Battery pole piece, phosphate / carbon composite electrode material, and application and manufacturing method thereof

Abstract

This application discloses a battery electrode sheet, a phosphate / carbon composite electrode material, its application, and its preparation method, belonging to the field of new energy materials. The phosphate / carbon composite electrode material is porous and comprises an integral structure with a carbon material as the matrix and a phosphate material as the substrate. The carbon material is a graphite-like nitrogen-doped porous carbon nanosheet, and the phosphate material is a phosphate, which is anchored to the carbon nanosheet in particulate form. This phosphate / carbon composite electrode material has advantages such as good conductivity, high specific capacity, good rate performance, and good cycle performance.

Description

Technical Field

[0001] This application relates to the field of new energy materials technology, specifically to novel carbon nitride-derived porous carbon nanosheets and phosphate composite electrode materials, and more specifically to a battery electrode, a phosphate / carbon composite electrode material, its application and preparation method. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles and electronic products due to their superior energy density and cycle performance. However, the extremely uneven geographical distribution and limited supply of lithium mineral resources pose a significant challenge to the further development of lithium-ion battery technology. Given the abundance of potassium and sodium in the Earth's crust, potassium-ion and sodium-ion batteries have shown promise as potential alternatives to lithium-ion batteries.

[0003] In the comparison, potassium-ion batteries showed several advantages.

[0004] First, due to the physical and chemical properties of alkaline metal lithium itself, lithium-ion batteries have approached the limit of their theoretical energy density.

[0005] Secondly, potassium has a lower redox potential than sodium and a similar potential to lithium, which allows potassium-ion batteries to provide energy density comparable to lithium-ion batteries.

[0006] Furthermore, potassium ions exhibit significantly lower Lewis acidity compared to lithium and sodium ions. This promotes faster ion migration, further enhancing the performance advantages of potassium-ion batteries. Therefore, potassium-ion batteries are expected to become an effective solution for addressing large-scale energy storage challenges and ensuring energy sustainability.

[0007] However, developing a potassium-ion battery with high theoretical capacity, high conductivity, and high cycle stability remains a research challenge and faces many difficulties. Summary of the Invention

[0008] Examples of this application provide a battery electrode, a phosphate / carbon composite electrode material, its application, and a method for its preparation.

[0009] The solution presented in this application is implemented through the following steps.

[0010] In a first aspect, this application discloses a phosphate / carbon composite electrode material.

[0011] The electrode material is a porous, integral structure comprising carbon and phosphoric acid materials; the carbon material forms the matrix, while the phosphoric acid material is an adhering substance on the matrix.

[0012] The carbon material is a nitrogen-doped porous carbon nanosheet in a graphite-like phase, and the phosphoric acid material is a phosphate, which is anchored to the carbon nanosheet in the form of particulate matter.

[0013] Optionally, the carbon material is a derivative formed by denitrification of graphitic carbon nitride (g-C3N4); or, the particulate matter is in the form of nanowires; or, the phosphate / carbon composite electrode material has a specific surface area of ​​260 m² / g; or, the phosphate is antimony phosphate. Nanoscaled particulate matter helps improve ion transport performance, such as shortening the transport distance, thus having a positive effect on capacitance and rate capability.

[0014] In a second aspect, this application discloses a battery electrode containing a phosphate / carbon composite electrode material.

[0015] In a third aspect, this application discloses the application of a phosphate / carbon composite electrode material in a potassium-ion battery, wherein the phosphate / carbon composite electrode material serves as the negative electrode material of the potassium-ion battery.

[0016] Optionally, the method includes: thermally denitrifying a precursor powder obtained by heat treatment and pulverization of urea using zinc powder, followed by acid dezincification, water washing to neutrality, and drying to obtain carbon nanosheets; and

[0017] A precipitate is produced by a hydrothermal reaction using carbon nanosheets, metal chlorides, phosphates, and ethylene glycol, followed by heat treatment of the precipitate.

