Copper alloy current collector for aqueous zinc ion battery, production method and application thereof

Abstract

The application discloses a production method of a copper alloy current collector of a water-based zinc ion battery, wherein 0.1-3wt% of tin and the balance of copper are smelted through vacuum smelting to obtain a copper alloy ingot, and the copper alloy current collector of the water-based zinc ion battery is prepared through twice rolling and annealing treatment; the preparation process of the copper alloy current collector becomes simpler, the crystal of the copper alloy current collector is easy to implement and control, the copper alloy current collector can be produced in large quantities at one time with the aid of the vacuum smelting technology, the production cost is reduced, and the industrial production prospect is wide. The copper alloy current collector prepared by the application is applied to a negative electrode of the water-based zinc ion battery, the lattice matching degree of zinc and a substrate during deposition is improved, the dendrite growth is inhibited, the copper alloy current collector and zinc foil are assembled into an asymmetric battery, the zinc deposition / detachment reversibility can be kept high, and thus the coulomb efficiency of the asymmetric battery is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of negative electrodes of aqueous zinc ion batteries, and in particular to a copper alloy current collector, a production method and applications of aqueous zinc ion batteries. Background Art

[0002] Lithium-ion batteries occupy half of the current secondary battery market due to their advantages such as high energy density. However, safety accidents involving lithium-ion batteries occur frequently, and the price of metallic lithium is relatively high. Therefore, people are constantly exploring solutions to replace lithium-ion batteries. Currently, aqueous zinc-ion batteries have attracted much attention due to their advantages of low cost and high safety.

[0003] However, the dendrite problem in the zinc negative electrode is a major reason that restricts the cycle life of zinc batteries. One of the solutions is current collector modification, which can be divided into three-dimensional current collector modification, surface coating modification, and alloy current collector modification. Among them, the first two are relatively expensive and are not suitable for large-scale production. The current alloy production process is relatively mature, and copper is often used as the negative electrode current collector. However, the deposition of zinc on pure copper will inevitably be accompanied by dendrite growth, so it is necessary to improve it. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a copper alloy current collector for aqueous zinc ion batteries, a production method and application thereof, which has low process cost, is easy to implement, inhibits dendrite growth, is applied to the negative electrode of aqueous zinc ion batteries and improves battery life.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a method for producing a copper alloy current collector for an aqueous zinc ion battery, comprising the following steps:

[0006] Step S1, weighing each metal powder according to weight percentage, including 0.1-3 wt% of tin and the balance of copper;

[0007] Step S2: transfer the metal powders into a graphite crucible, place the graphite crucible in a vacuum device, and make the vacuum chamber Vacuum degree Keep 20~1Pa ;

[0008] Step S3, heating and smelting, with the smelting temperature controlled at 900-1500° C., smelting until all the metal powder is melted, stopping heating, pouring in a vacuum chamber and cooling to room temperature to obtain a copper alloy ingot;

[0009] Step S4, cutting the copper alloy ingot into sheets with a thickness of 0.5 to 1 cm to obtain copper alloy sheets,

[0010] Step S5, performing a first rolling process on the copper alloy sheet to reduce the thickness of the copper alloy sheet to 200-400 μm by the first rolling process; and then performing a first annealing process on the copper alloy sheet.

[0011] The first annealing treatment includes a heating stage, a holding stage, and a cooling stage. Atmosphere protection is performed in the heating stage, the holding stage, and the cooling stage. In the heating stage, the heating rate is controlled at 5 to 10°C / min. In the holding stage, the annealing temperature is controlled at 400 to 500°C, and the annealing holding time is controlled at 1 to 4 hours. In the cooling stage, the copper alloy sheet is naturally cooled to room temperature in the atmosphere.

[0012] Step S6, performing a second rolling process on the copper alloy sheet that has undergone the first annealing process, reducing the thickness of the copper alloy sheet to 70-150 μm by the second rolling process, and then performing a second annealing process on the copper alloy sheet.

[0013] The second annealing treatment includes a heating stage, a holding stage and a cooling stage. Atmosphere protection is carried out in the heating stage, the holding stage and the cooling stage. In the heating stage, the heating rate is controlled at 5-10°C / min. In the holding stage, the annealing temperature is controlled at 400-500°C and the annealing holding time is controlled at 1-4 hours. In the cooling stage, the copper alloy sheet is naturally cooled to room temperature in the atmosphere.

