A high-entropy nonmetallic carbon nanomaterial, its preparation method and application

Abstract

This invention discloses a high-entropy non-metallic carbon nanomaterial, its preparation method, and its application, belonging to the field of lithium-sulfur battery technology. This invention aims to solve the technical problems of severe polysulfide shuttle effect, poor high-rate cycle stability, and limited catalytic adsorption capacity of traditional single / dual-element doped carbon materials in existing lithium-sulfur batteries. This invention uses nitrogen-doped porous carbon as a carrier, and then sequentially introduces two completely different non-metallic sources. A high-entropy non-metallic carbon nanomaterial is prepared through a two-step segmented high-temperature calcination process. The doping elements include nitrogen and at least four selected from phosphorus, sulfur, selenium, boron, fluorine, bromine, and iodine. This material is then coated onto the surface of a commercial separator to obtain a modified separator. This invention utilizes the synergistic effect of multiple non-metallic elements to construct a three-dimensional conductive network and simultaneously achieve efficient catalysis and adsorption of polysulfides. The lithium-sulfur battery using this modified separator achieves an initial discharge specific capacity of 779.7 mAh / g at 5C rate, and a remaining capacity of 379.5 mAh / g after 500 cycles, exhibiting excellent high-rate cycle stability.

Description

Technical Field

[0001] This invention belongs to the technical field of lithium-sulfur batteries, and particularly relates to a porous carbon material. Background Technology

[0002] With the rapid development of electric vehicles and large-scale energy storage, the development of next-generation rechargeable batteries with high energy density has become an urgent need. Lithium-sulfur batteries, with their high theoretical specific capacity (1675 mAh / g) and energy density (2600 Wh / kg), as well as the advantages of abundant sulfur resources, low cost, and environmental friendliness, are widely regarded as the most promising candidate system. However, the commercialization of lithium-sulfur batteries still faces many challenges: the actual energy density is far lower than the theoretical value due to the low density of elemental sulfur and the large amount of electrolyte required; the electronic insulation of sulfur (S8) and its discharge product lithium sulfide (Li2S) leads to increased cathode polarization and decreased capacity utilization; the difference in mass density between sulfur and Li2S causes volume expansion, resulting in irreversible damage to the cathode structure; and the shuttle effect of lithium polysulfides (LiPSs) severely affects the cycle life of the battery. These problems collectively limit the widespread application of lithium-sulfur batteries. One mainstream strategy to address these issues is to physically block or chemically adsorb polysulfides through separator modification to suppress their shuttle effect. Traditional carbon-based membrane coatings (such as graphene, carbon nanotubes, and Ketjen black) mainly rely on physical barriers and weak van der Waals forces, making it difficult to anchor polysulfides for long periods, and active materials are still prone to loss. Therefore, developing novel functionalized membrane modification materials with strong chemical bonding capabilities and synergistic effects of multiple active sites, and constructing efficient adsorption-catalytic conversion mechanisms, has become a key breakthrough in overcoming the cycle stability bottleneck of lithium-sulfur batteries and realizing their high energy density advantage. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a high-entropy non-metallic carbon nanomaterial, its preparation method, and its application. Through the synergistic effect formed by co-doping of multiple non-metallic elements (N, Se, P, S, B), it achieves strong chemical adsorption and rapid catalytic conversion of polysulfides. As a membrane modification layer, this material can effectively solve technical problems such as severe polysulfide shuttle effect, slow catalytic conversion kinetics, rapid capacity decay at high rates, and weak physical adsorption and lack of chemically anchored active sites in traditional carbon-based membrane coatings.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] A method for preparing high-entropy non-metallic carbon nanomaterials includes the following steps:

[0006] (1) After mixing nitrogen-doped porous carbon with non-metallic source I, calcination I was performed under a protective atmosphere to obtain medium-entropy non-metallic nano-carbon material.

[0007] (2) After the medium-entropy non-metallic nano-carbon material is mixed evenly with non-metallic source II, it is calcined under a protective atmosphere to obtain high-entropy non-metallic nano-carbon material; wherein, the high-entropy non-metallic nano-carbon material refers to nano-carbon material with no less than 5 types of doped elements.

[0008] The nitrogen-doped porous carbon is prepared by hard salt template method, ZIF derivatization method or C3N4 derivatization method.

[0009] Preferably, the nitrogen-doped porous carbon is prepared by the hard salt template method, and the mass ratio of the hard salt template to the nitrogen-containing carbon source is 10:1-3.

[0010] Preferably, the hard salt template is sodium chloride, potassium chloride, magnesium chloride, sodium sulfate, or sodium silicate; and the nitrogen-containing carbon source is polyaniline, dopamine, chitosan, lysine, or adenine.

[0011] The non-metal source I and non-metal source II are each independently selected from any two or three of the phosphorus source, sulfur source, selenium source, boron source, fluorine source, bromine source and iodine source, and the doping elements contained in non-metal source II are completely different from those contained in non-metal source I.

[0012] Preferably, the non-metallic source I is a phosphorus source and a sulfur source, and the non-metallic source II is a boron source and a fluorine source.

[0013] Preferably, the non-metallic source I is a phosphorus source and a selenium source, and the non-metallic source II is a sulfur source and a boron source.

[0014] Preferably, the non-metallic source I is a boron source and a fluorine source, and the non-metallic source II is a selenium source and an iodine source.

[0015] Preferably, the non-metallic source I is a sulfur source and a bromine source, and the non-metallic source II is a phosphorus source and an iodine source.

[0016] Preferably, the non-metallic source I is a fluorine source and a selenium source, and the non-metallic source II is a boron source and a sulfur source.

[0017] Preferably, the non-metallic source I is a phosphorus source and a sulfur source, and the non-metallic source II is a boron source, a fluorine source, and a selenium source.

[0018] Preferably, the non-metallic source I is a boron source and a fluorine source, and the non-metallic source II is a phosphorus source, a selenium source, and a bromine source.

[0019] Preferably, the non-metallic source I is a selenium source and a bromine source, and the non-metallic source II is a phosphorus source, a sulfur source, and an iodine source.

[0020] Preferably, the non-metallic source I is a phosphorus source and a boron source, and the non-metallic source II is a fluorine source, a selenium source, and an iodine source.

[0021] Preferably, the non-metallic source I is a sulfur source and a fluorine source, and the non-metallic source II is a boron source, a bromine source, and an iodine source.

[0022] Preferably, the non-metallic source I is a phosphorus source, a sulfur source, and a boron source, and the non-metallic source II is a fluorine source and a selenium source.

[0023] Preferably, the non-metallic source I is a boron source, a fluorine source, and a selenium source, and the non-metallic source II is a phosphorus source and a bromine source.

[0024] Preferably, the non-metallic source I is a phosphorus source, a selenium source, and a bromine source, and the non-metallic source II is a sulfur source and an iodine source.

[0025] Preferably, the non-metallic source I is a sulfur source, a boron source, and a fluorine source, and the non-metallic source II is a selenium source and an iodine source.

[0026] Preferably, the non-metallic source I is a phosphorus source, a fluorine source, and an iodine source, and the non-metallic source II is a boron source and a bromine source.

[0027] Preferably, the non-metallic source I is a phosphorus source, a sulfur source, and a boron source, and the non-metallic source II is a fluorine source, a selenium source, and a bromine source.

[0028] Preferably, the non-metallic source I is a boron source, a fluorine source, and a selenium source, and the non-metallic source II is a phosphorus source, a bromine source, and an iodine source.

[0029] Preferably, the non-metallic source I is a phosphorus source, a selenium source, and a bromine source, and the non-metallic source II is a sulfur source, a boron source, and an iodine source.

[0030] Preferably, the non-metallic source I is a sulfur source, a boron source, and a fluorine source, and the non-metallic source II is a phosphorus source, a selenium source, and an iodine source.

[0031] Preferably, the non-metallic source I is a phosphorus source, a fluorine source, and a bromine source, and the non-metallic source II is a sulfur source, a selenium source, and an iodine source.

[0032] The calcination temperature of calcination I is 900-1000℃, and the holding time is 1-3h; the calcination temperature of calcination II is 800-1000℃, and the holding time is 1-3h.

