Composite zinc anode for aqueous zinc ion battery as well as preparation method and application of composite zinc anode

Abstract

The invention relates to the field of aqueous zinc ion batteries, and discloses a preparation method and application of a composite zinc anode material. The invention aims to design a novel Zn-Gr composite anode, and Gr and zinc are synchronously deposited by adopting an electro-deposition method. A large number of pi electrons on Gr interact with dipole moments formed by inducing zinc ions and generate adsorption, and the spontaneous adsorption behavior allows the Gr to be self-assembled on a zinc layer to form a Zn-Gr-Zn-Gr... composite structure. Based on the zinc-loving characteristic of Gr, two advanced zinc anode modification strategies are fused, and the synergistic effect of the composite material is exerted. The zinc deposition thermodynamics is obviously improved, the conductivity is enhanced, and the growth of dendritic crystals and other side reactions are effectively inhibited, so that the battery has the advantages of high stability, long cycle life and the like, and the electrode performance is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of aqueous zinc ion battery anode materials, and particularly relates to a preparation method and application of a zinc / graphene composite anode. Background Art

[0002] Aqueous zinc-ion batteries (AZIBs) have attracted considerable attention due to their high safety, low cost, high theoretical capacity, and low redox potential. To date, significant progress has been made in the development of energy storage mechanisms and new materials for AZIBs cathode materials. However, the development of anodes is still hampered by uncontrolled dendrite growth, hydrogen evolution reaction (HER), and severe corrosion. Therefore, to advance the commercialization of aqueous zinc-ion batteries, current researchers are focusing their research on interface modification, three-dimensional structures, organic framework membranes, and electrolyte regulation. Currently, the design and modification of zinc anodes themselves are limited to constructing neat crystal planes, such as Zn(002) and Zn(101), which has certain limitations. If existing advanced technologies can be integrated, zinc anodes are expected to achieve a performance improvement of 1+1>2.

[0003] The low surface energy of the Zn(002) crystal plane can maintain thermodynamically stable physical and chemical properties and is considered to be an effective solution for constructing an ideal high-performance dendrite-free zinc anode. Graphene (Gr) has unique physical and chemical properties, such as high electrical conductivity, high thermal conductivity, high strength and large specific surface area. It is worth noting that Gr was found to have a lattice mismatch δ≈7% with the Zn(002) crystal plane, indicating that the two can form a semi-coherent interface with very small interfacial energy and slightly large elastic strain energy, thus meeting the selection criteria for a substrate for zinc metal deposition to lock the crystal orientation. Interestingly, highly dense Zn(002) crystal plane-oriented zinc foil can be prepared by electrochemical deposition using a high constant current density on a non-textured substrate (Cu, Ti, stainless steel plate, etc.), which is simpler and more reliable than the preparation method of using Gr as a base coating to lock the crystal deposition orientation. At the same time, many researchers have used Gr to modify the interface of zinc foil. Although this method balances the interfacial electric field, exerts a spatial shielding effect, and inhibits hydrogen evolution and the formation of a passivation layer, the Gr base coating still blocks the migration path of active zinc to a certain extent. In order to fully utilize the excellent affinity between Gr and zinc metal and its excellent electrochemical performance, a new zinc anode modification strategy is urgently needed.

[0004] This work designed a novel Zn-Gr composite anode, using a simple pulsed electrodeposition method to simultaneously deposit Gr and zinc. The abundant π electrons on Gr interact with the induced dipole moment of zinc ions, leading to adsorption. This spontaneous adsorption behavior allows Gr to self-assemble onto the zinc layer, forming a "Zn-Gr-Zn-Gr..." composite structure. This not only significantly improves zinc deposition thermodynamics and enhances conductivity, but also effectively suppresses dendrite growth and other side reactions, further enhancing electrode performance. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an aqueous zinc ion battery negative electrode material and its preparation method and application. The problem to be solved by the present invention is to overcome the existing technical defects and provide a zinc / graphene composite anode with a zinc layer as the matrix, stable structure and good electrode performance.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] In the first step, the concentration of 0.001-10 g L -1 The graphene solution is set aside.

