A lithium-ion battery anode material and preparation method

Abstract

An embodiment of the present invention provides a lithium-ion battery anode material and a preparation method. The lithium-ion battery anode material includes a base material and a surface modification material. The base material is spherical graphite, and the surface modification material is silver nanoparticles. The lithium-ion battery anode material is a graphite-silver nanoparticle mixture obtained by surface-modifying spherical graphite with silver nanoparticles. The silver nanoparticles in the graphite-silver nanoparticle mixture are present in a single substance on the surface of the spherical graphite. The present invention modifies the surface of the spherical graphite with silver nanoparticles to form a hybrid anode with dual mechanisms of lithium ion insertion / deinsertion and metal lithium plating / stripping. This method can effectively control the lithium metal deposition site, selectively deposit lithium metal to inhibit the formation of lithium dendrites, and inhibit the formation of "dead lithium" caused by continuous consumption of electrolyte, thereby improving the coulombic efficiency and theoretical gram capacity of the graphite anode, and further improving the energy density of the lithium battery system.

Description

Technical Field

[0001] The present invention relates to the field of lithium ion batteries, and in particular to a lithium ion battery anode material and a preparation method thereof. Background Art

[0002] In recent years, with the growing demand for energy storage, the research and development of high-energy-density batteries has become particularly important. In order to improve the energy density of lithium-ion batteries, many researchers have been committed to developing new high-voltage or high-capacity electrode materials. Since the launch of the first commercial lithium-ion battery in 1991, graphite anode materials have dominated the market.

[0003] However, the theoretical capacity of graphite anode is only 372 mAh g -1 (milliampere-hours per gram), which is difficult to meet the demand for high energy density; lithium metal has the highest theoretical capacity (3860mAh g -1 ) and the lowest electrochemical potential (-3.04 V vs SHE, where V vs SHE means volts relative to the standard hydrogen electrode), it is considered to be an ideal material to replace the traditional graphite anode; however, lithium metal as an anode has the problem of lithium dendrites, which will lead to a decrease in the cycle reversibility of the battery, thus seriously limiting the practical application of lithium metal anodes. Summary of the Invention

[0004] In view of the above problems, a lithium ion battery anode material and a preparation method are proposed to overcome the above problems or at least partially solve the above problems, including:

[0005] A lithium-ion battery anode material, comprising a base material and a surface modification material, wherein the surface modification material is used to perform surface modification on the base material;

[0006] The base material is spherical graphite, the surface modification material is silver nanoparticles, the lithium-ion battery anode material is a graphite-silver nanoparticle mixture obtained by surface-modifying the spherical graphite with the silver nanoparticles, and the silver nanoparticles in the graphite-silver nanoparticle mixture exist in a single substance on the surface of the spherical graphite.

[0007] Optionally, the lithium-ion battery anode material is characterized in that the particle size of the spherical graphite is any one of 14 μm, 16 μm, 23 μm and 25 μm.

[0008] Optionally, the lithium-ion battery anode material is characterized in that the spherical graphite is etched spherical graphite.

[0009] Optionally, the etching atmosphere of the etching process is any one of an air atmosphere and a carbon dioxide atmosphere.

[0010] Optionally, the graphite-silver nanoparticle mixture is obtained by immersing the spherical graphite in a silver salt solution and performing heat treatment; the silver salt solution is any one of a silver nitrate solution and a silver acetate solution.

[0011] A method for preparing a lithium-ion battery anode material, the method comprising:

[0012] Etching the spherical graphite to obtain oxidized spherical graphite;

[0013] stirring the oxidized spherical graphite and the silver salt solution at room temperature to obtain a graphite-silver salt solution;

[0014] placing the graphite-silver salt solution in a drying oven for drying to obtain a graphite-silver salt solid mixture;

[0015] placing the graphite-silver salt solid mixture in a tube furnace for burning while protecting it with argon gas to obtain a graphite-silver nanoparticle mixture;

[0016] adding the graphite-silver nanoparticle mixture into ethanol and placing it in a centrifuge for washing;

[0017] The cleaned graphite-silver nanoparticle mixture is placed in an oven for drying to obtain the lithium-ion battery anode material.