[0018] Optionally, the method for heat-treating urea includes: heating urea at a preset temperature regime, wherein the temperature regime is 2~10℃·min. -1 The temperature is increased to 500°C to 600°C at a rate of [missing information], and held at that temperature for 3 to 10 hours. Preferably, the heating rate is, for example, 3°C / min. -1 4℃·min -1 5℃·min -1 6℃·min -1 7℃·min -1 8℃·min -1 or 9℃·min -1 The heating temperature can be 510 to 590℃, 520 to 550℃, 520 to 560℃, or 540 to 580℃. The holding time can be controlled at 3 to 4 hours, 5 to 9 hours, 3 to 8 hours, or 5 to 7 hours.

[0019] Alternatively, the heat treatment of urea is carried out by placing the urea in a combustion boat and heating it in a muffle furnace; alternatively, the pulverization operation is carried out by grinding in an agate mortar.

[0020] Optionally, the method of thermally denitrifying the precursor powder using zinc powder includes: mixing the precursor powder with zinc powder and pressing it into tablets, and then calcining it in an inert atmosphere.

[0021] Optionally, the mixing method is grinding, and the tableting pressure is 5 to 20 MPa. For example, the pressure can be 5 to 18 MPa, 11 to 19 MPa, 10 to 16 MPa, 8 to 12 MPa, or 13 to 17 MPa.

[0022] Optionally, the temperature regime for the calcination process is: 5~10℃·min -1 The temperature is increased to 700°C to 850°C at a rate of [missing information], and held at that temperature for 2 to 6 hours. Preferably, the heating rate is, for example, 6°C / min. -1 7℃·min -1 8℃·min -1 The heating temperature can be 720 to 840℃, 710 to 800℃, 750 to 820℃, or 760 to 810℃. The holding time can be controlled to be 2 to 5 hours, 3 to 4 hours, or 5 to 6 hours.

[0023] Optionally, the metal chloride is used at a concentration of 0.02~0.05 mol L. -1 It is provided in the form of SbCl3 or BiCl3. Preferably, the concentration can also be from 0.02 to 0.03 mol L. -1 0.04 to 0.05 mol L -1 Or 0.03 to 0.04 mol L -1 、.

[0024] Optionally, the phosphate is used at a concentration of 0.05~0.1 mol L. -1 It is provided in the form of NH4H2PO4 or NaH2PO4. Preferably, the concentration can also be from 0.05 to 0.07 mol L. -1 0.06 to 0.08 mol L -1 Or 0.07 to 0.09 mol L -1 0.09 to 0.1 mol L -1 、.

[0025] Optionally, a 100mL hydrothermal reactor is used in the hydrothermal reaction process, with 60-150g of carbon nanosheets and 60mL of ethylene glycol. The amount of carbon nanosheets can also be 60-70g, 65-90g, 80-100g, 90-110g, or 120-140g.

[0026] Optionally, carbon nanosheets, metal chlorides, phosphates, and ethylene glycol are ultrasonically dispersed under water bath heating conditions at 50°C-70°C to form a dispersion, and the dispersion is used for hydrothermal reaction.

[0027] Optionally, the hydrothermal reaction temperature is 160℃~200℃, and the reaction time is 2 hours to 24 hours. Preferably, the hydrothermal reaction temperature is 160 to 180℃, or 170℃~180℃, and the reaction time is 5 hours to 10 hours.

[0028] Optionally, the heat treatment of the precipitate is annealing.

[0029] Optionally, the annealing atmosphere is nitrogen or argon.

[0030] Optionally, the annealing temperature is 500~600℃, and the annealing time is 4~10h. Preferably, the annealing temperature is 510~580℃, or 520-560℃, or 530-590℃; correspondingly, the annealing time can be 5~9h, 6-8h, 7 to 10h, or 4 to 8h.

[0031] Optionally, the method for preparing the battery electrode includes:

[0032] Provides phosphate / carbon composite electrode materials, or phosphate / carbon composite electrode materials obtained by methods for preparing phosphate / carbon composite electrode materials; and

[0033] A slurry containing phosphate / carbon composite electrode material, CMC2200, conductive carbon black, and NMP solvent is coated onto copper foil. CMC2200 is sodium carboxymethyl cellulose, used as a binder or thickener.