[0008] In the second step, the graphene solution is added to the electrodeposition solution to achieve co-deposition of zinc metal and graphene.

[0009] The third step is to completely peel off the electrochemically deposited foil to obtain the zinc / graphene composite anode material.

[0010] Preferably, the Zn(002) crystal plane of the electrodeposited composite zinc anode is a preferred orientation.

[0011] Preferably, the thickness of the composite zinc anode does not exceed 1 mm.

[0012] The present invention further provides a zinc ion battery, comprising a zinc / graphene composite anode prepared by the method for preparing a composite zinc anode material for an aqueous zinc ion battery.

[0013] The preparation of the zinc / graphene composite anode and the zinc ion battery provided by the present invention have the following advantages over the prior art:

[0014] The present invention relates to a composite zinc anode material for aqueous zinc ion batteries, which can solve the problem of poor cycle performance caused by the corrosion resistance of zinc negative electrodes during the cycle process. Under high constant current density, Zn and Gr are co-deposited to prepare a composite anode with a Zn (002) texture. During deposition, a large number of π electrons in Gr induce zinc ions to generate dipole moments and interact with them to cause Gr to spontaneously adsorb. The good physical and chemical properties of Gr not only make the Zn (002)-Gr electrode have excellent corrosion resistance and mechanical strength, but also improve the electrode conductivity; at the same time, Zn 2+ The active induction of Gr leads to regular arrangement. Therefore, the present invention integrates two advanced zinc anode modification strategies based on the zinc affinity of Gr, and exerts the synergistic effect of the composite material.

[0015] The preparation method of the present invention provides an effective way to obtain the above-mentioned composite zinc anode material with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are incorporated into and constitute a part of this specification, illustrate embodiments consistent with the present invention, and together with the description, serve to explain the principles of the present invention. In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the description of the embodiments or the prior art.

[0017] Figure 1 The XRD patterns of Examples 1 and 2 and Comparative Example 1 are shown.

[0018] Figure 2 This is the SEM image of Example 2.

[0019] Figure 3 The cycle life of the symmetrical batteries assembled in Examples 1-2 and Comparative Example 1.

[0020] Figure 4 The graph shows the cycle performance and coulombic efficiency of the full battery composed of Examples 1-2 and Comparative Example 1 and β-MnO2. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to specific embodiments.

[0022] Example 1:

[0023] The preparation method of the Zn(002) negative electrode material of this embodiment includes the following steps:

[0024] A certain mass ratio of H₃BO₃, NaCl, and Zn(AC)₂ was added to deionized water and stirred to dissolve. A high-purity zinc plate was used as the anode, and a stainless steel mirror plate was used as the cathode. A constant-current pulse electrodeposition method was used to prepare the negative electrode material. MnO₂, acetylene black, and PVDF were mixed in a ratio of 7:2:1, coated on a stainless steel mesh, and dried to obtain a positive electrode. The electrolyte was a mixed solution of ZnSO₄ and MnSO₄. The separator was glass fiber. A full battery was assembled and the battery's cycling performance was tested. Example 1 is labeled Zn(002).

[0025] Example 2:

[0026] The preparation method of the Zn(002)-Gr negative electrode material of this embodiment includes the following steps:

[0027] Add H3BO3, NaCl and Zn(AC)2 in a certain mass ratio into deionized water, stir and dissolve, then add graphene at a concentration of 0.03 g L -1. A composite negative electrode material can be successfully prepared by using a high-purity zinc plate as the anode and a stainless steel mirror plate as the cathode using a constant current pulse electrodeposition method. MnO2, acetylene black and PVDF are mixed in a ratio of 7:2:1, coated on a stainless steel mesh, and dried to obtain a positive electrode sheet; the electrolyte is a mixed solution of ZnSO4 and MnSO4; the diaphragm is glass fiber; a full battery is assembled and the battery cycle performance is tested. The performance test of the above negative electrode material is the same as that of Example 1. Example 2 is marked as Zn(002)-Gr.

