Porous three-dimensional battery negative electrode material prepared by using palm empty fruit bunches, and preparation method therefor

Abstract

A porous three-dimensional battery negative electrode material prepared by using palm empty fruit bunches, which has a relatively large porosity, facilitating entering of relatively large ions such as sodium ions. A preparation method for the porous three-dimensional battery negative electrode material comprises the following steps: a, collecting palm empty fruit bunches as a raw material, and crushing the raw material; b, carrying out incipient carbonization on the crushed material; c, carrying out graphitization in an inert gas atmosphere; d, crushing the obtained material again; and e, carrying out pre-lithiation or pre-sodium treatment to obtain a porous three-dimensional battery negative electrode material. The method involves simple steps and is easy to operate.

Description

Porous three-dimensional battery negative electrode material made from empty palm fruit bunches and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a porous three-dimensional battery negative electrode material made from empty palm fruit bunches and a preparation method thereof. Background Art

[0002] Currently, lithium-ion batteries account for the vast majority of new battery types. With technological advancements, lithium-ion battery technology has become increasingly mature, and manufacturing costs have also decreased. However, lithium metal is obtained through mining. Over time, mineral reserves will eventually be depleted due to continuous mining. Sodium salts, on the other hand, are abundant in nature. In fact, sodium-ion batteries were invented in the 1970s. However, during the subsequent industrialization process, the lack of suitable anode materials and the rapid development of lithium-ion battery technology meant that sodium-ion battery technology fell behind.

[0003] After comparison, it is found that sodium ion batteries have the following advantages over lithium ion batteries: (1) From the perspective of raw materials for the positive electrode, the recent price of lithium carbonate is 570,000 yuan per ton, while the price of sodium carbonate is less than 3,000 yuan per ton. It can be seen that the raw material cost of sodium ion batteries is much lower than that of lithium ion batteries; (2) Sodium ion batteries do not have over-discharge characteristics, so theoretically sodium ion batteries can be discharged to 0 volts, while lithium ion batteries cannot be completely discharged, otherwise the graphite interlayer structure of the negative electrode of the lithium ion battery may collapse, thereby affecting the secondary entrapment of lithium ions. Secondly, sodium ion batteries still maintain a retention rate of more than 90% at minus 20 degrees Celsius and a retention rate of more than 70% at minus 40 degrees Celsius; (3) Sodium ion batteries have higher electrical conductivity and weaker ion diffusion capacity, which means that their backup performance is better. They have a charge and discharge rate of at least 3C. Therefore, the power output of sodium ion batteries will be stronger and the high-power fast charging speed will be faster. Therefore, sodium ion batteries also have great application prospects.

[0004] After research, it was found that the structures of sodium-ion batteries and lithium-ion batteries are very similar. Both are rocking-chair batteries, and both rely on a metal ion to shuttle back and forth between the positive and negative electrodes. However, the negative electrode of a lithium-ion battery is made of graphite. The relative atomic mass of lithium is 7, but the relative atomic mass of sodium is 23. The size of sodium ions is larger than that of lithium ions and cannot be embedded in the graphite layer. If graphite is continued to be used as the negative electrode material of sodium-ion batteries, the interlayer distance of graphite must be increased, which will obviously increase the manufacturing cost and reduce the structural stability of the negative electrode. For this reason, it is necessary to design a new type of negative electrode material to meet the application of negative electrode materials for sodium-ion batteries, and it can also be applied to batteries with other positive electrode materials such as lithium-ion batteries.

[0005] Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a porous three-dimensional battery negative electrode material made from palm fruit bunches. The battery negative electrode material has large pores and is naturally porous, which can meet the entry of ions with a large volume.

[0007] The present invention also provides a method for preparing the above-mentioned porous three-dimensional battery negative electrode material. The method has simple steps and is easy to operate. The battery negative electrode material prepared by this method has larger pores, which facilitates the entry of ions with larger volume such as sodium ions.

[0008] The technical solution adopted by the porous three-dimensional battery negative electrode material made from empty palm fruit bunches of the present invention is that the porous three-dimensional battery negative electrode material is prepared from empty palm fruit bunches, and the porous three-dimensional battery negative electrode material has natural porosity.

[0009] As can be seen from the above scheme, the natural porous structure characteristics of palm fruit bunches with large pores are utilized to make the prepared battery negative electrode material have natural porosity, which satisfies the passage of large-volume ions and makes the battery negative electrode material more widely applicable.

[0010] Furthermore, the porous three-dimensional battery negative electrode material is prepared from empty palm fruit bunches after oil extrusion. Thus, using empty palm fruit bunches after oil extrusion to prepare the porous three-dimensional battery negative electrode material not only achieves waste utilization and environmental protection, but also allows the empty palm fruit bunches to be pre-processed during the oil extrusion process, facilitating further processing in subsequent steps.

