Iron oxide / carbon-based composite negative electrode material and preparation method and application thereof

Abstract

The invention discloses an iron oxide / carbon-based composite negative electrode material as well as a preparation method and application thereof, and belongs to the technical field of battery materials. The preparation method comprises the following steps: putting a carbon material and iron oxide powder into a ball-milling tank for ball-milling, and after ball-milling, performing ultrasonic treatment and drying on the mixture to obtain the iron oxide / carbon-based composite negative electrode material. The prepared iron oxide / carbon-based composite negative electrode material can greatly improve the charge and discharge performance of a lithium battery and prolong the cycle life of the lithium battery, through a high-speed ball milling and ultrasonic dispersion mixing technology, uniform compounding of a carbon material and iron oxide at the nanoscale is achieved, and under the 2C multiplying power, the discharge capacity retention ratio can be increased to 70%-80%, and the cycle index can reach 1000-1200 times.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to an iron oxide / carbon-based composite anode material, its preparation method, and its application. Background Technology

[0002] With the rapid development of modern technology, the demand for high-performance lithium batteries is increasing in fields such as portable electronic devices, electric vehicles, and energy storage systems. Lithium batteries, due to their high energy density, long cycle life, and lack of memory effect, have become one of the most promising rechargeable batteries. Among these, the negative electrode material, as a key component of lithium batteries, plays a crucial role in the overall performance of the battery.

[0003] Currently, commercially available lithium-ion battery anode materials are mainly graphite. Graphite has advantages such as low cost, structural stability, and low lithium intercalation potential, but its theoretical specific capacity is only 372 mAh / g, which is insufficient to meet the future development needs of high-energy-density lithium-ion batteries. To improve the energy density and overall performance of lithium-ion batteries, researchers have been continuously exploring and developing new anode materials.

[0004] Iron oxide, as a potential high-capacity anode material, has attracted widespread attention due to its high theoretical specific capacity, abundant resources, low cost, and environmental friendliness. However, iron oxide suffers from severe volume expansion during charge and discharge, leading to pulverization and spalling of the electrode material, which in turn causes a sharp decline in battery cycle performance. Furthermore, the poor electronic conductivity of iron oxide also limits its practical application in lithium-ion batteries.

[0005] To address the challenges of using iron oxide as an anode material, researchers have attempted to composite it with other materials. For example, some studies have involved simple mixing of iron oxide with carbon materials, hoping to leverage the high conductivity and good mechanical properties of carbon to improve the performance of iron oxide. However, this simple composite method suffers from poor composite effect and weak synergy, failing to effectively control the composite structure and interface quality of carbon and iron oxide at the nanoscale.

[0006] Therefore, developing a composite method that can effectively improve the performance of iron oxide anode materials and prepare high-performance lithium battery composite anode materials has become a key issue that urgently needs to be addressed in the current lithium battery field. Summary of the Invention

[0007] The first technical problem to be solved by this invention is to provide an iron oxide / carbon-based composite anode material with excellent charge-discharge performance and cycle life. The second technical problem to be solved by this invention is to provide a method for preparing the iron oxide / carbon-based composite anode material, which achieves uniform composite of carbon materials and iron oxide at the nanoscale through high-speed ball milling combined with ultrasonic dispersion and mixing process. The third technical problem to be solved by this invention is to provide the application of this composite anode material in lithium battery anode sheets.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing an iron oxide / carbon-based composite anode material involves placing carbon material and iron oxide powder into a ball mill jar for ball milling. After ball milling, the mixture is subjected to ultrasonic treatment and dried to obtain the iron oxide / carbon-based composite anode material.

[0010] Furthermore, the carbon material is selected from one of graphite powder, carbon nanotubes, and acetylene black.

[0011] Furthermore, the particle size of the carbon material is 10 nm to 10 μm.

[0012] Furthermore, the ball milling speed is 400~600 rpm / min.

[0013] Furthermore, the ball milling time is 2-4 hours.

[0014] Furthermore, the mass ratio of the carbon material to the iron oxide powder is 1:3~5.

