A method of in-situ production of metal graphene composites

Abstract

The present application relates to a kind of in-situ production metal graphene composite material method, belong to graphene composite material technical field, to solve the problems such as the existing method cannot prepare the composite material of specific content graphene according to need, graphene content is uncontrollable, and the prepared composite material is low in purity, unevenly dispersed, preparation method is complex, cost is high at least one of etc., the present application first prepares master alloy, the carbon content in master alloy greatly exceeds solubility limit, can make carbon in metal melt saturation, form graphene structure, subsequently by adding pure lead to dilute, obtain the target content of lead graphene composite material.The method of the present application can prepare different graphene content metal graphene composite material according to need.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of graphene composite materials, and particularly relates to a method for producing metal graphene composite materials in situ. BACKGROUND

[0002] Graphene is one of the materials with the highest strength, and has good toughness and can be bent. The theoretical Young's modulus of graphene is 1.0 TPa, and the inherent tensile strength is 130 GPa. The carrier mobility of graphene at room temperature is about 15000 cm 2 / (V·s), which is more than 10 times that of silicon material and more than twice that of indium antimonide (InSb), which is the highest known carrier mobility. Under certain conditions such as low temperature, the carrier mobility of graphene can be as high as 250000 cm 2 / (V·s). Unlike many materials, the electron mobility of graphene is less affected by temperature changes. At any temperature between 50 and 500 K, the electron mobility of single-layer graphene is about 15000 cm 2 / (V·s).

[0003] Due to the numerous excellent properties of graphene, it is applied in more and more fields. In recent years, with the rapid development of new energy and energy storage fields, graphene is increasingly used in the field of batteries. For example, graphene is directly added as an additive in active materials to improve the porosity of active materials, enhance the conductivity and charge acceptance of active materials, improve the anti-sulfuration performance and deep cycle performance of batteries, graphene alloy is prepared by adding graphene in the grid alloy, which can improve the conductivity and mechanical properties of the alloy, effectively solve the interface bonding problem between the active material and the grid, avoid premature capacity loss, and greatly improve the corrosion resistance and creep resistance of the grid, effectively prolong the service life of the battery. Due to the excellent properties of graphene alloy, graphene alloy has been widely used in the field of battery energy. The use of graphene in batteries greatly improves various performance indicators of batteries, but the preparation of graphene alloy still has problems such as high cost, poor alloy consistency, uneven dispersion of graphene, low content of graphene, low purity, complex preparation method, and inability to prepare specific content of graphene according to needs. SUMMARY

[0004] In view of the above analysis, the present application aims to provide a method for producing metal graphene composite materials in situ, which at least solves one of the problems that the existing method cannot prepare composite materials with specific content of graphene according to needs, the content of graphene is uncontrollable, and the prepared composite materials have low purity, uneven dispersion, complex preparation method, and high cost.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A method for producing metal-graphene composite material in situ, comprising: preparing a master alloy of metal-graphene composite material, melting the master alloy and metal at 350-400 DEG C, stirring uniformly, pouring into a second mold to obtain the metal-graphene composite material.

[0007] Wherein, the mass relationship of the metal and the master alloy is as follows:

[0008]

[0009] Mpure: the mass of metal, unit g;

[0010] Cinitial: the mass fraction of graphene in the master alloy;

[0011] Minitial: the mass of the master alloy, unit g;

[0012] Crequired: the mass fraction of graphene in the metal-graphene composite material to be prepared.

[0013] Further, the second mold is preheated at 250-300 DEG C for 1-2 h.

[0014] Further, the master alloy is prepared by the following method:

[0015] (1) melting KCl and ZnCl2 to obtain a mixed molten salt, cooling, crushing to obtain a mixed salt, mixing the mixed salt with boron carbide to obtain a mixture;

[0016] (2) adding the mixture to metal or metal alloy, loading into a silicon carbide crucible, placing in a heating and stirring device, heating and melting, standing and layering, the upper layer being a molten salt mixture and the lower layer being the master alloy.

[0017] Further, in step (1), the molar ratio of KCl to ZnCl2 is 1:0.7-1.6, preferably 1:0.7-1.5.

[0018] Further, in step (1), the melting temperature is 750-850 DEG C and the dehydration time is 20-50 min.

