A three-dimensional porous cluster composite electrode material and its preparation and application

Abstract

A three-dimensional open-pore cluster-like NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material grown in-situ on nickel foam and its preparation method. The addition of nickel foam in the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material enables the electrode material to be tightly combined with the surface of nickel foam; the morphology of the electrode material forms a cluster-like structure with larger open pores under the guidance of silver nanowires. At the same time, the silver nanowires are interspersed between the pores of nickel foam and are in direct contact with the NiMnO3 / Ni(OH)2 active material to form a conductive network, shortening the electron transfer distance, and its high conductivity further accelerates the electron transfer speed. The tight connection and interaction of each phase of the composite electrode material combine the high potential window of the oxide and the excellent specific capacitance of the hydroxide. The rapid electron transfer, rapid ion transfer, and more active sites exhibited by the material synergistically improve the electrochemical performance of the asymmetric supercapacitor.

Description

Technical Field

[0001] The present invention belongs to the technical field of supercapacitors, and particularly relates to a three-dimensional open-pore cluster structure NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material and its preparation and application. Background Art

[0002] Among the various transition metal oxides used for energy storage, binary nickel-manganese oxide has multiple redox reactions and better electrochemical activity. At the same time, nickel hydroxide is also at the forefront of research due to its unique layered structure, large interlayer spacing and high theoretical specific capacitance. However, due to the poor electrical conductivity of metal oxides / hydroxides, its actual specific capacity is limited. In addition, the agglomeration and accumulation of electrode materials can seriously affect ion / electron transmission, becoming an important bottleneck for their practical application in supercapacitors. In order to maximize the inherent advantages of both, it is necessary to design a nickel-manganese-based electrode material with a unique morphology and structure. The present invention uses nickel foam as a base material, and the composite material is tightly coupled with the collector (nickel foam) to improve ion / electron transmission, and has both the high potential window of the oxide and the high specific capacitance of the hydroxide; at the same time, an appropriate amount of silver nanowires is cited to significantly improve the electrical conductivity of the composite material and accelerate the electron transmission speed. Summary of the Invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a three-dimensional open-pore cluster structure NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material and its preparation and application, and solve the above-mentioned problems by increasing the number of exposed active sites to synergistically improve the conductivity and shorten the distance of ion transfer. The obtained composite material nanosheets grow in an interlaced manner along a fixed crystal plane under the guidance of silver nanowires to form a larger three-dimensional open-pore cluster structure. At the same time, the high conductivity of silver nanowires promotes electron transfer at the electrolyte / electrode interface and improves the electrical conductivity of the composite material, so that the NiMnO3 / Ni(OH)2 / AgNWs composite material is endowed with more excellent electrochemical properties, combining the high potential window of oxide and the high specific capacitance of hydroxide, and its preparation process is simple.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A three-dimensional open-pored clustered NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material, in which Ni(OH)2 nanosheets are the main units in the structure. Under the guidance of silver nanowires, they grow in an interlaced manner along fixed crystal planes to form a three-dimensional open-pored clustered structure; and some nanosheets are accumulated and attached to the silver nanowires.

[0006] In one embodiment, the width of the Ni(OH)2 nanosheets ranges from 0.3 nm to 3.8 nm. The combination between NiMnO3 and Ni(OH)2 can maximize the inherent advantages of both, endowing the composite electrode material with better electrochemical activity and thus a higher specific capacitance.

[0007] In one embodiment, the diameter of the silver nanowires is about 0.6 nm to 2.2 nm.

[0008] In one embodiment, under the action of Ag NWs, the nanosheets grow longitudinally along the (110) crystal direction, guiding the nanosheet-like structure of NiMnO3 / Ni(OH)2 to transform into a clustered structure with larger open pores. The three-dimensional open-pore clustered structure, where "three-dimensional" refers to a three-dimensional spatial structure, "open pores" refers to the pore structures present in the composite material, and "clustered" refers to the stacking manifestation of the pore structures in the composite material, and its structural size ranges from 0.2 nm to 2.4 nm.

[0009] In one embodiment, the composite material grows in-situ on nickel foam.

