Hard carbon negative electrode material, preparation method and application thereof, and battery containing same

Abstract

The application discloses a kind of hard carbon negative materials and its preparation method and application, contain its battery, it includes the following steps: carbon source material powder is mixed with foaming agent and is foamed once, obtain hard carbon precursor A;The foaming agent is the foaming agent of carbon atom number ≥3;The hard carbon precursor A is mixed with resin solution and is foamed twice, obtain hard carbon precursor B;The viscosity of the resin solution is 50-500cP, the carbon content of the resin solution is 1-40%;The hard carbon precursor B is heat treated, obtain hard carbon negative material.The hard carbon negative material particle of the application is more uniform inside pore structure, is used for battery performance excellent, first charge-discharge specific capacity is high, to electrolyte wetting performance is good, with higher first efficiency, expansion is small, cycle capacity is strong, suitable for mass production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery negative electrode materials, in particular to a hard carbon negative electrode material, a preparation method and application thereof, and a battery containing the same. BACKGROUND

[0002] There are many ways to adjust the pore structure in the preparation method of the prior art hard carbon material, and the regulation of the pore structure of the material has become a key indicator of process control. The currently used method has poor environmental friendliness, harsh production conditions, poor process control ability, reduces the service life of processing equipment, and has large specific surface area of the material, poor material uniformity, large batch difference of the product, and great influence on subsequent battery processing, which is also a problem urgently to be solved in the field of hard carbon materials at present. Through improvement of the hard carbon material by a carbon source and other high molecular materials, combined with composite foaming technology, the processing cost is reduced, the production line equipment is optimized, and the internal structure of the hard carbon material is modified and supplemented, so that the hard carbon material has excellent first charge and discharge efficiency, low specific surface area, good cycle performance and high safety.

[0003] Chinese patent application CN115676802A discloses dissolving or dispersing a carbon source in water, then immersing a high molecular foaming material in the carbon source mixture for impregnation treatment, performing polycondensation treatment, grinding the solid into powder, introducing an organic gas, and performing chemical vapor deposition treatment on the powder. In this method, the carbon source is directly mixed and impregnated with the foaming agent resin, and the carbon source and the resin cannot completely react during the polycondensation reaction, which has an inhibitory effect, and the two interfere with each other, resulting in poor consistency of the pore structure, a large number of invalid pores, more free carbon formed during vapor deposition, more electrolyte consumed when forming the SEI film, poor first charge and discharge efficiency of the material, and influence on the rapid intercalation and deintercalation of ions, cycle life and processing performance of the front end of the battery. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the defects in the prior art method of modifying the internal structure of the hard carbon negative electrode material, such as poor uniformity of the pore structure formed, poor first charge and discharge efficiency of the material, and influence on the rapid intercalation and deintercalation of ions, cycle life and processing performance of the front end of the battery, and to provide a hard carbon negative electrode material, a preparation method and application thereof, and a battery containing the same. The hard carbon negative electrode material prepared by the present application has more uniform internal pore structure, excellent battery performance, high first charge and discharge specific capacity, good wettability with electrolyte, high first efficiency, small expansion, strong cycle capacity, and is suitable for mass production.

[0005] The present application solves the above technical problems by the following technical scheme:

[0006] The present application discloses a preparation method of a hard carbon negative electrode material, comprising the following steps:

[0007] S1. mixing the carbon source material powder with a foaming agent to perform primary foaming to obtain a hard carbon precursor A; the foaming agent is a foaming agent with carbon atom number ≥ 3;

[0008] S2. mixing the hard carbon precursor A with a resin solution to perform secondary foaming to obtain a hard carbon precursor B; the viscosity of the resin solution is 50-500 cP, the residual carbon content of the resin solution is 1-40%; the residual carbon content refers to the carbon content of the remaining organic matter after heat treatment, accounting for the mass percentage of the total organic matter;

[0009] S3. heat treating the hard carbon precursor B to obtain a hard carbon negative electrode material.

[0010] In the present application, the determination method of the residual carbon content can be SH / T0170 "Residual Carbon Determination Value (Electric Furnace Method)".

[0011] As preferred, in step S1, the carbon source material powder is obtained by pre-treatment of the carbon source material; the pre-treatment can be a conventional treatment in the art, preferably crushing or pulverizing; the pre-treatment device is preferably airflow mill, mechanical mill, roller mill or ball mill.

[0012] As preferred, in step S1, the D50 of the carbon source material powder is preferably 1-40 μm, for example 10 μm.

[0013] As preferred, the carbon source material is one or a combination of at least two of pitch, glucose, sucrose, starch and cellulose.

[0014] As preferred, the foaming agent is a foaming agent with 3≤ carbon atom number ≤ 10;

[0015] The foaming agent is preferably one or several of sec-butyl acetate, adiponitrile, polyisobutylene, linalool, methyl pinacolate, piperylene, cyclopentadiene, isoprene.