[0019] Further, in step (1), the mass of boron carbide accounts for 2-5% of the total mass of KCl and ZnCl2, preferably 3-5%.

[0020] Further, in step (2), the mass of metal or metal alloy is 1-1.6 times, preferably 1-1.5 times, the total mass of KCl and ZnCl2.

[0021] Further, in step (2), the temperature for heating and melting is 650-750℃, and the time is 1-3h.

[0022] Further, the metal is at least one of lead, aluminum or zinc.

[0023] Further, the method further comprises pouring the upper layer of the static layered molten salt mixture into a container made of refractory ceramic or stainless steel, and pouring the remaining small amount of molten salt mixture and the lower layer of substance into the first mold to obtain the master alloy.

[0024] Further, the first mold needs to be preheated at a temperature of 250-300℃ for 1-2h.

[0025] In a second aspect, the present application provides a metal-graphene composite material prepared by the above method.

[0026] In a third aspect, the present application provides an application of the above metal-graphene composite material in battery materials.

[0027] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0028] (1) The present application first prepares a master alloy, and the carbon content in the master alloy greatly exceeds the solubility limit, which can saturate the carbon in the metal melt to form a graphene structure, and then dilute by adding metal to obtain a metal-graphene composite material with a target content. The method of the present application can prepare metal-graphene composite materials with different graphene contents according to needs.

[0029] (2) In the preparation method of the master alloy in the present application, KCl and ZnCl2 are first melted, which on the one hand makes the salt fully dehydrated, and on the other hand reduces the melting point of the mixed salt after melting, and the required temperature is lower during secondary melting, which is conducive to the reaction and can improve the content of graphene. In the present application, by increasing the pretreatment of molten salt, the metal or metal alloy can be melted at a lower temperature, which is more conducive to the reaction, further improves the content of graphene in the product, and is also conducive to reducing the size and number of layers of graphene and improving the purity of the composite material. The purity of the composite material of the present application is ≥99%, the content of graphene is ≥0.0014%, and preferably, the content of graphene is 0.023%;

[0030] (3) The metal master alloy is prepared in an induction furnace, in which, due to the electric power, the convection of the metal melt is ensured, and the mixing of the metal melt is realized. The molten salt has no conductivity, so it can only heat the molten metal and will not move under the action of electromagnetic force. The convection in the molten salt is essentially only a heat flow, the salt heated by the metal rises from the molten metal-salt interface to the salt-ambient interface in the furnace, and is replaced by the cooler salt, which ensures the continuous movement of the molten metal-salt interface, and the method of the application has lower energy consumption and is more convenient to operate, without the need for additional mechanical stirring treatment.

[0031] The technical solutions described above can also be combined with each other in the present application to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent description, and some advantages will become apparent from the description, or will be understood by implementing the present application. The purposes and other advantages of the present application can be achieved and obtained through the contents specifically pointed out in the description and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated herein and constitute a part of the present application. The same reference numerals in the drawings refer to the same elements throughout.

[0033] Figure 1 SEM image of the composite material prepared for example 1 of the present application;

[0034] Figure 2 BES image of the composite material prepared for example 1 of the present application;

[0035] Figure 3 Raman spectrum of the composite material prepared for example 1 of the present application. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present application will be specifically described below in combination with the drawings, wherein the drawings constitute a part of the present application, and are used to explain the principles of the embodiments of the present application, and are not used to limit the scope of the present application.

[0037] One specific embodiment of the present application discloses a method for producing metal graphene composite material in situ, comprising: preparing a master alloy of metal graphene composite material, melting the master alloy and metal at 350-400 DEG C, stirring uniformly, pouring into a second mold, and obtaining the metal graphene composite material.

[0038] The mass relationship of the metal and the master alloy is as follows:

[0039]

[0040] Mpure: the mass of the metal, unit g;

[0041] Cinitial: mass fraction of graphene in master alloy;

[0042] Minitial: mass of master alloy, unit g;

[0043] Cdesired: mass fraction of graphene in metal graphene composite material to be prepared.