[0015] Furthermore, the ultrasonic power is 300~500 W, and the duration is 1~2 h.

[0016] Furthermore, the iron oxide / carbon-based composite anode material prepared by the aforementioned method is an iron oxide / carbon-based composite anode material.

[0017] Furthermore, the application of the iron oxide / carbon-based composite anode material in lithium battery anode sheets.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The iron oxide / carbon-based composite anode material prepared by the present invention can significantly improve the charge-discharge performance and cycle life of lithium batteries. Through high-speed ball milling combined with ultrasonic dispersion and mixing process, carbon materials and iron oxide are uniformly composited at the nanoscale. At 2C rate, the discharge capacity retention rate can be increased to 70%-80%, and the cycle number can reach 1000-1200 times.

[0020] (2) By adjusting process parameters such as ultrasonic power and ball milling speed, the present invention effectively solves problems such as uneven composite, poor interface bonding and agglomeration of iron oxide particles.

[0021] (3) The present invention uses carbon nanotubes as carbon materials, and the 2C discharge capacity retention rate reaches 78% and the cycle life is 1150 times, showing excellent synergistic effect. Detailed Implementation

[0022] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0023] Example 1

[0024] A method for preparing an iron oxide / carbon-based composite anode material includes the following steps:

[0025] 25 g of graphite powder (particle size 5-10 μm) and 75 g of iron oxide powder were placed in a ball mill jar, and 100 mL of anhydrous ethanol was added. The mixture was ball-milled at 400 rpm / min for 2 h. After ball milling, the mixture was ultrasonically dispersed at 300 W for 2 h. The homogeneous mixture was then vacuum-dried at 80 ℃ for 12 h to obtain the iron oxide / carbon-based composite anode material.

[0026] Example 2

[0027] A method for preparing an iron oxide / carbon-based composite anode material includes the following steps:

[0028] 20 g of carbon nanotubes (particle size 10-20 nm) and 80 g of iron oxide powder were placed in a ball mill jar, and 120 mL of anhydrous ethanol was added. The mixture was ball-milled at 500 rpm / min for 3 h. After ball milling, the mixture was ultrasonically dispersed at 400 W for 1.5 h. The homogeneous mixture was then vacuum-dried at 80 °C for 12 h to obtain the iron oxide / carbon-based composite anode material.

[0029] Example 3

[0030] A method for preparing an iron oxide / carbon-based composite anode material includes the following steps:

[0031] 16.7 g of acetylene black (particle size 2-5 μm) and 83.3 g of iron oxide powder were placed in a ball mill jar, and 150 mL of anhydrous ethanol was added. The mixture was ball-milled at 600 rpm / min for 4 h. After ball milling, the mixture was ultrasonically dispersed at 500 W for 1 h. The homogeneous mixture was then vacuum-dried at 80 °C for 12 h to obtain the iron oxide / carbon-based composite anode material.

[0032] Comparative Example 1

[0033] 25 g of graphite powder (particle size 5-10 μm) and 75 g of iron oxide powder were mixed, and 100 mL of anhydrous ethanol was added. The mixture was stirred at 200 rpm / min for 4 h. The homogeneous mixture was then vacuum dried at 80 °C for 12 h to obtain the iron oxide / carbon-based composite anode material.

[0034] Comparative Example 2

[0035] 20 g of carbon nanotubes (particle size 10-20 nm) and 80 g of iron oxide powder were placed in a ball mill jar, and 120 mL of anhydrous ethanol was added. The mixture was ball-milled at 500 rpm / min for 4.5 h. The homogeneous mixture was then vacuum-dried at 80 °C for 12 h to obtain an iron oxide / carbon-based composite anode material.

[0036] The iron oxide / carbon-based composite anode materials prepared in Examples 1-3 and Comparative Examples 1-2 were used to prepare nickel-iron battery anode sheets. The preparation process was as follows: the iron oxide / carbon-based composite anode material, the conductive agent acetylene black and the binder polytetrafluoroethylene were mixed in a mass ratio of 8:1:1. The paste was evenly coated onto the copper foil current collector. After coating, the sheet was placed in a vacuum drying oven and dried at 80 °C for 6 hours. After drying, the sheet was taken out and allowed to cool naturally. Then, it was rolled on an electric roller press to ensure that there was no breakage.