[0011] The technical solution adopted by the method of the present invention for preparing the above-mentioned porous three-dimensional battery negative electrode material is that the method of the present invention comprises the following steps:

[0012] a. Collect empty palm fruit bunches as raw materials and crush the raw materials;

[0013] b. The crushed material is heated and smoldered to perform initial carbonization, wherein the heating temperature is 380℃~700℃;

[0014] c. After the initial carbonization, the material is heated to 1800℃~3000℃ and graphitized under an inert gas atmosphere;

[0015] d. After the material is graphitized, it is crushed to obtain a powder material with a particle size range of 200nm to 50μm;

[0016] e. Pre-lithiation or pre-sodiumization is performed by chemical vapor deposition to obtain the final porous three-dimensional battery negative electrode material.

[0017] It can be seen from the above scheme that the method of the present invention has simple steps and is easy to operate. In this method, empty palm fruit bunches are selected as raw materials, which are crushed and then heated and smoldered to obtain a preliminary carbonized material. The material is then graphitized in an inert gas atmosphere within a temperature range of 1800°C to 3000°C, and then crushed to form natural porous materials with large pores between the graphite layers. These natural porous pores are large enough to allow larger ions to pass through, and finally pre-lithiation or pre-sodiumization is performed to form a lithium film or sodium film on the surface of the material particles, thereby avoiding damage to the battery diaphragm caused by the protrusions on the surface of the material particles, thereby ensuring the safety of the battery. In addition, the battery negative electrode material prepared by this method has larger pores, which facilitates the entry of larger ions such as sodium ions.

[0018] Furthermore, in step e, after pre-lithiation by chemical vapor deposition, a further step of pre-siliconization by chemical vapor deposition is also included to obtain the final porous three-dimensional battery negative electrode material. Thus, for lithium positive electrode materials, siliconization treatment is performed to form a further silicon film on the surface of the material particles, thereby forming further protection for the separator in the lithium-ion battery, making the lithium-ion battery structure safer and more stable.

[0019] Furthermore, in step a, the raw material is crushed to a particle size of 1 mm to 200 mm. Thus, crushing the raw material to a particle size of 1 mm to 200 mm makes the raw material more fully processed in the subsequent carbonization process, which can effectively improve the carbonization efficiency.

[0020] Furthermore, in step d, the particle size of the powdered material obtained after pulverization is in the range of 500 nm to 50 μm. Therefore, the particle size of the pulverized material is in the range of 500 nm to 50 μm, which provides a guarantee for the subsequent preparation of a porous three-dimensional battery negative electrode material with better quality.

[0021] Furthermore, in step c, when the temperature is below 2000°C, graphitization is performed under a nitrogen atmosphere; when the temperature is above 2000°C, graphitization is performed under an argon atmosphere. Thus, graphitization is performed under different inert gas atmospheres at different temperatures to adapt to the reaction of the material at different temperature stages, thereby ensuring better quality of the resulting graphitized product. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG1 is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0023] As shown in Figure 1, the porous three-dimensional battery negative electrode material of the present invention is prepared from empty palm fruit bunches, and the porous three-dimensional battery negative electrode material has natural porosity. The porous three-dimensional battery negative electrode material is prepared from empty palm fruit bunches after oil extrusion.

[0024] The method for preparing the porous three-dimensional battery negative electrode material using empty palm fruit bunches comprises the following steps:

[0025] a. Collect empty palm fruit bunches as raw materials and crush the raw materials;

[0026] b. The crushed material is heated and smoldered to perform initial carbonization, wherein the heating temperature is 380℃~700℃;

[0027] c. After the initial carbonization, the material is heated to 1800℃~3000℃ and graphitized under an inert gas atmosphere;

[0028] d. After the material is graphitized, it is crushed to obtain a powder material with a particle size range of 200nm to 50μm;

[0029] e. Pre-lithiation or pre-sodiumization is performed by chemical vapor deposition to obtain the final porous three-dimensional battery negative electrode material.

[0030] More specifically, in step a, the raw materials are pulverized to a particle size of 1 mm to 200 mm. In step c, when the temperature is below 2000°C, graphitization is performed under a nitrogen atmosphere; when the temperature is above 2000°C, graphitization is performed under an argon atmosphere. In step d, the particle size of the powdered material obtained after pulverization is in the range of 500 nm to 50 μm. In step e, after pre-lithiation by chemical vapor deposition, a pre-siliconization step is also performed by chemical vapor deposition to obtain the final porous three-dimensional battery negative electrode material.

[0031] The present invention is further described below with reference to more specific embodiments.