[0033] The phosphorus source is any one or more of hexachlorocyclotriphosphazene, phosphoric acid, sodium hypophosphite, or red phosphorus; the sulfur source is any one or more of 4,4'-dihydroxydiphenyl sulfone, thiourea, or thiophene; the boron source is any one or more of boric acid, boron oxide, or sodium borohydride; the selenium source is selenium dioxide or elemental selenium; the fluorine source is any one or more of polytetrafluoroethylene, ammonium fluoride, or polyvinylidene fluoride; the bromine source is ammonium bromide or 1,2-dibromotetrafluoroethane; and the iodine source is ammonium iodide or elemental iodine.

[0034] The mass ratio of the nitrogen-doped porous carbon to non-metallic source I is 1:(2-30); the mass ratio of the medium-entropy non-metallic nanocarbon material to non-metallic source II is 1:(2-30).

[0035] Preferably, the non-metallic source I includes a phosphorus source and a sulfur source, and the mass ratio of the nitrogen-doped porous carbon to the phosphorus source and the sulfur source is 2-3:15-20:6-9; the non-metallic source II includes a selenium source and a boron source, and the mass ratio of the medium-entropy non-metallic nanocarbon material to the selenium source and the boron source is 1:1-2:1-2.

[0036] The method for mixing nitrogen-doped porous carbon and non-metallic source I in step (1) is as follows: nitrogen-doped porous carbon and non-metallic source I are added to a solvent and dispersed evenly to obtain a dispersion, which is then filtered or centrifuged, and washed and dried in sequence.

[0037] The solvent is selected from any one or a mixture of two or more of the following solvents: deionized water, anhydrous ethanol, methanol, isopropanol, N,N-dimethylformamide, and N-methylpyrrolidone.

[0038] The total solid mass concentration of nitrogen-doped porous carbon and non-metallic source I in the dispersion is 1-20 mg / mL.

[0039] The total solid mass concentration of nitrogen-doped porous carbon and non-metallic source I in the dispersion is 1-10 mg / mL.

[0040] The method for achieving uniform dispersion is ultrasonic dispersion, with an ultrasonic power of 100-500W and an ultrasonic time of 10-60min.

[0041] The drying process is vacuum drying, with a drying temperature of 60-120℃ and a drying time of 6-24 hours.

[0042] The method for mixing the medium-entropy non-metallic nano-carbon material with non-metallic source II in step (2) is as follows: mix and grind the medium-entropy non-metallic nano-carbon material with non-metallic source II.

[0043] A high-entropy non-metallic carbon nanomaterial is prepared by the above method. The doping elements of the high-entropy non-metallic carbon nanomaterial include nitrogen and at least four elements selected from phosphorus, sulfur, selenium, boron, fluorine and bromine.

[0044] The application of a high-entropy non-metallic nano-carbon material in lithium-sulfur batteries, wherein the high-entropy non-metallic nano-carbon material is used as a separator modification material or a positive electrode conductive carrier material in lithium-sulfur batteries.

[0045] The beneficial effects of this invention are:

[0046] This invention provides nitrogen-doped porous carbon materials that not only construct electron transport channels through a three-dimensional interconnected conductive network, significantly improving lithium-ion migration rate and charge conductivity of elemental sulfur, but also provide sufficient nitrogen for the preparation of high-entropy non-metallic carbon nanomaterials. Thanks to nitrogen doping, the conductivity of the carbon material is improved, effectively alleviating the insulation problem of elemental sulfur and its discharge products (Li₂S₂ / Li₂S). Simultaneously, the nitrogen-doped sites can also serve as catalytic centers, accelerating polysulfide conversion reactions and improving sulfur utilization and rate performance. This invention employs a two-step segmented doping process to introduce subsequent non-metallic elements. This allows for precise control of the calcination temperature and holding time at each step based on the pyrolysis characteristics of different non-metallic elements, ensuring efficient and uniform doping of various non-metallic elements into the carbon lattice. This avoids the problems of uneven doping, difficulty in effectively introducing some elements, or high-temperature volatilization loss caused by differences in element thermal stability during one-step doping. Building upon this foundation, non-metallic elements such as selenium, phosphorus, sulfur, and boron are further introduced, each playing a synergistic role: Selenium possesses intrinsic catalytic activity for polysulfide conversion reactions, reducing charge-discharge overpotentials, and can form Se–Li bonds with polysulfides, which is beneficial for capturing short-chain polysulfides, thereby reducing irreversible capacity loss; Phosphorus atoms, due to their radius (110 pm), cause carbon lattice expansion and distortion, generating more defective active sites, thereby enhancing mass transport and lithium-ion transport kinetics, and modulating electronic states through p-orbital interactions; Sulfur atoms strengthen polysulfide anchoring through spin polarization and exist at the carbon edge in a C–S–C form, providing additional redox active sites, while enhancing affinity through 3p–3p orbital overlap, effectively participating in electrochemical reactions; Boron, as an electron-deficient element, accelerates ion migration through electron-deficient delocalization, optimizes charge transfer using empty p orbitals, making adjacent carbon atoms positively charged and electrostatically adsorbing polysulfides, and promoting adsorption energy regulation through electron deficiency; In addition, B–N co-doping can form dipole active centers, further accelerating the reduction and oxidation kinetics of sulfur.

[0047] Experiments show that the membrane modified with this material has an initial discharge specific capacity of 1530.9 mAh / g at 0.1C rate; a specific capacity of 962.4 mAh / g after 200 cycles at 0.5C rate with a capacity retention of 71.48%; an initial discharge specific capacity of 779.7 mAh / g at 5C rate and a specific capacity of 379.5 mAh / g after 500 cycles. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 X-ray diffraction patterns of nitrogen-doped carbon nanomaterials N / C, medium-entropy non-metal-doped carbon nanomaterials 2N,P,S,B / C, and high-entropy non-metal-doped carbon nanomaterials 2N,Se,P,S,B / C.

[0050] Figure 2 Scanning electron microscope image of 2N / C;

[0051] Figure 3 Scanning electron microscope images of 2N, Se, P, S, B / C;

[0052] Figure 4 Transmission electron microscopy (TEM) image of 2N / C;

[0053] Figure 5 Transmission electron microscopy (TEM) images of 2N, Se, P, S, B / C.

[0054] Figure 6 Cyclic voltammetry curves of a lithium-sulfur battery with a 2N / C modified separator at a scan rate of 0.1 mV / s are shown.

[0055] Figure 7 Cyclic voltammetry curves of lithium-sulfur batteries with 2N,Se / C co-doped carbon material modified membrane at a scan rate of 0.1 mV / s are shown.

[0056] Figure 8 Cyclic voltammetry curves of lithium-sulfur batteries with 2N,Se,P,S,B / C modified separators at a scan rate of 0.1 mV / s are shown.

[0057] Figure 9 The constant current charge-discharge curves of lithium-sulfur batteries with 2N / C modified separators at different rates (0.1C to 8C) are shown.

[0058] Figure 10 The charge-discharge curves of lithium-sulfur batteries with 2N,Se / C modified separators at different rates (0.1C to 8C) are shown.

[0059] Figure 11 The charge-discharge curves of lithium-sulfur batteries with 2N,P,S,B / C modified separators at different rates (0.1C to 8C) are shown.

[0060] Figure 12 The charge-discharge curves of lithium-sulfur batteries with 2N,Se,P,S,B / C modified separators at different rates (0.1C to 8C) are shown.

[0061] Figure 13 This is a comparison chart of the rate performance of the examples and comparative examples at different rate ranges (0.1C to 8C);

[0062] Figure 14 The graph shows the cycle performance of a lithium-sulfur battery with a 2N / C modified separator at a 0.5C rate. From top to bottom, the graph represents the coulombic efficiency and the discharge specific capacity.

[0063] Figure 15 The graph shows the cycling performance of a lithium-sulfur battery with a 2N,Se / C modified separator at a rate of 0.5C. From top to bottom, the graph represents the coulombic efficiency and the discharge specific capacity.

[0064] Figure 16 The graph shows the cycle performance of a lithium-sulfur battery with a 2N,P,S,B / C modified separator at a rate of 0.5C. From top to bottom, the graph represents the coulombic efficiency and the discharge specific capacity.