[0034] Optionally, the mass ratio of the phosphate / carbon composite electrode material to CMC2200 and conductive carbon black is 7:1.5:1.5, 7:2:1, or 8:1:1.

[0035] The phosphate / carbon composite electrode material described in this application has the advantages of high conductivity and high specific capacity, and the raw materials are inexpensive and readily available, the preparation process is simple, and the operation is highly controllable. Potassium-ion batteries made using this composite electrode material can exhibit excellent cycle and rate performance. Attached Figure Description

[0036] The accompanying drawings described herein are provided to further illustrate the present application and form part of this application. The illustrative embodiments and descriptions of this application are used to explain the present application and do not constitute an undue limitation thereof.

[0037] Figure 1 The XRD pattern of the SbPO4 / NC composite material prepared in Example 1 of this application;

[0038] Figure 2 This is a SEM image of the SbPO4 / NC composite material prepared in Example 1 of this application;

[0039] Figure 3 The SbPO4 / NC composite material prepared in Example 1 of this application was used as a negative electrode material for a potassium-ion battery, with a voltage range of 0.01–3.0 V and a current density of 200 mA g. -1 The cyclic performance test diagram under the given conditions.

[0040] Figure 4 The rate performance test diagram of the SbPO4 / NC composite material prepared in Example 1 of this application as a negative electrode material for potassium-ion batteries. Detailed Implementation

[0041] Due to the high cost of lithium-ion batteries and the fact that their performance is difficult to improve further, this application proposes a phosphate / carbon composite electrode material that can be used to manufacture potassium-ion batteries. This composite material is a metal phosphate-based material and is used as the negative electrode material for potassium-ion batteries.

[0042] From a microstructural perspective, phosphate / carbon composite electrode materials have a porous structure, which allows for rapid migration of charges and ions, thereby alleviating to some extent the volume expansion problem caused by cycling in secondary batteries made from them.

[0043] Especially considering the relatively large radius of potassium ions (compared to lithium-ion batteries), the migration, insertion, and extraction of potassium ions are quite challenging. During charge and discharge, the expansion coefficient is large, and the negative electrode is prone to pulverization, leading to poor cycle performance. Furthermore, potassium ion kinetics are slow, and the diffusion coefficient is small, resulting in poor rate performance. The composite material of phosphate and carbon materials proposed in this application can effectively solve these problems.

[0044] Furthermore, this composite electrode material enables the negative electrode material prepared based on it to have better electrochemical performance, thus making it more suitable for potassium-ion batteries.

[0045] Specifically, the carbon matrix in the composite electrode material contains macropores and mesopores.

[0046] The pore size of the macropores is 100-200 nm, such as 100 nm, 160 nm, 170 nm, 180 nm, 190 nm or 200 nm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] The pore size of the mesopores is 5-15nm, such as 5nm, 8nm, 10nm, 12nm or 15nm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] Furthermore, the phosphate in the composite electrode material is particulate. Preferably, the particulate is a nanowire structure. For example, the phosphate nanowires are short rods with a diameter of 10-50 nm and a length of 0.2-1 μm. Exemplarily, the nanowires have diameters of 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm, and lengths of 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, or 1 μm, but are not limited to the listed values; other unlisted values ​​within this range, or values ​​defined between any two, are also applicable.

[0049] In this application, one advantage of using phosphates (such as K3PO4) is that:

[0050] It is an excellent ionic conductor that can significantly improve the electrical conductivity of materials.

[0051] Furthermore, K3PO4 is a product of SbPO4 recycling, thus offering low cost. K3PO4 is also non-toxic, making it eco-friendly, and it boasts advantages such as high abundance and high crystallinity. These factors make metal phosphates a novel energy storage electrode material and can improve the cycle stability of potassium-ion batteries manufactured based on such materials during operation.