[0010] In one embodiment, the silver nanowires are interspersed between the pores of the nickel foam, making direct contact with and tightly binding to the NiMnO3 / Ni(OH)2 active material to form a three-dimensional conductive network.

[0011] The present invention also provides a method for preparing the three-dimensional open-pore clustered NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material, and the steps are as follows:

[0012] Step 1, pretreat the nickel foam;

[0013] Step 2, mix an aqueous solution of MnSO4·H2O and an aqueous solution of Ni(NO3)2·6H2O to obtain solution A, and use the silver nanowire dispersion as solution B; the molar ratio of the manganese and nickel raw materials is 2:1 to 1:3;

[0014] Step 3, fully stir solutions A and B until they are uniformly dissolved to obtain a mixed solution;

[0015] Step 4, put the mixed solution and the nickel foam pretreated in Step 1 into an autoclave, carry out a hydrothermal reaction at 160°C to 180°C for 8 to 10 hours, and then naturally cool to room temperature;

[0016] Step 5, collect and centrifuge the product obtained in Step 4, wash it several times with deionized water and ethanol, and then dry it at 90°C to 110°C for 2 hours to obtain the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material.

[0017] In one embodiment, in step 1, nickel foam is ultrasonically cleaned successively with acetone, dilute hydrochloric acid, deionized water, and ethanol, and dried at 60°C to 80°C for 10 to 12 hours; in step 2, the concentration of MnSO4·H2O in the mixed solution is 0.02M to 0.05M; and the molar ratio of nickel and manganese raw materials is 2:1 to 1:3.

[0018] The NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material of the present invention can be used to assemble an asymmetric supercapacitor with outstanding electrochemical performance, increasing ion transport and specific capacitance to improve the inherent defect of low energy density of the capacitor. In one embodiment, an ASC asymmetric supercapacitor device is constructed with the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material as the positive electrode and the AC electrode as the negative electrode.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. By adding an appropriate amount of silver nanowire suspension to the NiMnO3 / Ni(OH)2 composite electrode material, the microscopic morphology of the material is effectively regulated. The nanosheets grow longitudinally under the action of Ag NWs, guiding the nanoflower-like structure of NiMnO3 / Ni(OH)2 to transform into a cluster-like structure with larger open pores; and the NiMnO3 / Ni(OH)2 / Ag NWs composite material is in-situ grown on nickel foam. Since nickel foam participates in the reaction, the obtained composite material is tightly combined with the surface of nickel foam and has a more dispersed morphology. This morphological structure provides more exposed active sites, thereby improving the capacitive behavior of the material.

[0021] 2. Silver nanowires are interspersed between the pores of nickel foam and are in direct contact with the NiMnO3 / Ni(OH)2 active material. And because silver nanowires guide the growth of NiMnO3 / Ni(OH)2, the silver nanowires can be tightly combined with the NiMnO3 / Ni(OH)2 active material, forming an effective three-dimensional conductive network. Therefore, the distance of electron transfer is shortened, and as a one-dimensional metal nanomaterial, silver nanowires themselves have extremely high conductivity, further accelerating the speed of electron transport and enhancing the conductivity of the composite material; at the same time, the in-situ growth of the NiMnO3 / Ni(OH)2 active material on nickel foam without using a binder also improves electron transfer to a certain extent. It is the above two aspects that enable NiMnO3 / Ni(OH)2 / Ag NWs to achieve efficient electron and ion transport, promoting electron transfer at the electrolyte / electrode interface, so that the specific capacitance is effectively improved; the tight connection between silver nanowires, NiMnO3, and Ni(OH)2 greatly reduces the electron transport barrier, and the charge transfer between NiMnO3 / Ni(OH)2 / Ag NWs and the formation of defect and distortion sites also greatly enhance the site activity.