[0065] Figure 17 The graph shows the cycling performance of a lithium-sulfur battery with a 2N,Se,P,S,B / C modified separator at a rate of 0.5C. From top to bottom, the graph represents the coulombic efficiency and the discharge specific capacity.

[0066] Figure 18 The graph shows the cycle performance of a lithium-sulfur battery with a 2N / C modified separator at a 2C rate, with coulombic efficiency and discharge specific capacity from top to bottom.

[0067] Figure 19 The graph shows the cycle performance of a lithium-sulfur battery with a 2N,Se / C modified separator at 2C rate. From top to bottom, the graph represents coulombic efficiency and discharge specific capacity.

[0068] Figure 20 The graph shows the cycle performance of a lithium-sulfur battery with a 2N,P,S,B / C modified separator at 2C rate. From top to bottom, the graph represents coulombic efficiency and discharge specific capacity.

[0069] Figure 21 The graph shows the cycling performance of a lithium-sulfur battery with a 2N,Se,P,S,B / C modified separator at a 2C rate. From top to bottom, the graph represents the coulombic efficiency and the discharge specific capacity.

[0070] Figure 22 The graph shows the cycling performance of a lithium-sulfur battery with a 2N,Se,P,S,B / C modified separator at a 5C rate.

[0071] Figure 23 The graph shows a comparison of the cycling performance of lithium-sulfur batteries with separators modified with six materials: 2N,Se,P,S / B / C, N,Se,P,S / B / C, 2N,Se,P,2S / B / C, 2N,2Se,P,S / B / C, 2N,P,S,B / C, and 2N,Se,P,B / C, at a 2C rate. From top to bottom, the graph represents coulombic efficiency and discharge specific capacity. Detailed Implementation

[0072] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0073] A universal method for preparing high-entropy nonmetallic carbon nanomaterials specifically includes the following steps:

[0074] I. Preparation of Nitrogen-Doped Carbon Precursors for High-Entropy Non-metallic Carbon Nanomaterials

[0075] Nitrogen-doped porous carbon was prepared by the hard salt template method: a hard salt template and a nitrogen-containing carbon source were mixed in a certain proportion and then mixed evenly by solid-phase grinding. The mixture was then calcined at high temperature. The resulting product was acid-washed with 2-5M hydrochloric acid 2-4 times, with stirring for 8-24 hours each time. After filtration and drying, the nitrogen-doped porous carbon material precursor was obtained.

[0076] II. Preparation of Nitrogen, Phosphorus, and Sulfur Co-doped Carbon Nanomaterials

[0077] 100-150 mg of the nitrogen-doped carbon nanomaterials obtained in step one are dispersed in 80-120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 650-975 mg of sulfur source and 300-450 mg of phosphorus source are dispersed in 100-150 ml of methanol and mixed evenly by stirring or ultrasonication. The dispersion of the nitrogen-doped carbon nanomaterials is poured into the dispersion of the sulfur and phosphorus sources, and stirred for 15-30 minutes. Then, 1-3 ml of triethylamine is added, and stirring continues for 8-24 hours. The mixture is then filtered or centrifuged, washed 3-6 times with methanol, and vacuum dried at 50-80°C. The dried sample is placed in a ceramic boat and transferred to a tube furnace with a protective gas atmosphere. It is heated to 900-1000°C at a heating rate of 5°C / min for sintering, held at that temperature for 1-3 hours, and then cooled to room temperature to obtain the nitrogen, phosphorus, and sulfur co-doped carbon nanomaterial composite.

[0078] III. Preparation of High-Entropy Nonmetal Co-doped Carbon Nanomaterials

[0079] The nitrogen, phosphorus, and sulfur co-doped carbon nanomaterials obtained in step two are mixed with boron and selenium sources at a mass ratio of 1:1-2:1-2. During the grinding process, 2-5 drops of anhydrous ethanol are added to promote uniform mixing, while the ethanol is evaporated using a heat lamp at 60-100℃. The dried mixture is then transferred to a tube furnace with an inert gas atmosphere and heated to 200-300℃ at a heating rate of 5℃ / min for sintering, holding at that temperature for 30-60 minutes. Subsequently, the temperature is further increased to 800-1000℃ at a heating rate of 5℃ / min, held at that temperature for 1-3 hours, and then cooled to room temperature to obtain high-entropy non-metallic doped carbon nanomaterials (denoted as 2N,Se,P,S,B / C).

[0080] IV. Preparation of membranes modified with high-entropy non-metallic nanocarbon materials

[0081] The high-entropy non-metallic doped carbon nanomaterials obtained in step three are mixed with conductive agents and binders at a mass ratio and placed in 25-50 ml of solvent. The mixture is then ultrasonically or stirred until it is evenly dispersed to obtain a slurry. The slurry is then uniformly coated onto the surface of a commercial membrane using a doctor blade coating method or a vacuum filtration method. After drying, the membrane modified with the high-entropy non-metallic carbon nanomaterials is obtained.

[0082] The grinding time in step one is 10-30 minutes, the gas flow rate is 50-100, and the rotation speed is 300-600 r / min.

[0083] Furthermore, the nitrogen source mentioned in step two is one or more of MOF-derived nitrogen-doped porous carbon, C3N4-derived nitrogen-doped porous carbon, or porous carbon prepared by salt template. These materials not only provide a carbon framework as a carbon support, but also provide nitrogen for the preparation of nitrogen, phosphorus, and sulfur co-doped nanocarbon materials. Nitrogen doping not only improves the conductivity of carbon materials and alleviates the insulation problem between elemental sulfur and discharge products (Li2S2 / Li2S), but also allows nitrogen doping sites to act as catalytic centers, accelerating polysulfide conversion reactions and improving sulfur utilization and rate performance. The phosphorus source is one or more of hexachlorocyclotriphosphazene, phosphoric acid, sodium hypophosphite, or red phosphorus, used to provide phosphorus for the preparation of nitrogen, phosphorus, and sulfur co-doped nanocarbon materials. The sulfur source is one or more of 4,4-dihydroxydiphenyl sulfone, thiourea, or thiophene, used to provide sulfur for the preparation of nitrogen, phosphorus, and sulfur co-doped nanocarbon materials.

[0084] Furthermore, in step two, the stirring / ultrasonic time is 15-30 minutes; the centrifugation speed is 6000-10000 / min; and the centrifugation time is 5-10 minutes.

[0085] Furthermore, the boron source mentioned in step three is one or more of boric acid, boron oxide, or sodium borohydride, used to provide boron for the preparation of high-entropy non-metallic doped carbon nanomaterials (2N,Se,P,S,B / C); the selenium source is one or more of selenium dioxide or elemental selenium, used to provide selenium for the preparation of high-entropy non-metallic carbon nanomaterials (2N,Se,P,S,B / C).

[0086] Further, in step four, the high-entropy non-metallic doped carbon nanomaterials obtained in step three are mixed with a conductive agent and a binder in a mass ratio of 6-7:3-2:1; the conductive agent is one or more of Ketjen Black, Super P, carbon nanotubes, graphene, and porous conductive carbon; the binder is one or more of PVDF (polyvinylidene fluoride), PEO (polyethylene oxide), PAA (polyacrylic acid), and CMC (carboxymethyl cellulose).

[0087] Furthermore, the protective gas in steps one, two, and three is either nitrogen or argon.