[0028] Example 3

[0029] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0030] Add H3BO3, NaCl and Zn(AC)2 in a certain mass ratio into deionized water, stir and dissolve, then add graphene at a concentration of 0.04 g L -1 A composite negative electrode material was successfully prepared using a high-purity zinc plate as the anode and a stainless steel mirror plate as the cathode using a constant current pulse electrodeposition method. MnO2, acetylene black, and PVDF were mixed in a ratio of 7:2:1, coated on a stainless steel mesh, and dried to obtain a positive electrode sheet. The electrolyte was a mixed solution of ZnSO4 and MnSO4; the separator was glass fiber. A full battery was assembled and the battery cycle performance was tested. The performance testing of the above negative electrode material was the same as in Example 2.

[0031] Comparative Example 1:

[0032] The preparation method of the bare zinc negative electrode material of this comparative example comprises the following steps:

[0033] The zinc foil surface was rinsed with distilled water and ethanol, cleaned, and dried to obtain bare zinc for later use. MnO2, acetylene black, and PVDF were mixed in a ratio of 7:2:1, coated on a stainless steel mesh, and dried to obtain a positive electrode sheet. The electrolyte was a mixed solution of ZnSO4 and MnSO4; the separator was glass fiber. Full cells were assembled and their cycling performance was tested. The performance testing of the above negative electrode materials was the same as in Example 1. Comparative Example 1 is labeled Commercial Zn.

[0034] Performance testing:

[0035] Figure 1 The XRD patterns of Examples 1-2 and Comparative Example 1 are shown. Compared with the standard PDF#04-0831 card, the peak contrast is completely consistent. Furthermore, the Zn(002)-Gr foil, under the adsorption of Gr, induces the growth of a higher-quality Zn(002) preferentially oriented composite foil, while suppressing the growth of hetero-oriented crystal planes such as Zn(100) and Zn(101).

[0036] Figure 2This is the SEM spectrum of Example 1. It shows that the zinc grains grow almost along the plane, the typical zinc hexagonal features are clearly visible, the average grain size is only 7-8 μm, and a small amount of Gr still remains on the grain surface.

[0037] Figure 3 This is the long cycle diagram of the symmetrical battery of Examples 1-2 and Comparative Example 1. -2 , 0.5 mAh cm -2 Under these conditions, Zn(002)-Gr exhibited stable cycling for over 7500 hours, a cycle life more than 23 times that of commercial zinc electrodes. The battery voltage experienced a gradual rise and fall during cycling (2000-3000 h) before stabilizing. Efficient zinc ion migration and electron transport ensured consistent reaction kinetics during the zinc anode's charge and discharge processes, promoting reversible reactions and further stabilizing voltage performance.

[0038] Figure 4 The long cycle diagram of the full battery composed of Examples 1-2 and Comparative Example 1 and MnO2. -1 Under the current density, Zn(002) generates byproducts and covers the active zinc metal, resulting in a rapid decrease in discharge capacity. After 1500 cycles, the capacity drops to below 50%. However, the Zn(002)-Gr full battery also experiences capacity decay (100 cycles) and can still provide effective active zinc metal for the positive electrode material to enter the activation state smoothly, supporting the battery to maintain 180 mAh cm -2 The above discharge specific capacity can be cycled up to 1800 cycles without any capacity decay.

[0039] In summary, the present invention effectively improves the performance of aqueous zinc-ion batteries. The above is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A composite zinc anode material for aqueous zinc ion batteries, characterized in that The invention comprises a zinc substrate and graphene embedded in the zinc layer.

2. A composite zinc anode material according to claim 1, characterized in that: The concentration of graphene used in the preparation process is 0.001-10 g L -1 .

3. A composite zinc anode material according to claim 1, characterized in that: The Zn(002) crystal plane of the composite zinc anode is a preferred orientation.

4. A composite zinc anode material according to claim 1, characterized in that: The thickness of the zinc / graphene composite anode does not exceed 1 mm.

5. A zinc ion battery comprising a zinc negative electrode, a positive electrode, a separator and an electrolyte, characterized in that: The zinc negative electrode is a zinc / graphene composite anode obtained by the preparation method according to any one of claims 1 to 3.

Images