[0052] Furthermore, phosphates also possess an open framework structure, in which large and stable PO4 groups are present. 3- Anions can cause a much smaller volume change than alloy anodes during battery operation, avoiding more side reactions and thus improving cycle stability.

[0053] Antimony phosphate, with its rapid ion transport capabilities and high structural durability, holds great potential for application in alkali metal ion batteries. Furthermore, the antimony ions in antimony phosphate crystals possess lone pairs of electrons, thus exhibiting better conductivity. More importantly, phosphates are also ionic conductors, effectively lowering the diffusion barrier of sodium ions and promoting reaction kinetics.

[0054] In summary, metal phosphates have a unique structure, low operating voltage, are environmentally friendly, and have high theoretical capacity.

[0055] In particular, this application also combines carbon materials with metal phosphates, which can suppress the large volume change and low conductivity of the negative electrode material made based on the above materials during actual potassium storage, thereby improving the capacity decay problem of the corresponding potassium-ion battery during charging and discharging cycles.

[0056] Combining the porous structure of the carbon matrix with the nanowire structure of phosphate, the phosphate / carbon composite material possesses a high specific surface area, thus exhibiting a large number of reactive sites. Simultaneously, it provides an ideal pathway for ion migration, thereby offering a high ion mobility (0.1 × 10⁻⁶). -10 ~5×10 -10 cm 2 s -1 For example, the specific surface area of ​​this composite material is 120-300 m². 2 g -1 For example, including 120m 2 g -1 130m 2 g -1 160m 2 g -1 180m 2 g -1 or 300m 2 g -1 This applies to, but is not limited to, the listed values; other unlisted values ​​within this range also apply.

[0057] In particular, the carbon material in the composite electrode is a nitrogen-doped porous carbon nanosheet in a graphite-like phase.

[0058] Specifically, the carbon material is a derivative formed by denitrification of graphitic carbon nitride (g-C3N4). The nitrogen-doped porous carbon derived from g-C3N4 contains a high pyrrole N content, reaching 7.81 at%. Since pyrrole N has strong electrostatic repulsion, it has a certain influence on the expansion of the carbon interlayer spacing, which will affect the subsequent potassium storage performance.

[0059] Furthermore, N doping can modulate the structure of the carbon layer, optimize its electronic conductivity and surface hydrophilicity, and thus promote K... + Insertion and adsorption. The robust porous carbon matrix effectively alleviates the poor conductivity and volume expansion problems of antimony phosphate, thereby providing better cycling performance.

[0060] Based on the ease of implementation by those skilled in the art, this disclosure also provides a method for preparing phosphate / carbon composite electrode materials.

[0061] Furthermore, the method includes:

[0062] Step S1: The precursor powder obtained by heat treatment and pulverization of urea is thermally denitrified using zinc powder, then dezincified by acid solution, washed with water until neutral, and dried to obtain carbon nanosheets.

[0063] Step S2: A hydrothermal reaction is carried out using carbon nanosheets, metal chlorides, phosphates and ethylene glycol to produce a precipitate, and the precipitate is then heat-treated.

[0064] A more specific example is as follows:

[0065] (1) Place urea into a combustion boat, heat it in a muffle furnace and then cool it. Grind it into powder with an agate mortar to obtain g-C3N4 precursor for further use.

[0066] (2) Synthesis of porous carbon nanosheets: The sample described in step (1) was mixed with zinc powder and placed in a tube furnace for high-temperature denitrification treatment to obtain a black solid. The zinc powder was removed with hydrochloric acid, washed with deionized water until neutral, and dried to obtain carbon nanosheets.

[0067] (3) The carbon nanosheets described in step (2) are mixed with metal chloride, phosphate, and ethylene glycol, and then transferred to a hydrothermal reactor for hydrothermal reaction. The precipitate is collected and processed, and then heat-treated to obtain the phosphate / carbon composite electrode material.

