CN116435451A - Silicon-oxygen-graphite mixed negative electrode conductive slurry, preparation method thereof and negative electrode plate - Google Patents

Silicon-oxygen-graphite mixed negative electrode conductive slurry, preparation method thereof and negative electrode plate Download PDF

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CN116435451A
CN116435451A CN202310485961.5A CN202310485961A CN116435451A CN 116435451 A CN116435451 A CN 116435451A CN 202310485961 A CN202310485961 A CN 202310485961A CN 116435451 A CN116435451 A CN 116435451A
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slurry
stirring
negative electrode
graphite
silicon
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蔡美慧
王衍
宋明
饶绍建
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Wanxiang A123 Systems Asia Co Ltd
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Abstract

The application discloses a silicon-oxygen-graphite mixed negative electrode conductive paste, a preparation method thereof and a negative electrode plate, and relates to the technical field of lithium ion batteries, and the preparation method comprises the following steps: placing the winding type carbon nano tube slurry and the silicon oxide material into a first stirrer for stirring to obtain first slurry; adding the array type carbon nano single-arm tube slurry into the first slurry, and stirring to obtain second slurry; adding CMC glue solution and deionized water into the second stirrer to stir so as to obtain third slurry; adding the second slurry into the third slurry, and stirring to obtain fourth slurry; adding graphite into a third stirrer for dry mixing with the conductive carbon black in two times to obtain first mixed powder; adding the fourth slurry into the first mixed powder for stirring in two times to obtain a fifth slurry; and adding the styrene-butadiene rubber emulsion into the fifth slurry, and stirring to obtain the mixed negative electrode conductive slurry. The method ensures conductivity stability, is low in cost, greatly shortens mixing process time and improves production efficiency.

Description

Silicon-oxygen-graphite mixed negative electrode conductive slurry, preparation method thereof and negative electrode plate
Technical Field
The application relates to the technical field of lithium ion batteries, in particular to silicon-oxygen-graphite mixed negative electrode conductive paste, a preparation method thereof and a negative electrode plate.
Background
Silicon-based negative electrodes are always the focus of research and development and attention as key materials for improving the dynamic energy density of next generation new energy sources. Since silicon materials are easily expanded, a large volume change may cause breakage and pulverization of silicon particles, thereby affecting battery performance. The volume expansion of the silicon oxide material is small compared with that of pure silicon, but the silicon oxide material still has the defects of low first efficiency, poor conductivity, large volume expansion and the like; the lithium ion is preferentially reacted with silicon to generate Li2O, li SiO4 in the process of embedding the silicon-oxygen negative electrode material, and the two substances have the effect of preventing the expansion effect of silicon in the process of removing the lithium, so that the cycle stability and the service life of the lithium ion are improved compared with those of a pure silicon material, but the lithium ion is also low in first cycle efficiency and poor in conductivity due to the fact that irreversible Li2O, li SiO4 is generated; in addition, the silicon oxide anode material still has a problem of large volume expansion as compared with the graphite material. In addition, the SEI film on the surface is unstable due to expansion, and the silicon oxide material has lower conductivity, so that the application of the SEI film in a lithium ion battery is restricted to a certain extent.
At present, the main scheme is that a silicon oxygen material is mixed with graphite, and a conductive agent with good conductivity, such as a carbon tube, is added to enhance conductivity, so as to prepare the mixed negative electrode. For example, the patent application CN115395015A adopts the steps of mixing and stirring a carbon-based material with a certain mass and a titanium source, centrifugally drying and calcining at a high temperature to obtain composite powder; and (3) weighing a certain mass of dispersing agent, adding the dispersing agent into deionized water, stirring to fully dissolve the dispersing agent to obtain a dispersion system, adding a certain mass of compound powder into the dispersion system, stirring, and finally performing ultrasonic dispersion and sand mill treatment to obtain the uniformly dispersed conductive paste. The composite conductive slurry formed by the carbon-based material and the titanium dioxide can be applied to a silicon oxide negative electrode, and the specific capacity, the first coulomb efficiency and the cycling stability of the composite conductive slurry are effectively improved; according to the technical scheme, a titanium source is added to prepare silicon oxide coated with an amorphous titanium dioxide layer, and conventional negative electrode proportioning is further carried out to prepare a pole piece; wherein the titanium dioxide layer may enhance ion mobility. In the actual operation process, the uniformity of the titanium dioxide coating on the silica material is difficult to ensure the interface stability; and the existing coating technology has limited effect on improving the ion mobility.
