Halide-doped carbon skeleton, preparation method thereof and application of halide-doped carbon skeleton in negative-electrode-free lithium metal battery

Abstract

The invention discloses a halide-doped carbon skeleton, a preparation method thereof and application of the halide-doped carbon skeleton in a negative-electrode-free lithium metal battery, and belongs to the technical field of secondary batteries. The preparation method of the halide-doped carbon skeleton comprises the following steps: placing a carbon skeleton in a halide solution, and standing to obtain the halide-doped carbon skeleton. According to the halide-doped carbon skeleton prepared by the invention, the growth of lithium dendrites can be effectively inhibited by utilizing the synergistic effect of the halide and the carbon skeleton, the problem of dead lithium is solved, the cycling stability and safety of the battery are improved, and a new solution is provided for the design of a high-performance current collector of a negative-electrode-free lithium metal battery.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, and in particular to a halide-doped carbon framework, its preparation method, and its application in electrodeless lithium metal batteries. Background Technology

[0002] The booming development of portable electronics, electric vehicles, and smart grid storage has increased the demand for renewable energy storage systems, prompting researchers to propose rechargeable batteries with energy densities exceeding those of current lithium-ion batteries. Among these, lithium metal batteries have attracted significant attention and are currently a hot topic and focus of high-energy-density battery system research. Lithium metal possesses a theoretical specific capacity as high as 3860 mAh / g and a potential as low as -3.04 V, making it an ideal anode material for high-energy-density batteries. However, due to lithium's high reactivity, using excessive lithium increases safety risks and reduces the energy density of lithium metal batteries. This contradiction has led to the development of a cathode-free lithium metal battery configuration: using a copper current collector as the anode, with active lithium sources derived entirely from the cathode material. Because it does not directly use elemental lithium metal, a cathode-free lithium metal battery combines high energy density and high safety. However, due to uncontrolled lithium metal deposition on the current collector and the lack of active lithium replenishment during cycling, the active lithium source is rapidly lost and converted into dead lithium, resulting in poor battery cycle life and hindering its practical application.

[0003] In the current field of battery materials research, many researchers focus on optimizing the design of the carbon framework, especially emphasizing its key characteristic of lithium affinity, hoping to achieve uniform lithium distribution during the deposition process and thus improve battery performance. However, even after much effort and in-depth research, the results achieved in this research direction still have certain limitations, namely, they cannot fundamentally and effectively solve the so-called "dead lithium" problem. Summary of the Invention

[0004] The purpose of this invention is to provide a halide-doped carbon framework, its preparation method, and its application in a cathodeless lithium metal battery, so as to solve the problems existing in the prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention: a method for preparing a halide-doped carbon framework, comprising the following steps:

[0007] The carbon framework is placed in a solution of halides and allowed to stand to obtain the halide-doped carbon framework.

[0008] The concentration of the halide solution is 5~10 mM.

[0009] Furthermore, the carbon skeleton is selected from one of graphite paper, graphene, carbon nanotubes, carbon fiber felt, carbon fiber paper, carbon cloth, hard carbon, soft carbon, and porous carbon.

[0010] Carbon skeletons are carbon-based materials that can effectively load halides and adsorb lithium ions or promote lithium deposition.

[0011] Furthermore, the halides include fluorides, chlorides, bromides, iodides, or interhalogen compounds.

[0012] Furthermore, the fluoride includes tin fluoride, strontium fluoride, or tetrafluoroethylene (CF2CF2).

[0013] The chlorides include chloromethane (CH3Cl), vinyl chloride (CH2CHCl), or chlorobenzene (C6H5Cl);

[0014] The bromides include tin bromide, strontium bromide, bromoethane (C2H5Br), or bromobenzene (C6H5Br);

[0015] The iodides include strontium iodide or tin iodide;

[0016] The interhalogen compounds (compounds formed by different halogens sharing electron pairs) include iodine fluoride, bromine monofluoride, chlorine monofluoride, iodine chloride, bromine chloride, iodine bromide, iodine trifluoride, bromine trifluoride, chlorine trifluoride, iodine pentafluoride, bromine pentafluoride, chlorine pentafluoride, or iodine heptafluoride.