[0068] Further, the composite electrode material, CMC2200, and conductive carbon black described in step (3) are mixed in a mass ratio of 7:1.5:1.5 (or 7:2:1, or 8:1:1, etc.) to obtain a slurry, which is then coated onto copper foil to obtain the negative electrode. The negative electrode is then cut into sheets, assembled into a battery, and its electrochemical performance is tested.

[0069] In particular, due to their ideal capacitance performance, the above materials can also be considered for use in the manufacture of supercapacitors.

[0070] The following are several specific examples of the application of the aforementioned composite materials in batteries. The batteries are, for example, button cells; and their typical structures include, for example, a positive electrode shell, a positive electrode sheet, a separator, a negative electrode sheet, a gasket, a spring sheet, and a negative electrode shell.

[0071] For any specific conditions not specified in the examples, follow standard conditions or the manufacturer's recommendations. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0072] Example 1

[0073] 1. Place urea into the combustion boat and heat it in a muffle furnace at 5°C / min. -1 After heating to 550℃ and holding for 5 hours, the mixture was cooled and ground into powder using an agate mortar to obtain the g-C3N4 precursor for further use.

[0074] 2. Place the sample from step (1) and zinc powder in a mortar at a mass ratio of 1:2, grind for 1 hour, mix, and then press into tablets using a pressure of 10 MPa. Place the pressed tablets into a tube furnace and heat under argon protection at 5°C·min. -1The temperature was raised to 750°C and held for 2 hours to obtain a black solid. Excess zinc powder was removed with hydrochloric acid, and the solid was washed with deionized water until neutral. After drying, carbon nanosheets were obtained. The nitrogen content of the carbon nanosheets was 17.92%, of which pyridine nitrogen accounted for 53.03%.

[0075] 3. Mix the carbon nanosheets (90 mg) from step (2) with 0.025 mol L -1 SbCl3, 0.075 mol L -1 NH4H2PO 4、 After mixing with 60 mL of ethylene glycol, the mixture is transferred to a hydrothermal reactor, heated to 180 °C and held for 12 h. The precipitate is collected and processed, and then the processed precipitate is placed in argon gas and annealed at 550 °C for 6 h to obtain the phosphate / carbon composite electrode material.

[0076] (4) Mix the composite electrode material, CMC2200 and conductive carbon black in step (3) in NMP solvent at a ratio of 7:1.5:1.5 to obtain a slurry. Coat the slurry onto the copper foil to obtain the negative electrode.

[0077] (5) Cut the negative electrode from step (4) into pieces, install them into a battery, and test the electrochemical performance.

[0078] Figure 1 The image shows the XRD pattern of the SbPO4 / NC composite material prepared in Example 1. The horizontal axis represents the diffraction angle (2Theta), and the vertical axis represents the diffraction peak intensity (Intensity).

[0079] Figure 2 This is a SEM image of the SbPO4 / NC composite material prepared in Example 1.

[0080] Figure 3 The SbPO4 / NC composite material prepared in Example 1 was used as the anode material for a potassium-ion battery, and it performed well in the voltage range of 0.01–3.0 V and the current density of 200 mA g. -1 The graph shows the cyclic performance test under the given conditions. The horizontal axis represents the number of cycles (CycleNumber), the left vertical axis represents the specific capacitance (Specific Capacity), and the right vertical axis represents the coulombic efficiency (Coulombicefficiency).

[0081] Figure 4 The graph shows the rate performance of the SbPO4 / NC composite material prepared in Example 1 as a potassium-ion battery anode material. The horizontal axis represents the number of cycles, and the vertical axis represents the specific capacitance.

[0082] Example 2

[0083] 1. Place urea into the combustion boat and heat it in a muffle furnace at 10°C / min. -1 After heating to 550℃ and holding for 3 hours, the mixture was cooled and ground into powder using an agate mortar to obtain the g-C3N4 precursor for further use.

