Phosphated coated mesoporous v2o5 particles / graphene composite electrode material, preparation method and application thereof

Abstract

This invention relates to the field of electrode material preparation technology, specifically to a phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material, its preparation method, and its application, suitable for lithium-ion battery cathodes. The preparation method includes the following steps: preparing a graphene oxide reverse micelle dispersion; mixing a surfactant, co-surfactant, organic solvent, and deionized water at a mass ratio of 1:(0.5~2):(5~20):(0.5~1), stirring to form a homogeneous mixture; reacting to prepare a composite precursor; washing, drying, and calcining. This method achieves mesoporous construction, in-situ growth of an amorphous phosphating coating layer, B-O-V / C covalent bond interface anchoring, and uniform composite of V₂O₅ and graphene in a single reaction system in one step, significantly improving the material's reversible specific capacity, cycle stability, and rate performance.

Description

Technical Field

[0001] This invention belongs to the field of electrode material preparation technology, specifically relating to a phosphating-coated mesoporous V2O5 particle / graphene composite electrode material, its preparation method and application, which is suitable for lithium-ion battery cathodes. Background Technology

[0002] Lithium-ion batteries, with their high energy density and long cycle life, have become core energy storage devices in new energy vehicles, energy storage systems, and portable electronic products. Their performance is highly dependent on the specific capacity and operating voltage of the cathode material. Among many cathode materials, vanadium pentoxide (V₂O₅) has a high theoretical specific capacity, achieving up to 443 mAh / g through a three-electron transfer process. It also possesses a good layered structure and electrochemical activity, with a specific capacity far exceeding that of commonly used commercially available intercalated cathode materials such as lithium cobalt oxide and lithium iron phosphate, demonstrating enormous potential in the energy storage field. However, pure V₂O₅ has significant limitations: firstly, its electronic conductivity is low, only 10⁻⁶. -4 ~10 -2 First, the reduced capacity (S / cm) leads to impeded electron transport and poor rate performance. Second, significant volume expansion occurs during charging and discharging, causing structural collapse and poor cycle stability. Third, particles are prone to agglomeration, resulting in low utilization of active sites and difficulty in fully releasing specific capacity. Fourth, severe interfacial side reactions such as electrolyte erosion and vanadium dissolution occur during charging and discharging, and dissolved vanadium ions migrate to the electrolyte and react with the negative electrode, significantly reducing the battery's cycle stability.

[0003] To address the aforementioned shortcomings of pure V₂O₅, the industry commonly employs modification strategies such as morphology control, elemental doping, surface coating, and carbon material composites. Among these, the most effective is the construction of V₂O₅ / graphene composite systems. However, existing V₂O₅ / graphene composite systems suffer from three core defects, significantly falling short of the demands for high-performance applications: ① Poor interfacial bonding stability: V₂O₅ and graphene rely solely on physical adsorption or van der Waals forces for bonding, lacking selective chemical bonding and anchoring, resulting in uneven particle loading and easy delamination and loss of active sites during cycling; ② Inefficient coating modification: Coating materials are mostly carbon or metal oxides, failing to simultaneously improve conductivity and inhibit vanadium dissolution. Furthermore, the coating layers are often crystalline or non-dense structures, prone to failure; ③ Lack of process synergy: The fragmented process of "synthesizing V₂O₅ first and then modifying in steps" is often employed, resulting in low efficiency and high cost. It is impossible to simultaneously achieve multi-functional integration such as mesoporous construction, surface coating, and interfacial strengthening in a single system, leading to poor modification effects. For example, patent CN109830666A discloses a three-dimensional nanoflower structure to increase the vanadium pentoxide cathode material. Although this increases the specific surface area and improves lithium-ion transport, it does not incorporate graphene, relying solely on the substrate's conductivity, resulting in limited improvement in conductivity. Furthermore, it lacks coating and mesoporous control, leading to poor structural stability. Another example is patent CN109817943A, which utilizes porous graphene foam to increase V₂O₅ loading and shorten lithium-ion transport distance, exhibiting excellent electrochemical performance. However, the crystalline carbon coating layer is prone to rupture during charge and discharge, and the absence of a mesoporous structure to mitigate volume expansion limits the improvement in cycle stability. Yet another example is patent CN106784738A, which prepares a magnesium-doped vanadium pentoxide / carbon composite cathode material. 2+ Increasing the interlayer spacing of V2O5 and inhibiting its dissolution with a carbon matrix improves cycle stability; however, the amorphous carbon substrate cannot form a continuous conductive network, and precise control of the V2O5 mesoporous structure has not been achieved. In summary, existing technologies cannot simultaneously overcome the three core challenges of "poor interfacial bonding stability, inefficient coating modification, and lack of process synergy," resulting in reversible specific capacity, cycle stability, and rate performance that consistently fail to meet the requirements for high-performance lithium-ion batteries.

[0004] Therefore, there is an urgent need to develop a method for preparing high-performance V2O5 / graphene composite electrode materials that is simple to operate, highly controllable, and combines "strong interface bonding, synergistic modification functions, and efficient process integration". Summary of the Invention

[0005] To address the shortcomings of existing technologies, the main objective of this invention is to provide a phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material, its preparation method, and its applications. This invention specifically proposes an innovative scheme of "reverse micelle-mediated mesoporous control + amorphous phosphating coating for dense protection + BOV / C covalent bond interface reinforcement + graphene continuous conductive network construction." Through a single reaction system, it achieves mesoporous construction, in-situ growth of the amorphous phosphating coating layer, BOV / C covalent bond interface anchoring, and uniform composite of V₂O₅ and graphene in one step. The amorphous phosphating coating layer solves interfacial side reactions such as vanadium dissolution, and covalent bonds overcome particle exfoliation and agglomeration challenges. This one-step process overcomes process fragmentation defects and achieves synergistic effects of multiple modified functions. The key innovation of this invention lies in the simultaneous introduction of hydroxyl-containing borate ester coupling agents through the spatial confinement effect of a reverse micelle microreactor, enabling the simultaneous one-step realization of "precise construction of V₂O₅ mesoporous structure and formation of amorphous phosphating coating, controllable loading of mesoporous V₂O₅ on the graphene surface, and strengthening of the BOV / C covalent bond interface" without the need for multi-step modification. The phosphating coating prepared by this invention is amorphous vanadium phosphorus oxide (V₂O₅). x P y O z Its advantages are reflected in two aspects: First, it is a dense and uniform coating layer. Its dense structure tightly wraps the mesoporous V2O5 primary particles, which not only effectively isolates the electrolyte corrosion physically, but also significantly inhibits interfacial side reactions such as HF corrosion and vanadium ion dissolution due to its excellent chemical stability, thereby achieving efficient and stable protection of active materials. Second, through strong VOP covalent bonding with the matrix, it endows the coating layer with excellent interfacial bonding force and toughness, which can adapt to volumetric strain during long cycles and maintain structural integrity, thereby ensuring the durability and robustness of the protective effect.

