Phosphorus-carbon metal composite negative electrode material, preparation method and application thereof

Abstract

The application discloses a phosphorus-carbon metal composite negative electrode material, a preparation method and application thereof, and belongs to the technical field of material preparation. The preparation method of the phosphorus-carbon metal composite negative electrode material comprises the following steps: activating and pore-forming of a mixture of a carbon source compound, an activating agent and a molybdenum compound in an activating gas to obtain molybdenum-doped porous carbon; performing gas phase deposition of the molybdenum-doped porous carbon in red phosphorus gas and selenium gas to obtain phosphorus-selenium-molybdenum porous carbon; and performing gas phase deposition of the phosphorus-selenium-molybdenum porous carbon in sulfur vapor and carbon source vapor in sequence to obtain the phosphorus-carbon metal composite negative electrode material. The phosphorus-carbon metal composite negative electrode material utilizes molybdenum selenide and phosphorus to improve the specific capacity of the material, utilizes a porous structure to reduce the expansion of the molybdenum selenide, and utilizes sulfur-doped amorphous carbon deposited on the shell to improve the electronic conductivity of the material, and the application of the material to a sodium ion battery has the advantages of high specific capacity, good rate performance, low expansion and the like, and improved cycle performance.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and in particular to a phosphorus-carbon metal composite anode material, its preparation method, and its application. Background Technology

[0002] Currently, the main anode materials used in sodium-ion batteries on the market are hard carbon materials, which suffer from defects such as low specific capacity, poor charging ability at low potentials, and poor power performance, severely restricting the widespread application of sodium-ion batteries in the fields of high energy density and fast charging. While alloy materials have high specific capacity, their large expansion leads to lower cycle performance. Currently, metal selenides are considered one of the most promising anode materials for sodium-ion batteries, but their properties differ from those of Na+. + The alloy materials generated by the conversion reaction have attracted widespread attention due to their advantages such as low cost and high specific capacity. Among them, selenium sulfide (SeS) has been extensively studied due to its high theoretical capacity (1000mAh / g). However, the low electronic conductivity and large full-charge expansion of selenium sulfide itself restrict its application and promotion in sodium-ion batteries. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a phosphorus-carbon metal composite anode material, its preparation method, and its application, solving the technical problems of poor electronic conductivity and large full-charge expansion of selenium sulfide.

[0004] To achieve the above objectives, the technical solution adopted by the present invention includes:

[0005] The first aspect of this invention aims to provide a method for preparing a phosphorus-carbon metal composite anode material, comprising the following steps:

[0006] A mixture of carbon source compound, activator and molybdenum compound is activated in an activating gas to create pores, thus obtaining molybdenum-doped porous carbon;

[0007] Molybdenum-doped porous carbon was vapor-deposited in red phosphorus gas and selenium gas to obtain molybdenum selenide phosphide porous carbon.

[0008] Molybdenum selenide phosphate porous carbon is successively vapor-deposited in sulfur vapor and carbon source vapor to obtain phosphorus-carbon metal composite anode material.

[0009] This invention improves the specific capacity and reduces expansion by doping molybdenum-doped porous carbon with selenium sulfide. At the same time, it enhances the electronic conductivity of the material by relying on molybdenum-doped porous carbon and its outer shell coating with sulfur-doped amorphous carbon. When applied to sodium-ion batteries, it improves the specific capacity and charging capability of sodium-ion batteries.

[0010] Furthermore, the mass ratio of the carbon source compound, the activator, and the molybdenum compound is 100:10-30:5-20.

[0011] Furthermore, the carbon source compound is one or more of polyaniline, polypyrrole, polythiophene, melamine, or polydopamine; the activator is one or more of zinc carbonate, sodium carbonate, zinc chloride, sodium hydroxide, or potassium hydroxide; and the molybdenum compound is one or more of acetylmolybdenum, ammonium molybdate, diammonium molybdate, tetraammonium molybdate, sodium molybdate, or tricarbonyltris(propionitrile)molybdenum.

[0012] Furthermore, the activating gas is one or more of water vapor, carbon dioxide, or sulfur dioxide.