[0017] Among them, chloromethane, bromoethane, vinyl chloride, tetrafluoroethylene, chlorobenzene, and bromobenzene are organohalides.

[0018] Halides can "activate" dead lithium through redox reactions and optimize SEI formation, thereby improving battery performance and significantly extending battery cycle life.

[0019] Furthermore, the settling time is 6h to 12h.

[0020] Halides can undergo redox reactions with dead lithium to "activate" it and optimize SEI formation, thereby improving battery performance and significantly extending battery cycle life. However, halides have low solubility in electrolytes and are continuously consumed as SEI forms, making it difficult for the initially dissolved halide molecules in the electrolyte to sustain the entire battery cycle reaction.

[0021] This invention uses a carbon skeleton as a carrier, giving full play to its excellent large specific surface area, and uses halides as additives to adsorb and load them in the structural pores of the carbon skeleton, overcoming the limitation of halide solubility. Furthermore, as the battery cycle reaction proceeds, the stationary halides are gradually released into the electrolyte, which can serve as a long-lasting slow-release halide composite carbon skeleton to optimize the performance of electrodeless lithium metal batteries.

[0022] Carbon frameworks can regulate lithium deposition behavior in batteries due to their structural advantages: the porous structure of carbon frameworks can provide uniform nucleation sites for lithium metal deposition, inhibit lithium dendrite growth, and reduce the risk of short circuits caused by uneven lithium deposition; porous carbon frameworks have a large specific surface area (e.g., graphene can reach 2630 m²). 2 The carbon framework ( / g) can promote rapid lithium-ion diffusion and reduce local current density. Simultaneously, the carbon framework can further enhance electrochemical performance: highly conductive carbon materials (such as graphene and carbon nanotubes) can reduce the current collector's internal resistance (graphene's conductivity is approximately 10). 6 S / m), improving battery rate performance; the carbon skeleton surface can form a stable solid electrolyte interface (SEI), reducing electrolyte decomposition and side reactions, and improving coulombic efficiency (99.4% after using carbon skeleton in application example 2, while 98.3% when only copper foil is used as negative electrode current collector).

[0023] Halides doped in the carbon framework can improve the cycle life of batteries: after the halides are released in the electrolyte, the halogens undergo redox reactions with inactive lithium (dead lithium), converting dead lithium into reversible active lithium, which then participates in the electrochemical reaction again; at the same time, halogens can also participate in the formation of a stable SEI, generating an interface layer with high ionic conductivity and low impedance, which inhibits the continuous decomposition of the electrolyte; certain metal elements (such as tin) can both participate in the formation of a high fluoride-containing SEI to induce uniform lithium deposition, and participate in lithium alloying to promote uniform lithium metal deposition.

[0024] The second technical solution of the present invention: a halide-doped carbon framework prepared by the above preparation method.

[0025] The third technical solution of the present invention: the application of the above-mentioned halide-doped carbon framework in the preparation of negative electrode-free lithium metal batteries or lithium copper half-cells.

[0026] The fourth technical solution of the present invention: a halide-doped carbon skeleton current collector for a negative electrode-free lithium metal battery (i.e., the negative electrode of a negative electrode-free lithium metal battery), comprising the above-mentioned halide-doped carbon skeleton and copper foil rolled together.

[0027] The halide-doped carbon skeleton current collector for the electrodeless lithium metal battery of the present invention uses a carbon skeleton as a slow-release skeleton and halides as additives. The halides are fixed on the carbon skeleton and together with copper foil form the negative electrode of the electrodeless lithium metal battery.

[0028] Fifth technical solution of the present invention: A method for preparing a negative electrode-free lithium metal battery, selected from any one of the following methods:

[0029] Method 1, the steps include: using the halide-doped carbon framework current collector of the above-mentioned electrodeless lithium metal battery as the negative electrode material, using lithium-containing material as the positive electrode material, adding electrolyte for assembly, to obtain the electrodeless lithium metal battery.

[0030] Method 2 includes the following steps: adding a halide to an electrolyte and dissolving it evenly to obtain an electrolyte containing a halide; dropping the electrolyte containing a halide onto one side of a current collector composed of a carbon skeleton and copper foil that are rolled together (the carbon skeleton will adsorb the halide onto the carbon skeleton); using a lithium-containing material as the positive electrode material and dropping the electrolyte onto the positive electrode material side; assembling the battery to obtain the negative electrode-free lithium metal battery.