[0006] This invention achieves a comprehensive improvement in material performance through the synergistic effect of four major functions: First, the reverse micelle method provides a confined microreactor, enabling the simultaneous integration of mesoporous structure construction, in-situ growth of the phosphating coating layer, and uniform composite of V2O5 particles / graphene, effectively solving the problem of lack of synergy in existing processes; Second, hydroxyl-containing borate ester coupling agents mediate the formation of BOV / C covalent bonds at the interface between V2O5 particles and graphene, firmly anchoring V2O5 particles and graphene through chemical bonds, which, unlike the physical bonding of traditional methods, significantly improves the interfacial bonding stability and overcomes the pain points of particle delamination and agglomeration during cycling; Third, graphene constructs a continuous two-dimensional conductive network, specifically addressing the low electronic conductivity of V2O5; Fourth, the amorphous phosphating coating layer plays a highly efficient protective role, inhibiting interfacial side reactions such as vanadium dissolution. These four functions work together to significantly improve the material's reversible specific capacity, cycling stability, and rate performance.

[0007] To solve at least one of the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] According to one aspect of the present invention, a method for preparing phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material by reverse micelle method is provided, comprising the following steps:

[0009] Preparation of graphene oxide reverse micelle dispersion: A surfactant, co-surfactant, organic solvent, and deionized water were mixed at a mass ratio of 1:(0.5~2):(5~20):(0.5~1) and stirred to form a homogeneous mixture. Then, graphene oxide and a hydroxyl-containing borate ester coupling agent were added to the mixture. The mass ratio of graphene oxide to the mixture was 1:(50~300), and the mass ratio of the coupling agent to graphene oxide was 1:(10~30). The mixture was ultrasonically dispersed to form a homogeneous graphene oxide reverse micelle dispersion. Mechanism of this step: The surfactant self-assembles at the oil-water interface, with the hydrophobic end facing the oil phase and the hydrophilic end encapsulating a trace amount of water phase to form a "water core" microreactor, constituting a mesoporous template. Graphene oxide is uniformly dispersed in the reverse micelle water core and at the oil-water interface. The hydroxyl groups of the coupling agent undergo a dehydration condensation reaction with the hydroxyl groups on the surface of graphene oxide, laying the chemical foundation for the subsequent formation of BOV / C covalent bonds.

[0010] Preparation of the composite precursor by reaction: Under stirring conditions, add 0.1~0.5 mol / L vanadium source solution to the above dispersion, with a molar ratio of vanadium source to graphene oxide of (5~20):1. Adjust the pH of the system to 2.5~3.0, raise the temperature to 30~90℃, and stir for 4~24 hours. Add phosphorus source solution and continue stirring for 4~8 hours. Mechanism of this step: First, after the vanadium source solution enters the reverse micelle water core, it undergoes a hydrolysis reaction in an acidic microenvironment to generate V2O5 hydrate crystal nuclei. At the same time, the borate ester group coordinates with the oxygen ions on the surface of the V2O5 crystal nuclei to form BOV / C covalent bonds, firmly anchoring the V2O5 crystal nuclei to the graphene surface, thus achieving interface strengthening. The mesoporous template of the surfactant restricts the growth of crystal nuclei, precisely constructing a mesoporous structure. After the phosphorus source is added, under the confinement effect of the reverse micelle water core, the phosphorus source undergoes a co-precipitation reaction with the vanadium species on the surface of the V2O5 precursor to form a continuous and dense amorphous vanadium phosphorus oxide gel precursor (i.e., phosphating coating precursor); this precursor will solidify into an amorphous phosphating coating layer under subsequent calcination conditions.

[0011] Washing, drying, and calcination: The composite precursor was washed clean with organic solvents and deionized water alternately, and then vacuum dried. It was then calcined in a tube furnace at an air atmosphere at a heating rate of 5°C / min to 400-600°C for 2-4 hours. The furnace atmosphere was then switched to an inert atmosphere (nitrogen or argon), and calcination continued for another 2-4 hours. After natural cooling, the phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material was obtained. (Mechanism of this step: First, calcination in air ensures stable V₂O₅ formation, while simultaneously solidifying the phosphating-coated precursor into amorphous vanadium phosphorus oxide V₂O₅.) x P y O z (i.e., phosphating coating); secondly, calcination under an inert atmosphere can achieve thermal reduction of graphene oxide to generate reduced graphene oxide (rGO), and the BOV / C covalent bond structure is stable during the reduction process, combining with V2O5 particles to construct a continuous conductive network).

[0012] According to one embodiment of the present invention, during the preparation of the graphene oxide reverse micelle dispersion, ultrasonic dispersion is performed for 10 to 30 minutes.

[0013] According to one embodiment of the present invention, the surfactant is at least one selected from hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and sodium tetradecyl sulfate; the co-surfactant is at least one selected from n-butanol, n-pentanol, and tetraethylene glycol; the organic solvent is at least one selected from cyclohexane and n-heptane; and the hydroxyl-containing borate coupling agent is at least one selected from 3-hydroxyphenylboronic acid, 4-hydroxyphenylboronic acid, 2-(3,4-dihydroxyphenyl)ethylboronic acid, and polyvinyl alcohol-grafted-borate. The hydroxyl-containing borate coupling agent refers to a compound whose molecular structure simultaneously contains at least one hydroxyl group and at least one borate group. One end of the borate group undergoes a dehydration condensation reaction with the hydroxyl groups on the graphene surface, while the other end of the borate group coordinates with oxygen ions on the V₂O₅ crystal nucleus surface to form a BOV / C covalent bond, providing chemical bond anchoring sites for the uniform and robust loading of V₂O₅.

