Preparation method of super (002) crystal face texture zinc metal negative electrode

Abstract

The application discloses a preparation method of a zinc metal negative electrode with superstrong (002) crystal face texture. The zinc metal with superstrong (002) crystal face texture is prepared by combining an annealing treatment process and a rolling process, and the (002) crystal face texture strength of the prepared zinc sheet is greater than 30. Compared with the prior art, the preparation method has the advantages of simple process and low cost, and can realize large-scale industrial production. The zinc sheet prepared by the application has excellent cycle stability when used in a water-based zinc ion battery.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a zinc metal negative electrode, in particular to a preparation method of a zinc metal negative electrode with super-strong (002) crystal face texture. BACKGROUND

[0002] Zinc ion batteries (ZIBs) are considered as a promising next-generation energy storage battery due to the high theoretical and volumetric capacity, low redox potential, safety and abundant zinc metal reserves of the zinc metal negative electrode. However, the zinc metal negative electrode has problems such as zinc dendrite growth and serious side reactions, which seriously restrict the development and industrial application of zinc ion batteries.

[0003] Studies have shown that the uniform deposition of zinc ions is closely related to the orientation of different crystal faces of the zinc negative electrode. For example, the zinc deposition on the zinc metal negative electrode surface dominated by (100) and (101) crystal faces is uneven, which will eventually form zinc dendrites to pierce the separator and cause the battery to fail. However, the deposition dominated by the (002) crystal face will be uniformly deposited along the direction parallel to the substrate, which will inhibit the formation of zinc dendrites and effectively improve the performance of zinc ion batteries.

[0004] Currently, the methods for adjusting the zinc crystal face orientation to obtain dendrite-free zinc negative electrodes mainly include: epitaxially depositing zinc with (002) crystal face texture on the surface of a graphene film through electrodeposition; mixing cellulose and graphene oxide to form a separator through a solution casting method, and inducing zinc ions to preferentially deposit in the (002) crystal face during the deposition of zinc ions; etching a zinc foil with phosphoric acid to expose the (002) crystal face and improve the exposure strength; using a sulfonate electrolyte to induce the deposition of zinc with (002) crystal face texture on the substrate by the strong interaction between the sulfonate anion and the zinc ion; and using metal plastic deformation to enhance the (002) crystal face texture by continuous rolling. However, most of the above methods are still in the laboratory stage. For example, the electrodeposition method and the heat treatment method are complex, and the plastic deformation is limited by the initial grain size. If the grain size is too small, the grain sliding will be hindered, and if the grain size is too large, the zinc foil will be brittle and broken during rolling. In addition, the synthesis of graphene is dangerous and expensive, and the cost of the sulfonate electrolyte is high, so it cannot be commercialized or industrialized. Most importantly, the zinc metal obtained by the above methods still has strong (101), (102) and (110) crystal faces, which is not conducive to uniform zinc deposition. SUMMARY

[0005] To overcome the shortcomings of existing technologies, this invention proposes a method for preparing a zinc metal anode with a high-strength (002) crystal texture. This invention combines annealing with rolling processes, optimizing the grain size of zinc metal and performing plastic deformation treatment through rolling to obtain zinc sheets with high-strength exposed (002) crystal surfaces. The preparation process of this invention is simple, low-cost, and suitable for large-scale industrial production. Using the zinc sheets prepared by this invention as the anode in aqueous zinc-ion batteries effectively suppresses side reactions on the anode surface and effectively inhibits zinc dendrite growth during zinc ion deposition, thus exhibiting excellent cycle stability.

[0006] The preparation method of the ultra-strong (002) crystal textured zinc metal anode proposed in this invention is achieved through the following technical solution.