For example, in the patent application CN114388748A, the silicon-based negative electrode and the linear conductive agent are mixed first, so that the linear conductive agent is uniformly wrapped on the surface of the silicon-based negative electrode, the volume expansion effect of the silicon-based negative electrode is effectively relieved by wrapping the linear conductive agent, and meanwhile, the linear conductive agent is further mixed with the glue solution formed by the dot-shaped conductive agent, so that the paste is more dispersed uniformly, a more perfect three-dimensional conductive network structure is formed, and the electronic conductivity of the silicon-carbon negative electrode is further improved. However, the technical scheme is that 10% of conductive carbon black is added into CMC for stirring, then 5% of silicon oxide and 1% of carbon nano tube as negative electrode active materials are sequentially added, and finally 95% of graphite negative electrode powder as negative electrode active materials are added; wherein 10% of conductive carbon black is high in proportion and difficult to disperse, and is easy to locally agglomerate when being dispersed with graphite in the later stage, so that the charge and discharge are uneven in the later stage, and the performance is influenced.
And as in patent application CN115663188A, carbon nanotube 0.55-3 wt%, dispersant 0.1-1 wt% and solvent for the rest; the carbon nano tube comprises the following components in percentage by mass (50-70): (30-50) short carbon nanotubes containing hydroxyl groups and long carbon nanotubes containing carboxyl groups; the length-diameter ratio of the short carbon nano tube is (50-2500): 1, a step of; the length-diameter ratio of the long carbon nano tube is (3000-143000): 1. the short carbon nano tube with low length-diameter ratio and the long carbon nano tube with high length-diameter ratio and the carboxyl are subjected to grading, short-range electronic conduction and long-range electronic conduction are realized at the same time, a three-dimensional electric conduction network is perfected, the electric conductivity of the silicon-based negative electrode material is improved, the uniform distribution of electrolyte is promoted, and the volume expansion effect of the silicon-based negative electrode is effectively relieved. However, the technical method needs ball milling and crushing to prepare short carbon nanotube slurry, a high-pressure homogenizer disperses long carbon nanotube slurry, and finally the short carbon nanotube slurry is mixed with silicon oxide, a binder and a dispersing agent to prepare the cathode slurry. The whole operation flow has longer time and lower efficiency; and the dispersion uniformity of the long/short carbon nanotubes cannot be ensured; this is detrimental to the process production. And the multi-arm carbon tube is selected, so that the improvement effect on the conductivity of the silicon-oxygen cathode is limited.
Disclosure of Invention
The preparation method aims to solve the problems of long batching process time, high cost and serious winding of the carbon nano tube in batching in the prior art; the technical scheme provided by the application is that when the cathode is used for batching, the carbon tube is partially premixed and then mixed with the well-dispersed conductive carbon black/graphite mixture, so that the carbon tube can be better dispersed, and meanwhile, the batching process time is shortened; the array type carbon nano single-arm tube and the winding type carbon nano tube are arranged in parallel, and the good orientation leads to low winding degree and easy dispersion, so that various characteristics caused by the huge length-diameter ratio can be better exerted; meanwhile, the cost of the conductive agent can be adjusted by the combination of the winding type and the array type.
