CN114792782A - Low-expansion silicon negative electrode material - Google Patents

Low-expansion silicon negative electrode material Download PDF

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CN114792782A
CN114792782A CN202110093876.5A CN202110093876A CN114792782A CN 114792782 A CN114792782 A CN 114792782A CN 202110093876 A CN202110093876 A CN 202110093876A CN 114792782 A CN114792782 A CN 114792782A
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silicon
carbon
pores
nano
negative electrode
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陈青华
刘江平
姚林林
房冰
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Lanxi Zhide New Energy Materials Co ltd
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Lanxi Zhide New Energy Materials Co ltd
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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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite

Abstract

The application provides a low-expansion silicon negative electrode material which comprises porous carbon, nano-silicon, conductive carbon and an ion conductor material, wherein the pores of the porous carbon comprise open pores and closed pores; the proportion of the open pores is 80-99.9% based on the total amount of the open pores and the closed pores being 100%. The porous carbon provides a continuous conductive channel, closed pores can buffer partial volume expansion, open pores are used for containing nano silicon materials, partial pores are reserved for further relieving the volume expansion, and the low expansion rate of the materials is ensured; the nano silicon ensures high specific capacity of the material, the conductive carbon further improves the electronic conductivity of the material, and the ion conductor can provide more ion conducting channels, and simultaneously isolate electrolyte to prevent side reaction. The silicon negative electrode material provided by the application has the advantages of low expansion rate, excellent cycle performance and rate capability.

Description

Low-expansion silicon negative electrode material
Technical Field
The invention belongs to the field of battery materials, and particularly relates to a low-expansion silicon negative electrode material.
Background
In recent years, to meet the demand for multi-functionalization of products, people have increasingly high requirements on the performance of battery such as endurance, safety, quick charge and the like. The silicon material has the advantages of high specific capacity, good safety, rich raw material sources and the like, and is considered as a novel high-performance lithium ion battery cathode material. However, the silicon material generates huge volume expansion due to lithium alloying in the charging and discharging process, which causes pulverization failure of silicon active particles, and simultaneously, the cracking and pulverization of the silicon particles cause poor electrical contact between active particles and current collectors to form an island effect, and the fracture surface repeatedly forms a new SEI film to induce the problem of irreversible capacity continuous loss, thereby restricting the industrial application of the silicon-based material.
Disclosure of Invention
In order to solve the problems, the application provides a low-expansion silicon negative electrode material, porous carbon is used as a template, nano silicon is loaded inside or on the surface of the pore of the porous carbon, a 3D interpenetrating structure is formed, conductive carbon and ion conductor material coating is formed on the surfaces of the porous carbon and the nano silicon, optimization such as opening and closing, pore diameter and porosity is integrated, and a buffer space is provided for volume expansion of a silicon material in the charging and discharging process.
In some embodiments, the present application provides a low expansion silicon anode material comprising porous carbon/graphite, nanosilicon, conductive carbon, and an ionic conductor material, the pores of the porous carbon/graphite comprising open and closed pores; the proportion of the open pores is 80-99.9% based on the total amount of the open pores and the closed pores being 100%.
The method has the beneficial effects that the porous carbon is taken as the template, the nano silicon is loaded in the pores or on the surfaces of the pores, the porous carbon provides a continuous conductive sub-channel, and the nano silicon material ensures the high capacity density of the cathode material; the optimization of open pores, closed pores, pore diameters, porosity and the like of the porous carbon is integrated, so that the volume expansion of the silicon material can be greatly buffered. In addition, the outer surface of the porous carbon is further coated with a conductive carbon and ion conductor material layer in a double-layer coating mode, so that on one hand, the electronic conductivity and the ionic conductivity can be improved, on the other hand, the electrolyte can be prevented from being in direct contact with active substances, and therefore the electrochemical performance of the material is improved.
Additional aspects and advantages of embodiments of the present application will be described and shown in the following description, or will be apparent from the description, or may be learned by practice of embodiments of the present application.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of the present application;
FIG. 2 is a schematic structural diagram of another embodiment of the present application;
FIG. 3 is a schematic structural diagram of an embodiment of the present application;
fig. 4 is a schematic structural diagram of another embodiment of the present application.
Detailed Description
Embodiments of the present application will be described in detail below. The embodiments of the present application should not be construed as limiting the present application.
