Preparation method of novel rate type interlayer compound

Abstract

The invention discloses a preparation method of a novel rate type interlayer compound. The preparation method specifically comprises the following steps: step 1, pretreating powder; step 2, carbonization treatment; step 3, spheroidizing strengthening treatment; step 4, carrying out graphitization treatment; step 5, screening a finished product; the invention relates to the technical field of lithium ion battery negative electrode materials. According to the preparation method of the novel multiplying power type interlayer compound, the energy density of a battery and the specific capacity of a finished product are improved through cooperation of the composite easily-graphitized coke, the nano Fe / Ni catalyst and the lignin, a gradient core-shell structure of an inner core soft carbon layer and an outer shell hard carbon layer is obtained through periodic pressure adjustment, the cycling stability is improved, and meanwhile the specific capacity of the battery is improved. Under cooperation of a carbon dioxide atmosphere, densification of a carbon layer is guaranteed, spheroidizing is carried out in a segmented temperature control and variable-speed stirring mode, the particle morphology is optimized, the conductivity and mechanical strength of particles are further enhanced in cooperation with graphene, and the comprehensive performance of the novel rate type interlayer compound is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of negative electrode materials for lithium ion batteries, and in particular to a method for preparing a novel rate-type intercalation compound. Background Art

[0002] Lithium-ion batteries have been increasingly used in electronic products, electric vehicles, solar and wind power generation and energy storage, etc. With the adjustment of the national policy on the development of new energy vehicle industry and the higher requirements of new energy vehicle companies on the service life of lithium batteries, the research on lithium battery negative electrode materials is currently shifting towards high capacity, high rate, long cycle and low price.

[0003] In order to improve the cycle performance of lithium battery negative electrode materials and at the same time improve the specific capacity and charge and discharge rate of negative electrode materials, a common modification method is to coat the particle surface, that is, to evenly mix asphalt and graphite, and then carbonize or graphitize, so as to form a carbonized protective layer on the surface of graphite particles. However, this method still has the following problems:

[0004] 1. Limited performance improvement: The uniformity and density of the carbonized protective layer are difficult to accurately control, resulting in limited performance improvement.

[0005] 2. Material loss: During multiple processing processes, the material loss rate is high, affecting economic benefits.

[0006] To this end, a method for preparing a new type of rate-type interlayer compound is proposed to effectively improve the uniformity and density of the carbonized protective layer, reduce material loss, and effectively improve the comprehensive performance of the new type of rate-type interlayer compound. Summary of the invention

[0007] In view of the deficiencies of the prior art, the present invention provides a method for preparing a novel rate-type intercalation compound, which solves the problems raised in the above-mentioned background technology.

[0008] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for preparing a novel intercalation compound of a multiplier type, specifically comprising the following steps:

[0009] Step 1: Pretreatment of powder: After pretreatment of the composite graphitizable coke, 0.5-1.5wt% of nano Fe / Ni catalyst and 1.0wt% of lignin are added, and graded and crushed to obtain powder;

[0010] Step 2, carbonization treatment: After the powder is compacted, it is loaded into a pit carbonization furnace, a carbon dioxide atmosphere is introduced, and it is electrically heated to 1200°C-1350°C at a frequency of 50Hz. The carbonization treatment is performed for 1-5 hours, and the pressure is adjusted periodically during the process to obtain a precursor;

[0011] Step 3: Spheroidization enhancement treatment: Put the precursor into the spheroidization equipment, add graphene, and perform spheroidization treatment in a way of segmented temperature control and variable-speed stirring to obtain spheroidized powder;

[0012] Step 4: Graphitization treatment: Put the spheroidized powder into a graphitization furnace and perform segmented heat preservation to obtain graphitized powder;

[0013] Step 5: Finished product screening: Use the combined technology of air classification and electrostatic adsorption to classify and homogenize the graphitized powder to obtain the finished product.

[0014] The present invention is further configured as: The composite easily graphitizable coke includes petroleum coke and needle coke, and the petroleum coke and needle coke include 3:2 by weight ratio.

[0015] The present invention is further configured as: The method for pretreating the composite easily graphitizable coke in Step 1 includes: Pickling and impurity removal of the composite easily graphitizable coke.

[0016] The present invention is further configured as: When performing graded crushing in Step 1, the powder particle size D50 is controlled within 5 - 8 μm, and the powder particle size D90 is controlled within 15 μm.

[0017] The present invention is further configured as: The method for performing periodic pressure regulation in Step 2 includes:

[0018] Set a pressure pulsation device in the pit-type carbonization furnace to perform periodic pressure regulation at 0.1 - 0.5 MPa / 5 min.

