A novel sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode and its preparation method

Abstract

The present invention relates to a novel sodium-based dual-ion battery in which phosphorus is encapsulated in a mesoporous graphene negative electrode and a preparation method thereof. Due to the presence of the graphene substrate, not only the agglomeration of phosphorus particles is prevented and the absolute strain is reduced, but also the structural stability under sodiumization and desodiumization is improved. The negative electrode exhibits excellent long cycle performance, large reversible capacity and excellent rate performance. The doping of nitrogen elements and the formation of phosphorus-carbon chemical bonds in the graphene matrix can increase the adsorption energy of phosphorus atoms and provide an effective contact area. After pairing with a positive electrode containing a carbon material, an innovative sodium-based dual-ion battery is manufactured, and the electrolyte is a 0.1-5M sodium salt electrolyte. The preparation method of the present invention is green and environmentally friendly, has high batch stability, is conducive to large-scale preparation, is easy to mass-produce, and opens up an effective strategy for high-performance sodium-based dual-ion batteries for electric vehicles and other applications.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries and dual-ion batteries, and in particular to a novel fast-charging, high-energy sodium-based dual-ion battery in which phosphorus is encapsulated in a mesoporous graphene negative electrode, and a preparation method thereof. Background Art

[0002] The high demand of the electric vehicle and portable electronics markets has driven the development of low-cost, high-performance advanced energy storage technologies. In recent years, sodium-based dual-ion batteries (SDIBs) have attracted increasing attention due to their environmental friendliness, high operating voltage, and low cost. Dual-graphite batteries using graphite as cathode and anode are the most common type of dual-ion batteries (DIBs). Graphite, which has been widely studied as the negative electrode, can only store a small amount of sodium ions to form NaC 64 , resulting in a lower capacity of approximately 30 mAh g -1 Therefore, designing suitable anode materials to satisfy the efficient insertion / deintercalation of large-sized Na ions is crucial for developing high-performance SDIBs.

[0003] Among all candidate anodes, red phosphorus (RP) is the most promising due to its large theoretical capacity (2596 mA·h·g -1 , based on the reaction, 3Na+P→Na3P) is considered to be a particularly promising anode for sodium ion storage. However, RP suffers from poor conductivity (~10 -14 S cm -1 ) and large volume change (~400%) after sodiumization, resulting in sluggish electrochemical reaction kinetics and short cycle life. To address these issues, various RP particles and RP-based composites with designed nanostructures and highly conductive matrix composites (e.g., polypyrrole, carbon black, mesoporous carbon, graphene, and carbon nanotubes) have been studied. However, in RP-based anodes for sodium ion storage, achieving high reversible capacity at high current density after long-term cycling testing (>1000 cycles) remains challenging. Summary of the Invention

[0004] To address the current problems of lithium-ion batteries, such as high cost, large sodium ions that are difficult to embed into graphite negative electrode materials, and the lack of commercialization of sodium-based dual-ion batteries, the present invention provides a new fast-charging, high-energy sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode and a preparation method thereof.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A novel sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode, the sodium-based dual-ion battery comprising a carbon positive electrode material, an electrolyte, and a phosphorus encapsulated in a mesoporous graphene negative electrode material; wherein,

[0007] The phosphorus encapsulated in mesoporous graphene negative electrode material is prepared by in-situ compounding of mesoporous graphene and phosphorus, wherein the content of the mesoporous graphene is 10-70%, and the content of the phosphorus is 30-90%.

[0008] The electrolyte is a 0.1-5M sodium salt electrolyte.

[0009] Preferably, the mesoporous graphene is at least one of few-layer graphene, multi-layer graphene, and functionalized modified graphene.

[0010] Preferably, the phosphorus is black phosphorus, red phosphorus or white phosphorus.

[0011] Preferably, the carbon positive electrode material is at least one of graphene, expanded graphite, nanographite, graphite, soft carbon, hard carbon, natural graphite, artificial graphite, carbon nanotubes, expanded graphite, coated graphite, and three-dimensional graphene.

[0012] Preferably, the electrolyte of the sodium salt electrolyte is at least one of sodium hexafluorophosphate (NaPF6), sodium fluoride (NaF), sodium tetrafluoroborate (NaBF4), and sodium perchlorate (NaClO4);

[0013] The solvent of the sodium salt electrolyte is at least one of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), methylpropyl carbonate (MPC), ethyl methyl carbonate (EMC), fluoroethylene carbonate (FEC), 1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), methyl ester (PA), butylene carbonate (BC), and methyl acetate (MA).