[0018] Optionally, the particle size of the spherical graphite is any one of 14 μm, 16 μm, 23 μm and 25 μm; and the etching atmosphere of the etching process is any one of air atmosphere and carbon dioxide atmosphere.

[0019] Optionally, the silver salt solution is any one of a silver nitrate solution and a silver acetate solution; the concentration of the silver salt solution is 0.1 mol / L to 0.3 mol / L.

[0020] Optionally, the graphite-silver salt solid mixture is placed in a tube furnace for calcination at a temperature ranging from 400° C. to 600° C. and for a calcination time of 2 hours.

[0021] Optionally, the etching time of the etching process ranges from 30 minutes to 50 minutes.

[0022] The embodiments of the present invention have the following advantages:

[0023] In an embodiment of the present invention, a lithium-ion battery anode material is provided, which includes a base material and a surface modification material, wherein the surface modification material is used to modify the surface of the base material; wherein the base material is spherical graphite, the surface modification material is silver nanoparticles, and the lithium-ion battery anode material is a graphite-silver nanoparticle mixture obtained by surface-modifying the spherical graphite with silver nanoparticles, wherein the silver nanoparticles in the graphite-silver nanoparticle mixture exist in a single substance on the surface of the spherical graphite; the present invention modifies the surface of the spherical graphite with silver nanoparticles to form a hybrid anode with dual mechanisms of lithium ion insertion / deinsertion and metal lithium plating / stripping, thereby effectively controlling the lithium metal deposition site, enabling selective lithium metal deposition to inhibit the formation of lithium dendrites, and inhibiting the formation of "dead lithium" caused by continuous consumption of electrolyte, thereby improving the coulombic efficiency and theoretical gram capacity of the graphite anode, and thus improving the energy density of the lithium battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the description of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a flow chart of the steps of a method for preparing a lithium-ion battery anode material provided by one embodiment of the present invention;

[0026] Figure 2 This is a flow chart of the steps of a method for preparing another lithium-ion battery anode material provided by one embodiment of the present invention;

[0027] Figure 3 This is a flow chart of the steps of a method for preparing another lithium-ion battery anode material provided by one embodiment of the present invention;

[0028] Figure 4 is an XRD spectrum of a mixed anode, spherical graphite, and silver provided in one embodiment of the present invention;

[0029] Figure 5 1 is a graph showing voltage variation of a graphite anode and a mixed anode at a current density of 0.2C provided by one embodiment of the present invention;

[0030] Figure 6 This is a discharge to 370mAh g provided by an embodiment of the present invention. -1 SEM image of the mixed anode;

[0031] Figure 7 This is a discharge to 500mAh g provided by an embodiment of the present invention.-1 SEM image of the mixed anode;

[0032] Figure 8 This is a graph showing the cycling performance test results of a hybrid anode half-cell provided by one embodiment of the present invention at a current density of 0.2C. DETAILED DESCRIPTION

[0033] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0034] In related technologies, the theoretical capacity of graphite anode is only 372 mAh g -1 , which makes it difficult to meet the demand for high energy density; lithium metal has the highest theoretical capacity and the lowest electrochemical potential, and is considered to be an ideal material to replace traditional graphite anodes; however, lithium metal as an anode has the problem of lithium dendrites, which will lead to a decrease in the cycle reversibility of the battery, and thus seriously limit the practical application of lithium metal anodes.

[0035] In the embodiment of the present invention, based on the core technical concept of surface modification of spherical graphite by silver nanoparticles, the lithium-ion battery anode material in the related art is improved, and a lithium-ion battery anode material is proposed, the lithium-ion battery anode material comprising a base material and a surface modification material, the surface modification material being used to modify the surface of the base material;

[0036] The base material is spherical graphite, the surface modification material is silver nanoparticles, the lithium-ion battery anode material is a graphite-silver nanoparticle mixture obtained by surface-modifying the spherical graphite with the silver nanoparticles, and the silver nanoparticles in the graphite-silver nanoparticle mixture exist in a single substance on the surface of the spherical graphite.