[0031] Further, in method 2, the electrolyte is a mixed solvent containing 1M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1 vol.% LiNO3 in ethylene glycol dimethyl ether (DME), and 1,3-dioxolane (DOL) (the volume ratio of DME to DOL is 1:1).

[0032] The carbon skeleton's ability to adsorb and support halides is mainly due to the following properties:

[0033] High specific surface area: Porous carbon materials such as carbon nanotubes and graphene, or those with high specific surface areas, have a large number of active sites on their surfaces, exhibiting strong physical adsorption capabilities (van der Waals forces). Halides (especially some large molecular weight organic halides or ions) can be physically adsorbed onto the carbon framework surface.

[0034] Oxygen-containing functional groups: The surface of the carbon skeleton often contains oxygen-containing functional groups such as carboxyl, hydroxyl, carbonyl, and lactone groups. These groups can adsorb halide ions (such as Cl-) through chemisorption or ion exchange / electrostatic interactions. - ,Br - , I - (or contains halogen molecules.)

[0035] Defect sites: Defects and edge sites on the carbon skeleton usually have higher chemical reactivity and may provide stronger chemisorption sites.

[0036] π-π interactions: For organic halides with aromatic ring structures, the sp² carbon network of the carbon skeleton (especially highly graphitized ones such as graphene and carbon nanotubes) can adsorb these molecules through π-π stacking interactions.

[0037] Furthermore, the lithium-containing material includes lithium iron phosphate, lithium cobalt oxide, ternary lithium, or lithium manganese oxide.

[0038] Furthermore, the carbon skeleton is selected from one of graphite paper, graphene, carbon nanotubes, carbon fiber felt, carbon fiber paper, carbon cloth, hard carbon, soft carbon, and porous carbon.

[0039] Furthermore, the halides include fluorides, chlorides, bromides, iodides, or interhalogen compounds.

[0040] Furthermore, the fluoride includes tin fluoride, strontium fluoride, or tetrafluoroethylene (CF2CF2).

[0041] The chlorides include chloromethane (CH3Cl), vinyl chloride (CH2CHCl), or chlorobenzene (C6H5Cl);

[0042] The bromides include tin bromide, strontium bromide, bromoethane (C2H5Br), or bromobenzene (C6H5Br);

[0043] The iodides include strontium iodide or tin iodide;

[0044] The interhalogen compounds (compounds formed by different halogens sharing electron pairs) include iodine fluoride, bromine monofluoride, chlorine monofluoride, iodine chloride, bromine chloride, iodine bromide, iodine trifluoride, bromine trifluoride, chlorine trifluoride, iodine pentafluoride, bromine pentafluoride, chlorine pentafluoride, or iodine heptafluoride.

[0045] The sixth technical solution of the present invention: a negative electrode-free lithium metal battery prepared by the above preparation method.

[0046] The present invention discloses the following technical effects:

[0047] (1) The halide-doped carbon skeleton prepared by the present invention can effectively suppress the growth of lithium dendrites by utilizing the synergistic effect of halide and carbon skeleton, solve the "dead lithium" problem, improve the cycle stability and safety of the battery, and provide a new solution for the design of high-performance current collectors for negative electrode-free lithium metal batteries.

[0048] (2) When the halide-doped carbon skeleton prepared in this invention is used as a modification layer for the negative electrode copper foil of a negative electrode-less lithium metal battery, as the battery cycle reaction proceeds, the halides on the carbon skeleton are gradually released into the electrolyte. The halides will undergo redox reactions with dead lithium to "activate" the dead lithium, which significantly extends the battery cycle life.

[0049] (3) The preparation process of the halide-doped carbon skeleton of the present invention is simple. The carbon skeleton used has good compatibility with the electrolyte, which can provide more lithium deposition sites, reduce local current density and nucleation overpotential, and induce uniform lithium nucleation. It can achieve dense deposition, reduce lithium dendrite fracture, and significantly improve the cycle coulombic efficiency (CE). Attached Figure Description

[0050] 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. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0051] Figure 1 This is a schematic diagram of the negative electrode current collector, where 1 is a halide, 2 is a carbon skeleton, and 3 is a copper foil;

[0052] Figure 2 A physical image of the carbon fiber felt used in Application Example 1;

[0053] Figure 3 The image shows the physical diagram of the negative electrode current collector composed of a tin bromide-doped carbon framework and copper foil in Application Example 1.

