CN117577969A - Application of novel negative electrode additive in improving gradient porosity of negative electrode and preparation method thereof - Google Patents

Application of novel negative electrode additive in improving gradient porosity of negative electrode and preparation method thereof Download PDF

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Publication number
CN117577969A
CN117577969A CN202311497933.1A CN202311497933A CN117577969A CN 117577969 A CN117577969 A CN 117577969A CN 202311497933 A CN202311497933 A CN 202311497933A CN 117577969 A CN117577969 A CN 117577969A
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negative electrode
perforated
electrode plate
liquid
perforated carbon
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曹余良
姜倩荣
艾新平
杨汉西
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Wuhan University WHU
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Wuhan University WHU
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention discloses an application of a novel negative electrode additive in improving gradient porosity of a negative electrode and a preparation method thereof, and belongs to the technical field of electrodes comprising active materials. In the preparation process of the negative electrode plate, the perforated carbon spheres with a perforated structure are used as the negative electrode additive, and the perforated carbon spheres are coated on the surface of the uncompacted negative electrode plate, so that the perforated carbon spheres automatically permeate into gaps of surface particles of the negative electrode plate through capillary action. Through the special hollow structure of the perforated carbon sphere, a lithium ion passage can be effectively constructed even under the condition of overvoltage on the surface of the negative electrode, and the penetrating capacity of lithium ions on the surface layer of the low pore is effectively improved. Meanwhile, the method can effectively solve the problems of lithium precipitation and service life caused by the aggregation of lithium ions on the surface layer in the long-period multiplying power circulation process, and improves the safety and the circulation service life of the battery.

Description

Application of novel negative electrode additive in improving gradient porosity of negative electrode and preparation method thereof
Technical Field
The invention relates to the technical field of electrodes comprising active materials, in particular to application of a novel negative electrode additive in improving gradient porosity of a negative electrode and a preparation method thereof.
Background
As the number of users of electric vehicles increases, the user's demand for charging speed is also increasing. Traditional slow charging mode needs longer time to accomplish the charging, and quick charging can shorten the charge time greatly, improves usability and user experience of vehicle. Therefore, the demand of the new energy automobile for quick charging is mainly hoped to complete charging at a faster speed, save time and improve the use efficiency.
The quick charging technology provides high-speed charging and ensures the safety of the charging process. High temperature, high voltage, etc. may occur during the charging process, and thus corresponding safety measures are necessary to ensure the stability and reliability of the charging process. The need for fast charging by new energy automobile users also includes safety requirements for charging devices and systems, where it is desirable to be able to use strictly tested and certified devices to avoid potential safety risks.
The cathode material plays an important role in the quick charge performance of the battery, and the structure, the surface property and the electrochemical property of the cathode material all influence the lithium ion diffusion, the electrochemical reaction, the electrolyte wettability and the like in the quick charge process. The performance of the cathode material is optimized, so that the quick charge performance of the battery can be improved, and the requirement of a new energy automobile on quick charge is met. Through years of rapid charging research on the negative electrode, most of the improvement work is already a bottleneck, and few improvement schemes for the gradient porosity direction of the negative electrode are still provided.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, in a first aspect of the present invention, there is provided a method for improving gradient porosity of a negative electrode, comprising the steps of: in the preparation process of the negative electrode plate, perforated carbon spheres with perforated structures are used as a negative electrode additive, and the perforated carbon spheres are coated on the surface of the uncompacted negative electrode plate, so that the perforated carbon spheres automatically permeate into gaps of particles on the surface layer of the negative electrode plate through capillary action.
The gradient porosity of the negative electrode can improve the charge and discharge rate of the battery. During rapid battery charge and discharge, lithium ions need to enter and exit the negative electrode material as quickly as possible. However, in a region where the porosity is low, the diffusion rate of lithium ions may be limited, thereby limiting the charge and discharge rate of the battery. The gradient porosity of the negative electrode can provide more active surface area so that lithium ions can more easily enter and exit the negative electrode material, and simultaneously reduce the mechanical stress of the negative electrode material in the charge and discharge process, thereby improving the charge and discharge performance of the battery. According to the invention, through the special hollow structure of the perforated carbon sphere, a lithium ion passage can be effectively constructed even under the condition of overvoltage on the surface of the negative electrode, and the penetration capability of lithium ions on the surface layer with low pores is effectively improved. Meanwhile, the method can effectively solve the problems of lithium precipitation and service life caused by the aggregation of lithium ions on the surface layer in the long-period multiplying power circulation process, and improves the safety and the circulation service life of the battery.