[0084] 2. Place the sample from step (1) and zinc powder in a mortar at a mass ratio of 1:1, grind for 1 hour, mix, and then press into tablets using a pressure of 10 MPa. Place the pressed tablets into a tube furnace and heat under argon protection at 5°C·min. -1 The temperature was raised to 750°C and held for 2 hours to obtain a black solid. Excess zinc powder was removed with hydrochloric acid, and the solid was washed with deionized water until neutral. After drying, carbon nanosheets were obtained. The nitrogen content of the carbon nanosheets was 18.79%, of which pyridine nitrogen accounted for 41.70%.

[0085] 3. Mix the carbon nanosheets (90 mg) from step (2) with 0.025 mol L -1 SbCl3, 0.075 mol L -1 After mixing NH4H2PO4 and 60mL of ethylene glycol, the mixture is transferred to a hydrothermal reactor, heated to 180℃ and held for 12h. The precipitate is collected and processed, and then the processed precipitate is placed in argon gas and annealed at 550℃ for 6h to obtain the phosphate / carbon composite electrode material.

[0086] (4) The composite electrode material from step (3) is mixed with CMC2200 and conductive carbon black in NMP solvent at a ratio of 7:1.5:1.5 to obtain a slurry. This slurry is then coated onto copper foil to obtain the negative electrode.

[0087] (5) Cut the negative electrode from step (4) into pieces, install them into a battery, and test the electrochemical performance.

[0088] Example 3

[0089] 1. Place urea into the combustion boat and heat it in a muffle furnace at 5 °C·min. -1 After heating to 550 ℃ and holding for 5 hours, the mixture was cooled and ground into powder using an agate mortar to obtain the g-C3N4 precursor for further use.

[0090] 2. Place the sample from step (1) and zinc powder in a mortar at a mass ratio of 1:3, grind for 1 hour, mix, and then press into tablets using a pressure of 10 MPa. Place the pressed tablets into a tube furnace and heat under argon protection at 5°C·min. -1 The temperature was raised to 700°C and held for 2 hours to obtain a black solid. Excess zinc powder was removed with hydrochloric acid, and the solid was washed with deionized water until neutral. After drying, carbon nanosheets were obtained. The nitrogen content of the carbon nanosheets was 20.52%, of which pyridine nitrogen accounted for 52.74%.

[0091] 3. Mix the carbon nanosheets (90 mg) from step (2) with 0.025 mol L-1 SbCl3, 0.075 mol L -1 After mixing NH4H2PO4 and 60mL of ethylene glycol, the mixture is transferred to a hydrothermal reactor, heated to 180℃ and held for 12h. The precipitate is collected and processed, and then placed in argon gas and annealed at 550℃ for 6h to obtain the phosphate / carbon composite electrode material.

[0092] (4) The composite electrode material from step (3) is mixed with CMC2200 and conductive carbon black in NMP solvent at a ratio of 7:1.5:1.5 to obtain a slurry. This slurry is then coated onto copper foil to obtain the negative electrode.

[0093] (5) Cut the negative electrode from step (4) into pieces, install them into a battery, and test the electrochemical performance.

[0094] Example 4

[0095] 1. Place urea into the combustion boat and heat it in a muffle furnace at 5 °C·min. -1 After heating to 550 ℃ and holding for 5 hours, the mixture was cooled and ground into powder using an agate mortar to obtain the g-C3N4 precursor for further use.

[0096] 2. Place the sample from step (1) and zinc powder in a mortar at a mass ratio of 1:2, grind for 1 hour, mix, and then press into tablets using a pressure of 10 MPa. Place the pressed tablets into a tube furnace and heat under argon protection at 5°C·min. -1 The temperature was raised to 750°C and held for 2 hours to obtain a black solid. Excess zinc powder was removed with hydrochloric acid, and the solid was washed with deionized water until neutral. After drying, carbon nanosheets were obtained. The nitrogen content of the carbon nanosheets was 17.92%, of which pyridine nitrogen accounted for 53.03%.

[0097] 3. Mix the carbon nanosheets (90 mg) from step (2) with 0.025 mol L -1 BiCl3, 0.075 mol L -1 After mixing NH4H2PO4 and 60mL of ethylene glycol, the mixture is transferred to a hydrothermal reactor, heated to 180℃ and held for 12h. The precipitate is collected and processed, and then the processed precipitate is placed in argon gas and annealed at 550℃ for 6h to obtain the phosphate / carbon composite electrode material.