[0007] This invention proposes a method for preparing a high-strength (002) crystal textured zinc metal anode, comprising the following steps:

[0008] Step (1): Place the zinc sheet in a high-temperature furnace and anneal it under an inert atmosphere; the annealing temperature is 200-400℃; the annealing time is 5-20h; remove it after cooling;

[0009] Step (2): The zinc sheet after annealing in step (1) is subjected to roll forming to make its grains slide along the (002) sliding surface, so that the deformation rate of the zinc sheet is greater than 100%, and a zinc sheet with high strength exposure of the (002) crystal surface is obtained.

[0010] To achieve the objectives of this invention, a preferred method for preparing an ultra-strong (002) crystal textured zinc metal anode is proposed.

[0011] As a preferred embodiment of the present invention, the average grain size of the zinc sheet after annealing in step (1) is 29-32 μm.

[0012] As a preferred embodiment of the present invention, the average grain size of the zinc sheet after annealing in step (1) is about 30 μm.

[0013] As a preferred embodiment of the present invention, the annealing temperature in step (1) is 250-350℃; the annealing time is 10-12h.

[0014] As a preferred embodiment of the present invention, the heating rate of the annealing process in step (1) is 1-20℃ / min.

[0015] As a preferred embodiment of the present invention, the zinc sheet in step (1) is zinc foil, preferably high-purity zinc foil with a purity > 99.9%.

[0016] As a preferred embodiment of the present invention, the zinc sheet is cleaned and dried before the annealing process in step (1); preferably, the zinc sheet is ultrasonically cleaned with ethanol and acetone and dried at room temperature.

[0017] As a preferred embodiment of the present invention, the inert atmosphere in step (1) is argon.

[0018] As a preferred embodiment of the present invention, the step (2) of rolling the annealed zinc sheet by roller pressing specifically involves placing the zinc sheet between two rollers of a roller press for rolling; gradually reducing the working distance between the two rollers during the rolling process until the deformation rate of the zinc sheet is greater than 100%.

[0019] As a preferred embodiment of the present invention, the step (2) of rolling the annealed zinc sheet by roller pressing is specifically as follows: the zinc sheet is placed between two rollers of the roller press for rolling; during the rolling process, the working distance between the two rollers is gradually reduced until the deformation rate of the zinc sheet is greater than 300%.

[0020] The formula for calculating the deformation rate is: ε=(t0-t) / t, where ε is the deformation rate, t0 is the original thickness of the zinc sheet, and t is the thickness of the zinc sheet after rolling.

[0021] The zinc sheet prepared by the method described in this invention, which combines annealing and rolling processes, has a median grain size greater than 100 μm, which can reduce grain boundary density and thus suppress side reactions such as hydrogen evolution and corrosion.

[0022] The zinc sheet obtained by the preparation method described in this invention has an ultra-strong (002) crystal texture and the (002) crystal texture intensity is greater than 30, thereby inhibiting the growth of zinc dendrites and suppressing surface side reactions, thereby improving the cycle life of the zinc metal anode.

[0023] The present invention proposes a method for preparing a high-strength (002) crystal textured zinc metal anode, which combines annealing and rolling processes, and has the following beneficial effects:

[0024] (1) Based on the theory of metal plastic deformation, this invention first anneals the zinc sheet, and then controls the zinc grain size by adjusting the annealing process conditions. Afterwards, a rolling mill is used to roll the zinc sheet, causing the grains to slide along the (002) slip plane, thereby greatly increasing the exposure strength of the (002) crystal plane of the zinc metal, resulting in zinc metal with an ultra-strong (002) crystal texture. This invention optimizes the grain size, enabling zinc metal that was originally unable to form a (002) crystal texture under rolling plastic deformation treatment due to the initial grain size to be prepared with an ultra-strong (002) crystal texture through a simple rolling process.

[0025] (2) Since the (002) crystal plane can induce zinc ions to grow in the same preferred orientation, they can eventually be deposited uniformly in a direction parallel to the substrate. This will suppress the formation of zinc dendrites and effectively improve the performance of zinc-ion batteries. The (002) crystal plane texture intensity of the zinc sheet obtained by this invention is greater than 30, which effectively suppresses the growth of zinc dendrites and suppresses surface side reactions, thereby improving the cycle life of the zinc metal anode.