[0044] Compared with the prior art, the application adopts a graphene film for metal strengthening technology, that is, the carbon content in the melt greatly exceeds the solubility limit, and then the graphene structure is released during the crystallization (from liquid to solid) process (to enhance the mechanical properties of the lead-graphene composite); the application first prepares a master alloy, the carbon content in the master alloy greatly exceeds the solubility limit, so that the carbon can be saturated in the metal melt to form a graphene structure, and then the metal is added for dilution to obtain a metal graphene composite material with a target content. The method of the application can prepare metal graphene composite materials with different graphene contents as required.

[0045] The application prepares a metal graphene composite material in the form of a master alloy, first prepares a master alloy with a high graphene content, and the master alloy can be mixed with metal or a conventional metal alloy at a certain ratio and then used. Because special materials and equipment are required for the production of graphene composite materials, the application can realize that the production party produces the master alloy and delivers it to the user for dilution and use, thereby reducing the production cost and transportation cost.

[0046] In a specific embodiment, the second mold is preheated at 250-300°C (for example, 250°C, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C) for 1-2h (for example, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h).

[0047] If the mold temperature is too low, the cooling speed of the lead will be too fast, large shrinkage holes will be generated, and the subsequent use will be affected; if the mold temperature is too high, the cooling speed of the lead will be too slow, and composition segregation will occur.

[0048] In a specific embodiment, the master alloy is prepared by the following method:

[0049] (1) KCl and ZnCl2 are melted to obtain a mixed molten salt, which is cooled, crushed to obtain a mixed salt, and mixed with boron carbide to obtain a mixture;

[0050] (2) The mixture is added to metal or metal alloy, loaded into a silicon carbide crucible, and placed in a heating and stirring device for heating and melting, and then left to stratify, and the upper layer is a molten salt mixture, and the lower layer is the master alloy.

[0051] In the preparation method of the master alloy in the present application, KCl and ZnCl2 are first melted, on the one hand to dehydrate the salt, and on the other hand to reduce the melting point of the mixed salt after melting, so that the temperature required in the secondary melting is lower, which is conducive to the reaction and can improve the content of graphene. In the present application, by increasing the pretreatment of molten salt, melting with metal or metal alloy can be carried out at a lower temperature, which is more conducive to the reaction, further improves the content of graphene in the product, and also helps to reduce the size and number of layers of graphene and improve the purity of the composite material.

[0052] The carbon source in the method of the present application comes from boron carbide, which decomposes under certain conditions to form carbon atoms into lead liquid, and recombines to form graphene structure after reaching a certain concentration. Therefore, the graphene in the master alloy prepared by the method of the present application has better combination with lead and is more uniformly dispersed. Secondly, graphene is expensive, and compared with the direct addition of graphene, the method of the present application has cost advantage.

[0053] Preferably, the heating and stirring device in the present application is an induction furnace. The carbon content in the master alloy prepared by the method of the present application greatly exceeds the solubility limit, the preparation method is simple, the preparation time is short, the production cost is low, mechanical stirring is not used, the reaction is carried out by using an induction furnace, which can reduce the impurities introduced due to stirring, can omit the stirring step, simplify the operation, and in addition, the induction furnace has fast heating, which can shorten the heating and melting time.

[0054] In one specific embodiment, in step (1), the molar ratio of KCl to ZnCl2 is 1:0.7-1.6, preferably 1:0.7-1.5, for example, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5.

[0055] The mixed salt of KCl and ZnCl2 has a lower melting point than single salt, and in the above molar ratio range, the melting point is relatively low near the eutectic point of KCl and ZnCl2.

[0056] Experiments show that the carbon separates from the salt and enters the lead, which is related to the type of salt and temperature. The salt and temperature selected in the present application are more conducive to this process. In order to ensure that the carbon provides more effective exchange between the phase boundary of the metal and the salt residue carrier, the salt residue adopts KCl and ZnCl2.

[0057] In one embodiment, the temperature of the melting is 750-850℃, for example, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, and the time of the melting is 20-50min, for example, 20min, 25min, 30min, 35min, 40min, 45min, 50min.

[0058] At the above-mentioned temperature and time, the KCl and ZnCl2 can be fully melted, and the energy consumption is low, and the service life of the equipment is not affected.