Preferably, the preparation method of the perforated carbon sphere comprises the following steps:
s1, respectively dissolving a high molecular polymer in an organic solvent to obtain a corresponding central liquid and an external liquid for later use;
s2, adopting a coaxial electrostatic spinning process, and obtaining fiber yarns with a core-shell structure by coaxial electrostatic spinning of the central liquid and the outer liquid for later use;
s3, adding the fiber filaments into an organic solvent, dissolving a central core layer and retaining a shell layer through the organic solvent, filtering and collecting a filter cake, and drying the filter cake to obtain a carbon sphere fiber body for later use;
s4, presintering the carbon sphere fiber body in an air atmosphere, and then carbonizing under the protection of inert gas to obtain the perforated carbon sphere.
Further preferably, in S1, the high molecular polymer in the core liquid includes at least one of polymethyl methacrylate, polyethylene, polystyrene, and polyvinyl acetate.
Still further, the concentration of the core liquid is 5wt.% to 10wt.%.
Further preferably, in S1, the high molecular polymer in the external liquid includes at least one of polyamide, polyacrylonitrile, polyvinyl alcohol, and polyvinyl chloride.
Still further, the concentration of the external fluid is 5wt.% to 15wt.%.
Based on the type of high molecular polymer in the central liquid and the outer liquid, the high molecular polymer can be dissolved by adopting an organic solvent suitable in the field, and further the organic solvent comprises at least one of N, N-dimethylformamide, dimethyl furan, dimethyl sulfoxide and N-methylpyrrolidone.
The heating and stirring are helpful for the full dissolution of the high molecular polymer, and uniform and stable central liquid and external liquid are obtained. Further preferably, in the step S1, the dissolution is promoted by heating and stirring at a temperature of 60 to 100 ℃, at a stirring rate of 500 to 2000rpm, and for a treatment time of 5 to 60 minutes.
Further preferably, in S2, parameters of the coaxial electrospinning are as follows: the voltage is 10-30 kV, the pushing rate of the central liquid is 20-500 mL/min, the pushing rate of the outer liquid is 25-250 mL/min, and the electrode distance is 15-30 cm.
The ratio of the advancing rates of the central liquid and the outer liquid influences the performance of the finished product, and the smaller the ratio is, the larger the weight specific gravity of the outer liquid high-molecular polymer is, the smaller the perforation is, the smaller the active surface is, and the better the circulation performance is. Further, the ratio of the pushing rates of the central liquid and the outer liquid is 0.2-2.0.
The organic solvent in step S3 may also be of a type suitable in the art. Further preferably, in S3, the organic solvent includes at least one of toluene, tetrahydrofuran, xylene, and amyl acetate. Likewise, mixing may be performed by heating and stirring. Further preferably, in the step S3, the mixing is promoted by heating and stirring at a temperature of 60 to 100 ℃, at a stirring rate of 200 to 1000rpm, and for a treatment time of 1 to 5 hours.
Further preferably, in S4, the pre-sintering temperature is 200 to 400 ℃ and the treatment time is 1 to 5 hours.
Further preferably, in the step S4, the carbonization temperature is 1200 to 1500 ℃ and the treatment time is 1 to 6 hours.
Preferably, the specific operation of the method for improving the gradient porosity of the negative electrode is as follows: in the preparation process of the negative electrode plate, perforated carbon spheres with perforated structures are used as a negative electrode additive, and the perforated carbon spheres, a conductive agent and a binder are mixed to prepare additive slurry; and coating the additive slurry on the surface of the uncompacted negative electrode plate, so that the perforated carbon spheres automatically permeate into gaps of surface particles of the negative electrode plate through capillary action, and improving the gradient porosity of the negative electrode after compaction.
The choice and proportions of the conductive agent and binder are varied and commercial types common in the art can be used, with SP carbon black and SBR binders being particularly suitable types of conductive agent and binder, respectively.
Coating with a wire bar is a simple and quick form of operation and the amount of surface coating can be controlled by controlling the screen distance of the wire bar. Further preferably, the additive slurry is coated on the surface of the uncompacted negative electrode plate by using a bar, and the reticulation of the bar is 6-30 mu m.