[0032] Example 1: Preparation of porous three-dimensional lithium-ion battery negative electrode material

[0033] A method for preparing a porous three-dimensional lithium-ion battery negative electrode material using empty palm fruit bunches, the method comprising the following steps:

[0034] a. Collect 100KG~>5000KG of empty palm fruit bunches after oil squeezing as raw materials, and crush the raw materials to a particle size of 1mm~200mm;

[0035] b. The crushed material is heated and smoldered in a closed environment for initial carbonization, wherein the heating temperature is 380°C to 700°C. In this embodiment, the specific temperature is set to 550°C, the smoldering treatment time is 1h to 24h, and the carbonization depth is measured using a carbonization depth meter. When 90% carbonization is reached, heating is stopped and the material is removed after cooling;

[0036] c. After the material is initially carbonized, the temperature is raised to 1800°C to 3000°C and graphitized under an inert gas atmosphere. In this embodiment, when the temperature is lower than 2000°C, nitrogen is introduced so that the environment is in a nitrogen atmosphere for graphitization; when the temperature is higher than 2000°C, argon is introduced so that the environment is in an argon atmosphere for graphitization.

[0037] d. After the material is graphitized, the material is crushed to obtain a powder material having a particle size range of 200 nm to 50 μm; in this embodiment, the particle size range of the powder material obtained after crushing is 500 nm to 50 μm;

[0038] e. Performing a pre-lithiation treatment by chemical vapor deposition, and then performing a pre-siliconization treatment by chemical vapor deposition to obtain a final porous three-dimensional lithium-ion battery negative electrode material, wherein the porous three-dimensional lithium-ion battery negative electrode material has natural porosity. Here, the specific steps of performing the pre-lithiation treatment by chemical vapor deposition are:

[0039] 1. Surface activation: Place the graphitized material into the chemical vapor deposition equipment chamber and evacuate to 10 -4 torr, the chamber temperature is 25°C to 450°C; an argon / hydrogen mixed atmosphere is introduced with a ratio of 10:1 to 5 to control the chamber pressure at 1 to 30 mtorr. The argon / hydrogen mixed atmosphere is activated by plasma, and the plasma-activated argon / hydrogen mixed atmosphere and the graphitized material are activated on the surface for 5 minutes to 30 minutes.

[0040] 2. Pre-lithiation treatment: Maintaining the chamber pressure of 1 to 30 mtorr and the chamber temperature of 25°C to 450°C in step 1, the argon / hydrogen mixed atmosphere is changed to an argon / silicon-based lithium fluoride mixed atmosphere with a ratio of 10:1 to 5. The argon / silicon-based lithium fluoride mixed atmosphere is activated by plasma, and the plasma-activated argon / silicon-based lithium fluoride mixed atmosphere and the graphitized material are subjected to a surface pre-lithiation treatment for 5 minutes to 30 minutes.

[0041] The specific steps of performing pre-siliconization treatment by chemical vapor deposition are as follows:

[0042] The pre-siliconization treatment is a continuation of step 2 (pre-lithiation treatment) described above. The chamber pressure of 1 to 30 mtorr and the chamber temperature of 25°C to 450°C in step 1 are maintained, and the argon / silicon-based lithium fluoride mixed atmosphere is changed to a silane / hydrogen mixed atmosphere in a ratio of 1 to 5:10. The silane / hydrogen mixed atmosphere is activated by plasma, and the surface of the graphitized material is subjected to a pre-siliconization treatment for 1 to 10 minutes.

[0043] The porous three-dimensional lithium-ion battery anode material prepared above was used in lithium-ion battery testing. The parameters of the lithium-ion battery used were: battery capacity: 50AH; nominal voltage: 3.2V; battery dimensions: (115±0.2)*(36.2±0.2)*(191.0±0.5mm)(W*T*H). After testing, the final performance of the lithium-ion battery using the porous three-dimensional lithium-ion battery anode material prepared by the above method is shown in Table 1:

[0044] Table 1 Final performance of lithium-ion batteries

[0045] It can be seen that after the porous three-dimensional lithium ion battery negative electrode material prepared by the method of the present invention is applied to a lithium ion battery, the performance of the prepared lithium ion battery is better and can meet the requirements of the existing technology for lithium ion batteries.