[0016] In the present application, a foaming agent with relatively mild properties can be selected in the primary foaming, and the by-products generated in the foaming process are less, which is more environmentally friendly.

[0017] As preferred, the mass ratio of the carbon source material powder to the foaming agent is 100: (0.1-30), for example 100:8 or 100:15.

[0018] As preferred, in step S1, the temperature of the primary foaming is 100-700℃, for example 500℃ or 600℃.

[0019] As preferred, the time of the primary foaming is 0.5-6h, for example 4h.

[0020] As preferred, the atmosphere of the primary foaming is one or more of air, ammonia, oxygen and ozone.

[0021] As preferred, the device of the primary foaming is a muffle furnace, an electric resistance furnace, a tube furnace or a roller furnace.

[0022] As preferred, the primary foaming further comprises dispersion kneading.

[0023] As preferred, the device of the dispersion kneading is a kneader, a planetary dispersion mixer, a VC mixer, a double-pot mixer or a vertical mixer.

[0024] As preferred, the speed of the dispersion kneading is 100-150 rpm, for example 120 rpm.

[0025] As preferred, the time of the dispersion kneading is 0.5-2 h, for example 1 h.

[0026] As preferred, the primary foaming further comprises crushing.

[0027] In an embodiment, the hard carbon precursor A comprises a disordered pore structure.

[0028] As preferred, in step S2, the method of preparing the resin solution is adding the resin into a solvent for dilution and dispersion.

[0029] As preferred, the mass ratio of the solvent to the resin is 100:(1-60), for example 100:30 or 100:60.

[0030] As preferred, the solvent comprises one or a combination of at least two of acetone, diethyl ether, ethanol, styrene, fatty acid ester, methacrylic ester, tetrahydrofuran and deionized water.

[0031] As preferred, the resin comprises a thermosetting resin and / or a thermoplastic resin, for example a phenolic resin.

[0032] As preferred, the time of the dilution and dispersion is 0.5-4 h, for example 2 h.

[0033] As preferred, in step S2, the mass ratio of the hard carbon precursor A to the resin solution is 100:(0.1-40), for example 100:12, 100:20 or 100:30.

[0034] As preferred, in step S2, the secondary foaming is mixing and dispersing the hard carbon precursor A with the resin solution, foaming and coating, and crushing to obtain the hard carbon precursor B.

[0035] As preferred, the viscosity of the resin solution is 237-292 cP.

[0036] As preferred, the carbon residue content of the resin solution is 9-15%.

[0037] As preferred, in step S2, the device for the secondary foaming is a ribbon blender, an electric heating mixer or a horizontal kettle.

[0038] As preferred, the temperature for the secondary foaming is 50-400℃.

[0039] As preferred, the holding time for the secondary foaming is 0.5-8h, for example 2h.

[0040] As preferred, the temperature control mode for the secondary foaming is constant temperature, temperature rising or temperature rising-constant temperature interval;

[0041] When the temperature rising mode is adopted, the rate of the temperature rising is preferably 1-10℃ / min.

[0042] As preferred, the secondary foaming adopts a segmented temperature control mode, which includes a first temperature control and a second temperature control in sequence; the temperature of the second temperature control is higher than that of the first temperature control.

[0043] The end temperature of the first temperature control is preferably 100-150℃, for example 100℃ or 150℃; the rate of the temperature rising of the first temperature control is preferably 2-4℃ / min, for example 2℃ / min or 4℃ / min.

[0044] The end temperature of the second temperature control is preferably 300-400℃, for example 300℃ or 400℃; the rate of the temperature rising of the second temperature control is preferably 2-4℃ / min, for example 2℃ / min or 4℃ / min.

[0045] As preferred, the atmosphere for the secondary foaming includes an inert atmosphere and / or an oxidative atmosphere;

[0046] As preferred, the inert atmosphere is argon or nitrogen;

[0047] As preferred, the oxidative atmosphere is air, oxygen or ozone;

[0048] As preferred, the D50 of the hard carbon precursor B is 1-20μm, for example 8μm.

[0049] As preferred, in step S3, the heat treatment is programmed automatic temperature rising.

[0050] As preferred, the temperature for the heat treatment is 900-1400℃.

[0051] As preferred, the holding time for the heat treatment is 0.5-8h, for example 5h or 6h.

[0052] Preferably, the heat treatment is performed in a stepwise temperature control mode, which comprises a first temperature control step and a second temperature control step, and the temperature of the second temperature control step is higher than that of the first temperature control step.

[0053] Preferably, the terminal temperature of the first temperature control step is 400-600℃, for example 400℃ or 600℃.

[0054] Preferably, the temperature increasing rate of the first temperature control step is 2-4℃ / min, for example 3℃ / min.

[0055] Preferably, the holding time of the first temperature control step is 1-2h, for example 1h or 2h.

[0056] Preferably, the terminal temperature of the second temperature control step is 1000-1300℃, for example 1000℃ or 1300℃.