[0013] Furthermore, the method for preparing the molybdenum-doped porous carbon includes: mixing a carbon source compound, an activator, and a molybdenum compound, purging the air in the reaction vessel with an inert gas, then introducing an activation gas, heating to 400-600℃ and holding for 0.5-2 hours, stopping the introduction of the activation gas; then heating to 700-1000℃ and holding for 1-6 hours to obtain molybdenum-doped porous carbon.

[0014] Furthermore, the method for preparing the molybdenum selenide phosphorus porous carbon includes: depositing molybdenum-doped porous carbon under vacuum of 10-100 Pa and temperature of 400-700 °C by introducing red phosphorus gas and selenium gas at a volume ratio of 1-5:1 at a flow rate of 100-1000 SCCM for 60-600 min.

[0015] Furthermore, the method for vapor-phase deposition of the molybdenum selenide phosphide porous carbon in sulfur vapor and carbon source vapor sequentially includes: depositing the molybdenum selenide phosphide porous carbon at a temperature of 400-600℃, by sequentially introducing sulfur vapor for 60-600 min and carbon source gas for 30-300 min at a gas flow rate of 100-1000 SCCM, to obtain a phosphorus-carbon metal composite anode material;

[0016] The carbon source gas is one or more of acetylene, methane, ethylene, or ethane.

[0017] Specifically, a method for preparing a phosphorus-carbon metal composite anode material includes the following steps:

[0018] Step S1:

[0019] According to the mass ratio of carbon source compound: activator: molybdenum compound = 100:10-30:5-20, the carbon source compound, activator and molybdenum compound are added to the ball mill and mixed evenly. First, inert gas is introduced to purge the air in the tube, then activation gas is introduced, the temperature is raised to 400-600℃ and held for 0.5-2h, then the activation gas is stopped and the temperature is raised to 700-1000℃ and held for 1-6h to obtain molybdenum-doped porous carbon.

[0020] Step S2:

[0021] Molybdenum-doped porous carbon was transferred to a vacuum reactor. Under a vacuum of 10-100 Pa and a temperature of 400-700 °C, red phosphorus gas and selenium gas (volume ratio: red phosphorus gas: selenium gas = 1-5:1) were introduced at a flow rate of 100-1000 SCCM and mixed for 60-600 min to obtain molybdenum phosphide selenide porous carbon.

[0022] Step S3:

[0023] Molybdenum phosphide selenide porous carbon was transferred to a fluidized bed and deposited at 400-600℃ with a gas flow rate of 100-1000 SCCM, and sulfur vapor was introduced sequentially for 60-600 min and carbon source gas for 30-300 min to obtain a phosphorus-carbon metal composite anode material.

[0024] The technical objective of the second aspect of this invention is to provide a phosphorus-carbon metal composite anode material.

[0025] Furthermore, the phosphorus-carbon metal composite anode material is granular with a particle size between 5-10 μm.

[0026] The technical objective of the third aspect of this invention is to provide an application of a phosphorus-carbon metal composite anode material in the preparation of anode materials for sodium-ion batteries.

[0027] Implementing the embodiments of the present invention will have the following beneficial effects:

[0028] 1) By doping porous carbon with molybdenum, the electronic conductivity of porous carbon materials is improved on the one hand, and the sodium storage capacity of the materials is improved on the other hand. At the same time, the porous carbon structure can reduce the expansion of selenium sulfide during charge and discharge, and improve cycle performance.

[0029] 2) The gas deposition method for reacting metallic selenium with sulfur vapor to generate selenium sulfide has the characteristics of sufficient reaction, high efficiency and good structural stability of the resulting material; and the outer shell is coated with amorphous carbon to reduce the direct contact between the core selenium sulfide and phosphorus sulfide and the electrolyte, thereby reducing side reactions and improving high-temperature storage performance and cycle performance.

[0030] 3) The phosphorus-carbon metal composite anode material of the present invention utilizes molybdenum selenide and phosphorus to improve the specific capacity of the material and utilizes a porous structure to reduce the expansion of molybdenum selenide; at the same time, the sulfur-doped amorphous carbon deposited on the outer shell improves the electronic conductivity of the material. When applied to sodium-ion batteries, it has the advantages of high specific capacity, good rate performance, low expansion, and improved cycle performance.

