Charge-discharge efficiency improving technology of high-capacity natural graphite-based negative electrode material

Abstract

The invention discloses a charge-discharge efficiency improving technology of a high-capacity natural graphite-based negative electrode material, which comprises the preparation of the high-capacity natural graphite-based negative electrode material, and the preparation method of the high-capacity natural graphite-based negative electrode material comprises the following steps: A, mixing raw materials, and adding into a ball mill for ball milling to obtain a mixture A; b, adding the mixture A into a preheating furnace for heating and preheating; c, transferring the preheated mixture into a high-temperature furnace for high-temperature carbonization, and introducing inert gas in the carbonization process; and D, transferring into a high-temperature graphite furnace, carrying out graphitization reaction, and carrying out ball milling on the material subjected to high-temperature graphitization to prepare the required high-capacity natural graphite-based negative electrode material. The negative electrode material prepared by the preparation method of the high-capacity natural graphite-based negative electrode material has high conductivity, and the internal resistance of a negative electrode can be effectively reduced, so that relatively high capacitance, charge-discharge speed and large-current charge-discharge performance are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of natural graphite-based negative electrode material preparation, in particular to a technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials. Background Art

[0002] Lithium-ion batteries have successfully replaced other secondary batteries with their advantages of high specific energy, high operating voltage, fast charge and discharge speed, long cycle life, safety and pollution-free, and have become the main energy source for small electronic products such as mobile phones, laptops and camcorders. They have also greatly promoted the industrialization of electric vehicles. Many countries have also fully launched the development of lithium-ion batteries in the military and aerospace fields, which has put forward higher requirements for lithium-ion batteries. Electrode materials are the key to improving the performance of lithium-ion batteries and directly affect the charge and discharge performance of batteries. Since the birth and successful commercialization of lithium-ion batteries in the early 1990s, negative electrode materials have always been a research focus. So far, the main negative electrode materials studied include graphite, amorphous carbon, alloys and metal oxides, among which graphite occupies a dominant position in the lithium-ion battery negative electrode material market, with a market share of up to 90%. The research is also the most mature and has been successfully applied to small and medium-sized electronic products.

[0003] Natural graphite has high crystallinity, good conductivity, and a good layered structure, making it more suitable for the embedding and extraction of lithium ions during the charging and discharging process. In addition, natural graphite resources are abundant and inexpensive. Therefore, graphite negative electrode materials have always been the research and development focus of the world's six major battery companies, including Shanshan and BYD.

[0004] Currently, the main purpose of providing charge and discharge stability and charge and discharge capacity for lithium-ion negative electrode materials is to passivate the graphitization of the surface through surface modification, thereby improving stability. However, the currently produced graphite negative electrode materials have unstable structures and low single-charge capacity. Therefore, it is necessary to make improvements. Summary of the invention

[0005] The purpose of the present invention is to provide a technology for improving the charge and discharge efficiency of a high-capacity natural graphite-based negative electrode material to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a technology for improving the charge and discharge efficiency of a high-capacity natural graphite-based negative electrode material, including preparing a high-capacity natural graphite-based negative electrode material, and a method for preparing a high-capacity natural graphite-based negative electrode material is as follows:

[0007] A. First, the raw materials are mixed and added into a ball mill for ball milling to obtain a mixture A;

[0008] B. Add mixture A into a preheating furnace for preheating;

[0009] C. Transferring the preheated mixture to a high temperature furnace for high temperature carbonization, and introducing inert gas during the carbonization process;

[0010] D. Then transfer it to a high-temperature graphite furnace for graphitization reaction, and then ball mill the high-temperature graphitized material to prepare the required high-capacity natural graphite-based negative electrode material.

[0011] Preferably, the raw material components in step A include 50-80 parts by weight of natural graphite, 40-60 parts of single-walled carbon nanotubes, 20-30 parts of nanoporous silicon, and 20-40 parts of modified asphalt particles.

[0012] Preferably, the preferred composition ratio of the raw material components in step A includes 65 parts of natural graphite, 50 parts of single-walled carbon nanotubes, 25 parts of nanoporous silicon, and 30 parts of modified asphalt particles.

[0013] Preferably, in the ball milling process in step A, the ball milling speed is 2000-3000 r / min, and the time is 20 min-30 min.

[0014] Preferably, in step B, the preheating temperature is 300° C.-400° C., and the preheating time is 50 min-60 min.

[0015] Preferably, in step C, carbonization is carried out under the protection of a nitrogen atmosphere, and the carbonization process is firstly increased to 500°C-540°C at a rate of 2°C-3°C / min, and maintained at this temperature for 2h-3h; then increased to 580°C-650°C at a rate of 1°C-2°C / min and maintained for 2h-3h; finally increased to 760-960°C at a rate of 2-6°C / min, and maintained at this temperature for 2h-3h to obtain a carbonized material.