Based on the technical scheme, the method for improving the gradient porosity of the negative electrode takes the perforated carbon sphere with a perforated structure as a novel negative electrode additive, and provides more effective active surfaces and lithium ion channels through the perforation of the center of the carbon sphere, wherein electrolyte enters the perforation; after coating, the carbon spheres penetrate into the surface layer cathode through capillary action, and the carbon spheres are not deformed under cold pressing because of enough rigidity, so that a lithium ion passage can be effectively constructed, and the penetrating capacity of lithium ions on the low-pore surface layer is improved; the construction of the surface lithium ion channel can also effectively improve the problems of lithium precipitation and service life caused by the aggregation of lithium ions on the surface layer in the long-period multiplying power circulation process, and improve the safety and the circulation life of the battery.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the invention provides a method for improving gradient porosity of a negative electrode, which uses a perforated structure as a novel negative electrode additive to be applied to preparation of the negative electrode, optimizes the performance of a negative electrode material and further improves the quick charge performance of a battery.
Drawings
Fig. 1 is a Scanning Electron Microscope (SEM) cross-sectional morphology of an electrode prepared using perforated carbon spheres of example 2.
Detailed Description
The invention is further illustrated by means of the following examples, which are not intended to limit the scope of the invention. The experimental methods, in which specific conditions are not noted in the following examples, were selected according to conventional methods and conditions, or according to the commercial specifications.
Example 1
The method for improving the gradient porosity of the negative electrode comprises the following steps:
in the preparation process of the negative electrode plate, mixing perforated carbon spheres with a perforated structure (accounting for 90 wt.%) with SP carbon black (accounting for 5 wt.%) and SBR binder (accounting for 5 wt.%) to prepare additive slurry; and coating the additive slurry on the surface of the uncompacted negative electrode plate by adopting a bar with a reticulate pattern of 6 mu m, so that the perforated carbon spheres automatically permeate into gaps of particles on the surface layer of the negative electrode plate by capillary action, and compacting to obtain the perforated carbon sphere negative electrode plate.
The preparation method of the perforated carbon sphere in this embodiment is as follows:
s1, adding polymethyl methacrylate into N, N-dimethylformamide, heating and stirring at 500rpm at 60 ℃ for 60min to obtain a central liquid with the concentration of 5 wt%; adding polyamide into N, N-dimethylformamide, heating and stirring at 500rpm at 60deg.C for 60min to obtain 5wt.% external solution;
s2, adopting coaxial electrostatic spinning equipment, setting the voltage to be 10kV, setting the propulsion rate of a central liquid to be 50mL/min, setting the propulsion rate of an external liquid to be 250mL/min, controlling the propulsion rate ratio of the central liquid to be 0.2, setting the electrode distance to be 30cm, and obtaining fiber filaments with a core-shell structure through coaxial electrostatic spinning for later use;
s3, adding the fiber filaments into excessive toluene, stirring at a temperature of 100 ℃ for 1h at a rotating speed of 200rpm to dissolve the inner core, filtering by a suction filtration device, collecting a filter cake, and drying the filter cake to obtain a carbon sphere fiber body for later use;
s4, presintering the carbon sphere fiber body for 5 hours at the temperature of 200 ℃ in an air atmosphere, carbonizing the carbon sphere fiber body for 6 hours at the temperature of 1200 ℃ under the protection of nitrogen, and cooling to obtain the perforated carbon sphere.
Example 2
The method for improving the gradient porosity of the negative electrode comprises the following steps:
in the preparation process of the negative electrode plate, mixing perforated carbon spheres with a perforated structure (accounting for 90 wt.%) with SP carbon black (accounting for 5 wt.%) and SBR binder (accounting for 5 wt.%) to prepare additive slurry; and coating the additive slurry on the surface of the uncompacted negative electrode plate by adopting a bar with a reticulate pattern of 15 mu m, so that the perforated carbon spheres automatically permeate into gaps of particles on the surface layer of the negative electrode plate by capillary action, and compacting to obtain the perforated carbon sphere negative electrode plate.
The preparation method of the perforated carbon sphere in this embodiment is as follows:
s1, adding polyethylene into dimethylfuran, heating and stirring at 1000rpm for 30min at 80 ℃ to obtain a central liquid with the concentration of 8 wt.%; adding polyacrylonitrile into dimethylfuran, heating and stirring at 1000rpm for 30min at 80 ℃ to obtain an external liquid with the concentration of 10wt.% for later use;
s2, adopting coaxial electrostatic spinning equipment, setting the voltage to be 20kV, setting the propulsion rate of a central liquid to be 50mL/min, and setting the propulsion rate of an external liquid to be 50mL/min, so that the propulsion rate ratio of the central liquid to the external liquid is controlled to be 1.0, the electrode distance is 20cm, and obtaining fiber filaments with a core-shell structure through coaxial electrostatic spinning for later use;
s3, adding the fiber filaments into excessive tetrahydrofuran, stirring at the temperature of 80 ℃ for 3 hours at the rotating speed of 600rpm to dissolve the inner core, filtering by a suction filtration device, collecting a filter cake, and drying the filter cake to obtain a carbon sphere fiber body for later use;
s4, presintering the carbon sphere fiber body for 3 hours at the temperature of 300 ℃ in an air atmosphere, carbonizing the carbon sphere fiber body for 3 hours at the temperature of 1300 ℃ under the protection of argon, and cooling to obtain the perforated carbon sphere.
