Element co-doped carbon material and preparation method and application thereof

Abstract

The invention belongs to the technical field of new energy materials, and particularly relates to an element co-doped carbon material and a preparation method and application thereof. When the nitrogen, oxygen, sulfur and iodine co-doped expanded-layer carbon material prepared according to the method is used as a host material of a hard carbon negative electrode and a high-capacity silicon carbon negative electrode of an alkali metal ion battery, rich elements such as nitrogen, oxygen, sulfur and iodine can be used as active sites of alkali metal ions, transportation of the alkali metal ions in electrode particles is promoted, and the service life of the electrode particles is prolonged. The iodine element participates in forming the negative electrode SEI, so that the ionic conductivity and the structural stability of the SEI layer can be improved, and the capacity, the cycle performance and the rate performance of the material are further improved; when being used as a host material of a sulfur positive electrode of an alkali metal sulfur battery, elements such as nitrogen, oxygen, sulfur, iodine and the like can be combined with alkali metal ions to promote ionic conductivity, adsorb and catalyze conversion of alkali metal polysulfide and catalyze solid-phase conversion between lithium sulfide and elemental sulfur in a solid-state lithium-sulfur battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new energy materials, and particularly relates to an element co-doped carbon material and a preparation method and application thereof. BACKGROUND

[0002] Carbonaceous materials are widely used in secondary batteries. For example, graphite, hard carbon, soft carbon, etc. are negative active materials of lithium batteries or sodium batteries, conductive carbon black (SP), carbon nanotubes, graphene, carbon fibers, etc. are commonly used conductive agents in electrodes, and microporous carbon, mesoporous carbon and macroporous carbon can be used as carbonaceous matrix of sulfur-carbon positive electrode and vapor-deposited silicon negative electrode. With the expansion of application scenarios, pure carbonaceous materials and conventional pore structures have gradually failed to meet the demand of secondary batteries for electrical performance, and heteroatom doping and pore structure / carbon layer spacing regulation have become an important development direction for the multifunctionalization of carbonaceous materials.

[0003] The carbon source for preparing carbonaceous materials mainly includes pitch-based carbon source, biomass and organic high polymer, etc. Among them, the pitch-based carbon source is divided into coal tar pitch and petroleum pitch. This type of carbon precursor is widely sourced and low in price, but has high volatile matter and environmental problems, and the components are uncontrollable. Biomass includes walnut shell, coconut shell, softwood, kelp, regenerated cotton, etc. This type of carbon precursor has low cost, but the consistency of the product is poor and the carbon residue rate is low. Organic high polymer includes resin (such as phenolic resin, epoxy resin, polyfurfuryl alcohol resin, etc.) and other high polymer, such as polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), etc. The carbon material prepared from this type of carbon precursor has good consistency and high carbon residue rate. In summary, organic high polymer has higher designability and controllability, and is a technical route that needs to be focused on. At present, in the process of preparing carbon material using organic high polymer in the prior art, there are problems such as easy carbon loss, difficulty in regulating carbon layer spacing, ineffective doping of heteroatoms, and insignificant improvement in specific capacity and cycle stability of the obtained carbon material. SUMMARY

[0004] One of the purposes of the present application is to provide a preparation method of an element co-doped carbon material to solve the problems in the prior art such as easy carbon loss, difficulty in regulating carbon layer spacing, ineffective doping of heteroatoms, and insignificant improvement in specific capacity and cycle stability of the obtained carbon material. The second purpose is to provide an element co-doped carbon material. The third purpose is to provide an application of the element co-doped carbon material.

[0005] In order to achieve the above purposes, the technical solutions adopted by the present application are as follows:

[0006] According to one aspect of the present application, a preparation method of an element co-doped carbon material is provided, which comprises the following steps:

[0007] S1, mixing phenylenediamine, iodine-containing oxidizing agent and sulfuration agent, and carrying out the first reaction at 50-279°C in an oxygen-free environment;

[0008] S2, raising the temperature to 280-420°C to carry out the second reaction;

[0009] S3, raising the temperature to 500-2000°C to carry out the third reaction.

[0010] According to the above technical means, the present application takes phenylenediamine as raw material, rich in nitrogen element, uses the reducing property and iodization property of aniline functional group, realizes the oxidative polymerization and iodization doping of phenylenediamine in the presence of iodine-containing oxidant through the control of the first reaction temperature, obtains the intermediate product rich in nitrogen, oxygen and iodine in one step, the process is simple, and the content of nitrogen, oxygen and iodine is controllable; the raw material also has a sulfidizing agent at the same time, which can occur pre-sulfurization reaction at the second reaction temperature to obtain nitrogen, oxygen and iodine co-doped sulfidized polyphenylenediamine, the structure unit of the intermediate product rich in nitrogen, oxygen and iodine is 2,3-diamino phenazine (benzophenazine), the structure unit is connected through an N atom to form a long chain structure, in the pre-sulfurization process, the C-H on both sides of the benzene ring in the long chain structure is dehydrogenated and sulfidized to generate a sulfur branch, so the long chain skeleton is connected through the C-Sx-C (x≥1) branch, compared with the pre-oxidation method, the carbon loss is reduced. This is because: the traditional pre-oxidation process of carbon material is to expose the carbon precursor to an oxygen atmosphere above 300 DEG C, the precursor reacts with oxygen to introduce oxygen-containing functional groups (such as ester, ether, carboxylic acid) and form 3D cross-linked structure, which prevents the ordered arrangement of carbon layer and graphitization, and at higher temperature, the oxygen-containing functional groups escape to form a void microstructure. Traditional pre-oxidation: ①Oxygen is more reactive and can react with multiple sites of the precursor, the position and amount of oxygen cross-linking are more, which is difficult to control; ②The pre-oxidation reaction position and degree are difficult to control because the precursor is continuously exposed to a large excess of oxygen, and CO2 is generated during the pre-oxidation process, causing carbon loss and reducing carbon yield; ③The pre-oxidation temperature is higher, the reaction sites are more and the degree is greater, which is difficult to control, and more carbon is lost. The pre-sulfurization process adopted by the present application: ①The reaction activity of sulfur is lower than that of oxygen, the reaction site is selective, the reaction site is fixed and controllable, and only the C-H site on the benzene ring reacts to generate the C-Sx-C functional group, without generating a large amount of different types of sulfur-containing functional groups; ②In the pre-sulfurization process, the ratio of the precursor to sulfur can be adjusted, and the pre-sulfurization degree (the length of the cross-linked sulfur chain) can be controlled according to the stoichiometric ratio and the closed state of the reaction container; ③Pre-sulfurization does not cause carbon loss. In the third reaction process, carbonization is realized, the C-Sx-C (x≥1) branch generates desulfurization reaction to generate a short sulfur chain, the main chain generates denitrification, deoxidation and deiodination reaction, and the partial removal of heteroatoms is conducive to the formation of local micropores, which can provide accommodation space for high-capacity active materials, provide abundant catalytic sites for interface reaction, and provide active cavities for alkali metal deposition-stripping, realizing the multifunctionalization of carbon materials. The iodine element in the carbon material can participate in the formation of negative electrode SEI, can improve the ion conductivity and structural stability of the SEI layer, and then improve the cycle and rate performance of the material. In addition, the method also has the advantages of simple synthesis method, high product consistency and scaleable production.The present application can obtain the highest polymerization degree, the intermediate product with moderate oxidation and iodination degree by limiting the first reaction temperature. The product can be avoided from being over-oxidized, over-iodinated or insufficiently oxidized and iodinated in the subsequent steps by controlling the second reaction temperature and the third reaction temperature, thereby avoiding the problems of deviating from the content of heteroatoms and insufficient carbon content, and affecting the electrical properties of the material.