[0046] Example 2: Preparation of porous three-dimensional sodium ion battery negative electrode material

[0047] A method for preparing a porous three-dimensional sodium ion battery negative electrode material using empty palm fruit bunches, the method comprising the following steps:

[0048] a. Collect 100KG~>5000KG of empty palm fruit bunches after oil squeezing as raw materials, and crush the raw materials to a particle size of 1mm~200mm;

[0049] b. The crushed material is heated and smoldered in a closed environment for initial carbonization, wherein the heating temperature is 380°C to 700°C. In this embodiment, the specific temperature is set to 550°C, the smoldering treatment time is 1h to 24h, and the carbonization depth is measured using a carbonization depth meter. When 90% carbonization is reached, heating is stopped and the material is removed after cooling;

[0050] c. After the material is initially carbonized, the temperature is raised to 1800°C to 3000°C and graphitized under an inert gas atmosphere. In this embodiment, when the temperature is lower than 2000°C, nitrogen is introduced so that the environment is in a nitrogen atmosphere for graphitization; when the temperature is higher than 2000°C, argon is introduced so that the environment is in an argon atmosphere for graphitization.

[0051] d. After the material is graphitized, the material is crushed to obtain a powder material having a particle size range of 200 nm to 50 μm; in this embodiment, the particle size range of the powder material obtained after crushing is 500 nm to 50 μm;

[0052] e. Pre-sodium treatment is performed by chemical vapor deposition to obtain a final porous three-dimensional sodium ion battery negative electrode material, wherein the porous three-dimensional sodium ion battery negative electrode material has natural porosity. Here, the specific steps of performing pre-sodium treatment by chemical vapor deposition are:

[0053] 1. Surface activation: Place the graphitized material into the chemical vapor deposition equipment chamber and evacuate to 10 -4 The chamber temperature is below 25°C to 450°C, and an argon / hydrogen mixed atmosphere is introduced with a ratio of 10:1 to 5 to control the chamber pressure at 1 to 30 mtorr. The argon / hydrogen mixed atmosphere is activated by plasma, and the plasma-activated argon / hydrogen mixed atmosphere and the graphitized material are activated on the surface for 5 to 30 minutes.

[0054] 2. Pre-sodium treatment: Maintaining the chamber pressure of 1 to 30 mtorr and the chamber temperature of 25°C to 450°C in step 1 above, the argon / hydrogen mixed atmosphere is changed to an argon / disodium silicon fluoride mixed atmosphere with a ratio of 10:1 to 5. The argon / disodium silicon fluoride mixed atmosphere is activated by plasma, and the plasma-activated argon / disodium silicon fluoride mixed atmosphere and the graphitized material are subjected to a surface pre-lithiation treatment for 5 minutes to 30 minutes.

[0055] The porous three-dimensional sodium-ion battery anode material prepared above was used in sodium-ion battery testing. The parameters of the sodium-ion battery used were: battery capacity: 2.3AH; nominal voltage: 3.2V; battery size: 26650 (26*650mm). After testing, the final performance of the sodium-ion battery using the porous three-dimensional sodium-ion battery anode material prepared by the above method is shown in Table 2:

[0056] Table 2 Final performance of sodium ion batteries

[0057] It can be seen that after the porous three-dimensional sodium ion battery negative electrode material prepared by the method of the present invention is applied to the sodium ion battery, the performance of the prepared sodium ion battery is better and can meet the requirements of the existing technology for sodium ion batteries.

[0058] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A porous three-dimensional battery negative electrode material made from empty palm fruit bunches, characterized in that: The porous three-dimensional battery negative electrode material is prepared from empty palm fruit bunches, and the porous three-dimensional battery negative electrode material is naturally porous.

2. The porous three-dimensional battery negative electrode material according to claim 1, characterized in that: The porous three-dimensional battery negative electrode material is prepared from empty palm fruit bunches after oil extrusion.

3. A method for preparing the porous three-dimensional battery negative electrode material as claimed in claim 1, characterized in that: The method comprises the following steps: a. Collect empty palm fruit bunches as raw materials and crush the raw materials; b. The crushed material is heated and smoldered to carry out initial carbonization, wherein the heating temperature is 380℃~700℃; c. After the initial carbonization, the material is heated to 1800℃~3000℃ and graphitized in an inert gas atmosphere; d. After the material is graphitized, it is crushed to obtain a powder material with a particle size ranging from 200nm to 50μm; e. Pre-lithiation or pre-sodiumization is carried out by chemical vapor deposition to obtain the final porous three-dimensional battery negative electrode material.

4. The preparation method according to claim 3, characterized in that: In the step e, after pre-lithiation by chemical vapor deposition, a pre-siliconization step is also included by chemical vapor deposition to obtain the final porous three-dimensional battery negative electrode material.

5. The preparation method according to claim 3, characterized in that: In the step a, the raw material is crushed to a particle size of 1 mm to 200 mm.

6. The preparation method according to claim 3, characterized in that: In the step d, the particle size of the powdery material obtained after pulverization is in the range of 500 nm to 50 μm.

7. The preparation method according to claim 3, characterized in that: In the step c, when the temperature is lower than 2000° C., graphitization is performed in a nitrogen atmosphere; when the temperature is higher than 2000° C., graphitization is performed in an argon atmosphere.

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