[0014] According to one embodiment of the present invention, the mass ratio of the surfactant, co-surfactant, organic solvent, and deionized water is 1:(0.5~2):(5~20):(0.5~1); the mass ratio of the coupling agent to graphene oxide is 1:(10~30); and the mass ratio of graphene oxide to the mixture is 1:(50~300). According to another embodiment of the present invention, the vanadium source solution is an aqueous solution of a vanadium source, wherein the concentration of the vanadium source solution is 0.1~0.5 mol / L; and the molar ratio of the vanadium source to graphene oxide is (5~20):1.

[0015] According to one embodiment of the present invention, the vanadium source is at least one selected from ammonium metavanadate, sodium vanadate, vanadium oxysulfate, and ammonium polyvanadate.

[0016] According to one embodiment of the present invention, the graphene oxide reverse micelle dispersion and the vanadium source solution are stirred and reacted at 30~90°C for 4~24 hours to obtain the reaction product.

[0017] According to one embodiment of the present invention, the phosphorus source is at least one of ammonium dihydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate, the concentration of the phosphorus source solution is 0.1~0.5 mol / L, and the molar ratio of P to vanadium in the phosphorus source is (0.01~0.1):1.

[0018] According to another aspect of the present invention, a phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material is provided, which is prepared using the method described in any of the above embodiments; the material has the following characteristics:

[0019] ① Pore structure: It has a mesoporous structure of 2~50nm, with uniform pore size distribution and a specific surface area of ​​50~200m² / g, providing sufficient channels for ion transport;

[0020] ② Conductivity and interface characteristics: V2O5 particles are anchored to graphene through BOV / C covalent bonds, resulting in uniform loading and stable interfacial bonding, which can prevent particle delamination during cycling; reduced graphene oxide constructs a continuous two-dimensional conductive network, significantly improving the electronic conductivity of the material.

[0021] ③ Microscopic morphology characteristics: V2O5 nanoparticles are uniformly loaded on the graphene surface, with a loose and porous overall structure and no obvious agglomeration.

[0022] According to another aspect of the present invention, the application of any of the phosphorylated mesoporous V2O5 particle / graphene composite electrode materials as described above in lithium-ion batteries is provided.

[0023] By adopting the above technical solution, the present invention has at least one of the following advantages compared with the prior art:

[0024] (1) Synergistic effect of mesoporous structure and conductive network: V2O5 with uniform mesoporous structure (2~50nm) was prepared by utilizing the spatial confinement effect of reverse micelles and loaded onto the graphene surface. The mesoporous structure significantly increases the specific surface area of ​​the material, provides more ion transport channels, reduces ion diffusion resistance, and balances the exposure of active sites with structural stability; at the same time, the graphene constructs a continuous conductive network, which effectively improves the problem of low electronic conductivity of vanadium pentoxide.

[0025] (2) Interfacial reinforcement of BOV / C covalent bonds: BOV / C covalent bonds were formed between V2O5 and graphene through a hydroxyl-containing borate ester coupling agent. This chemical bonding method enhances the interfacial bonding force between V2O5 particles and graphene, completely solving the problems of uneven particle loading, interfacial exfoliation, and loss of active sites caused by traditional physical adsorption / van der Waals forces, and significantly improving the structural stability of the composite material;

[0026] (3) Protective effect of the amorphous phosphating coating: A continuous, dense, and defect-free amorphous phosphating layer (V2O5) is coated on the surface of V2O5. x P y O z This coating layer can effectively prevent direct contact between the electrolyte and V2O5, and suppress interfacial side reactions such as vanadium ion dissolution; at the same time, its amorphous structure can buffer the volume change of V2O5 during charging and discharging, avoid coating layer rupture, and help stabilize the electrode / electrolyte interface for a long time.

[0027] (4) Combination of reverse micelle method with two-step calcination process: This invention utilizes the spatial confinement characteristics of reverse micelle method to simultaneously complete four major functions in one reaction system: "controllable growth of V2O5 nuclei, construction of mesoporous structure, deposition of amorphous phosphating coating layer, and anchoring of BOV / C covalent bond interface". This completely eliminates the fragmented process of "first synthesizing V2O5 and then modifying it step by step", avoiding problems such as particle agglomeration and uneven coating that may be caused by multi-step processes, and greatly improving preparation efficiency and reducing production costs. At the same time, combined with a two-step calcination process, first an air atmosphere is used to ensure the stable generation of V2O5 and the solidification of the phosphating coating layer, and then an inert atmosphere is used to achieve the reduction of graphene oxide, which takes into account both the retention of V2O5 activity and the improvement of graphene conductivity. The process has strong adaptability and high controllability.

[0028] (5) The reverse micelle method used in this invention has mild preparation conditions, relatively simple operation, no need for special high temperature and high pressure equipment, low raw material cost, and is easy to realize large-scale industrial production.

[0029] (6) The preparation idea of ​​the present invention can be extended to the preparation of other metal oxide-carbon-based composite materials, breaking through the limitation of single material system, and has good technical versatility and industrial application prospects. Attached Figure Description

[0030] 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 from these drawings without creative effort.

[0031] Figure 1 This is a flowchart of the preparation method of the phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material according to the present invention;

[0032] Figure 2 This is a scanning electron microscope (SEM) image of the morphology of Example 1 in this embodiment of the invention;

[0033] Figure 3 This is a transmission electron microscope (TEM) image of Example 1 in this embodiment of the invention;

[0034] Figure 4 This is the X-ray diffraction (XRD) pattern of Example 1 in this embodiment of the invention;

[0035] Figure 5 This is a comparison chart of the rate performance of Example 1, the blank example, and the comparative example in this invention.