The cross-sectional morphology of the perforated carbon sphere negative electrode plate is observed through a Scanning Electron Microscope (SEM), as shown in fig. 1, the marked size in the graph indicates that the perforated carbon sphere effectively permeates into the gaps of the negative electrode graphite, the pore level of the graphite surface layer is improved, the gradient porosity is built, and the electrical property of the electrode is improved.
Example 3
The method for improving the gradient porosity of the negative electrode comprises the following steps:
in the preparation process of the negative electrode plate, mixing perforated carbon spheres with a perforated structure (accounting for 90 wt.%) with SP carbon black (accounting for 5 wt.%) and SBR binder (accounting for 5 wt.%) to prepare additive slurry; and coating the additive slurry on the surface of the uncompacted negative electrode plate by adopting a bar with a reticulate pattern of 30 mu m, so that the perforated carbon spheres automatically permeate into gaps of particles on the surface layer of the negative electrode plate by capillary action, and compacting to obtain the perforated carbon sphere negative electrode plate.
The preparation method of the perforated carbon sphere in this embodiment is as follows:
s1, adding polystyrene into N-methyl pyrrolidone, heating and stirring at 1500rpm for 5min at 100 ℃ to obtain a central solution with the concentration of 10 wt%; adding polyvinyl alcohol into N-methyl pyrrolidone, heating and stirring at 1500rpm for 5min at 100deg.C to obtain an external solution with concentration of 15wt.% for use;
s2, adopting coaxial electrostatic spinning equipment, setting the voltage to be 30kV, setting the propulsion rate of a central liquid to be 50mL/min, and setting the propulsion rate of an external liquid to be 25mL/min, so that the propulsion rate ratio of the central liquid to the external liquid is controlled to be 2.0, the electrode distance is 15cm, and obtaining fiber filaments with a core-shell structure through coaxial electrostatic spinning for later use;
s3, adding the fiber filaments into excessive dimethylbenzene, stirring at a temperature of 60 ℃ for 5 hours at a rotating speed of 1000rpm to dissolve the inner core, filtering by a suction filtration device, collecting a filter cake, and drying the filter cake to obtain a carbon sphere fiber body for later use;
s4, presintering the carbon sphere fiber body for 1h at the temperature of 400 ℃ in an air atmosphere, carbonizing at the temperature of 1500 ℃ for 1h under the protection of nitrogen, and cooling to obtain the perforated carbon sphere.
Comparative example 1
The negative electrode sheet used in the example was used in this comparative example without any other treatment.
Comparative example 2
This comparative example uses the negative electrode sheet used in the example, replaces the perforated carbon sphere with hard carbon having a D50 of 2.3 μm and completes the coating using the same process.
The effect of the perforated carbon sphere negative electrode pieces prepared in the embodiments 1 to 3 of the invention on improving the rate performance in batteries is studied. Comparative example 1 was a negative electrode sheet used in the examples without any treatment, and comparative example 2 was prepared by replacing perforated carbon spheres with hard carbon, mixing with a conductive agent SP (at 90 wt.%) and a binder SBR (at 5 wt.%), coating the surface of the uncompacted negative electrode sheet with a wire rod having a mesh of 15 μm, and compacting. The negative plates prepared in comparative examples 1 and 2 and examples 1 to 3 are respectively used for preparing 505070 soft-pack batteries (1.7 Ah), commercial lithium iron phosphate positive electrodes are adopted, and the positive and negative formulas and technological parameters of all samples are kept consistent, so that the corresponding soft-pack batteries to be tested are obtained. The D50 of the perforated carbon sphere or hard carbon was tested by a laser particle sizer, and the resultant soft pack battery was each subjected to a rate performance test, the results of which are shown in table 1.
