Porous CuO layered nanostructured electrode materials and their preparation methods

Abstract

This invention discloses a porous CuO layered nanostructured electrode material and its preparation method, comprising the following steps: 1) Copper nitrate trihydrate and terephthalic acid are sequentially added to dimethylformamide (DMF) and stirred to dissolve, obtaining a sky-blue solution; 2) The sky-blue solution is transferred to a reaction vessel and subjected to hydrothermal reaction in an oven, cooled, washed with alcohol, and dried to finally obtain the electrode material. The beneficial effects of this invention are: the porous CuO layered nanostructured electrode material and its preparation method prepared by hydrothermal reaction exhibit high capacity, high power, and good cycle stability when used as a negative electrode material for lithium-ion batteries; the process is simple, the reaction conditions are mild, it is easy to scale up, and it meets the requirements of green chemistry.

Description

Technical Field

[0001] This invention relates to the fields of nanomaterials and electrochemical technology, and particularly to porous CuO layered nanostructured electrode materials and their preparation methods. Background Technology

[0002] Today, lithium-ion batteries are increasingly used in pure electric vehicles and hybrid electric vehicles. Developing high-capacity, high-power, long-cycle-life, and low-cost lithium-ion batteries is urgently needed. CuO, a member of the transition metal oxide family, has great potential to replace traditional carbon-based anode material graphite (theoretical specific capacity of 372 mAh / g), boasting a theoretical specific capacity as high as 674 mAh / g. It also exhibits excellent performance characteristics such as safety, environmental friendliness, and low cost. However, CuO undergoes volume expansion during charge and discharge, leading to structural damage and limiting its application. How to apply CuO to lithium batteries is a problem that needs to be solved at this stage. To address these issues, a solution is proposed below. Summary of the Invention

[0003] The purpose of this invention is to provide porous CuO layered nanostructured electrode materials and their preparation methods, which have the advantages of simple process, compliance with the requirements of green chemistry, high surface area and lithium ion attachment sites and high capacity, and good electrochemical performance.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0005] A porous CuO layered nanostructured electrode material and its preparation method are disclosed. The electrode material comprises a two-dimensional material formed by the oriented overlapping of CuO nano-subunits, stacked longitudinally to form a bulk structure. The preparation of the electrode material includes the following steps:

[0006] S1: Copper nitrate trihydrate and terephthalic acid were added sequentially to dimethylformamide (DMF), stirred and dissolved to obtain a sky-blue solution;

[0007] S2: The sky-blue solution was transferred to a reaction vessel and subjected to a hydrothermal reaction in an oven. After the reaction was completed, the solution was cooled, washed with alcohol, and then dried to obtain the precursor terephthalic copper.

[0008] S3: The precursor is placed in a muffle furnace and the electrode material is obtained by sintering in an air atmosphere.

[0009] Preferably, in step S1, the amount of trihydrate and copper nitrate is 0.2-1g, the amount of terephthalic acid is 1-2g, and the amount of dimethylformamide is 80ml.

[0010] Preferably, the temperature of the hydrothermal reaction in step S2 is 140-200℃, and the time of the hydrothermal reaction is 4-24h.

[0011] Preferably, the sintering temperature in step S3 is: first pre-fired at 160℃ for 1-2 hours, and then sintered at 300-400℃ for 2-4 hours, with a heating rate of 10℃ / min.

[0012] Preferably, the porous CuO layered nanostructure electrode material is used as the negative electrode active material of a lithium-ion battery.

[0013] The beneficial effects of this invention are as follows: This invention uses a metal-organic framework formed by hydrothermal synthesis of copper nitrate trihydrate and terephthalic acid as a template, and sintersects it in air to obtain a porous layered structure. Due to its small particle size and interlayer porosity, it can play a good buffering role during charge-discharge volume expansion, reducing capacity decay and improving cycle stability. Simultaneously, the particle size of approximately 20 nanometers provides a large specific surface area and surface energy, offering more lithium-ion attachment sites and increasing capacity. This invention mainly prepares porous CuO layered nanostructured electrode materials through hydrothermal synthesis and air sintering. When used as a negative electrode material for lithium-ion batteries, it exhibits high capacity and good cycle stability. This invention is highly feasible, easily scaled up, conforms to the characteristics of green chemistry, and can be used for market promotion. Attached Figure Description

[0014] Figure 1 This is a SEM image of the porous CuO layered nanostructure electrode material from Example 1.

[0015] Figure 2 This is a TEM image of the porous CuO layered nanostructure electrode material from Example 1.

[0016] Figure 3 The image shows the XRD pattern of the porous CuO layered nanostructure electrode material in Example 1.

[0017] Figure 4 The battery rate diagram for the porous CuO layered nanostructure electrode material in Example 1 is shown.