[0036] Figure 6 The following are capacity decay diagrams of Examples 1-3, the blank example, and the comparative example at a 1C rate in the embodiments of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0038] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0039] According to one aspect of the present invention, such as Figure 1 As shown, the embodiment of the preparation method of phosphating-coated mesoporous V2O5 particle / graphene composite electrode material generally includes the following steps:

[0040] S100, prepare a graphene oxide reverse micelle dispersion: mix surfactant, co-surfactant, organic solvent and deionized water in a mass ratio of 1:(0.5~2):(5~20):(0.5~1) and stir to form a uniform mixture; then add graphene oxide and a hydroxyl-containing borate ester coupling agent to the mixture, with the mass ratio of graphene oxide to the mixture being 1:(50~300) and the mass ratio of the coupling agent to graphene oxide being 1:(10~30); ultrasonically disperse to form a uniform graphene oxide reverse micelle dispersion;

[0041] S200, preparation of composite precursor by reaction: Under stirring conditions, add 0.1~0.5mol / L vanadium source solution to the reverse micelle dispersion of graphene oxide, the molar ratio of vanadium source to graphene oxide is (5~20):1, adjust the pH of the system to 2.5~3.0, raise the temperature to 30~90℃, and stir the reaction for 4~24 hours; add phosphorus source solution, and continue stirring the reaction for 4~8 hours;

[0042] S300, washing, drying, and calcination: The composite precursor is washed clean with organic solvent and deionized water alternately, and then vacuum dried. It is then calcined in a tube furnace at a heating rate of 5℃ / min to 400~600℃ for 2~4 hours in air atmosphere. The atmosphere in the tube furnace is then switched to an inert atmosphere (nitrogen or argon) and calcined for another 2~4 hours. After natural cooling, the phosphating-coated mesoporous V2O5 particle / graphene composite electrode material is obtained.

[0043] In step S100, a graphene oxide composite reverse micelle dispersion is prepared: graphene oxide is added to a mixture composed of a surfactant, a co-surfactant, an organic solvent, and deionized water, and ultrasonically dispersed to obtain a uniform graphene oxide composite reverse micelle dispersion. A hydroxyl-containing borate ester coupling agent is added to construct covalent bond sites to achieve interface strengthening: a hydroxyl-containing borate ester coupling agent is added to the composite reverse micelle dispersion and stirred until homogeneous.

[0044] In embodiments of the present invention, the surfactant is at least one selected from hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and sodium tetradecyl sulfate; the co-surfactant is at least one selected from n-butanol, n-pentanol, and tetraethylene glycol; and the organic solvent is at least one selected from cyclohexane and n-heptane. After mixing the above surfactant, surfactant, organic solvent, and deionized water, graphene oxide and a hydroxyl-containing borate ester coupling agent are added, and ultrasonic dispersion for 10-30 minutes is preferably performed to obtain a uniform graphene oxide reverse micelle dispersion.

[0045] In step S200, the composite precursor is prepared by reaction: Under stirring, a vanadium source solution is added to the above system, the pH is adjusted to 2.5–3.0, the temperature is raised to 30–90°C, and the reaction is stirred for 4–24 hours; a phosphorus source solution is added, and the reaction is continued for another 4–8 hours. During this process, vanadium ions enter the reverse micelle water core and undergo hydrolysis in an acidic microenvironment to generate V₂O₅ hydrate crystal nuclei; simultaneously, vanadium borate ester groups coordinate with oxygen ions on the surface of the V₂O₅ crystal nuclei to form BOV / C covalent bonds, firmly anchoring the V₂O₅ crystal nuclei to the graphene surface, thus achieving interface strengthening. Under the spatial confinement of the reverse micelle microreactor, the V₂O₅ crystal nuclei grow directionally, forming a mesoporous structure, thus obtaining a mesoporous composite intermediate. Subsequently, after adding the phosphorus source solution, the phosphorus source, under the confinement effect of the reverse micelle water core, undergoes a co-precipitation reaction with the vanadium species on the surface of the V₂O₅ precursor, forming a continuous and dense amorphous vanadium-phosphorus oxide gel precursor (i.e., the phosphating coating precursor). This precursor will solidify into an amorphous phosphating coating layer under subsequent calcination conditions. The vanadium source is at least one of ammonium metavanadate, sodium vanadate, vanadium oxysulfate, and ammonium polyvanadate; the concentration of the vanadium source solution is 0.1~0.5 mol / L; and the molar ratio of vanadium source to graphene oxide is (5~20):1. Alternatively, the phosphorus source is at least one of ammonium dihydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate; the concentration of the phosphorus source solution is 0.1~0.5 mol / L; and the molar ratio of P to vanadium in the phosphorus source is (0.01~0.1):1.

[0046] Step S300 aims to achieve crystallization, reduction, and structural fixation: after washing and drying the composite intermediate, a two-step calcination process is performed using a tube furnace. First, calcination is carried out in an air atmosphere to ensure the stable formation of V2O5, while simultaneously solidifying the phosphating coating precursor into amorphous vanadium phosphorus oxide (V2O5). x P y O z (i.e., phosphating coating), and then calcined under an inert atmosphere to achieve thermal reduction of graphene oxide, generating reduced graphene oxide (rGO), and the BOV / C covalent bond structure is stable during the reduction process.

[0047] According to another aspect of the present invention, the present invention also provides an electrode material prepared by the above method. This material may have the following characteristics:

[0048] ① Pore structure: It has a mesoporous structure of 2~50nm, with uniform pore size distribution and a specific surface area of ​​50~200m² / g, providing sufficient channels for ion transport;

[0049] ② Conductivity and interface characteristics: V2O5 particles are anchored to graphene through BOV / C covalent bonds, resulting in uniform loading and stable interfacial bonding, which can prevent particle delamination during cycling; reduced graphene oxide constructs a continuous two-dimensional conductive network, significantly improving the electronic conductivity of the material.

[0050] ③ Microscopic morphology characteristics: V2O5 nanoparticles are uniformly loaded on the graphene surface, with a loose and porous overall structure and no obvious agglomeration.

