Modified additives, electrode paste based on modified additives, and method for preparing the same

Abstract

The application discloses a modified additive, an electrode paste based on the modified additive and a preparation method thereof, and belongs to the technical field of electrode paste preparation. The modified asphalt which is modified by natural latex and nano-silicon dioxide is taken as a core, a carboxylated nano-cellulose connecting layer is constructed on the surface of the core through emulsification technology, and then a graphene oxide shell layer is constructed outside the connecting layer, so that the modified additive with a core-shell structure is formed after drying; the modified additive disclosed by the application can constrain the core asphalt during the sintering stage of the electrode paste, avoids the premature flow of the core asphalt, stabilizes the paste column form to inhibit delamination; the carboxylated nano-cellulose is carbonized into short-range carbon fibers and the graphene oxide is reduced into reduced graphene oxide at high temperature, and the two are interwoven with the coking product of the modified asphalt to form a composite reinforcing network, so that the mechanical strength and toughness of the electrode are improved; the modified additive disclosed by the application is added into aggregates, powders and binders in the dry mixing stage, and the electrode paste based on the modified additive is prepared, and the electrode paste has good hard breaking resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrode paste preparation, in particular to a modified additive, an electrode paste based on the modified additive and a preparation method thereof. BACKGROUND

[0002] As the core conductive consumables of high-temperature metallurgical equipment such as calcium carbide furnace and iron alloy furnace, electrode paste is mainly made of carbon aggregate such as anthracite, metallurgical coke and graphite scrap mixed with coal tar pitch binder, and then is prepared by high-temperature baking. It has the key performances of electrical conductivity, high-temperature resistance and thermal shock resistance. The quality of electrode paste directly determines the smelting efficiency, electrode consumption rate and production safety of the electric furnace. Hard breakage of electrode refers to the fracture of sintered electrode below the conductive clamp. Once it occurs, it will directly lead to smelting stoppage, causing significant production loss and safety risk. Low softening point of electrode paste will cause hard breakage of electrode, because the electrode paste with low softening point will have a high liquid column during sintering, causing the separation of solid material and binder, and thus resulting in hard breakage. Therefore, developing a modified additive capable of improving the hard breakage resistance of electrode paste and preparing an electrode paste based on the modified additive become a new strategy to alleviate the hard breakage problem of electrode paste. SUMMARY

[0003] The purpose of the present application is to provide a modified additive. The modified additive has a core-shell structure, in which the core is modified pitch compounded with natural latex and nano-silicon dioxide, a carboxylated nanocellulose connection layer is constructed on the surface of the core by emulsification technology, and then a graphene oxide shell layer is constructed outside the connection layer. During the sintering process of electrode paste, the outer graphene oxide shell layer and the intermediate carboxylated nanocellulose connection layer jointly constrain the premature flow of the core pitch, stabilize the paste column morphology in the early stage of sintering, and alleviate the separation of aggregate and binder. Under high-temperature baking, the carboxylated nanocellulose is carbonized to form short-range carbon fibers, and the graphene oxide is reduced to reduced graphene oxide. The two interweave with the coke after coking of the modified pitch to form a composite coking structure, which can improve the mechanical strength and toughness of the electrode, and can alleviate the hard breakage problem of the electrode paste based on the modified additive caused by sintering separation and insufficient bulk strength.

[0004] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0005] In a first aspect, the present application provides a modified additive, which has a core-shell structure. The core is modified pitch compounded with natural latex and nano-silicon dioxide. A carboxylated nanocellulose connection layer is coated on the surface of the modified pitch by emulsification, and a graphene oxide shell layer is constructed outside the connection layer by hydrogen bonding adsorption. The modified pitch is pitch containing natural latex and nano-silicon dioxide.

[0006] Further, the carboxylated nanocellulose is any one of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidized nanocellulose or carboxymethylated nanocellulose; in the modified asphalt, the mass ratio of natural latex, nanosilica and asphalt is 6: (2-4): 100; the mass ratio of the modified asphalt, carboxylated nanocellulose and graphene oxide is 10: (0.9-1.35): (1-1.8).