Specifically, in order to achieve the above technical solution, in a first aspect, the present application provides a method for preparing a silicon-oxygen-graphite mixed anode conductive paste, including the following steps:
mixing and stirring the winding type carbon nano tube slurry and a silicon oxygen material to obtain first slurry;
adding the array type carbon nano single-arm tube slurry into the first slurry, and stirring to obtain second slurry;
mixing and stirring CMC glue solution and deionized water to obtain third slurry; adding the second slurry into the third slurry, and stirring to obtain fourth slurry;
dividing graphite into two parts, and dry-mixing the graphite and the conductive carbon black twice to obtain first mixed powder;
equally dividing the fourth slurry into two parts, adding the fourth slurry into the first mixed powder for stirring in two times to obtain fifth slurry;
and adding the styrene-butadiene rubber emulsion into the fifth slurry, and stirring to obtain the mixed negative electrode conductive slurry.
Preferably, the stirring speed of the first slurry is 2000RPM/min of rotation speed, 30RPM/min of revolution speed, and the stirring time required for the first slurry is 30 minutes; the stirring speed of the second slurry, the third slurry and the fourth slurry is the same as that of the first slurry, the stirring time of the second slurry is 30 minutes, the stirring time of the third slurry is 180 minutes, and the stirring time of the fourth slurry is 60 minutes.
Preferably, CMC accounts for 1% -5% of the mass of the mixed cathode conductive paste.
Preferably, the mass ratio of the winding type carbon nano tube to the mixed negative electrode conductive paste is 0.035-0.14%, and the mass ratio of the array type carbon nano single-arm tube to the mixed negative electrode conductive paste is 0.015-0.06%.
Preferably, the stirring speed is 1000RPM/min for the first graphite addition, 10RPM/min for revolution, and 10 minutes for the second graphite addition, the stirring speed and time are the same as those for the first graphite addition.
Preferably, the stirring speed is 2000RPM/min for the first addition of the fourth slurry, 30RPM/min for the revolution, and 30 minutes for the second addition of the fourth slurry, the stirring speed is the same as the first addition, and 60 minutes for the second addition of the fourth slurry.
Preferably, the stirring speed of the mixed cathode conductive paste is 1000RPM/min of rotation speed, 15RPM/min of revolution speed, the stirring time required for the mixed cathode conductive paste is 30 minutes, and the discharging viscosity of the mixed cathode conductive paste is 3500-4500 Pa.s.
Preferably, the anode active material comprises silicon oxide material and graphite, the mass ratio of the anode active material to the mixed anode conductive paste is 83.3% -96.65%, and the mass ratio of the silicon oxide material to the graphite in the anode active material is 4% -20%: 80 to 96 percent of conductive carbon black accounts for 0.5 to 1.5 percent of the mass of the mixed negative electrode conductive paste, and the mass of the styrene-butadiene rubber accounts for 1.8 to 10 percent of the mass of the mixed negative electrode conductive paste.
In a second aspect, the application provides a silicon-oxygen-graphite mixed negative electrode conductive paste, which is prepared by the preparation method of the silicon-oxygen-graphite mixed negative electrode conductive paste provided by any embodiment of the application.
In a third aspect, the application provides a negative electrode plate, wherein the silicon-oxygen-graphite mixed negative electrode conductive paste provided by any embodiment of the application is coated on a current collector, and the negative electrode plate is obtained by drying.
The application has the following beneficial effects: according to the method, through the compound use of the winding carbon nano tube and the array carbon nano single-arm tube and the matching of the granular conductive agent, a 'point-line-plane' conductive network structure is constructed, and good conductivity is still maintained after the volume expansion of the silicon-oxygen negative electrode is ensured; meanwhile, compared with a single array type carbon nano single-arm tube, the method has the price advantage, is a better matching mode at present for the use of a silicon oxygen cathode and a carbon nano tube conductive agent, is compounded and used in a winding type and array type, and can adjust the cost of the conductive agent; when the cathode material is prepared, the carbon tube is partially premixed, and then the carbon tube is mixed with the dispersed conductive carbon black and graphite mixture, so that the carbon black and the graphite mixture can be better dispersed, the material preparation process time is shortened, and the production efficiency is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application, illustrate and explain the application and are not to be construed as limiting the application.