[0026] (3) The preparation process proposed in this invention is simple and low in cost, and compared with the existing technology, it can achieve large-scale industrial production.

[0027] (4) The zinc sheet prepared by this invention, when used as the negative electrode in an aqueous zinc-ion battery (or in an aqueous zinc-ion capacitor), exhibits excellent cycle stability at 0.1 mA / cm². 2 and 0.1mAh / cm 2 Under the specified testing conditions, it can cycle for over 3000 hours. At 10mA / cm... 2 and 10mAh / cm 2 Under the test conditions, it can be cycled for more than 200 hours. Attached Figure Description

[0028] Figure 1 An optical micrograph of a zinc sheet; Figure 1 a represents the original zinc sheet; Figure 1 b represents the zinc sheet after annealing. Figure 1 c is a micrograph of the zinc sheet after annealing and subsequent roll forming when the deformation rate reaches 360%.

[0029] Figure 2 This is a diagram showing the grain size distribution of zinc sheets. Figure 2 a represents the original zinc sheet grain size distribution; Figure 2 b represents the grain size distribution of the zinc sheet after annealing.

[0030] Figure 3 The image shows the XRD pattern of the zinc sheet prepared according to this invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0032] The rolling mill used in this invention is an electric rolling mill with adjustable sheet thickness. Depending on the shape and size of the workpiece, rolling mills with different roll widths and different sheet thickness ranges can be selected.

[0033] The following are specific examples:

[0034] Example 1: This example provides a method for preparing a high-strength (002) crystal textured zinc metal anode, the preparation method comprising the following steps:

[0035] (1) High-purity zinc foil (99.9%) was ultrasonically cleaned with ethanol and acetone and dried at room temperature. Figure 1 a);

[0036] (2) Place the zinc foil in a tube furnace, set the appropriate annealing temperature and holding time, and anneal it under a protective atmosphere. After cooling, remove it. Figure 1 b);

[0037] (3) An adjustable thickness roller press is used to roll-press the annealed zinc foil; Figure 1 c);

[0038] The annealing temperature was 300℃, the heating rate was 1℃ / min, the holding time was 10h, and the protective atmosphere was argon. The average grain size after annealing was approximately 30μm. The annealed zinc foil was placed between two rollers of a rolling mill for rolling. During the rolling process, the working distance between the two rollers was gradually reduced until the deformation rate of the zinc foil reached 360%. The median grain size of the zinc foil after rolling was approximately 200μm, and the final zinc foil (002) crystal texture strength reached 38.

[0039] The prepared zinc foil was directly used as an electrode to assemble a zinc metal symmetric cell for electrochemical performance testing. It exhibited excellent cycle stability at 0.1 mA / cm². 2 and 0.1mAh / cm 2 Under the specified testing conditions, it can cycle for over 3000 hours. At 10mA / cm... 2 and 10mAh / cm 2 Under the test conditions, it can be cycled for more than 200 hours.

[0040] Example 2: This example provides a method for preparing a high-strength (002) crystal textured zinc metal anode, the preparation method comprising the following steps:

[0041] (1) High-purity zinc foil (99.9%) was ultrasonically cleaned with ethanol and acetone and then dried at room temperature;

[0042] (2) Place the zinc foil in a tube furnace, set the appropriate annealing temperature and holding time, and anneal it under a protective atmosphere. After cooling, take it out.

[0043] (3) An adjustable thickness roller press is used to roll the annealed zinc foil by rolling.

[0044] The annealing temperature was 250℃, the heating rate was 20℃ / min, the holding time was 70min, and the protective atmosphere was argon. The average grain size after annealing was approximately 30μm. The annealed zinc foil was placed between two rollers of a rolling mill for rolling. During the rolling process, the working distance between the two rollers was gradually reduced until the deformation rate of the zinc foil reached 300%. The median grain size of the zinc foil after rolling was approximately 200μm, and the final zinc foil (002) crystal texture strength reached 35.