[0014] The present invention also claims protection for a method for preparing the novel sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode, which specifically comprises the following steps:

[0015] 1) Preparation of a phosphorus-encapsulated mesoporous graphene anode material: in-situ vapor-phase compounding of mesoporous graphene and phosphorus in a certain proportion, maintaining a constant temperature of 500-900°C for 2-12 hours, allowing phosphorus to diffuse into the mesoporous graphene with a multi-level pore structure through vapor phase diffusion, then cooling to 100-300°C and maintaining the constant temperature for 12-48 hours, and finally naturally cooling to room temperature;

[0016] 2) Pairing the negative electrode material prepared in step 1) with the carbon positive electrode material, and assembling them in a glove box with an argon atmosphere to obtain the sodium-based dual-ion battery.

[0017] It can be seen from the above technical solution that, compared with the prior art, the novel sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode and the preparation method thereof provided by the present invention have the following excellent effects:

[0018] (1) The negative electrode material of the present invention adopts an in-situ composite of mesoporous graphene and phosphorus material. Compared with the interlayer spacing of graphite, phosphorus has a larger interlayer spacing (0.53nm), which is conducive to promoting the embedding of sodium ions during the charging process, effectively increasing the sodium ion loading capacity in the negative electrode material, thereby significantly increasing the specific capacity of the negative electrode material.

[0019] (2) The negative electrode material of the present invention is based on encapsulating phosphorus into a mesoporous graphene matrix. Due to the presence of the graphene matrix, it is beneficial to prevent the agglomeration of phosphorus particles and reduce the absolute strain, thereby improving the structural stability under sodiumization and desodiumization.

[0020] (3) The sodium-based dual-ion battery provided by the present invention, which uses phosphorus encapsulated in mesoporous graphene as the negative electrode material, has the following characteristics: the negative electrode material can achieve high reversible capacity in the high voltage range of 2.5-4.2V during charge and discharge, and shows 89mA·h·g at 1C and 5C respectively. -1 and 66mA·h·g -1 The large reversible capacity and excellent long-cycle stability are maintained. The capacity retention rate is as high as 92% after 1000 cycles, which fully demonstrates that the specific capacity of the sodium-based dual-ion battery using phosphorus encapsulated in mesoporous graphene as the negative electrode material is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0022] Figure 1 Schematic diagram of the working principle of sodium-based dual-ion battery.

[0023] Figure 2 This is a TEM image of phosphorus encapsulated in the mesoporous graphene negative electrode of Example 1 of the present invention.

[0024] Figure 3 This is a charge and discharge cycle curve diagram of the sodium-based dual-ion battery of Example 1 of the present invention at a 1C rate.

[0025] Figure 4 This is a charge and discharge cycle performance diagram of the sodium-based dual-ion battery of Example 2 of the present invention at a 1C rate.

[0026] Figure 5 This is a charge and discharge cycle performance diagram of the sodium-based dual-ion battery of Example 3 of the present invention at a 5C rate. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] The embodiment of the present invention discloses a novel sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode.

[0029] For a better understanding of the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as limiting the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content are also considered to fall within the scope of protection of the present invention.

[0030] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0031] Example 1

[0032] The sodium-based dual-ion battery of this embodiment uses phosphorus encapsulated in a mesoporous graphene material as the negative electrode material, wherein red phosphorus accounts for 40% of the total mass of the negative electrode material and mesoporous graphene accounts for 60% of the total mass of the negative electrode material; the preparation steps of the phosphorus encapsulated in the mesoporous graphene negative electrode material are as follows: 60% mesoporous graphene and 40% phosphorus are in situ gas-phase compounded in proportion, kept at a constant temperature of 900°C for 8 hours, and phosphorus enters the mesoporous graphene with a multi-level pore structure through gas-phase diffusion, then the temperature is reduced to 300°C and kept at a constant temperature for 24 hours, and finally naturally cooled to room temperature.

[0033] Expanded graphite was used as the positive electrode material; 1M sodium hexafluorophosphate (NaPF6) was dissolved in a mixed solution of diethyl carbonate (DEC): dimethyl carbonate (DMC) with a volume ratio of 7:3 (v1:v2=7:3) as the electrolyte, and sodium-based dual-ion batteries were assembled and their performance tested.

[0034] in, Figure 1 The diagram shows the working principle of sodium-based dual-ion battery. During the charge and discharge process, expanded graphite is used as the positive electrode material, PF6 - Anions can be reversibly embedded / extracted in its sheet structure; phosphorus is encapsulated in mesoporous graphene as the negative electrode material, Na + It can be reversibly inserted / extracted from its mesoporous structure. Figure 2 It shows that the phosphorus nanoparticles prepared by this method can be uniformly encapsulated in the mesoporous structure of graphene.