[0014] A copper alloy current collector for aqueous zinc ion batteries is prepared.

[0015] Furthermore, during the first annealing treatment, the heating rate is controlled at 8-10°C / min in the heating stage, the annealing temperature is controlled at 400-450°C, and the annealing holding time is controlled at 1-2 hours in the holding stage; the thickness of the copper alloy sheet is thinned to 70-100 μm through the second rolling treatment, and during the second annealing treatment, the heating rate is controlled at 5-6°C / min in the heating stage, the annealing temperature is controlled at 460-500°C, and the annealing holding time is controlled at 0.5-1 hour in the holding stage.

[0016] Furthermore, in step S3, the melting temperature is controlled at 900-1000°C, and the melting time is controlled at 0.3-0.5 hours; in step S5, during the first annealing process and the second annealing process, the atmosphere used for the protective atmosphere is a mixed atmosphere of hydrogen and argon.

[0017] A copper alloy current collector for an aqueous zinc ion battery is prepared according to a production method for a copper alloy current collector for an aqueous zinc ion battery. The copper alloy current collector comprises 0.1 to 3 wt% of tin and the remainder of copper, as well as unavoidable impurity elements, wherein the tin element is completely dissolved in the copper matrix, and there is no enrichment of tin or copper elements at or within the grain boundaries. The grains are distributed in an equiaxed crystal shape, the grain radius is 2 to 5 microns, and the grain size in all directions is 1.5 to 2.5 microns. The difference is reduced to 0.1-0.5 microns .

[0018] Furthermore, the copper alloy current collector further comprises 0.1-3 wt% indium or 0.1-3 wt% silver by weight, wherein the indium element or silver element is completely dissolved in the copper matrix, and there is no enrichment of tin element, copper element, indium element or silver element at or within the grain boundaries, the grains are distributed in an equiaxed crystal shape, the grain radius is 2-3 microns, and the grain size in all directions is The difference is reduced to 0.1-0.3 microns .

[0019] Furthermore, the copper alloy current collector further comprises 0.1-1 wt% indium and 0.1-1 wt% silver by weight, wherein the tin, indium and silver elements are completely dissolved in the copper matrix, and there is no enrichment of tin, copper, indium or silver elements at or within the grain boundaries. The grains are distributed in an equiaxed shape, with a grain radius of 2-3 microns and a grain size in all directions. The difference is reduced to 0.1-0.3 microns .

[0020] The invention relates to an application of a copper alloy current collector in an aqueous zinc ion battery. The negative electrode of the aqueous zinc ion battery comprises a whole body obtained by pre-depositing a zinc sheet on the copper alloy current collector.

[0021] Compared with the prior art, the present invention has the following advantages: the present invention simplifies the preparation process of the copper alloy current collector, is easy to implement and easy to control the crystals of the copper alloy current collector, and can produce the copper alloy current collector in large quantities at one time with the help of vacuum melting technology, thereby reducing production costs and having broad prospects for industrial production.

[0022] The preparation method of the present invention thins the alloy by cutting and rolling technology, has no strict size requirements for the alloy ingot raw material, is applicable to most alloy materials, and introduces annealing during rolling to eliminate the stress influence caused by strain.

[0023] The copper alloy current collector prepared by the present invention is applied to the negative electrode of an aqueous zinc ion battery to improve the lattice matching degree between zinc and the substrate during deposition and inhibit dendrite growth. The copper alloy current collector and zinc foil are assembled into an asymmetric battery, which can maintain a high reversibility of zinc deposition / deposition, thereby significantly improving the coulombic efficiency of the asymmetric battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a flow chart for preparing the alloy current collector of the present invention;

[0025] Figure 2 The SEM image and EDS mapping image of the Cu-0.3Sn alloy current collector in Example 1 of the present invention;

[0026] Figure 3 TEM image of the Cu-0.3Sn alloy current collector in Example 1 of the present invention;

[0027] Figure 4 This is a half-cell cycle diagram of the Cu-0.3Sn alloy current collector in Example 2 of the present invention;