[0051] According to another aspect of the present invention, the present invention also provides the application of any of the phosphorylated mesoporous V2O5 particle / graphene composite electrode materials as described above in lithium-ion batteries.

[0052] Example 1

[0053] A method for preparing phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material by reverse micelle method includes the following steps:

[0054] S100, prepare a graphene oxide reverse micelle dispersion by mixing 1g cetyltrimethylammonium bromide (CATB), 0.5g n-butanol, 5g cyclohexane and 0.5g deionized water evenly (the mass ratio of surfactant, co-surfactant, organic solvent and deionized water is 1:0.5:5:0.5) to obtain a uniform mixture. Add 0.04g graphene oxide and 0.004g 3-hydroxyphenylboronic acid to the above mixture (the mass ratio of graphene oxide to the mixture is 1:175, and the mass ratio of coupling agent to graphene oxide is 1:10). Disperse evenly by ultrasonication to obtain a graphene oxide reverse micelle dispersion.

[0055] Under stirring conditions, 0.1 mol / L ammonium metavanadate solution was slowly added to the reverse micelle dispersion of graphene oxide (S200). The molar ratio of ammonium metavanadate to graphene oxide was 10:1. The pH of the system was adjusted to 2.5, the temperature was raised to 50°C, and the reaction was stirred for 12 hours. Then, 0.1 mol / L ammonium dihydrogen phosphate solution (P and V) was added. 5+ With a molar ratio of 1:20 (i.e., 0.05:1), continue stirring the reaction for 6 hours to obtain the composite precursor;

[0056] S300, washing, drying, and calcination: After the reaction is completed, the reaction product is separated by centrifugation and washed three times alternately with cyclohexane and deionized water. The washed product is then vacuum dried at 60°C for 12 hours. Subsequently, it is transferred to a tube furnace, where an air atmosphere is first introduced, and the temperature is raised to 400°C at a rate of 5°C / min. The furnace is then calcined for 4 hours, and the temperature is kept constant at 400°C. The atmosphere is then switched to nitrogen, and the furnace is calcined for another 4 hours to reduce graphene oxide to graphene. After natural cooling, the phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material is obtained.

[0057] Testing revealed that the mesopore size of this composite electrode material is 5-50 nm, and its specific surface area is 52-78 m². 2 / g. When applied to lithium-ion batteries, it exhibits an initial discharge specific capacity of 317 mAh / g at 0.1C rate and a capacity retention of 84.6% after 300 cycles at 1C rate.

[0058] Figures 2-4 The images shown are, in order, scanning electron microscope (SEM) images, transmission electron microscope (TEM) images, and X-ray diffraction (XRD) patterns of the composite electrode material obtained in this embodiment.

[0059] from Figure 2 As can be seen, the graphene is in sheet form, while the vanadium pentoxide is in particle form with a particle size of 50-200 nm, and the particles are uniformly loaded on the graphene surface. The reverse micelle method enables the formation of a mesoporous structure, increases the specific surface area, inhibits the aggregation of graphene particles, constructs a conductive network, which is beneficial to improving electrochemical performance and demonstrates the advantages of the patented process.

[0060] from Figure 3 As can be seen, the sheet-like graphene is clearly visible, with granular vanadium pentoxide uniformly attached to its surface. The particles are well dispersed and do not show obvious agglomeration.

[0061] from Figure 4 It can be seen that the diffraction peaks of the composite electrode material are sharp and have high intensity, indicating that the mesoporous vanadium pentoxide-graphene composite material has good crystallinity. The peak positions correspond to the characteristic crystal planes of V2O5, indicating that the V2O5 phase was successfully synthesized. The absence of obvious impurity peaks indicates that the product has high purity, which is beneficial to ensuring electrochemical performance.

[0062] Example 2

[0063] A method for preparing phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material by reverse micelle method includes the following steps:

[0064] S100, Prepare a reverse micelle dispersion of graphene oxide: Mix 1g sodium dodecylbenzenesulfonate, 2g n-pentanol, 20g n-heptane and 0.8g deionized water evenly (the mass ratio of surfactant, co-surfactant, organic solvent and deionized water is 1:2:20:0.8) to obtain a mixture. Add 0.10g graphene oxide and 0.01g 4-hydroxyphenylboronic acid to the above mixture (the mass ratio of graphene oxide to the mixture is 1:238, and the mass ratio of coupling agent to graphene oxide is 1:10). Disperse evenly by ultrasonication to obtain a reverse micelle dispersion of graphene oxide.

[0065] S200, under stirring conditions, slowly add 0.5 mol / L sodium vanadate solution to the reverse micelle dispersion of graphene oxide. The molar ratio of sodium vanadate to graphene oxide is 10:1. Adjust the pH of the system to 2.8, raise the temperature to 60℃ and stir for 10 hours; then add 0.2 mol / L ammonium dihydrogen phosphate solution (P and V... 5+With a molar ratio of 1:10 (i.e., 0.1:1), continue stirring the reaction for 6 hours to obtain the composite precursor;

[0066] S300, washing, drying, and calcination: After the reaction is completed, the reaction product is separated by centrifugation and washed three times alternately with cyclohexane and deionized water. The washed product is then vacuum dried at 60°C for 12 hours. Subsequently, it is transferred to a tube furnace, where an air atmosphere is first introduced, and the temperature is raised to 500°C at a rate of 5°C / min. The furnace is then calcined for 4 hours, and the temperature is kept constant at 500°C. The atmosphere is then switched to nitrogen, and the furnace is calcined for another 3 hours to reduce graphene oxide to graphene. After natural cooling, the phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material is obtained.

[0067] Testing revealed that the mesopore size of this composite electrode material is 2-30 nm, and its specific surface area is 182-200 m². 2 / g. When applied to lithium-ion batteries, it exhibits an initial discharge specific capacity of 324.1 mAh / g at 0.1C rate and a capacity retention of 86.9% after 300 cycles at 1C rate.