[0031] 4) This invention reduces phosphorus impedance and improves phosphorus power through the co-deposition of phosphorus and selenium. Elemental selenium and sulfur vapor can also form selenium sulfide, which provides specific capacity; simultaneously, both selenium sulfide and phosphorus can provide specific capacity, and selenium sulfide has better power. This invention also prepares a porous structure by activating pore formation with water vapor, reducing expansion. Attached Figure Description

[0032] 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.

[0033] in:

[0034] Figure 1 The image shows the SEM image of the phosphorus-carbon metal composite anode material prepared in Example 1. Detailed Implementation

[0035] 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.

[0036] Example 1

[0037] This embodiment provides a method for preparing a phosphorus-carbon metal composite anode material, including the following steps:

[0038] Step S1:

[0039] 100g of polyaniline, 20g of zinc carbonate, and 10g of acetylated molybdenum were added to a ball mill and mixed evenly, then added to a tube furnace. First, argon inert gas was introduced to purge the air from the tube. Then, steam activation gas was introduced at a flow rate of 500mL / min, the temperature was raised to 500℃, and held for 1 hour. Afterward, the steam activation gas was stopped, and the temperature was raised to 850℃ and held for 3 hours to obtain molybdenum-doped porous carbon.

[0040] Step S2:

[0041] Molybdenum-doped porous carbon was transferred to a vacuum reactor. Under a vacuum of 50 Pa and a temperature of 600 °C, red phosphorus gas and selenium gas (volume ratio: red phosphorus gas: selenium gas = 3:1) were introduced at a flow rate of 500 SCCM and mixed for 300 min to obtain molybdenum phosphide selenide porous carbon.

[0042] Step S3:

[0043] Molybdenum phosphide selenide porous carbon was transferred to a fluidized bed, and sulfur vapor was introduced at a temperature of 500℃ and a gas flow rate of 500 SCCM for 300 min. Then the temperature was raised to 800℃ and methane gas was introduced at the same flow rate for 150 min for deposition to obtain phosphorus-carbon metal composite anode material.

[0044] Example 2

[0045] This embodiment provides a method for preparing a phosphorus-carbon metal composite anode material, including the following steps:

[0046] Step S1:

[0047] 100g of polythiophene, 10g of sodium carbonate, and 5g of ammonium molybdate were added to a ball mill and mixed evenly, then added to a tube furnace. First, argon inert gas was introduced to purge the air from the tube. Then, carbon dioxide activation gas was introduced at a flow rate of 100mL / min, the temperature was raised to 400℃, and held for 2 hours. Afterward, the carbon dioxide activation gas was stopped, and the temperature was raised to 700℃ and held for 6 hours to obtain molybdenum-doped porous carbon.

[0048] Step S2:

[0049] Molybdenum-doped porous carbon was transferred to a vacuum reactor. Under a vacuum of 10 Pa and a temperature of 400 °C, red phosphorus gas and selenium gas (volume ratio: red phosphorus gas: selenium gas = 1:1) were introduced at a flow rate of 100 SCCM and mixed for 600 min to obtain molybdenum phosphide selenide porous carbon.

[0050] Step S3:

[0051] Porous carbon of molybdenum selenide phosphate was transferred to a fluidized bed, and sulfur vapor was introduced at a temperature of 400℃ and a gas flow rate of 100 SCCM for 600 min. Then the temperature was raised to 700℃ and acetylene gas was introduced at the same flow rate for 300 min for deposition to obtain a phosphorus-carbon metal composite anode material.

[0052] Example 3

[0053] This embodiment provides a method for preparing a phosphorus-carbon metal composite anode material, including the following steps:

[0054] Step S1:

[0055] 100g of melamine, 30g of zinc chloride, and 20g of ammonium dimolybdate were added to a ball mill and mixed evenly, then added to a tube furnace. First, argon inert gas was introduced to purge the air from the tube. Then, sulfur dioxide activation gas was introduced at a flow rate of 800mL / min, the temperature was raised to 600℃, and held for 0.5h. Afterward, the sulfur dioxide activation gas was stopped, and the temperature was raised to 1000℃ and held for 1h to obtain molybdenum-doped porous carbon.

[0056] Step S2:

[0057] Molybdenum-doped porous carbon was transferred to a vacuum reactor. Under a vacuum of 100 Pa and a temperature of 700 °C, red phosphorus gas and selenium gas (volume ratio: red phosphorus gas: selenium gas = 5:1) were introduced at a flow rate of 1000 SCCM and mixed for 60 min to obtain molybdenum phosphide selenide porous carbon.