[0011] In some alternative embodiments, in S1, the time of the first reaction is 1-2880 minutes;

[0012] In some alternative embodiments, in S2, the time of the second reaction is 30-4320 minutes;

[0013] In some alternative embodiments, in S3, the time of the third reaction is 30-4320 minutes.

[0014] In some alternative embodiments, in S1, the molar ratio of the phenylenediamine, iodine-containing oxidizing agent and sulfurizing agent is 1:0.5-5:3-20. For example, the molar ratio of the phenylenediamine, iodine-containing oxidizing agent and sulfurizing agent can be 1:0.5:20, 1:1:17, 1:2:15, 1:3:10, 1:4:8, 1:5:3, or within a range consisting of any of the above values.

[0015] According to the above technical means, the content of doping elements can be controlled by limiting the molar ratio of raw materials. In addition, the C-H dehydrogenation sulfuration rate and the length of sulfur side chains can be controlled by the mixing molar ratio of the sulfurizing agent and the phenylenediamine, the second reaction temperature, the second reaction time, and the closed state of the reaction container, so as to realize the controllable doping of sulfur elements. The amount of nitrogen, oxygen, sulfur and iodine elements can be controlled by the third reaction temperature, the third reaction time, and the closed state of the reaction container, so as to realize the control of the electrical properties of the material.

[0016] In some alternative embodiments, the phenylenediamine includes at least one of o-phenylenediamine, p-phenylenediamine, and m-phenylenediamine;

[0017] In some alternative embodiments, the iodine-containing oxidizing agent includes at least one of sodium periodate, metaperiodic acid, orthoperiodic acid, lithium periodate, and potassium periodate;

[0018] In some alternative embodiments, the sulfurizing agent includes at least one of elemental sulfur, sulfur dioxide, sulfur trioxide, metal polysulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, dithiohexanolactam, and dithiodimorpholine.

[0019] In some alternative embodiments, in S1, the oxygen-free environment is a vacuum, nitrogen or inert gas environment;

[0020] In some alternative embodiments, the phenylenediamine is o-phenylenediamine;

[0021] and / or the sulfurizing agent is elemental sulfur.

[0022] According to the above technical means, the raw materials are preferably selected, and the raw materials have the advantages of low cost, sustainable resources, and scalable production.

[0023] In some optional embodiments, in S1, the mixing method of the phenylenediamine, the iodine-containing oxidizing agent, and the sulfurizing agent is stirring, grinding, ball milling, sand milling, including dry mixing and wet mixing with a liquid medium. If wet mixing is performed, the liquid medium is any one or more of water, ethanol, isopropanol, N,N-dimethylformamide, benzene, toluene, an acid solution (phosphoric acid, boric acid, nitric acid, etc.), an alkali solution (sodium hydroxide solution, potassium hydroxide solution, etc.), a salt solution (sodium chloride, potassium chloride, ammonium chloride, etc.). The material after wet mixing is dried at -20°C to 200°C, and the drying method includes vacuum or air drying, freeze drying, spray drying, electrospinning, etc.

[0024] According to another aspect of the present application, an element co-doped carbon material is provided, which is prepared by the above preparation method.

[0025] According to the above technical means, the nitrogen, oxygen, sulfur, and iodine co-doped expanded carbon material prepared by the method of the present application, when used as a hard carbon negative electrode and a high-capacity silicon-carbon negative electrode host material for alkali metal ion batteries, the rich nitrogen, oxygen, sulfur, and iodine elements can act as active sites for alkali metal ions. These elements are more Li + bonding than C + When Li + diffuses inside the carbon material, it will quickly transport on the channels formed by these elements, promoting the transport of alkali metal ions inside the electrode particles, thereby improving the rate performance. At the same time, nitrogen, oxygen, sulfur, and iodine elements on the surface of the carbon material can participate in the formation of SEI components with good ionic conductivity, such as Li3N and LiI, promoting the diffusion of lithium ions to the inside, thus facilitating the release of internal material capacity and improving the capacity performance. Iodine elements participate in the formation of negative electrode SEI components, which are inorganic products with strong rigidity, which can improve the ionic conductivity and structural stability of the SEI layer, thereby improving the cycle performance of the material. When used as a sulfur positive electrode host material for alkali metal sulfur batteries, nitrogen, oxygen, sulfur, and iodine elements can bind to alkali metal ions, promote ionic conductivity, adsorb and catalyze the conversion of alkali metal polysulfides, catalyze the solid-phase conversion between lithium sulfide and elemental sulfur in solid-state lithium-sulfur batteries, and improve the capacity and cycle performance of alkali metal sulfur batteries. As described above, the carbon material of the present application is rich in N, O, S, and I elements, which have a greater bonding energy than Li +The binding energy of lithium polysulfide is higher than that of carbon, so that the lithium polysulfide can be adsorbed on the surface of the carbon material, avoiding a large amount of dissolution in the electrolyte to cause loss of active material, and the catalytic conversion of the heteroatom, especially I, to the lithium polysulfide is strong, which can accelerate the chemical reaction process, and the products are uniformly distributed to avoid accumulation inactivation and large polarization. In addition, the carbon material provided in the application has rich pores, which can accommodate more elemental sulfur and physically adsorb lithium polysulfide, and the above-mentioned effects can effectively improve the capacity and cycle performance of the alkali metal-sulfur battery.

[0026] According to another aspect of the application, an alkali metal ion battery is provided, comprising the above-mentioned element co-doped carbon material.

[0027] In some optional embodiments, the element co-doped carbon material is used as a negative active material.

[0028] Alternatively, the element co-doped carbon material is used as a host material, and after depositing silicon, it is used as a negative active material.

[0029] According to another aspect of the application, an alkali metal-sulfur battery is provided, comprising the above-mentioned element co-doped carbon material; the element co-doped carbon material is used as a host material, and the host material is loaded with a sulfur-containing guest material.

[0030] Optionally, the sulfur-containing guest material comprises at least one of elemental sulfur, lithium sulfide, sodium sulfide, potassium sulfide, lithium polysulfide, sodium polysulfide and potassium polysulfide.

[0031] In some optional embodiments, the alkali metal-sulfur battery includes but is not limited to a lithium-sulfur battery.

[0032] According to another aspect of the application, an electric device is provided, comprising the above-mentioned alkali metal ion battery or the above-mentioned alkali metal-sulfur battery.