[0057] Preferably, the temperature increasing rate of the second temperature control step is 1-3℃ / min, for example 2℃ / min.

[0058] Preferably, the holding time of the second temperature control step is 3-5h, for example 4h.

[0059] In the present application, the heat treatment is mainly used for pyrolysis reaction, to remove nitrogen, oxygen, metal and other impurities in the hard carbon precursor B, and to stabilize the structure of the hard carbon material.

[0060] Preferably, the heat treatment is performed in a reducing atmosphere and / or an inert atmosphere.

[0061] Preferably, the reducing atmosphere is a combination of one or more of ammonia, hydrogen and argon.

[0062] Preferably, the inert atmosphere is argon and / or nitrogen.

[0063] Preferably, the heat treatment device is a temperature-programmed holding device, and is preferably a box furnace, a tube furnace, a roller kiln, a push plate kiln, a tunnel kiln or a vacuum furnace.

[0064] The present application also provides a hard carbon negative electrode material prepared by the above method.

[0065] Preferably, the (002) interlayer spacing of the hard carbon negative electrode material is 0.379-0.395nm, for example 0.395nm, 0.391nm, 0.394nm or 0.390nm.

[0066] Preferably, the pore size distribution curve of the hard carbon negative electrode material has characteristic peaks in the pore size ranges of 0.5-0.6nm and 0.8-0.9nm.

[0067] The application also provides an application of the aforementioned hard carbon negative material in a battery, in particular in a lithium ion or sodium ion battery.

[0068] The application also provides a battery containing the aforementioned hard carbon negative material, which can be a lithium ion or sodium ion battery.

[0069] On the basis of common sense in the art, the above-mentioned preferred conditions can be combined arbitrarily, i.e., to obtain each preferred example of the application. It should be noted that due to technological development, the best embodiment can have performance beyond the test results of the application.

[0070] The reagents and raw materials used in the application are commercially available.

[0071] The positive progress effect of the application is that:

[0072] (1) The raw materials of the application are widely available and low in price, and the processing process does not discharge toxic and harmful substances, reduces carbon emissions, helps green development, has strong processability, and has small equipment wear. It is beneficial to commercialize batch use at the product end.

[0073] (2) The hard carbon precursor prepared by the application can be directly subjected to subsequent carbonization treatment, fully utilizing the intermediate product, and the obtained precursor forms amorphous carbon as activated carbon, without generating unqualified products, which is beneficial to continuous processing.

[0074] (3) The application utilizes twice foaming technology and good surface tension of liquid, the first time to form more disordered pore structure, the second time to modify the foaming defects formed in the first time inside the particles and form secondary pore structure on the surface, so that the pore structure of the hard carbon negative material is uniformly distributed.

[0075] (4) The hard carbon material carbon prepared by the application has good structure, adjusts mesopores and macropores, forms more micropore structure, forms a more beneficial lithium storage and sodium storage interlayer spacing, and is used in ion batteries. The ion battery has high first charge-discharge specific capacity, good electrolyte wetting performance, consumes less electrolyte after SEI film formation, has high first efficiency, small expansion, and strong cycle capacity. BRIEF DESCRIPTION OF DRAWINGS

[0076] Figure 1 The pore size distribution diagram of the hard carbon negative material of Example 1 of the application.

[0077] Figure 2 The XRD full spectrum diagram of the hard carbon negative material of Example 1 of the application. DETAILED DESCRIPTION

[0078] The application will be further described below by way of examples, but the application is not limited in the scope of the examples.

[0079] The reagents and raw materials used in the following examples, such as pitch, are commercially available.

[0080] The viscosity of the phenolic resin solution in the following examples is tested at 40°C, and the testing method is as follows: after preheating the equipment, 500 mL of sample is taken in a flat-bottomed beaker, a No. 1 rotor is selected, the rotor is soaked for 3 min, the speed is adjusted to 30 rpm, and the temperature is adjusted to 40°C before starting the measurement. Each measurement is between 10% and 100%, and the average of two measurements is taken.

[0081] The testing method for the carbon residue content in the following examples refers to SH / T0170 "Carbon Residue Determination (Electrical Furnace Method)".

[0082] Example 1

[0083] 1. Take 5 kg of pitch, use a mechanical mill to crush to D50 of 10 μm.

[0084] 2. Take 1 kg of crushed pitch and 0.08 kg of cyclopentadiene in a planetary dispersion mixer, stir at 120 rpm for 1 hour, and knead thoroughly. After cooling, the material is discharged and placed in a resistance furnace, air is introduced, and the equipment is heated to 500°C, and kept at this temperature for 4 hours. After cooling, the material is discharged and crushed to D50 of 8 μm using a mechanical mill to obtain hard carbon precursor A containing disordered pore structure.