[0016] Preferably, in step D, the graphitization reaction temperature in the high-temperature graphite furnace is 2000-2400° C., and the graphitization reaction time is 2-3 hours.

[0017] Preferably, in the ball milling process in step D, the ball milling speed is 4000-5000 r / min, and the time is 20 min-30 min.

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

[0019] (1) The negative electrode material prepared by the high-capacity natural graphite-based negative electrode material preparation method adopted in the present invention has high conductivity and can effectively reduce the internal resistance of the negative electrode, thereby achieving higher capacitance, charge and discharge speed and high current charge and discharge performance.

[0020] (2) The present invention has low requirements on atmosphere, temperature and raw materials, and has the advantages of simple operation, short process and low cost. The obtained high-capacity natural graphite-based negative electrode material has high conductive efficiency.

[0021] (3) The high-temperature carbonization step of the present invention can improve the reaction efficiency, reduce the reaction interface of the high-temperature graphitization process, and can increase the charge and discharge efficiency to more than 97.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a flow chart of the preparation method. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them. They are not used to limit the conditions under which this application can be implemented, so they have no substantive technical significance. Any structural modification, change in proportion or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0025] Embodiment 1:

[0026] See also Figure 1 The present invention provides a technical solution: a technology for improving the charge and discharge efficiency of a high-capacity natural graphite-based negative electrode material, including preparing a high-capacity natural graphite-based negative electrode material. The preparation method of the high-capacity natural graphite-based negative electrode material is as follows:

[0027] A. First, the raw materials are mixed and added into a ball mill for ball milling to obtain a mixture A;

[0028] B. Add mixture A into a preheating furnace for preheating;

[0029] C. Transferring the preheated mixture to a high temperature furnace for high temperature carbonization, and introducing inert gas during the carbonization process;

[0030] D. Then transfer it to a high-temperature graphite furnace for graphitization reaction, and then ball mill the high-temperature graphitized material to prepare the required high-capacity natural graphite-based negative electrode material.

[0031] In this embodiment, the raw material components in step A include 50 parts of natural graphite, 40 parts of single-walled carbon nanotubes, 20 parts of nanoporous silicon, and 20 parts of modified asphalt particles by weight.

[0032] In this embodiment, the ball milling speed during the ball milling process in step A is 2000 r / min and the time is 20 min.

[0033] In this embodiment, the preheating temperature in step B is 300° C. and the preheating time is 50 min.

[0034] In this embodiment, carbonization is carried out under the protection of a nitrogen atmosphere in step C, and the carbonization process is firstly increased to 500°C at a rate of 2°C / min and maintained at this temperature for 2 hours; then increased to 580°C at a rate of 1°C / min and maintained for 2 hours; finally increased to 760°C at a rate of 2°C / min, and maintained at this temperature for 2 hours to obtain a carbonized material.

[0035] In this embodiment, the graphitization reaction temperature in the high-temperature graphite furnace in step D is 2000° C., and the graphitization reaction time is 2 hours.

[0036] In this embodiment, the ball milling speed during the ball milling process in step D is 4000 r / min and the time is 20 min.

[0037] Embodiment 2:

[0038] A technology for improving the charge and discharge efficiency of a high-capacity natural graphite-based negative electrode material includes preparing a high-capacity natural graphite-based negative electrode material. The preparation method of the high-capacity natural graphite-based negative electrode material is as follows:

[0039] A. First, the raw materials are mixed and added into a ball mill for ball milling to obtain a mixture A;

[0040] B. Add mixture A into a preheating furnace for preheating;

[0041] C. Transferring the preheated mixture to a high temperature furnace for high temperature carbonization, and introducing inert gas during the carbonization process;

[0042] D. Then transfer it to a high-temperature graphite furnace for graphitization reaction, and then ball mill the high-temperature graphitized material to prepare the required high-capacity natural graphite-based negative electrode material.

[0043] In this embodiment, the raw material components in step A include 80 parts of natural graphite, 60 parts of single-walled carbon nanotubes, 30 parts of nanoporous silicon, and 40 parts of modified asphalt particles by weight.

[0044] In this embodiment, the ball milling speed during the ball milling process in step A is 3000 r / min and the time is 30 min.

[0045] In this embodiment, the preheating temperature in step B is 400° C. and the preheating time is 60 minutes.

[0046] In this embodiment, in step C, carbonization is carried out under the protection of a nitrogen atmosphere, and the carbonization process is firstly increased to 540°C at a rate of 3°C / min and maintained at this temperature for 3 hours; then increased to 650°C at a rate of 2°C / min and maintained for 3 hours; finally increased to 960°C at a rate of 6°C / min, and maintained at this temperature for 3 hours to obtain a carbonized material.