[0033] The electric device provided in the application has the same advantages as the above-mentioned battery, which will not be repeated here.

[0034] Advantages of the application:

[0035] (1) The preparation method of the element co-doped carbon material provided in the application uses phenylenediamine as a raw material, is rich in nitrogen elements, utilizes the reducing property and iodizing property of the aniline functional group, realizes the oxidative polymerization and iodizing doping of phenylenediamine in the presence of an iodine-containing oxidizing agent by controlling the first reaction temperature, obtains an intermediate product rich in nitrogen, oxygen and iodine in one step, the process is simple, and the contents of nitrogen, oxygen and iodine are controllable; the raw material also has a sulfidizing agent at the same time, and a pre-sulfidation reaction can occur at the second reaction temperature to obtain nitrogen, oxygen and iodine co-doped sulfidized polyphenylenediamine, the structural unit of the intermediate product rich in nitrogen, oxygen and iodine is 2,3-diaminophenazine (benzophenazine), the structural unit is connected through an N atom to form a long chain structure, in the pre-sulfidation process, C-H on both sides of the benzene ring in the long chain structure is dehydrogenated and sulfidized to generate a sulfur branch, so the long chain skeletons are connected through C-Sx-C (x is greater than or equal to 1) branches, compared with the pre-oxidation method, carbon loss is reduced. In the third reaction process, carbonization is realized, at the same time, C-Sx-C (x is greater than or equal to 1) branches are de-sulfurized to generate short sulfur chains, the main chain is de-nitrogenated, de-oxygenated and de-iodinated, and partial removal of heteroatoms is conducive to the formation of local micropores, rich pore structures can provide accommodation space for high-capacity active materials, provide rich catalytic sites for interface reactions, and provide active cavities for alkali metal deposition-stripping, realizing the multifunctionalization of the carbon material. The iodine element in the carbon material can participate in the formation of a negative electrode SEI, can improve the ionic conductivity and structural stability of the SEI layer, and then improve the cycle and rate performance of the material. In addition, the method also has the advantages of simple synthesis method, high product consistency and scalable production. The application can obtain the highest polymerization degree, an intermediate product with moderate oxidation and iodization degree by limiting the first reaction temperature, and by controlling the second reaction temperature and the third reaction temperature, the problems of over-oxidation, over-iodization or insufficient oxidation and iodization in the subsequent steps can be avoided, thereby affecting the electrical properties of the material.

[0036] (2) The preparation method of the element co-doped carbon material provided in the application can realize the regulation of the content of the doping elements by limiting the molar ratio between the raw materials. In addition, the C-H dehydrogenation sulfidation rate and the length of the sulfur branch can be controlled by the mixing molar ratio of the sulfidizing agent and phenylenediamine, the second reaction temperature, the second reaction time and the closed state of the reaction container, the controllable doping of the sulfur element is realized, and the amount of nitrogen, oxygen, sulfur and iodine elements is regulated by regulating the third reaction temperature, the third reaction time and the closedness of the reaction container, thereby realizing the regulation of the electrical properties of the material.

[0037] (3) The preparation method of the element co-doped carbon material provided in the application also has the advantages of low cost of raw materials, sustainable resources and scalable production by optimizing the raw materials.

[0038] (4) The element co-doped carbon material provided in the present application is a nitrogen, oxygen, sulfur and iodine co-doped expanded carbon material prepared according to the method described above. When used as a hard carbon negative electrode and a high-capacity silicon-carbon negative electrode host material of an alkali metal ion battery, the rich nitrogen, oxygen, sulfur and iodine elements can act as active sites for alkali metal ions. These elements have a greater affinity for Li than C + , and a greater binding energy. Therefore, when Li + diffuses inside the carbon material, it will quickly transport through the channels formed by these elements, promoting the transport of alkali metal ions inside the electrode particles, thereby improving the rate performance. At the same time, the nitrogen, oxygen, sulfur and iodine elements on the surface of the carbon material can participate in the formation of SEI components with good ionic conductivity, such as Li3N and LiI, promoting the diffusion of lithium ions into the interior, thus facilitating the release of internal material capacity and improving the capacity performance. The iodine element participates in the formation of negative electrode SEI components, which are inorganic products with strong rigidity, which can improve the ionic conductivity and structural stability of the SEI layer, thereby improving the cycle performance of the material. When used as a sulfur positive electrode host material of an alkali metal-sulfur battery, the nitrogen, oxygen, sulfur and iodine elements can bind to alkali metal ions, promote ionic conductivity, adsorb and catalyze the conversion of alkali metal polysulfides, catalyze the solid-phase conversion between lithium sulfide and elemental sulfur in solid-state lithium-sulfur batteries, and improve the capacity and cycle performance of the alkali metal-sulfur battery. As described above, the carbon material of the present application is rich in N, O, S and I elements. The binding energy of these elements to Li + and lithium polysulfide is higher than that of carbon, which can adsorb lithium polysulfide on the surface of the carbon material, avoid the loss of active material caused by a large amount of dissolution in the electrolyte, and the catalytic conversion of the heteroatoms, especially I, to lithium polysulfide is strong, which can accelerate the chemical reaction process, the products are uniformly distributed, and the deactivation and polarization are avoided. In addition, the carbon material provided in the present application has abundant pores, which can accommodate more elemental sulfur and physically adsorb lithium polysulfide. The above effects can effectively improve the capacity and cycle performance of the alkali metal-sulfur battery.

[0039] (5) The electric device provided in the present application has the same advantages as the above-mentioned battery because it uses the alkali metal ion battery or alkali metal-sulfur battery provided in the present application. Details are not repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the description of the specific embodiments or prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0041] Figure 1 A scanning electron microscope (SEM) image of the intermediate product CNOI119-200 obtained in Example 1 of the present application;

[0042] Figure 2 SEM image of the intermediate product CNOSI119-400 obtained in Example 1 of the present application;

[0043] Figure 3 XRD pattern of the intermediate products CNOI119-200 and CNOSI119-400 obtained in Example 1 of the present application;

[0044] Figure 4 Electrochemical performance of CNOSI119-700 obtained in Example 1 of the present application when applied as a hard carbon negative electrode;

[0045] Figure 5 Electrochemical performance of CNOSI1420-600 obtained in Example 2 of the present application when applied in a lithium-sulfur battery;

[0046] Figure 6 Electrochemical performance of CNOSI1420-600 obtained in Example 2 of the present application when applied in a silicon-carbon negative electrode of a lithium-ion battery. DETAILED DESCRIPTION

[0047] The following examples are provided to better enable those skilled in the art to make and use the application, and are not intended to be limiting of the scope of the application, merely exemplifying the content of the application. Any product obtained by any combination of the features of the application with features of other prior art patents or patent applications, as well as any product obtained by a combination of the application with further modification, are to be construed to fall within the scope of the application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the use of the terms "including," "comprising," "having" and variations thereof herein is meant to encompass the inclusion of the recited elements but not the exclusion of others not recited.