[0085] 3. Take 0.3 kg of phenolic resin and place it in 1 kg of ethanol, stir continuously for 2 hours, and dilute and disperse thoroughly to obtain a phenolic resin solution with a viscosity of 292 cP and a carbon residue content of 15%.

[0086] 4. Take 0.5 kg of hard carbon precursor A and 0.1 kg of the above phenolic resin solution and place them in a planetary dispersion mixer, stir at 120 rpm for 1 hour, and knead thoroughly to obtain a composite.

[0087] 5. Transfer the composite to an electric heating mixer, heat to 150°C at a rate of 4°C / min, then heat to 300°C at a rate of 2°C / min, and keep the temperature constant for 2 hours. After the whole process, the material is selected to be in a nitrogen atmosphere to obtain hard carbon precursor B.

[0088] 6. Place the hard carbon precursor B in a tube furnace for high-temperature heat treatment, heat to 600°C at a rate of 3°C / min in a nitrogen atmosphere, keep the temperature constant for 1 hour, heat to 1300°C at a rate of 2°C / min, and keep the temperature constant for 4 hours. After cooling to room temperature, the material is discharged to obtain a hard carbon negative electrode material.

[0089] Example 2

[0090] 1. Take 5 kg of pitch, use a mechanical mill to crush to D50 of 10 μm.

[0091] 2. Take 1 kg of crushed asphalt and 0.15 kg of cyclopentadiene into a planetary dispersion mixer, stir at 120 rpm for 1 hour, and knead thoroughly. Put the mixture into a resistance furnace, pass air through, heat the equipment to 600°C, and keep the temperature constant for 4 hours. After cooling, use a mechanical mill to crush the mixture to D50 of 8 μm, and obtain hard carbon precursor A with disordered pore structure.

[0092] 3. Take 0.3 kg of phenolic resin, put it into 1 kg of ethanol, and stir for 2 hours, to dilute and disperse the phenolic resin thoroughly. Obtain a phenolic resin solution with a viscosity of 237 cP and a carbon residue content of 9%.

[0093] 4. Take 0.5 kg of hard carbon precursor A and 0.15 kg of the above resin solution, put them into a planetary dispersion mixer, stir at 120 rpm for 2 hours, and knead thoroughly, to obtain a composite.

[0094] 5. Transfer the composite to an electric heating mixer, heat to 150°C at a rate of 4°C / min, then heat to 300°C at a rate of 2°C / min, keep the temperature constant for 2 hours, and use nitrogen as the atmosphere during the whole process, to obtain hard carbon precursor B.

[0095] 6. Put hard carbon precursor B into a tube furnace, heat-treat it at high temperature in a nitrogen atmosphere, heat to 600°C at a rate of 3°C / min, keep the temperature constant for 1 hour, heat to 1300°C at a rate of 2°C / min, keep the temperature constant for 4 hours, and then cool to room temperature, to obtain hard carbon negative electrode material.

[0096] Example 3

[0097] 1. Take 5 kg of asphalt, and use a mechanical mill to crush it to D50 of 10 μm.

[0098] 2. Take 1 kg of crushed asphalt and 0.08 kg of cyclopentadiene, put them into a planetary dispersion mixer, stir at 120 rpm for 1 hour, and knead thoroughly. Put the mixture into a resistance furnace, pass air through, heat the equipment to 500°C, and keep the temperature constant for 4 hours. After cooling, use a mechanical mill to crush the mixture to D50 of 8 μm, and obtain hard carbon precursor A with disordered pore structure.

[0099] 3. Take 0.6 kg of phenolic resin, put it into 1 kg of ethanol, and stir for 2 hours, to dilute and disperse the phenolic resin thoroughly. Obtain a phenolic resin solution with a viscosity of 237 cP and a carbon residue content of 9%.

[0100] 4. Take 0.5 kg of hard carbon precursor A and 0.06 kg of the above resin solution, put them into a planetary dispersion mixer, stir at 120 rpm for 1 hour, and knead thoroughly, to obtain a composite.

[0101] 5、The composite is transferred to an electric heating mixer, and heated to 100°C at a rate of 4°C / min, and then heated to 400°C at a rate of 2°C / min, and after 2 hours of heat preservation, nitrogen is selected as the atmosphere for the whole process, to obtain hard carbon precursor B.

[0102] 6、The hard carbon precursor B is placed in a tube furnace for high-temperature heat treatment under a nitrogen atmosphere, heated to 600°C at a rate of 3°C / min, heat preserved for 1 hour, heated to 1300°C at a rate of 2°C / min, and heat preserved for 4 hours. After cooling to room temperature, the material is discharged to obtain the hard carbon negative electrode material.

[0103] Example 4

[0104] 1、Take 5kg of pitch, use a mechanical mill to crush to D50 of 10μm.