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic flow chart of a preparation method of a silicon-oxygen-graphite mixed anode conductive paste according to an embodiment of the application;
fig. 2 is a schematic structural diagram of a silicon-oxygen-graphite mixed negative electrode conductive paste before expansion according to an embodiment of the application;
fig. 3 is a schematic structural diagram of an expanded silicon-oxygen-graphite mixed negative electrode conductive paste according to an embodiment of the present application.
Reference numerals:
1. conductive carbon black; 2. graphite; 3. a silicon oxygen material; 4. winding type carbon nano-tubes; 5. array type carbon nanometer single-arm tube.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application; it is apparent that the described embodiments are only a part of the embodiments of the present application, not all of the embodiments, and all other embodiments obtained by a person having ordinary skill in the art without making creative efforts based on the embodiments in the present application are within the scope of protection of the present application.
In the description of the present application, the terms "first," "second," and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The following English abbreviations have Chinese meanings
CMC: sodium carboxymethyl cellulose; HPPC: the HPPC test is carried out on the battery, specifically, the 5-second discharging power and the 5-second charging power of the battery are determined at intervals of 15% SOC, and the 5-second charging power of the battery is determined at intervals of 15% SOC; DCR: a direct current impedance; SBR: styrene-butadiene rubber; SOC: state of charge to reflect the remaining capacity of the battery; negative electrode active material: including silicone materials and graphite.
Referring to fig. 1, in a preferred embodiment of the present application, a method for preparing a silicon-oxygen-graphite mixed anode conductive paste includes the following steps:
s1: placing the winding type carbon nano tube 4 slurry and the silicon oxygen material 3 into a first stirrer for stirring to obtain first slurry;
in the step, the first stirrer is a double-planetary stirrer, the mass ratio of the winding carbon nano tube 4 is 0.035-0.14%, the mass ratio of the silicon oxygen material 3 in the cathode active material is 4-20%, and in the step, the rotation speed of the double-planetary stirrer is 2000RPM/min, the revolution speed is 30RPM/min, and stirring and dispersing are required for 30min.
S2: adding the slurry of the array type carbon nano single-arm tube 5 into the first slurry, and stirring to obtain second slurry;
in the step, the mass ratio of the array type carbon nano single-arm tube 5 is 0.015-0.06%, and the rotation speed of the double-planetary stirrer in the step is 2000RPM/min, the revolution speed is 30RPM/min, and stirring and dispersing are required for 30min.
S3: adding CMC glue solution and deionized water into the second stirrer to stir so as to obtain third slurry; adding the second slurry into the third slurry, and stirring to obtain fourth slurry;
in the step, the CMC mass ratio in CMC glue solution is 1% -5%, CMC glue solution and CMC glue in deionized water are mixed and contain 1% -2%, the rest is solvent, the second stirrer is a double-planetary stirrer, the rotation speed of the double-planetary stirrer in the step is 2000RPM/min, the revolution speed is 30RPM/min, the third slurry is required to be stirred for 180min, and the fourth slurry is required to be stirred for 60min.
S4: dividing graphite 2 into two parts equally, adding the graphite 2 into a third stirrer for dry mixing with conductive carbon black 1 in two times to obtain first mixed powder;
in the step, the third stirrer is a double-planetary stirrer, the mass ratio of the negative electrode active material to the mixed negative electrode conductive paste is 83.3-96.65%, the mass ratio of graphite 2 to the negative electrode active material is 80-96%, the mass ratio of conductive carbon black 1 is 0.5-1.5%, the graphite 2 is equally divided into two parts, and the two parts are mixed with the conductive carbon black 1, and when the first mixing is carried out, the rotation speed of the stirrer is 1000RPM/min, the revolution speed is 10RPM/min, and the stirring time is 10min; and in the second mixing process, pouring the rest graphite 2, and continuously stirring and dispersing for 10min at the rotation speed of 1000RPM/min and the revolution speed of 10RPM/min by using a stirrer to obtain first mixed powder.
