Alloy-hard carbon composite particles, and methods of making and using the same

Abstract

The application discloses alloy-hard carbon composite particles, a preparation method and application thereof. The preparation method of the alloy-hard carbon composite particles comprises the following steps: 1) placing a bamboo in an oxygen-containing atmosphere to perform a pre-oxidation treatment, and obtaining a pre-oxidized bamboo; 2) crushing the pre-oxidized bamboo to obtain a pre-oxidized bamboo powder; 3) mixing the pre-oxidized bamboo powder and alloy powder to perform ball milling, and then placing the mixture in a protective atmosphere to perform carbonization, so that the alloy-hard carbon composite particles are obtained. The alloy-hard carbon composite particles are used as a negative electrode material of a sodium ion battery, and have the advantages of large specific capacity, good cycle stability, excellent electrochemical performance and the like, and the preparation method is simple, the production cost is low, and the alloy-hard carbon composite particles are suitable for large-scale industrial application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sodium ion batteries, in particular to an alloy-hard carbon composite particle and a preparation method and application thereof. BACKGROUND

[0002] At present, the demand for lithium ion batteries has reached an unprecedented scale, which is widely used in various electronic devices, new energy electric vehicles and military unmanned aerial vehicles and other fields, and firmly occupies the energy storage market. However, in view of the scarcity of lithium element resources, it is of great significance to develop alternative energy storage technology. Sodium and lithium belong to the same main group of elements, and their chemical properties are very similar. Sodium has the advantages of wide resource distribution, abundant source and low price, so sodium ion battery is a potential energy storage device that can replace lithium ion battery.

[0003] The working mechanism of sodium ion battery is similar to that of lithium ion battery, which also belongs to rocking chair type ion battery. The electrode material is one of the cores of the battery and is the most important in the research of the battery. At present, the negative electrode materials of sodium ion battery mainly include carbon-based materials, alloy materials, metal oxides / sulfides, titanium-based materials, etc. The research of carbon-based materials mainly focuses on graphite-based carbon materials and amorphous carbon materials, and according to the difficulty of graphitization, amorphous carbon materials can be divided into soft carbon materials and hard carbon materials. Hard carbon material has many advantages such as low sodium storage voltage and good cycle performance, and its industrialization has made rapid progress, becoming the most promising negative electrode material of sodium ion battery, but its specific capacity needs to be further improved. Alloy materials can obtain high specific capacity, but its first coulomb efficiency is usually not high, and the cycle stability is also poor. In summary, the existing negative electrode materials of sodium ion battery all have obvious defects, and it is difficult to fully meet the requirements of practical application.

[0004] Therefore, it is of great significance to develop a sodium ion battery negative electrode material with high specific capacity, good cycle stability and excellent electrochemical performance. SUMMARY

[0005] The purpose of the present application is to provide an alloy-hard carbon composite particle and a preparation method and application thereof.

[0006] The technical scheme adopted by the present application is:

[0007] A preparation method of an alloy-hard carbon composite particle comprises the following steps:

[0008] 1) Pre-oxidizing a bamboo in an oxygen-containing atmosphere to obtain a pre-oxidized bamboo;

[0009] 2) crushing the pre-oxidized bamboo to obtain a pre-oxidized bamboo powder;

[0010] 3) mixing the pre-oxidized bamboo powder and the alloy powder and ball-milling, and then carbonizing in a protective atmosphere to obtain the alloy-hard carbon composite particles.

[0011] Preferably, the oxygen-containing atmosphere in step 1) is an air atmosphere.

[0012] Preferably, the specific operation of the pre-oxidation treatment in step 1) is to control the heating rate to 2-4℃ / min to heat from room temperature to 350-450℃, and then to keep the temperature for 1-3h.

[0013] Preferably, the specific operation of the breaking in step 2) is to mix the pre-oxidized bamboo with ball milling beads with a diameter of 5-8mm at a ball-to-material ratio of 1:5-10 for coarse grinding, and then mix with ball milling beads with a diameter of 1-2mm at a ball-to-material ratio of 1:5-10 for fine grinding.