[0022] 3. The preparation process of the present invention is simple. The NiMnO3 / Ni(OH)2 / Ag NWs composite material forms a three-dimensional cluster structure, exposing more active sites and facilitating rapid ion transfer. Silver nanowires interspersed within the pores of nickel foam guide the growth of NiMnO3 / Ni(OH)2 and closely bond with it, forming an effective three-dimensional conductive network. This further facilitates the NiMnO3 / Ni(OH)2 / Ag NWs composite material to simultaneously combine the high potential window of the oxide, the high specific capacitance of the hydroxide, and the high conductivity of the nanowires without the use of a binder. The close connection between each component and the nickel foam enables rapid electron transfer. It is precisely under these multiple effects that the electrochemical performance of the electrode material is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the XRD pattern of the NiMnO3 / Ni(OH)2 / Ag NWs composite material prepared by the present invention.

[0024] Figure 2 This is an SEM image of the NiMnO3 / Ni(OH)2 / Ag NWs composite material prepared by the present invention, wherein Figure (b) is a partial enlargement of Figure (a). DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings and examples. The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0026] The three-dimensional open-pore cluster structure composite electrode material NiMnO3 / Ni(OH)2 / Ag NWs of the present invention has a structure in which nanosheets are the main units. The nanosheets grow in an interlaced manner to form a larger three-dimensional open-pore cluster structure, which shortens the distance of ion transfer and promotes electron transfer at the electrolyte / electrode interface. Some nanosheets in the material are accumulated and attached to silver nanowires, providing more active sites and improving the capacitance characteristics of the electrode material.

[0027] Specifically, the present invention grows in-situ on nickel foam. The addition of nickel foam enables the electrode material to be tightly bonded to the surface of nickel foam. The morphology of the electrode material forms a cluster structure with larger open pores under the guidance of silver nanowires. At the same time, the silver nanowires are interspersed between the pores of nickel foam and are in direct contact with the NiMnO3 / Ni(OH)2 active material to form a conductive network, shortening the electron transfer distance, and its high conductivity further accelerates the electron transfer speed. The tight connection and interaction of each phase of this composite electrode material combine the high potential window of the oxide and the excellent specific capacitance of the hydroxide. The fast electron transfer, fast ion transfer, and synergistic action of more active sites exhibited by the material improve the electrochemical performance of the asymmetric supercapacitor.

[0028] Its preparation specifically may include the following steps:

[0029] Step 1: Ultrasonically clean nickel foam successively with acetone, dilute hydrochloric acid, deionized water, and ethanol, and dry it at 60°C - 80°C for 10 - 12 hours;

[0030] Step 2: Mix 30 mL of an aqueous solution of MnSO4·H2O with a certain concentration and an aqueous solution of Ni(NO3)2·6H2O to obtain solution A, and a dispersion of silver nanowires with a certain molar amount as solution B, where the raw material concentration of MnSO4·H2O is 0.02 M - 0.05 M; the molar ratio of manganese to nickel raw materials is 2:1 - 1:3;

[0031] Step 3: Stir solutions A and B thoroughly until they are dissolved evenly, mix them, and then stir evenly to obtain a mixed solution;

[0032] Step 4: Put the mixed solution and the treated nickel foam into a stainless-steel autoclave with a polytetrafluoroethylene liner, carry out a hydrothermal reaction at 160°C - 180°C for 8 - 10 hours, and then naturally cool to room temperature;

[0033] Step 5: Collect and centrifuge the obtained product, wash it several times with deionized water and ethanol, and then dry it at 90°C - 110°C for 2 hours to obtain the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material.

[0034] The following are several embodiments of the present invention.

[0035] Example 1

[0036] (1) At room temperature of 25°C, add MnSO4·H2O and Ni(NO3)2·6H2O raw materials in a molar ratio of 1:2 to 30 ml of deionized water and mix them, and stir evenly at a constant temperature;

[0037] (2) Add 0.3 mmol of the silver nanowire dispersion to the mixed solution;

[0038] (3) The mixed solution and the treated nickel foam are placed in a stainless-steel autoclave with a PTFE liner, and hydrothermal reaction is carried out at 160 °C for 8 hours, and then it is naturally cooled to room temperature;

[0039] (4) The obtained product is collected by centrifugation, washed three times with deionized water and ethanol respectively, and then dried at 90 °C for 2 hours to obtain the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material.