[0028] Figure 5 This is a SEM image of the Cu-2Sn alloy current collector in Example 3 of the present invention;

[0029] Figure 6 This is a half-cell cycle diagram of the Cu-2Sn alloy current collector in Example 3 of the present invention;

[0030] Figure 7 This is a half-cell cycle diagram of the Cu-1Sn alloy current collector in Example 4 of the present invention;

[0031] Figure 8 TEM image of the Cu-0.3Ag alloy current collector in Comparative Example 1 of the present invention;

[0032] Figure 9 TEM image of the Cu-0.3In alloy current collector in Comparative Example 2 of the present invention;

[0033] Figure 10 This is a half-cell cycle diagram of the Cu current collector in Comparative Example 3 of the present invention;

[0034] Figure 11 These are SEM images of the four current collectors of the present invention after cycle failure. DETAILED DESCRIPTION

[0035] Example 1

[0036] The preparation method of Cu-0.3Sn alloy current collector has the following process: composition design - melting - cutting - first rolling - first annealing - second rolling - second annealing - copper alloy current collector, such as Figure 1 shown.

[0037] Step S1, weighing 997g of copper and 3g of tin respectively;

[0038] Step S2, transferring the weighed metal into a graphite crucible, and placing the graphite crucible in a vacuum device with a vacuum degree of 2 Pa;

[0039] Step S3, the melting temperature is 950℃, after melting for 0.5h, pouring in the vacuum cavity and cooling to room temperature to obtain Cu-0.3Sn alloy ingot;

[0040] Step S4, cutting the Cu-0.3Sn alloy ingot into 2cm thick Cu-0.3Sn alloy sheet;

[0041] Step S5, after the first rolling to 200μm, the first annealing is carried out in the mixed atmosphere of hydrogen and argon at 450℃ for 2h, wherein the heating rate is 10℃ / min;

[0042] Step S6, the second rolling treatment is carried out to roll the Cu-0.3Sn alloy sheet after the first annealing treatment to the thickness of 100μm; finally, the second annealing treatment is carried out to carry out the first annealing in the mixed atmosphere of hydrogen and argon at 460℃ for 1h, wherein the heating rate is 5℃ / min, to obtain the Cu-0.3Sn alloy current collector.

[0043] Step S5 adopts the combined treatment of twice rolling and twice annealing, the second annealing treatment reduces the heating rate and increases the annealing temperature relative to the second annealing treatment, which not only reduces the processing energy consumption, but also reduces the difficulty of thinning, and also better and faster removes the internal stress of the copper alloy current collector.

[0044] The prepared Cu-0.3Sn alloy current collector is tested by SEM and TEM, and the microcharacteristics are shown in Figure 2 and Figure 3 respectively, wherein, Figure 2 is the grain image and EDS Mapping image of the Cu-0.3Sn alloy current collector, it can be seen that the grain is equiaxed grain, that is, the size difference in each direction is small, the grain radius size is 2-3 microns, and there is no single element enrichment in the three-way grain boundary and the grain, wherein Sn is uniformly solid-solved in the Cu matrix; Figure 3 is the TEM image of the Cu-0.3Sn alloy current collector, the atoms are uniformly and orderly arranged, and there is no precipitated phase, according to the calculation, the interplanar spacing is 0.185nm, compared with the interplanar spacing of pure copper, the interplanar spacing of the alloy increases after doping Sn.

[0045] The purpose of the first rolling treatment is to preliminarily thin the alloy thickness, stress will be generated in the alloy during the rolling process, which causes the alloy to harden and cannot be thinned further, so the first annealing is carried out to eliminate the internal stress; the purpose of the second rolling treatment is to make the alloy reach the expected thickness, and the actual thickness can be thinned according to the needs, and the purpose of the second annealing is the same as the first annealing, which is to eliminate stress and soften the alloy.

[0046] Example 2

[0047] The prepared Cu-0.3Sn current collector was assembled with zinc foil of commercial aqueous zinc ion battery into a half-cell, and the Cu-0.3Sn alloy current collector was tested.