[0049] In the description of embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0050] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive or alternative embodiments. It is expressly understood that the described embodiments are merely examples from a whole class of comparable embodiments which those skilled in the art will readily appreciate.

[0051] The ranges disclosed herein are intended to be "open" ranges, i.e., the upper and lower limits of the range are not included. The ranges are also intended to include any and all sub-ranges of the range, i.e., each number between (and including) the upper and lower limits of the range. For example, a range of "0-5" is intended to include any number between (and including) 0 and 5, such as 1, 2, 3, 4, etc. Also, a range of "0-5" is intended to include the range from (and including) -0 to (and including) 5, -1 to 5, 0 to 5, -2 to 5, -3 to 5, -4 to 5, -5 to 5, -5 to 2, -5 to 1, -5 to 0, etc.

[0052] In the description of the embodiments of the present application, the term "and / or" is only a kind of description of the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the three cases of A existing alone, A and B existing together, and B existing alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0053] In the description of the embodiments of the present application, the term "at least one" refers to one or more than two (including two).

[0054] If there is no special description, all the steps of the present application can be performed in sequence or randomly, and the preferred is performed in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0055] The specific experimental steps or conditions not mentioned in the embodiments can be performed according to the conventional experimental steps described in the literature in the art or the operation or conditions. The reagents or instruments not mentioned by the manufacturer are all conventional reagent products that can be obtained by market purchase.

[0056] As described in the background art, the preparation method of the element-doped carbon material in the prior art is easy to cause carbon loss, the carbon layer spacing is difficult to control, the heteroatoms cannot be effectively doped, and the specific capacity and cycle stability of the obtained carbon material are not significantly improved. In order to solve these problems, the present application provides the following technical solutions.

[0057] According to an aspect of the present application, a method for preparing an element co-doped carbon material is provided, comprising the following steps:

[0058] S1, mixing phenylenediamine, iodine-containing oxidizing agent and sulfuration agent, and performing a first reaction at 50-279°C in an oxygen-free environment;

[0059] S2, increasing the temperature to 280-420°C to perform a second reaction;

[0060] S3, increasing the temperature to 500-2000°C to perform a third reaction.

[0061] For example, the temperature of the first reaction can be 50°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, 230°C, 250°C, 279°C, or within a range defined by any of the above values; the temperature of the second reaction can be 280°C, 300°C, 330°C, 350°C, 370°C, 390°C, 400°C, 420°C, or within a range defined by any of the above values; the temperature of the third reaction can be 500°C, 700°C, 900°C, 1000°C, 1200°C, 1400°C, 1500°C, 1700°C, 1900°C, 2000°C, or within a range defined by any of the above values.

[0062] According to the above technical means, the present application takes phenylenediamine as raw material, rich in nitrogen element, uses the reducing property and iodization property of aniline functional group, realizes the oxidative polymerization and iodization doping of phenylenediamine in the presence of iodine-containing oxidant through the control of the first reaction temperature, obtains the intermediate product rich in nitrogen, oxygen and iodine in one step, the process is simple, and the content of nitrogen, oxygen and iodine is controllable; the raw material also has a sulfidizing agent at the same time, which can occur pre-sulfurization reaction at the second reaction temperature to obtain nitrogen, oxygen and iodine co-doped sulfidized polyphenylenediamine, the structure unit of the intermediate product rich in nitrogen, oxygen and iodine is 2,3-diamino phenazine (benzophenazine), the structure unit is connected through an N atom to form a long chain structure, in the pre-sulfurization process, the C-H on both sides of the benzene ring in the long chain structure is dehydrogenated and sulfidized to generate a sulfur branch, so the long chain skeleton is connected through the C-Sx-C (x≥1) branch, compared with the pre-oxidation method, the carbon loss is reduced. This is because: the traditional pre-oxidation process of carbon material is to expose the carbon precursor to an oxygen atmosphere above 300 DEG C, the precursor reacts with oxygen to introduce oxygen-containing functional groups (such as ester, ether, carboxylic acid) and form 3D cross-linked structure, which prevents the ordered arrangement of carbon layer and graphitization, and at higher temperature, the oxygen-containing functional groups escape to form a void microstructure. Traditional pre-oxidation: ①Oxygen is more reactive and can react with multiple sites of the precursor, the position and amount of oxygen cross-linking are more, which is difficult to control; ②The pre-oxidation reaction position and degree are difficult to control because the precursor is continuously exposed to a large excess of oxygen, and CO2 is generated during the pre-oxidation process, causing carbon loss and reducing carbon yield; ③The pre-oxidation temperature is higher, the reaction sites are more and the degree is greater, which is difficult to control, and more carbon is lost. The pre-sulfurization process adopted by the present application: ①The reaction activity of sulfur is lower than that of oxygen, the reaction site is selective, the reaction site is fixed and controllable, and only the C-H site on the benzene ring reacts to generate the C-Sx-C functional group, without generating a large amount of different types of sulfur-containing functional groups; ②In the pre-sulfurization process, the ratio of the precursor to sulfur can be adjusted, and the pre-sulfurization degree (the length of the cross-linked sulfur chain) can be controlled according to the stoichiometric ratio and the closed state of the reaction container; ③Pre-sulfurization does not cause carbon loss. In the third reaction process, carbonization is realized, the C-Sx-C (x≥1) branch generates desulfurization reaction to generate a short sulfur chain, the main chain generates denitrification, deoxidation and deiodination reaction, and the partial removal of heteroatoms is conducive to the formation of local micropores, which can provide accommodation space for high-capacity active materials, provide abundant catalytic sites for interface reaction, and provide active cavities for alkali metal deposition-stripping, realizing the multifunctionalization of carbon materials. The iodine element in the carbon material can participate in the formation of negative electrode SEI, can improve the ion conductivity and structural stability of the SEI layer, and then improve the cycle and rate performance of the material. In addition, the method also has the advantages of simple synthesis method, high product consistency and scaleable production.The present application can obtain the highest polymerization degree, the intermediate product with moderate oxidation and iodination degree by limiting the first reaction temperature. The product can be avoided from being over-oxidized, over-iodinated or insufficiently oxidized and iodinated in the subsequent steps by controlling the second reaction temperature and the third reaction temperature, thereby avoiding the problems of deviating from the content of heteroatoms and insufficient carbon content, and affecting the electrical properties of the material.

[0063] In some alternative embodiments, in S1, the time of the first reaction is 1-2880 minutes.

[0064] In some alternative embodiments, in S2, the time of the second reaction is 30-4320 minutes.

[0065] In some alternative embodiments, in S3, the time of the third reaction is 30-4320 minutes.