[0088] Example 1

[0089] A high-entropy non-metallic nano-carbon material (2N,Se,P,S,B / C) membrane modification material for lithium-sulfur batteries is prepared according to the following steps:

[0090] I. Preparation of Nitrogen-Doped Porous Carbon as a Carbon Support for High-Entropy Non-metallic Carbon Nanomaterials

[0091] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0092] II. Preparation of Nitrogen, Phosphorus, and Sulfur Co-doped Carbon Nanomaterials

[0093] 150 mg of the nitrogen-doped carbon nanomaterials obtained in step one were dispersed in 120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 975 mg of 4,4-dihydroxydiphenyl sulfone (sulfur source) and 450 mg of hexachlorocyclotriphosphazene (i.e., chlorophosphazene trimer, as phosphorus source) were dispersed in 150 ml of methanol and mixed evenly by stirring or ultrasonication. The dispersion of the nitrogen-doped carbon nanomaterials was poured into the dispersion of the sulfur and phosphorus sources, stirred for 20 minutes, and then 3 ml of triethylamine was added, with stirring continuing for 12 hours. The mixture was then filtered or centrifuged, washed three times with methanol, and vacuum dried at 70 °C. The dried sample was placed in a ceramic boat and transferred to a tube furnace under a protective gas atmosphere. It was heated to 1000 °C at a heating rate of 5 °C / min and sintered. After holding at this temperature for 2 hours, it was cooled to room temperature to obtain the nitrogen, phosphorus, and sulfur co-doped carbon nanomaterial composite.

[0094] III. Preparation of High-Entropy Nonmetallic (2N, Se, P, S, B) Co-doped Carbon Nanomaterials

[0095] The nitrogen, phosphorus, and sulfur co-doped nano-carbon composite material obtained in step two was mixed with boric acid and selenium dioxide at a mass ratio of 1:1:1. During the grinding process, 3 drops of anhydrous ethanol were added to promote uniform mixing, and the ethanol was evaporated using a heat lamp at 80°C. The dried mixture was transferred to a tube furnace with an inert gas atmosphere and heated to 300°C at a heating rate of 5°C / min for sintering, holding at that temperature for 30 minutes. Subsequently, the temperature was increased to 1000°C at a heating rate of 5°C / min, held at that temperature for 1 hour, and then cooled to room temperature to obtain the high-entropy non-metallic doped nano-carbon material (denoted as 2N,Se,P,S,B / C).

[0096] IV. Preparation of membranes modified with high-entropy non-metallic nanocarbon materials

[0097] The high-entropy non-metallic doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the high-entropy non-metallic carbon nanomaterials was obtained.

[0098] Example 2

[0099] A high-entropy non-metallic nano-carbon material (2N,Se,P,S,B / C) membrane modification material for lithium-sulfur batteries is prepared according to the following steps:

[0100] II. Preparation of Nitrogen-Doped Porous Carbon as a Carbon Support for High-Entropy Non-metallic Carbon Nanomaterials

[0101] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0102] II. Preparation of Nitrogen, Phosphorus, and Sulfur Co-doped Carbon Nanomaterials

[0103] 150 mg of the nitrogen-doped carbon nanomaterials obtained in step one were dispersed in 120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 975 mg of 4,4-dihydroxydiphenyl sulfone (sulfur source) and 450 mg of hexachlorocyclotriphosphazene (i.e., chlorophosphazene trimer, as phosphorus source) were dispersed in 150 ml of methanol and mixed evenly by stirring or ultrasonication. The dispersion of the nitrogen-doped carbon nanomaterials was poured into the dispersion of the sulfur and phosphorus sources, stirred for 20 minutes, and then 3 ml of triethylamine was added, with stirring continuing for 12 hours. The mixture was then filtered or centrifuged, washed three times with methanol, and vacuum dried at 70 °C. The dried sample was placed in a ceramic boat and transferred to a tube furnace with a protective gas atmosphere. It was heated to 900 °C at a heating rate of 5 °C / min and sintered. After holding at this temperature for 3 hours, it was cooled to room temperature to obtain the nitrogen, phosphorus, and sulfur co-doped carbon nanomaterial composite.

[0104] III. Preparation of High-Entropy Nonmetallic (2N, Se, P, S, B) Co-doped Carbon Nanomaterials

[0105] The nitrogen, phosphorus, and sulfur co-doped nano-carbon composite material obtained in step two was mixed with boric acid and selenium dioxide at a mass ratio of 1:1:1. During the grinding process, 3 drops of anhydrous ethanol were added to promote uniform mixing, and the ethanol was evaporated using a heat lamp at 80°C. The dried mixture was transferred to a tube furnace with an inert gas atmosphere and heated to 300°C at a heating rate of 5°C / min for sintering, holding at that temperature for 30 minutes. Subsequently, the temperature was increased to 900°C at a heating rate of 5°C / min, held at that temperature for 3 hours, and then cooled to room temperature to obtain the high-entropy non-metallic doped nano-carbon material (denoted as 2N,Se,P,S,B / C).

[0106] IV. Preparation of membranes modified with high-entropy non-metallic nanocarbon materials

[0107] The high-entropy non-metallic doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the high-entropy non-metallic carbon nanomaterials was obtained.

[0108] Example 3

[0109] A high-entropy non-metallic nano-carbon material (2N,Se,P,S,B / C) membrane modification material for lithium-sulfur batteries is prepared according to the following steps:

[0110] III. Preparation of Nitrogen-Doped Porous Carbon as a Carbon Support for High-Entropy Non-metallic Carbon Nanomaterials

[0111] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0112] II. Preparation of Nitrogen, Phosphorus, and Sulfur Co-doped Carbon Nanomaterials

[0113] 150 mg of the nitrogen-doped carbon nanomaterials obtained in step one were dispersed in 120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 975 mg of 4,4-dihydroxydiphenyl sulfone (sulfur source) and 450 mg of hexachlorocyclotriphosphazene (i.e., chlorophosphazene trimer, as phosphorus source) were dispersed in 150 ml of methanol and mixed evenly by stirring or ultrasonication. The dispersion of the nitrogen-doped carbon nanomaterials was poured into the dispersion of the sulfur and phosphorus sources, stirred for 20 minutes, and then 3 ml of triethylamine was added, with stirring continuing for 12 hours. The mixture was then filtered or centrifuged, washed three times with methanol, and vacuum dried at 70 °C. The dried sample was placed in a ceramic boat and transferred to a tube furnace under a protective gas atmosphere. It was heated to 1000 °C at a heating rate of 5 °C / min and sintered. After holding at this temperature for 2 hours, it was cooled to room temperature to obtain the nitrogen, phosphorus, and sulfur co-doped carbon nanomaterial composite.

[0114] III. Preparation of High-Entropy Nonmetallic (2N, Se, P, S, B) Co-doped Carbon Nanomaterials

[0115] The nitrogen, phosphorus, and sulfur co-doped nano-carbon composite material obtained in step two was mixed with boric acid and selenium dioxide at a mass ratio of 1:1:1. During the grinding process, 3 drops of anhydrous ethanol were added to promote uniform mixing, and the ethanol was evaporated using a heat lamp at 80°C. The dried mixture was transferred to a tube furnace with an inert gas atmosphere and heated to 300°C at a heating rate of 5°C / min for sintering, holding at that temperature for 30 minutes. Subsequently, the temperature was increased to 800°C at a heating rate of 5°C / min, held at that temperature for 1 hour, and then cooled to room temperature to obtain the high-entropy non-metallic doped nano-carbon material (denoted as 2N,Se,P,S,B / C).

[0116] IV. Preparation of membranes modified with high-entropy non-metallic nanocarbon materials

[0117] The high-entropy non-metallic doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the high-entropy non-metallic carbon nanomaterials was obtained.

[0118] Comparative Example 1: This comparative example provides a nitrogen-doped nano-carbon material (2N / C) membrane modification material for lithium-sulfur batteries and its preparation method, specifically following these steps:

[0119] I. Preparation of Nitrogen-Doped Carbon Nanomaterials

[0120] Nitrogen-doped porous carbon was prepared using a hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the nitrogen-doped nanocarbon precursor (2N / C) was obtained.

[0121] II. Preparation of nitrogen-doped carbon nanomaterial-modified membranes

[0122] The nitrogen-doped carbon nanomaterials obtained in step one were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the nitrogen-doped carbon nanomaterials was obtained.