[0037] The negative electrode shell, lithium metal sheet (negative electrode), separator (polypropylene / polyethylene composite separator), positive electrode sheet with added electrolyte (lithium hexafluorophosphate), gasket, spring and positive electrode shell are stacked in sequence, and then sealed using a button cell sealing machine.

[0038] After the assembled batteries were left to stand for 12 hours, formation testing was performed. The charging current was set to 0.1C, and the charging cutoff voltage to 4.2V. Constant current charging was used, and once the battery voltage reached 4.2V, constant voltage charging was switched until the charging current dropped to 0.05C. After charging, the batteries were left to stand for 1 hour, and then constant current discharge was performed at 0.1C, with a discharge cutoff voltage of 2.75V. The initial charge / discharge capacity and efficiency were recorded. Charge / discharge tests were performed at different rates. At each rate, constant current charging was first performed to 4.2V, followed by constant voltage charging until the current dropped to 0.05C, then left to stand for 1 hour, and finally constant current discharge was performed at the corresponding rate to 2.75V. The discharge capacity at each rate was recorded. Cyclic performance testing: Cyclic test conditions were set, with charge / discharge cycles performed at 1C or 2C current, a charging cutoff voltage of 4.2V, and a discharge cutoff voltage of 2.75V. Multiple cycle tests were performed. The results are shown in Table 1.

[0039] Table 1. Comparison of electrochemical performance between Examples 1-3 and Comparative Examples 1-2

[0040]

[0041] As shown in Table 1, comparing Examples 1-3 and Comparative Examples 1-2, the high-speed ball milling combined with ultrasonic dispersion mixing process adopted in this invention can effectively improve the charge-discharge performance and cycle life of lithium batteries. This is because this process can achieve uniform composite of carbon materials and iron oxide at the nanoscale, optimizing the microstructure of the materials and thus promoting efficient electron and ion transport. In Example 2, carbon nanotubes were used as the carbon material, and their 2C discharge capacity retention rate and cycle life were the best among the three examples, at 78% and 1150 cycles, respectively. This is because carbon nanotubes have a unique one-dimensional nanostructure, good conductivity, and a large specific surface area, which allows them to work better with iron oxide, improving electron transport efficiency and thus enhancing battery performance.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an iron oxide / carbon-based composite anode material, characterized in that, Carbon materials and iron oxide powder are placed in a ball mill jar for ball milling. After ball milling, the mixture is ultrasonically treated and dried to obtain an iron oxide / carbon-based composite anode material.

2. The method for preparing the iron oxide / carbon-based composite anode material according to claim 1, characterized in that: The carbon material is selected from one of graphite powder, carbon nanotubes, and acetylene black.

3. The method for preparing the iron oxide / carbon-based composite anode material according to claim 1, characterized in that: The particle size of the carbon material is 10 nm to 10 μm.

4. The method for preparing the iron oxide / carbon-based composite anode material according to claim 1, characterized in that: The ball milling speed is 400~600 rpm / min.

5. The method for preparing the iron oxide / carbon-based composite negative electrode material according to claim 1, characterized in that: The ball milling time is 2-4 hours.

6. The method for preparing the iron oxide / carbon-based composite negative electrode material according to claim 1, characterized in that: The mass ratio of the carbon material to the iron oxide powder is 1:3~5.

7. The method for preparing the iron oxide / carbon-based composite anode material according to claim 1, characterized in that: The ultrasonic power is 300~500 W, and the duration is 1~2 h.

8. The iron oxide / carbon-based composite anode material prepared by the preparation method of the iron oxide / carbon-based composite anode material according to any one of claims 1 to 7.

9. The application of the iron oxide / carbon-based composite anode material according to claim 8 in lithium battery anode sheets.

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