[0048] The positive electrode is selected from one of a manganese-based compound, a vanadium-based compound, HATN or HATN-3CN; the separator is selected from one of a glass fiber separator, a cellulose separator, a polyethylene non-woven separator, and a microporous filter paper; the aqueous electrolyte is composed of a soluble salt and water, and the concentration of the soluble salt is 1 to 5 mol L -1 ;

[0049] The soluble salt includes one of zinc sulfate heptahydrate, zinc trifluoromethanesulfonate and zinc chloride, or the soluble salt is a mixture of at least two of zinc sulfate heptahydrate, zinc trifluoromethanesulfonate and zinc chloride.

[0050] Weigh 5.7512 g ZnSO4·7H2O, add 7.48 mL deionized water, prepare 2 M ZnSO4 as electrolyte, assemble the prepared Cu-0.3Sn current collector and commercial zinc foil into a half-cell, and conduct the reaction at 5 mA cm -2 , 1mAh cm -2 The coulombic efficiency and cycle stability were tested under the following conditions: Figure 4 As shown, it can maintain a stable cycle for more than 2600 turns.

[0051] Example 3

[0052] Preparation of Cu-2Sn alloy current collector, comprising the following steps:

[0053] Step S1, weighing 997g of copper and 20g of tin respectively;

[0054] Step S2, transferring the weighed metal into a graphite crucible, and placing the graphite crucible in a vacuum apparatus with a vacuum degree of 5 Pa;

[0055] Step S3, melting at a temperature of 1050° C. for 2 h, then pouring the resulting mixture into a vacuum chamber and cooling it to room temperature to obtain a Cu-2Sn alloy ingot;

[0056] Step S4, cutting the Cu-2Sn alloy ingot into 3 cm thick Cu-2Sn alloy sheets;

[0057] Step S5, after the first rolling to 250 μm, a first annealing treatment is performed in a mixed atmosphere of hydrogen and argon at 400° C. for 1 hour, wherein the heating rate is 5° C. / min;

[0058] Step S6, second rolling is performed, i.e., the Cu-2Sn alloy sheet after the first annealing treatment is rolled to a thickness of 80 μm; finally, second annealing treatment is performed, 400℃, 1 hour of second annealing treatment is performed in a mixed gas atmosphere of hydrogen and argon, to obtain the Cu-2Sn alloy current collector. The prepared Cu-2Sn alloy current collector is characterized by SEM, and the microstructure characteristics are shown in Figure 5 Most of the grains are equiaxed, and the grain size is uniform.

[0059] The prepared Cu-2Sn current collector and the commercial zinc foil of the aqueous zinc ion battery are assembled into a half battery.

[0060] 5.7512 g of ZnSO4·7H2O is weighed, 7.48 mL of deionized water is added, 2M ZnSO4 is prepared as an electrolyte, the prepared Cu-2Sn current collector and the commercial zinc foil are assembled into a half battery, and the coulombic efficiency and cycle stability are tested under the conditions of 5 mA cm -2 , 1 mAh cm -2 , as shown in Figure 6 , which can be kept stable for more than 2200 cycles.

[0061] Example 4

[0062] The Cu-1Sn alloy current collector is prepared by the following steps,

[0063] Step S1, 997 g of copper and 10 g of tin are weighed respectively;

[0064] Step S2, the weighed metals are moved into a graphite crucible, and the graphite crucible is placed in a vacuum device with a vacuum degree of 3 Pa;

[0065] Step S3, the melting temperature is 1050℃, and after 1 h of melting, the Cu-1Sn alloy ingot is poured and cooled to room temperature in the vacuum cavity;

[0066] Step S4, the Cu-1Sn alloy ingot is cut into a Cu-1Sn alloy sheet with a thickness of 1 cm;

[0067] Step S5, the first rolling is performed to 250 μm, and then 400℃, 1 hour of first annealing treatment is performed in a mixed gas atmosphere of hydrogen and argon, wherein the heating rate is 5℃ / min;

[0068] Step S6, second rolling is performed, i.e., the Cu-1Sn alloy sheet after the first annealing treatment is rolled to a thickness of 100 μm; finally, second annealing treatment is performed, which is the same as the first annealing treatment, to obtain the Cu-1Sn alloy current collector.