[0058] Step S3:

[0059] Molybdenum selenide phosphate porous carbon was transferred to a fluidized bed, and sulfur vapor was introduced at a temperature of 600℃ and a gas flow rate of 1000 SCCM for 60 min. Then, the temperature was raised to 1000℃ and ethylene gas was introduced at the same flow rate for 30 min for deposition to obtain a phosphorus-carbon metal composite anode material.

[0060] Comparative Example 1

[0061] This comparative example provides a method for preparing a composite negative electrode material. The difference from Example 1 is that acetylmolybdenum is not added and water vapor activation gas is not introduced in step S1. The rest is the same as in Example 1.

[0062] Comparative Example 2

[0063] This comparative example provides a method for preparing a composite negative electrode material. The difference from Example 1 is that red phosphorus gas is not introduced in step S2, but the rest is the same as in Example 1.

[0064] Comparative Example 3

[0065] This comparative example provides a method for preparing a composite negative electrode material. The difference from Example 1 is that methane gas is not introduced in step S3, but the rest is the same as in Example 1.

[0066] Performance testing:

[0067] 1. SEM testing

[0068] The phosphorus-carbon metal composite anode material prepared in Example 1 was subjected to SEM testing, and the results are as follows: Figure 1 As shown in the figure, the phosphorus-carbon metal composite anode material prepared in Example 1 has a granular structure with uniform size distribution, microporous structure on the surface, and particle size between 5-10 μm.

[0069] 2. Physical and chemical properties and button cell testing

[0070] The tap density, specific surface area, specific capacity, and initial efficiency of the phosphorus-carbon metal composite anode materials prepared in Examples 1-3 and Comparative Examples 1-3 were tested. Test methods: Tests were conducted according to the national standard GB / T 38823-2020 "Silicon-Carbon". Simultaneously, the interlayer spacing of the materials was measured by XRD; and the powder conductivity of the materials was measured using a four-probe analyzer.

[0071] The phosphorus-carbon metal composite anode materials obtained in Examples 1-3 and Comparative Examples 1-3 were assembled into button cells. The preparation method was as follows: binder, conductive agent and solvent were added to the anode material, stirred and slurryed, coated on copper foil, and dried and rolled. The binder used was LA132 binder, the conductive agent was SP, and the negative electrode material was the phosphorus-carbon composite material prepared in Examples 1-3 and Comparative Examples 1-3, respectively. The solvent was double-distilled water, and the ratio was: negative electrode material: SP: LA132: double-distilled water = 94g: 2g: 4g: 220mL, and a negative electrode sheet was prepared. The electrolyte was NaPF6 / EC+DEC (volume ratio 1:1, concentration 1.1mol / L), the counter electrode was a sodium metal sheet, and the separator was a polyethylene (PE) composite membrane. The simulated battery was assembled in an argon-filled glove box, and the electrochemical performance was tested on a Wuhan Landian CT2001A battery tester. The charge / discharge voltage range was 0.00V to 2.0V, and the charge / discharge rate was 0.1C. The rate capability (2C / 0.1C) and cycle performance (0.2C / 0.2C, 100 cycles) of the coin cell were also tested. The test results are shown in Table 1 below.

[0072] Table 1

[0073]

[0074]

[0075] As can be seen from Table 1, compared with Comparative Examples 1-3, the initial discharge capacity, initial efficiency, rate performance, and cycle performance of the phosphorus-carbon metal composite anode materials prepared in Examples 1-3 are significantly improved. This is because, in this invention, the composite material utilizes molybdenum doping to enhance the specific capacity of the material and phosphorus doping to form phosphorus sulfide compounds to enhance the structural stability of the material and improve the cycle performance; selenium sulfide doping provides the conductivity of the material and improves the rate performance.

[0076] 3. Soft-pack battery test:

[0077] The phosphorus-carbon metal composite anode materials from Examples 1-3 and Comparative Examples 1-3 were used as anodes, and anode sheets were prepared by slurry mixing and coating, using layered oxides (NaFe) 1 / 3 Mn1 / 3 Ni 1 / 3 A 2Ah pouch cell was prepared using O2 as the positive electrode, NaPF6 (solvent EC+DEC, volume ratio 1:1, concentration 1.3mol / L) as the electrolyte, and Celegard 2400 as the separator.