[0007] In a second aspect, the present application provides a preparation method of a modified additive, comprising the following steps:

[0008] Step A1, adding natural latex to asphalt, stirring, adding nanosilica, mixing to obtain modified asphalt;

[0009] Step A2, dispersing carboxylated nanocellulose in water, adding sodium dodecyl sulfonate to obtain an aqueous phase; adding the modified asphalt into the aqueous phase, emulsifying to obtain a modified asphalt emulsion;

[0010] Step A3, dispersing graphene oxide in deionized water to obtain a graphene oxide dispersion; adding the graphene oxide dispersion into the modified asphalt emulsion, stirring, centrifuging, washing the precipitate with deionized water, vacuum drying to obtain a modified additive.

[0011] Further, in the step A1, the temperature of the stirring is 160-170℃, the stirring speed is 2500-3500rpm, and the stirring time is 25-45min; the temperature of the mixing is 170-180℃, the mixing speed is 3500-4500rpm, and the mixing time is 40-60min.

[0012] Further, in the step A2, the mass ratio of the carboxylated nanocellulose, sodium dodecyl sulfonate and water is (1-1.5): 0.1: (98.5-99); the temperature of the emulsifying is 50-60℃, the rotation speed of the emulsifying is 17000-18000rpm, and the emulsifying time is 2-5min.

[0013] Further, in the step A3, the mass ratio of the graphene oxide and deionized water is (1-1.8): (48.2-49); the stirring speed is 400-600rpm, and the stirring time is 18-24h; the temperature of the vacuum drying is 20-30℃, the vacuum drying time is 12-18h, and the vacuum degree of the vacuum drying is less than 10kPa.

[0014] In a third aspect, the present application provides a modified additive-based electrode paste, which comprises aggregate, powder, binder and modified additive; the mass ratio of the aggregate, powder, binder and modified additive is (55-65):(15-17):(15-25):(3-5).

[0015] In a fourth aspect, the present application provides a preparation method of the modified additive-based electrode paste, which comprises the following steps:

[0016] Step S1, mixing the aggregate and powder after calcination and crushing, adding the modified additive, and dry mixing to obtain mixed dry materials;

[0017] Step S2, preheating the mixing kettle, adding the mixed dry materials, adding the molten binder, and mixing to obtain an electrode paste blank;

[0018] Step S3, pressing and forming the electrode paste blank, and aging to obtain the modified additive-based electrode paste.

[0019] Further, in the step S1, the aggregate comprises any one or more of anthracite, residual pole, graphite scrap and calcined petroleum coke; the powder comprises any one or more of graphite powder and coke powder; the mixing speed is 100-150 rpm, the mixing time is 10-15 min, and the mixing temperature is 20-30℃; the dry mixing speed is 120-200 rpm, the mixing time is 15-20 min, and the mixing temperature is 20-30℃.

[0020] Further, in the step S2, the preheating temperature of the mixing kettle is 80-100℃; the binder is medium-temperature coal tar pitch or high-temperature coal tar pitch; the temperature of the molten binder is 100-120℃; the mixing speed is 50-80 rpm, the mixing time is 30-45 min, and the mixing temperature is 110-130℃.