[0066] For example, the time of the first reaction can be 1 minute, 5 minutes, 30 minutes, 100 minutes, 500 minutes, 1000 minutes, 1200 minutes, 1500 minutes, 1700 minutes, 2000 minutes, 2300 minutes, 2500 minutes, 2700 minutes, 2880 minutes, or within a range consisting of any of the above values; the time of the second reaction can be 30 minutes, 100 minutes, 500 minutes, 1000 minutes, 1200 minutes, 1500 minutes, 1700 minutes, 2000 minutes, 2300 minutes, 2500 minutes, 2700 minutes, 3000 minutes, 3300 minutes, 3500 minutes, 3800 minutes, 4000 minutes, 4320 minutes, or within a range consisting of any of the above values; the time of the third reaction can be 30 minutes, 100 minutes, 500 minutes, 1000 minutes, 1200 minutes, 1500 minutes, 1700 minutes, 2000 minutes, 2300 minutes, 2500 minutes, 2700 minutes, 3000 minutes, 3300 minutes, 3500 minutes, 3800 minutes, 4000 minutes, 4320 minutes, or within a range consisting of any of the above values.

[0067] In some alternative embodiments, in S1, the molar ratio of the phenylenediamine, iodine-containing oxidizing agent, and sulfuration agent is 1:0.5-5:3-20. For example, the molar ratio of the phenylenediamine, iodine-containing oxidizing agent, and sulfuration agent can be 1:0.5:20, 1:1:17, 1:2:15, 1:3:10, 1:4:8, 1:5:3, or within a range consisting of any of the above values.

[0068] According to the above technical means, by limiting the molar ratio of raw materials, the content of doping elements can be controlled; in addition, by controlling the C-H dehydrogenation sulfuration rate and the length of the sulfur branched chain through the mixing molar ratio of the sulfuration agent and the phenylenediamine, the second reaction temperature, the second reaction time, and the closed state of the reaction container, the controllable doping of sulfur elements is realized, and by controlling the amount of nitrogen, oxygen, sulfur, and iodine elements through the third reaction temperature, the third reaction time, and the closedness of the reaction container, the electrical properties of the material are further controlled.

[0069] In some optional embodiments, the phenylenediamine includes at least one of o-phenylenediamine, p-phenylenediamine, and m-phenylenediamine;

[0070] And / or, the iodine-containing oxidizing agent includes at least one of sodium periodate, metaperiodic acid, orthoperiodic acid, lithium periodate, and potassium periodate;

[0071] And / or, the sulfuration agent includes at least one of elemental sulfur, sulfur dioxide, sulfur trioxide, metal polysulfide MxSy (M = Li, Na, K, Mg, y ≥ 2), tetramethylthiuram disulfide, tetraethylthiuram disulfide, dithiohexanolactam, and dithiodimorpholine.

[0072] In some optional embodiments, in S1, the oxygen-free environment is a vacuum, nitrogen, or inert gas environment;

[0073] And / or, the phenylenediamine is o-phenylenediamine;

[0074] And / or, the sulfuration agent is elemental sulfur.

[0075] According to the above technical means, the raw materials are preferably selected, and the application has the advantages of low cost, sustainable resources, and scalable production.

[0076] In some optional embodiments, in S1, the mixing method of the phenylenediamine, the iodine-containing oxidizing agent, and the sulfuration agent is stirring, grinding, ball milling, sand milling, including dry mixing and wet mixing with a liquid medium. If wet mixing is performed, the liquid medium is any one or more of water, ethanol, isopropanol, N,N-dimethylformamide, benzene, toluene, an acid solution (phosphoric acid, boric acid, nitric acid, etc.), an alkali solution (sodium hydroxide solution, potassium hydroxide solution, etc.), and a salt solution (sodium chloride, potassium chloride, ammonium chloride, etc.). The material after wet mixing is dried at -20°C to 200°C, and the drying method includes vacuum or air drying, freeze drying, spray drying, electrospinning, etc.

[0077] In some optional embodiments, the container for the reaction is in a sealed or semi-sealed state, with or without shaking or rotation, and the reactants are stirred or not stirred.

[0078] In some alternative embodiments, the heating method is heating furnace heating, oil / sand bath heating, or microwave heating, etc.

[0079] According to another aspect of the present application, an element co-doped carbon material is provided, which is prepared by the above preparation method.

[0080] According to the above technical means, the nitrogen, oxygen, sulfur, and iodine co-doped expanded carbon material prepared by the method of the present application, when used as a hard carbon negative electrode and a high-capacity silicon-carbon negative electrode host material of an alkali metal ion battery, the rich nitrogen, oxygen, sulfur, and iodine elements can act as active sites for alkali metal ions, and these elements are more Li + + When Lidiffuses in the carbon material, it will quickly transport on the channels formed by these elements, promoting the transport of alkali metal ions inside the electrode particles, thereby improving the rate performance; at the same time, the nitrogen, oxygen, sulfur, and iodine elements on the surface of the carbon material can participate in the formation of SEI components with good ionic conductivity, such as Li3N and LiI, promoting the diffusion of lithium ions to the inside, thus being beneficial to the internal material capacity release and improving the capacity performance. The iodine element participates in the formation of negative electrode SEI components as inorganic products, which are rigid and can improve the ionic conductivity and structural stability of the SEI layer, thereby improving the cycle performance of the material; when used as a sulfur positive electrode host material of an alkali metal sulfur battery, the nitrogen, oxygen, sulfur, and iodine elements can bind to alkali metal ions, promote ionic conductivity, adsorb and catalyze the conversion of alkali metal polysulfides, catalyze the solid-phase conversion between lithium sulfide and elemental sulfur in solid-state lithium-sulfur batteries, and improve the capacity and cycle performance of the alkali metal sulfur battery. As described above, the carbon material of the present application is rich in N, O, S, and I elements, and the binding energy of these elements to Li + , lithium polysulfide is higher than that of carbon, which can adsorb lithium polysulfide on the surface of the carbon material, avoid the loss of active material caused by a large amount of dissolution in the electrolyte, and the catalytic conversion of the heteroatom, especially I, to lithium polysulfide is strong, which can accelerate the chemical reaction process, the products are uniformly distributed, and the deactivation and polarization are avoided. In addition, the carbon material provided by the present application has abundant pores, which can accommodate more elemental sulfur and physically adsorb lithium polysulfide, and the above effects can effectively improve the capacity and cycle performance of the alkali metal sulfur battery.

[0081] According to another aspect of the present application, an alkali metal ion battery is provided, which comprises the above element co-doped carbon material.

[0082] In some alternative embodiments, the element co-doped carbon material is used as a negative electrode active material.

[0083] Alternatively, the element co-doped carbon material is used as a host material, and after depositing silicon, it is used as a negative electrode active material.

[0084] In the present application, the method for depositing silicon-carbon in the host material is conventional in the art, which can employ vapor deposition, liquid deposition, electrodeposition, etc.

[0085] In some alternative embodiments, the alkali metal ion battery comprises one of a lithium ion battery, a sodium ion battery, and a potassium ion battery.

[0086] According to yet another aspect of the present application, there is provided an alkali metal sulfur battery comprising the above-mentioned element co-doped carbon material; the element co-doped carbon material serves as a host material, and a sulfur-containing guest material is loaded in the host material.

[0087] Optionally, the sulfur-containing guest material comprises at least one of elemental sulfur, lithium sulfide, sodium sulfide, potassium sulfide, lithium polysulfide, sodium polysulfide, and potassium polysulfide.