[0037] The anode material of lithium-ion batteries is a key component of the battery energy storage system. Its main function is to provide a place for lithium ions to be embedded during the battery charging process and to release lithium ions during the discharge process to power the battery. The choice of anode material has a great impact on the battery's energy density, cycle life, charging rate and safety.

[0038] In a specific implementation, a lithium-ion battery anode material can be synthesized by surface-modifying a base material with a surface-modifying material. Specifically, the base material can be spherical graphite, and the surface-modifying material can be silver nanoparticles. The lithium-ion battery anode material can be a graphite-silver nanoparticle mixture obtained by surface-modifying the spherical graphite with the silver nanoparticles. The silver nanoparticles in the graphite-silver nanoparticle mixture can exist in the surface of the spherical graphite in a simple form. The present invention can form a hybrid anode with a dual mechanism of lithium ion insertion / deinsertion and metal lithium plating / stripping by modifying the surface of the spherical graphite with silver nanoparticles. When the voltage is above 0V, only Li+ occurs. + Intercalation phenomenon occurs, and when the voltage drops below 0V, metallic lithium will begin to nucleate. Since silver nanoparticles exhibit zero overpotential during the lithium metal deposition process, they can effectively control the lithium metal deposition site, selectively deposit lithium metal, inhibit the formation of lithium dendrites, and inhibit the continuous consumption of electrolyte leading to the formation of "dead lithium", thereby improving the coulombic efficiency and theoretical gram capacity of the graphite anode, and then improving the energy density of the lithium battery system.

[0039] In the above content, the lithium ion insertion / deinsertion mechanism refers to the fact that when the battery is charging, lithium ions migrate from the cathode to the anode and are embedded in the anode material; conversely, during the discharge process, the lithium ions embedded in the anode material migrate back to the cathode again for use by the battery; the efficiency and speed of this process determine the battery's charge and discharge performance.

[0040] Traditional lithium battery materials may encounter problems such as material structure destruction and decreased conductivity during long-term charge and discharge cycles. The present invention effectively increases the electron conduction pathway and lithium ion diffusion channel through the introduction of silver nanoparticles, accelerates the insertion and deintercalation speed of lithium ions, reduces energy loss during battery charge and discharge, and significantly improves the battery's cycle performance and charge and discharge efficiency.

[0041] Furthermore, the metal lithium plating / stripping mechanism refers to the phenomenon that metallic lithium begins to form in the battery when the voltage drops to a very low level; this situation usually occurs during high-rate discharge or when the battery power is very low; in the present invention, the addition of silver nanoparticles helps to control the deposition of metallic lithium, making it more uniform and reducing the risk of lithium dendrite formation.

[0042] Regarding zero overpotential, overpotential refers to the difference between the actual potential and the equilibrium potential in an electrochemical reaction; zero overpotential means the reaction is highly efficient, with virtually no energy loss. In this invention, silver nanoparticles promote efficient lithium-ion conversion, reduce energy loss, and improve the battery's charge and discharge efficiency.

[0043] Furthermore, lithium dendrites are a phenomenon that may occur during the use of the battery, and are more likely to form under high-rate charge and discharge and low-temperature conditions. The formation of lithium dendrites can pierce the diaphragm, leading to short circuits and even thermal runaway. The application of silver nanoparticles in the present invention can effectively inhibit the formation of lithium dendrites, improve the safety of the battery, and inhibit the formation of "dead lithium" caused by the continuous consumption of electrolyte, thereby improving the coulombic efficiency and theoretical gram capacity of the graphite anode, and thus improving the energy density of the lithium battery system. Energy density is one of the key indicators for evaluating battery performance. It indicates how much energy can be stored per unit weight or volume of the battery; by increasing the gram capacity of the anode material, that is, more electricity can be stored per gram of material, the energy density of the battery can be significantly improved.