[0021] Further, in the step S3, the pressure for pressing and forming is 20-30 MPa, and the temperature is 100-120℃; the aging temperature is 25-35℃, and the aging time is 24-48 h.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The application provides a modified additive capable of improving the hard breaking resistance of electrode paste; the modified additive is added in the dry mixing stage of electrode paste production to prepare electrode paste based on the modified additive, and the electrode paste has good hard breaking resistance. The modified additive has a core-shell structure, and the core is bitumen modified by natural latex and nano-silicon dioxide. The softening point and high-temperature stability of the bitumen are improved, which can slow down the excessive flow of the electrode paste during baking, avoid the separation of solid materials and binders caused by the excessive height of the liquid paste column, and reduce the risk of hard breaking of the electrode paste. The modified bitumen emulsion is prepared by emulsification technology, and the carboxylated nanocellulose is used as an emulsifier, which can uniformly coat the surface of the modified bitumen droplets to form a connecting layer. The nanoscale fiber structure and the spatial distribution characteristics of the carboxyl group of the carboxylated nanocellulose can stabilize the bitumen emulsion and inhibit the separation of solid materials and binders, and can also combine with graphene oxide through hydrogen bonding. The outer graphene oxide is adsorbed on the connecting layer through hydrogen bonding to form a shell structure. During the sintering process of the electrode paste, the coating layer composed of the graphene oxide shell and the cellulose connecting layer can effectively slow down the premature flow of the internal modified bitumen after reaching the softening point, stabilize the paste column shape in the early sintering stage, thereby reducing the separation tendency of solid aggregates and liquid binders and reducing the occurrence of hard breaking. Secondly, during the high-temperature baking stage, the carboxylated nanocellulose and graphene oxide can be carbonized and interwoven with the coke after the modification of the bitumen, thereby constructing a composite coke network reinforced by reduced graphene oxide layers and short-range carbon fibers in the electrode body, which can improve the mechanical strength and toughness of the sintered electrode body. In addition, the two-dimensional sheet structure of graphene oxide helps to uniformly distribute heat in the paste, promoting a more uniform sintering process. The modified additive provided by the application can meet the requirements of the hard breaking resistance of the electrode paste during the baking and use stages, and can alleviate the electrode hard breaking problem caused by the separation of the electrode paste during sintering and the insufficient strength of the electrode body. Therefore, the electrode paste prepared by the application has good hard breaking resistance. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a flow chart for the preparation method of the modified additive. DETAILED DESCRIPTION

[0025] The technical scheme of the application will be described in detail below through specific embodiments. It should be understood that the embodiments of the application and the specific features in the embodiments are detailed descriptions of the technical scheme of the application, and are not limitations of the technical scheme of the application. In the case of no conflict, the technical features in the embodiments of the application and the embodiments can be combined with each other.

[0026] The term "and / or", only describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / ", generally represents that the front and rear associated objects have an "or" relationship.

[0027] Example 1

[0028] As shown in Figure 1 , a modified additive, the preparation method comprising:

[0029] Step A1, adding natural latex to asphalt, stirring at 3000 rpm for 35 min at 165 ℃, then adding nano-silicon dioxide, mixing at 4000 rpm for 50 min at 175 ℃, to obtain modified asphalt; wherein the mass ratio of natural latex, nano-silicon dioxide and asphalt is 6:3:100;

[0030] Step A2, dispersing TEMPO-oxidized nanocellulose in water, adding sodium dodecyl sulfonate to obtain an aqueous phase; wherein the mass ratio of TEMPO-oxidized nanocellulose, sodium dodecyl sulfonate and water is 1.25:0.1:98.75. Adding the modified asphalt into the aqueous phase, emulsifying at 17500 rpm for 4 min at 55 ℃ to obtain a modified asphalt emulsion;

[0031] Step A3, dispersing graphene oxide in deionized water, the mass ratio of graphene oxide to deionized water is 1.4:48.6, to obtain a graphene oxide dispersion; adding the graphene oxide dispersion into the modified asphalt emulsion, stirring at 500 rpm for 22 h, centrifuging, washing the precipitate with deionized water, and vacuum drying at 25 ℃ for 15 h, the vacuum degree of vacuum drying is less than 10 kPa, to obtain a modified additive, in the modified additive, the mass ratio of modified asphalt, TEMPO-oxidized nanocellulose and graphene oxide is 10:1.125:1.4.

[0032] Example 2

[0033] As shown in Figure 1 , a modified additive, the preparation method comprising:

[0034] Step A1, adding natural latex to asphalt, stirring at 2500 rpm for 45 min at 160 ℃, then adding nano-silicon dioxide, mixing at 3500 rpm for 60 min at 170 ℃, to obtain modified asphalt; wherein the mass ratio of natural latex, nano-silicon dioxide and asphalt is 6:2:100;

[0035] Step A2, dispersing carboxymethylated nanocellulose in water, adding sodium dodecyl sulfonate to obtain an aqueous phase; wherein the mass ratio of carboxymethylated nanocellulose, sodium dodecyl sulfonate and water is 1:0.1:99. Adding the modified asphalt into the aqueous phase, emulsifying at 18000 rpm for 2 min at 50 ℃ to obtain a modified asphalt emulsion;

[0036] Step A3, disperse graphene oxide in deionized water, the mass ratio of graphene oxide to deionized water is 1:49, to obtain a graphene oxide dispersion; add the graphene oxide dispersion to the modified asphalt emulsion, stir at a speed of 400 rpm for 24 h, centrifuge, wash the precipitate with deionized water, and vacuum dry at 20℃ for 18 h, the vacuum degree of vacuum drying is less than 10 kPa, to obtain a modified additive, in the modified additive, the mass ratio of modified asphalt, carboxymethylated nanocellulose and graphene oxide is 10:0.9:1.