[0069] Weigh 5.7512 g ZnSO4·7H2O, add 7.48 mL deionized water, prepare 2 M ZnSO4 as electrolyte, assemble the prepared Cu-1Sn current collector and commercial zinc foil into a half-cell, and conduct the reaction at 5 mA cm -2 , 1mAh cm -2 The coulombic efficiency and cycle stability were tested under the following conditions: Figure 7 As shown, it can maintain a stable cycle for more than 2400 turns.

[0070] Comparative Examples 1-2

[0071] Cu-0.3Ag alloy current collector and Cu-0.3In alloy current collector were prepared.

[0072] According to the same process and test conditions as in Examples 1 to 2, Cu-0.3Ag alloy current collectors and Cu-0.3In alloy current collectors were prepared respectively. As shown in Table 1, doping a small amount of alloying elements in copper can adjust the interplanar spacing of the matrix, thereby reducing the mismatch with Zn, which is beneficial to the deposition of Zn on the current collector and improving battery performance. The three copper alloys proposed in this patent can achieve the above effects, among which the Cu-0.3Sn current collector has the best effect. The TEM images of the Cu-0.3Ag and Cu-0.3In alloy current collectors are shown in Figure 1. Figure 8 and Figure 9 As shown, Figure 8 This is the TEM image of the Cu-0.3Ag alloy current collector. According to calculations, its interplanar spacing is 0.182nm. Figure 9 This is the TEM image of the Cu-0.3In alloy current collector, whose interplanar spacing is 0.184nm.

[0073] Comparative Example 3

[0074] The negative electrode of the aqueous zinc ion battery is a pure copper current collector, and the cycle test diagram is as follows Figure 10 shown.

[0075] Example Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Alloy composition Cu-0.3Sn Cu-0.3Ag Cu-0.3In Cu interplanar spacing 0.185nm 0.182nm 0.184nm 0.181nm Lattice mismatch with Zn 11.5％ 12.9％ 12.0％ 13.4％ Half-cell stable cycle number 2600 1500 1100 500

[0076] Table 1 - Comparison of alloy characteristics and properties of examples and comparative examples

[0077] After the cycle is completed, the battery is disassembled and the current collector is characterized by SEM, such as Figure 10As shown in the figure, vertical dendrite protrusions grow on the pure Cu current collector, which will pierce the diaphragm and cause battery short circuit during battery cycling; the Zn deposition on the Cu-0.3Ag current collector is messy, with uneven size and thickness, which may lead to unstable battery cycling; dead zinc falls off on the Cu-0.3Ag current collector, which will lead to a decrease in available Zn in subsequent cycles, thereby reducing battery performance; while the Zn on the Cu-0.3Sn current collector is deposited in a flat and dense manner, without obvious protrusions, which can improve battery performance.

[0078] The present invention alloys copper with other metals to improve the lattice compatibility between zinc and the current collector atoms, thereby increasing the reversibility of zinc deposition / deposition on the current collector, inhibiting dendrite growth, and increasing battery life. Therefore, the industrial application prospects of the alloy current collector are relatively broad.

[0079] The present invention applies a copper alloy current collector to the negative electrode of an aqueous zinc ion battery, which can uniformly induce zinc deposition. The copper alloy current collector of the present invention can regulate the dissolution and deposition behavior of zinc ions in the battery. The copper alloy current collector and zinc foil are assembled into an asymmetric battery, which can maintain high reversibility of zinc deposition and removal, uniformly induce zinc deposition and inhibit dendrite growth, thereby significantly improving the coulombic efficiency of the asymmetric battery.