[0105] 2、Take 1kg of crushed pitch and 0.08kg of cyclopentadiene in a planetary dispersion mixer, stir at 120rpm for 1 hour, and fully knead. The material is discharged and placed in a resistance furnace, air is introduced, and the equipment is heated to 500°C, and heat preserved for 4 hours. After cooling and discharging, the material is crushed to D50 of 8μm using a mechanical mill, to obtain hard carbon precursor A containing disordered pore structure.

[0106] 3、Take 0.3kg of phenolic resin and place it in 1kg of ethanol, and continuously stir for 2 hours to fully dilute and disperse, to obtain a phenolic resin solution with a viscosity of 292cP and a carbon residue content of 15%.

[0107] 4、Take 0.5kg of hard carbon precursor A and 0.1kg of the above resin solution in a planetary dispersion mixer, continuously stir at 120rpm for 1 hour, and fully knead, to obtain a composite.

[0108] 5、The composite is transferred to an electric heating mixer, and heated to 80°C at a rate of 2°C / min, and then heated to 200°C at a rate of 1°C / min, and after 4 hours of heat preservation, nitrogen is selected as the atmosphere for the whole process, to obtain hard carbon precursor B.

[0109] 6、The hard carbon precursor B is placed in a tube furnace for high-temperature heat treatment under a nitrogen atmosphere, heated to 400°C at a rate of 3°C / min, heat preserved for 2 hours, heated to 1000°C at a rate of 2°C / min, and heat preserved for 6 hours. After cooling to room temperature, the material is discharged to obtain the hard carbon negative electrode material.

[0110] Comparative Example 1

[0111] 1、Take 5kg of pitch, use a mechanical mill to crush to D50 of 10μm.

[0112] 2、Take 1kg of crushed pitch and place it in a resistance furnace, introduce air, and heat the equipment to 500°C, and heat preserved for 4 hours. After cooling and discharging, the material is crushed to D50 of 8μm using a mechanical mill, to obtain a precursor.

[0113] 3. Take 0.3 kg of phenolic resin and put it into 1 kg of ethanol, stirring for 2 hours, to fully dilute and disperse, to obtain a phenolic resin solution with a viscosity of 292 cP and a carbon residue content of 15%.

[0114] 4. Take 0.5 kg of hard carbon precursor A and 0.1 kg of the above resin solution and put them into a planetary dispersion stirrer, stirring at 120 rpm for 1 hour, to fully knead, to obtain a composite.

[0115] 5. Transfer the composite to an electric heating mixer, and heat it to 150°C at a rate of 4°C / min, and then heat it to 300°C at a rate of 2°C / min, and after 2 hours of heat preservation, use nitrogen gas as the atmosphere for the whole process, to obtain hard carbon precursor B.

[0116] 6. Put hard carbon precursor B into a tube furnace for high-temperature heat treatment, under a nitrogen atmosphere, heat it to 600°C at a rate of 3°C / min, and heat it for 1 hour, heat it to 1300°C at a rate of 2°C / min, and heat it for 4 hours, and then wait for it to cool to room temperature, to obtain hard carbon negative electrode material.

[0117] Comparative Example 2

[0118] 1. Take 5 kg of pitch and use a mechanical grinder to crush it to a D50 of 10 μm.

[0119] 2. Take 1 kg of the crushed pitch and 0.08 kg of cyclopentadiene and put them into a planetary dispersion stirrer, stirring at 120 rpm for 1 hour, to fully knead. After discharging, put the material into an electric resistance furnace, and pass in air, and heat the equipment to 500°C, and heat it for 4 hours. After cooling and discharging, use a mechanical grinder to crush it to a D50 of 8 μm, to obtain hard carbon precursor A with a disordered pore structure.

[0120] 3. Take 0.5 kg of hard carbon precursor A and 0.1 kg of phenolic resin and put them into a planetary dispersion stirrer, stirring at 120 rpm for 1 hour, to fully knead, to obtain a composite.

[0121] 4. Transfer the composite to an electric heating mixer, and heat it to 150°C at a rate of 4°C / min, and then heat it to 300°C at a rate of 2°C / min, and after 2 hours of heat preservation, use nitrogen gas as the atmosphere for the whole process, to obtain hard carbon precursor B.

[0122] 5. Put hard carbon precursor B into a tube furnace for high-temperature heat treatment, under a nitrogen atmosphere, heat it to 600°C at a rate of 3°C / min, and heat it for 1 hour, heat it to 1300°C at a rate of 2°C / min, and heat it for 4 hours, and then wait for it to cool to room temperature, to obtain stable hard carbon negative electrode material.

[0123] Effect Example 1

[0124] (1) Preparation of the electrode

[0125] The hard carbon negative electrode material obtained from Example 1-4 and Comparative Example 1-2 was mixed with acetylene black conductive agent and PVDF binder in a mass ratio of 8:1:1 at room temperature, and NMP was used as the solvent to configure a uniform slurry. The slurry was uniformly coated on a copper foil with a coating density of about 6 mg / cm 2 Then the copper foil was placed in a vacuum drying oven and baked at 80°C for 12 h. The baked copper foil was cut into a circular piece with an area of 2 cm 2 to make a working electrode.