[0037] Example 3

[0038] As shown in Figure 1 , a modified additive, the preparation method thereof comprises:

[0039] Step A1, add natural latex to asphalt, stir at a speed of 3500 rpm at 170℃ for 25 min, then add nanosilica, mix at a speed of 4500 rpm at 180℃ for 40 min, to obtain modified asphalt; wherein the mass ratio of natural latex, nanosilica and asphalt is 6:4:100;

[0040] Step A2, disperse carboxymethylated nanocellulose in water, add sodium dodecyl sulfonate, to obtain an aqueous phase; wherein the mass ratio of carboxymethylated nanocellulose, sodium dodecyl sulfonate and water is 1.5:0.1:98.5. Add the modified asphalt to the aqueous phase, emulsify at a speed of 17000 rpm at 55℃ for 5 min, to obtain a modified asphalt emulsion;

[0041] Step A3, disperse graphene oxide in deionized water, the mass ratio of graphene oxide to deionized water is 1.8:48.2, to obtain a graphene oxide dispersion; add the graphene oxide dispersion to the modified asphalt emulsion, stir at a speed of 600 rpm for 18 h, centrifuge, wash the precipitate with deionized water, and vacuum dry at 35℃ for 12 h, the vacuum degree of vacuum drying is less than 10 kPa, to obtain a modified additive, in the modified additive, the mass ratio of modified asphalt, carboxymethylated nanocellulose and graphene oxide is 10:1.35:1.8.

[0042] Example 4

[0043] A modified additive-based electrode paste, the preparation method thereof is as follows:

[0044] Step S1, mix the calcined and crushed aggregates and the powder at 25℃ with a rotation speed of 130 rpm for 12 min, add the modified additive prepared in Example 1, and dry mix at 25℃ with a rotation speed of 160 rpm for 18 min to obtain mixed dry materials; wherein the aggregates are anthracite, residual pole, graphite scrap and calcined petroleum coke, and the mass ratio of anthracite, residual pole, graphite scrap and calcined petroleum coke is 40:40:10:10; the powder is graphite powder and coke powder, and the mass ratio of graphite powder and coke powder is 60:40;

[0045] Step S2, preheat the mixing kettle to 90℃, add the mixed dry materials, and add molten medium temperature coal pitch at 110℃; mix at 120℃ with a rotation speed of 65 rpm for 37 min to obtain an electrode paste blank;

[0046] Step S3, press the electrode paste blank at a pressure of 25 MPa and a temperature of 110℃, and then naturally cool to room temperature; then age at 30℃ for 36 h to obtain a modified additive-based electrode paste.

[0047] In the modified additive-based electrode paste prepared according to the above method, the mass ratio of aggregates, powder, binder and modified additive is 60:16:20:4.

[0048] Example 5

[0049] A modified additive-based electrode paste is prepared by the following method:

[0050] Step S1, mix the calcined and crushed aggregates and the powder at 30℃ with a rotation speed of 150 rpm for 10 min, add the modified additive prepared in Example 2, and dry mix at 30℃ with a rotation speed of 200 rpm for 15 min to obtain mixed dry materials; wherein the aggregates are anthracite, residual pole and calcined petroleum coke, and the mass ratio of anthracite, residual pole and calcined petroleum coke is 35:45:20; the powder is graphite powder;

[0051] Step S2, preheat the mixing kettle to 100℃, add the mixed dry materials, and add molten high temperature coal pitch at 120℃; mix at 130℃ with a rotation speed of 80 rpm for 30 min to obtain an electrode paste blank;

[0052] Step S3, press the electrode paste blank at a pressure of 20 MPa and a temperature of 120℃, and then naturally cool to room temperature; then age at 35℃ for 24 h to obtain a modified additive-based electrode paste.