[0014] Preferably, the coarse grinding is performed at a ball mill speed of 500-700r / min, and the coarse grinding time is 12-24h.

[0015] Preferably, the fine grinding is performed at a ball mill speed of 500-700r / min, and the fine grinding time is 12-24h.

[0016] Preferably, the particle size of the pre-oxidized bamboo powder in step 2) is 5-8μm.

[0017] Preferably, the mass ratio of the pre-oxidized bamboo powder to the alloy powder in step 3) is 1:0.05-0.10.

[0018] Preferably, the alloy powder in step 3) comprises manganese, tin and nickel.

[0019] Further preferably, the alloy powder in step 3) is a manganese-tin-nickel alloy powder.

[0020] Preferably, the mass ratio of manganese, tin and nickel in the manganese-tin-nickel alloy powder is 1:0.5-2:1-5.

[0021] Preferably, the specific operation of the ball-milling in step 3) is to mix the pre-oxidized bamboo powder and the alloy powder with ball milling beads with a diameter of 5-8mm at a ball-to-material ratio of 1:5-10.

[0022] Preferably, the ball-milling is performed at a ball mill speed of 400-500r / min, and the ball-milling time is 6-12h.

[0023] Preferably, the protective atmosphere in step 3) is a nitrogen atmosphere or an argon atmosphere.

[0024] Preferably, the specific operation of carbonization in step 3) is to control the heating rate to 2-4 ℃ / min from room temperature to 1000-1400 ℃, and then keep the temperature for 1-3 h.

[0025] An alloy-hard carbon composite particle prepared by the above preparation method.

[0026] A sodium ion battery negative material comprising the above alloy-hard carbon composite particle.

[0027] A sodium ion battery comprising the above sodium ion battery negative material.

[0028] The alloy-hard carbon composite particle of the present application has the advantages of high specific capacity, good cycle stability, excellent electrochemical performance, etc. when used as a sodium ion battery negative material, and the preparation method is simple, the production cost is low, and it is suitable for large-scale industrial application.

[0029] Specifically:

[0030] 1) The alloy-hard carbon composite particle of the present application belongs to alloy-doped hard carbon material, which not only improves the specific capacity of the hard carbon material, but also relieves the volume expansion of the alloy, improves the cycle performance, and has excellent electrochemical performance.

[0031] 2) The present application uses pre-oxidized bamboo and combines it with alloy for ball milling, which makes the hard carbon material peel off under the action of shear force, and partially cross-link with the surface of the alloy particle at high speed and high temperature, forming an irregular coating structure, which has the advantage of uniform doping. This structure provides a synergistic effect to reduce stress, adapt to large volume changes, can prevent material particles from aggregating, and can promote the transfer of electrons and electrolyte during long-term cycling. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 SEM image of the alloy-hard carbon composite particle of Example 1.

[0033] Figure 2 Cycle performance test result graph of the sodium ion half battery made of the alloy-hard carbon composite particle of Example 1-3.

[0034] Figure 3 Cycle performance test result graph of the sodium ion half battery made of the alloy-hard carbon composite particle of Example 3 and Example 4.

[0035] Figure 4 Cycle performance test result graph of the sodium ion half battery made of the alloy-hard carbon composite particle of Example 1 and the hard carbon particle of Comparative Example 1.

[0036] Figure 5The graph shows the cycle performance test results of sodium-ion half-cells made from alloy-hard carbon composite particles of Example 1 and alloy powder-hard carbon particle blends of Comparative Example 2. Detailed Implementation

[0037] The present invention will be further explained and described below with reference to specific embodiments.

[0038] Example 1:

[0039] An alloy-hard carbon composite particle is prepared by the following method:

[0040] 1) Place the bamboo in a muffle furnace and heat it from room temperature to 300°C in an air atmosphere at a heating rate of 3°C / min, and then keep it at that temperature for 2 hours to obtain pre-oxidized bamboo.

