Multifunctional metal-free negative electrode and preparation method and application thereof

Abstract

The invention relates to a multifunctional metal-free negative electrode and a preparation method and application thereof, and belongs to the technical field of coatings. The method comprises the following four steps: cleaning pretreatment of a carbon material, acidification of the carbon material, modification of the carbon material with regulation and control of the metallophilic and crystal growth orientation, and cleaning and drying of the carbon material with co-modification with regulation and control of the metallophilic and crystal growth orientation. The one-pot hydrothermal synthesis method is adopted for preparation, the process is simple and mature, raw materials are easy to obtain, the cost is low, the in-situ metallophilic and crystal growth orientation regulation co-modification effect is good, and industrialization is easy. The multifunctional metal-free negative electrode prepared by the invention has multiple functions of high specific surface area, excellent conductivity, excellent metal affinity and controllable crystal growth orientation, can be used for simultaneously solving the problems of dendritic crystal generation, failed metal growth and volume expansion of a metal battery negative electrode, and is easy to popularize and apply.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and in particular relates to a multifunctional metal-free negative electrode and a preparation method and application thereof. Background Art

[0002] The rapid development of social economy has put forward higher energy density, lower cost, higher safety and more stable requirements for energy storage devices. However, the energy density of traditional ion batteries (such as lithium-ion batteries, sodium-ion batteries, etc.) widely used in portable electronic devices, electric vehicles and energy storage systems has reached its limit, and it is difficult to meet the demand for higher energy density of energy storage devices in these application fields. The use of metal negative electrodes with high theoretical specific capacity (such as lithium (3860 mAh g –1 ), sodium (1166 mAhg –1 ), potassium (686 mAh g –1 )、Magnesium(2205 mAh g –1 ), zinc (820 mAh g –1 )、Aluminum(2980 mAh g –1 ) to replace the graphite anode of traditional ion batteries (372 mAh g –1 ), which can significantly improve the energy density of the resulting metal battery to meet the market's urgent demand for high-energy-density battery systems. Therefore, the research on metal batteries, which are known for their high energy density, has received great attention worldwide.

[0003] At present, metal batteries that directly use metals as negative electrodes still face many problems and challenges, making it difficult to achieve large-scale application. For example, uneven initial metal deposition and unstable solid electrolyte interface film (SEI film) will aggravate the formation and growth of metal dendrites, leading to a series of problems such as the continuous accumulation of failed metals (such as dead lithium, dead sodium, dead potassium, etc.), volume expansion of metal negative electrodes, continuous consumption of electrolytes, battery failure or short circuit, etc., resulting in low Coulombic efficiency, fast capacity decay, poor cycle stability and low safety of metal battery systems. In order to solve the above problems, a lot of research work has focused on: (i) optimizing the chemical properties of the electrode and electrolyte interface; (ii) optimizing electrolyte components and additives; (iii) constructing artificial SEI films; (iv) developing solid electrolytes, etc. Although these solutions have achieved effective improvements on metal batteries to a certain extent, their limitation is that they still need to use extremely active metals (such as lithium, sodium, potassium metals, etc.) as negative electrodes, which poses a great safety hazard. To this end, in addition to optimizing the design of electrolyte components and additives and regulating the interface properties of electrodes and electrolytes, designing a metal-free carrier for the negative electrode of metal batteries represents an important research direction in this field.

