which are far worse than the samples prepared in this example. Therefore, the capacity and the cycle performance of the lithium ion secondary battery can be remarkably improved by using the dual-scale porous copper-aluminum-manganese composite material as the current collector.

Example 2

(1) Weighing the pure copper blocks, the pure aluminum blocks and the pure manganese blocks according to the mass percentage of 81:9:12, and then obtaining the copper-aluminum-manganese alloy cast ingot through induction melting.

(2) Screening out original silica gel with the diameter of 0.45-0.71 mm, putting the silica gel into a muffle furnace, preserving heat for 1h at 160 ℃ for dehydration, and then preserving heat for 1.5h at 1000 ℃ for modification treatment, so that the silica gel expands and loses the water absorption effect. And screening out spherical silica gel pore-forming agent with the diameter of 0.71-1 mm after the material is cooled along with the furnace.

(3) Keeping an alumina crucible vertical, sequentially putting the spherical silica gel pore-forming agent obtained in the step (2), a circular ceramic sieve pore sheet (the thickness is 2mm, and the aperture of a sieve pore is 1.5mm) and the copper-aluminum-manganese alloy cast ingot obtained in the step (1), and putting the loaded crucible into a vertical tubular furnace; the tube furnace is evacuated to 8X 10^-3Heating to 1110 ℃ below Pa, keeping the temperature for 15min, after the alloy is completely melted, closing a vacuum pump, adding high-purity argon to 0.2MPa, keeping the temperature for 3min to ensure that the melted metal completely permeates into pores of the pore-forming agent, then keeping the pressure, cooling to room temperature along with the furnace to obtain a mixture of the copper-aluminum-manganese alloy and the spherical silica gel

(4) And (4) putting the mixture of the copper-aluminum-manganese alloy and the spherical silica gel prepared in the step (3) into a muffle furnace for austenitizing treatment, wherein the austenitizing temperature is 950 ℃, the heat preservation time is 0.5h, and then quenching into ice water for cooling. And obtaining a mixture of the complete austenite copper aluminum manganese alloy and the spherical silica gel.

(5) And (4) immersing the mixture of the completely austenitic copper-aluminum-manganese alloy and the spherical silica gel in the step (4) into a hydrofluoric acid aqueous solution with the mass fraction of 20% for leaching. And (3) carrying out dissolution filtration at 35 ℃ by assisting ultrasonic vibration, replacing the solution every 5 hours, taking out the porous metal after the pore-forming agent is completely dissolved and filtered, washing the porous metal by using clear water by assisting ultrasonic vibration, and then drying the porous metal in a drying oven at the temperature of 80 ℃ for 7 hours to obtain the super-elastic micron porous copper-aluminum-manganese alloy matrix.

(6) Cutting the super-elastic micro-porous copper aluminum manganese alloy matrix obtained in the step (5) into blocks of 8 multiplied by 1mm, cleaning oil stains, and immersing into HCl-FeCl with the mass fraction of 20%₃Aqueous solution (hydrochloric acid with the mass fraction of 20 percent, 20g FeCl is added in each 100mL₃) Dealloying treatment is carried out, dealloying temperature is 60 ℃, dealloying time is 60 min. Then, the de-alloyed sample is cleaned by deionized water and ultrasonic vibration, and then is put into a vacuum drying oven for drying, wherein the vacuum degree is 6 multiplied by 10^-3And (3) the temperature is 90 ℃ below Pa, and the time is 8 hours, so that the dual-scale porous copper-aluminum-manganese composite current collector is prepared. The XRD diffractogram (figure 11) shows that the sample composition phase after 60min of dealloying is a composite phase of pure copper and beta phase. Observing the surface morphology of the micron pores, as shown in fig. 12, finding that a layer of nano porous structure is generated on the surface of the pores of the sample after 60min of dealloying, wherein the size of the pores is 100-200 nm.

Example 3

(1) Weighing the pure copper blocks, the pure aluminum blocks and the pure manganese blocks according to the mass percentage of 81:10:11, and then obtaining the copper-aluminum-manganese alloy cast ingot through induction melting.

(2) Screening original silica gel particles with the diameter of 0.45-0.71 mm, putting the particles into a muffle furnace, preserving heat for 1h at 180 ℃ for dehydration, and then preserving heat for 2h at 980 ℃ for modification treatment, so that the particles expand and lose the water absorption effect. And screening out spherical silica gel pore-forming agent with the diameter of 0.71-1 mm after the material is cooled along with the furnace.

(3) Keeping an alumina crucible vertical, sequentially putting the spherical silica gel pore-forming agent obtained in the step (2), a circular ceramic sieve pore sheet (the thickness is 1mm, and the aperture of a sieve pore is 2mm) and the copper-aluminum-manganese alloy cast ingot obtained in the step (1), and putting the loaded crucible into a vertical tubular furnace; the tube furnace is evacuated to 8X 10^-3Pa below, heating to 1100 deg.C, and maintaining the temperature30min, after the alloy is completely melted, closing the vacuum pump, adding high-purity argon to 0.3MPa, preserving the heat for 5min to ensure that the molten metal completely permeates into gaps of the pore-forming agent, then maintaining the pressure and cooling to room temperature along with the furnace to obtain a mixture of the copper-aluminum-manganese alloy and the spherical silica gel

(4) And (4) putting the mixture of the copper-aluminum-manganese alloy and the spherical silica gel prepared in the step (3) into a muffle furnace for austenitizing treatment, wherein the austenitizing temperature is 930 ℃, the heat preservation time is 1h, and then quenching into ice water for cooling. And obtaining a mixture of the complete austenite copper aluminum manganese alloy and the spherical silica gel.