[0041] 2) Mix the pre-oxidized bamboo with 5mm diameter grinding balls at a ball-to-material ratio of 1:5 and ball mill at a speed of 580r / min for 12h. Then mix it with 1mm diameter grinding balls at a ball-to-material ratio of 1:10 and ball mill at a speed of 580r / min for 12h to obtain pre-oxidized bamboo powder (particle size of 5μm~8μm).

[0042] 3) Pre-oxidized bamboo powder and manganese-tin-nickel alloy powder (manganese, tin and nickel in a mass ratio of 1:0.5:3) are mixed with 8mm diameter ball milling beads at a ball-to-material ratio of 1:5 and the mass ratio of pre-oxidized bamboo powder to manganese-tin-nickel alloy powder is 1:0.05. The mixture is ball-milled for 6 hours at a speed of 400 r / min. The mixture obtained from the ball milling is then loaded into a ceramic boat and placed in a tube furnace. The temperature is increased from room temperature to 1000℃ at a heating rate of 3℃ / min in a nitrogen atmosphere and then held for 2 hours to obtain alloy-hard carbon composite particles.

[0043] The scanning electron microscope (SEM) image of the alloy-hard carbon composite particles in this embodiment is shown below. Figure 1 As shown.

[0044] Depend on Figure 1 It can be seen that the alloy-hard carbon composite particles prepared in Example 1 have a fragmented structure, uniform size distribution, and a particle size of 5μm to 8μm.

[0045] Example 2:

[0046] An alloy-hard carbon composite particle is prepared by the following method:

[0047] 1) Place the bamboo in a muffle furnace and heat it from room temperature to 300°C in an air atmosphere at a heating rate of 3°C / min, and then keep it at that temperature for 2 hours to obtain pre-oxidized bamboo.

[0048] 2) The pre-oxidized bamboo is mixed with ball milling beads with a diameter of 5 mm at a ball-to-material ratio of 1:5, and ball-milled at a speed of 580 r / min for 12 h. Then the pre-oxidized bamboo is mixed with ball milling beads with a diameter of 1 mm at a ball-to-material ratio of 1:10, and ball-milled at a speed of 580 r / min for 12 h to obtain pre-oxidized bamboo powder (with a particle size of 5 μm-8 μm);

[0049] 3) The pre-oxidized bamboo powder and manganese-tin-nickel alloy powder (with a mass ratio of manganese, tin and nickel of 1:0.5:3) are mixed with ball milling beads with a diameter of 8 mm at a ball-to-material ratio of 1:5, and the mass ratio of the pre-oxidized bamboo powder to the manganese-tin-nickel alloy powder is 1:0.05. The mixture is ball-milled at a speed of 400 r / min for 6 h. Then the ball-milled mixture is loaded into a porcelain boat and placed in a tube furnace, and heated from room temperature to 1200 °C at a heating rate of 3 °C / min in a nitrogen atmosphere, and then kept at 1200 °C for 2 h to obtain alloy-hard carbon composite particles.

[0050] Example 3:

[0051] An alloy-hard carbon composite particle is prepared by the following method:

[0052] 1) The bamboo is placed in a muffle furnace, and heated from room temperature to 300 °C at a heating rate of 3 °C / min in an air atmosphere, and then kept at 300 °C for 2 h to obtain pre-oxidized bamboo;

[0053] 2) The pre-oxidized bamboo is mixed with ball milling beads with a diameter of 5 mm at a ball-to-material ratio of 1:5, and ball-milled at a speed of 580 r / min for 12 h. Then the pre-oxidized bamboo is mixed with ball milling beads with a diameter of 1 mm at a ball-to-material ratio of 1:10, and ball-milled at a speed of 580 r / min for 12 h to obtain pre-oxidized bamboo powder (with a particle size of 5 μm-8 μm);