[0044] In one embodiment of the present invention, the particle size of the spherical graphite is any one of 14 μm, 16 μm, 23 μm and 25 μm.

[0045] In practical applications, the particle size of spherical graphite can be determined from 14μm, 16μm, 23μm, and 25μm. During the charge and discharge process, the insertion and deintercalation of lithium ions causes the volume of the anode material to expand and contract. The appropriate particle size helps balance the structural stability and electrochemical performance of the battery, reduces cracks or damage caused by volume changes, and improves the cycle stability of the battery.

[0046] In one embodiment of the present invention, the spherical graphite is etched spherical graphite.

[0047] In practice, spherical graphite can be etched, which changes its surface properties, creating micropores or grooves on its surface and increasing the material's specific surface area. A higher specific surface area means more active sites for lithium ion insertion and extraction, thereby improving the battery's electrochemical performance.

[0048] In one embodiment of the present invention, the etching atmosphere of the etching process is any one of an air atmosphere and a carbon dioxide atmosphere.

[0049] In practical applications, etching can be performed in an air atmosphere or a carbon dioxide atmosphere, and the corresponding etching atmosphere can be selected according to actual application requirements.

[0050] In one embodiment of the present invention, the graphite-silver nanoparticle mixture is obtained by immersing the spherical graphite in a silver salt solution and performing heat treatment; the silver salt solution is any one of a silver nitrate solution and a silver acetate solution.

[0051] In a specific implementation, the spherical graphite can be immersed in a silver salt solution and subjected to heat treatment to obtain a graphite-silver nanoparticle mixture, and the silver salt solution can be selected from a silver nitrate solution and a silver acetate solution.

[0052] Reference Figure 1 , shows a flow chart of the steps of a method for preparing a lithium-ion battery anode material provided by one embodiment of the present invention, which may specifically include the following steps:

[0053] Step 101, etching the spherical graphite to obtain oxidized spherical graphite;

[0054] In practical applications, spherical graphite can be used as a base material for lithium-ion battery anode materials, and the spherical graphite can be etched in an air atmosphere or a carbon dioxide atmosphere for 30 to 50 minutes, wherein the etching temperature can be 650° C.; thereby obtaining oxidized spherical graphite.

[0055] In one embodiment of the present invention, the particle size of the spherical graphite is any one of 14 μm, 16 μm, 23 μm and 25 μm; and the etching atmosphere of the etching process is any one of air atmosphere and carbon dioxide atmosphere.

[0056] In practice, the spherical graphite particle size can be selected from 14μm, 16μm, 23μm, and 25μm. During the charge and discharge process, the insertion and deintercalation of lithium ions causes the volume of the anode material to expand and contract. An appropriately sized particle size helps balance the battery's structural stability and electrochemical performance, reducing cracks or damage caused by volume changes and improving the battery's cycling stability. Furthermore, etching can be performed in either air or carbon dioxide atmospheres, with the appropriate etching atmosphere selected based on actual application requirements.

[0057] In one embodiment of the present invention, the etching time of the etching process ranges from 30 minutes to 50 minutes.

[0058] In practical applications, the etching time range of the etching process can be set to 30 minutes to 50 minutes, so as to ensure that the etching process can achieve the desired effect.

[0059] Step 102, stirring the oxidized spherical graphite and a silver salt solution at room temperature to obtain a graphite-silver salt solution;

[0060] In a specific implementation, the oxidized spherical graphite obtained in the above step can be stirred with the silver salt solution at room temperature for 2 hours to obtain a graphite-silver salt solution; the specific stirring time can be appropriately adjusted according to actual needs.

[0061] In one embodiment of the present invention, the silver salt solution is any one of a silver nitrate solution and a silver acetate solution; and the concentration of the silver salt solution is 0.1 mol / L to 0.3 mol / L.

[0062] In practical applications, the silver salt solution can be selected from silver nitrate solution and silver acetate solution; and the concentration of the silver salt solution can range from 0.1 mol / L to 0.3 mol / L to ensure the surface modification effect.

