Preparation method of zinc negative electrode with copper-doped carbon fiber interface modification layer

Abstract

The invention relates to a carbon nanofiber loaded Cu nanoparticle composite material prepared by combining an electrostatic spinning method and a high-temperature in-situ reduction reaction and used as a high-cycle-stability zinc negative electrode coating of an aqueous zinc ion battery. Belongs to the technical field of new energy materials. The prepared composite electrode material is regular in structure and excellent in electrochemical performance. Cu is introduced through a high-temperature in-situ reduction reaction. And after the Cu is loaded with the carbon nanofibers, not only is the slow dynamic process of the bare zinc electrode improved, but also the uniform deposition of Zn < 2 + > on the zinc negative electrode in the embedding / separating process is induced.

Description

[0001] The present invention belongs to the technical field of new energy materials, and relates to a method of combining an electrostatic spinning method with a high-temperature in-situ reduction reaction to prepare a carbon nanofiber-loaded Cu nanoparticle composite with a zinc negative electrode as a high-stability cyclic electrode material. Background Art

[0002] After the Industrial Revolution, the industrial production and technological development of society have been greatly dependent on the use of traditional fossil energy to a certain extent. Nowadays, in order to alleviate the crisis of fossil energy depletion caused by excessive exploitation of fossil energy, and with the transformation of the global energy structure, the large-scale application of new energy (such as wind energy and solar energy) has put forward higher requirements for energy storage technology. Lithium-ion batteries (LIBs) occupy the vast majority of the market due to their high energy density, but due to their low natural reserves, they are prone to combustion and even explosion, which limits their further use. Therefore, the exploration of low-cost and high-safety energy storage technology is imminent. Aqueous zinc-ion batteries (AZIBs) are a rechargeable and dischargeable battery based on aqueous electrolytes. They have the advantages of high safety, low cost, and environmental friendliness. They are one of the important research directions of current new energy storage technology. However, the formation of zinc dendrites and interfacial side reactions during the cycle of AZIBs limit their further development. During the zinc deposition process, uneven nucleation leads to uneven electric field at the negative electrode interface, which leads to the formation of zinc dendrites. At the same time, zinc ions will preferentially deposit on the adsorption sites that have been deposited, which will cause the dendrites to grow and then pierce the diaphragm to cause the battery to short-circuit. Since the theoretical electrode potential of zinc (-0.76 V) is lower than that of water (pH: 5-7, -0.29 V to -0.41 V), this inevitably triggers hydrogen evolution reaction, passivation, and corrosion side reactions, thereby reducing the cycle life of AZIBs.

[0003] At present, there are some studies on improving the adsorption sites on the surface of zinc negative electrode to induce uniform deposition of zinc ions and using surface engineering technologies such as inorganic / organic coatings to modify zinc sheets to solve the above problems. For example, Wang et al. (Wang, Xu, et al. "A surface engineering strategy for the stabilization of zinc metalanodes with montmorillonite layers toward long-life rechargeable aqueous zincion batteries" Journal of Energy Chemistry 100 (2025) 94–105.) used surface engineering technology to coat the surface of zinc sheets with montmorillonite coating (MMT). MMT can be used for Zn 2+It provides an ordered migration channel for the migration of zinc and is beneficial to its reaction kinetics. Su et al. (Tzu-Chi Su, et al "3Dporous reduced graphene oxide-coatedzinc anodes for highly-stable aqueous zinc-ion capacitors via electrostaticspray deposition" Carbon 229 (2024) 119467) prepared a three-dimensional porous reduced graphene oxide coating Zn (rGO@Zn) by electrostatic spray deposition (ESD) technology and used it as the negative electrode of aqueous hybrid zinc ion capacitors (ZICs). The conductive reduced graphene oxide on the surface of the zinc negative electrode stabilizes the electric field during the stripping / galvanizing process, and the functional groups guide the Zn 2+ The deposition sites make zinc deposition uniform during the cycle and improve the electrochemical performance.