[0126] (2) Assembly of the button cell

[0127] Assembly of the sodium-ion button cell: In a vacuum glove box, the product obtained in step (1) was used as the working electrode, GE-Whatman glass fiber separator was used as the separator, and 1 mol / L NaPF6 / EC:DMC (volume ratio of 1:1) solution was used as the electrolyte. The sodium-ion button cell was assembled in a CR-2032 type button cell with a metal sodium sheet as the negative electrode and the counter electrode, and was tightly mechanically sealed.

[0128] (3) Test of the specific capacity and capacity retention rate of the sodium-ion button cell

[0129] After the assembled battery was placed at room temperature for 24 h, electrochemical test was started. On an Arbin battery test system, according to the mass of the active material, a current of 100 mA / g was used in the first week, and the first discharge was to 0 V, and the charging voltage interval was 0 V-2 V. After the charging or discharging was completed, the next step was carried out after 5 min. After 1000 cycles, the capacity retention rate was tested by 1C constant current charging and discharging cycles.

[0130] Test results of the (002) interlayer spacing, tap density, BET, and the first charge capacity, the first coulombic efficiency, and the capacity retention rate after 1000 cycles of the hard carbon negative electrode material obtained from Example 1-4 and Comparative Example 1-2 when used in a sodium-ion battery are shown in Table 1.

[0131] Table 1: Test results of the performance of the hard carbon negative electrode material

[0132]

[0133] As shown in Figure 1 , the hard carbon negative electrode material obtained from Example 1 has pore structure distribution in the range of 0.5-0.6 nm and 0.8-0.9 nm, which is beneficial to the storage of sodium ions. From Figure 2It can be seen that the hard carbon negative material obtained in Example 1 shows a wide peak, which is a typical hard carbon structure. From the test results in Table 1 above, it can be seen that the hard carbon negative material prepared by the preparation method of the application has a larger (002) crystal face interlayer spacing, a smaller specific surface area, a higher tap density, a higher first charge-discharge efficiency, and a high capacity retention rate after 1000 cycles. The performance of the hard carbon negative material in Examples 1-4 is better than that in Comparative Examples 1-2, and it can be seen that the hard carbon negative material prepared without adjusting or modifying the pore structure has a large specific surface area, a low first charge-discharge efficiency, and a low capacity retention rate.

Claims

1. A method for producing a hard carbon negative electrode material, characterized by, It comprises the following steps: S1. mixing carbon source material powder with foaming agent for primary foaming to obtain hard carbon precursor A; S2. mixing the hard carbon precursor A with resin solution for secondary foaming to obtain hard carbon precursor B; the viscosity of the resin solution is 50-500 cP, the residual carbon content of the resin solution is 1-40%; the residual carbon content refers to the carbon content of the remaining organic matter after heat treatment, accounting for the mass percentage of total organic matter; S3. heat treatment of the hard carbon precursor B to obtain hard carbon negative electrode material; The mass ratio of the carbon source material powder to the foaming agent is 100: (0.1-30); The foaming agent is one or a combination of at least two of sec-butyl acetate, adiponitrile, polyisobutylene, linalool, methyl pinacolate, piperylene, cyclopentadiene, and isoprene; In step S1, the temperature of the primary foaming is 500-600℃; In step S2, the mass ratio of the hard carbon precursor A to the resin solution is 100: (0.1-40); The temperature of the secondary foaming is 50-400℃.

2. The method of producing a hard carbon negative electrode material according to claim 1, characterized by, In step S1, the carbon source material powder is obtained by pre-treatment of carbon source material.

3. The method of producing a hard carbon negative electrode material according to claim 1, characterized by, The D50 of the carbon source material powder is 1-40 μm.

4. The method of producing a hard carbon negative electrode material according to claim 2, characterized by, The carbon source material includes one or a combination of at least two of pitch, glucose, sucrose, starch, and cellulose.

5. The method of producing a hard carbon negative electrode material according to claim 2, characterized by, In step S1, the pre-treatment is crushing or pulverizing.

6. The method of producing a hard carbon negative material according to claim 2, wherein In step S1, the pre-treatment device includes airflow mill, mechanical mill, roller mill, or ball mill.

7. The preparation method of the hard carbon negative electrode material according to claim 2, wherein, The D50 of the carbon source material powder is 10 μm.

8. The method of producing a hard carbon negative material according to claim 1, wherein The mass ratio of the carbon source material powder to the foaming agent is 100:8 or 100:

15.

9. The method of producing a hard carbon negative material according to claim 1, wherein The time of the primary foaming is 0.5-6 h.

10. The method of producing a hard carbon negative material according to claim 1, wherein The atmosphere of the primary foaming is one or more of air, ammonia, oxygen, and ozone.