[0063] Step 103, placing the graphite-silver salt solution in a drying oven for drying to obtain a graphite-silver salt solid mixture;

[0064] In a specific implementation, the graphite-silver salt solution can be placed in a drying oven at 100° C. for drying to obtain a graphite-silver salt solid mixture.

[0065] Step 104, placing the graphite-silver salt solid mixture in a tube furnace for calcination while protecting it with argon gas to obtain a graphite-silver nanoparticle mixture;

[0066] In practical applications, the graphite-silver salt solid mixture can be placed in a tube furnace and burned for 2 hours under argon protection to obtain a graphite-silver nanoparticle mixture.

[0067] In one embodiment of the present invention, the graphite-silver salt solid mixture is placed in a tube furnace for calcination at a temperature ranging from 400° C. to 600° C. and for a calcination time of 2 hours.

[0068] In a specific implementation, the burning temperature range can be set to 400° C. to 600° C. and the burning time can be set to 2 hours to ensure sufficient burning and thus achieve the ideal surface modification effect.

[0069] Step 105, adding the graphite-silver nanoparticle mixture to ethanol and placing it in a centrifuge for washing;

[0070] In practical applications, the graphite-silver nanoparticle mixture obtained in step 104 can be added to a certain amount of ethanol and washed three times in a centrifuge. The centrifuge speed can be set to 9000 r / min and the washing time can be set to 6 minutes.

[0071] Step 106 : placing the cleaned graphite-silver nanoparticle mixture in an oven for drying to obtain the lithium-ion battery anode material.

[0072] In a specific implementation, the cleaned graphite-silver nanoparticle mixture obtained in step 105 can be placed in an 80° C. oven for drying to obtain the lithium-ion battery anode material provided by the present invention. The specific drying time can be determined according to actual needs.

[0073] Reference Figure 2 , shows a flow chart of the steps of another method for preparing a lithium-ion battery anode material provided by one embodiment of the present invention, which may specifically include the following steps:

[0074] Step 201: etching the spherical graphite to obtain oxidized spherical graphite; wherein the particle size of the spherical graphite is any one of 14 μm, 16 μm, 23 μm and 25 μm; the etching atmosphere of the etching treatment is any one of air atmosphere and carbon dioxide atmosphere; and the etching time range of the etching treatment is 30 minutes to 50 minutes;

[0075] In practical applications, spherical graphite can be used as a base material for lithium-ion battery anode materials, and the spherical graphite is etched in an air atmosphere or a carbon dioxide atmosphere for 30 to 50 minutes, wherein the etching temperature can be 650°C; thereby obtaining oxidized spherical graphite;

[0076] Furthermore, the particle size of spherical graphite can be determined from 14μm, 16μm, 23μm, and 25μm. During the charge and discharge process, the insertion and deintercalation of lithium ions causes the volume of the anode material to expand and contract. The appropriate particle size helps balance the structural stability and electrochemical performance of the battery, reduces cracks or damage caused by volume changes, and improves the battery's cycle stability. Furthermore, etching can be performed in an air atmosphere or a carbon dioxide atmosphere, with the specific etching atmosphere selected based on actual application requirements. The etching time can also be set to 30 minutes to 50 minutes to ensure that the etching process achieves the desired effect.

[0077] Step 202: Stirring the oxidized spherical graphite and a silver salt solution at room temperature to obtain a graphite-silver salt solution; wherein the silver salt solution is any one of a silver nitrate solution and a silver acetate solution; and the concentration of the silver salt solution is 0.1 mol / L to 0.3 mol / L.

[0078] In a specific implementation, the oxidized spherical graphite obtained in the above step can be stirred with a silver salt solution at room temperature for 2 hours to obtain a graphite-silver salt solution; the specific stirring time can be appropriately adjusted according to actual needs; the silver salt solution can be selected from a silver nitrate solution and a silver acetate solution; and the concentration range of the silver salt solution can be 0.1 mol / L to 0.3 mol / L to ensure the surface modification effect.