[0054] Figure 4 Performance comparison of the electrodeless lithium metal battery prepared in Example 1;

[0055] Figure 5 Performance comparison of the lithium copper half-cell prepared in Example 3;

[0056] Figure 6 A performance comparison of the negative electrode-free lithium metal batteries prepared in Application Example 1 and Application Example 4;

[0057] Figure 7 The performance of the negative electrode lithium metal batteries prepared in Application Example 1 and Comparative Example 1 is compared. Detailed Implementation

[0058] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0059] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0060] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0061] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0062] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0063] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0064] In a first aspect, the present invention provides a method for preparing a halide-doped carbon framework, comprising the following steps:

[0065] The halide is added to ethanol and then subjected to magnetic stirring or ultrasonic treatment to obtain a halide solution;

[0066] The carbon skeleton was placed in a solution of halides and allowed to stand to obtain a halide-doped carbon skeleton.

[0067] In a specific embodiment of the present invention, the carbon skeleton is selected from graphite paper, graphene, carbon nanotubes, and carbon fiber felt (with an areal density of 10 g / m²). 2 One of the following: 0.1mm thick carbon fiber paper (0.1mm thick, 80% porosity), carbon cloth, hard carbon, soft carbon, and porous carbon.

[0068] The porous structure of the carbon framework used in this invention provides uniform nucleation sites for lithium metal deposition, inhibits lithium dendrite growth, and reduces the risk of short circuits caused by uneven lithium deposition. The porous carbon framework also has a large specific surface area (e.g., graphene can reach 2630 m²). 2 The carbon framework ( / g) can promote rapid lithium-ion diffusion and reduce local current density. Simultaneously, the carbon framework can further enhance electrochemical performance: highly conductive carbon materials (such as graphene and carbon nanotubes) can reduce the current collector's internal resistance (graphene's conductivity is approximately 10). 6S / m), improving battery rate performance; the carbon skeleton surface can form a stable solid electrolyte interface (SEI), reducing electrolyte decomposition and side reactions, and improving coulombic efficiency.

[0069] In specific embodiments of the present invention, halides include fluorides, chlorides, bromides, iodides, or interhalogen compounds.

[0070] In specific embodiments of the present invention, the fluoride includes tin fluoride, strontium fluoride, or tetrafluoroethylene (CF2CF2).

[0071] Chlorides include chloromethane (CH3Cl), vinyl chloride (CH2CHCl), or chlorobenzene (C6H5Cl);

[0072] Bromines include tin bromide, strontium bromide, bromoethane (C2H5Br), or bromobenzene (C6H5Br);

[0073] Iodides include strontium iodide or tin iodide;

[0074] Interhalogen compounds (compounds formed by different halogens sharing electron pairs) include iodine fluoride, bromine monofluoride, chlorine monofluoride, iodine chloride, bromine chloride, iodine bromide, iodine trifluoride, bromine trifluoride, chlorine trifluoride, iodine pentafluoride, bromine pentafluoride, chlorine pentafluoride, or iodine heptafluoride.

[0075] In a specific embodiment of the present invention, the settling time is 1 to 12 hours.

[0076] The halides used in this invention can all undergo redox reactions with dead lithium to "activate" dead lithium and can all optimize the formation of SEI, thereby improving battery performance and significantly extending battery cycle life.

[0077] In a second aspect, the present invention provides a halide-doped carbon framework prepared by the above-described preparation method.

[0078] In a third aspect, the present invention provides an application of the above-mentioned halide-doped carbon framework in the preparation of a cathodeless lithium metal battery or a lithium copper half-cell.

[0079] In a fourth aspect, the present invention provides a halide-doped carbon skeleton current collector for a negative electrode-free lithium metal battery, comprising the halide-doped carbon skeleton and copper foil rolled together.