[0123] Comparative Example 2: This comparative example provides a nitrogen and selenium co-doped nano-carbon material (2N,Se / C) membrane modification material for lithium-sulfur batteries and its preparation method, specifically following these steps:

[0124] I. Preparation of Nitrogen-Doped Carbon Nanomaterials

[0125] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0126] II. Preparation of Nitrogen-Selenium Co-doped Carbon Nanomaterials

[0127] 150 mg of the nitrogen-doped carbon nanomaterial obtained in step one was mixed with selenium dioxide at a mass ratio of 1:1. During the grinding process, 3 drops of anhydrous ethanol were added to promote uniform mixing, and the ethanol was evaporated at 80°C using a heating lamp. The dried mixture was transferred to a tube furnace with an inert gas atmosphere and heated to 300°C at a heating rate of 5°C / min for sintering, and held at that temperature for 30 minutes. Then, the temperature was increased to 1000°C at a heating rate of 5°C / min, held at that temperature for 1 hour, and then cooled to room temperature to obtain the nitrogen-selenium co-doped carbon nanomaterial (2N,Se / C).

[0128] III. Preparation of Nitrogen- and Selenium Co-doped Carbon Nanomaterial Modified Membranes

[0129] The nitrogen and selenium co-doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the nitrogen and selenium co-doped carbon nanomaterials was obtained.

[0130] Comparative Example 3: The preparation method of a medium-entropy non-metallic nano-carbon material (2N,P,S,B / C) membrane modification material for lithium-sulfur batteries in this comparative example is carried out according to the following steps:

[0131] I. Preparation of Nitrogen-Doped Carbon Nanomaterials

[0132] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0133] II. Preparation of Nitrogen, Phosphorus, and Sulfur Co-doped Carbon Nanomaterials

[0134] 150 mg of the nitrogen-doped carbon nanomaterials obtained in step one were dispersed in 120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 975 mg of 4,4-dihydroxydiphenyl sulfone (sulfur source) and 450 mg of hexachlorocyclotriphosphazene (i.e., chlorophosphazene trimer, as phosphorus source) were dispersed in 150 ml of methanol and mixed evenly by stirring or ultrasonication. The dispersion of the nitrogen-doped carbon nanomaterials was poured into the dispersion of the sulfur and phosphorus sources, stirred for 20 minutes, and then 3 ml of triethylamine was added, with stirring continuing for 12 hours. The mixture was then filtered or centrifuged, washed three times with methanol, and vacuum dried at 70 °C. The dried sample was placed in a ceramic boat and transferred to a tube furnace under a protective gas atmosphere. It was heated to 1000 °C at a heating rate of 5 °C / min and sintered. After holding at this temperature for 2 hours, it was cooled to room temperature to obtain the nitrogen, phosphorus, and sulfur co-doped carbon nanomaterial composite.

[0135] III. Preparation of Medium-Entropy Nonmetal-Doped Carbon Nanomaterials (2N, P, S, B / C)

[0136] The nitrogen, phosphorus, and sulfur co-doped nano-carbon composite material obtained in step two was mixed with boric acid at a mass ratio of 1:1:1. The mixture was then transferred to a tube furnace filled with inert gas and heated to 300°C at a heating rate of 5°C / min for sintering, and held at that temperature for 30 minutes. Subsequently, the temperature was further increased to 1000°C at a heating rate of 5°C / min, held at that temperature for 1 hour, and then cooled to room temperature to obtain the medium-entropy non-metallic doped nano-carbon material (2N,P,S,B / C).

[0137] IV. Preparation of Membranes Modified with Medium-Entropy Non-metallic Carbon Nanomaterials

[0138] The medium-entropy non-metallic doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the medium-entropy non-metallic carbon nanomaterials was obtained.

[0139] Comparative Example 4: The preparation method of a medium-entropy non-metallic nano-carbon material (2N,Se,P,B / C) membrane modification material for lithium-sulfur batteries in this comparative example is carried out according to the following steps:

[0140] I. Preparation of Nitrogen-Doped Carbon Nanomaterials

[0141] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0142] II. Preparation of Nitrogen-Phosphorus Co-doped Carbon Nanomaterials

[0143] 150 mg of the nitrogen-doped carbon nanomaterials obtained in step one were dispersed in 120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 450 mg of hexachlorocyclotriphosphazene (i.e., chlorophosphazene trimer, used as a phosphorus source) was dispersed in 150 ml of methanol and mixed evenly by stirring or ultrasonication. The aforementioned nitrogen-doped carbon nanomaterial dispersion was poured into the phosphorus source dispersion, stirred for 20 minutes, and then 3 ml of triethylamine was added. Stirring continued for 12 hours. Subsequently, the mixture was filtered or centrifuged, washed three times with methanol, and vacuum dried at 70 °C. The dried sample was placed in a ceramic boat and transferred to a tube furnace under a protective gas atmosphere. It was heated to 1000 °C at a heating rate of 5 °C / min and sintered. After holding at this temperature for 2 hours, it was cooled to room temperature to obtain the nitrogen-phosphorus co-doped carbon nanomaterial composite.

[0144] III. Preparation of Medium-Entropy Nonmetallic (2N, Se, P, B) Co-doped Carbon Nanomaterials

[0145] The nitrogen and phosphorus co-doped carbon nanomaterials obtained in step two were mixed with boric acid and selenium dioxide at a mass ratio of 1:1:1. During the grinding process, 3 drops of anhydrous ethanol were added to promote uniform mixing, and the ethanol was evaporated using a heat lamp at 80°C. The dried mixture was transferred to a tube furnace with an inert gas atmosphere and heated to 300°C at a heating rate of 5°C / min for sintering, holding at that temperature for 30 minutes. Subsequently, the temperature was increased to 1000°C at a heating rate of 5°C / min, held at that temperature for 1 hour, and then cooled to room temperature to obtain the medium-entropy non-metallic doped carbon nanomaterials (denoted as 2N,Se,P,B / C).

[0146] IV. Preparation of membranes modified with medium-entropy non-metallic nanocarbon materials (2N,Se,P,B / C)

[0147] The high-entropy non-metallic doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the medium-entropy non-metallic carbon nanomaterials was obtained.

[0148] Comparative Example 5: This comparative example provides a high-entropy non-metallic nano-carbon material (N,Se,P,S,B / C) membrane modification material for lithium-sulfur batteries and its preparation method, specifically following these steps:

[0149] I. Preparation of Nitrogen-Doped Porous Carbon as a Carbon Support for High-Entropy Non-metallic Carbon Nanomaterials

[0150] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:1 and then homogenized by solid-phase grinding. After homogenization by solid-phase grinding, the mixture was calcined at 900℃. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0151] II. Preparation of Nitrogen, Phosphorus, and Sulfur Co-doped Carbon Nanomaterials

[0152] 150 mg of the nitrogen-doped carbon nanomaterials obtained in step one were dispersed in 120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 975 mg of 4,4-dihydroxydiphenyl sulfone (sulfur source) and 450 mg of hexachlorocyclotriphosphazene (i.e., chlorophosphazene trimer, as phosphorus source) were dispersed in 150 ml of methanol and mixed evenly by stirring or ultrasonication. The dispersion of the nitrogen-doped carbon nanomaterials was poured into the dispersion of the sulfur and phosphorus sources, stirred for 20 minutes, and then 3 ml of triethylamine was added, with stirring continuing for 12 hours. The mixture was then filtered or centrifuged, washed three times with methanol, and vacuum dried at 70 °C. The dried sample was placed in a ceramic boat and transferred to a tube furnace under a protective gas atmosphere. It was heated to 1000 °C at a heating rate of 5 °C / min and sintered. After holding at this temperature for 2 hours, it was cooled to room temperature to obtain the nitrogen, phosphorus, and sulfur co-doped carbon nanomaterial composite.

[0153] III. Preparation of High-Entropy Nonmetallic (N, Se, P, S, B) Co-doped Carbon Nanomaterials

[0154] The nitrogen, phosphorus, and sulfur co-doped nano-carbon composite material obtained in step two was mixed with boric acid and selenium dioxide at a mass ratio of 1:1:1. During the grinding process, 3 drops of anhydrous ethanol were added to promote uniform mixing, and the ethanol was evaporated using a heat lamp at 80°C. The dried mixture was transferred to a tube furnace with an inert gas atmosphere and heated to 300°C at a heating rate of 5°C / min for sintering, holding at that temperature for 30 minutes. Subsequently, the temperature was increased to 1000°C at a heating rate of 5°C / min, held at that temperature for 1 hour, and then cooled to room temperature to obtain the high-entropy non-metallic doped nano-carbon material (denoted as N,Se,P,S,B / C).