[0068] Example 3

[0069] A method for preparing phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material by reverse micelle method includes the following steps:

[0070] S100, Prepare a reverse micelle dispersion of graphene oxide: Mix 1g sodium dodecyl sulfate, 1g tetraethylene glycol, 10g cyclohexane and 1g deionized water evenly (the mass ratio of surfactant, co-surfactant, organic solvent and deionized water is 1:1:10:1) to obtain a mixture. Add 0.06g graphene oxide and 0.006g 3-hydroxyphenylboronic acid to the above mixture (the mass ratio of graphene oxide to the mixture is 1:217, and the mass ratio of coupling agent to graphene oxide is 1:10). Disperse evenly by ultrasonication to obtain a reverse micelle dispersion of graphene oxide.

[0071] Under stirring conditions, 0.3 mol / L vanadium oxysulfate solution was slowly added to the reverse micelle dispersion of graphene oxide (S200). The molar ratio of vanadium oxysulfate to graphene oxide was 10:1. The pH of the system was adjusted to 3.0, and the temperature was raised to 70°C and stirred for 6 hours. Then, 0.3 mol / L sodium dihydrogen phosphate solution (P and V) was added. 5+ With a molar ratio of 1:50 (i.e., 0.02:1), continue stirring the reaction for 7 hours to obtain the composite precursor;

[0072] S300, washing, drying, and calcination: After the reaction is completed, the reaction product is separated by centrifugation and washed three times alternately with cyclohexane and deionized water. The washed product is then vacuum dried at 60°C for 12 hours. Subsequently, it is transferred to a tube furnace, where an air atmosphere is first introduced, and the temperature is raised to 600°C at a rate of 5°C / min. The furnace is then calcined for 3 hours, and the temperature is kept constant at 600°C. The atmosphere is then switched to nitrogen, and the furnace is calcined for another 2 hours to reduce graphene oxide to graphene. After natural cooling, the phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material is obtained.

[0073] Testing revealed that the mesopore size of this composite electrode material is 10–50 nm, and its specific surface area is 10⁸–120 m² / g. 2 / g. When applied to lithium-ion batteries, it exhibits an initial discharge specific capacity of 309.6 mAh / g at 0.1C rate and a capacity retention of 83.6% after 300 cycles at 1C rate.

[0074] Blank example

[0075] A commercially available nano-V2O5 powder.

[0076] Comparative Example

[0077] Electrode materials were prepared using a traditional mechanical mixing method: commercial nano-V2O5 powder and graphene were mechanically ground and mixed at a V to graphene molar ratio of 10:1 (ball mill, 300 rpm, 2 h) to obtain electrode materials with the same vanadium to graphene molar ratio as in Examples 1-3.

[0078] Example 1 3. The electrode materials used in the blank example and comparative example were used to prepare coin cells and their performance was tested.

[0079] Specifically, Example 1 3. In the blank and comparative examples, the electrode material, conductive agent (super-P conductive carbon black), and binder (polyvinylidene fluoride, PVDF) were mixed at a mass ratio of 7:2:1 under normal temperature conditions in N... The active material is uniformly mixed with methylpyrrolidone (NMP) and then uniformly coated onto an aluminum current collector, with an active material surface loading of 2.0~5.0 mg / cm³. 2The cells were then dried, cut, and rolled before being transferred to a glove box for storage. CR2032 coin cells were assembled in an argon-filled glove box. The negative electrode was a lithium metal sheet, the separator was a Celgard 2400 membrane, and the electrolyte was 1.2M LiPF6 dissolved in an EC:EMC mixture at a solvent ratio of 3:7wt%. The coin cells were first activated at a current density of 0.1C (1C = 443 mA / g), followed by charge-discharge cycles at 1C, with a test voltage range of 1.5–4.0V. Rate testing was performed sequentially at 0.1C, 0.2C, 0.5C, 1C, and 2C, five cycles each, before returning to 0.1C. Since graphene cannot provide specific capacity, the specific capacity of the electrode material was calculated using V₂O₅. Specific cycle performance results are shown in Table 1.

[0080] Table 1 Cycle performance of button cells

[0081]

[0082] As can be seen from Table 1, Examples 1-3 have two significant performance advantages.

[0083] First, the initial discharge capacity at 0.1C is significantly improved compared to the blank example and the comparative examples. The initial discharge capacity of Examples 1-3 at 0.1C (306.8-311.4 mAh / g) is significantly higher than that of the blank example (258.9 mAh / g) and the comparative example (266.4 mAh / g). This is because of the structural advantages of the materials in Examples 1-3: ① Mesoporous structure enables full exposure of active sites: The 2-50 nm mesoporous structure constructed with the reverse micelle confinement effect greatly increases the specific surface area of ​​the material, exposing more V2O5 active sites, allowing for more complete vanadium ion insertion / extraction reactions, improving the utilization rate of active sites, and thus releasing higher discharge capacity. ② Significantly improved ion transport efficiency: The mesoporous structure provides sufficient diffusion channels for lithium ions, effectively alleviating ion diffusion resistance, while promoting full electrolyte wetting, accelerating the transport rate of lithium ions inside the material and at the material-electrolyte interface, reducing capacity loss, and improving capacity utilization during charge and discharge. ③ Optimized electronic conduction efficiency: The graphene generated by the two-step calcination and reduction process constructs a continuous two-dimensional conductive network. Combined with the interfacial bridging effect of BOV / C covalent bonds, this significantly improves the material's electronic conductivity, preventing the idleness of active sites due to blocked electron transport and ensuring full capacity release. The synergy of these three factors makes lithium-ion insertion / extraction more efficient, improving discharge capacity and highlighting the material's design advantages.