[0019] The present invention is further configured as: The method for performing spheroidization treatment in a way of segmented temperature control and variable-speed stirring in Step 3 includes:

[0020] Preheating stage: Heat up to 400 °C, and stir at a speed of 15 r / min for 2 h simultaneously;

[0021] Main treatment stage: Heat up to 600 °C, increase the speed to 25 r / min, and continuously stir for 16 h;

[0022] Final treatment stage: Heat up to 800 °C, increase the speed to 30 r / min, and continuously stir for 6 h.

[0023] The present invention is further configured as: The method for obtaining graphitized powder by segmented heat preservation in Step 4 includes:

[0024] Heat up to 2600 °C and keep warm for 2 h to preliminarily graphitize the material;

[0025] Heat up to 2800 °C and keep warm for 3 h to promote the improvement of the graphitization degree;

[0026] Heat up to 3000 °C and hold for 1 h to complete the final graphitization.

[0027] The present invention is further configured such that when the airflow classification and electrostatic adsorption combination technology is used to classify and homogenize the graphitized powder in the fifth step, the particle size D50 of the powder is controlled to be 5-8 μm.

[0028] The present invention provides a preparation method of a novel intercalation compound of the rate type. It has the following beneficial effects:

[0029] By the cooperation of the composite graphitizable coke, the nano Fe / Ni catalyst and lignin, while increasing the compaction density, the energy density of the battery is increased, and the specific capacity of the finished product is increased. During the carbonization treatment, periodic pressure regulation is used to obtain a gradient core-shell structure of a soft carbon layer in the core and a hard carbon layer in the shell. While improving the cycle stability, with the cooperation of a carbon dioxide atmosphere, the densification of the carbon layer is ensured, and the spheroidization treatment is carried out by combining segmented temperature control and variable-speed stirring to optimize the particle morphology. With the cooperation of graphene, the conductivity and mechanical strength of the particles are further enhanced. By reducing the graphitization treatment duration, the energy consumption is reduced, and the comprehensive performance of the novel intercalation compound of the rate type can be effectively improved. Description of the Drawings

[0030] Figure 1 It is a process schematic diagram of the present invention. Specific Embodiments

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention.

[0032] Please refer to Figure 1 , the embodiments of the present invention provide the following technical solutions:

[0033] Example 1

[0034] A preparation method of a novel intercalation compound of the rate type specifically includes the following steps:

[0035] Step 1. Powder pretreatment: Pickling and impurity removal are carried out on the composite graphitizable coke. Among them, the composite graphitizable coke includes petroleum coke and needle coke, and the petroleum coke and needle coke include 3:2 by weight. Add 0.5 wt% of the nano Fe / Ni catalyst and 1.0 wt% of lignin, and perform classification and crushing. When performing classification and crushing, the particle size D50 of the powder is controlled to be 5-8 μm, and the particle size D90 of the powder is controlled within 15 μm to obtain the powder.

[0036] Step 2. Carbonization treatment: After tamping the powder materials, load them into a pit-type carbonization furnace, introduce a carbon dioxide atmosphere, heat them to 1200°C - 1350°C with 50Hz power frequency electricity, and carry out carbonization treatment for 1 - 5h. During the process, perform periodic pressure regulation to obtain a precursor. The methods for periodic pressure regulation include:

[0037] Install a pressure pulsation device in the pit-type carbonization furnace, and perform periodic pressure regulation at 0.1 - 0.5MPa / 5min to promote the directional migration of volatile components, form a gradient core-shell structure with a soft carbon layer in the core and a hard carbon layer in the shell, and improve the cycle stability.

[0038] Step 3. Spheroidization and strengthening treatment: Put the precursor into a spheroidization device, add graphene. The spheroidization device is a kettle-type coating device, and adopt a stirring method with the main shaft rotating together with the helical ribbon. At the same time, perform heat treatment and carry out spheroidization treatment in the way of segmented temperature control and variable-speed stirring to obtain spheroidized powder. The ways of carrying out spheroidization treatment in the way of segmented temperature control and variable-speed stirring include:

[0039] Preheating stage: Heat up to 400°C, and stir at a speed of 15r / min for 2h at the same time to make the particles preliminarily uniform;

[0040] Main treatment stage: Heat up to 600°C, increase the speed to 25r / min, and continuously stir for 16h to make the particles gradually spheroidize and form an isotropic structure.

[0041] Final treatment stage: Heat up to 800°C, increase the speed to 30r / min, and continuously stir for 6h to further optimize the surface smoothness and compactness of the particles.

[0042] Step 4. Graphitization treatment: Put the spheroidized powder into a graphitization furnace, and obtain graphitized powder through segmented heat preservation. The ways of obtaining graphitized powder through segmented heat preservation include:

[0043] Heat up to 2600°C and keep it warm for 2h to make the material preliminarily graphitized;

[0044] Heat up to 2800°C and keep it warm for 3h to promote the improvement of the graphitization degree;

[0045] Heat up to 3000°C and keep it warm for 1h to complete the final graphitization.

