Nonmetal porous carbon negative electrode material and preparation method and application thereof

Abstract

The invention relates to a nonmetal porous carbon negative electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: activating a carbon-containing raw material in a hydrogen-containing mixed gas to obtain porous carbon and benzene-oil-hydrocarbon-rich gas; performing primary deposition on non-metal source gas and the porous carbon; and carrying out secondary deposition on the non-metal porous carbon negative electrode material and the benzene-rich oil hydrocarbon gas to obtain the non-metal porous carbon negative electrode material. The carbon-containing raw material also comprises ash removal before use, or the porous carbon is mixed after being subjected to ash removal. According to the method, the carbon-containing raw material is activated through hydrogen, continuous preparation of the porous carbon and the non-metal porous carbon negative electrode material is achieved, and the surplus hydrogen generated in the process can be recycled to the hydrogen activation step to be reused. The carbon-containing material is efficiently deoxidized through hydrogen activation, other oxide impurities are prevented from being generated in the nonmetal deposition process, the safety of the deposition process can be effectively guaranteed, gas benzene-rich oil hydrocarbon by-products generated in the porous carbon preparation process can further conduct carbon coating on the material, and efficient utilization of carbon-containing resources is achieved.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a non-metallic porous carbon negative electrode material and a preparation method and application thereof. Background Art

[0002] With the proposal of environmental protection and dual carbon goals, my country's requirements for efficient transformation and utilization of traditional fossil energy and new energy technologies are increasing. my country has abundant carbon-containing resources such as coal and biomass, and the main way to utilize traditional carbon-containing resources is direct combustion, which has caused great waste of precious resources. Coal, biomass and petroleum coke are the main raw materials for preparing porous carbon. Since battery-grade porous carbon materials have high added value, the use of the above raw materials to prepare porous carbon has great application prospects.

[0003] The theoretical capacity of porous carbon as the negative electrode of lithium-ion batteries is only 372mAh / g. By depositing silicon (theoretical capacity 4200mAh / g) or phosphorus (theoretical capacity 2596mAh / g) into porous carbon, the silicon-carbon or phosphorus-carbon negative electrode materials prepared will greatly improve the lithium storage performance of porous carbon. However, silicon or phosphorus as negative electrode materials have a high expansion rate and are easy to break. Therefore, by depositing silicon or phosphorus on porous carbon and using porous carbon to act as a volume expansion buffer, the stability of silicon or phosphorus can be further improved, achieving high-capacity and high-stability lithium storage performance.

[0004] The layered structure and good conductivity of phosphorus give it broad development space in the field of alkali metal ion batteries such as sodium ion batteries. As a negative electrode material for sodium ion batteries, phosphorus has a theoretical specific capacity of up to 2596 mAh / g. Therefore, phosphorus is deposited in porous carbon to obtain phosphorus-based hard carbon, which can also be used as an excellent material for improving the capacity and stability of alkali metal ion batteries such as sodium ion batteries.

[0005] At present, the preparation method of porous carbon materials that play a buffering role is mainly to use metal compounds such as ZnCl2 and KOH as activators and pore-forming agents under an inert atmosphere (Ar, N2). This process has high cost and produces metal vapor, HCl and other environmental pollutants, and the residue needs further cleaning, or CO, CO2 and the like are used as pore-forming agents, but the effect is still limited, and deep deoxidation is not possible, which will have an adverse effect on non-metallic deposition in the subsequent preparation of negative electrode materials. At the same time, a large amount of organic matter is released in the form of gas in the process of preparing porous carbon using coal, resulting in a waste of resources. The traditional method of using hydrogen-assisted reduction of coal to prepare oil hydrocarbon products will also produce a large amount of semi-coke by-products, resulting in a waste of resources.

[0006] CN113307267A discloses a method for preparing coal-based porous carbon using alkali metal compounds such as KOH and NaOH as pore-forming agents. The process route is short and the production speed is fast, but the method is costly and the generated alkali metal vapor pollutes the environment. In addition, the porous carbon obtained by adding metal compounds cannot remove oxygen and retains a large number of oxygen defects. If silicon deposition is to be carried out, it will cause silicon combustion and lead to the formation of silicon dioxide.

[0007] CN114890420A discloses a method for preparing coal-based porous carbon. The porous carbon prepared by the method has a multi-level pore structure of micropores and mesopores. The porous carbon material prepared by the method has a high specific capacity, but the overall process route is long. The preparation process requires high-energy ball milling, addition of acid and alkali and other raw materials, which causes great pollution to the environment.

[0008] CN115491221A discloses a method for preparing oil hydrocarbons by hydrogenating and liquefying coal under high pressure. The coal hydrogenating and liquefying methods represented by this process generally produce semi-coke accounting for about 50% of the raw material mass, resulting in serious waste of resources.