[0018] Figure 5 The graph shows the battery cycle performance of the porous CuO layered nanostructure electrode material in Example 1 at a current density of 100 mA / g.

[0019] Figure 6 The graph shows the battery cycle performance of the porous CuO layered nanostructure electrode material in Example 1 at a current density of 2 A / g.

[0020] Figure 7The graph shows the battery cycle performance of the porous CuO layered nanostructure electrode material in Example 1 at a current density of 5 A / g. Detailed Implementation

[0021] The following description is only a preferred embodiment of the present invention, and the scope of protection is not limited to this embodiment. Any technical solution that falls within the scope of the present invention should be protected by the present invention.

[0022] Example 1

[0023] A method for preparing porous CuO layered nanostructured electrode materials includes the following steps:

[0024] 1) Add 0.3g of copper nitrate and 1.313g of terephthalic acid to dimethylformamide and stir to dissolve, resulting in a light blue solution.

[0025] 2) The light blue solution was transferred to a reaction vessel and heated in a 140°C oven for 6 hours. After cooling, it was washed three times with alcohol and dried to obtain a blue powder, copper terephthalate precursor.

[0026] 3) Transfer terephthalic copper into a crucible and heat it in a muffle furnace at 160°C for 2 hours. Then heat it to 350°C and heat it for 2 hours. After cooling, the final product, porous CuO layered nanostructure electrode material, is obtained. Each layer of the porous CuO layered nanostructure electrode material is composed of CuO particles with a particle size of 15-25 nm.

[0027] As attached Figure 1 The SEM image shown reveals a porous CuO layered nanostructure; (Attached) Figure 2 The TEM images show that each layer is composed of CuO particles with a particle size of 15-25 nm.

[0028] This embodiment uses a porous CuO layered nanostructure electrode material as an example; its structure was determined by X-ray diffraction. (See attached image.) Figure 3 The X-ray diffraction (XRD) pattern shown indicates that the porous CuO layered nanostructure electrode material is in good agreement with the CuO spectral lines.

[0029] The application of the porous CuO layered nanostructure obtained in this embodiment as the negative electrode active material of lithium-ion battery is as follows: In the fabrication process of the negative electrode sheet, porous CuO layered nanostructure is used as the active material, acetylene black is used as the conductive agent, and sodium alginate is used as the coagulant. The mass ratio of active material, acetylene black and sodium alginate is 7:2:1. After they are fully mixed in the proportion, they are coated on copper foil and punched into a disc. The punched electrode sheet is placed in an oven at 80°C and dried for 24 hours before use.

[0030] A coin-type lithium-ion battery was assembled using 1 M LiPF6 dissolved in ethylene carbonate (EC) and dimethyl carbonate (DMC) as the electrolyte, lithium foil as the positive electrode, Celgard 2325 as the separator, and CR2016 stainless steel as the battery casing. The preparation method and remaining steps of the lithium-ion battery are the same as those of conventional preparation methods.

[0031] Appendix Figure 4 As shown, at current densities of 100 mAh / g, 100 mA / g, 200 mA / g, 500 mAh / g, 1000 mA / g, 2000 mA / g, 5000 mA / g, and 10000 mA / g, the initial discharge specific capacity of the porous CuO layered nanostructure electrode material can reach 682.9 mAh / g, 539.2 mAh / g, 474.9 mAh / g, 400.2 mAh / g, 345.0 mAh / g, 266.7 mAh / g, and 185.3 mAh / g, respectively. The material exhibits excellent rate performance; after charging and discharging at different current densities from 100 mAh / g to 1000 mAh / g, the capacity at a current density of 100 mAh / g can recover to 661.0 mAh / g, with a capacity retention rate of 96.79%. This indicates that the material has excellent rate performance.

[0032] Appendix Figure 5 As shown: at a current density of 100 mA / g, the specific capacity of the material during the second cycle was 537.4 mAh / g, and after 100 cycles, the capacity increased to 737.3 mAh / g, with a capacity retention rate of 137.2%.

[0033] Appendix Figure 6 As shown: at a current density of 2 A / g, the specific capacity of the material after the 10th cycle is 294.9 mAh / g, and after 10,000 cycles, the capacity still reaches 199.7 mAh / g, with a capacity retention rate of 67.7%.

[0034] Appendix Figure 7 As shown: at a current density of 5 A / g, the specific capacity of the material after the 10th cycle is 283.5 mAh / g, and after 10,000 cycles, the capacity is still 170.2 mAh / g, with a capacity retention rate of 60.0%.

[0035] Example 2

[0036] 1) Add 0.3g of copper nitrate and 1.313g of terephthalic acid to dimethylformamide and stir to dissolve, thus obtaining a solution.