[0053] In the modified additive-based electrode paste prepared according to the above method, the mass ratio of aggregates, powder, binder and modified additive is 65:17:15:3.

[0054] Example 6

[0055] A modified additive-based electrode paste is prepared by the following method:

[0056] Step S1, the calcined and crushed aggregate and the powder are mixed at 20℃ for 15min at a speed of 100rpm, the modified additive prepared in Example 3 is added, and dry mixing is performed at 20℃ for 20min at a speed of 120rpm to obtain mixed dry materials; wherein the aggregate is anthracite and calcined petroleum coke, and the mass ratio of anthracite to calcined petroleum coke is 55:45; the powder is coke powder;

[0057] Step S2, the mixing kettle is preheated to 80℃, the mixed dry materials are added, and 100℃ molten medium temperature coal pitch is added; mixing is performed at 110℃ for 45min at a speed of 50rpm to obtain an electrode paste blank;

[0058] Step S3, the electrode paste blank is pressed and formed at a pressure of 30MPa and a temperature of 100℃, and after natural cooling to room temperature, it is aged at 25℃ for 48h to obtain a modified additive-based electrode paste.

[0059] In the modified additive-based electrode paste prepared by the above method, the mass ratio of the aggregate, the powder, the binder and the modified additive is 55:15:25:5.

[0060] Comparative Example 1

[0061] An electrode paste is different from Example 4 in that the modified additive prepared in Example 1 is not added, and the other operation steps and process parameters are exactly the same as those of Example 4.

[0062] Comparative Example 2

[0063] An electrode paste is different from Example 4 in that the added modified additive omits step A3, and the modified asphalt emulsion is directly spray dried to prepare the modified additive, and the rest is exactly the same as Example 1; the preparation process and process parameters of the modified additive-based electrode paste are exactly the same as those of Example 4.

[0064] Comparative Example 3

[0065] An electrode paste is different from Example 4 in that the added modified additive omits step A2, and the modified asphalt is directly mixed with the graphene oxide dispersion, and the rest is exactly the same as Example 1; the preparation process and process parameters of the modified additive-based electrode paste are exactly the same as those of Example 4.

[0066] Comparative Example 4

[0067] An electrode paste, which is different from example 4 in that the added modified additive omits the modification process in step A1, the core of the core-shell structure is the original asphalt without modification, the rest is exactly the same as example 1; the preparation process and process parameters of the electrode paste based on the modified additive are exactly the same as example 4.

[0068] Comparative example 5

[0069] An electrode paste, which is different from example 4 in that the added modified additive is modified asphalt, carboxylated nanocellulose dispersion and graphene oxide dispersion, and the three are not combined into the core-shell structure in example 1; the preparation process and process parameters of the electrode paste based on the modified additive are exactly the same as example 4.

[0070] Electrode paste performance test:

[0071] The electrode paste prepared in example 4 to example 6 and comparative example 1 to comparative example 5 was tested for performance. The electrode paste was treated as follows before testing to simulate the roasting process during production using the electrode paste.

[0072] Step B1, take 6 kg of sample, without destroying the particle size composition, crush all to below 25 mm, divide into two parts by quartering method. One part is reserved as a sample, the other part is heated to a temperature not exceeding 150℃, and carefully stirred while heating until the paste is completely melted, then packed into an iron cylinder by pounding in three times. The iron cylinder is vertically placed on the iron cylinder stand, cooled to room temperature, and packed into the roasting crucible.

[0073] Step B2, lay a layer of 50 mm thick filler at the bottom of the crucible, place the electrode paste packed iron cylinder into the crucible, the distance between the iron cylinder and the crucible wall is 20 mm, and the distance between the cylinders is 15 mm. The temperature measuring thermocouple is placed in the middle of the crucible, and its hot end is parallel to the bottom of the sample. After filling all the gaps in the crucible with the filler, the crucible is placed in the constant temperature zone of the roasting furnace for roasting.