[0009] Therefore, how to improve the high cost, environmental pollution and waste of hydrocarbons in the process of preparing porous carbon from carbon-containing natural resources, and how to achieve the continuous preparation of efficient and low-cost non-metallic porous carbon negative electrode materials are technical problems that need to be solved urgently. Summary of the invention

[0010] In order to solve the above technical problems, the present invention provides a non-metallic porous carbon negative electrode material and a preparation method and application thereof. By hydrogen activating carbon-containing raw materials, porous carbon and non-metallic porous carbon negative electrode materials can be continuously prepared. The surplus hydrogen generated in the process can be recycled to the hydrogen activation step and reused. Hydrogen activation allows the carbon-containing material to be efficiently deoxidized, avoiding the generation of other non-metallic oxide impurities during the deposition of non-metals. The gaseous benzene-rich oil hydrocarbon byproducts generated during the activation and preparation of porous carbon can further carbon-coat the material, thereby achieving efficient utilization of carbon-containing resources.

[0011] To achieve this object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a method for preparing a non-metallic porous carbon negative electrode material, the preparation method comprising the following steps:

[0013] (1) activating a carbonaceous raw material in a hydrogen-containing mixed gas to obtain porous carbon and benzene-rich oil hydrocarbon gas;

[0014] (2) mixing the non-metallic source gas with the porous carbon described in step (1) to perform a primary deposition, and mixing the primary deposition product obtained with the benzene-rich hydrocarbon gas described in step (1) to perform a secondary deposition to obtain a non-metallic porous carbon negative electrode material;

[0015] Wherein, the benzene-rich hydrocarbon gas in step (1) includes any one or a combination of at least two of alkanes, aromatic hydrocarbons, alkenes or alkynes;

[0016] The carbon-containing raw material in step (1) is further deashed before use, or the porous carbon in step (1) is deashed before step (2).

[0017] The present invention activates the carbon-containing resources after deashing and purification by hydrogen, and hydrogen also serves as a pore-forming agent, thereby realizing the coordinated production of porous carbon and benzene-rich oil hydrocarbons. In addition, the presence of hydrogen can also achieve the effect of efficient deoxidation, avoiding safety problems caused by high oxygen content in the process of depositing non-metals, and also avoiding the generation of other non-metallic oxide impurities in the process.

[0018] The present invention uses porous carbon and benzene-rich oil hydrocarbon gas as raw materials for preparing non-metallic porous carbon negative electrode materials, wherein the porous carbon has a high specific surface area and can be used as a buffer substrate for the negative electrode material. Non-metals with high expansion rates of negative electrode materials such as silicon, phosphorus or carbon are deposited inside the porous carbon pores to reserve space for their expansion, which can greatly alleviate the problem of high expansion rate of negative electrode materials. At the same time, the porous structure can ensure the rapid passage of lithium ions. In addition, the generated benzene-rich oil hydrocarbon gas by-product can be used as a raw material for carbon coating, so that the carbon-containing raw material is fully utilized. The presence of the carbon coating layer also further plays a buffering role, thereby improving the overall conductivity of the material. The obtained non-metallic porous carbon negative electrode material has a high specific capacity and better cycle performance.

[0019] As a preferred technical solution of the present invention, the carbon-containing raw material in step (1) includes any one of coal, biomass, asphalt or petroleum coke, or a combination of at least two of them.

[0020] Preferably, the coal comprises medium and low rank coal.

[0021] Preferably, the medium and low-rank coal includes any one of bituminous coal, sub-bituminous coal or lignite, or a combination of at least two of them.

[0022] It should be noted that the bituminous coal used in the present invention is low-volatile bituminous coal. According to GB5751-86 "China Coal Classification", the volatile content of low-volatile bituminous coal is in the range of 10% to 20%.

[0023] Preferably, the alkane includes any one of methane, ethane or propane, or a combination of at least two of them.

[0024] Preferably, the aromatic hydrocarbon includes any one of benzene, naphthalene, phenanthrene, pyrene, toluene or ethylbenzene, or a combination of at least two thereof.

[0025] Preferably, the olefin comprises propylene or ethylene.

[0026] Preferably, the alkyne comprises acetylene.

[0027] It should be noted that the present invention can adaptively adjust the specific substance type of the benzene-rich oil hydrocarbon gas according to the specific type of carbon raw material.

[0028] Preferably, the hydrogen-containing mixed gas in step (1) comprises a mixed gas of hydrogen and argon.

[0029] Preferably, in the mixture of hydrogen and argon, the content of hydrogen is 0-5 vol%, and is not 0, for example, 1 vol%, 2 vol%, 3 vol%, 4 vol% or 5 vol%.

[0030] Preferably, the deliming comprises mechanical deliming or chemical deliming.

[0031] In the present invention, deashing can achieve purification of carbon-containing raw materials.

[0032] As a preferred technical solution of the present invention, the activation temperature of step (1) is 700-1000°C, for example, 700°C, 720°C, 750°C, 780°C, 800°C, 820°C, 850°C, 880°C, 900°C, 920°C, 950°C, 980°C or 1000°C, etc.