[0037] 2) The light blue solution was transferred to a reaction vessel and hydrothermally heated in an oven at 140°C for 6 hours. After cooling, it was washed three times with alcohol and dried to obtain a blue powder, copper terephthalate precursor.

[0038] 3) Transfer terephthalic copper into a crucible and heat it in a muffle furnace at 160°C for 2 hours. Then, heat it to 400°C and heat it for 2 hours. After cooling, the final product, porous CuO layered nanostructured electrode material, is obtained.

[0039] Taking the porous CuO layered nanostructure electrode material obtained in this example as an example, at a current density of 100 mA / g, the specific capacity of the porous CuO layered nanostructure electrode material can reach 225.5 mAh / g after the 10th discharge cycle, and the capacity still remains at 156.8 mAh / g after 1000 cycles, with a capacity retention rate of 69.5%.

[0040] Example 3

[0041] 1) Add 0.3g of copper nitrate and 1.313g of terephthalic acid to dimethylformamide and stir to dissolve, thus obtaining a solution.

[0042] The pale blue solution was transferred to a reaction vessel and hydrothermally heated in an oven at 140°C for 6 hours. After cooling, it was washed three times with alcohol and dried to obtain a blue powder, copper terephthalate precursor.

[0043] 2) Transfer terephthalic copper into a crucible and heat it in a muffle furnace at 160°C for 2 hours. Then heat it to 450°C and heat it for 2 hours. After cooling, the final product, porous CuO layered nanostructured electrode material, is obtained.

[0044] 3) Taking the porous CuO layered nanostructure electrode material obtained in this example as an example, at a current density of 100 mA / g, the second discharge specific capacity of the porous CuO layered nanostructure electrode material can reach 342.4 mAh / g, and after 49 cycles, the capacity is 385.4 mAh / g, with a capacity retention rate of 112.6%.

[0045] Example 4

[0046] 1) Add 0.3g of copper nitrate and 1.313g of terephthalic acid to dimethylformamide and stir to dissolve, thus obtaining a solution.

[0047] 2) The light blue solution was transferred to a reaction vessel and heated in a 140°C oven for 10 hours. After cooling, it was washed three times with alcohol and dried to obtain a blue powder, copper terephthalate precursor.

[0048] 3) Transfer terephthalic copper into a crucible and heat it in a muffle furnace at 160°C for 2 hours. Then heat it to 350°C and heat it for 2 hours. After cooling, the final product, porous CuO layered nanostructure electrode material, is obtained.

[0049] Taking the porous CuO layered nanostructure electrode material obtained in this example as an example, at a current density of 100 mA / g, the second discharge specific capacity of the porous CuO layered nanostructure electrode material can reach 441.3 mAh / g, and after 100 cycles, the capacity is 634.0, with a capacity retention rate of 143.7%.

[0050] Example 5

[0051] 1) Add 1.3g of copper nitrate and 3.0g of terephthalic acid to dimethylformamide and stir to dissolve, thus obtaining a solution.

[0052] 2) The light blue solution was transferred to a reaction vessel and hydrothermally heated in an oven at 140°C for 6 hours. After cooling, it was washed three times with alcohol and dried to obtain a blue powder, copper terephthalate precursor.

[0053] 3) Transfer terephthalic copper into a crucible and heat it in a muffle furnace at 160°C for 2 hours. Then raise the temperature to 450°C and heat it for 2 hours. After cooling, the final product, porous CuO layered nanostructured electrode material, is obtained.

[0054] Taking the porous CuO layered nanostructure electrode material obtained in this example as an example, at a current density of 200 mA / g, the second discharge specific capacity of the porous CuO layered nanostructure electrode material can reach 108.8 mAh / g, and after 100 cycles, the capacity still has 119.8 mAh / g, with a capacity retention rate of 110.1%.

[0055] The specific embodiments described above further illustrate the technical problems, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The application of a porous CuO layered nanostructure electrode material as a negative electrode active material for lithium-ion batteries, characterized in that: The preparation method of porous CuO layered nanostructured electrode material includes the following steps: 1) Add 0.3g of copper nitrate and 1.313g of terephthalic acid to dimethylformamide and stir to dissolve, resulting in a light blue solution; 2) The light blue solution was transferred to a reaction vessel and heated in a 140°C oven for 6 hours. After cooling, it was washed three times with alcohol and dried to obtain a blue powder, copper terephthalate precursor. 3) Transfer terephthalic copper into a crucible and heat it in a muffle furnace at 160°C for 2 hours. Then heat it to 350°C and heat it for 2 hours. After cooling, the final product, porous CuO layered nanostructure electrode material, is obtained. Each layer of the porous CuO layered nanostructure electrode material is composed of CuO particles with a particle size of 15-25 nm.

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