[0040] From Figure 1 and Figure 2 It can be seen that the successful preparation of the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material has obtained a three-dimensional open-pore cluster structure with larger size and silver nanowires interpenetrate in the pores of nickel foam to guide the growth of nanosheets.

[0041] Example 2

[0042] (1) At room temperature of 25 °C, 30 mL of 0.05 M MnSO4·H2O aqueous solution is mixed with 0.1 M Ni(NO3)2·6H2O aqueous solution, and stirred evenly at a constant temperature;

[0043] (2) 0.6 mmol of silver nanowire dispersion is added to the mixed solution;

[0044] (3) The mixed solution and the treated nickel foam are placed in a stainless-steel autoclave with a PTFE liner, and hydrothermal reaction is carried out at 180 °C for 10 hours, and then it is naturally cooled to room temperature;

[0045] (4) The obtained product is collected by centrifugation, washed three times with deionized water and ethanol respectively, and then dried at 110 °C for 2 hours to obtain the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material.

[0046] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any changes, substitutions, combinations, simplifications, etc. made based on the principle or spirit essence of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for preparing a three-dimensional open-pore clustered NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material, wherein the structure of the three-dimensional open-pore clustered NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material comprises Ni(OH)2 nanosheets as the main unit, which grow in an interlaced manner along fixed crystal planes under the guidance of silver nanowires to form a three-dimensional open-pore clustered structure; and some nanosheets are deposited and attached to the silver nanowires, characterized in that: The steps of the preparation method are as follows: Step 1, pre-treat the nickel foam; Step 2, mix the aqueous solution of MnSO4·H2O and the aqueous solution of Ni(NO3)2•6H2O to obtain solution A, and use the silver nanowire dispersion as solution B; The molar ratio of the manganese and nickel raw materials is 2:1 to 1:3; Step 3, fully stir solution A and solution B until they are evenly dissolved to obtain a mixed solution; Step 4, put the mixed solution and the nickel foam pre-treated in Step 1 into an autoclave, carry out hydrothermal reaction at 160 °C to 180 °C for 8 to 10 hours, and then naturally cool to room temperature; Step 5, collect and centrifuge the product obtained in Step 4, wash it several times with deionized water and ethanol, and then dry it at 90 °C to 110 °C for 2 hours to obtain the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material.

2. The preparation method of the three-dimensional porous cluster-like NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material according to claim 1, characterized in that, The width range of the Ni(OH)2 nanosheets is 0.3 nm - 3.8 nm.

3. The preparation method of the three-dimensional porous cluster-like NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material according to claim 1 or 2, characterized in that, The diameter of the silver nanowires is about 0.6 nm - 2.2 nm.

4. The preparation method of the three-dimensional porous cluster-like NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material according to claim 1, characterized in that, For the three-dimensional open-pore cluster structure, three-dimensional refers to the three-dimensional spatial structure, open-pore means the pore structure appearing in the composite material, and cluster means the accumulation manifestation of the pore structure of the composite material. Its structure size range is 0.2 nm - 2.4 nm.

5. The preparation method of the three-dimensional porous cluster-like NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material according to claim 1, characterized in that, The composite electrode material grows in-situ on the nickel foam.

6. The preparation method of the three-dimensional open-pore cluster-like NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material according to claim 5, characterized in that, The silver nanowires are inserted between the pores of the nickel foam, directly contact and tightly combine with the NiMnO3 / Ni(OH)2 active material to form a three-dimensional conductive network.

7. The preparation method of the three-dimensional open-pore cluster-like NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material according to claim 1, characterized in that, In Step 1, ultrasonically clean the nickel foam in turn with acetone, dilute hydrochloric acid, deionized water, and ethanol, and dry it at 60 °C to 80 °C for 10 to 12 hours; in Step 2, the concentration of the MnSO4·H2O raw material is 0.02 M to 0.05 M.

8. Application of the preparation method of the three-dimensional open-pore cluster NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material described in Claim 1 for assembling an asymmetric supercapacitor.

9. The application according to claim 8, characterized in that Using the NiMnO3 / Ni(OH)2 / Ag NWs composite electrode material as the positive electrode and the AC electrode as the negative electrode, an ASC asymmetric supercapacitor device was constructed.

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