11. The method of producing a hard carbon negative material according to claim 1, wherein The device of the primary foaming is muffle furnace, resistance furnace, tube furnace, or roller furnace.

12. The method of producing a hard carbon negative material according to claim 1, wherein The primary foaming further comprises dispersion kneading.

13. The method of producing a hard carbon negative material according to claim 1, wherein The primary foaming further comprises pulverizing.

14. The method of producing a hard carbon negative electrode material according to claim 12, characterized by, The device of the dispersion kneading is kneader, planetary dispersion stirrer, VC mixer, double-pot mixer, or vertical mixer.

15. The method of producing a hard carbon negative electrode material according to claim 12, characterized by The time of the dispersion kneading is 0.5-2 h.

16. The method of producing a hard carbon negative electrode material according to claim 14, characterized by, The speed of the dispersion kneading is 100-150 rpm.

17. The method of producing a hard carbon negative material according to claim 15, wherein The time of the dispersion kneading is 1 h.

18. The method of producing a hard carbon negative material according to claim 16, wherein The speed of the dispersion kneading is 120 rpm.

19. The method of producing a hard carbon negative material according to claim 1, wherein In step S1, the temperature of the primary foaming is 500℃ or 600℃.

20. The method of producing a hard carbon negative material according to claim 1, wherein The time of the primary foaming is 4 h.

21. The method of producing a hard carbon negative material according to claim 1, wherein In step S2, the preparation method of the resin solution is adding resin into solvent for dilution and dispersion.

22. The method of producing a hard carbon negative electrode material according to claim 21, wherein The mass ratio of the solvent to the resin is 100: (1-60).

23. The method of producing a hard carbon negative material according to claim 21, wherein The solvent includes one or a combination of at least two of acetone, diethyl ether, ethanol, styrene, fatty acid ester, methacrylic ester, tetrahydrofuran, and deionized water.

24. The method of producing a hard carbon negative material according to claim 21, wherein The resin includes thermosetting resin and / or thermoplastic resin.

25. The method of producing a hard carbon negative material according to claim 21, wherein The time of the dilution and dispersion is 0.5-4 h.

26. The method of producing a hard carbon negative material according to claim 22, wherein The mass ratio of the solvent to the resin is 100:30 or 100:

60.

27. The method of producing a hard carbon negative material according to claim 24, wherein The resin is phenolic resin.

28. The method of producing a hard carbon negative material according to claim 25, wherein The dilution and dispersion time is 2 h.

29. The method of claim 1, wherein the hard carbon negative material is prepared by, The secondary foaming step comprises mixing and dispersing the hard carbon precursor A with a resin solution, followed by foaming and coating, and then crushing to obtain the hard carbon precursor B.

30. The method of producing a hard carbon negative material according to claim 1, wherein The viscosity of the resin solution is 237-292 cP.

31. The method of producing a hard carbon negative material according to claim 1, wherein The carbon residue content of the resin solution is 9-15%.

32. The method of producing a hard carbon negative material according to claim 1, wherein In step S2, the mass ratio of the hard carbon precursor A to the resin solution is 100:12, 100:20, or 100:

30.

33. The method of producing a hard carbon negative material according to claim 1, wherein In step S2, the secondary foaming device is a screw belt mixer, an electric heating mixer, or a horizontal kettle.

34. The method of producing a hard carbon negative material according to claim 1, wherein The secondary foaming temperature control mode is constant temperature, temperature rise, or temperature rise-constant temperature interval.

35. The method of producing a hard carbon negative material according to claim 1, wherein The secondary foaming adopts a segmented temperature control mode, which includes a first temperature control and a second temperature control in sequence; the temperature of the second temperature control is higher than that of the first temperature control.

36. The method of producing a hard carbon negative material according to claim 1, wherein The secondary foaming atmosphere includes an inert atmosphere and / or an oxidative atmosphere.

37. The method of producing a hard carbon negative material according to claim 1, wherein The inert atmosphere is argon or nitrogen.

38. The method of producing a hard carbon negative material according to claim 37, wherein The oxidative atmosphere is air, oxygen, or ozone.

39. The method of producing a hard carbon negative material according to claim 37, wherein The D50 of the hard carbon precursor B is 1-20 μm.

40. The method of producing a hard carbon negative material according to claim 1, wherein The secondary foaming holding time is 2 h.

41. The method of producing a hard carbon negative material according to claim 34, wherein When the temperature rise mode is adopted, the temperature rise rate is 1-10 ℃ / min.

42. The method of producing a hard carbon anode material of claim 35, wherein, The end point temperature of the first temperature control is 100-150 ℃.

43. The method of producing a hard carbon negative material according to claim 36, wherein The temperature rise rate of the first temperature control is 2-4 ℃ / min.

44. The method of producing a hard carbon anode material of claim 36, wherein, The end point temperature of the second temperature control is 300-400 ℃.