[0047] In this embodiment, the graphitization reaction temperature in the high-temperature graphite furnace in step D is 2400° C., and the graphitization reaction time is 3 hours.

[0048] In this embodiment, the ball milling speed during the ball milling process in step D is 5000 r / min and the time is 30 min.

[0049] Embodiment three:

[0050] A technology for improving the charge and discharge efficiency of a high-capacity natural graphite-based negative electrode material includes preparing a high-capacity natural graphite-based negative electrode material. The preparation method of the high-capacity natural graphite-based negative electrode material is as follows:

[0051] A. First, the raw materials are mixed and added into a ball mill for ball milling to obtain a mixture A;

[0052] B. Add mixture A into a preheating furnace for preheating;

[0053] C. Transferring the preheated mixture to a high temperature furnace for high temperature carbonization, and introducing inert gas during the carbonization process;

[0054] D. Then transfer it to a high-temperature graphite furnace for graphitization reaction, and then ball mill the high-temperature graphitized material to prepare the required high-capacity natural graphite-based negative electrode material.

[0055] In this embodiment, the raw material components in step A include 55 parts of natural graphite, 45 parts of single-walled carbon nanotubes, 22 parts of nanoporous silicon, and 24 parts of modified asphalt particles by weight.

[0056] In this embodiment, the ball milling speed during the ball milling process in step A is 2200 r / min and the time is 22 min.

[0057] In this embodiment, the preheating temperature in step B is 320° C. and the preheating time is 52 minutes.

[0058] In this embodiment, in step C, carbonization is carried out under the protection of a nitrogen atmosphere, and the carbonization process is firstly increased to 510°C at a rate of 2°C / min and maintained at this temperature for 2 hours; then increased to 590°C at a rate of 1°C / min and maintained for 2 hours; finally increased to 790°C at a rate of 3°C / min, and maintained at this temperature for 2 hours to obtain a carbonized material.

[0059] In this embodiment, the graphitization reaction temperature in the high-temperature graphite furnace in step D is 2100° C., and the graphitization reaction time is 2 hours.

[0060] In this embodiment, the ball milling speed during the ball milling process in step D is 4200 r / min and the time is 23 min.

[0061] Embodiment 4:

[0062] A technology for improving the charge and discharge efficiency of a high-capacity natural graphite-based negative electrode material includes preparing a high-capacity natural graphite-based negative electrode material. The preparation method of the high-capacity natural graphite-based negative electrode material is as follows:

[0063] A. First, the raw materials are mixed and added into a ball mill for ball milling to obtain a mixture A;

[0064] B. Add mixture A into a preheating furnace for preheating;

[0065] C. Transferring the preheated mixture to a high temperature furnace for high temperature carbonization, and introducing inert gas during the carbonization process;

[0066] D. Then transfer it to a high-temperature graphite furnace for graphitization reaction, and then ball mill the high-temperature graphitized material to prepare the required high-capacity natural graphite-based negative electrode material.

[0067] In this embodiment, the raw material components in step A include 75 parts of natural graphite, 55 parts of single-walled carbon nanotubes, 28 parts of nanoporous silicon, and 35 parts of modified asphalt particles by weight.

[0068] In this embodiment, the ball milling speed during the ball milling process in step A is 2800 r / min and the time is 28 min.

[0069] In this embodiment, the preheating temperature in step B is 380° C. and the preheating time is 58 minutes.

[0070] In this embodiment, in step C, carbonization is carried out under the protection of a nitrogen atmosphere, and the carbonization process is firstly increased to 530°C at a rate of 3°C / min and maintained at this temperature for 3 hours; then increased to 620°C at a rate of 2°C / min and maintained for 3 hours; finally increased to 880°C at a rate of 5°C / min, and maintained at this temperature for 3 hours to obtain a carbonized material.

[0071] In this embodiment, the graphitization reaction temperature in the high-temperature graphite furnace in step D is 2300° C., and the graphitization reaction time is 3 hours.

[0072] In this embodiment, the ball milling speed during the ball milling process in step D is 4800 r / min and the time is 28 min.

[0073] Embodiment five:

[0074] A technology for improving the charge and discharge efficiency of a high-capacity natural graphite-based negative electrode material includes preparing a high-capacity natural graphite-based negative electrode material. The preparation method of the high-capacity natural graphite-based negative electrode material is as follows:

[0075] A. First, the raw materials are mixed and added into a ball mill for ball milling to obtain a mixture A;

[0076] B. Add mixture A into a preheating furnace for preheating;

[0077] C. Transferring the preheated mixture to a high temperature furnace for high temperature carbonization, and introducing inert gas during the carbonization process;

[0078] D. Then transfer it to a high-temperature graphite furnace for graphitization reaction, and then ball mill the high-temperature graphitized material to prepare the required high-capacity natural graphite-based negative electrode material.