[0074] Step B3, power heating, the heating rate is 100℃ / h, after gradually increasing the temperature, the sample in the iron cylinder melts, and when the temperature reaches 900℃, the heating is stopped after keeping the temperature for 3h, and the furnace is naturally cooled to below 100℃, and the crucible is removed.

[0075] Step B4, take out the sample from the iron cylinder, remove the filler adhered to the bottom, cut off the bottom 10mm, then process into a cylindrical sample with diameter x length of 45mm x 40mm for testing the resistivity of the electrode paste and the compressive strength of the electrode paste. The resistivity of the electrode paste and the compressive strength of the electrode paste are tested according to the standard YB / T4448-2014, and the test results are shown in table 1.

[0076] Table 1 Test results of electrode paste performance of Example 4-Example 6 and Comparative Example 1-Comparative Example 5

[0077] Electrode paste resistivity (µΩ m) Electrode paste compressive strength (MPa) Example 4 27.6 48.5 Example 5 30.8 46.2 Example 6 29.5 45.3 Comparative Example 1 65.3 21.5 Comparative Example 2 89.3 30.7 Comparative Example 3 73.6 25.1 Comparative Example 4 43.6 29.3 Comparative Example 5 59.8 22.4

[0078] As can be seen from the data in Table 1, the resistivity of the electrode paste prepared in Example 4-Example 6 is greatly reduced, and the compressive strength of the electrode paste is greatly improved, which is more than doubled compared with that of Comparative Example 1.

[0079] Comparative Example 1 does not add a modified additive, and the resistivity and compressive strength of the electrode paste are within the national standard range, which is a qualified conventional product. The modified additive added in Comparative Example 2 lacks an oxidized graphene shell layer, and the modified asphalt itself can slightly improve the conductivity, but there is no continuous conductive network constructed by oxidized graphene, and the lack of shell constraints causes the paste column to flow slightly, the structure to be uneven, and the conductive path to break during baking, so that the final resistivity is higher than that of Comparative Example 1, which is the highest among all test samples; the compressive strength of the electrode paste prepared in Comparative Example 2 is higher than that of Comparative Example 1, but it is still lower than that of Example 4-Example 6 and Comparative Example 4, which may be because the modified additive in Comparative Example 2 is carbonized at high temperature to form short-range carbon fibers, which are compounded with the modified asphalt, thereby still being able to enhance the mechanical strength of the electrode paste, which is manifested as the improvement of the compressive strength of the electrode paste. The modified additive added in Comparative Example 3 lacks a connecting layer of carboxylated nanocellulose, and the resistivity of the electrode paste is relatively high, only next to that of Comparative Example 2; at the same time, the compressive strength of the electrode paste of Comparative Example 3 is also relatively low, which is far lower than that of Example 4-Example 6, which may be because the lack of a connecting layer of carboxylated nanocellulose causes the oxidized graphene to be unable to uniformly coat the modified asphalt droplets, resulting in uneven dispersion of the oxidized graphene and the modified asphalt in the electrode paste, easy agglomeration of the oxidized graphene, and thus an increase in defects in the electrode paste, which is manifested as a decrease in the performance of the electrode paste. The performance of the electrode paste prepared in Comparative Example 4 is better than that of Comparative Example 1-Comparative Example 3 and Comparative Example 5, the core of which is unmodified asphalt, and the softening point is lower than that of Example 4-Example 6, which still forms a slight delamination during baking, resulting in less than ideal mechanical performance of the electrode paste, which is manifested as a lower compressive strength of the electrode paste than that of Example 4-Example 6, and the outer layer exists an oxidized graphene layer, so the resistivity test result is relatively good, only next to that of Example 4-Example 6. Comparative Example 5 adds the three components of the modified additive to the electrode paste by physical mixing, and each component exists but is distributed in disorder and agglomerates, which cannot form an effective reinforcing network, resulting in less than ideal performance improvement, and the resistivity and compressive strength test results of the electrode paste are not much different from those of Comparative Example 1.

[0080] The above describes the embodiments of the present application, but the present application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative but not restrictive, and those skilled in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, which all belong to the protection of the present application.