[0155] IV. Preparation of membranes modified with high-entropy non-metallic nanocarbon materials

[0156] The high-entropy non-metallic doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the high-entropy non-metallic carbon nanomaterials was obtained.

[0157] Comparative Example 6: This comparative example provides a high-entropy non-metallic nano-carbon material (2N,2Se,P,S,B / C) membrane modification material for lithium-sulfur batteries and its preparation method, specifically following these steps:

[0158] I. Preparation of Nitrogen-Doped Carbon Nanomaterials

[0159] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0160] II. Preparation of Nitrogen, Phosphorus, and Sulfur Co-doped Carbon Nanomaterials

[0161] 150 mg of the nitrogen-doped carbon nanomaterials obtained in step one were dispersed in 120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 975 mg of 4,4-dihydroxydiphenyl sulfone (sulfur source) and 450 mg of hexachlorocyclotriphosphazene (i.e., chlorophosphazene trimer, as phosphorus source) were dispersed in 150 ml of methanol and mixed evenly by stirring or ultrasonication. The dispersion of the nitrogen-doped carbon nanomaterials was poured into the dispersion of the sulfur and phosphorus sources, stirred for 20 minutes, and then 3 ml of triethylamine was added, with stirring continuing for 12 hours. The mixture was then filtered or centrifuged, washed three times with methanol, and vacuum dried at 70 °C. The dried sample was placed in a ceramic boat and transferred to a tube furnace under a protective gas atmosphere. It was heated to 1000 °C at a heating rate of 5 °C / min and sintered. After holding at this temperature for 2 hours, it was cooled to room temperature to obtain the nitrogen, phosphorus, and sulfur co-doped carbon nanomaterial composite.

[0162] III. Preparation of High-Entropy Nonmetallic (2N, 2Se, P, S, B) Co-doped Carbon Nanomaterials

[0163] The nitrogen, phosphorus, and sulfur co-doped carbon nanomaterials obtained in step two were mixed with boric acid and selenium dioxide at the following mass ratios: sample to boric acid mass ratio 1:1, sample to selenium dioxide mass ratio 1:2. Three drops of anhydrous ethanol were added during grinding to promote uniform mixing, and the ethanol was evaporated using a heat lamp at 80°C. The dried mixture was transferred to a tube furnace purged with inert gas and heated to 300°C at a heating rate of 5°C / min for sintering, holding at that temperature for 30 minutes. Then, the temperature was increased to 1000°C at a further heating rate of 5°C / min, held for 1 hour, and then cooled to room temperature to obtain the high-entropy non-metallic doped carbon nanomaterials (denoted as 2N,2Se,P,S,B / C).

[0164] IV. Preparation of membranes modified with high-entropy non-metallic nanomaterials (2N, 2Se, P, S, B / C)

[0165] The high-entropy non-metallic doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the high-entropy non-metallic carbon nanomaterials was obtained.

[0166] Comparative Example 7: This comparative example provides a high-entropy non-metallic nano-carbon material (2N,Se,P,2S,B / C) membrane modification material for lithium-sulfur batteries and its preparation method, specifically following these steps:

[0167] I. Preparation of Nitrogen-Doped Carbon Nanomaterials

[0168] Nitrogen-doped porous carbon was prepared using the hard salt template method. Magnesium chloride hexahydrate and adenine were mixed at a mass ratio of 10:2 and then homogenized by solid-phase grinding. The mixture was then calcined at 900°C. The resulting product was acid-washed three times with 2M hydrochloric acid, with stirring for 12 hours each time. After filtration and drying, the precursor of nitrogen-doped nanocarbon material was obtained.

[0169] II. Preparation of Nitrogen, Phosphorus, and Sulfur Co-doped Carbon Nanomaterials

[0170] 150 mg of the nitrogen-doped carbon nanomaterials obtained in step one were dispersed in 120 ml of methanol and stirred evenly by ultrasonication or magnetic stirring. Separately, 1950 mg of 4,4-dihydroxydiphenyl sulfone (sulfur source) and 450 mg of hexachlorocyclotriphosphazene (i.e., chlorophosphazene trimer, as phosphorus source) were dispersed in 150 ml of methanol and mixed evenly by stirring or ultrasonication. The dispersion of the nitrogen-doped carbon nanomaterials was poured into the dispersion of the sulfur and phosphorus sources, stirred for 20 minutes, and then 3 ml of triethylamine was added. Stirring continued for 12 hours. The mixture was then filtered or centrifuged, washed three times with methanol, and vacuum dried at 70 °C. The dried sample was placed in a ceramic boat and transferred to a tube furnace under a protective gas atmosphere. It was heated to 1000 °C at a heating rate of 5 °C / min and sintered. After holding at this temperature for 2 hours, it was cooled to room temperature to obtain the nitrogen, phosphorus, and sulfur co-doped carbon nanomaterial composite.

[0171] III. Preparation of High-Entropy Nonmetallic (2N, Se, P, 2S, B) Co-doped Carbon Nanomaterials

[0172] The nitrogen, phosphorus, and sulfur co-doped carbon nanomaterials obtained in step two were mixed with boric acid and selenium dioxide in a mass ratio of 1:1:1. Three drops of anhydrous ethanol were added during the grinding process to promote uniform mixing, while the ethanol was evaporated using a heat lamp at 80°C. The dried mixture was transferred to a tube furnace purged with inert gas and heated to 300°C at a rate of 5°C / min for sintering, holding at that temperature for 30 minutes. Then, the temperature was increased to 1000°C at a rate of 5°C / min, held for 1 hour, and then cooled to room temperature to obtain the high-entropy non-metallic doped carbon nanomaterials (denoted as 2N,Se,P,2S,B / C).

[0173] IV. Preparation of membranes modified with high-entropy non-metallic nanomaterials (2N, Se, P, 2S, B / C)

[0174] The high-entropy non-metallic doped carbon nanomaterials obtained in step three were mixed with carbon nanotubes and a binder (PVDF) at a mass ratio of 7:2:1 and placed in 25 ml of solvent. The mixture was then ultrasonically / stirred until uniformly dispersed to obtain a slurry. The slurry was then uniformly coated onto the surface of a commercial membrane using a vacuum filtration method. After drying, the membrane modified with the high-entropy non-metallic carbon nanomaterials was obtained.

[0175] The difference between Comparative Examples 1-4 and Example 1 lies in the type and quantity of doping elements in the nano-carbon materials; the difference between Comparative Examples 5-7 and Example 1 lies in the different doping contents of nitrogen, selenium, and sulfur elements in the nano-carbon materials. The non-metallic doped carbon nanomaterials prepared in Example 1 and Comparative Examples 1-7 were used as modification materials for lithium-sulfur battery separators, and the following tests were performed:

[0176] Performance characterization was performed on the above comparative examples and Example 1.

[0177] Figure 1 The X-ray diffraction patterns for the examples are based on nitrogen-doped carbon material (2N / C), medium-entropy non-metal-doped nanocarbon material (2N,P,S,B / C), and high-entropy non-metal-doped nanocarbon material (2N,Se,P,S,B / C). The XRD patterns show two carbon peaks at approximately 25° and 42°, with no other impurity peaks observed.

[0178] Figure 2 Scanning electron microscope image of 2N / C;

[0179] Figure 3 The image shows a scanning electron microscope (SEM) image of 2N,Se,P,S,B / C. The microstructure reveals that this high-entropy non-metallic carbon nanomaterial exhibits a sheet-like morphology. The three-dimensional porous conductive network formed by the stacking of these sheets can both physically block the shuttle movement of polysulfides and provide a fast electron transport channel and catalyze their conversion, thereby significantly improving the rate performance and cycle stability of lithium-sulfur batteries.

[0180] Figure 4 The images show the transmission electron microscope (TEM) image and mapping diagram of 2N / C. The mapping diagram shows that the N element is uniformly distributed.

[0181] Figure 5 The images show the transmission electron microscope (TEM) images and mapping diagrams of 2N, Se, P, S, B / C. The mapping diagrams show that N, P, S, Se, and B elements are uniformly distributed in the sample, indicating that multiple non-metallic elements were successfully introduced into the carbon structure.