Table 1:
as can be seen from the comparative examples and comparative examples, the rate performance and cycle performance of the examples are much higher than those of the comparative examples after the pole piece is over-pressed. It can be seen that the perforated carbon spheres of the examples are effective in propping open the graphite, providing a higher level of porosity to the graphite surface. An effective ion channel can be constructed even under overpressure conditions.
As can be seen from the comparison of examples and comparative example 2, the hard carbon also has the effect of expanding graphite, but the performance attenuation under overpressure condition is larger than that of the examples because the carbon sphere has no pore passage in the middle. The middle perforation channel of the perforation carbon sphere plays a core role in lithium ion transmission.
The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention by one of ordinary skill in the art without undue burden. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by the person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.

Claims (10)

1. A method for improving gradient porosity of a negative electrode, comprising the steps of: in the preparation process of the negative electrode plate, perforated carbon spheres with perforated structures are used as a negative electrode additive, and the perforated carbon spheres are coated on the surface of the uncompacted negative electrode plate, so that the perforated carbon spheres automatically permeate into gaps of particles on the surface layer of the negative electrode plate through capillary action.
2. The method of claim 1, wherein the perforated carbon sphere is prepared by the following method:
s1, respectively dissolving a high molecular polymer in an organic solvent to obtain a corresponding central liquid and an external liquid for later use;
s2, adopting a coaxial electrostatic spinning process, and obtaining fiber yarns with a core-shell structure by coaxial electrostatic spinning of the central liquid and the outer liquid for later use;
s3, adding the fiber filaments into an organic solvent, dissolving a central core layer and retaining a shell layer through the organic solvent, filtering and collecting a filter cake, and drying the filter cake to obtain a carbon sphere fiber body for later use;
s4, presintering the carbon sphere fiber body in an air atmosphere, and then carbonizing under the protection of inert gas to obtain the perforated carbon sphere.
3. The method according to claim 2, characterized in that: in the step S1, the high molecular polymer in the central liquid comprises at least one of polymethyl methacrylate, polyethylene, polystyrene and polyvinyl acetate; the high molecular polymer in the external liquid comprises at least one of polyamide, polyacrylonitrile, polyvinyl alcohol and polyvinyl chloride; the organic solvent comprises at least one of N, N-dimethylformamide, dimethyl furan, dimethyl sulfoxide and N-methylpyrrolidone.
4. A method according to claim 3, characterized in that: the concentration of the central liquid is 5wt.% to 10wt.%, and the concentration of the outer liquid is 5wt.% to 15wt.%.
5. The method according to claim 2, characterized in that: in the step S1, the dissolution is promoted by heating and stirring, the temperature of the heating and stirring is 60-100 ℃, the stirring speed is 500-2000 rpm, and the treatment time is 5-60 min.
6. The method according to claim 2, characterized in that: in the step S2, parameters of the coaxial electrostatic spinning are as follows: the voltage is 10-30 kV, the pushing rate of the central liquid is 20-500 mL/min, the pushing rate of the outer liquid is 25-250 mL/min, the pushing rate ratio of the central liquid and the outer liquid is 0.2-2.0, and the electrode distance is 15-30 cm.
7. The method according to claim 2, characterized in that: in the step S3, the organic solvent comprises at least one of toluene, tetrahydrofuran, xylene and amyl acetate; the mixing is promoted by heating and stirring, the temperature of the heating and stirring is 60-100 ℃, the stirring speed is 200-1000 rpm, and the treatment time is 1-5 h.
8. The method according to claim 2, characterized in that: in the step S4, the temperature of the presintered is 200-400 ℃ and the treatment time is 1-5 h; the carbonization temperature is 1200-1500 ℃, and the treatment time is 1-6 h.
9. The method according to claim 1, characterized by the specific operation of: in the preparation process of the negative electrode plate, perforated carbon spheres with perforated structures are used as a negative electrode additive, and the perforated carbon spheres, a conductive agent and a binder are mixed to prepare additive slurry; and coating the additive slurry on the surface of the uncompacted negative electrode plate, so that the perforated carbon spheres automatically permeate into gaps of surface particles of the negative electrode plate through capillary action, and improving the gradient porosity of the negative electrode after compaction.
10. The method according to claim 9, wherein: and (3) coating the additive slurry on the surface of the uncompacted negative electrode plate by adopting a bar, wherein the reticulate pattern of the bar is 6-30 mu m.
CN202311497933.1A 2023-11-09 2023-11-09 Application of novel negative electrode additive in improving gradient porosity of negative electrode and preparation method thereof Pending CN117577969A (en)

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