[0059] In one embodiment, the particle size of the crushed KCl and ZnCl2 is less than 3mm, which is beneficial to the uniform mixing with the boron carbide.

[0060] In one embodiment, the mass of the boron carbide accounts for 2-5% of the total mass of the KCl and ZnCl2, preferably 3-5%, for example, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, 5%. Since the boron carbide is a carbon source, it must be in excess to ensure that there is enough graphene content in the product.

[0061] In one embodiment, the mass of the metal or metal alloy is 1-1.6 times, preferably 1-1.5 times, for example, 1 times, 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, of the total mass of the KCl and ZnCl2.

[0062] In one embodiment, the temperature of the heating and melting is 650-750℃, for example, 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, and the time is 1-3h, for example, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2.0h, 2.2h, 2.4h, 2.6h, 2.8h, 3h.

[0063] A lower temperature is not conducive to the reaction, and a higher temperature will increase the loss of salt volatilization and energy consumption, so the above-mentioned temperature range is selected. The time is related to the content of graphene, and the longer the time, the higher the content.

[0064] The metal master alloy is prepared in an induction furnace, in which, due to the electric power, the convection of the metal melt is ensured, and the mixing of the metal melt is realized. The molten salt has no conductivity, so it can only heat the molten metal and will not move under the action of electromagnetic force. The convection in the molten salt is essentially a heat flow, the salt heated by the metal rises from the molten metal-salt interface to the salt-atmosphere interface in the furnace, and is replaced by the cooler salt, which ensures the continuous movement of the molten metal-salt interface. This is because boron carbide and salt are mixed together, the salt at the metal-salt interface moves upward under the action of heat flow, the cooler salt at the upper part sinks, and the boron carbide also moves in the same way, the material at the metal-salt interface is always changing, thereby playing a stirring role, and no additional mechanical stirring is required.

[0065] In a specific embodiment, the method further comprises pouring the upper layer of the static layered molten salt mixture into a container made of refractory ceramic or stainless steel, and pouring the remaining small amount of molten salt mixture and the lower layer of material into the first mold to obtain the master alloy.

[0066] Specifically, the first mold needs to be preheated at a temperature of 250-300°C (for example, 250°C, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C) for 1-2h (for example, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h).

[0067] If the mold temperature is too low, the cooling speed of the lead will be too fast, resulting in large shrinkage holes and affecting subsequent use; if the mold temperature is too high, the cooling speed of the lead will be too slow, which will cause composition segregation.

[0068] It should be noted that the first mold is preheated in a low-temperature resistance furnace, and the low-density molten salt floats up in the form of slag and can be easily separated from the ingot after being taken out of the mold. The separated molten salt can be used in step (1).

[0069] In the present application, the purity of pure lead is 99.99%, the purity of KCl is 99.8%, the purity of ZnCl2 is 99.8%, the purity of boron carbide is ≥96.0%, and the particle size of boron carbide is at least F220.

[0070] In a specific embodiment, the content of graphene in the master alloy is 0.015-0.025%, and the hardness is 4.8-5.0 HB.

[0071] Preferably, the content of graphene in the master alloy is 0.023-0.025%, and the hardness is 4.9-5.0 HB.

[0072] In one embodiment, the carbon in the master alloy is modified to graphene.

[0073] In one embodiment, the metal is at least one of lead, aluminum or zinc.

[0074] The purity of the master alloy prepared by the method is ≥99.93%, and the purity of the metal graphene composite material is ≥99.96%.

[0075] In another embodiment of the present application, a metal graphene composite material prepared by the above method is disclosed.

[0076] Preferably, the metal graphene composite material prepared by the present application has at least 2 layers of graphene, preferably 2 layers, a purity of ≥99.6%, a graphene content of 0.0014-0.023%, preferably a graphene content of 0.023%, and a hardness of 4.6-4.7 HB.

[0077] In another embodiment of the present application, the use of the above metal graphene composite material in battery materials is disclosed.

[0078] The technical solutions of the present application are further explained in combination with specific embodiments.

[0079] In the following embodiments of the present application, the purity of pure lead is 99.99%, the purity of KCl is 99.8%, the purity of ZnCl2 is 99.8%, the purity of boron carbide is 96.0%, and the particle size of boron carbide is F220.