In the present application, amounts, ratios, and other numerical values are presented in a range format, with the understanding that such range format is used for convenience and brevity, and will be understood flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
In the claims and the detailed description, a list of items linked by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" means a only; only B; or A and B. Item a may comprise a single element or multiple elements and item B may comprise a single element or multiple elements.
In this application, Dv50 is the particle size corresponding to 50% of the cumulative volume percent of the material.
The embodiment provides a low-expansion silicon negative electrode material, which comprises porous carbon, nano silicon, conductive carbon and an ion conductor material, wherein holes of the porous carbon comprise open holes and closed holes, the open holes are used for accommodating the nano silicon material, and the closed holes can be used for buffering the volume expansion of the silicon; the ratio of the number of the open pores to the number of the closed pores is 80-99.9%, preferably 85-95%, based on 100% of the total number of the open pores and the closed pores, and if the number of the open pores is too small, the amount of the nano silicon material which can be accommodated is too small, which affects the capacity density of the material.
In some embodiments, the pore diameter of the open pore is 50 to 1000nm, wherein 50 to 80% by volume of the total volume of the open pore is 200 to 1000nm, preferably 50 to 70% by volume of the total volume of the open pore is 300 to 600nm, if the volume is less than 50%, the embedded nano silicon content is low, the specific material capacity is low, and if the volume is more than 80%, the embedded nano silicon content is high, the volume expansion is large, and the structural collapse is easy to occur; the aperture of the opening is larger than 200nm, so that the nano silicon material can be embedded, and a certain pore can be remained for buffering the volume expansion of the silicon material; if the pore diameter of the open pore is larger than 1000nm, the porous carbon structure is unstable and easy to collapse.
In some embodiments, the porous carbon has a porosity of 2 to 95%, preferably 10 to 80%, and too low a porosity may affect the intercalation of the nano-silicon material, thereby affecting the material capacity; too high porosity can affect the conductivity and structural strength of the material.
Specifically, the porous carbon can be prepared by: by means of SiO 2 The porous carbon is obtained by removing the template after pyrolysis by taking phenolic resin, furfuryl alcohol, asphalt, sucrose, benzene, divinylbenzene, polyacrylonitrile and ethylene as carbon sources, controlling the proportion of open and closed pores through reaction pressure, solid content and the like, and controlling porosity and aperture through the proportion and particle size of the template.
In some embodiments, the nano-silicon coats at least a portion of the pore walls of the open pores and at least a portion of the surface of the porous carbon; the conductive carbon coats at least a portion of the surface of the silicon particles; the ionic conductor material coats at least a portion of the conductive carbon.
Fig. 1 is a schematic structural diagram of an embodiment, the porous carbon 1 contains closed pores 2 and open pores 3, the nano-silicon 4 is coated on the pore walls of the open pores 3 and the surface of the porous carbon 1, the conductive carbon 5 is coated on the surface of the nano-silicon 4, and the ionic conductor material 6 is coated on the surface of the conductive carbon 5. The porous carbon 1 provides a continuous conductive channel, the closed hole 2 can buffer partial volume expansion, and the open hole 3 reserves partial pores for further relieving the volume expansion, so that the low expansion rate of the material is ensured; the nano silicon 4 ensures high specific capacity of the material, the conductive carbon 5 further improves the electronic conductivity of the material, and the ion conductor 6 provides more ion conduction channels, and simultaneously isolates the electrolyte to prevent side reaction.
Fig. 2 is a schematic structural diagram of another embodiment, the porous carbon 1 contains closed pores 2 and open pores 3, the nano-silicon 4 is coated on the pore walls of the open pores 3 and the surface of the porous carbon 1, the conductive carbon 5 is coated on the surface of the nano-silicon 4 and is gathered at the pore openings of the open pores 3 to complete pore sealing, and the ionic conductor material 6 is coated on the surface of the conductive carbon 5 to finally form the spheroidal silicon-containing particles.
In some embodiments, the nano-silicon is filled in the open pores; the conductive carbon coats at least part of the surface of the porous carbon; the ionic conductor material coats at least a portion of the conductive carbon.
In some embodiments, at least a portion of the surface of the nano-silicon is coated with conductive carbon for improving the conductivity of the nano-silicon; the nano-silicon also comprises a fibrous carbon material for binding the nano-silicon material and playing a role of elastic pinning, wherein the fibrous carbon material comprises at least one of CNT, carbon fiber, vapor-grown carbon fiber and branched carbon (such as Ketjen black).