[0004] In order to further improve the electrochemical performance of zinc anode, we proposed a method of preparing carbon nanofiber-loaded Cu nanoparticle composites as high cycle stability zinc anode coatings by combining electrospinning and high-temperature in-situ reduction reaction. Polyacrylonitrile (PAN) was used as the spinning solution base liquid and as the carbon source of carbon nanofibers (CNFs). Cu(CH3COO)2·H2O was used as the Cu source. Cu(CH3COO)2·H2O was dissolved in polyacrylonitrile / N,N-dimethylformamide (PAN / DMF) solution to prepare a mixed spinning solution, which was sprayed on the surface of bare zinc anode by electrospinning technology as a zinc anode protective coating with high electrochemical activity and high cycle stability. The Cu-CNFs / Zn composite electrode was obtained by high-temperature annealing. During the high-temperature annealing process, the PAN-based composite nanofibers were transformed into carbon nanofibers, and Cu was generated in situ. The Cu element was successfully introduced to prepare Cu-doped carbon nanofibers, and Cu was evenly dispersed in the carbon nanofibers in the form of nanoparticles. The CNFs prepared by electrospinning have the advantages of high aspect ratio and large surface area. At the same time, copper is one of the most conductive metals in nature, second only to silver, and the 3d electron shell of copper is almost fully filled, and 4s electrons are the main contributor to its conductivity. Cu doping can significantly improve the material stability and electronic conductivity of CNFs. In the electrospinning process, zinc sheets are used as nanofiber collection plates, and Cu-CNFs with a high aspect ratio are electrostatically sprayed on the zinc sheets. The zinc sheets covered with nanofibers are subsequently stabilized and annealed at high temperature to prepare binder-free Cu-CNFs / Zn composite electrode materials. This component structure significantly improves the ion transfer efficiency and conductivity, while inducing Zn 2+During the insertion / extraction, Cu-CNFs are uniformly deposited on the surface of the zinc negative electrode, and Cu-CNFs form a very dense film, which reduces the direct contact between the electrolyte and the zinc negative electrode and weakens the corrosion of the zinc negative electrode. The prepared Cu-CNFs / Zn composite electrode material has a high conductivity at 1A g -1 After 300 cycles, the current density reaches 350 mAh g -1 The results show that the present invention has a high reversible specific capacity and exhibits better cycle stability and cycle life than the comparative example. Summary of the invention

[0005] Carbon nanofibers loaded with Cu nanoparticles are composited with zinc negative electrode to form a high-stability cyclic electrode material. The fiber morphology and component ratio are controlled by adjusting the spinning solution ratio and the working parameters during the electrospinning process.

[0006] The specific steps are as follows:

[0007] (1) Add 0.03-0.08 g of Cu(CH3COO)2·H2O to 2 ml of DMF and sonicate for 1 h to fully dissolve it. Add 0.07-0.13 g of PAN and then 0.9 ml of DMF. Stir magnetically for 12 h until a viscous spinning solution is obtained.

[0008] (2) Add the above spinning solution into a 5 ml syringe and use a 20 g needle as the spinning needle. Set the spinning voltage to -1 to 15 kV and the spinning speed to 0.083 mm min. -1 is the injection speed, 200 mm min -1 Spinning is carried out at a translation speed of .

[0009] (3) The zinc foil coated with the polymer-based nanofiber coating obtained after spinning was heated in a tube furnace at 1°C min in an air atmosphere. -1 The temperature was raised to 200 °C at a rate of 2 °C min-1 and kept at that temperature for 7 h to obtain the pre-oxidized composite electrode material. -1 The temperature was raised to 300-600°C at a heating rate and kept for 3 h to obtain Cu-CNFs / Zn electrode material.

[0010] According to the present invention, preferably, the optimal addition amount of Cu(CH3COO)2·H2O in step (1) is 0.05 g.

[0011] According to the present invention, preferably, the optimal amount of PAN added in step (1) is 0.1 g

[0012] According to the present invention, preferably, the optimal spinning voltage in step (2) is 15 kV.

[0013] According to the present invention, preferably, the optimal carbonization temperature in step (3) is 480°C.

[0014] Description of the attached drawings and tables

[0015] Figure 1 This is the X-ray diffraction pattern of the Cu-CNFs / Zn series electrode material prepared in Example 1 of the present invention.

[0016] Figure 2 This is a scanning electron microscope image of the Cu-CNFs / Zn series electrode material prepared in Example 1 of the present invention.

[0017] Figure 3 The electrochemical performance diagram of the Cu-CNFs / Zn series electrode material prepared in Example 1 of the present invention and the electrochemical performance diagram of the bare Zn electrode material prepared in the comparative example. DETAILED DESCRIPTION

[0018] The present invention is further described below with reference to specific examples and drawings, but is not limited thereto. Meanwhile, the experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0019] Embodiment 1:

[0020] 0.05g of Cu(CH3COO)2·H2O was added to 2ml of DMF and ultrasonicated for 1h; then 0.1g of PAN and 0.09ml of DMF were added and magnetically stirred for 12 hours to obtain a viscous spinning solution. The viscous spinning solution was loaded into a 5ml syringe and a 20g needle was used as the spinning needle. The spinning voltage was -1 to 15kV and the spinning speed was 0.083mm min. -1 Injection speed, 200 mm min -1 Spinning is carried out at a translation speed of .