[0035] like Figure 3As shown in the figure, the electrochemical performance of the sodium-based dual-ion battery of this embodiment is studied by using the charge and discharge curve. It can be seen from the figure that the sodium-based dual-ion battery is -1 ) current density, the initial charge capacity and discharge capacity reached 126 and 89 mA·h·g, respectively. -1 , the coulombic efficiency reached 70.63% for the first time, which fully demonstrated that the specific capacity of the sodium-based dual-ion battery using phosphorus encapsulated in mesoporous graphene material as the negative electrode material has been greatly improved.

[0036] Example 2

[0037] The sodium-based dual-ion battery of this embodiment uses phosphorus encapsulated in a mesoporous graphene material as the negative electrode material, wherein red phosphorus accounts for 30% of the total mass of the negative electrode material and mesoporous graphene accounts for 70% of the total mass of the negative electrode material; the preparation steps of the phosphorus encapsulated in the mesoporous graphene negative electrode material are as follows: 70% mesoporous graphene and 30% phosphorus are in situ gas-phase composited in proportion, kept at a constant temperature of 800°C for 12 hours, and phosphorus is diffused into the mesoporous graphene with a multi-level pore structure by gas phase diffusion, and then cooled to 300°C and kept at a constant temperature for 24 hours, and finally naturally cooled to room temperature.

[0038] Expanded graphite was used as the positive electrode material; 1M sodium hexafluorophosphate (NaPF6) was dissolved in a mixed solution of diethyl carbonate (DEC): dimethyl carbonate (DMC) with a volume ratio of 7:3 (v1:v2=7:3) as the electrolyte, and sodium-based dual-ion batteries were assembled and their performance tested.

[0039] like Figure 4 As shown in the figure, the electrochemical performance of the sodium-based dual-ion battery of this embodiment is studied by using the charge and discharge curve. It can be seen from the figure that the sodium-based dual-ion battery is -1 ) current density, and provided a large reversible capacity (82 mA·h·g -1 ) and high capacity retention rate (92%), which fully demonstrates that the performance stability of sodium-based dual-ion batteries using phosphorus encapsulated in mesoporous graphene materials as negative electrode materials has been greatly improved.

[0040] Example 3

[0041] The sodium-based dual-ion battery of this embodiment uses phosphorus encapsulated in a mesoporous graphene material as the negative electrode material, wherein red phosphorus accounts for 35% of the total mass of the negative electrode material and mesoporous graphene accounts for 65% of the total mass of the negative electrode material; the preparation step of the phosphorus encapsulated in the mesoporous graphene negative electrode material is to in-situ gas phase composite 65% mesoporous graphene and 35% phosphorus in proportion, maintain a constant temperature at 800°C for 18 hours, and diffuse phosphorus into the mesoporous graphene with a multi-level pore structure by gas phase diffusion, then cool to 260°C and maintain a constant temperature for 12 hours, and finally cool naturally to room temperature.

[0042] Expanded graphite was used as the positive electrode material; 1M sodium hexafluorophosphate (NaPF6) was dissolved in a mixed solution of diethyl carbonate (DEC): dimethyl carbonate (DMC) with a volume ratio of 7:3 (v1:v2=7:3) as the electrolyte; and sodium-based dual-ion batteries were assembled and their performance tested.

[0043] like Figure 5 As shown in the figure, the electrochemical performance of the sodium-based dual-ion battery of this embodiment is studied by using the charge and discharge curve. It can be seen from the figure that the sodium-based dual-ion battery is 5C (1C corresponds to 100mA·g -1 ) current density, and provided a large reversible capacity (63 mA·h·g -1 ) and an extremely low single-cycle capacity decay rate (0.0078%), which fully demonstrates that the high-rate performance of sodium-based dual-ion batteries using phosphorus encapsulated in mesoporous graphene materials as negative electrode materials has been significantly improved.

[0044] Example 4

[0045] The sodium-based dual-ion battery of this embodiment uses phosphorus encapsulated in a multilayer graphene material as the negative electrode material, wherein black phosphorus accounts for 35% of the total mass of the negative electrode material and multilayer graphene accounts for 65% of the total mass of the negative electrode material; the preparation step of the phosphorus encapsulated in the multilayer graphene negative electrode material is to in-situ vapor-phase composite 65% of the multilayer graphene and 35% of phosphorus in proportion, maintain a constant temperature at 800°C for 18 hours, and diffuse phosphorus into the multilayer graphene with a multi-level pore structure by means of phosphorus vapor phase diffusion, then cool to 260°C and maintain a constant temperature for 12 hours, and finally cool naturally to room temperature.

[0046] Nanographite was used as the positive electrode material; 1M sodium tetrafluorophosphate (NaPF4) was dissolved in a mixed solution of dimethyl carbonate (DMC): ethyl methyl carbonate (EMC) with a volume ratio of 7:3 (v1:v2=7:3) as the electrolyte; and a sodium-based dual-ion battery was assembled.