Claims

1. A modified additive, characterized in that, The modified additive has a core-shell structure, with the core being modified asphalt, the modified asphalt being coated with carboxylated nanocellulose as a connecting layer, and the connecting layer being coated with graphene oxide as a shell layer. The connecting layer is formed by coating the modified asphalt surface with carboxylated nanocellulose through emulsification; the shell layer is constructed by hydrogen bonding between graphene oxide and the connecting layer. The modified asphalt is asphalt containing natural latex and nano-silica; The preparation method of the modified additive includes the following steps: Step A1: Add natural latex to asphalt, stir, add nano-silica, mix, and obtain modified asphalt; Step A2: Disperse carboxylated nanocellulose in water, add sodium dodecyl sulfonate to obtain an aqueous phase; add modified asphalt to the aqueous phase and emulsify to obtain a modified asphalt emulsion; Step A3: Disperse graphene oxide in deionized water to obtain graphene oxide dispersion; add graphene oxide dispersion to modified asphalt emulsion, stir, centrifuge, wash the precipitate with deionized water, and vacuum dry to obtain modified additive.

2. The modified additive according to claim 1, characterized in that, The carboxylated nanocellulose is either TEMPO oxidized nanocellulose or carboxymethylated nanocellulose; in the modified asphalt, the mass ratio of natural latex, nano silica and asphalt is 6:(2-4):100; the mass ratio of modified asphalt, carboxylated nanocellulose and graphene oxide is 10:(0.9-1.35):(1-1.8).

3. The method for preparing a modified additive according to claim 1, characterized in that, In step A1, the stirring temperature is 160-170℃, the stirring speed is 2500-3500rpm, and the stirring time is 25-45min; the mixing temperature is 170-180℃, the mixing speed is 3500-4500rpm, and the mixing time is 40-60min.

4. The method for preparing a modified additive according to claim 1, characterized in that, In step A2, the mass ratio of carboxylated nanocellulose, sodium dodecyl sulfonate, and water is (1-1.5):0.1:(98.5-99); the emulsification temperature is 50-60℃, the emulsification speed is 17000-18000 rpm, and the emulsification time is 2-5 min.

5. The method for preparing a modified additive according to claim 1, characterized in that, In step A3, the mass ratio of graphene oxide to deionized water is (1-1.8):(48.2-49); the stirring speed is 400-600 rpm, and the stirring time is 18-24 h; the vacuum drying temperature is 20-30℃, the vacuum drying time is 12-18 h, and the vacuum degree of vacuum drying is less than 10 kPa.

6. An electrode paste based on the modified additive of claim 1 or 2, characterized in that, The electrode paste comprises aggregate, powder, binder and modified additive; the mass ratio of the aggregate, powder, binder and modified additive is (55-65):(15-17):(15-25):(3-5).

7. The method for preparing an electrode paste based on modified additives according to claim 6, characterized in that, Includes the following steps: Step S1: Mix the calcined and pulverized aggregate and powder, add the modifying additive, and dry mix to obtain a mixed dry material; Step S2: Preheat the mixing pot, add the mixed dry materials, add the molten binder, mix and knead to obtain the electrode paste blank; Step S3: Press the electrode paste preform into shape and cure it to obtain electrode paste based on modified additives.

8. The method for preparing an electrode paste based on modified additives according to claim 7, characterized in that, In step S1, the aggregate includes any one or more of anthracite, residual anode, graphite fragments, and calcined petroleum coke; the powder includes any one or more of graphite powder and coke powder; the mixing speed is 100-150 rpm, the mixing time is 10-15 min, and the mixing temperature is 20-30℃; the dry mixing speed is 120-200 rpm, the dry mixing time is 15-20 min, and the dry mixing temperature is 20-30℃.

9. The method for preparing an electrode paste based on modified additives according to claim 7, characterized in that, In step S2, the preheating temperature of the kneading pot is 80-100℃; the binder is medium-temperature coal tar pitch or high-temperature coal tar pitch; the temperature of the molten binder is 100-120℃; the kneading speed is 50-80 rpm, the kneading time is 30-45 min, and the kneading temperature is 110-130℃; in step S3, the pressing pressure is 20-30 MPa, the pressing temperature is 100-120℃; the curing temperature is 25-35℃, and the curing time is 24-48 h.

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