[0033] In the present invention, if the activation temperature of hydrogen activation is too high, the porous carbon structure will collapse and fail to play a buffering role, and the generation of benzene-rich oil hydrocarbon gas will also be reduced, resulting in a waste of resources; if the activation temperature of hydrogen activation is too low, pore formation will not be achieved, or the pore size after pore formation is too small, the proportion of micropores is too high, and it is difficult to deposit non-metals.

[0034] Preferably, the activation heating rate in step (1) is 0.05 to 15°C / min, for example, 0.05°C / min, 0.1°C / min, 0.5°C / min, 1°C / min, 3°C / min, 5°C / min, 8°C / min, 10°C / min, 12°C / min or 15°C / min, etc.

[0035] Preferably, the activation holding time in step (1) is 1 to 5 h, such as 1 h, 2 h, 3 h, 4 h or 5 h.

[0036] Preferably, the activation pressure in step (1) is 0.1-10 MPa, for example, 0.1 MPa, 0.5 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa or 10 MPa.

[0037] In the present invention, by adjusting the activation temperature, activation pressure and heating rate of hydrogen activation, the coordinated production of porous carbon and benzene-rich oil hydrocarbon gas is achieved, providing raw materials with better performance for the preparation of non-metallic porous carbon negative electrode materials.

[0038] Preferably, the gas flow rate of the mixed gas containing hydrogen and argon in step (1) is 100-500 mL / min, for example, 100 mL / min, 150 mL / min, 200 mL / min, 250 mL / min, 300 mL / min, 350 mL / min, 400 mL / min, 450 mL / min or 500 mL / min, etc.

[0039] As a preferred technical solution of the present invention, the non-metallic source gas in step (2) includes any one of silane, phosphorus vapor, phosphine, phosphorus bromide, triphenylphosphine or alkane.

[0040] Preferably, the alkane includes any one of methane, ethane, propane or butane, or a combination of at least two of them.

[0041] Preferably, the primary deposition method in step (2) comprises vapor deposition.

[0042] Preferably, the temperature of the primary deposition in step (2) is 300-800°C, for example, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C.

[0043] Preferably, the secondary deposition method in step (2) includes vapor deposition.

[0044] Preferably, the temperature of the secondary deposition in step (2) is 300-1000°C, for example, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, etc.

[0045] Preferably, after the secondary deposition in step (2), drying is also included.

[0046] Preferably, the drying temperature is 60-200°C, for example, 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, 180°C or 200°C.

[0047] Preferably, the drying time is 5 to 12 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours.

[0048] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0049] (1) activating the deashed carbonaceous raw material in a mixture of hydrogen and argon at a rate of 0.05 to 15°C / min to 700 to 1000°C, keeping the temperature for 1 to 5 hours, and activating at an activation pressure of 0.1 to 10 MPa to obtain porous carbon and benzene-rich oil hydrocarbon gas;

[0050] Wherein, in the mixed gas of hydrogen and argon, the content of hydrogen is 0-5 vol%, and is not 0; the gas flow rate of the mixed gas containing hydrogen and argon is 100-500 mL / min; the carbon-containing raw material includes any one of coal, biomass, asphalt or petroleum coke, or a combination of at least two; the deashing includes mechanical deashing or chemical deashing; the coal includes medium and low rank coal; the medium and low rank coal includes any one of bituminous coal, sub-bituminous coal or lignite, or a combination of at least two; the benzene-rich oil hydrocarbon gas includes any one of alkanes, aromatic hydrocarbons, olefins or alkynes, or a combination of at least two; the alkane includes any one of methane, ethane or propane, or a combination of at least two; the aromatic hydrocarbon includes any one of benzene, naphthalene, phenanthrene, pyrene, toluene or ethylbenzene, or a combination of at least two; the olefin includes propylene or ethylene; the alkyne includes acetylene;

[0051] (2) The non-metallic source gas and the porous carbon described in step (1) are subjected to a primary deposition at 300-800° C. by a vapor deposition method, the primary deposition product obtained is subjected to a secondary deposition at 300-1000° C. by a vapor deposition method with the benzene-rich hydrocarbon gas described in step (1), and the obtained product is dried at 60-200° C. for 5-12 h to obtain a non-metallic porous carbon negative electrode material;

[0052] The non-metallic source gas includes any one of silane, phosphorus vapor, phosphine, phosphorus bromide, triphenylphosphine or alkane; the alkane includes any one of methane, ethane, propane or butane or a combination of at least two of them.

[0053] In a second aspect, the present invention further provides a non-metallic porous carbon negative electrode material, which is prepared according to the preparation method described in the first aspect.

[0054] As a preferred technical solution of the present invention, the non-metallic porous carbon material includes a silicon-carbon negative electrode material, a phosphorus-carbon negative electrode material or a carbon / carbon composite negative electrode material.

[0055] As a preferred technical solution of the present invention, the silicon-carbon negative electrode material includes porous carbon, silicon particles dispersed in the pores of the porous carbon, and a carbon coating layer coated on the surface of the porous carbon.