[0088] In the present application, the method for loading the sulfur-containing guest material in the host material is conventional in the art, which can typically and non-limitingly achieve the loading of the sulfur-containing guest material by means of grinding, ball milling, sand milling, solution stirring, vapor deposition, spray drying, electrospinning, chemical reduction, etc.

[0089] In some alternative embodiments, the alkali metal sulfur battery comprises but is not limited to a lithium sulfur battery.

[0090] According to yet another aspect of the present application, there is provided an electric device comprising the above-mentioned alkali metal ion battery or the above-mentioned alkali metal sulfur battery.

[0091] The electric device provided by the present application has the same advantages as the above-mentioned battery, and thus will not be described here again.

[0092] It can be understood by those skilled in the art that the composition and preparation method of the alkali metal ion battery provided by the present application are conventional in the art. The following takes a lithium ion battery as an example for illustration: the lithium ion battery comprises positive electrode sheets, negative electrode sheets, electrolyte, separators, and a shell, etc. In the process of charging and discharging of the battery, lithium ions are embedded and extracted between the positive electrode sheets and the negative electrode sheets, the electrolyte plays a role in conducting ions between the positive electrode sheets and the negative electrode sheets, and the separator is arranged between the positive electrode sheets and the negative electrode sheets, mainly playing a role in preventing short circuit of the positive and negative electrodes, and at the same time allowing the lithium ions to pass through.

[0093] As an example, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode active layer is arranged on any one or both of the two opposite surfaces of the positive electrode current collector. The material, composition, and manufacturing method of the positive electrode sheet used in the lithium ion battery of the present application can comprise any technology disclosed in the prior art.

[0094] As an example, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer, the negative electrode current collector has two surfaces opposite in the thickness direction of the negative electrode current collector, and the negative electrode active layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector. The material of the negative electrode sheet used in the lithium ion battery of the present application, the composition thereof and the manufacturing method thereof can include any technology disclosed in the prior art.

[0095] The material and shape of the separator used in the lithium ion battery of the present application are not particularly limited, and can include any technology disclosed in the prior art.

[0096] As understood by those skilled in the art, the electrolyte plays a role of conducting ions between the positive electrode sheet and the negative electrode sheet, and the electrolyte used in the lithium ion battery of the present application can include any technology disclosed in the prior art. As an example, the electrolyte can include lithium salt, solvent, etc. In some embodiments, the electrolyte can also optionally include additives. For example, the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and can also include additives capable of improving certain properties of the battery, such as additives capable of improving the overcharge performance of the battery, additives capable of improving the high-temperature or low-temperature performance of the battery, etc.

[0097] The present application does not make specific limitations on the manufacturing method of the lithium ion battery, and the lithium ion battery can be prepared by using conventional manufacturing methods in the art. For example, the positive electrode sheet, the separator and the negative electrode sheet are sequentially stacked with the separator between the positive electrode sheet and the negative electrode sheet, and the electrode core is obtained by stacking or winding process, and then the lithium ion battery of the present application can be obtained by going through processes such as baking, liquid injection, formation, packaging, etc.

[0098] It can be understood that the lithium ion battery provided in the electric device of the present application can be used as a power source of the electric device, or can be used as an energy storage unit of the electric device. The electric device can be, but is not limited to, a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0099] The present application will be described below with reference to specific examples, and it should be noted that these examples are merely descriptive and do not limit the present application in any way.

[0100] Example 1

[0101] The present example provides an element co-doped carbon material, the composition and the manufacturing method thereof are as follows:

[0102] (1) o-phenylenediamine, sodium periodate and elemental sulfur were added into a ball mill jar in a molar ratio of 1:1:9, and ball milling beads were added in a ball-to-charge ratio of 4:1, and the reaction mixture was ball milled at a rotation speed of 200 rpm for 2 h to fully mix the reactants.

[0103] (2) The mixed reactants in step (1) were poured into a ceramic pot, which was then placed in a stainless steel reaction kettle, and the kettle was sealed with a high-temperature-resistant fluorine rubber ring. The reaction vessel was heated to 200°C at a heating rate of 0.5°C / min in a nitrogen atmosphere, and the reaction vessel was kept at this temperature for 5 h. The o-phenylenediamine monomer was fully oxidized and polymerized by the oxygen produced by the decomposition of sodium periodate, and an iodization reaction occurred with sodium periodate and its thermal decomposition products, sodium periodate and sodium iodate, to form oxygen and iodine co-doped poly-o-phenylenediamine, named CNOI119-200, and its micro-morphology is shown in Figure 1 .

[0104] (3) The oxygen and iodine co-doped poly-o-phenylenediamine in step (2) was further heated to 400°C at a heating rate of 0.5°C / min, and kept at this temperature for 5 h. At this temperature, the fluorine rubber sealing ring gradually deformed to form a semi-closed atmosphere. The gaseous and liquid elemental sulfur reacted with the oxygen and iodine co-doped poly-o-phenylenediamine to form oxygen and iodine co-doped sulfurized poly-o-phenylenediamine with a main chain of oxygen and iodine co-doped poly-o-phenylenediamine and a branched chain of C-Sx-C (x≥1) structure, named CNOSI119-400, and its micro-morphology is shown in Figure 2 . From the figure, it can be seen that the material contains abundant pore structure; the XRD structure is shown in Figure 3 . From the figure, it can be seen that compared with the oxygen and iodine co-doped poly-o-phenylenediamine, the diffraction peak of the graphitization (002) crystal plane at 26.5° is obviously shifted to the left, indicating that the stacking distance of the polymer skeleton is increased, which is beneficial to the increase of the carbon layer spacing after carbonization.

[0105] (4) The oxygen and iodine co-doped sulfurized poly-o-phenylenediamine in step (3) was further heated to 700°C at a heating rate of 0.5°C / min, and kept at this temperature for 10 h. At this temperature, the fluorine rubber sealing ring was completely deformed and lost its sealing property. The oxygen and iodine co-doped sulfurized poly-o-phenylenediamine began to lose weight, and part of the hydrogen, carbon, nitrogen, oxygen, sulfur and iodine was removed, forming a stacked and porous structure, and a nitrogen, oxygen, sulfur and iodine co-doped expanded layer carbon crude product was obtained.

[0106] (5) The nitrogen, oxygen, sulfur and iodine co-doped expanded layer carbon crude product in step (4) was washed several times with water and ethanol to remove inorganic salts, monomer residues or oligomers, and vacuum dried at 80°C for 12 h to obtain the final product, a nitrogen, oxygen, sulfur and iodine co-doped expanded layer carbon material, named CNOSI119-700.

[0107] Example 2

[0108] The present embodiment provides an element co-doped carbon material, the composition and preparation method are as follows:

[0109] (1) The molar ratio of o-phenylenediamine, sodium periodate and elemental sulfur is 1:4:20, and the ball milling jar is added with ethanol with a liquid / solid mass ratio of 1:5 and ball milling beads with a ball / charge ratio of 5:1. The mixture is ball milled at a speed of 300 rpm for 2 h, with a 10 min pause every 20 min to allow the reactants to mix thoroughly. The mixture is dried in a forced air drying oven at 60℃ for 6 h to obtain a mixed reactant.