[0021] The zinc foil coated with the polymer-based nanofiber coating obtained after spinning was heated in a tube furnace at 1 °C min -1 The temperature was raised to 200 °C at a rate of 2 °C min-1 and kept at that temperature for 7 h to obtain the pre-oxidized composite electrode material. -1 The temperature was raised to 300-600°C at a heating rate and kept for 3 h to obtain Cu-CNFs / Zn electrode material.

[0022] Embodiment 2:

[0023] 0.05g of Cu(CH3COO)2·H2O was added to 2ml of DMF and ultrasonicated for 1h; then 0.09g of PAN and 0.09ml of DMF were added and magnetically stirred for 12 hours to obtain a viscous spinning solution. The viscous spinning solution was loaded into a 5ml syringe and a 20g needle was used as the spinning needle. The spinning voltage was -1 to 15kV and the spinning speed was 0.083mm min. -1 Injection speed, 200mmmin -1 Spinning is carried out at a translation speed of .

[0024] The zinc foil coated with the polymer-based nanofiber coating obtained after spinning was heated in a tube furnace at 1 °C min -1 The temperature was raised to 200 °C at a rate of 2 °C min-1 and kept at that temperature for 7 h to obtain the pre-oxidized composite electrode material. -1 The temperature was raised to 300-600°C at a heating rate and kept for 3 h to obtain Cu-CNFs / Zn electrode material.

[0025] Embodiment 3:

[0026] 0.05g of Cu(CH3COO)2·H2O was added to 2ml of DMF and ultrasonicated for 1h; then 0.08g of PAN and 0.09ml of DMF were added and magnetically stirred for 12 hours to obtain a viscous spinning solution. The viscous spinning solution was loaded into a 5ml syringe and a 20g needle was used as the spinning needle. The spinning voltage was -1 to 15kV and the spinning speed was 0.083mm min. -1 Injection speed, 200mmmin -1 Spinning is carried out at a translation speed of .

[0027] The zinc foil coated with the polymer-based nanofiber coating obtained after spinning was heated in a tube furnace at 1 °C min -1 The temperature was raised to 200 °C at a rate of 2 °C min-1 and kept at that temperature for 7 h to obtain the pre-oxidized composite electrode material. -1 The temperature was raised to 300-600°C at a heating rate and kept for 3 h to obtain Cu-CNFs / Zn electrode material.

[0028] Comparative Example:

[0029] The bare zinc foil was heated in a tube furnace at 1°C min -1 The temperature was raised to 200 °C at a rate of 1.5 °C and kept at this temperature for 7 h. The zinc foil was then heated at 2 °C min-1 in an argon-hydrogen atmosphere. -1 The temperature was raised to 480°C at a heating rate of and kept for 3 h to obtain the Zn electrode material.

Claims

1. Carbon nanofiber-loaded Cu nanoparticle composite material as high cycle stability zinc negative electrode coating, characterized in that: The fiber morphology and component ratio are controlled by adjusting the spinning solution ratio and the working parameters during the electrospinning process; The specific steps are as follows: (1) Add 0.03-0.08 g of Cu(CH3COO)2·H2O to 2 ml of DMF and sonicate for 1 h to fully dissolve it, add 0.07-0.13 g of PAN, and then add 0.9 ml of DMF; stir magnetically for 12 h until a viscous spinning solution is obtained; (2) Add the above spinning solution into a 5 ml syringe and use a 20 g needle as the spinning needle. Set the spinning voltage to -1 to 15 kV and the spinning speed to 0.083 mm min. -1 Injection speed, 200 mm / min -1 Spinning is carried out at a translation speed of (3) The zinc foil coated with the polymer-based nanofiber coating obtained after spinning was heated in a tube furnace at 1°C min in an air atmosphere. -1 The temperature was raised to 200 °C at a rate of 1.5 °C and kept at this temperature for 7 h to obtain the pre-oxidized composite electrode material. -1 The temperature was raised to 300-600°C at a heating rate and kept for 3 h to obtain Cu-CNFs / Zn electrode material.

2. The carbon nanofiber-supported Cu nanoparticle composite material according to claim 1 is used as a zinc negative electrode coating with high cycle stability, characterized in that: The optimal addition amount of Cu(CH3COO)2·H2O in step (1) is 0.05g.

3. The carbon nanofiber-supported Cu nanoparticle composite material as a high cycle stability zinc negative electrode coating according to claim 1, characterized in that: The optimal amount of PAN added in step (1) is 0.1 g.

4. The carbon nanofiber-supported Cu nanoparticle composite material as a high cycle stability zinc negative electrode coating according to claim 1, characterized in that: The optimal spinning voltage in step (2) is 15 kV.

5. The carbon nanofiber-supported Cu nanoparticle composite material as a high cycle stability zinc negative electrode coating according to claim 1, characterized in that: The optimum carbonization temperature in step (3) is 480°C.

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