Fig. 3 is a schematic structural diagram of an embodiment, the porous carbon 1 contains closed pores 2 and open pores 3, and the nano silicon 4 is in a particle form, is filled in the pores of the open pores 3, and forms a 3D network interpenetrating structure with the porous carbon 1, so that structural stability is ensured; in order to improve the conductivity of the nano silicon, the surface of the nano silicon 4 is also coated with conductive carbon 7, and fibrous carbon materials 8 are also contained among nano silicon 4 particles and used for binding the nano silicon 4 particles, so that the elastic pinning effect is realized, and the structural stability is ensured; the conductive carbon 7 is coated on the surface of the porous carbon 5 and the surface of the nano silicon 4, and the ionic conductor material 6 is coated on the surface of the conductive carbon 5.
Fig. 4 is a schematic structural diagram of another embodiment, the porous carbon 1 contains closed pores 2 and open pores 3, and the nano-silicon 4 is in the form of particles and is filled in the pores of the open pores 3; the surface of the nano silicon 4 is also coated with conductive carbon 7, and fibrous carbon materials 8 are also contained among nano silicon 4 particles; the conductive carbon 7 is coated on the surface of the porous carbon 5 and the surface of the nano silicon 4, and is gathered at the orifice of the opening 3 to complete hole sealing, and the ionic conductor material 6 is coated on the surface of the conductive carbon 5, so that the sphere-like silicon-containing particles are finally formed.
In some embodiments, the mass ratio of the porous carbon is 5-97.2% based on 100% of the mass of the silicon anode material; the mass ratio of the silicon particles is 2-80%; the mass proportion of the conductive carbon is 0.5-20%; the mass percentage of the ionic conductor material is 0.3-10%.
In some embodiments, the Dv50 particle size of the nano silicon is 1-50 nm, and if the Dv50 particle size of the nano silicon material is too small, the specific surface area of the material is too large, which may cause severe side reactions; if the particle size is too large, the nano silicon material is not easily embedded into the pores of the porous carbon.
In some embodiments, the nano-silicon comprises elemental silicon (nano-silicon particles), silicon oxide SiO x (0 < x < 2), a silicon alloy (Si-M, such as Si-Sn); the conductive carbon comprises at least one of hard carbon, soft carbon, carbon black, graphite, carbon fiber, vapor-grown carbon fiber, carbon nanotube and graphene; the ion conductor material includes at least one of alumina, titania, zirconia, vanadia, zinc oxide, cobalt oxide, phosphorus oxide, boron oxide, aluminum metaphosphate, lithium metaaluminate, cobalt metaphosphate, lithium phosphate, lithium aluminate, lithium fluoride, aluminum fluoride, iron fluoride, aluminum hydroxide, LISICON-type solid electrolyte, NASICION-type solid electrolyte, perovskite-type solid electrolyte, garnet-type solid electrolyte, sulfide solid electrolyte, PEO-based polymer electrolyte.
Examples
Example 1
Dispersing nano silicon dioxide in phenolic resin, adjusting to a certain solid content, vacuumizing by using a pressure kettle until the pressure is less than or equal to-0.095 MPa, continuously introducing nitrogen to pressurize to 1MPa to adjust micropores of the phenolic resin after 30min, slowly heating to 160 ℃ at a speed of 0.5 ℃/min after pressurization is finished, preserving heat for 5h to finish resin curing, continuously relieving pressure in the heating process, and maintaining the pressure to be stable. Heating and carbonizing the cured resin in a resistance furnace, wherein the heating rate is 1 ℃/min, and the carbonization temperature is 1000 ℃; after resin carbonization, crushing by using an airflow mill, and controlling Dv50=10 um; and after the powder is crushed, etching in a static bed, removing the nano silicon dioxide by using HF as an etching agent, washing with deionized water after the nano silicon dioxide is removed, and drying to finish the preparation of the porous carbon.
Heating porous carbon in a rotary furnace to 500 ℃, introducing silane with 3% volume concentration, introducing hydrogen serving as diluent gas, introducing the gas by adopting a pulse method, controlling the pressure to be 0-0.05 MPa, and reacting for 240min so as to deposit nano silicon on the surface of porous carbon pores in order to enable the gas to enter the porous carbon pores and improve the gas utilization rate; then, heating to 700-850 ℃, introducing acetylene with the volume concentration of 5-30%, wherein the diluent gas is argon, the reaction time is 1-4 h, and coating a layer of conductive carbon on the surface of the nano silicon; and then, raising the temperature to 850-1100 ℃, introducing acetylene with the volume concentration of 5-30%, wherein the diluent gas is argon, reacting for 1-4 h, and generating conductive carbon at the opening and the outer surface to complete hole sealing. The permeable coating and the surface coating can be controlled by adjusting the reaction temperature, the low-temperature reaction rate is low, the gas can permeate into the pores, the high-temperature reaction rate is high, and the gas reacts on the surface to complete hole sealing and coating.