[0084] Secondly, after 1C and 300 cycles, Examples 1-3 showed a capacity retention of 88.9%-90.9%, compared to only 32.5% in the blank example and 60.2% in the comparative example, a significant difference. This is because: ① The interfacial bonding stability is greatly enhanced: The BOV / C covalent bonds formed by the hydroxyl-containing borate ester coupling agent chemically anchor the mesoporous V2O5 particles to graphene, completely solving the particle stripping problem caused by traditional physical adsorption / van der Waals forces during cycling and reducing the loss of active sites. ② The amorphous phosphide coating layer provides efficient protection: The continuous and dense amorphous vanadium phosphorus oxide coating layer, without grain boundary defects, can effectively block the contact between the electrolyte and the V2O5 matrix, significantly inhibit interfacial side reactions such as vanadium dissolution, and avoid battery performance deterioration caused by vanadium ion migration; it can also adapt to the volume expansion during charging and discharging, possessing good structural self-adaptation capabilities and preventing coating layer cracking and failure. ③ Enhanced structural stability: The supporting effect of graphene sheets combined with the buffering effect of mesoporous structures effectively alleviates the volume expansion stress during V2O5 charging and discharging, preventing material structure collapse. Simultaneously, it inhibits particle agglomeration, ensuring the structural integrity of the material during cycling and reducing capacity decay. This triple effect reduces structural collapse and loss of active sites during cycling, ensuring cycling stability and demonstrating the value of the preparation process.

[0085] The specific rate performance of the button cell is shown in Table 2:

[0086] Table 2. Rate performance of button cells

[0087]

[0088] Table 2 shows that Examples 1-3 exhibit superior rate performance, with the advantage becoming more pronounced at higher rates. This is because the continuous two-dimensional conductive network constructed from graphene, combined with the interfacial bridging effect of BOV / C covalent bonds, significantly enhances the material's electronic conductivity and accelerates rapid electron transport. The mesoporous structure provides ample diffusion channels for lithium ions, effectively reducing ion diffusion resistance and promoting full electrolyte wetting, achieving efficient synergistic transport of electrons and lithium ions. Simultaneously, the amorphous phosphating coating stabilizes the electrolyte interface, inhibits particle aggregation, and prevents the loss of active sites and structural damage under high-rate charge-discharge conditions, thereby significantly improving the material's rate performance and enabling it to maintain excellent capacity even at high rates.

[0089] Figure 5 This is a comparison chart of the rate performance of Example 1, the blank example, and the comparative example. From... Figure 5It can be seen that Example 1 exhibits the best rate performance: as the rate increases from 0.1C to 2C, the discharge capacity of Example 1 decreases less, while that of the blank example decreases more; when the rate drops back, the capacity recovery of Example 1 is good, while that of the blank example and the comparative example is poor. The above phenomena indicate that Example 1 achieves performance improvement by virtue of the multiple synergistic modification advantages of the present invention: the continuous two-dimensional conductive network and mesoporous structure constructed by graphene provide sufficient diffusion channels for lithium ions, synergistically achieving efficient synergistic transport of electrons and lithium ions, while the shaped phosphating coating stabilizes the electrolyte interface and avoids structural damage, thereby significantly improving the rate performance of the material; the blank example is pure V2O5, which has inherent defects such as low electronic conductivity, easy volume expansion and particle agglomeration during charging and discharging, resulting in poor rate performance; the comparative example did not accurately construct a mesoporous structure, and did not form BOV / C covalent bonds to strengthen the interface bonding, lacked amorphous phosphating coating protection, and the bond between V2O5 and graphene was weak, so its rate performance and capacity recovery ability were weaker than those of Example 1.

[0090] Figure 6 The diagram shows the capacity decay of Examples 1-3, the blank example, and the comparative example at a 1C rate. From... Figure 6 It can be seen that after 300 cycles, Examples 1-3 exhibited slow discharge capacity decay and a retention rate exceeding 88%; the blank example showed rapid decay with a retention rate of only 32.5%; the comparative example was in the middle (60.2%), demonstrating a significant performance advantage of the examples. This is because the examples, through the mesoporous structure constructed by the reverse micelle method, the BOV / C covalent bond interface anchoring, and the synergistic effect of the amorphous phosphating coating layer and graphene conductive network, effectively alleviated volume expansion, inhibited particle agglomeration and vanadium dissolution, enhanced interface stability, and improved electronic conduction efficiency, ensuring structural and electrochemical stability during cycling; the blank example, with its pure V2O5, suffered from inherent defects such as low conductivity, easy expansion and agglomeration, and severe vanadium dissolution, leading to rapid capacity decay; the comparative example lacked precise mesoporous control, covalent bond interface reinforcement, and amorphous phosphating coating protection, resulting in inferior performance compared to the examples.

[0091] The vanadium concentrations dissolved into the electrolyte after 300 cycles at 1C rate for coin cells based on the electrodes of Examples 1-3, the blank example, and the comparative example are shown in Table 3.

[0092] Table 3 Vanadium concentration in electrolyte

[0093]

[0094] As shown in Table 3, the vanadium concentrations in Examples 1-3 were only 10.8-14.5 μg / mL, far lower than the blank example (98.6 μg / mL) and the comparative example (65.2 μg / mL), demonstrating a significant vanadium dissolution inhibition effect. This is because: the embodiments of the present invention rely on the synergistic effect of the amorphous phosphating coating layer, BOV / C covalent bonds, and mesoporous structure. The continuous and dense amorphous phosphating coating layer forms a physical barrier, preventing the electrolyte from contacting the V2O5 matrix and effectively inhibiting vanadium dissolution; the BOV / C covalent bonds strengthen the interfacial bonding, reducing the exposure of vanadium species caused by structural collapse; and the mesoporous structure alleviates volume expansion, ensuring the continuity of the coating layer's protection. The blank example, lacking any modified protection, experienced severe volume expansion and structural collapse, resulting in uninhibited vanadium dissolution and the highest concentration; the comparative example, lacking a phosphating coating layer, allowed the electrolyte to directly contact V2O5, and vanadium dissolution was only slightly inhibited by graphene.