[0098] (4) The composite electrode material from step (3) is mixed with CMC2200 and conductive carbon black in NMP solvent at a ratio of 7:1.5:1.5 to obtain a slurry. This slurry is then coated onto copper foil to obtain the negative electrode.

[0099] (5) Cut the negative electrode from step (4) into pieces, install them into a battery, and test the electrochemical performance.

[0100] Example 5

[0101] 1. Place urea into the combustion boat and heat it in a muffle furnace at 5°C / min. -1 After heating to 550℃ and holding for 5 hours, the mixture was cooled and ground into powder using an agate mortar to obtain the g-C3N4 precursor for further use.

[0102] 2. Place the sample from step (1) and zinc powder in a mortar at a mass ratio of 1:2, grind for 1 hour, mix, and then press into tablets using a pressure of 10 MPa. Place the pressed tablets into a tube furnace and heat under argon protection at 5°C·min. -1 The temperature was raised to 750°C and held for 2 hours to obtain a black solid. Excess zinc powder was removed with hydrochloric acid, and the solid was washed with deionized water until neutral. After drying, carbon nanosheets were obtained. The nitrogen content of the carbon nanosheets was 17.92%, of which pyridine nitrogen accounted for 53.03%.

[0103] 3. Mix the carbon nanosheets (90 mg) from step (2) with 0.025 mol L -1 SbCl3, 0.075 mol L -1 After mixing NaH2PO4 and 60 mL of ethylene glycol, the mixture was transferred to a hydrothermal reactor and heated to 180 °C for 20 h. The precipitate was collected and processed, and then the processed precipitate was placed in argon gas and annealed at 550 °C for 6 h to obtain the phosphate / carbon composite electrode material.

[0104] (4) The composite electrode material from step (3) is mixed with CMC2200 and conductive carbon black in NMP solvent at a ratio of 7:1.5:1.5 to obtain a slurry. This slurry is then coated onto copper foil to obtain the negative electrode.

[0105] (5) Cut the negative electrode from step (4) into pieces, install them into a battery, and test the electrochemical performance.

[0106] Example 6

[0107] 1. Place urea into the combustion boat and heat it in a muffle furnace at 5°C / min. -1 After heating to 550℃ and holding for 5 hours, the mixture was cooled and ground into powder using an agate mortar to obtain the g-C3N4 precursor for further use.

[0108] 2. Place the sample from step (1) and zinc powder in a mortar at a mass ratio of 1:2, grind for 1 hour, mix, and then press into tablets using a pressure of 10 MPa. Place the pressed tablets into a tube furnace and heat under argon protection at 5°C·min. -1 The temperature was raised to 750°C and held for 2 hours to obtain a black solid. Excess zinc powder was removed with hydrochloric acid, and the solid was washed with deionized water until neutral. After drying, carbon nanosheets were obtained. The nitrogen content of the carbon nanosheets was 17.92%, of which pyridine nitrogen accounted for 53.03%.

[0109] 3. Mix the carbon nanosheets (90 mg) from step (2) with 0.025 mol L -1 SbCl3, 0.075 mol L -1 After mixing NH4H2PO4 and 60mL of ethylene glycol, the mixture is transferred to a hydrothermal reactor, heated to 180℃ and held for 12h. The precipitate is collected and processed, and then the processed precipitate is placed in argon gas and annealed at 600℃ for 10h to obtain the phosphate / carbon composite electrode material.

[0110] (4) The composite electrode material from step (3) is mixed with CMC2200 and conductive carbon black in NMP solvent at a ratio of 7:1.5:1.5 to obtain a slurry. This slurry is then coated onto copper foil to obtain the negative electrode.

[0111] (5) Cut the negative electrode from step (4) into pieces, install them into a battery, and test the electrochemical performance.