[0080] In a fifth aspect, the present invention provides a method for preparing a negative electrode-free lithium metal battery, which is selected from any of the following methods:

[0081] Method 1, the steps include: using the halide-doped carbon framework current collector of the above-mentioned negative electrode-free lithium metal battery as the negative electrode material, using lithium-containing material as the positive electrode material, adding electrolyte for assembly, to obtain a negative electrode-free lithium metal battery.

[0082] Method 2 includes the following steps: adding a halide to an electrolyte and dissolving it evenly to obtain an electrolyte containing a halide; dropping the electrolyte containing a halide onto one side of a current collector composed of a carbon skeleton and copper foil that are rolled together (the carbon skeleton will adsorb the halide onto the carbon skeleton); using a lithium-containing material as the positive electrode material and dropping the electrolyte onto the positive electrode material side; assembling the battery to obtain the negative electrode-free lithium metal battery.

[0083] In specific embodiments of the present invention, lithium-containing materials include lithium iron phosphate, lithium cobalt oxide, ternary lithium, or lithium manganese oxide.

[0084] In a specific embodiment of the present invention, the carbon skeleton is selected from one of graphite paper, graphene, carbon nanotubes, carbon fiber felt, carbon fiber paper, carbon cloth, hard carbon, soft carbon, and porous carbon.

[0085] In specific embodiments of the present invention, halides include fluorides, chlorides, bromides, iodides, or interhalogen compounds.

[0086] In specific embodiments of the present invention, the fluoride includes tin fluoride, strontium fluoride, or tetrafluoroethylene (CF2CF2).

[0087] Chlorides include chloromethane (CH3Cl), vinyl chloride (CH2CHCl), or chlorobenzene (C6H5Cl);

[0088] Bromines include tin bromide, strontium bromide, bromoethane (C2H5Br), or bromobenzene (C6H5Br);

[0089] Iodides include strontium iodide or tin iodide;

[0090] Interhalogen compounds (compounds formed by different halogens sharing electron pairs) include iodine fluoride, bromine monofluoride, chlorine monofluoride, iodine chloride, bromine chloride, iodine bromide, iodine trifluoride, bromine trifluoride, chlorine trifluoride, iodine pentafluoride, bromine pentafluoride, chlorine pentafluoride, or iodine heptafluoride.

[0091] In a sixth aspect, the present invention provides a negative electrode-free lithium metal battery prepared by the above-described preparation method.

[0092] Example 1

[0093] A method for preparing a tin bromide-doped carbon framework:

[0094] (1) Dissolve tin bromide in 99% ethanol by volume and stir magnetically for 3 hours to completely dissolve the tin bromide. Control the concentration of tin bromide to 5 mM to obtain a uniform organic dispersion (i.e., tin bromide ethanol solution).

[0095] (2) A carbon fiber felt with a thickness of 100 μm (area density of 10 g / m²) is placed in the carbon fiber felt.2 It has a thickness of 0.1 mm and an area of ​​1.13 cm². 2 The carbon felt was placed in an ethanol solution of tin bromide and soaked for 12 h. The carbon felt was then removed and dried with ethanol to obtain a tin bromide-doped carbon skeleton with a loading of about 0.14 mg (calculated by the increase in the mass of the carbon felt before and after soaking).

[0096] Application Example 1

[0097] Fabrication of anode-free lithium metal batteries:

[0098] (1) Using lithium iron phosphate sheets as the positive electrode material, the tin bromide-doped carbon framework prepared in Example 1 was combined with copper foil (the area of ​​the copper foil was 1.13 cm²). 2 A lithium metal battery without a negative electrode (i.e., LFP-SnBr2@CP@Cu) was assembled using a negative electrode current collector (with a thickness of 0.01 mm) and a mixed solvent containing 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1 vol.% LiNO3 in ethylene glycol dimethyl ether (DME), and 1,3-dioxolane (DOL) (DME and DOL in a volume ratio of 1:1).

[0099] Preparation of the negative electrode current collector: A tin bromide-doped carbon framework is directly brought into contact with copper foil, and then rolled using a roller mill to obtain a cut area of ​​1.13 cm². 2 A material with a thickness of 0.08 mm is used as the negative electrode current collector.