[0078] 3.1 High-Temperature Storage Performance Test:

[0079] Test method: The test conditions are as follows: the battery capacity under full charge is tested at 60℃ and recorded as X1. After being placed at 60℃ for 30 days, the battery capacity is tested again and recorded as X2. The charge retention is calculated as X2 / X1*100%. Then, the battery is fully charged to its full state (100% SOC) and its capacity is tested as X3. The recovery capacity is calculated as X3 / X1*100%.

[0080] 3.2 Cyclic performance: 25℃, 1.5-3.95V, 1C / 1C, 500 cycles.

[0081] 3.3 Rate performance: The battery was charged to 3.95C using a constant current and constant voltage rate of 2C + 0.1C. The constant current ratio of the battery was then calculated as 2C constant current capacity / (2C constant current capacity + 0.1C constant voltage capacity). The results are detailed in Table 2.

[0082] Table 2

[0083]

[0084]

[0085] As can be seen from Table 2, the high-temperature storage performance and rate performance of the materials prepared in Examples 1-3 are better than those of the comparative examples. This is because the materials in the examples have high powder conductivity, which can effectively improve the constant current ratio of the materials. At the same time, the surface of the materials in the examples is coated with phosphorus sulfide to reduce the contact between the core material and the electrolyte, reduce side reactions, and improve the high-temperature storage performance.

[0086] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a phosphorus-carbon metal composite anode material, characterized in that, Includes the following steps: A mixture of carbon source compound, activator and molybdenum compound is activated in an activating gas to create pores, thus obtaining molybdenum-doped porous carbon; Molybdenum-doped porous carbon was vapor-deposited in red phosphorus gas and selenium gas to obtain molybdenum selenide phosphide porous carbon. Molybdenum selenide phosphide porous carbon is successively vapor-deposited in sulfur vapor and carbon source vapor to obtain phosphorus-carbon metal composite anode material. Among them, the porous carbon of molybdenum selenide phosphide was subjected to sulfur vapor at a temperature of 400-600℃ and a gas flow rate of 100-1000 SCCM for 60-600 min, after which... Heat to 700℃ and introduce acetylene gas at the same flow rate for 300 minutes. Heat to 800℃ and introduce methane gas at the same flow rate for 150 minutes or Heat to 1000℃, then introduce ethylene gas at the same flow rate for 30 minutes. Deposition was performed to obtain a phosphorus-carbon metal composite anode material; The carbon source compound is one or more of polyaniline, polypyrrole, polythiophene, melamine, or polydopamine; the activator is one or more of zinc carbonate, sodium carbonate, zinc chloride, sodium hydroxide, or potassium hydroxide; the molybdenum compound is one or more of acetylmolybdenum, ammonium molybdate, ammonium dimolybdate, ammonium tetramolybdate, sodium molybdate, or tricarbonyltris(propionitrile)molybdenum. The method for preparing the molybdenum-doped porous carbon includes: mixing a carbon source compound, an activator, and a molybdenum compound; purging the air in the reaction vessel with an inert gas; then introducing an activation gas; heating to 400-600℃ and holding for 0.5-2 hours; stopping the introduction of the activation gas; then heating to 700-1000℃ and holding for 1-6 hours to obtain molybdenum-doped porous carbon. The method for preparing the molybdenum selenide phosphorus porous carbon includes: molybdenum-doped porous carbon is mixed and deposited for 60-600 min under vacuum conditions of 10-100 Pa and temperature of 400-700 °C by introducing red phosphorus gas and selenium gas with a volume ratio of 1-5:1 at a flow rate of 100-1000 SCCM.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the carbon source compound, the activator, and the molybdenum compound is 100:10-30:5-20.

3. The preparation method according to claim 1, characterized in that, The activating gas is one or more of water vapor, carbon dioxide, or sulfur dioxide.

4. A phosphorus-carbon metal composite anode material prepared by any one of claims 1-3.

5. The application of the phosphorus-carbon metal composite anode material according to claim 4 in the preparation of anode materials for sodium-ion batteries.

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