[0054] 3) The pre-oxidized bamboo powder and manganese-tin-nickel alloy powder (with a mass ratio of manganese, tin and nickel of 1:0.5:3) are mixed with ball milling beads with a diameter of 8 mm at a ball-to-material ratio of 1:5, and the mass ratio of the pre-oxidized bamboo powder to the manganese-tin-nickel alloy powder is 1:0.05. The mixture is ball-milled at a speed of 400 r / min for 6 h. Then the ball-milled mixture is loaded into a porcelain boat and placed in a tube furnace, and heated from room temperature to 1400 °C at a heating rate of 3 °C / min in a nitrogen atmosphere, and then kept at 1400 °C for 2 h to obtain alloy-hard carbon composite particles.

[0055] Example 4:

[0056] An alloy-hard carbon composite particle is prepared by the following method:

[0057] 1) Bamboo was put into a muffle furnace, and heated from room temperature to 300℃ at a heating rate of 3℃ / min in air atmosphere, and then kept for 2h to obtain pre-oxidized bamboo;

[0058] 2) The pre-oxidized bamboo was mixed with ball milling beads with a diameter of 5mm at a ball-to-material ratio of 1:5, and ball-milled at a speed of 580r / min for 12h. Then the ball-milling product was mixed with ball milling beads with a diameter of 1mm at a ball-to-material ratio of 1:10, and ball-milled at a speed of 580r / min for 12h to obtain pre-oxidized bamboo powder (particle size of 5μm-8μm);

[0059] 3) The pre-oxidized bamboo powder and manganese-tin-nickel alloy powder (mass ratio of manganese, tin and nickel is 1:0.5:3) were mixed with ball milling beads with a diameter of 8mm at a ball-to-material ratio of 1:5, and the mass ratio of pre-oxidized bamboo powder to manganese-tin-nickel alloy powder was 1:0.10. The mixture was ball-milled at a speed of 400r / min for 6h. Then the ball-milling product was put into a porcelain boat and placed into a tube furnace, and heated from room temperature to 1400℃ at a heating rate of 3℃ / min in nitrogen atmosphere, and then kept for 2h to obtain alloy-hard carbon composite particles.

[0060] Comparative Example 1:

[0061] A hard carbon particle was prepared by the following method:

[0062] 1) Bamboo was put into a muffle furnace, and heated from room temperature to 300℃ at a heating rate of 3℃ / min in air atmosphere, and then kept for 2h to obtain pre-oxidized bamboo;

[0063] 2) The pre-oxidized bamboo was mixed with ball milling beads with a diameter of 5mm at a ball-to-material ratio of 1:5, and ball-milled at a speed of 580r / min for 12h. Then the ball-milling product was mixed with ball milling beads with a diameter of 1mm at a ball-to-material ratio of 1:10, and ball-milled at a speed of 580r / min for 12h to obtain pre-oxidized bamboo powder (particle size of 5μm-8μm);

[0064] 3) The pre-oxidized bamboo powder was put into a porcelain boat and placed into a tube furnace, and heated from room temperature to 1000℃ at a heating rate of 3℃ / min in nitrogen atmosphere, and then kept for 2h to obtain hard carbon particles.

[0065] Comparative Example 2:

[0066] An alloy powder-hard carbon particle blend was prepared by the following method:

[0067] 1) Bamboo was put into a muffle furnace, and heated from room temperature to 300℃ at a heating rate of 3℃ / min in air atmosphere, and then kept for 2h to obtain pre-oxidized bamboo;

[0068] 2) The pre-oxidized bamboo was mixed with ball milling beads with a diameter of 5 mm at a ball-to-material ratio of 1:5, and ball-milled at a speed of 580 r / min for 12 h. Then, the pre-oxidized bamboo was mixed with ball milling beads with a diameter of 1 mm at a ball-to-material ratio of 1:10, and ball-milled at a speed of 580 r / min for 12 h, to obtain pre-oxidized bamboo powder (with a particle size of 5 μm-8 μm);

[0069] 3) The pre-oxidized bamboo powder was loaded into a porcelain boat and placed in a tube furnace. The temperature was raised to 1000℃ at a rate of 3℃ / min under a nitrogen atmosphere, and then maintained for 2 h, to obtain hard carbon particles;

[0070] 4) The hard carbon particles and manganese-tin-nickel alloy powder (with a mass ratio of manganese, tin and nickel of 1:0.5:3) were mixed at a mass ratio of 1:0.05 to obtain an alloy powder-hard carbon particle blend.