[0100] (2) Using lithium iron phosphate sheets as the positive electrode material, with a carbon skeleton and copper foil (the area of ​​the copper foil is 1.13 cm²). 2 A lithium metal battery without a negative electrode (i.e., LFP-CP@Cu) was assembled using a mixed solvent containing 1M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1 vol.% LiNO3 in ethylene glycol dimethyl ether (DME), and 1,3-dioxolane (DOL) (DME and DOL in a volume ratio of 1:1) as the electrolyte.

[0101] Preparation of negative electrode current collector: A carbon skeleton (carbon fiber felt, surface density 10 g / m²) is prepared. 2 It has a thickness of 0.1 mm and an area of ​​1.13 cm². 2 The material comes into direct contact with copper foil and is rolled by a roller press to obtain a cutting area of ​​1.13 cm². 2 A material with a thickness of 0.08 mm is used as the negative electrode current collector.

[0102] (3) Using lithium iron phosphate sheets as the positive electrode material, and copper foil (the area of ​​the copper foil is 1.13 cm²) 2A lithium metal battery without a negative electrode (i.e., LFP-Cu) is assembled using a mixed solvent containing 1M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1 vol.% LiNO3 in ethylene glycol dimethyl ether (DME), and 1,3-dioxolane (DOL) (DME and DOL in a volume ratio of 1:1) as the electrolyte.

[0103] A schematic diagram of the negative electrode current collector prepared using the tin bromide-doped carbon framework prepared in Example 1 is shown below. Figure 1 , Figure 1 In this context, 1 represents a halide (such as tin bromide), 2 represents a carbon skeleton, and 3 represents copper foil.

[0104] See the actual image of carbon fiber felt. Figure 2 The physical image of the negative electrode current collector composed of tin bromide-doped carbon framework and copper foil is shown below. Figure 3 .

[0105] Example 1

[0106] Voltage range: 2.5~3.8V; Current density: 1.0 mA / cm² 2 The performance (charge-discharge curves and coulombic efficiency) of the electrodeless lithium metal battery prepared in Example 1 was measured under the conditions of a charging cutoff voltage of 3.8V and a discharging cutoff voltage of 2.5V. The results are shown in [Figure 1]. Figure 4 .

[0107] from Figure 4 As can be seen from the data, the LFP-SnBr2@CP@Cu prepared using a tin bromide-doped carbon framework in Example 1 exhibits better cycling capacity (capacity of single-sided LFP) and stability than LFP-CP@Cu and LFP-Cu.

[0108] Application Example 2

[0109] Fabrication of anode-free lithium metal batteries:

[0110] (1) The carbon skeleton (carbon fiber felt, with a surface density of 10 g / m²) 2 It has a thickness of 0.1 mm and an area of ​​1.13 cm². 2 ) and copper foil (area 1.13cm²) 2 The material (with a thickness of 0.01mm) is in direct contact with the material and is then rolled by a roller press to obtain a cutting area of ​​1.13cm². 2 A material with a thickness of 0.8 mm is used as the negative electrode current collector.

[0111] (2) Weigh 5.57 mg of SnBr2 and add it to 4 mL of electrolyte to prepare a 5 mM tin bromide electrolyte. When making a coin cell, drop 50 μL of the tin bromide electrolyte onto a surface with an area of ​​1.13 cm². 2On the negative current collector, lithium iron phosphate electrode sheet is used as positive electrode material, and electrolyte is dropped onto the positive electrode material side, and then assembled into a battery.

[0112] The electrolyte is a mixed solvent containing 1M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1 vol.% LiNO3 in ethylene glycol dimethyl ether (DME), and 1,3-dioxolane (DOL) (the volume ratio of DME to DOL is 1:1).

[0113] Application Example 3

[0114] Preparation of lithium copper half-cells:

[0115] (1) Preparation of Li-SnBr2@CP@Cu: The tin bromide-doped carbon framework and copper foil (the area of ​​the copper foil is 1.13 cm²) prepared in Example 1 were used. 2 A half-cell was assembled using lithium tin bromide-doped carbon skeleton and copper foil as the positive electrode material (0.01 mm thick) and lithium foil (0.38 mm thick) as the negative electrode. The electrolyte was a mixed solution of FEC (dimethyl carbonate) and DMC (fluoroethylene carbonate) containing 1 M LiPF6, with a volume ratio of FEC to DMC of 1:4.