[0079] Step 203, placing the graphite-silver salt solution in a drying oven for drying to obtain a graphite-silver salt solid mixture;

[0080] In a specific implementation, the graphite-silver salt solution can be placed in a drying oven at 100° C. for drying to obtain a graphite-silver salt solid mixture.

[0081] Step 204: calcining the graphite-silver salt solid mixture in a tube furnace and protecting it with argon gas to obtain a graphite-silver nanoparticle mixture; wherein the calcination temperature range of calcining the graphite-silver salt solid mixture in the tube furnace is 400° C. to 600° C. and the calcination time is 2 hours.

[0082] In practical applications, the graphite-silver salt solid mixture can be placed in a tube furnace and burned for 2 hours with argon protection to obtain a graphite-silver nanoparticle mixture; the burning temperature range can also be set to 400°C to 600°C and the burning time can be set to 2 hours to ensure sufficient burning and achieve the ideal surface modification effect.

[0083] Step 205, adding the graphite-silver nanoparticle mixture to ethanol and placing it in a centrifuge for washing;

[0084] In practical applications, the graphite-silver nanoparticle mixture obtained in step 204 can be added to a certain amount of ethanol and washed three times in a centrifuge. The centrifuge speed can be set to 9000 r / min and the washing time can be set to 6 minutes.

[0085] Step 206 : placing the cleaned graphite-silver nanoparticle mixture in an oven for drying to obtain the lithium-ion battery anode material.

[0086] In a specific implementation, the cleaned graphite-silver nanoparticle mixture obtained in step 205 can be placed in an 80° C. oven for drying to obtain the lithium-ion battery anode material provided by the present invention. The specific drying time can be determined according to actual needs.

[0087] Furthermore, the lithium-ion battery anode material provided by the present invention will be characterized and its performance evaluated in combination with relevant spectra or data.

[0088] Reference Figure 3 , shows a flow chart of the steps of another method for preparing a lithium-ion battery anode material provided by one embodiment of the present invention, which may specifically include the following steps:

[0089] Step 301: etching the spherical graphite to obtain oxidized spherical graphite; wherein the particle size of the spherical graphite is any one of 14 μm, 16 μm, 23 μm and 25 μm; and the etching atmosphere is any one of air atmosphere and carbon dioxide atmosphere;

[0090] In practical applications, spherical graphite can be used as a base material for lithium-ion battery anode materials, and the spherical graphite is etched in an air atmosphere or a carbon dioxide atmosphere for 30 to 50 minutes, wherein the etching temperature can be 650°C; thereby obtaining oxidized spherical graphite;

[0091] Furthermore, the particle size of spherical graphite can be determined from 14μm, 16μm, 23μm, and 25μm. During the charge and discharge process, the insertion and deinsertion of lithium ions will cause the volume of the anode material to expand and contract. The appropriate particle size helps to balance the structural stability and electrochemical performance of the battery, reduce cracks or damage caused by volume changes, and improve the cycle stability of the battery. Furthermore, etching can be performed in an air atmosphere or a carbon dioxide atmosphere, and the specific etching atmosphere can be selected according to the actual application requirements.

[0092] Step 302: Stirring the oxidized spherical graphite and a silver salt solution at room temperature to obtain a graphite-silver salt solution; wherein the silver salt solution is any one of a silver nitrate solution and a silver acetate solution; and the concentration of the silver salt solution is 0.1 mol / L to 0.3 mol / L.

[0093] In a specific implementation, the oxidized spherical graphite obtained in the above step can be stirred with a silver salt solution at room temperature for 2 hours to obtain a graphite-silver salt solution; the specific stirring time can be appropriately adjusted according to actual needs; the silver salt solution can be selected from a silver nitrate solution and a silver acetate solution; and the concentration range of the silver salt solution can be 0.1 mol / L to 0.3 mol / L to ensure the surface modification effect.