Claims

1. A method for producing a copper alloy current collector for an aqueous zinc ion battery, characterized in that: The following steps are included: Step S1, weighing each metal powder according to weight percentage, including 0.1-3 wt% of tin and the balance of copper; Step S2, moving each metal powder into a graphite crucible, placing the graphite crucible in a vacuum device, and maintaining the vacuum degree of the vacuum chamber at 20-1 Pa; Step S3, heating and smelting, with the smelting temperature controlled at 900-1500° C., stopping heating after smelting until all the metal powder is melted, pouring in a vacuum chamber and cooling to room temperature to obtain a copper alloy ingot; Step S4, cutting the copper alloy ingot into sheets with a thickness of 0.5 to 1 cm to obtain copper alloy sheets, Step S5, performing a first rolling process on the copper alloy sheet to reduce the thickness of the copper alloy sheet to 200-400 μm by the first rolling process; and then performing a first annealing process on the copper alloy sheet. The first annealing treatment includes a heating stage, a holding stage, and a cooling stage. Atmosphere protection is performed in the heating stage, the holding stage, and the cooling stage. In the heating stage, the heating rate is controlled at 5 to 10°C / min. In the holding stage, the annealing temperature is controlled at 400 to 500°C, and the annealing holding time is controlled at 1 to 4 hours. In the cooling stage, the copper alloy sheet is naturally cooled to room temperature in the atmosphere. Step S6, performing a second rolling process on the copper alloy sheet that has undergone the first annealing process, reducing the thickness of the copper alloy sheet to 70-150 μm by the second rolling process, and then performing a second annealing process on the copper alloy sheet. The second annealing treatment includes a heating stage, a holding stage and a cooling stage. Atmosphere protection is carried out in the heating stage, the holding stage and the cooling stage. In the heating stage, the heating rate is controlled at 5-10°C / min. In the holding stage, the annealing temperature is controlled at 400-500°C and the annealing holding time is controlled at 1-4 hours. In the cooling stage, the copper alloy sheet is naturally cooled to room temperature in the atmosphere. A copper alloy current collector for aqueous zinc ion batteries is prepared.

2. The method for producing a copper alloy current collector for an aqueous zinc ion battery according to claim 1, wherein: During the first annealing treatment, the heating rate is controlled at 8-10°C / min in the heating stage, the annealing temperature is controlled at 400-450°C, and the annealing holding time is controlled at 1-2 hours in the holding stage; the thickness of the copper alloy sheet is thinned to 70-100 μm through the second rolling treatment, and during the second annealing treatment, the heating rate is controlled at 5-6°C / min in the heating stage, the annealing temperature is controlled at 460-500°C, and the annealing holding time is controlled at 0.5-1 hour in the holding stage.

3. The method for producing a copper alloy current collector for an aqueous zinc ion battery according to claim 1, wherein: In the step S3, the melting temperature is controlled at 900-1000° C., and the melting time is controlled at 0.3-0.5 hours. In the step S5, during the first annealing process and the second annealing process, the atmosphere used for the protective atmosphere is a mixed atmosphere of hydrogen and argon.

4. A copper alloy current collector for an aqueous zinc ion battery, characterized in that: The copper alloy current collector for an aqueous zinc ion battery according to any one of claims 1 to 3 is prepared, wherein the copper alloy current collector comprises, by weight percentage, 0.1 to 3 wt% of tin and the remainder of copper, as well as unavoidable impurity elements, wherein the tin element is completely dissolved in the copper matrix, and there is no enrichment of tin or copper elements at or within the grain boundaries. The grains are distributed in an equiaxed crystal shape, the grain radius is 2 to 5 microns, and the size difference of the grains in all directions is reduced to 0.1 to 0.5 microns.

5. The copper alloy current collector for an aqueous zinc ion battery according to claim 4, wherein: The copper alloy current collector further includes 0.1 to 3 wt% of indium or 0.1 to 3 wt% of silver by weight, wherein the indium element or the silver element is completely dissolved in the copper matrix, and there is no enrichment of tin element, copper element, indium element or silver element at or within the grain boundaries. The grains are distributed in an equiaxed crystal shape, the grain radius is 2 to 3 microns, and the size difference of the grains in all directions is reduced to 0.1 to 0.3 microns.

6. The copper alloy current collector for an aqueous zinc ion battery according to claim 4, wherein: The copper alloy current collector further includes 0.1-1 wt% of indium and 0.1-1 wt% of silver by weight, wherein tin, indium and silver are completely dissolved in the copper matrix, and there is no enrichment of tin, copper, indium or silver at or within the grain boundaries. The grains are distributed in an equiaxed crystal shape, the grain radius is 2-3 microns, and the size difference of the grains in all directions is reduced to 0.1-0.3 microns.

7. Use of the copper alloy current collector according to any one of claims 2 to 4 in an aqueous zinc ion battery, characterized in that: The negative electrode of the aqueous zinc ion battery comprises a whole obtained by pre-depositing a zinc sheet on the copper alloy current collector according to any one of claims 2 to 4.

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