[0071] Performance test:

[0072] The alloy-hard carbon composite particles of Examples 1-4, the hard carbon particles of Comparative Example 1 and the alloy powder-hard carbon particle blend of Comparative Example 2 were used as negative electrode materials to prepare sodium ion half-batteries (the preparation process of the sodium ion half-batteries was as follows: a, the alloy-hard carbon composite particles / hard carbon particles / alloy powder-hard carbon particle blend, a conductive agent super P and a binder PVDF were mixed at a mass ratio of 8:1:1, and then fully ground. NMP was slowly added during the grinding process to obtain an electrode slurry; b, the electrode slurry was coated on the surface of a copper foil current collector, and then vacuum dried, punched and pressed to obtain a negative electrode sheet; c, the negative electrode sheet was placed in a glove box, and then combined with a GF / C glass fiber membrane (separator), a metal sodium sheet (counter electrode), an electrolyte and positive and negative electrode shells in the glove box to form a CR2016 button cell. The electrolyte was a 1 mol / L NaClO4 solution, and the solvent in the electrolyte was composed of EC and DEC at a volume ratio of 1:1. The cycle performance test was carried out at a current density of 0.1 A / g and a voltage range of 0.01 V-3 V (the cycle number was 110 times). The cycle performance test results of the sodium ion half-batteries using the alloy-hard carbon composite particles of Examples 1-3 as negative electrode materials are shown in Figure 2 The cycle performance test results of the sodium ion half-batteries using the alloy-hard carbon composite particles of Examples 3 and 4 as negative electrode materials are shown in Figure 3 The cycle performance test results of the sodium ion half-batteries using the alloy-hard carbon composite particles of Example 1 and the hard carbon particles of Comparative Example 1 as negative electrode materials are shown in Figure 4 The cycle performance test results of the sodium ion half-batteries using the alloy-hard carbon composite particles of Example 1 and the alloy powder-hard carbon particle blend of Comparative Example 2 as negative electrode materials are shown in Figure 5 The test results are shown in the following table:

[0073] Table 1 Performance test data of sodium ion half-batteries

[0074] Serial number Carbonization temperature (°C) Reversible specific capacity (mAh / g) Capacity retention rate (%) Example 1 1000 393.71 79.27 Example 2 1200 404.64 83.23 Example 3 1400 461.43 90.11 Example 4 1400 486.24 84.38 Comparative Example 1 1000 262.47 60.47 Comparative Example 2 1000 334.95 54.42

[0075] As can be seen from Table 1, the reversible specific capacity and the capacity retention rate after cycling of the sodium ion half-batteries made of the alloy-hard carbon composite particles of Examples 1-4 as the negative electrode material are significantly improved compared with the sodium ion half-batteries made of the hard carbon particles of Comparative Example 1 and the alloy powder-hard carbon particle blend of Comparative Example 2 as the negative electrode material, and increasing the alloy doping amount can also improve the specific capacity of the sodium ion half-batteries made of the alloy-hard carbon composite particles as the negative electrode material, but will cause the capacity retention rate to decrease.

[0076] As can be seen from Table 1, Figure 2 the sodium ion half-batteries made of the alloy-hard carbon composite particles of Example 3 as the negative electrode material not only have higher reversible specific capacity, but also have better cycling stability compared with the sodium ion half-batteries made of the alloy-hard carbon composite particles of Examples 1 and 2 as the negative electrode material, indicating that the carbonization temperature is crucial.