[0094] Step 303: placing the graphite-silver salt solution in a drying oven for drying to obtain a graphite-silver salt solid mixture;

[0095] In a specific implementation, the graphite-silver salt solution can be placed in a drying oven at 100° C. for drying to obtain a graphite-silver salt solid mixture.

[0096] Step 304: placing the graphite-silver salt solid mixture in a tube furnace for calcination while protecting it with argon gas to obtain a graphite-silver nanoparticle mixture;

[0097] In practical applications, the graphite-silver salt solid mixture can be placed in a tube furnace and burned for 2 hours with argon protection to obtain a graphite-silver nanoparticle mixture; the burning temperature range can also be set to 400°C to 600°C and the burning time can be set to 2 hours to ensure sufficient burning and achieve the ideal surface modification effect.

[0098] Step 305, adding the graphite-silver nanoparticle mixture to ethanol and placing it in a centrifuge for washing;

[0099] In practical applications, the graphite-silver nanoparticle mixture obtained in step 304 can be added to a certain amount of ethanol and washed three times in a centrifuge. The centrifuge speed can be set to 9000 r / min and the washing time can be set to 6 minutes.

[0100] Step 306 : placing the cleaned graphite-silver nanoparticle mixture in an oven for drying to obtain the lithium-ion battery anode material.

[0101] In a specific implementation, the cleaned graphite-silver nanoparticle mixture obtained in step 205 can be placed in an 80° C. oven for drying to obtain the lithium-ion battery anode material provided by the present invention. The specific drying time can be determined according to actual needs.

[0102] Reference Figure 4 , shows the XRD spectra of the mixed anode, spherical graphite and silver provided by an embodiment of the present invention, in which the horizontal axis is the diffraction angle, that is, twice the angle between the incident X-ray and the diffracted X-ray. The vertical axis is the diffraction intensity, that is, the relative intensity or counting rate of the X-ray detected at a specific diffraction angle 2θ. The diffraction intensity can be the count per unit time, or other related intensity measurement indicators. It is mainly used to reflect the diffraction ability of the material structure to X-rays at a specific angle. It can be seen from the content of the figure that the silver nanoparticles on the surface of the spherical graphite exist in the form of a single substance, that is, the silver nanoparticles in the graphite-silver nanoparticle mixture exist in the form of a single substance on the surface of the spherical graphite.

[0103] Further, refer to Figure 5 , shows a graph showing the voltage change curve of a graphite anode and a mixed anode at a current density of 0.2C provided by an embodiment of the present invention; the black line in the figure is the mixed anode (i.e., the lithium ion battery anode material provided by the present invention), the gray line is the graphite anode, the abscissa is the energy density, and the ordinate is the electrode potential (voltage) relative to the lithium / lithium ion reference electrode (Li / Li + ) value, that is, the difference between the voltage of the battery or electrode and the standard lithium electrode voltage. It can be seen from the content in the figure that when the voltage is reduced to below 0V, the potential distribution of the hybrid anode modified by silver nanoparticles is flatter and there is no lithium metal nucleation overpotential.

[0104] and Figure 6 The discharge to 370 mAh g is provided by an embodiment of the present invention. -1 The SEM (scanning electron microscope) image of the mixed anode is Figure 6 It can be seen that when the mixed anode half-cell is discharged to 370 mAh g -1 When the metal lithium selectively nucleates on the silver nanoparticles, further, Figure 7Discharge to 500mAh g provided by an embodiment of the present invention -1 The SEM image of the mixed anode shows that when the discharge capacity increases to 500 mAh g -1 When the lithium metal is deposited on the surface of the spherical graphite-silver, the lithium metal diffuses on the surface of the spherical graphite-silver. As the lithium metal deposition increases, the lithium metal gradually covers the surface of the spherical graphite-silver to form a smooth lithium metal layer.

[0105] Further, such as Figure 8 The figure shows the cycle performance test results of the hybrid anode half-cell provided by one embodiment of the present invention at a current density of 0.2C. The horizontal axis in the figure is the cycle number, the vertical axis (left) is the energy density, and the vertical axis (right) is the coulombic efficiency. It can be seen from the content in the figure that at a current density of 0.2C, the capacity reaches 500mAh g -1 When the hybrid anode half-cell cycles 100 times, the average Coulombic efficiency is 97.3%.