[0056] Preferably, the phosphorus-carbon negative electrode material comprises porous carbon, phosphorus particles dispersed in pores of the porous carbon, and a carbon coating layer coated on the surface of the porous carbon.

[0057] Preferably, the carbon / carbon composite negative electrode material comprises porous carbon, carbon particles dispersed in pores of the porous carbon, and a carbon coating layer coated on the surface of the porous carbon.

[0058] In a third aspect, the present invention also provides an application of a non-metallic porous carbon negative electrode material, wherein the non-metallic porous carbon negative electrode material prepared by the preparation method described in the first aspect, or the non-metallic porous carbon negative electrode material described in the second aspect, is applied to a sodium ion battery.

[0059] In a fourth aspect, the present invention also provides an application of a non-metallic porous carbon negative electrode material, wherein the non-metallic porous carbon negative electrode material prepared by the preparation method described in the first aspect, or the non-metallic porous carbon negative electrode material described in the second aspect is mixed with graphite and applied to a lithium-ion battery.

[0060] Preferably, the graphite includes natural graphite or artificial graphite.

[0061] Preferably, the mass ratio of the graphite to the non-metallic porous carbon negative electrode material is (0.05-10):1, for example, 0.05:1, 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0062] Compared with the prior art, the present invention has at least the following beneficial effects:

[0063] 1) The present invention utilizes hydrogen to activate the pyrolysis of carbon-containing raw materials to achieve continuous preparation of porous carbon and non-metallic porous carbon negative electrode materials, wherein hydrogen is used as a pore-forming agent, and steam generated when the carbon-containing raw materials themselves decompose at high temperatures can also be generated from the inside of the carbon-containing raw material skeleton as a pore-forming agent. The excess hydrogen generated in this process can be recycled into a mixture of hydrogen and argon and used again to activate the carbon-containing raw materials, and then recycled;

[0064] 2) The porous carbon prepared by the present invention has a uniform pore size distribution and a large specific surface area. At the same time, hydrogen activation can be used to efficiently remove oxygen, which is beneficial to the subsequent deposition of non-metals, avoiding safety issues caused by high oxygen content during the deposition of non-metals, and also avoiding the generation of other non-metal oxide impurities in the process;

[0065] 3) The benzene-rich oil hydrocarbon byproduct gas produced during the preparation of porous carbon in the present invention can be used as a coating raw material to coat the material, thereby achieving efficient utilization of carbon-containing raw materials and near-zero emissions of pollutants, avoiding the use of traditional raw materials such as acetylene for coating again, and the process is simple, easy to implement, and starts large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a process flow chart of preparing a non-metallic porous carbon negative electrode material according to Example 1 of the present invention;

[0067] Figure 2 is a BET adsorption-desorption curve diagram of the negative electrode powder prepared in Application Example 1 of the present invention;

[0068] Figure 3 This is the first cycle charge and discharge curve of the lithium ion battery prepared in Application Example 1 of the present invention;

[0069] Figure 4 This is the first cycle charge and discharge curve of the sodium ion battery prepared in Application Example 12 of the present invention. DETAILED DESCRIPTION

[0070] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0071] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0072] Example 1

[0073] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material. The process flow chart of the non-metallic porous carbon negative electrode material is as follows: Figure 1 As shown, the preparation method comprises the following steps:

[0074] (1) After washing bituminous coal with a particle size of less than 74 μm with hydrochloric acid and hydrofluoric acid, the coal is placed in a high-temperature tube furnace, and a mixed gas containing 5 vol% hydrogen and argon is introduced at a flow rate of 500 mL / min. The temperature is increased to 800°C at a heating rate of 0.05°C / min, and the target temperature is maintained for 2 h at a pressure of 2 MPa. The coal is naturally cooled to room temperature to obtain porous carbon and benzene-rich oil hydrocarbon gas, and the excess hydrogen is returned to the mixed gas;

[0075] (2) The porous carbon was subjected to a first deposition of silane at 500°C by a vapor deposition method, and then the first deposition product was subjected to a second deposition by a vapor deposition method using a benzene-rich hydrocarbon gas at 500°C, and then dried at 120°C for 8 hours and cooled to room temperature to obtain a silicon-carbon negative electrode material.

[0076] Example 2

[0077] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material, the preparation method comprising the following steps:

[0078] (1) placing bituminous coal with a particle size of less than 74 μm into a high-temperature tube furnace, introducing a mixed gas containing 5 vol% hydrogen and argon at a flow rate of 300 mL / min, heating to 800°C at a heating rate of 0.05°C / min, maintaining the temperature at the target temperature for 2 h, with a pressure of 2 MPa, and naturally cooling to room temperature to obtain porous carbon and benzene-rich oil hydrocarbon gas, and the excess hydrogen returns to the mixed gas;

[0079] (2) After washing the porous carbon with hydrochloric acid and hydrofluoric acid, the deashed porous carbon is subjected to a primary silane deposition at 500°C by a vapor phase deposition method. Subsequently, the primary deposition product is subjected to a secondary deposition at 500°C using a benzene-rich hydrocarbon gas by a vapor phase deposition method. The product is dried at 60°C for 12 hours and cooled to room temperature to obtain a silicon-carbon negative electrode material.