[0047] Example 5

[0048] The sodium-based dual-ion battery of this embodiment uses phosphorus encapsulated in a few-layer graphene material as the negative electrode material, wherein white phosphorus accounts for 35% of the total mass of the negative electrode material and the few-layer graphene accounts for 65% of the total mass of the negative electrode material; the preparation steps of the phosphorus encapsulated in the few-layer graphene negative electrode material are as follows: 65% few-layer graphene and 35% phosphorus are in situ gas-phase compounded in proportion, kept at a constant temperature of 800°C for 18 hours, and phosphorus is diffused into the few-layer graphene with a multi-level pore structure by gas phase diffusion, and then cooled to 260°C and kept at a constant temperature for 12 hours, and finally naturally cooled to room temperature.

[0049] Carbon nanotubes were used as the positive electrode material; 1M sodium perchlorate (NaClO4) was dissolved in a mixed solution of ethylene carbonate (EC): 1,2-dimethoxyethane (DME) with a volume ratio of 7:3 (v1:v2=7:3) as the electrolyte; and a sodium-based dual-ion battery was assembled.

[0050] Example 6

[0051] The sodium-based dual-ion battery of this embodiment uses phosphorus encapsulated in a functionally modified graphene material as the negative electrode material, wherein red phosphorus accounts for 35% of the total mass of the negative electrode material and the functionally modified graphene accounts for 65% of the total mass of the negative electrode material; the preparation step of the phosphorus encapsulated in the functionally modified graphene negative electrode material is to in-situ gas phase composite 65% of the functionally modified graphene and 35% of phosphorus in proportion, maintain a constant temperature at 800°C for 18 hours, and diffuse phosphorus into the functionally modified graphene with a multi-level pore structure by means of phosphorus gas phase diffusion, then cool to 260°C and maintain a constant temperature for 12 hours, and finally cool naturally to room temperature.

[0052] Three-dimensional graphene was used as the positive electrode material; 1M sodium fluoride (NaF) was dissolved in a mixed solution of propylene carbonate (PC) and 1,3-dioxolane (DOL) with a volume ratio of 7:3 (v1:v2=7:3) as the electrolyte; and a sodium-based dual-ion battery was assembled.

[0053] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode, characterized in that: The sodium-based dual-ion battery comprises a carbon positive electrode material, an electrolyte, and a negative electrode material in which phosphorus is encapsulated in mesoporous graphene; wherein, The phosphorus-encapsulated negative electrode material in mesoporous graphene is prepared by in-situ compounding of mesoporous graphene and phosphorus, wherein the mass content of the mesoporous graphene is 10-70%, and the mass content of the phosphorus is 30-90%. The electrolyte is a 0.1-5M sodium salt electrolyte; The preparation method of the sodium-based dual-ion battery with phosphorus encapsulated in the mesoporous graphene negative electrode specifically comprises the following steps: 1) Preparation of a phosphorus-encapsulated mesoporous graphene anode material: in-situ vapor-phase compounding of mesoporous graphene and phosphorus in a certain proportion, maintaining a constant temperature of 500-900°C for 2-12 hours, allowing phosphorus to diffuse into the mesoporous graphene with a multi-level pore structure through vapor phase diffusion, then cooling to 100-300°C and maintaining the constant temperature for 12-48 hours, and finally naturally cooling to room temperature; The phosphorus nanoparticles are uniformly encapsulated in the mesoporous structure of graphene; 2) pairing the negative electrode material prepared in step 1) with the carbon positive electrode material, and assembling them in a glove box with an argon atmosphere to obtain the sodium-based dual-ion battery; The mesoporous graphene is at least one of few-layer graphene, multi-layer graphene, and functionalized modified graphene; The phosphorus is black phosphorus, red phosphorus or white phosphorus.

2. The sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode according to claim 1, characterized in that: The carbon positive electrode material is at least one of graphene, expanded graphite, nanographite, soft carbon, hard carbon, natural graphite, artificial graphite, carbon nanotubes, and coated graphite.

3. The sodium-based dual-ion battery with phosphorus encapsulated in a mesoporous graphene negative electrode according to claim 1, characterized in that: The electrolyte of the sodium salt electrolyte is at least one of sodium hexafluorophosphate, sodium fluoride, sodium tetrafluoroborate, and sodium perchlorate; Moreover, the solvent of the sodium salt electrolyte is at least one of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methylpropyl carbonate, methylethyl carbonate, fluoroethylene carbonate, 1,3-dioxolane, 1,2-dimethoxyethane, methyl ester, butylene carbonate, and methyl acetate.

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