And dispersing the conductive carbon-coated powder and lithium metaphosphate in a PAA-Li solution, uniformly mixing to prepare slurry, wherein the solid content of the slurry is 35%, drying the powder by using a spray dryer, and dispersing and bonding the aluminum metaphosphate on the surface of porous carbon to prepare the silicon cathode material.
Example 2
Porous carbon was prepared by the same method as in example 1.
Grinding the silicon powder in an ethanol solvent until D50 is below 50nm to prepare nano silicon slurry, adding the carbon nano tube, and continuing grinding and dispersing to prepare nano mixed slurry of nano silicon and the carbon nano tube; dispersing porous carbon in nano mixed slurry of nano silicon and carbon nano tubes, adding a solvent for dilution, and controlling the solid content to be 22%; and (3) impregnating the slurry in a pressure kettle in vacuum and pressure to ensure that most of the nano mixed slurry enters pores of the porous carbon: vacuumizing until the pressure is less than or equal to-0.095 MPa, continuously introducing nitrogen to pressurize to 4MPa after 30min, maintaining the pressure for 2h, and releasing the pressure to complete impregnation so as to fill nano silicon in porous carbon pores; carrying out solid-liquid separation on the slurry subjected to vacuum and pressure impregnation by adopting a centrifugal machine, and removing the nano slurry which does not enter pores; the filter cake was air dried using an air dryer. And heating the dried powder in a rotary furnace to 950 ℃, introducing acetylene with the volume concentration of 10%, wherein the diluent gas is argon, reacting for 90min, and coating a layer of conductive carbon on the surfaces of the nano-silicon and the porous carbon. Dispersing the conductive carbon coated powder and the alumina sol in water, uniformly mixing to prepare slurry, wherein the solid content of the slurry is 35%, and preparing the slurry into powder by adopting a spray dryer; and finally, sintering the powder coated with the aluminum hydroxide on the surface in a rotary furnace at the sintering temperature of 700 ℃ for 2h, converting the aluminum hydroxide into aluminum oxide, and preparing the silicon cathode material after sintering.
Examples 3 to 4
Other steps are the same as the process parameters of the embodiment 1, and the difference is that the proportion of the number of open pores and the proportion of the volume of the open pores in the range of 200-1000 nm are different, the number of open pores and the pore diameter can be adjusted by adjusting the particle size of the silicon dioxide Dv50, the weight ratio of the silicon dioxide and the phenolic resin, the reaction pressure and the solid content, but the proportion of the number of open pores and the proportion of the volume of the open pores in the range of 200-1000 nm are still within the scope required by the application.
Comparative examples 1 to 4
Other steps are the same as the process parameters of the embodiment 1, except that the proportion of the number of open pores and the proportion of the open pores with the diameter of 200-1000 nm are different, and the number of open pores and the diameter of the open pores can be adjusted by adjusting the particle size of the silicon dioxide D50, the weight ratio of the silicon dioxide and the phenolic resin, the reaction pressure and the solid content, so that the proportion of the number of open pores and the proportion of the open pores with the diameter of 200-1000 nm are out of the range required by the application.
The silicon negative electrode materials prepared in the examples were evaluated for their performance by the following methods.
Open and closed pore number test: and (3) preparing a sample by using low-carbon-residue resin as embedding resin, polishing, completely ablating the embedding resin under an inert protective atmosphere to obtain a test sample, and counting the data of open pores and closed pores through a metallographic microscope system.
The porosity, pore diameter and ratio test method comprises the following steps: mercury intrusion detectors or BET specific surface area testers are used.
The method for testing the particle size of the nano silicon particles comprises the following steps: and (3) observing the nano silicon particles through a field emission scanning electron microscope or a transmission electron microscope, directly measuring the particle diameters of 5-10 nano silicon particles through a scale, and taking the average value of the particle diameters as the final particle diameter of the nano silicon particles.