[0079] In this embodiment, the raw material components in step A include 65 parts of natural graphite, 50 parts of single-walled carbon nanotubes, 25 parts of nanoporous silicon, and 30 parts of modified asphalt particles by weight.

[0080] In this embodiment, the ball milling speed during the ball milling process in step A is 2500 r / min and the time is 25 min.

[0081] In this embodiment, the preheating temperature in step B is 350° C. and the preheating time is 55 minutes.

[0082] In this embodiment, in step C, carbonization is carried out under the protection of a nitrogen atmosphere, and the carbonization process is firstly increased to 520°C at a rate of 2.5°C / min and maintained at this temperature for 2.5 hours; then increased to 600°C at a rate of 1.5°C / min and maintained for 2.5 hours; finally increased to 830°C at a rate of 4°C / min, and maintained at this temperature for 2.5 hours to obtain a carbonized material.

[0083] In this embodiment, the graphitization reaction temperature in the high-temperature graphite furnace in step D is 2200° C., and the graphitization reaction time is 2.5 h.

[0084] In this embodiment, the ball milling speed during the ball milling process in step D is 4500 r / min and the time is 25 min.

[0085] Experimental example:

[0086] The positive charge and discharge performance test of the negative electrode materials prepared by various embodiments of the present invention obtained the following data:

[0087]

[0088] The present invention has low requirements on atmosphere, temperature and raw materials, and has the advantages of simple operation, short process and low cost. The obtained high-capacity natural graphite-based negative electrode material has high conductivity efficiency. The high-temperature carbonization step of the present invention can improve the reaction efficiency, reduce the reaction interface of the high-temperature graphitization process, and can increase the charge and discharge efficiency to more than 97.5%.

[0089] In summary, the negative electrode material prepared by the high-capacity natural graphite-based negative electrode material preparation method adopted in the present invention has high conductivity and can effectively reduce the internal resistance of the negative electrode, thereby achieving higher capacity, charge and discharge speed and high current charge and discharge performance.

[0090] It should also be noted that, in this specification, 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 "comprise", "include" 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. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. Technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials, characterized by: The invention comprises preparing a high-capacity natural graphite-based negative electrode material, and the preparation method of the high-capacity natural graphite-based negative electrode material is as follows: A. First, the raw materials are mixed and added into a ball mill for ball milling to obtain a mixture A; B. Add mixture A into a preheating furnace for preheating; C. Transferring the preheated mixture to a high temperature furnace for high temperature carbonization, and introducing inert gas during the carbonization process; D. Then transfer it to a high-temperature graphite furnace for graphitization reaction, and then ball mill the high-temperature graphitized material to prepare the required high-capacity natural graphite-based negative electrode material.

2. The technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials according to claim 1, characterized in that: The raw material components in step A include 50-80 parts by weight of natural graphite, 40-60 parts of single-walled carbon nanotubes, 20-30 parts of nanoporous silicon, and 20-40 parts of modified asphalt particles.

3. The technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials according to claim 2, characterized in that: The preferred composition ratio of the raw material components in step A includes 65 parts of natural graphite, 50 parts of single-walled carbon nanotubes, 25 parts of nanoporous silicon, and 30 parts of modified asphalt particles.

4. The technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials according to claim 1, characterized in that: In the ball milling process in step A, the ball milling speed is 2000-3000 r / min, and the time is 20 min-30 min.

5. The technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials according to claim 1, characterized in that: In step B, the preheating temperature is 300° C.-400° C., and the preheating time is 50 min-60 min.

6. The technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials according to claim 1, characterized in that: In the step C, carbonization is carried out under the protection of a nitrogen atmosphere. The carbonization process is firstly to increase the temperature to 500-540°C at a rate of 2°C-3°C / min, and to maintain the temperature for 2h-3h; then to increase the temperature to 580-650°C at a rate of 1°C-2°C / min and to maintain the temperature for 2h-3h; finally, to increase the temperature to 760-960°C at a rate of 2-6°C / min, and to maintain the temperature for 2h-3h to obtain a carbonized material.

7. The technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials according to claim 1, characterized in that: In the step D, the graphitization reaction temperature in the high-temperature graphite furnace is 2000-2400° C., and the graphitization reaction time is 2-3 hours.

8. The technology for improving the charge and discharge efficiency of high-capacity natural graphite-based negative electrode materials according to claim 1, characterized in that: In the ball milling process in step D, the ball milling speed is 4000-5000 r / min, and the time is 20 min-30 min.

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