[0080] Example 3

[0081] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material, the preparation method comprising the following steps:

[0082] (1) After washing bituminous coal with a particle size of less than 74 μm with hydrochloric acid and hydrofluoric acid, the coal is placed in a high-temperature tube furnace, and a mixed gas containing 5 vol% hydrogen and argon is introduced at a flow rate of 500 mL / min. The temperature is increased to 700°C at a heating rate of 0.05°C / min, and the target temperature is maintained for 2 h at a pressure of 5 MPa. The coal is naturally cooled to room temperature to obtain porous carbon and benzene-rich oil hydrocarbon gas, and the excess hydrogen is returned to the mixed gas;

[0083] (2) The porous carbon was subjected to a first deposition of silane at 500°C by a vapor deposition method, and then the first deposition product was subjected to a second deposition by a vapor deposition method using a benzene-rich hydrocarbon gas at 500°C, and then dried at 200°C for 5 hours and cooled to room temperature to obtain a silicon-carbon negative electrode material.

[0084] Example 4

[0085] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material, the preparation method comprising the following steps:

[0086] (1) After washing bituminous coal with a particle size of less than 74 μm with hydrochloric acid and hydrofluoric acid, the coal is placed in a high-temperature tube furnace, and a mixed gas containing 5 vol% hydrogen and argon is introduced at a flow rate of 500 mL / min. The temperature is increased to 1000°C at a heating rate of 0.05°C / min, and the target temperature is maintained for 2 h at a pressure of 5 MPa. The coal is naturally cooled to room temperature to obtain porous carbon and benzene-rich oil hydrocarbon gas, and the excess hydrogen is returned to the mixed gas;

[0087] (2) Using a vapor phase deposition method, silane is deposited once on the porous carbon at 400°C, and then the primary deposition product is deposited twice at 800°C using a benzene-rich hydrocarbon gas using a vapor phase deposition method, and then dried at 180°C for 10 hours and cooled to room temperature to obtain a silicon-carbon negative electrode material.

[0088] Example 5

[0089] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material, the preparation method comprising the following steps:

[0090] (1) After washing walnut shells with a particle size of less than 74 μm with hydrochloric acid and hydrofluoric acid, the shells were placed in a high-temperature tube furnace, and a mixed gas containing 3 vol% hydrogen and argon was introduced at a flow rate of 500 mL / min. The temperature was increased to 900°C at a heating rate of 0.05°C / min, and the temperature was maintained at the target temperature for 2 h. The pressure was 2 MPa, and the shells were naturally cooled to room temperature to obtain porous carbon and benzene-rich oil hydrocarbon gas, and the excess hydrogen returned to the mixed gas;

[0091] (2) The porous carbon was subjected to a first deposition of silane at 420°C by a vapor deposition method, and then the first deposition product was subjected to a second deposition by a vapor deposition method using a benzene-rich hydrocarbon gas at 800°C, and then dried at 100°C for 9 hours and cooled to room temperature to obtain a silicon-carbon negative electrode material.

[0092] Example 6

[0093] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material, the preparation method comprising the following steps:

[0094] (1) Asphalt with a particle size of less than 74 μm is placed in a high-temperature tubular furnace, and a mixed gas containing 2 vol% hydrogen and argon is introduced at a flow rate of 100 mL / min, and the temperature is increased to 1000°C at a heating rate of 15°C / min. The mixture is kept at the target temperature for 1 h, the pressure is 10 MPa, and the mixture is naturally cooled to room temperature to obtain porous carbon and benzene-rich oil hydrocarbon gas, and the excess hydrogen returns to the mixed gas;

[0095] (2) After washing the porous carbon with hydrochloric acid and hydrofluoric acid, silane is deposited on the porous carbon once at 450°C by a vapor deposition method. Then, the primary deposition product is deposited again by a vapor deposition method using a benzene-rich hydrocarbon gas at 900°C. The product is dried at 150°C for 11 hours and cooled to room temperature to obtain a silicon-carbon negative electrode material.

[0096] Example 7

[0097] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material. The difference between the preparation method and Example 1 is that in step (2), phosphine is used to deposit porous carbon, and the remaining preparation methods and parameters are consistent with Example 1, and the prepared material is a phosphorus-carbon negative electrode material.

[0098] Example 8

[0099] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material. The difference between the preparation method and Example 1 is that in step (1), the activation temperature is 600° C., and the rest of the preparation method and parameters are consistent with Example 1.

[0100] Example 9

[0101] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material. The difference between the preparation method and Example 1 is that in step (1), the activation temperature is 1100° C., and the rest of the preparation method and parameters are consistent with Example 1.