The negative electrode materials obtained in the examples were assembled into button half cells according to a conventional method, and the electrochemical properties thereof were tested: according to the mass ratio of 80: 9: 1: 10 the prepared anode material powder: SP (carbon black): CNT (carbon nanotube): PAA (polyacrylic acid) is mixed, a proper amount of deionized water is added as a solvent, and the mixture is continuously stirred for 8 hours to be pasty by a magnetic stirrer. And pouring the stirred slurry on a copper foil with the thickness of 9 mu m, coating the slurry by using an experimental coater, and drying the coated slurry for 6 hours at the temperature of 85 ℃ under the vacuum (-0.1 MPa) condition to obtain the negative electrode plate. Rolling the electrode plate to 100 μm on a manual double-roller machine, making into a wafer with diameter of 12mm with a sheet punching machine, drying at 85 deg.C under vacuum (-0.1 MPa) for 8 hr, weighing, and calculating the weight of active substance. A metal lithium sheet is used as a counter electrode, a polypropylene microporous membrane is used as a diaphragm, 1mol/L LiPF6 in EC: DEC =1:1 Vol% with 5.0% FEC is used as electrolyte, and a CR2032 type button cell is assembled in a glove box.
Initial specific capacity: carrying out charging and discharging tests on the battery by using a blue electricity (LAND) battery test system, standing for 6 hours, discharging to 0.005V at 0.05C, and then discharging to 0.005V at 0.01C; standing for 5min, and charging to 1.5V at constant current of 0.05C; the specific charge capacity obtained at this time and the initial specific capacity of the material.
And (3) testing the full-electric expansion rate for the first time: the CR2032 button cell is prepared by the method, the charging and discharging test is carried out on the cell by a blue electricity (LAND) cell test system, the cell is discharged to 0.005V at 0.05C after standing for 6h, then discharged to 0.005V at 0.01C, the button cell is disassembled in a glove box, and then the thickness of the pole piece is measured. The expansion ratio is calculated in the following manner: (pole piece thickness after circulation-fresh pole piece thickness)/fresh pole piece thickness x 100%.
And (3) testing the cycle performance: carrying out charging and discharging tests on the battery by using a blue electricity (LAND) battery test system, standing for 6 hours, discharging to 0.005V at 0.05C, and then discharging to 0.005V at 0.01C; standing for 5min, and charging to 1.5V at constant current of 0.05C; standing for 5min, and repeating the steps twice; then discharging to 0.005V by adopting 0.25C; and standing for 5min, charging the battery to 1.5V at a constant current of 0.25C, circulating for 20 times, testing the cycle performance of the battery, and calculating the charge capacity of the 20 th circle/the charge capacity of the 1 st circle multiplied by 100% to obtain the capacity retention rate.
And (3) rate performance test: and standing the prepared button cell at room temperature for 12 hours, performing constant-current charge and discharge test on a blue-ray test system, wherein the charge and discharge cutoff voltage is 3.0-4.25V, and charging and discharging are performed at 0.1C for 3 times in a circulating manner. And then the charge and discharge are carried out by 0.5C current, and the cycle is carried out for 3 times. Finally, the specific capacity measured under 0.5C/the specific capacity of 0.1C multiplied by 100 percent is used for obtaining the ratio, and the higher the ratio is, the better the multiplying power performance is.
TABLE 2 comparison of the performances of the anode materials obtained in the examples
Sample (I) Proportion of open pores The ratio of the pore diameter of the opening is 200-1000 nm First full electric expansion rate Capacity retention rate 0.5C specific capacity/0.1C specific capacity
Example 1 80% 50% 55% 90% 85%
Example 2 80% 50% 55% 89% 86%
Example 3 85% 75% 63% 85% 90%
Example 4 99.9% 80% 70% 85% 90%
Comparative example 1 50% 80% 55% 75% 80%
Comparative example 2 100% 50% 77% 80% 85%
Comparative example 3 80% 20% 60% 75% 80%
Comparative example 4 99.9% 90% 80% 70% 75%
The test results of the silicon negative electrode materials prepared in the respective examples and comparative examples are shown in table 1, and example 1 is different from example 2 in that: in example 1, nano silicon is loaded on the wall of the pore, and in example 2, the nano silicon is filled in the pore of the pore, and from the test results of example 1 and example 2, the performances of the anode materials with the nano silicon existing at different positions are similar. The data of the embodiment 1 and the embodiments 3-4 show that the negative electrode material with the best electrical property can be obtained by optimizing the opening number ratio and the pore size and the ratio. From the data of each example and comparative example, the silicon anode material provided by the application has low expansion rate and good capacity retention rate and rate performance. As can be seen from the comparative example 2 data, the presence of an appropriate amount of closed cells helps to relieve volume expansion.