(5) And (4) immersing the mixture of the complete austenite copper-aluminum-manganese alloy and the spherical silica gel in the step (4) into an HF solution with the mass fraction of 10% for leaching. And (3) carrying out dissolution filtration at 50 ℃ by assisting ultrasonic vibration, replacing the solution every 6 hours, taking out the porous metal after the pore-forming agent is completely dissolved and filtered, cleaning the porous metal by using clear water by assisting ultrasonic vibration, and then drying the porous metal in a drying oven at the temperature of 100 ℃ for 6 hours to obtain the super-elastic micron porous copper-aluminum-manganese alloy matrix.

(6) Cutting the super-elastic micro-porous copper aluminum manganese alloy matrix obtained in the step (5) into blocks of 8 multiplied by 1mm, cleaning oil stains, and immersing into HCl-FeCl with the mass fraction of 10%₃Aqueous solution (10% hydrochloric acid per 100 mL)

Adding 10g FeCl₃) Dealloying at 50 deg.C for 90min, cleaning dealloyed sample with deionized water and ultrasonic vibration, and drying in vacuum drying oven with vacuum degree of 6 × 10^-3And (4) the temperature is 80 ℃ and the time is 12 hours below Pa, and the dual-scale porous copper-aluminum-manganese composite material current collector is prepared. The XRD diffractogram (fig. 13) shows that the main diffraction peak of the sample after 90min of dealloying is pure copper, but there is still a small amount of diffraction peak of beta phase, indicating that most of the beta phase skeleton has been corroded. SEM characterization is carried out on the porous framework (figure 14), and a layer of nano porous structure is generated on the original pore framework of the sample after 90min of dealloying, wherein the size of pores is 200-300 nm.

Claims

1. The preparation method of the dual-scale porous copper-aluminum-manganese shape memory alloy composite material is characterized by comprising the following steps of:

(3) sequentially putting the spherical silica gel pore-forming agent obtained in the step (2), the round ceramic sieve pore sheet and the CuAlMn alloy cast ingot obtained in the step (1) into a crucible; placing the loaded crucible into the inner cavity of a vertical tube furnace, vacuumizing the tube furnace to 8 x 10^-3Heating to 1090-1110 ℃ below Pa, preserving heat for 15-30 min, then closing a vacuum pump, introducing high-purity argon, keeping the pressure in the furnace chamber at 0.1-0.3 MPa, continuing preserving heat at the temperature for 3-5 min, and then cooling the pressure maintaining furnace to room temperature to obtain a mixture of the CuAlMn alloy and the spherical silica gel;

(4) putting the mixture of the CuAlMn alloy and the spherical silica gel prepared in the step (3) into a muffle furnace for austenitizing treatment to obtain a mixture of a fully austenitic copper-aluminum-manganese alloy and the spherical silica gel; the austenitizing treatment is to preserve heat for 0.5 to 3 hours at the temperature of 850 to 950 ℃, and then to cool, wherein the cooling mode is to quench into ice water for cooling;

2. The method for preparing a dual-scale porous copper aluminum manganese shape memory alloy composite material according to claim 1, wherein the purity of the pure Cu, pure Al and pure Mn raw materials in step (1) is 99% or more in mass percentage.

3. The method for preparing the dual-scale porous copper aluminum manganese shape memory alloy composite material according to claim 1, wherein the original silica gel particle size in step (2) is 0.45-0.71 mm; the silica gel dehydration treatment temperature is 150-220 ℃, and the heat preservation time is 0.5-1 h.

4. The preparation method of the dual-scale porous copper-aluminum-manganese shape memory alloy composite material according to claim 1, wherein the modification treatment temperature in the step (2) is 950-1000 ℃, and the heat preservation time is 1-2 hours.

5. The method for preparing the dual-scale porous copper-aluminum-manganese shape memory alloy composite material according to claim 1, wherein the diameter of the ceramic mesh sheet in the step (3) is 0.5 to 1mm smaller than that of the alumina crucible, the pore diameter of the mesh is 1 to 2mm, and the thickness of the mesh is 1 to 2mm, so that the composite material is used for supporting the CuAlMn alloy ingot to separate the CuAlMn alloy ingot from the pore-forming agent, and the later stage pressurization does not prevent the liquid metal from flowing and permeating; the material does not react with molten metal and is high temperature resistant ceramic.

6. The method for preparing the dual-scale porous copper-aluminum-manganese shape memory alloy composite material according to claim 1, wherein the drying in the step (5) is drying in a drying oven at 60-100 ℃ for 6-8 h.

7. The method of making a dual-scale porous copper aluminum manganese shape memory alloy composite of claim 1The method is characterized in that the solution containing chloride ions in the step (6) is an aqueous solution or an organic solution, and the concentration of the chloride ions is 0.1-20 wt.%; the dealloying time in the step (6) is 0.5-3 h, and the dealloying temperature is 0-90 ℃; washing in the step (6) is washing by deionized water and ultrasonic vibration; the drying in the step (6) is to place the mixture into a vacuum drying oven for drying, wherein the vacuum degree is 6 multiplied by 10^-3Pa below, the temperature is 80-100 ℃, and the time is 6-12 h.

8. A dual-scale porous copper aluminum manganese shape memory alloy composite characterized in that it is produced by the method of any one of claims 1 to 7.

9. Use of the dual-scale porous copper aluminum manganese shape memory alloy composite of claim 8 in a secondary battery electrode material.