[0045] The prepared zinc foil was directly used as an electrode to assemble a zinc metal symmetric cell for electrochemical performance testing. (At 1 mA / cm) 2 and 1mAh / cm 2 Under the test conditions, it can be cycled for more than 2000 hours.

[0046] Comparative Example 1:

[0047] (1) High-purity zinc foil (99.9%) was ultrasonically cleaned with ethanol and acetone and then dried at room temperature;

[0048] (2) The zinc foil is rolled using a thickness-adjustable roller press.

[0049] The zinc foil is placed between two rollers of a rolling mill for rolling; during the rolling process, the working distance between the two rollers is gradually reduced until the deformation rate of the zinc foil reaches 360%, and the final zinc foil (002) crystal texture strength is 8.

[0050] The obtained zinc foil was directly used as an electrode to assemble a zinc metal symmetric cell for electrochemical performance testing at 0.1 mA / cm². 2 and 0.1mAh / cm 2 Under the test conditions, it can only be cycled for 40 hours.

[0051] The above are merely embodiments of the present invention, described in a relatively specific and detailed manner, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength (002) crystal textured zinc metal anode, characterized in that, Includes the following steps: Step (1): Place the zinc sheet in a high-temperature furnace and anneal it under an inert atmosphere; the annealing temperature is 200°C. 400℃; annealing time is 5 minutes. 20 hours; remove after cooling; Step (2): The zinc sheet after annealing in step (1) is subjected to roll forming to make its grains slide along the (002) sliding surface, so that the deformation rate of the zinc sheet is greater than 100%, and a zinc sheet with high strength exposure of the (002) crystal surface is obtained.

2. The method for preparing a high-strength (002) crystal textured zinc metal anode according to claim 1, characterized in that, The average grain size of the zinc sheet after annealing in step (1) is 29. 32μm.

3. The method for preparing a super-strong (002) crystal textured zinc metal anode according to claim 1, characterized in that, Step (1) Annealing temperature is 250°C 350℃; annealing time is 10 minutes. 12h.

4. The method for preparing a super-strong (002) crystal textured zinc metal anode according to claim 1, characterized in that, The heating rate for the annealing process in step (1) is 1. 20℃ / min.

5. The method for preparing a super-strong (002) crystal textured zinc metal anode according to claim 1, characterized in that, The zinc sheet mentioned in step (1) is zinc foil, and the zinc foil purity is >99.9%.

6. The method for preparing a super-strong (002) crystal textured zinc metal anode according to claim 1, characterized in that, Step (1) Before annealing, the zinc sheet is cleaned and dried; the zinc sheet is ultrasonically cleaned with ethanol and acetone and dried at room temperature.

7. The method for preparing a super-strong (002) crystal textured zinc metal anode according to claim 1, characterized in that, The inert atmosphere mentioned in step (1) is argon.

8. The method for preparing a super-strong (002) crystal textured zinc metal anode according to claim 1, characterized in that, In step (2), the annealed zinc sheet is subjected to roll forming, specifically: the zinc sheet is placed between two rollers of the roll forming machine for rolling; during the rolling process, the working distance between the two rollers is gradually reduced until the deformation rate of the zinc sheet is greater than 100%.

9. The method for preparing a super-strong (002) crystal textured zinc metal anode according to claim 1, characterized in that, In step (2), the annealed zinc sheet is subjected to roll forming, specifically: the zinc sheet is placed between two rollers of the roll forming machine for rolling; during the rolling process, the working distance between the two rollers is gradually reduced until the deformation rate of the zinc sheet is greater than 300%.

10. The method for preparing a super-strong (002) crystal textured zinc metal anode according to claim 1, characterized in that, The median grain size of the zinc sheet after annealing and rolling is greater than 100 μm; the texture intensity of the (002) crystal plane of the zinc sheet is greater than 30.

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