S5: equally dividing the fourth slurry into two parts, adding the fourth slurry into the first mixed powder for stirring in two times to obtain fifth slurry;
in this step, in step S4, the fourth slurry is equally divided into two parts, and is sequentially mixed with the first mixed powder, and when the first mixed powder is mixed, the rotation speed of the mixer is 2000RPM/min, the revolution speed is 30RPM/min, the stirring time is 30min, then the remaining half of the slurry is poured, the stirring speed is unchanged, and the fifth slurry is obtained by stirring and dispersing for 60 minutes.
S6: and adding the styrene-butadiene rubber emulsion into the fifth slurry, and stirring to obtain the mixed negative electrode conductive slurry.
In the step, the SBR emulsion accounts for 1.8% -10% of the mass of SBR, a stirrer is used for stirring and dispersing for 30min at revolution speed of 15RPM/min and rotation speed of 1000RPM/min, and the mixed negative electrode conductive paste is obtained, and the viscosity of the mixed negative electrode conductive paste is 3500-4500 Pa.s.
Examples 1, 2, 3 and 4 comparative example 1 each had the premise of producing 10kg of negative electrode slurry.
Example 1
Adding a silicon oxygen material 3 (accounting for 4 percent of the cathode active material and accounting for 3.82 percent of the mixed cathode conductive paste) into winding type carbon nano tube paste (the winding type carbon nano tube 4 accounts for 0.035 percent) to be stirred/dispersed at a high speed for 30min to obtain a first paste, and then adding array type carbon nano single-arm tube paste (the array type carbon nano single-arm tube 5 accounts for 0.025 percent) to be stirred/dispersed at a high speed for 30min to obtain a mixed conductive paste (a second paste);
b, simultaneously carrying out the step a, namely taking CMC glue solution (the mass ratio is 1.2%) and a certain amount of deionized water, and stirring/dispersing at a high speed for 3 hours to obtain white glue (third slurry); adding the conductive paste (second paste) stirred/dispersed in the step a, and stirring/dispersing at a high speed for 1h to obtain conductive black glue (fourth paste);
step c, simultaneously carrying out the step a/b, namely taking graphite 2 (the graphite accounts for 91.62 percent of the mixed cathode conductive paste), equally dividing the graphite 2 into two parts, firstly stirring/dispersing one part of graphite and the conductive carbon black 1 (the mass ratio is 1 percent) at a low speed for 10 minutes, adding the rest of graphite 2, and continuously stirring/dispersing at the low speed for 10 minutes; obtaining conductive dry powder (first mixed powder);
step d, adding half of the total amount of the conductive black glue (fourth slurry) in the step b into the conductive dry powder (first mixed powder) in the step c, and stirring/dispersing at a high speed for 30min; adding the rest half, stirring at high speed for 60min to obtain fifth slurry, measuring viscosity of the slurry, and adding appropriate amount of water for viscosity adjustment to make the viscosity meet the standard;
and e, adding SBR (the mass ratio is 2.3%) into the mixture, stirring/dispersing the mixture for 30 minutes at a low speed, vacuumizing the mixture, removing bubbles to obtain experimental slurry (mixed negative electrode conductive slurry), and taking the experimental slurry to perform a subsequent process to prepare the pole piece and the VDA60Ah battery cell.