[0112] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0113] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A phosphate / carbon composite electrode material, characterized by, The electrode material is porous and comprises an integral structure of carbon material and phosphoric acid material, wherein the carbon material is the matrix and the phosphoric acid material is an adhering substance on the matrix. The carbon material is a nitrogen-doped porous carbon nanosheet in a graphite-like phase. The carbon material is a derivative formed by denitrification of graphite-like carbon nitride (g-C3N4) and contains pyrrole nitrogen that expands the carbon interlayer spacing. The phosphoric acid material is antimony phosphate, and the antimony phosphate is anchored to the derivative in the form of nanowires. The specific surface area of ​​the phosphate / carbon composite electrode material is 260 m² / g.

2. A battery electrode sheet, characterized by, The material contains the phosphate / carbon composite electrode material as described in claim 1.

3. Use of the phosphate / carbon composite electrode material according to claim 1 in a potassium-ion battery, characterized in that: The phosphate / carbon composite electrode material is used as the negative electrode material for potassium-ion batteries.

4. A method of preparing the phosphate / carbon composite electrode material as claimed in claim 1, characterized in that, The method includes: Carbon nanosheets were obtained by thermally denitrifying urea precursor powder obtained through heat treatment and pulverization using zinc powder, followed by acid dezincification, water washing to neutrality, and drying. A precipitate is produced by a hydrothermal reaction using carbon nanosheets, metal chlorides, phosphates, and ethylene glycol, followed by heat treatment of the precipitate.

5. The method of claim 4, wherein the method is characterized by, The method for heat-treating urea includes: heating urea at a preset temperature regime, wherein the temperature regime is 2~10℃·min. -1 The temperature is rapidly increased to 500°C to 600°C and held at that temperature for 3 to 10 hours.

6. The method of claim 4, wherein the phosphate / carbon composite electrode material is prepared by the process of claim 4. The method for thermal denitrification of precursor powder using zinc powder includes: mixing the precursor powder with zinc powder and pressing it into tablets, and then calcining it in an inert atmosphere; The mixing method is grinding, and the tableting pressure is 5 to 20 MPa; The temperature regime of the calcination process is: temperature increase at a rate of 5 to 10 °C·min -1 to 700 to 850 °C, and holding at this temperature for 2 to 6 hours.

7. The method for preparing phosphate / carbon composite electrode material according to claim 4, characterized in that, The metal chloride is provided in the form of SbCl3or BiCl3in a concentration of 0.02 to 0.05 mol L -1 - 0.05 mol L phosphate is provided in the form of NH4H2PO4or NaH2PO4at a concentration of 0.05 to 0.1 mol L -1 ; The hydrothermal reaction process uses a 100mL hydrothermal reactor, with 60~150g of carbon nanosheets and 60mL of ethylene glycol. Carbon nanosheets, metal chlorides, phosphates and ethylene glycol are ultrasonically dispersed under water bath heating conditions at 50℃-70℃ to form a dispersion, and the dispersion is used to carry out a hydrothermal reaction. The hydrothermal reaction temperature is 160℃~200℃, and the reaction time is 2 hours to 24 hours.

8. The method for preparing phosphate / carbon composite electrode material according to claim 4, characterized in that, The heat treatment method for the precipitate is annealing; The annealing atmosphere is nitrogen or argon; The annealing temperature is 500~600℃, and the annealing time is 4~10h.

9. A method of preparing a battery electrode sheet, characterized by, include: Provides the phosphate / carbon composite electrode material as described in claim 1, or the phosphate / carbon composite electrode material obtained by implementing the method for preparing the phosphate / carbon composite electrode material according to any one of claims 4-8; as well as The slurry, which is a mixture of the phosphate / carbon composite electrode material, CMC2200, conductive carbon black, and NMP solvent, is coated onto a copper foil.

10. The method of claim 9, wherein, The mass ratio of phosphate / carbon composite electrode material to CMC2200 and conductive carbon black is 7:1.5:1.5, 7:2:1, or 8:1:1.

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