[0110] (2) The mixed reactant in step (1) is added to a ceramic rotary tube furnace, the tube furnace is evacuated to a pressure below 0.1 MPa and sealed, the tube furnace is heated to 104℃ at a heating rate of 0.5℃ / min to melt the o-phenylenediamine, and then the tube furnace is heated to 260℃ at a heating rate of 0.5℃ / min, and the o-phenylenediamine is allowed to fully polymerize and iodize to form an oxygen and iodine co-doped poly-o-phenylenediamine, named CNOI1420-260.

[0111] (3) Nitrogen is continuously introduced into the tube furnace at a speed of 20 mL / min, and the CNOI1420-260 in step (2) is continuously heated to 350℃ at a heating rate of 0.5℃ / min, and the CNOI41271 is allowed to dehydrogenate and sulfide for 10 h to obtain an oxygen and iodine co-doped sulfidized poly-o-phenylenediamine, named CNOSI1420-350.

[0112] (4) The CNOSI1420-350 in step (3) is continuously heated to 600℃ at a heating rate of 0.5℃ / min, and the CNOSI1420-350 loses weight and releases part of the hydrogen, carbon, nitrogen, oxygen, sulfur and iodine to form a stacked and porous structure, and the nitrogen, oxygen, sulfur and iodine co-doped expanded layer carbon crude product is obtained after natural cooling.

[0113] (5) The nitrogen, oxygen, sulfur and iodine co-doped expanded layer carbon crude product in step (4) is washed several times with water and ethanol to remove inorganic salts, monomer residues or oligomers, and vacuum dried at 80℃ for 12 h to obtain the final product of nitrogen, oxygen, sulfur and iodine co-doped expanded layer carbon material, named CNOSI1420-600.

[0114] Example 3

[0115] The present embodiment provides an element co-doped carbon material, which is different from Example 1 in that high iodate is used instead of sodium periodate and m-phenylenediamine is used instead of o-phenylenediamine in step (1), and the molar ratio of m-phenylenediamine, high iodate and elemental sulfur is 1:0.5:3.

[0116] Example 4

[0117] The present example provides an element co-doped carbon material, compared with Example 1, the difference lies in that the molar ratio of o-phenylenediamine, sodium periodate and elemental sulfur in step (1) is 1:5:20.

[0118] Example 5

[0119] The present example provides an element co-doped carbon material, compared with Example 1, the difference lies in that the molar ratio of o-phenylenediamine, sodium periodate and elemental sulfur in step (1) is 1:3:15.

[0120] Example 6

[0121] The present example provides an element co-doped carbon material, compared with Example 1, the difference lies in that the temperature and time of the first reaction, the second reaction and the third reaction are different, specifically as follows: in step (2), the reaction container is heated to 270℃ and kept for 20h; in step (3), it is continuously heated to 290℃ and kept for 72h; in step (4), it is continuously heated to 2000℃ and kept for 0.5h.

[0122] Example 7

[0123] The present example provides an element co-doped carbon material, compared with Example 1, the difference lies in that the temperature and time of the first reaction, the second reaction and the third reaction are different, specifically as follows: in step (2), the reaction container is heated to 50℃ and kept for 48h; in step (3), it is continuously heated to 420℃ and kept for 0.5h; in step (4), it is continuously heated to 1000℃ and kept for 72h.

[0124] Example 8

[0125] The present example provides an element co-doped carbon material, compared with Example 1, the difference lies in that the temperature and time of the first reaction, the second reaction and the third reaction are different, specifically as follows: in step (2), the reaction container is heated to 240℃ and kept for 24h; in step (3), it is continuously heated to 350℃ and kept for 36h; in step (4), it is continuously heated to 1200℃ and kept for 36h.

[0126] Comparative Example 1

[0127] The present example provides an element co-doped carbon material, compared with Example 1, the difference lies in that the first reaction and the second reaction are combined, that is, the reactor is directly heated to 200℃ and kept for 10h; then the subsequent third reaction and the like steps are carried out according to the example.

[0128] Comparative Example 2

[0129] The comparative example provides an element co-doped carbon material, which is different from Example 1 in that the first reaction and the second reaction are combined, i.e. the reactor is directly heated to 400°C for 10 h; and then subsequent third reaction and the like steps are performed according to the example.

[0130] Comparative Example 3

[0131] The comparative example provides an element co-doped carbon material, which is different from Example 1 in that the iodine-containing oxidizing agent is not included, and an equimolar amount of ammonium persulfate is used instead.

[0132] Comparative Example 4

[0133] The comparative example provides an element co-doped carbon material, which is different from Example 1 in that the carbonization step is not included, i.e. step (4) is not included.

[0134] Comparative Example 5

[0135] The comparative example provides an element co-doped carbon material, which is different from Example 1 in that an equimolar amount of aniline is used instead of o-phenylenediamine.

[0136] Application Example

[0137] 1. Application of the element co-doped carbon material as a hard carbon negative electrode for lithium ion batteries

[0138] (1) The element co-doped carbon material provided by each example and comparative example is mixed with conductive agent Super P and adhesive polyvinylidene fluoride in a mass ratio of 8:1:1, and N-methylpyrrolidone is used as a solvent to prepare a slurry, which is coated on a copper foil, and the surface density is controlled to be 15 mg / cm 2 . After vacuum drying at 80°C, rolling is performed to make the compacted density reach 1.2 g / cm 3 , and the electrode sheet is cut into a diameter of 12 mm.

[0139] (2) The electrode sheet prepared in step (1) is used as a working electrode, a lithium metal sheet is used as a counter electrode, a polypropylene film is used as a separator, 1M LiPF6 / carbonic acid ethylene (EC)-carbonic acid diethyl ester (DEC) is used as an electrolyte, and the volume ratio of EC and DEC is 1:1, and a CR2025 type button cell is assembled in an argon-filled glove box.

[0140] (3) The cell prepared in step (2) is charged and discharged in a voltage range of 0.01-2.0V at a current density of 100 mAg -1 , and the charge and discharge curve of Example 1 is shown in Figure 4 . CNOSI119-700 shows obvious high potential slope region and low potential platform region characteristics, and has typical hard carbon material characteristics.

[0141] Cycling performance: Under the same voltage range (0.01-2.0V), charge and discharge cycles were performed at a current density of 100mA / g, and the number of cycles before the capacity dropped to 80% of the initial discharge capacity was recorded.

[0142] Rate performance: Charge and discharge at a current density of 2000 mA / g within the same voltage range (0.01-2.0V), obtain the first discharge capacity at this current density, and calculate the percentage of its capacity to the first discharge capacity at a current density of 100 mA / g.