[0116] Preparation of the cathode material: Tin bromide-doped carbon framework is directly contacted with copper foil, and then rolled using a roller mill to obtain a cut area of ​​1.13 cm². 2 A material with a thickness of 0.08 mm was used as the positive electrode material.

[0117] (2) Preparation of Li-CP@Cu: using a carbon skeleton (carbon fiber felt, with a surface density of 10 g / m³) 2 It has a thickness of 0.1 mm and an area of ​​1.13 cm². 2 Add copper foil (area 1.13cm²) 2 Using lithium foil (0.38 mm thick) as the positive electrode material and lithium foil (0.01 mm thick) as the negative electrode, a half-cell with a lithium-carbon skeleton and copper foil is assembled (electrolyte: a mixed solution of FEC and DMC containing 1 M LiPF6, with a volume ratio of FEC to DMC of 1:4).

[0118] Preparation of the positive electrode material: Carbon fiber is directly brought into contact with copper foil, and then rolled using a roller mill to obtain a cut area of ​​1.13 cm². 2 A material with a thickness of 0.08 mm was used as the positive electrode material.

[0119] (3) Preparation of Li-Cu: using copper foil (with an area of ​​1.13 cm²) 2A half-cell with lithium copper foil (0.01 mm thick) was assembled using lithium foil (0.38 mm thick) as the positive electrode material and lithium foil (0.38 mm thick) as the negative electrode material. The electrolyte was a mixed solution of FEC and DMC containing 1 M LiPF6, with a volume ratio of FEC to DMC of 1:4.

[0120] Example 2

[0121] At a current density of 1.0 mA / cm² 2 The performance (coulombic efficiency) of the lithium copper half-cell prepared in Example 3 was measured under the conditions of a charging cutoff voltage of 1.2V and a discharge capacity of 1.13mAh. The results are shown in [Figure number missing]. Figure 5 .

[0122] from Figure 5 As can be seen, LFP-SnBr2@CP@Cu still maintains an 80% coulombic efficiency after 200 cycles. Figure 5 In contrast, LFP-Cu's coulombic efficiency begins to drop below 80% after 30 cycles, and LFP-CP@Cu's coulombic efficiency also begins to drop to 80% after 60 cycles. This demonstrates that halogen-modified carbon skeletons combined with copper foil as cathode materials significantly improve battery performance.

[0123] Example 2

[0124] Same as Example 1, except that the halide is iodine bromide; an iodine bromide-doped carbon framework was prepared.

[0125] Application Example 4

[0126] Similar to Application Example 1, except that the tin bromide-doped carbon framework was replaced with the iodine bromide-doped carbon framework prepared in Example 2, and LFP-IBr@CP@Cu was prepared.

[0127] Example 3

[0128] Voltage range: 2.5~3.8V; Current density: 1.0mA / cm² 2 The performance (charge-discharge curves and coulombic efficiency) of the electrodeless lithium metal batteries prepared in Application Examples 1 and 4 were measured under the conditions of a charging cutoff voltage of 3.8V and a discharging cutoff voltage of 2.5V. The results are shown in [Figure Number]. Figure 6 . Figure 6 The cyclic capacity is the capacity of the double-sided LFP.

[0129] Comparative Example 1

[0130] Cu(TFSI)2 (copper bis(trifluoromethanesulfonyl)imide) was dissolved in 99% ethanol by volume and stirred magnetically for 3 hours to ensure complete dissolution of copper bis(trifluoromethanesulfonyl)imide. The concentration of copper bis(trifluoromethanesulfonyl)imide was controlled at 5 mM to obtain a uniform organic dispersion (i.e., an ethanol solution of copper bis(trifluoromethanesulfonyl)imide).

[0131] Carbon fiber felt (area density of 10 g / m²) 2 It has a thickness of 0.1 mm and an area of ​​1.13 cm². 2 The carbon felt was immersed in an ethanol solution of copper bis(trifluoromethanesulfonyl)imide for 12 hours. The carbon felt was then removed and dried with ethanol to obtain a copper bis(trifluoromethanesulfonyl)imide-doped carbon skeleton with a loading of approximately 0.31 mg (calculated by the increase in the mass of the carbon felt before and after immersion).