[0102] Example 10

[0103] This embodiment provides a method for preparing a non-metallic porous carbon negative electrode material, the preparation method comprising the following steps:

[0104] (1) After washing walnut shells with a particle size of less than 74 μm with hydrochloric acid and hydrofluoric acid, the shells were placed in a high-temperature tube furnace, and a mixed gas containing 3 vol% hydrogen and argon was introduced at a flow rate of 500 mL / min. The temperature was increased to 900°C at a heating rate of 0.05°C / min, and the temperature was maintained at the target temperature for 2 h. The pressure was 2 MPa, and the shells were naturally cooled to room temperature to obtain porous carbon and benzene-rich oil hydrocarbon gas, and the excess hydrogen returned to the mixed gas;

[0105] (2) The porous carbon was subjected to a primary acetylene deposition at 450°C by a vapor deposition method, and then a secondary deposition was performed on the primary deposition product at 1000°C using a benzene-rich hydrocarbon gas by a vapor deposition method, and the product was dried at 80°C for 12 hours and cooled to room temperature to obtain a carbon / carbon composite negative electrode material.

[0106] Comparative Example 1

[0107] This comparative example provides a method for preparing a non-metallic porous carbon negative electrode material. The difference between the preparation method and Example 1 is that in step (1), the bituminous coal is activated in nitrogen, and the rest of the preparation method and parameters are consistent with Example 1.

[0108] Comparative Example 2

[0109] This comparative example provides a method for preparing a non-metallic porous carbon negative electrode material. The difference between the preparation method and Example 1 is that the step of deashing the bituminous coal is omitted, and the rest of the preparation method and parameters are consistent with Example 1.

[0110] Application Examples 1 to 9 and Comparative Application Examples 1 to 2

[0111] The non-metallic porous carbon negative electrode materials prepared in Examples 1 to 9 and Comparative Examples 1 to 2 were mixed with graphite to obtain negative electrode powders, and then negative electrode sheets were prepared. Lithium sheets were used as positive electrode sheets, and the electrolyte was EC+DMC. Lithium-ion batteries were assembled, corresponding to Application Examples 1 to 9 and Comparative Application Examples 1 to 2, respectively.

[0112] Application Example 10

[0113] The non-metallic porous carbon negative electrode material prepared in Example 1 was used to prepare a negative electrode sheet, a sodium sheet was used as a positive electrode sheet, and DME was used as an electrolyte to assemble a sodium ion battery.

[0114] Application Example 11

[0115] The non-metallic porous carbon negative electrode material prepared in Example 7 was used to prepare a negative electrode sheet, a sodium sheet was used as a positive electrode sheet, and DME was used as an electrolyte to assemble a sodium ion battery.

[0116] Application Example 12

[0117] The non-metallic porous carbon negative electrode material prepared in Example 10 was used to prepare a negative electrode sheet, a sodium sheet was used as a positive electrode sheet, and DME was used as an electrolyte to assemble a sodium ion battery.

[0118] Test Method

[0119] 1) The porous carbon prepared in step (1) of Examples 1 to 10 and Comparative Examples 1 to 2 was tested for specific surface area using a nitrogen physical adsorption and desorption instrument. The specific test results are shown in Table 1;

[0120] 2) The negative electrode powders prepared in Application Examples 1 to 9 and Application Examples 1 to 2 were tested for specific surface area using a nitrogen physical adsorption and desorption instrument. The specific test results are shown in Table 2;

[0121] 3) The lithium ion batteries prepared in Application Examples 1 to 9 and Application Examples 1 to 2 were subjected to charge and discharge tests at a rate of 1C within a voltage range of 2.5 to 4.2 V. The specific test results are shown in Table 2;

[0122] 4) The non-metallic porous carbon negative electrode materials prepared in Example 1, Example 7 and Example 10 were tested for specific surface area using a nitrogen physical adsorption and desorption instrument. The specific test results are shown in Table 3;

[0123] 5) The sodium ion batteries prepared in Application Examples 10 to 12 were subjected to charge and discharge tests at a rate of 1C within a voltage range of 2.5 to 4.2 V. The specific test results are shown in Table 3.

[0124] Figure 2 The BET adsorption-desorption curve of the negative electrode powder prepared in Application Example 1 is shown. It can be seen from the figure that the specific surface area of ​​the negative electrode powder reaches 16.6 m 2 / g.

[0125] Figure 3 The first cycle charge and discharge curve of the lithium-ion battery prepared in Application Example 1 is shown. It can be seen from the figure that the charge specific capacity can reach 558 mAh / g.

[0126] Table 1

[0127] project <![CDATA[Specific surface area of porous carbon (m 2 / g)]]> Example 1 251.5 Example 2 252.4 Example 3 248.8 Example 4 250.6 Example 5 251 Example 6 287.8 Example 7 252.1 Example 8 222.9 Example 9 223.2 Example 10 260.0 Comparative Example 1 201.6 Comparative Example 2 220

[0128] Table 2

[0129]

[0130] Figure 4 The first cycle charge and discharge curve of the sodium ion battery prepared in Application Example 12 is shown. It can be seen from the figure that the charge specific capacity can reach 360mAh / g.