[0106] The lithium-ion battery anode material provided by the present invention is a hybrid anode that forms a dual mechanism of lithium ion insertion / deinsertion and metal lithium plating / stripping by modifying the surface of spherical graphite with silver nanoparticles. + During intercalation, when the voltage drops below 0V, metallic lithium begins to nucleate. Silver nanoparticles exhibit zero overpotential during the lithium metal deposition process, which can effectively control the lithium metal deposition site, effectively control the selective deposition of lithium metal, inhibit the formation of lithium dendrites, and inhibit the formation of "dead lithium" caused by continuous consumption of electrolyte, thereby improving the coulombic efficiency and theoretical gram capacity of the graphite anode, and further improving the energy density of the lithium battery system. The method for preparing the lithium ion battery anode material provided by the present invention has the advantages of simple process and easy matching with the improved scheme of the diaphragm or electrolyte.

[0107] It should be noted that for the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should be aware that the embodiments of the present invention are not limited by the order of the actions described, because according to the embodiments of the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present invention.

[0108] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0109] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0110] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device comprising a series of elements includes not only those elements, but also other elements not explicitly listed. In the absence of further restrictions, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or terminal device comprising the above elements.

[0111] The above is a detailed introduction to a lithium-ion battery anode material and a preparation method provided. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A lithium ion battery anode material, characterized in that The lithium-ion battery anode material includes a base material and a surface modification material, and the surface modification material is used to perform surface modification on the base material; The substrate material is spherical graphite, the surface modification material is silver nanoparticles, the lithium-ion battery anode material is a graphite-silver nanoparticle mixture obtained by surface modification of the spherical graphite by the silver nanoparticles, and the silver nanoparticles in the graphite-silver nanoparticle mixture exist in the form of a single substance on the surface of the spherical graphite; The particle size of the spherical graphite is any one of 14 μm, 16 μm, 23 μm and 25 μm; The spherical graphite is spherical graphite that has been etched; The etching atmosphere of the etching process is any one of an air atmosphere and a carbon dioxide atmosphere.

2. The lithium-ion battery anode material according to claim 1, characterized in that The graphite-silver nanoparticle mixture is obtained by immersing the spherical graphite in a silver salt solution and performing heat treatment; the silver salt solution is any one of a silver nitrate solution and a silver acetate solution.

3. A method for preparing a lithium ion battery anode material, characterized in that: The method comprises: Etching the spherical graphite to obtain oxidized spherical graphite; stirring the oxidized spherical graphite and the silver salt solution at room temperature to obtain a graphite-silver salt solution; placing the graphite-silver salt solution in a drying oven for drying to obtain a graphite-silver salt solid mixture; placing the graphite-silver salt solid mixture in a tube furnace for burning while protecting it with argon gas to obtain a graphite-silver nanoparticle mixture; adding the graphite-silver nanoparticle mixture into ethanol and placing it in a centrifuge for washing; placing the washed graphite-silver nanoparticle mixture in an oven for drying to obtain the lithium-ion battery anode material; The particle size of the spherical graphite is any one of 14 μm, 16 μm, 23 μm and 25 μm; the etching atmosphere of the etching process is any one of air atmosphere and carbon dioxide atmosphere.

4. The method for preparing a lithium ion battery anode material according to claim 3, wherein: The silver salt solution is any one of a silver nitrate solution and a silver acetate solution; the concentration of the silver salt solution is 0.1 mol / L to 0.3 mol / L.

5. The method for preparing a lithium ion battery anode material according to claim 3, wherein: The graphite-silver salt solid mixture is placed in a tube furnace for calcination at a temperature ranging from 400° C. to 600° C. and for a calcination time of 2 hours.

6. The method for preparing a lithium ion battery anode material according to claim 3, wherein: The etching time of the etching process ranges from 30 minutes to 50 minutes.

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