[0077] As can be seen from Table 1, Figure 3 the sodium ion half-batteries made of the alloy-hard carbon composite particles of Example 4 as the negative electrode material have higher reversible specific capacity, but have poorer cycling stability compared with the sodium ion half-batteries made of the alloy-hard carbon composite particles of Example 3 as the negative electrode material, indicating that increasing the alloy powder doping amount can improve the specific capacity of the sodium ion half-batteries made of the alloy-hard carbon composite particles as the negative electrode material, but will cause the cycling stability to deteriorate.

[0078] As can be seen from Table 1, Figure 4 the reversible specific capacity and the capacity retention rate after cycling of the sodium ion half-batteries made of the alloy-hard carbon composite particles of Example 1 as the negative electrode material are significantly improved compared with the sodium ion half-batteries made of the hard carbon particles of Comparative Example 1 as the negative electrode material, indicating that the alloy powder doping greatly improves the specific capacity and the cycling stability of the sodium ion half-batteries.

[0079] As can be seen from Table 1, Figure 5 the capacity retention rate after cycling of the sodium ion half-batteries made of the alloy powder-hard carbon particle blend of Comparative Example 2 as the negative electrode material is much lower compared with the sodium ion half-batteries made of the alloy-hard carbon composite particles of Example 1 as the negative electrode material, indicating that the simple mixing of the alloy powder and the hard carbon particles cannot play a role in relieving the volume expansion.

[0080] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A method for preparing alloy-hard carbon composite particles, characterized in that, Includes the following steps: 1) Bamboo is placed in an oxygen-containing atmosphere for pre-oxidation treatment to obtain pre-oxidized bamboo; 2) The pre-oxidized bamboo is crushed to obtain pre-oxidized bamboo powder; 3) Mix the pre-oxidized bamboo powder and alloy powder, ball mill them, and then place them in a protective atmosphere for carbonization to obtain alloy-hard carbon composite particles. The specific operation of the pre-oxidation treatment in step 1) is as follows: first, control the heating rate to 2℃ / min~4℃ / min to raise the temperature from room temperature to 350℃~450℃, and then keep it at that temperature for 1h~3h; Step 3) The specific operation of ball milling is as follows: pre-oxidized bamboo powder and alloy powder are mixed with ball milling beads with a diameter of 5mm to 8mm at a ball-to-material ratio of 1:5 to 10 and then ball milled. The ball milling is carried out at a ball mill speed of 400 r / min to 500 r / min, and the ball milling time is 6 h to 12 h. Step 3) The specific operation of carbonization is as follows: first, control the heating rate to 2℃ / min~4℃ / min to raise the temperature from room temperature to 1000℃~1400℃, and then keep it at that temperature for 1h~3h.

2. The preparation method according to claim 1, characterized in that: Step 2) The specific operation of crushing is as follows: First, the pre-oxidized bamboo is mixed with grinding balls with a diameter of 5mm to 8mm at a ball-to-material ratio of 1:5 to 10 for coarse grinding, and then mixed with grinding balls with a diameter of 1mm to 2mm at a ball-to-material ratio of 1:5 to 10 for fine grinding.

3. The preparation method according to claim 1 or 2, characterized in that: Step 2) The pre-oxidized bamboo powder has a particle size of 5μm to 8μm.

4. The preparation method according to claim 1, characterized in that: Step 3) The mass ratio of the pre-oxidized bamboo powder to the alloy powder is 1:0.05 to 0.

10.

5. The preparation method according to claim 1 or 4, characterized in that: Step 3) The alloy powder consists of manganese, tin and nickel.

6. An alloy-hard carbon composite particle, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 5.

7. A sodium-ion battery anode material, characterized in that, It includes the alloy-hard carbon composite particles as described in claim 6.

8. A sodium-ion battery, characterized in that, It includes the sodium-ion battery anode material as described in claim 7.

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