[0131] Table 3

[0132]

[0133] The test results show that:

[0134] (1) It can be seen from Examples 1 to 10 in Table 1 and Application Examples 1 to 9 in Table 2 that the present invention activates the carbon-containing raw material with hydrogen to obtain porous carbon and benzene-rich hydrocarbon gas, and then uses the porous carbon as a carrier to deposit silicon particles, phosphorus particles or carbon particles, so that the particles enter the pores of the porous carbon. The presence of the porous carbon provides space for the volume expansion of silicon, phosphorus and carbon during battery operation, thereby alleviating the problem of negative electrode volume expansion. In addition, the benzene-rich hydrocarbon gas is used as a by-product as a raw material for carbon coating, and the by-product is fully utilized. The presence of the carbon coating layer further plays a buffering role, thereby improving the overall conductivity of the material. Specifically, the prepared porous carbon has a specific surface area of ​​222 m 2 / g or more, the specific capacity of the negative electrode powder assembled lithium-ion battery is above 440mAh / g, and the initial capacity retention rate is above 90%;

[0135] (2) It can be seen from Example 1 and Examples 8 to 9 in Table 1 and Application Examples 1 and Application Examples 8 to 9 in Table 2 that the present invention can better achieve the effect of hydrogen activation by further adjusting the activation temperature to 700 to 1000° C., and the prepared porous carbon has a higher specific surface area. The specific capacity and initial capacity retention rate of the negative electrode material obtained after two depositions are both better;

[0136] (3) It can be seen from Example 1 and Comparative Example 1 in Table 1 that the negative electrode material with better performance can be prepared only when the activation is carried out in hydrogen. At the same time, hydrogen also acts as a pore-forming agent to achieve the coordinated production of porous carbon and benzene-rich oil hydrocarbon gas. In addition, the presence of hydrogen can also achieve the effect of efficient deoxidation, avoiding the safety problems caused by the high oxygen content in the process of depositing non-metallic materials, and also avoiding the generation of other non-metallic oxide impurities in the process. Nitrogen cannot play the role that the corresponding hydrogen can produce;

[0137] (4) It can be seen from Example 1 and Comparative Example 2 in Table 1, and Application Example 1 and Comparative Application Example 2 in Table 2 that when the deashing and purification step is omitted in the present invention, the impurities inside the carbonaceous raw material will affect the conductivity, ion transport and mass activity, thereby reducing the specific surface area of ​​the porous carbon, affecting the specific capacity of the negative electrode material and the initial capacity retention rate;

[0138] (5) It can be seen from Application Examples 10 to 12 in Table 3 that the silicon-carbon negative electrode material, phosphorus-carbon negative electrode material and carbon / carbon negative electrode material prepared by the present invention all exhibit relatively high negative electrode specific capacity and initial capacity retention rate after being assembled into sodium ion batteries, and also have relatively good electrochemical performance when applied in sodium ion batteries.

[0139] In summary, the present invention realizes the continuous preparation of porous carbon and non-metallic porous carbon negative electrode materials by hydrogen activation of carbon-containing raw materials. Hydrogen activation allows efficient deoxidation of carbon-containing materials, avoiding the generation of other non-metallic oxide impurities during the deposition of non-metals. The surplus hydrogen generated during the activation process can be recycled to the hydrogen activation step for repeated use. The gaseous benzene-rich oil hydrocarbon byproducts generated during the hydrogen activation of carbon-containing materials can also be further carbon-coated to achieve efficient utilization of carbon-containing resources.

[0140] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a non-metallic porous carbon negative electrode material, characterized in that: The preparation method comprises the following steps: (1) activating a carbonaceous raw material in a hydrogen-containing mixed gas to obtain porous carbon and benzene-rich oil hydrocarbon gas; (2) mixing the non-metallic source gas with the porous carbon described in step (1) to perform a primary deposition, and mixing the primary deposition product obtained with the benzene-rich hydrocarbon gas described in step (1) to perform a secondary deposition to obtain a non-metallic porous carbon negative electrode material; Wherein, the benzene-rich hydrocarbon gas in step (1) includes any one or a combination of at least two of alkanes, aromatic hydrocarbons, alkenes or alkynes; The carbon-containing raw material in step (1) is further deashed before use, or the porous carbon in step (1) is deashed before step (2).

2. The preparation method according to claim 1, characterized in that: The carbon-containing raw material in step (1) includes any one of coal, biomass, asphalt or petroleum coke, or a combination of at least two thereof; Preferably, the coal comprises medium and low rank coal; Preferably, the low- to medium-rank coal includes any one of bituminous coal, sub-bituminous coal or lignite, or a combination of at least two thereof; Preferably, the alkane includes any one of methane, ethane or propane, or a combination of at least two thereof; Preferably, the aromatic hydrocarbon includes any one or a combination of at least two of benzene, naphthalene, phenanthrene, pyrene, toluene or ethylbenzene; Preferably, the olefin comprises propylene or ethylene; Preferably, the alkyne comprises acetylene; Preferably, the hydrogen-containing mixed gas in step (1) comprises a mixed gas of hydrogen and argon; Preferably, the content of hydrogen in the mixture of hydrogen and argon is 0 to 5 vol%, and is not 0; Preferably, the deliming comprises mechanical deliming or chemical deliming.