45. The method of producing a hard carbon anode material of claim 36, wherein, The temperature rise rate of the second temperature control is 2-4 ℃ / min.

46. The method of producing a hard carbon anode material according to claim 36, wherein The D50 of the hard carbon precursor B is 8 μm.

47. The method of producing a hard carbon anode material of claim 40, wherein, The end point temperature of the first temperature control is 100 ℃ or 150 ℃.

48. The method of producing a hard carbon anode material according to claim 43, wherein The temperature rise rate of the first temperature control is 2 ℃ / min or 4 ℃ / min.

49. The method of producing a hard carbon anode material according to claim 44, wherein The end point temperature of the second temperature control is 300 ℃ or 400 ℃.

50. The method of producing a hard carbon anode material of claim 45, wherein, The temperature rise rate of the second temperature control is 2 ℃ / min or 4 ℃ / min.

51. The method of producing a hard carbon anode material of claim 46, wherein, In step S3, the heat treatment is programmed automatic temperature rise.

52. The method of producing a hard carbon anode material according to claim 1, wherein In step S3, the heat treatment temperature is 900-1400 ℃.

53. The method of producing a hard carbon anode material according to claim 1, wherein In step S3, the heat treatment holding time is 0.5-8 h.

54. The method of producing a hard carbon anode material according to claim 1, wherein In step S3, the heat treatment adopts a segmented temperature control mode, which includes a first temperature control and a second temperature control in sequence; the temperature of the second temperature control is higher than that of the first temperature control.

55. The method of producing a hard carbon anode material according to claim 1, wherein In step S3, the heat treatment is performed in a reducing atmosphere and / or an inert atmosphere.

56. The method of producing a hard carbon anode material of claim 1, wherein, In step S3, the heat treatment device is a programmed automatic temperature rise-holding device.

57. The method of producing a hard carbon anode material according to claim 1, wherein The heat treatment holding time is 5 h or 6 h.

58. The method of producing a hard carbon anode material of claim 54, wherein, The end point temperature of the first temperature control is 400-600 ℃.

59. The method of producing a hard carbon anode material of claim 55, wherein, The temperature rise rate of the first temperature control is 2-4 ℃ / min.

60. The method of producing a hard carbon anode material of claim 55, wherein, The holding time of the first temperature control is 1-2 h.

61. The method of producing a hard carbon anode material of claim 55, wherein, The end point temperature of the second temperature control is 1000-1300 ℃.

62. The method of producing a hard carbon anode material of claim 55, wherein, The temperature rise rate of the second temperature control is 1-3 ℃ / min.

63. The method of producing a hard carbon anode material of claim 55, wherein, The holding time of the second temperature control is 3-5 h.

64. The method of producing a hard carbon anode material of claim 55, wherein, The reducing atmosphere is a combination of one or more of ammonia, hydrogen, and argon.

65. The method of producing a hard carbon anode material of claim 56, wherein, The inert atmosphere is argon and / or nitrogen.

66. The method of producing a hard carbon anode material of claim 56, wherein, ​ 67. The method of producing a hard carbon anode material of claim 57, wherein, The equipment for the heat treatment is a box furnace, a tube furnace, a roller hearth furnace, a pusher furnace, a tunnel furnace or a vacuum furnace.

68. The method of producing a hard carbon anode material of claim 59, wherein, The terminal temperature of the first temperature control is 400℃ or 600℃.

69. The method of producing a hard carbon anode material of claim 60, wherein, The heating rate of the first temperature control is 3℃ / min.

70. The method of producing a hard carbon anode material of claim 61, wherein, The holding time of the first temperature control is 1h or 2h.

71. The method of producing a hard carbon anode material of claim 62, wherein, The terminal temperature of the second temperature control is 1000℃ or 1300℃.

72. The method of producing a hard carbon anode material of claim 63, wherein, The heating rate of the second temperature control is 2℃ / min.

73. The method of producing a hard carbon anode material of claim 64, wherein, The holding time of the second temperature control is 4h. 74.A hard carbon anode material prepared by the method of any one of claims 1-73.

75. The hard carbon anode material of claim 74, wherein, The (002) interlayer spacing of the hard carbon anode material is 0.379-0.395nm.

76. The hard carbon anode material of claim 74, wherein, The (002) interlayer spacing of the hard carbon anode material is 0.395 nm, 0.391 nm, 0.394 nm or 0.390 nm.

77. The hard carbon anode material of claim 74, wherein, The pore size distribution curve of the hard carbon anode material has characteristic peaks in the pore size ranges of 0.5-0.6nm and 0.8-0.9nm. 78.The use of the hard carbon anode material of claim 74 in a battery.

79. Use of the hard carbon anode material of claim 78 in a battery, wherein The battery is a lithium ion or sodium ion battery. 80.A battery comprising the hard carbon anode material of claim 74.

81. The battery of claim 80, wherein the electrolyte comprises a lithium salt. The battery is a lithium ion or sodium ion battery.

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