[0046] It can be seen that the total duration of the graphitization treatment is 6h. Compared with the conventional 8h treatment, it has an obvious advantage of energy consumption reduction, and the compaction density of the graphitized powder is increased to ≥0.60g / cm 3 , and the specific capacity is increased by 15% - 20%.

[0047] Step 5. Finished product screening: Use the technology combining air classification and electrostatic adsorption to carry out classification treatment and homogenization treatment on the graphitized powder, control the particle size D50 of the powder within 5 - 8μm, and obtain the finished product.

[0048] Embodiment 2

[0049] The difference between this embodiment and the first embodiment is that 1.0 wt% of nano Fe / Ni catalyst is added.

[0050] Embodiment 3

[0051] The present embodiment is different from the first embodiment in that 1.5 wt % of nano Fe / Ni catalyst is added.

[0052] Simulation experiment

[0053] After obtaining the finished product according to the preparation method provided in the above-mentioned embodiment 1, embodiment 2 and embodiment 3, samples 1, sample 2 and sample 3 were taken in sequence for performance testing. The test results are shown in Table 1:

[0054] Energy density (Wh / kg) Specific capacity (mAh / g) Cycle life / times Capacity retention rate / % Sample 1 340 350 1800 90 Sample 2 350 360 2000 92 Sample 3 360 380 2200 94

[0055] Table 1

[0056] As can be seen from Table 1, the preparation method of the novel rate-type intercalation compound provided by the present invention has good advantages in energy density, specific capacity, cycle life and capacity retention, and can provide strong technical support for the development of high-performance energy storage materials.

[0057] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a novel intercalation compound of the magnification type, characterized in that: Specifically, it includes the following steps: Step 1, powder pretreatment: After pretreating the composite easily graphitizable coke, add 0.5 - 1.5 wt% of nano Fe / Ni catalyst and 1.0 wt% of lignin, and perform fractional crushing to obtain powders; Step 2, carbonization treatment: After tamping the powders, load them into a pit-type carbonization furnace, introduce a carbon dioxide atmosphere, heat them to 1200℃ - 1350℃ with 50Hz power frequency electric heating, and perform carbonization treatment for 1 - 5h. During the process, perform periodic pressure regulation to obtain a precursor; Step 3, spheroidization strengthening treatment: Put the precursor into a spheroidization device, add graphene, and perform spheroidization treatment in a way of segmented temperature control and variable-speed stirring to obtain spheroidized powder; Step 4, graphitization treatment: Place the spheroidized powder into a graphitization furnace, and perform segmented heat preservation to obtain graphitized powder; Step 5, finished product screening: Use the technology combining air classification and electrostatic adsorption to perform classification treatment and homogenization treatment on the graphitized powder to obtain the finished product.

2. The preparation method of a novel intercalation compound of magnification type according to claim 1, characterized in that: The composite easily graphitizable coke includes petroleum coke and needle coke, and the petroleum coke and needle coke are in a weight ratio of 3:

2.

3. The preparation method of a novel intercalation compound of magnification type according to claim 1, characterized in that: The method for pretreating the composite easily graphitizable coke in Step 1 includes: performing acid washing to remove impurities on the composite easily graphitizable coke.

4. The preparation method of a novel intercalation compound of magnification type according to claim 1, wherein: When performing fractional crushing in Step 1, the powder particle size D50 is controlled within 5 - 8μm, and the powder particle size D90 is controlled within 15μm.

5. The preparation method of a novel intercalation compound of magnification type according to claim 1, characterized in that: The method for performing periodic pressure regulation in Step 2 includes: Set a pressure pulsation device in the pit-type carbonization furnace, and perform periodic pressure regulation at 0.1 - 0.5MPa / 5min.

6. The preparation method of a novel intercalation compound of magnification type according to claim 1, characterized in that: The method for performing spheroidization treatment in a way of segmented temperature control and variable-speed stirring in Step 3 includes: Preheating stage: Heat up to 400℃, and stir at a speed of 15r / min for 2h; Main treatment stage: Heat up to 600℃, increase the speed to 25r / min, and continuously stir for 16h; Final treatment stage: Heat up to 800℃, increase the speed to 30r / min, and continuously stir for 6h.

7. The preparation method of a novel intercalation compound of magnification type according to claim 1, characterized in that: The method for obtaining graphitized powder by segmented heat preservation in Step 4 includes: Heat up to 2600℃ and keep warm for 2h; Heat up to 2800℃ and keep warm for 3h; Heat up to 3000℃ and keep warm for 1h.

8. The preparation method of a novel intercalation compound of the magnification type according to claim 1, wherein: When using the technology combining air classification and electrostatic adsorption to perform classification treatment and homogenization treatment on the graphitized powder in Step 5, the powder particle size D50 is controlled within 5 - 8μm.

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