[0132] Application Comparative Example 1

[0133] Fabrication of anode-free lithium metal batteries:

[0134] (1) Using lithium iron phosphate as the positive electrode material, a copper-doped carbon framework of bis(trifluoromethanesulfonyl)imide with copper foil (area 1.13 cm²) was prepared in Comparative Example 1. 2 A lithium metal battery without a negative electrode (i.e., LFP-Cu(TFSI)2@CP@Cu) was assembled using a negative electrode current collector (with a thickness of 0.01 mm) and a mixed solvent containing 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1 vol.% LiNO3 in ethylene glycol dimethyl ether (DME), and 1,3-dioxolane (DOL) (DME and DOL in a volume ratio of 1:1) as the electrolyte.

[0135] Preparation of the negative electrode current collector: A copper-doped carbon framework of bis(trifluoromethanesulfonyl)imide was directly contacted with copper foil, and then rolled using a roller press to obtain a cut area of ​​1.13 cm². 2 A material with a thickness of 0.08 mm is used as the negative electrode current collector.

[0136] Example of effect 4

[0137] Voltage range: 2.5~3.8V; Current density: 1.0 mA / cm² 2 The performance (charge-discharge curves and coulombic efficiency) of the electrodeless lithium metal battery prepared in Comparative Example 1 was measured under the conditions of a charging cutoff voltage of 3.8V and a discharging cutoff voltage of 2.5V. The results are shown in [Figure 1]. Figure 7 .

[0138] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a halide-doped carbon framework, characterized in that, Includes the following steps: The carbon framework is placed in a solution of halides and allowed to stand to obtain the halide-doped carbon framework. The concentration of the halide solution is 0.5~10mM.

2. The preparation method according to claim 1, characterized in that, The carbon skeleton is selected from one of graphite paper, graphene, carbon nanotubes, carbon fiber felt, carbon fiber paper, carbon cloth, hard carbon, soft carbon, and porous carbon.

3. The preparation method according to claim 1, characterized in that, The halides include fluorides, chlorides, bromides, iodides, or interhalogen compounds.

4. The preparation method according to claim 3, characterized in that, The fluoride includes tin fluoride, strontium fluoride, or tetrafluoroethylene; And / or, the chloride includes chloromethane, vinyl chloride, or chlorobenzene; And / or, the bromide includes tin bromide, strontium bromide, bromoethane, or bromobenzene; And / or, the iodide includes strontium iodide or tin iodide; And / or, the interhalogen compounds include iodine fluoride, bromine monofluoride, chlorine monofluoride, iodine chloride, bromine chloride, iodine bromide, iodine trifluoride, bromine trifluoride, chlorine trifluoride, iodine pentafluoride, bromine pentafluoride, chlorine pentafluoride, or iodine heptafluoride.

5. A halide-doped carbon framework prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the halide-doped carbon framework of claim 5 in the preparation of a cathodeless lithium metal battery or a lithium copper half-cell.

7. A halide-doped carbon framework current collector for a negative electrode-free lithium metal battery, characterized in that, Includes the halide-doped carbon skeleton and copper foil of claim 5, which are rolled together.

8. A method for preparing a negative electrode-free lithium metal battery, characterized in that, Choose any one of the following methods: Method 1, the steps include: Using the halide-doped carbon framework current collector of the electrodeless lithium metal battery as described in claim 7 as the negative electrode material, and lithium-containing material as the positive electrode material, an electrolyte is added for assembly to obtain the electrodeless lithium metal battery. Method 2, the steps include: adding the halide to the electrolyte, dissolving it evenly to obtain an electrolyte containing the halide; An electrolyte containing halides is dropped onto one side of a current collector composed of a carbon skeleton and copper foil that are rolled together. A lithium-containing material is used as the positive electrode material, and an electrolyte is dropped onto the positive electrode material side. The assembly process yields the negative electrode-free lithium metal battery.

9. The method for preparing a negative electrode-free lithium metal battery according to claim 8, characterized in that, The lithium-containing materials include lithium iron phosphate, lithium cobalt oxide, ternary lithium, or lithium manganese oxide.

10. A negative electrode-free lithium metal battery prepared by the preparation method according to any one of claims 8 to 9.

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