[0182] The XPS elemental content analysis results of the 2N, Se, P, S, B / C and N / C samples prepared in Example 1 are shown in Table 1. The high-entropy samples successfully achieved co-doping of the five non-metallic elements.

[0183] Table 1

[0184]

[0185] Figure 6 The cyclic voltammetry curves of the lithium-sulfur battery with a 2N / C modified separator in the comparative example are shown at a scan rate of 0.1 mV / s. The CV curves show that the peak current of the oxidation peak is 2.9489 mA, and the peak currents of the reduction peaks are -1.0488 mA and -3.2099 mA, respectively; the polarization voltage is 0.380 V.

[0186] Figure 7The cyclic voltammetry curves of the lithium-sulfur battery with a 2N,P,S,B / C modified separator in the comparative example are shown at a scan rate of 0.1 mV / s. The results show that its oxidation peak current (3.07312 mA) is higher than that of the nitrogen-doped carbon material, while the two reduction peak currents (-0.94479 mA and -2.2666 mA) are lower; the polarization voltage (0.302 V) is also smaller. This indicates that while the 2N,P,S,B / C material can improve reaction reversibility (reduce polarization voltage), it also weakens the catalytic efficiency for the polysulfide reduction step, requiring a trade-off optimization.

[0187] Figure 8 The cyclic voltammetry curves of the lithium-sulfur battery with a 2N,Se,P,S,B / C modified separator in the examples are shown at a scan rate of 0.1 mV / s. The results show that it has the largest peak current (4.6766 mA) for oxidation and the largest peak currents (-1.0506 mA and -3.6808 mA) for both reduction peaks, while having the smallest polarization voltage (0.286 V). This indicates that N,Se,P,S,B / C exhibits the best conversion kinetics for polysulfides, likely due to the synergistic effect of multiple non-metallic elements, leading to a faster sulfur conversion rate.

[0188] Figure 9 The constant current charge-discharge curves of lithium-sulfur batteries with 2N / C modified separators in the comparative examples are shown at different rates (0.1C to 8C). Their initial discharge specific capacities were 1342.5 mAh / g (0.1C), 1114.3 mAh / g (0.2C), 972.4 mAh / g (0.5C), 877.6 mAh / g (1C), 802 mAh / g (2C), 749.6 mAh / g (3C), 687.4 mAh / g (5C), 624.3 mAh / g (7C), and 592.8 mAh / g (8C). The results indicate that when the separator is modified only with the 2N / C precursor, although its polar nitrogen-doped sites can chemically adsorb polysulfides, during constant current cycling, the limited adsorption sites gradually saturate due to fluctuations in intermediate product concentration and repeated impacts, leading to a persistent and difficult-to-eliminate shuttle effect. Therefore, it is necessary to introduce different types of polar adsorption sites to enhance the anchoring ability for polysulfides.

[0189] Figure 10The figures show the constant current charge-discharge curves of lithium-sulfur batteries with N,Se co-doped nanocarbon material (2N,Se / C) modified separators at different rates (0.1C to 8C) in the comparative examples. Their initial discharge specific capacities were 1461.7 mAh / g (0.1C), 1279.8 mAh / g (0.2C), 1144.9 mAh / g (0.5C), 1051.9 mAh / g (1C), 946.5 mAh / g (2C), 873.4 mAh / g (3C), 798.4 mAh / g (5C), 714.1 mAh / g (7C), and 661.3 mAh / g (8C). The results indicate that the 2N,Se / C modified separator exhibits superior performance compared to the separator modified material containing only nitrogen doping. Although N and Se dual doping has significantly improved electrochemical performance, in order to further enrich the types of polar adsorption sites and explore the synergistic effect among multiple non-metallic elements, we further designed a medium-entropy system (2N,P,S,B / C) co-doped with four elements: N,P,S,B.

[0190] Figure 11 The constant current charge-discharge curves of the lithium-sulfur battery with a 2N,P,S,B / C modified separator in the comparative example are shown at different rates (0.1C to 8C). Their initial discharge specific capacities were 1414.9 mAh / g (0.1C), 1230 mAh / g (0.2C), 1076.2 mAh / g (0.5C), 969.6 mAh / g (1C), 871.8 mAh / g (2C), 811.1 mAh / g (3C), 748.8 mAh / g (5C), 695.3 mAh / g (7C), and 660.6 mAh / g (8C). The results show that, compared to... Figure 5 and Figure 6 It can be observed that the capacity of batteries modified with 2N,P,S,B / C is generally lower than that of 2N,Se / C at various rates (e.g., 660.6 mAh / g vs 661.3 mAh / g at 8C, and 1414.9 mAh / g vs 1461.7 mAh / g at 0.1C). This indicates that simply increasing the variety of doping elements without optimizing their combination is insufficient to fully leverage the synergistic effect between multiple elements, and may even weaken performance due to site competition or structural distortion. Therefore, we further designed a high-entropy non-metallic doped carbon nanomaterial (2N,Se,P,S,B / C) containing five elements: N, Se, P, S, and B. The aim is to achieve optimal synergy of polar sites through a richer elemental combination and entropy stabilization effect, thereby comprehensively improving the adsorption and catalytic conversion capabilities of polysulfides.

[0191] Figure 12The figures show the constant current charge-discharge curves of lithium-sulfur batteries with 2N,Se,P,S,B / C modified separators at different rates (0.1C to 8C). The initial discharge specific capacities were 1484.4 mAh / g (0.1C), 1350.5 mAh / g (0.2C), 1246.8 mAh / g (0.5C), 1149.7 mAh / g (1C), 1039.4 mAh / g (2C), 972.5 mAh / g (3C), 884.3 mAh / g (5C), 809.2 mAh / g (7C), and 751.3 mAh / g (8C). The results indicate that 2N,Se,P,S,B / C, as a separator modification layer for lithium-sulfur batteries, exhibits significant advantages in rate performance, high capacity retention, and suppression of shuttle effects due to its multi-component synergistic adsorption-catalysis effect and entropy-enhanced structural stability. It is a superior separator modification strategy compared to dual-doping or even medium-entropy quaternary doping.

[0192] Figure 13 The figures show a comparison of the rate performance of the examples and comparative examples at different rates (0.1C to 8C). The figures visually demonstrate the superiority of the high-entropy non-metallic doping strategy in improving the rate performance of lithium-sulfur batteries, with the separator modified with 2N,Se,P,S,B / C achieving the best high-rate discharge capability.

[0193] Figure 14 The graph shows the cycling performance of a lithium-sulfur battery with a 2N / C modified separator at 0.5C rate. The discharge specific capacity decreased from an initial 1014.1 mAh / g to 529.2 mAh / g after 200 cycles (capacity retention of 52.18%). This relatively low discharge specific capacity indicates that while nitrogen-doped carbon materials can provide some chemisorption capacity, their cycling stability is far from adequate. Therefore, it is necessary to introduce multiple non-metallic elements to enhance the long-term anchoring and catalytic conversion of polysulfides.

[0194] Figure 15 The graph shows the cycling performance of a lithium-sulfur battery with a 2N,Se / C modified separator in the comparative example at 0.5C rate. The discharge specific capacity decreases from an initial 1089.2 mAh / g to 584.4 mAh / g after 200 cycles (capacity retention of 53.65%). The results indicate that while N,Se / C can slightly improve the initial discharge specific capacity at 0.5C rate, its improvement on cycle stability is extremely limited (capacity retention only increases from 52.18% with N doping to 53.65%). This suggests that relying solely on Se and N dual doping is insufficient for long-term anchoring and catalytic conversion of polysulfides; it is necessary to introduce more diverse non-metallic elements to construct a medium-to-high entropy system.

[0195] Figure 16The graph shows the cycling performance of a lithium-sulfur battery with a 2N,P,S,B / C modified separator in the comparative example at 0.5C rate. The discharge specific capacity decays from an initial 1005.9 mAh / g to 641.9 mAh / g after 200 cycles (capacity retention of 63.81%). The results indicate that although the initial capacity of the medium-entropy 2N,P,S,B doped battery is lower than that of the 2N,Se co-doped battery, its cycling stability is significantly better, demonstrating the effectiveness of the synergistic effect of multiple non-metallic elements in suppressing the shuttle effect. However, the issue of its lower initial capacity still needs to be addressed by further optimizing the element combination (such as introducing Se to construct a high-entropy system).