3. The preparation method according to claim 1 or 2, characterized in that: The activation temperature of step (1) is 700-1000° C. Preferably, the activation heating rate in step (1) is 0.05 to 15°C / min; Preferably, the activation holding time in step (1) is 1 to 5 hours; Preferably, the activation pressure in step (1) is 0.1-10 MPa.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The non-metallic source gas in step (2) includes any one of silane, phosphorus vapor, phosphine, phosphorus bromide, triphenylphosphine or alkane; Preferably, the alkane includes any one of methane, ethane, propane or butane, or a combination of at least two thereof; Preferably, the primary deposition method in step (2) comprises a vapor deposition method; Preferably, the temperature of the primary deposition in step (2) is 300-800° C. Preferably, the secondary deposition method in step (2) comprises a vapor deposition method; Preferably, the temperature of the secondary deposition in step (2) is 300-1000°C.

5. The preparation method according to claim 1, characterized in that: The preparation method comprises the following steps: (1) activating the deashed carbonaceous raw material in a mixture of hydrogen and argon at a rate of 0.05 to 15°C / min to 700 to 1000°C, keeping the temperature for 1 to 5 hours, and activating at an activation pressure of 0.1 to 10 MPa to obtain porous carbon and benzene-rich oil hydrocarbon gas; Wherein, in the mixed gas of hydrogen and argon, the content of hydrogen is 0-5 vol%, and is not 0; the gas flow rate of the mixed gas containing hydrogen and argon is 100-500 mL / min; the carbon-containing raw material includes any one of coal, biomass, asphalt or petroleum coke, or a combination of at least two; the deashing includes mechanical deashing or chemical deashing; the coal includes medium and low rank coal; the medium and low rank coal includes any one of bituminous coal, sub-bituminous coal or lignite, or a combination of at least two; the benzene-rich oil hydrocarbon gas includes any one of alkanes, aromatic hydrocarbons, olefins or alkynes, or a combination of at least two; the alkane includes any one of methane, ethane or propane, or a combination of at least two; the aromatic hydrocarbon includes any one of benzene, naphthalene, phenanthrene, pyrene, toluene or ethylbenzene, or a combination of at least two; the olefin includes propylene or ethylene; the alkyne includes acetylene; (2) The non-metallic source gas and the porous carbon described in step (1) are subjected to a primary deposition at 300-800° C. by a vapor deposition method, the primary deposition product obtained is subjected to a secondary deposition at 300-1000° C. by a vapor deposition method with the benzene-rich hydrocarbon gas described in step (1), and the obtained product is dried at 60-200° C. for 5-12 h to obtain a non-metallic porous carbon negative electrode material; The non-metallic source gas includes any one of silane, phosphorus vapor, phosphine, phosphorus bromide, triphenylphosphine or alkane; the alkane includes any one of methane, ethane, propane or butane or a combination of at least two thereof.

6. A non-metallic porous carbon negative electrode material, characterized in that: The non-metallic porous carbon negative electrode material is prepared according to the preparation method according to any one of claims 1-5.

7. The non-metallic porous carbon negative electrode material according to claim 6, characterized in that: The non-metallic porous carbon negative electrode material includes a silicon-carbon negative electrode material, a phosphorus-carbon negative electrode material or a carbon / carbon composite negative electrode material.

8. The non-metallic porous carbon negative electrode material according to claim 7, characterized in that: The silicon-carbon negative electrode material comprises porous carbon, silicon particles dispersed in the pores of the porous carbon, and a carbon coating layer coated on the surface of the porous carbon; Preferably, the phosphorus-carbon negative electrode material comprises porous carbon, phosphorus particles dispersed in the pores of the porous carbon, and a carbon coating layer coated on the surface of the porous carbon; Preferably, the carbon / carbon composite negative electrode material comprises porous carbon, carbon particles dispersed in pores of the porous carbon, and a carbon coating layer coated on the surface of the porous carbon.

9. An application of a non-metallic porous carbon negative electrode material, characterized in that: The non-metallic porous carbon negative electrode material prepared by the preparation method according to any one of claims 1 to 5, or the non-metallic porous carbon negative electrode material according to any one of claims 6 to 8, is applied to a sodium ion battery.

10. An application of a non-metallic porous carbon negative electrode material, characterized in that: The non-metallic porous carbon negative electrode material prepared by the preparation method according to any one of claims 1 to 5, or the non-metallic porous carbon negative electrode material according to any one of claims 6 to 8 is mixed with graphite and applied to a lithium-ion battery.

Images