[0095] The composite electrode material prepared by the method of this invention has three major advantages: First, the mesoporous structure is precisely controlled, with uniform mesopore size (2~50nm) and high specific surface area (50~200nm). 2 The composite electrode material exhibits several advantages: First, it significantly expands the electrode / electrolyte reaction interface, shortens the lithium-ion diffusion distance, improves ion transport efficiency, and helps active sites fully function. Second, the BOV / C interface covalent bonds achieve a firm anchoring of V2O5 and graphene, and the continuous electron transport network formed by graphene enhances electron conductivity by 1-2 orders of magnitude, completely solving the problems of easy interface peeling and discontinuous conductive networks in traditional composite systems. Third, the two-dimensional confinement effect of graphene inhibits particle agglomeration and volume expansion during charge and discharge, significantly improving cycle stability. Fourth, the dense and continuous amorphous phosphating coating layer effectively blocks the contact between the electrolyte and the V2O5 matrix, inhibits vanadium dissolution, and adapts to volume expansion during charge and discharge, synergistically improving the material's structural stability. When used as a positive electrode in lithium-ion batteries, this composite electrode material achieves an initial discharge specific capacity of 310 mAh / g at 0.1C rate and a capacity retention rate of over 88% after 300 cycles at 1C, outperforming composite materials prepared by traditional methods. This material can provide power battery companies with a high-performance cathode option, helping to improve battery energy density and cycle life, and promoting cost reduction and efficiency improvement in the new energy industry. Furthermore, the reverse micelle method is simple, uses low-cost raw materials, and is suitable for large-scale production, significantly reducing preparation costs compared to traditional sol-gel, hydrothermal, and solvothermal methods. After widespread application, this technology can be extended to the preparation of other metal oxide-carbon-based composite materials, providing a new technological paradigm for the energy storage materials field and possessing broad industrialization prospects.

[0096] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

[0097] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of the present invention is limited to these examples; within the framework of the embodiments of the present invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of the present invention should be included within the protection scope of the embodiments of the present invention.

Claims

1. A method for preparing a phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material, characterized in that, Includes the following steps: Preparation of graphene oxide reverse micelle dispersion: Mix surfactant, co-surfactant, organic solvent and deionized water at a mass ratio of 1:(0.5~2):(5~20):(0.5~1) and stir to form a homogeneous mixture; then add graphene oxide and a hydroxyl-containing borate ester coupling agent to the mixture, with the mass ratio of graphene oxide to the mixture being 1:(50~300) and the mass ratio of the coupling agent to graphene oxide being 1:(10~30); disperse evenly by ultrasonication to form a homogeneous graphene oxide reverse micelle dispersion; Preparation of composite precursor by reaction: Under stirring conditions, add 0.1~0.5mol / L vanadium source solution to the reverse micelle dispersion of graphene oxide, the molar ratio of vanadium source to graphene oxide is (5~20):1, adjust the pH of the system to 2.5~3.0, raise the temperature to 30~90℃, and stir the reaction for 4~24 hours; add phosphorus source solution, and continue stirring the reaction for 4~8 hours; Washing, drying, and calcination: The composite precursor is washed clean with organic solvent and deionized water alternately, and then vacuum dried. It is then calcined in a tube furnace at a heating rate of 5℃ / min to 400~600℃ for 2~4 hours in air atmosphere. The atmosphere in the tube furnace is then switched to an inert atmosphere and calcined for another 2~4 hours. After natural cooling, the phosphating-coated mesoporous V2O5 particle / graphene composite electrode material is obtained.

2. The method for preparing the phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material according to claim 1, characterized in that, During the preparation of the graphene oxide reverse micelle dispersion, ultrasonic dispersion is performed for 10-30 minutes.

3. The method for preparing the phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material according to claim 1, characterized in that, The surfactant is at least one of hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and sodium tetradecyl sulfate. The co-surfactant is at least one of n-butanol, n-pentanol, and tetraethylene glycol; The organic solvent is at least one of cyclohexane and n-heptane; the hydroxyl-containing borate coupling agent is at least one of 3-hydroxyphenylboronic acid, 4-hydroxyphenylboronic acid, 2-(3,4-dihydroxyphenyl)ethylboronic acid, and polyvinyl alcohol-grafted-borate.

4. The method for preparing the phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material according to claim 3, characterized in that, The mass ratio of the surfactant, the co-surfactant, the organic solvent, and the deionized water is 1:(0.5~2):(5~20):(0.5~1); The mass ratio of coupling agent to graphene oxide is 1:(10~30); The mass ratio of graphene oxide to the mixture is 1:(50~300).

5. The method for preparing the phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material according to claim 1, characterized in that, The vanadium source solution is an aqueous solution of a vanadium source, wherein, The concentration of the vanadium source solution is 0.1~0.5 mol / L; The molar ratio of the vanadium source to graphene oxide is (5~20):

1.

6. The method for preparing the phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material according to claim 5, characterized in that, The vanadium source is at least one of ammonium metavanadate, sodium vanadate, vanadium oxysulfate, and ammonium polyvanadate.

7. The method for preparing the phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material according to claim 1, characterized in that, The graphene oxide reverse micelle dispersion and the vanadium source solution are stirred and reacted at 30~90℃ for 4~24 hours to obtain the reaction product.

8. The method for preparing the phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material according to claim 1, characterized in that, The phosphorus source is at least one of ammonium dihydrogen phosphate, sodium dihydrogen phosphate, and potassium dihydrogen phosphate. The concentration of the phosphorus source solution is 0.1~0.5 mol / L, and the molar ratio of P to vanadium in the phosphorus source is (0.01~0.1):

1.

9. A phosphating-coated mesoporous V₂O₅ particle / graphene composite electrode material, characterized in that, The material prepared using the method according to any one of claims 1 to 8 has the following characteristics: Pore ​​structure: It has a mesoporous structure of 2~50nm, with uniform pore size distribution and a specific surface area of ​​50~200m² / g, providing sufficient channels for ion transport; Conductivity and interface characteristics: V2O5 particles are anchored to graphene through BOV / C covalent bonds, resulting in uniform loading and stable interfacial bonding, which can prevent particle delamination during cycling; reduced graphene oxide constructs a continuous two-dimensional conductive network, significantly improving the electronic conductivity of the material. Microscopic morphology characteristics: V2O5 nanoparticles are uniformly loaded on the graphene surface, with a loose and porous overall structure and no obvious agglomeration.

10. The application of the phosphorus-coated mesoporous V2O5 particle / graphene composite electrode material according to claim 9 in lithium-ion batteries.

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