Example 2
Adding a silicon oxygen material 3 (accounting for 4 percent of the cathode active material and accounting for 3.82 percent of the mixed cathode conductive paste) into a winding type carbon nano tube paste (the winding type carbon nano tube 4 accounts for 0.035 percent) to be stirred/dispersed at a high speed for 30min to obtain a first paste, and then adding an array type carbon nano single-arm tube paste (the array type carbon nano single-arm tube 5 accounts for 0.015 percent) to be stirred/dispersed at a high speed for 30min to obtain a mixed conductive paste (a second paste);
b, simultaneously carrying out the step a, namely taking CMC glue solution (the mass ratio is 1.2%) and a certain amount of deionized water, and stirring/dispersing at a high speed for 3 hours to obtain white glue (third slurry); adding the conductive paste well stirred/dispersed in the mixed conductive paste, and stirring/dispersing at high speed for 1h to obtain conductive black glue (fourth paste);
step c, simultaneously carrying out the step a/b, namely taking graphite 2 (the graphite accounts for 91.63 percent of the mixed cathode conductive paste), equally dividing the graphite 2 into two parts, firstly stirring/dispersing one part of graphite and the conductive carbon black 1 (the mass ratio is 1 percent) at a low speed for 10 minutes, adding the rest of graphite 2, and continuously stirring/dispersing at the low speed for 10 minutes; obtaining conductive dry powder (first mixed powder);
step d, adding half of the total amount of the conductive black glue (fourth slurry) in the step b into the conductive dry powder (first mixed powder) in the step c, and stirring/dispersing at a high speed for 30min; adding the rest half, stirring at high speed for 60min to obtain fifth slurry, measuring viscosity of the slurry, and adding appropriate amount of water for viscosity adjustment to make the viscosity meet the standard;
and e, adding SBR (the mass ratio is 2.3%) into the mixture, stirring/dispersing the mixture for 30 minutes at a low speed, vacuumizing the mixture to remove bubbles to obtain experimental slurry (mixed cathode conductive slurry), and carrying out a subsequent process to prepare the pole piece and the VDA60Ah battery cell.
Example 3
The silicon oxygen material 3 in the embodiment 1 is replaced by 20% in the cathode active material, 0.035% in the winding carbon nano tube 4 is replaced by 0.14% in the mass ratio, 0.025% in the mass ratio of the array carbon nano single-arm tube 5 is replaced by 0.06% in the mass ratio of the CMC glue solution is replaced by 5% in the mass ratio of 1.2, 80% in the cathode active material is replaced by 96% in the graphite 2, 10% in the SBR mass ratio and 83.3% in the cathode active material, and other steps are unchanged, so as to obtain experimental slurry, and the electrode plate and the VDA60Ah cell are manufactured by the subsequent process.
Example 4
The silicon oxygen material 3 in the embodiment 1 is only replaced by 0.015 percent by 0.025 percent by 4 percent by weight of wound carbon nano tubes, 1.2 percent by 1.015 percent by weight of array carbon nano single-arm tubes, 96 percent by weight of graphite 2 in the anode active material, 1.8 percent by weight of SBR, 96.65 percent by weight of anode active material and the like, and the experimental slurry is obtained by the following steps, and the pole piece and VDA60Ah battery cell are manufactured by the following process.
Comparative example 1
Step a, adding deionized water and CMC (the mass ratio is 1.2%), and stirring/dispersing at high speed for 3h to obtain white glue;
step b, adding conductive carbon black 1 (the mass ratio is 1%) into the white glue in the step a, and telling to stir/disperse for 1h;
step c, in the step b, adding the slurry of the array type carbon nano single-arm tube (the array type carbon nano single-arm tube accounts for 0.05 percent) into the slurry, and stirring/dispersing the slurry for 1h at a high speed to obtain the conductive black glue;
step d, the proportion of the negative electrode active material is 96.65%; adding a silicon oxide material 3 (accounting for 4 percent of the main material of the specific activity and accounting for 3.82 percent of the mixed cathode conductive paste) into the c, and stirring and dispersing at a high speed for 1h;
step e, taking graphite 2 (the graphite accounts for 91.63 percent of the mixed cathode conductive paste), equally dividing the graphite 2 into two parts, adding one part of the graphite 2 into the two parts of the mixed cathode conductive paste, stirring at a high speed for 30min, and adding the other part of the graphite 2 into the mixed cathode conductive paste, stirring at a high speed for 3h; measuring the viscosity of the slurry, and adding a proper amount of water to adjust viscosity so that the viscosity meets the standard;
and f, adding SBR (the mass ratio is 2.3%) into the mixture, stirring/dispersing the mixture at a low speed for 30 minutes, vacuumizing and removing bubbles to obtain experimental slurry, and carrying out a subsequent process to prepare the pole piece and the VDA60Ah battery cell.