[0080] Embodiment 1

[0081] A method for in-situ production of a metal graphene composite material, comprising the following steps:

[0082] (1) Mix KCl and ZnCl2 according to a molar ratio of 1:1 (total mass of 450g), load into a silicon carbide crucible in a Graficarbo resistance furnace, melt and dehydrate at a temperature of 750℃ for 40min, cool, crush to a particle size of less than 3mm, add 15g of boron carbide, and obtain a mixture;

[0083] (2) 600 g of pure lead is mixed with the mixture, loaded into a silicon carbide crucible, and placed in a YiHui M.MF.00004 induction furnace, heated and melted at a temperature of 700°C for 2 h, to obtain two layers of material, the upper layer being a molten salt mixture and the lower layer being a master alloy. The molten salt mixture is poured into a container made of refractory ceramic or stainless steel, and the remaining small amount of molten salt mixture and master alloy are poured into a first metal mold, which is preheated to 300°C in a low-temperature resistance furnace SNOL 58 / 350 for 1 h. The low-density molten salt floats up as a slag and is easily separated from the master alloy ingot after being removed from the first mold. The carbon content in the master alloy is 0.025%, and the modification of carbon is graphene, which is checked on a Renishaw INVIA0820-04 confocal Raman scattering spectrometer;

[0084] (3) To obtain a metal graphene composite material with a mass fraction of graphene of 0.0023%, 50 g of master alloy and 493 g of pure lead are melted at 370°C, the melt is kept at a given temperature for 15 min, then manually mixed with a stainless steel stirrer, and the surface slag is removed with a stainless steel skimmer until the metal is mirror-like. Pour into a second metal mold preheated to 290°C for 1 h to obtain a metal graphene composite material.

[0085] Example 2

[0086] A method for in-situ production of metal graphene composite material, comprising the following steps:

[0087] (1) KCl and ZnCl2 are mixed in a molar ratio of 1:0.7, loaded into a silicon carbide crucible in a Graficarbo resistance furnace, and melted and dehydrated at a temperature of 850°C for 50 min, then cooled and crushed to a particle size of less than 3 mm, and boron carbide is added, the mass of boron carbide being 4% of the total mass of KCl and ZnCl2, to obtain a mixture;

[0088] (2) The pure lead is mixed with the mixture, the mass of the pure lead is 1 times the total mass of KCl and ZnCl2, and is loaded into a silicon carbide crucible and placed in a YiHui M.MF.00004 induction furnace. The temperature is 750°C, and the melting is heated for 1 h. Two layers of substances are obtained, the upper layer is a molten salt mixture, and the lower layer is a master alloy. The molten salt mixture is poured into a container made of refractory ceramic or stainless steel. The remaining small amount of molten salt mixture and the master alloy are poured into a first metal mold. The first metal mold is preheated to 300°C in a low-temperature resistance furnace SNOL 58 / 350 for 1 h. The low-density molten salt floats up in the form of slag and is easily separated from the master alloy ingot after being taken out of the first mold. The carbon content in the master alloy is 0.024% after being checked on a Renishaw INVIA0820-04 confocal Raman scattering spectrometer, and the modification of carbon is graphene;

[0089] (3) In order to obtain a metal graphene composite material with a mass fraction of graphene of 0.0023%, 50g of the master alloy and 472g of pure lead are melted at 400°C. The melt is kept at a given temperature for 15 min, and then manually mixed with a stainless steel stirrer. The surface slag is removed with a stainless steel skimmer until the metal is mirror-like. Pour into a second metal mold preheated at a temperature of 250°C for 2 h to obtain a metal graphene composite material.