[0196] Figure 17 The graph shows the cycling performance of a lithium-sulfur battery with a 2N,Se,P,S,B / C modified separator at 0.5C rate, where the discharge specific capacity decreases from an initial 1346.4 mAh / g to 962.4 mAh / g after 200 cycles (capacity retention of 71.48%). The comparison shows that the separator modified with high-entropy non-metallic doped nanocarbon material (2N,Se,P,S,B / C) exhibits both the highest initial discharge specific capacity and the best cycling stability (71.48% retention after 200 cycles), significantly outperforming single N doping, N,Se dual doping, and medium-entropy N,P,S,B quaternary doping. This fully demonstrates the unique advantages of high-entropy design in lithium-sulfur battery separator modification.

[0197] Figure 18 The graph shows the cycling performance of a lithium-sulfur battery with a 2N / C modified separator in the comparative example at 2C rate. The discharge specific capacity decreased from an initial 851.7 mAh / g to 486.8 mAh / g after 300 cycles (capacity retention of 57.15%). The results indicate that single-N-doped carbon nanomaterials struggle to balance high capacity and long-term cycling stability at high 2C rates, necessitating a multi-element non-metallic doping strategy to improve their electrochemical performance.

[0198] Figure 19 The graph shows the cycling performance of a lithium-sulfur battery with a 2N,Se / C modified separator at 2C rate in the comparative example. The discharge specific capacity decays from an initial 1026.1 mAh / g to 697.5 mAh / g after 300 cycles (capacity retention of 67.97%). The results indicate that the 2N,Se / C modified separator exhibits both higher initial capacity (1026.1 mAh / g) and better cycle stability (67.97% retention after 300 cycles) at high 2C rates. The results also show that the initial capacity (884.9 mAh / g) and cycle stability (61.40%) of the medium-entropy N,P,S,B doped batteries at 2C rate are significantly inferior to those of the N,Se co-doped batteries (1026.1 mAh / g, 67.97%), suggesting that simply increasing the number of elements without optimizing their combination can be counterproductive.

[0199] Figure 20 The graph shows the cycling performance of the lithium-sulfur battery with a 2N,P,S,B / C modified separator in the comparative example at a 2C rate. The discharge specific capacity decreased from an initial 884.9 mAh / g to 543.3 mAh / g after 300 cycles (capacity retention of 61.40%).

[0200] Figure 21 The figure shows the cycling performance of a lithium-sulfur battery with a 2N,Se,P,S,B / C modified separator at 2C rate in the examples. The discharge specific capacity decreased from an initial 1090.4 mAh / g to 733.9 mAh / g after 300 cycles (capacity retention of 68.30%). The comparison shows that the 2N,Se,P,S,B / C modified separator exhibits the best initial discharge specific capacity (1090.4 mAh / g) and the highest cycling stability (68.30% retention after 300 cycles) at high 2C rates, significantly outperforming single N doping, N,Se dual doping, and medium-entropy N,P,S,B quaternary doping. This fully verifies the unique advantages of the high-entropy strategy in improving the high-rate cycling performance of lithium-sulfur batteries.

[0201] Figure 22 The figure shows the cycling performance of the lithium-sulfur battery with a 2N,Se,P,S,B / C modified separator in the examples at 5C rate. The discharge specific capacity decreased from an initial 779.7 mAh / g to 379.5 mAh / g after 500 cycles. The results indicate that the 2N,Se,P,S,B / C modified separator can still provide an initial capacity of 779.7 mAh / g at an ultra-high 5C rate and exhibits excellent high-rate cycling stability, further validating the superiority of the high-entropy strategy.

[0202] Figure 23 The graphs show a comparison of the cycling performance of lithium-sulfur batteries with separators modified with six different materials—2N,Se,P,S / B / C, N,Se,P,S / B / C, 2N,Se,P,2S / B / C, 2N,2Se,P,S / B / C, 2N,P,S,B / C, and 2N,Se,P,B / C—at 2C rate. The results indicate that the separator modified with 2N,Se,P,S / B / C can achieve both high capacity and long cycle stability at high rates.

[0203] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-entropy non-metallic carbon nanomaterials, characterized in that, Includes the following steps: (1) After mixing nitrogen-doped porous carbon with non-metallic source I, calcination I was performed under a protective atmosphere to obtain medium-entropy non-metallic nano-carbon material. (2) After the medium-entropy non-metallic carbon nanomaterials are mixed evenly with non-metallic source II, they are calcined under a protective atmosphere to obtain high-entropy non-metallic carbon nanomaterials. The high-entropy non-metallic carbon nanomaterials refer to carbon nanomaterials with at least 5 types of doped elements.

2. The method for preparing high-entropy non-metallic carbon nanomaterials according to claim 1, characterized in that, The nitrogen-doped porous carbon is prepared by hard salt template method, ZIF derivatization method or C3N4 derivatization method.

3. The method for preparing high-entropy non-metallic carbon nanomaterials according to claim 1, characterized in that, The non-metal source I and non-metal source II are each independently selected from any two or three of the phosphorus source, sulfur source, selenium source, boron source, fluorine source, bromine source and iodine source, and the doping elements contained in non-metal source II are completely different from those contained in non-metal source I.

4. The method for preparing high-entropy non-metallic carbon nanomaterials according to claim 1, characterized in that, The calcination temperature of calcination I is 900-1000℃, and the holding time is 1-3h; the calcination temperature of calcination II is 800-1000℃, and the holding time is 1-3h.

5. The method for preparing high-entropy non-metallic carbon nanomaterials according to claim 3, characterized in that, The phosphorus source is any one or more of hexachlorocyclotriphosphazene, phosphoric acid, sodium hypophosphite, or red phosphorus; the sulfur source is any one or more of 4,4'-dihydroxydiphenyl sulfone, thiourea, or thiophene; the boron source is any one or more of boric acid, boron oxide, or sodium borohydride; the selenium source is selenium dioxide or elemental selenium; the fluorine source is any one or more of polytetrafluoroethylene, ammonium fluoride, or polyvinylidene fluoride; the bromine source is ammonium bromide or 1,2-dibromotetrafluoroethane; and the iodine source is ammonium iodide or elemental iodine.

6. The method for preparing high-entropy non-metallic carbon nanomaterials according to claim 1, characterized in that, The nitrogen-doped porous carbon was prepared using the hard salt template method, with a mass ratio of hard salt template to nitrogen-containing carbon source of 10:1-3; the mass ratio of nitrogen-doped porous carbon to non-metallic source I was 1:2-30; and the mass ratio of medium-entropy non-metallic nanocarbon material to non-metallic source II was 1:2-30.

7. The non-metallic source I includes a phosphorus source and a sulfur source, and the mass ratio of the nitrogen-doped porous carbon to the phosphorus source and the sulfur source is 2-3:15-20:6-9; the non-metallic source II includes a selenium source and a boron source, and the mass ratio of the medium-entropy non-metallic nanocarbon material to the selenium source and the boron source is 1:1-2:1-2.

8. The method for preparing high-entropy non-metallic carbon nanomaterials according to claim 1, characterized in that, The method for mixing nitrogen-doped porous carbon and non-metallic source I in step (1) is as follows: nitrogen-doped porous carbon and non-metallic source I are added to a solvent and dispersed evenly to obtain a dispersion, which is then filtered or centrifuged, and washed and dried in sequence.

9. A high-entropy non-metallic carbon nanomaterial, characterized in that, The high-entropy non-metallic carbon nanomaterial is prepared by any one of claims 1-8, and the doping elements include nitrogen and at least four elements selected from phosphorus, sulfur, selenium, boron, fluorine, bromine and iodine.

10. The application of the high-entropy non-metallic carbon nanomaterial according to claim 9 in lithium-sulfur batteries, characterized in that, The high-entropy non-metallic carbon nanomaterials are used as membrane modification materials or positive electrode conductive carrier materials for lithium-sulfur batteries.

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