The dosing process times of example 1, example 2 and comparative example 1 were recorded and the negative pole piece costs made using the experimental slurries of example 1, example 2 and comparative example 1 were accounted for and the corresponding sheet resistances were measured, as detailed in table 1.
Table 1: example 1, example 2 and comparative example 1 formulation process time, cathode cost and sheet resistance
Figure BDA0004208599480000081
Figure BDA0004208599480000091
The same batch of laboratory positive pole pieces was used for the three experiments. The experimental result shows that the film resistance difference is not large, and the influence of the winding type carbon nano tube to the pole piece resistance is not large by replacing part of the array type carbon nano single-arm tube with the winding type carbon nano tube; the carbon tube is compounded and used, so that the cost of the cathode can be reduced, and the cost of the single-arm tube and the multi-arm tube is based on the current price. The embodiment of the application can also save batching time, which is greatly advantageous for post-process improvement.
Table 2:60Ah cell HPPC 30s charging DCR (Unit/mΩ)
SOC Comparative example 1 Example 1 Example 2
95％ 1.465 1.476 1.515
80％ 1.404 1.414 1.448
65％ 1.360 1.370 1.405
50％ 1.374 1.385 1.424
35％ 1.355 1.366 1.402
20％ 1.460 1.471 1.540
Three groups of experimental data show that the overall difference of 30s charging DCR is not great; the method shows that the compound use of the carbon tube has no influence on DCR basically compared with the direct use of the array type carbon nano single-arm tube; even at high SOC, the difference in DCR of the present application is not large when the anode expansion is maximum; referring to fig. 2 specifically, fig. 2 is a schematic structural diagram of the slurry before expansion, as can be seen from fig. 2, the carbon tube is compounded and used together with the granular conductive agent to construct a "point-line-plane" conductive network structure, and after the later volume expansion, as shown in fig. 3, a better conductive network structure can be maintained, and referring to fig. 3 specifically, fig. 3 is a schematic structural diagram of the slurry after expansion, which shows that the compounded and used carbon tube can completely replace the single-arm carbon nano tubes of the array type and simultaneously can save the cost.
The above is only a preferred embodiment of the present application; the scope of protection of the present application is not limited in this respect. Any person skilled in the art, within the technical scope of the present disclosure, shall cover the protection scope of the present application by making equivalent substitutions or alterations to the technical solution and the improved concepts thereof.

Claims (10)

1. The preparation method of the silicon-oxygen-graphite mixed negative electrode conductive slurry is characterized by comprising the following steps of:
mixing and stirring the winding type carbon nano tube slurry and a silicon oxygen material to obtain first slurry;
adding the array type carbon nano single-arm tube slurry into the first slurry, and stirring to obtain second slurry;
mixing and stirring CMC glue solution and deionized water to obtain third slurry; adding the second slurry into the third slurry, and stirring to obtain fourth slurry;
dividing graphite into two parts, and dry-mixing the graphite and the conductive carbon black twice to obtain first mixed powder;
equally dividing the fourth slurry into two parts, adding the fourth slurry into the first mixed powder for stirring in two times to obtain fifth slurry;
and adding the styrene-butadiene rubber emulsion into the fifth slurry, and stirring to obtain the mixed negative electrode conductive slurry.