[0090] Example 3

[0091] A method for in-situ production of a metal graphene composite material, comprising the following steps:

[0092] (1) KCl and ZnCl2 are mixed in a molar ratio of 1:1.5, loaded into a silicon carbide crucible in a Graficarbo resistance furnace, and melted and dehydrated at a temperature of 800°C for 50 min. Cool and crush to a particle size of less than 3 mm. Add boron carbide, and the mass of boron carbide is 5% of the total mass of KCl and ZnCl2 to obtain a mixture;

[0093] (2) The lead is mixed with the mixture, the mass of pure lead is 1.5 times the total mass of KCl and ZnCl2, and is loaded into a silicon carbide crucible and placed in a YiHui M.MF.00004 induction furnace, and is heated and melted at a temperature of 650℃ for 3h to obtain two layers of substances, the upper layer is a molten salt mixture, and the lower layer is a master alloy, the molten salt mixture is poured into a container made of refractory ceramic or stainless steel, and the remaining small amount of molten salt mixture and master alloy are poured into a first metal mold, wherein the first metal mold is preheated to 275℃ in a low-temperature resistance furnace SNOL 58 / 350 for 1.5h, the low-density molten salt floats up in the form of slag, and is easily separated from the master alloy ingot after being taken out of the first mold, wherein the carbon modification is checked on a Renishaw INVIA0820-04 confocal Raman scattering spectrometer, the carbon content in the master alloy is 0.023%, and the modification of carbon is graphene;

[0094] (3) In order to obtain a metal graphene composite material with a graphene mass fraction of 0.0023%, 50g of master alloy and 450g of pure lead are melted at 350℃, the melt is kept at a given temperature for 15min, and then manually mixed with a stainless steel stirrer, and the surface slag is removed with a stainless steel skimmer until the metal is mirror-like; poured into a second metal mold preheated at a temperature of 300℃ for 1.5h to obtain a metal graphene composite material.

[0095] Example 4

[0096] The preparation method of a metal graphene composite material in this example is the same as that in Example 1, except that in step (1), the molar ratio of KCl to ZnCl2 is 1:1.6.

[0097] Example 5

[0098] The preparation method of a metal graphene composite material in this example is the same as that in Example 1, except that in step (1), the mass of boron carbide accounts for 2% of the total mass of KCl and ZnCl2.

[0099] Example 6

[0100] The preparation method of a metal graphene composite material in this example is the same as that in Example 1, except that in step (2), the mass of lead is 1.6 times the total mass of KCl and ZnCl2.

[0101] Comparative Example 1

[0102] The preparation method of a metal graphene composite material in this example is the same as that in Example 1, except that in step (1), KCl, ZnCl2 and boron carbide are mixed directly, and KCl and ZnCl2 are not subjected to melting, cooling and crushing.

[0103] Comparative Example 2

[0104] The preparation method of the metal graphene composite material of the present comparative example is the same as that of Example 1, except that in step (2), the temperature of heating and melting is 760℃, and the time is 2.2h.

[0105] Comparative Example 3

[0106] The preparation method of the metal graphene composite material of the present comparative example is the same as that of Example 1, except that in step (2), instead of using an induction furnace to heat and melt, an open furnace is used to melt in a mechanical stirrer.

[0107] Comparative Example 4

[0108] The preparation method of the metal graphene composite material of the present comparative example is the same as that of Example 1, except that in step (3), the temperature of melting is 410℃.

[0109] Comparative Example 5

[0110] The preparation method of the metal graphene composite material of the present comparative example is the same as that of Example 1, except that ZnCl2 is replaced by NaCl.

[0111] Test Example 1

[0112] The purity, graphene content and layer number of the master alloys and metal graphene composite materials prepared in Examples 1-6 and Comparative Examples 1-5 were tested respectively, and the hardness of the composite materials was tested by VERZUS 750CCD hardness tester, and the results are shown in Table 1.

[0113] Among them, the graphene layer number detection method is as follows:

[0114] In the present application, the number of graphene layers is characterized by Raman spectroscopy, and the number of graphene layers is calculated by the intensity relationship of 2D peak and G peak. Renishaw INVIA0820-04 confocal Raman scattering spectrometer is used for testing.

[0115] Figure 3 The Raman spectrum test results of Example 1 are shown, and the Raman spectrum shows that the test sample is a typical multi-layer graphene structure. According to the intensity ratio I2D / IG of 2D and G peaks is equal to 0.60, it shows that the material at this test point forms two layers of graphene. The G peak is obviously higher than the D peak, indicating that the number of graphene defects is small. The products obtained in other examples or comparative examples are also tested by the same method.

[0116] Table 1

[0117]

[0118] Comparative Example 1 does not use the raw material pretreatment process designed in the application, the prepared master alloy has a significantly reduced graphene content, the purity and hardness of the composite material are also slightly reduced, and the number of graphene layers is increased to 3 layers.