Variations and modifications to the above-described embodiments may occur to those skilled in the art based upon the disclosure and teachings of the above specification. Therefore, the above description is not intended to limit the invention, the invention is not limited to the specific embodiments disclosed and described above, and modifications and variations such as equivalent substitutions of each raw material and addition of auxiliary components, selection of specific modes, etc., made by those skilled in the art within the substantial scope of the embodiments, should also fall within the protection scope of the claims of the present invention.

Claims (9)

1. A low-expansion silicon negative electrode material comprises porous carbon, nano-silicon, conductive carbon and an ion conductor material, and is characterized in that pores of the porous carbon comprise open pores and closed pores; the open cell number accounts for 80-99.9% of the total number of the open cells and the closed cells being 100%.
2. The silicon negative electrode material according to claim 1, wherein the pore diameter of the pores is 50 to 1000nm, and 50 to 80% by volume of the pores is 200 to 1000nm, based on 100% by volume of the total pore volume.
3. The silicon anode material according to claim 1, wherein the porosity of the porous carbon is 2 to 95%.
4. The silicon anode material of claim 2, wherein the nano-silicon coats at least a portion of the pore walls of the open pores and at least a portion of the surface of the porous carbon; the conductive carbon coats at least one part of the surface of the nano silicon; the ionic conductor material coats at least a portion of the conductive carbon.
5. The silicon negative electrode material of claim 2, wherein the nano-silicon is filled in the open pores; the conductive carbon coats at least a portion of the surface of the porous carbon; the ionic conductor material coats at least a portion of the conductive carbon.
6. The silicon anode material of claim 5, wherein at least a portion of the surface of the nano-silicon is coated with conductive carbon; the nano-silicon further contains a fibrous carbon material, and the fibrous carbon material includes at least one of CNT, carbon fiber, vapor-grown carbon fiber, and branched carbon.
7. The silicon negative electrode material according to claim 1, wherein the mass proportion of the porous carbon is 5 to 97.2% based on 100% of the mass of the silicon negative electrode material; the mass ratio of the silicon particles is 2-80%; the mass proportion of the conductive carbon is 0.5-20%; the mass percentage of the ionic conductor material is 0.3-10%.
8. The silicon negative electrode material of claim 1, wherein the Dv50 particle size of the nano silicon is 1 to 50 nm.
9. The silicon anode material of claim 1, wherein the nano-silicon comprises elemental silicon, silicon oxide SiO x (0 < x < 2), and a silicon alloy; the conductive carbon comprises at least one of hard carbon, soft carbon, carbon black, graphite, carbon fiber, vapor-grown carbon fiber, carbon nanotube and graphene; the ion conductor material includes at least one of alumina, titania, zirconia, vanadia, zinc oxide, cobalt oxide, phosphorus oxide, boron oxide, aluminum metaphosphate, lithium metaaluminate, cobalt metaphosphate, lithium phosphate, lithium aluminate, lithium fluoride, aluminum fluoride, iron fluoride, aluminum hydroxide, LISICON-type solid electrolyte, NASICION-type solid electrolyte, perovskite-type solid electrolyte, garnet-type solid electrolyte, sulfide solid electrolyte, PEO-based polymer electrolyte.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115020689A (en) * 2022-08-08 2022-09-06 溧阳天目先导电池材料科技有限公司 Nano silicon-carbon composite material for secondary lithium battery and preparation method and application thereof
CN116314729A (en) * 2023-05-22 2023-06-23 厦门海辰储能科技股份有限公司 Negative electrode particles, preparation method thereof, negative electrode plate and energy storage device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115020689A (en) * 2022-08-08 2022-09-06 溧阳天目先导电池材料科技有限公司 Nano silicon-carbon composite material for secondary lithium battery and preparation method and application thereof
CN116314729A (en) * 2023-05-22 2023-06-23 厦门海辰储能科技股份有限公司 Negative electrode particles, preparation method thereof, negative electrode plate and energy storage device
CN116314729B (en) * 2023-05-22 2023-07-21 厦门海辰储能科技股份有限公司 Negative electrode particles, preparation method thereof, negative electrode plate and energy storage device

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