2. The method for preparing the silicon-oxygen-graphite mixed cathode conductive paste according to claim 1, wherein stirring or dry mixing is carried out by a stirrer, wherein the stirring speed of the first paste is 2000RPM/min at autorotation speed and 30RPM/min at revolution speed, and the stirring time required by the first paste is 30 minutes; the stirring speed of the second slurry, the third slurry and the fourth slurry is the same as that of the first slurry, the stirring time of the second slurry is 30 minutes, the stirring time of the third slurry is 180 minutes, and the stirring time of the fourth slurry is 60 minutes.
3. The preparation method of the silicon-oxygen-graphite mixed negative electrode conductive paste according to claim 1 or 2, wherein the mass ratio of CMC in the mixed negative electrode conductive paste is 1% -5%.
4. The method for preparing the silicon-oxygen-graphite mixed cathode conductive paste according to claim 3, wherein the mass ratio of the winding carbon nano-tube to the mixed cathode conductive paste is 0.035-0.14%, and the mass ratio of the array carbon nano-single-arm tube to the mixed cathode conductive paste is 0.015-0.06%.
5. The method for preparing a silicon-oxygen-graphite mixed negative electrode conductive paste according to claim 4, wherein the stirring speed is 1000RPM/min for the first time of adding the graphite, 10RPM/min for revolution, and 10 minutes for the second time of adding the graphite, and the stirring speed and time are the same as those of the first time.
6. The method for preparing the silicon-oxygen-graphite mixed cathode conductive paste according to claim 1, wherein when the fourth paste is added for the first time, the stirring speed is 2000RPM/min at the rotation speed, 30RPM/min at the revolution speed, and the stirring time is 30 minutes, and when the fourth paste is added for the second time, the stirring speed is the same as that of the first time, and the stirring time is 60 minutes.
7. The method for preparing the silicon-oxygen-graphite mixed cathode conductive paste according to claim 6, wherein the stirring speed of the mixed cathode conductive paste is 1000RPM/min, the revolution speed is 15RPM/min, the stirring time required by the mixed cathode conductive paste is 30 minutes, and the discharging viscosity of the mixed cathode conductive paste is 3500-4500 Pa.
8. The method for preparing a silicon-oxygen-graphite mixed anode conductive paste according to claim 4, wherein an anode active material comprises the silicon-oxygen material and the graphite, the mass ratio of the anode active material to the mixed anode conductive paste is 83.3% -96.65%, and the mass ratio of the silicon-oxygen material to the graphite in the anode active material is 4% -20%: 80 to 96 percent of conductive carbon black accounts for 0.5 to 1.5 percent of the mass of the mixed negative electrode conductive paste, and styrene-butadiene rubber accounts for 1.8 to 10 percent of the mass of the mixed negative electrode conductive paste.
9. A silicon-oxygen-graphite mixed negative electrode conductive paste, which is characterized by being prepared by the preparation method of the silicon-oxygen-graphite mixed negative electrode conductive paste in any one of claims 1-8.
10. A negative electrode plate, characterized in that the silicon-oxygen-graphite mixed negative electrode conductive slurry in claim 9 is coated on a current collector, and the negative electrode plate is obtained by drying.
CN202310485961.5A 2023-04-28 2023-04-28 Silicon-oxygen-graphite mixed negative electrode conductive slurry, preparation method thereof and negative electrode plate Pending CN116435451A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117551348A (en) * 2024-01-11 2024-02-13 湖南科晶新能源科技有限公司 Carbon nano tube composite polyaniline material, heat conducting coating and preparation method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117551348A (en) * 2024-01-11 2024-02-13 湖南科晶新能源科技有限公司 Carbon nano tube composite polyaniline material, heat conducting coating and preparation method

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