[0119] Examples 4-6 have a reduced graphene content in the prepared master alloy compared to Example 1, wherein the purity of the composite material in Example 4 is also reduced, and the number of graphene layers is increased to 3 layers.

[0120] Comparative Example 2 has a significantly reduced graphene content in the prepared metal graphene composite material compared to Example 1, and the purity and hardness of the composite material are also slightly reduced.

[0121] Comparative Example 3 has a substantially consistent graphene content in the prepared master alloy compared to Example 1, but the ordinary melting furnace has a slow heating rate, and mechanical stirring makes the production process more complicated. Moreover, the introduction of impurities due to mechanical stirring reduces the purity of the composite material.

[0122] Comparative Example 4 has a significantly reduced graphene content in the prepared metal graphene composite material compared to Example 1.

[0123] Comparative Example 5 has a significantly reduced graphene content in the prepared master alloy compared to Example 1.

[0124] Test Example 2

[0125] The graphene composite material obtained in Example 1 was sampled at different positions, and the carbon content was tested, and the data obtained are shown in Table 2. The microscopic morphology of the cross section of the composite material was observed, and the SEM and BES images are shown in Figure 1 and 2 .

[0126] Table 2 Carbon content test data of graphene composite material at different positions

[0127] Position number Carbon content (%) 1 0.0024 2 0.0025 3 0.0026 4 0.0025 5 0.0025 6 0.0027 7 0.0023 8 0.0025

[0128] From the above table, it can be seen that the carbon content in the graphene composite material at different positions is not much different, indicating that the consistency of the composite material prepared by the method of the application is good.

[0129] From Figure 1 and 2 , it can be seen that the graphene film size in the graphene composite material prepared by the method of the application is small and uniformly dispersed, without agglomeration or caking.

[0130] The inventors conducted the above tests on the composite materials prepared in other examples, and the results were basically consistent. Due to the limited space, they are not listed one by one.

[0131] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for in-situ production of metal-graphene composite materials, characterized in that, include: To prepare the master alloy for the metal-graphene composite material, the master alloy and the metal are melted at 350~400℃, stirred evenly, and poured into a second mold to obtain the metal-graphene composite material. The mass relationship between the metal and the master alloy is as follows: ； M_pure: Mass of the metal, in grams; Cinitial: The mass fraction of graphene in the master alloy; Minitial: Mass of the master alloy, in grams; C required: The mass fraction of graphene in the desired metal-graphene composite material; The master alloy is prepared by the following method: (1) KCl and ZnCl2 are melted to obtain a mixed molten salt, cooled and crushed to obtain a mixed salt, and the mixed salt is mixed with boron carbide to obtain a mixture; (2) Add the mixture to the metal, place it in a heating and stirring device, heat and melt it, let it stand and separate into layers, the upper layer is the molten salt mixture, and the lower layer is the master alloy.

2. The method for in-situ production of metal graphene composite materials according to claim 1, characterized in that, The second mold is preheated at 250~300℃ for 1-2 hours.

3. The method for in-situ production of metal graphene composite materials according to claim 1, characterized in that, In step (1), the molar ratio of KCl to ZnCl2 is 1:0.7~1.

6.

4. The method for in-situ production of metal graphene composite materials according to claim 1, characterized in that, In step (1), the melting temperature is 750~850℃ and the melting and dehydration time is 20~50min.

5. The method for in-situ production of metal graphene composite materials according to claim 1, characterized in that, In step (1), the mass of boron carbide accounts for 2 to 5% of the total mass of KCl and ZnCl2.

6. The method for in-situ production of metal graphene composite materials according to claim 1, characterized in that, In step (2), the mass of the metal is 1 to 1.6 times the total mass of KCl and ZnCl2; The heating and melting temperature is 650~750℃, and the time is 1~3h.

7. A method for in-situ production of metal graphene composite materials according to any one of claims 1-6, characterized in that, The metal is at least one of lead, aluminum, or zinc.

8. A metal graphene composite material prepared by the method of any one of claims 1-7.

9. The application of the metal graphene composite material according to claim 8 in battery materials.

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