[0143] Table 1

[0144]

[0145] 2. Application of element-co-doped carbon materials in lithium-sulfur batteries

[0146] (1) Weigh the element co-doped carbon materials and elemental sulfur provided in each embodiment and comparative example at a mass ratio of 1:3 and add them to a mortar. After grinding for 30 minutes, place them in a threaded graphite jar. Put the screwed-on graphite jar into a tube furnace and continuously introduce nitrogen gas. Heat the furnace to 300°C at a rate of 5°C / min and keep it at that temperature for 5 hours. After natural cooling, the element co-doped carbon material@S cathode material is obtained.

[0147] (2) The element co-doped carbon material @S cathode material in step (1) is used as the active material and ground with Ketjen black and sulfide electrolyte Li6PS5Cl at a mass ratio of 6:1:3 for 30 min. The mixture is then layered and assembled with sulfide electrolyte Li6PS5Cl and lithium indium alloy (lithium to indium molar ratio of 3:7) under a pressure of 3t to form a sandwich structure all-solid-state lithium-sulfur mold battery.

[0148] (3) The all-solid-state lithium-sulfur mold battery from step (2) is subjected to a voltage range of 0.4-2.5V and a flow rate of 1000 mAg. -1 The current density was used for charging and discharging at room temperature, and its charge-discharge curve is shown below. Figure 5 As shown, it exhibits typical solid-phase transformation single-platform characteristics.

[0149] (4) The all-solid-state lithium-sulfur mold battery from step (2) is subjected to a voltage range of 0.4-2.5V and a flow rate of 1000 mAg. -1 The current density was used to perform charge-discharge cycles at room temperature, and the number of cycles was recorded until the capacity dropped to 80% of the first discharge capacity.

[0150] Table 2

[0151]

[0152] 3. Application of elementally co-doped carbon materials in silicon-carbon anodes of lithium-ion batteries

[0153] (1) The element co-doped carbon material provided by each example and the comparative example was subjected to gas phase silicon deposition in a fluidized bed device, 5 kg of element co-doped carbon material powder was added, high-purity argon gas was passed for 30 min at a flow rate of 10 L / min; then the temperature was raised to 560°C, and after keeping the temperature for 30 min, silane gas was introduced at a flow rate of 0.1 L / min, and the flow rate of high-purity argon gas was kept unchanged at 10 L / min, the deposition was stopped after 8 h, the flow rate of high-purity argon gas was kept unchanged at 10 L / min, the heating was turned off, and the temperature was naturally cooled to room temperature. Thus, a gas phase silicon-carbon composite material based on a nitrogen, oxygen, sulfur and iodine co-doped expanded layer carbon material was obtained, which was named element co-doped carbon material@Si.

[0154] (2) The element co-doped carbon material@Si in step (1) was used as an active material, and was ground with gas phase grown carbon fiber (VGCF) and a sulfide electrolyte at a mass ratio of 70:2:28 for 30 min, and was layered with a sulfide electrolyte Li6PS5Cl and a lithium-indium alloy (the molar ratio of lithium to indium was 3:7) under a pressure of 3 t to assemble a full solid-state mold battery in a sandwich structure.

[0155] (3) The full solid-state mold battery in step (2) was subjected to charge and discharge at a voltage in the range of -0.6-0.9 V (vs. Li-In) at a rate of 0.5 C at room temperature, and the charge and discharge curves are shown in FIG. 1. Figure 6

[0156] Cycle performance: The charge and discharge cycles were carried out at a current density of 100 mA / g in the same voltage range (-0.6-0.9 V), and the cycle number at which the capacity decreased to 80% of the initial discharge capacity was recorded.

[0157] Rate performance: The charge and discharge were carried out at a current density of 2000 mA / g in the same voltage range (-0.6-0.9 V), the initial discharge capacity at this current density was obtained, and the percentage of the capacity at this current density to the initial discharge capacity at a current density of 100 mA / g was calculated.

[0158] Table 3

[0159]

[0160] From the test results of the above application examples, it can be seen that, without sufficient oxidation polymerization at the first reaction temperature, iodization, no iodine element doping, no controllable carbonization at the third reaction temperature, and no use of phenylenediamine with two amino groups as a monomer, the carbon material with multiple element effective doping provided by the present application cannot be obtained, and when it is used as a hard carbon negative electrode, a lithium-sulfur battery sulfur carrier, and a silicon-carbon negative electrode silicon carrier, its performance is not as good as that of the N, O, S and I co-doped porous carbon material provided by the present application.

[0161] ​Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from this still fall within the protection scope of the present application.

Claims

1. A method for preparing an elementally co-doped carbon material, characterized in that, Includes the following steps: S1, phenylenediamine, iodine-containing oxidizing agent and sulfiding agent are mixed and the first reaction is carried out in an anaerobic environment at 50℃~279℃; S2, heated to 280℃~420℃, to carry out the second reaction; S3, heated to 500℃~2000℃, to carry out the third reaction.

2. The method for preparing elementally co-doped carbon materials according to claim 1, characterized in that, In S1, the time for the first reaction is 1 to 2880 minutes; And / or, in S2, the time for the second reaction is 30 to 4320 minutes; And / or, in S3, the time for the third reaction is 30 to 4320 minutes.

3. The method for preparing elementally co-doped carbon materials according to claim 1, characterized in that, In S1, the molar ratio of the phenylenediamine, the iodine-containing oxidant, and the sulfiding agent is 1:0.5-5:3-20.

4. The method for preparing elementally co-doped carbon materials according to any one of claims 1-3, characterized in that, The phenylenediamine includes at least one of o-phenylenediamine, p-phenylenediamine, and m-phenylenediamine; And / or, the iodine-containing oxidant includes at least one of sodium periodate, metaperiodic acid, orthoperiodic acid, lithium periodate, and potassium periodate; And / or, the vulcanizing agent includes at least one of elemental sulfur, sulfur dioxide, sulfur trioxide, metal polysulfides, tetramethylthiuram disulfide, tetraethylthiuram disulfide, dithiocaprolactam, and dithiodimorpholine.

5. The method for preparing elementally co-doped carbon materials according to claim 4, characterized in that, In S1, the oxygen-free environment is a vacuum, nitrogen, or inert gas environment; And / or, the phenylenediamine is o-phenylenediamine; And / or, the vulcanizing agent is elemental sulfur.

6. A carbon material co-doped with elements, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. An alkali metal ion battery, characterized in that, Including the elementally co-doped carbon material as described in claim 6.

8. The alkali metal ion battery according to claim 7, characterized in that, The element-co-doped carbon material is used as the negative electrode active material; Alternatively, the element-co-doped carbon material can be used as the host material, and after silicon deposition, it can be used as the negative electrode active material.

9. An alkali metal sulfur battery, characterized in that, Includes the elementally co-doped carbon material as described in claim 6; wherein the elementally co-doped carbon material serves as a host material, and the host material contains a sulfur-containing guest material. Optionally, the sulfur-containing guest material includes at least one of elemental sulfur, lithium sulfide, sodium sulfide, potassium sulfide, lithium polysulfide, sodium polysulfide, and potassium polysulfide.

10. An electrical appliance, characterized in that, This includes the alkali metal ion battery of claim 8 or the alkali metal sulfur battery of claim 9.

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