[0004] In recent years, with the rise of carbon paper, carbon cloth, carbon nanotubes, carbon nanofibers, graphite, graphitized carbon, graphene, and carbon-based materials derived from carbon-containing materials (such as covalent organic frameworks (COF), metal organic frameworks (MOF), two-dimensional transition metal carbides (MXenes), biomass, etc.), their excellent nanoscale porous structure, good conductivity, high specific surface area and other advantages have made them quickly become a research hotspot and focus in the field of electrochemical energy storage technology, especially their application in the design of metal-free negative electrode carriers for metal batteries has received great attention. Chinese patent CN114906835A "Carbon materials and preparation methods thereof and lithium metal batteries" discloses an amorphous carbon material obtained by sintering and carbonizing a carbon-containing polymer, and uses the high electronic conductivity of the carbon material to achieve the suppression of dead lithium, lithium dendrites, etc. in the lithium deposition layer on the negative electrode side of the lithium metal battery, and reduce the consumption of electrolyte by the interface reaction of the battery negative electrode. Chinese patent CN118507720A "A negative electrode material and its preparation method and application" discloses a three-dimensional porous carbon negative electrode, in which a lithium material layer and a biomass-based porous carbon material layer are sequentially arranged on the surface of the three-dimensional carbon material matrix. Among them, the three-dimensional carbon skeleton provides a higher specific surface area to adjust the lithium ion flux distribution, reduce the local current density, and guide the uniform deposition of lithium, while the biomass-based porous carbon material has a highly developed pore structure, which provides an effective diffusion channel for lithium ions, so that the lithium deposition rate is uniform, thereby reducing the formation of lithium dendrites. However, conventional carbon materials are usually lithium-phobic (i.e., lack sites for inducing uniform nucleation of lithium), resulting in a high lithium nucleation overpotential, uneven deposition and stripping of lithium on the negative electrode, and the formation of lithium dendrites and inactivated lithium, which ultimately leads to poor electrochemical performance of metal batteries. In order to overcome the lithium-phobicity of carbon materials, their surfaces can be modified by lithium-philicity, and lithium-philic groups can be introduced to provide nucleation sites for lithium deposition, so as to achieve uniform deposition and stripping of lithium. Chinese patent CN118572040A "A lithium metal battery negative electrode and its preparation method and lithium metal battery" discloses a lightweight porous carbon-based material based on polyamic acid auxiliary construction as a lithium-philic composite negative electrode for lithium metal batteries. Nitrogen and oxygen elements are introduced on the surface of lightweight porous carbon fibers as directional nucleation sites for electrochemical deposition of metal oxides. The abundant lithium-philic sites (nitrogen, metal oxides) in the porous carbon skeleton effectively inhibit the growth and volume expansion of lithium dendrites. On the other hand. The final morphology of metal deposition essentially depends on the preferred orientation of its crystal growth, which affects the growth and volume expansion of dendrites. Taking metallic lithium as an example, the (110) crystal plane is the preferred growth crystal plane during lithium deposition. However, thermodynamic studies have shown that lithium metal is very easy to form dendrites along the (110) crystal plane. Therefore, regulating the preferred growth orientation of lithium metal is also an important research direction for inhibiting dendrite growth and improving the performance of its metal battery. Song et al. proposed a method of developing a composite negative electrode of yttrium trifluoride and polymethyl methacrylate by synergistic regulation of SEI mechanics and crystal orientation.Yttrium-doped lithium metal is generated in situ by reacting the composite material with lithium metal, which reduces the surface energy of the lithium (200) crystal plane and adjusts the preferred crystal orientation from the traditional (110) plane to the (200) plane during lithium deposition, thereby inhibiting the growth of dendrites and achieving dense and smooth lithium deposition (Nat. Commun. 2024, 15, 4454).

[0005] However, the metal-free carrier design of metal battery negative electrode has a single modification function, complex process, and is difficult to achieve large-scale production and application. It still faces huge challenges in solving the dendrite generation, failed metal growth and volume expansion of the negative electrode, and thus improving the coulombic efficiency, cycle stability, and safety of metal batteries. Therefore, it is urgent to develop a multifunctional metal-free negative electrode with simple preparation process, low cost, high specific surface area, excellent conductivity, excellent metal affinity, and controllable crystal growth orientation, so as to achieve a comprehensive improvement in the coulombic efficiency, cycle life, safety and other performance of high energy density metal batteries. Summary of the invention

[0006] The purpose of the present invention is to solve the deficiencies of the prior art and to provide a multifunctional metal-free negative electrode and a preparation method and application thereof.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows: The first object of the present invention is to provide a multifunctional metal-free negative electrode which has high specific surface area, excellent electrical conductivity, excellent metal affinity, and controllable crystal growth orientation.

[0008] The second object of the present invention is to provide a simple and easy one-pot hydrothermal synthesis method of the multifunctional metal-free negative electrode.

[0009] The third object of the present invention is to provide an application of the multifunctional metal-free negative electrode, that is, a method of using the multifunctional metal-free negative electrode as the negative electrode of a metal battery system (including lithium, sodium, potassium, magnesium, zinc and aluminum metal batteries, etc.) to significantly improve the electrochemical performance (including coulombic efficiency, cycle life and safety, etc.) of the resulting metal battery.

[0010] A method for preparing a multifunctional metal-free negative electrode comprises the following steps: Step 1: Cleaning and pretreatment of carbon materials: ultrasonically clean the carbon materials with dilute hydrochloric acid, acetone, and deionized water for 0.5 to 2 hours and then dry them; Step 2, acidification of the carbon material: the carbon material treated in step 1 is treated with mixed acid at 30-80° C. for 1-6 hours, washed with deionized water until neutral, and then dried; The mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; Step 3, co-modification of the metal-philic and crystal growth orientation regulation of the carbon material: adding the carbon material treated in step 2 to a reaction medium containing both a metal-philic dopant and a crystal growth orientation regulator, and reacting at 100 to 200° C. for 6 to 48 hours; The metal-philic dopant is a nitrogen dopant, and the amount used is 0.1 to 10 mol L -1 ; The crystal growth orientation regulator is lanthanum dopant, and the dosage is 0.05~10 mol L -1 ; The reaction medium is at least one of deionized water, methanol, ethanol, ethylene glycol, N,N-dimethylformamide, and N,N-dimethylacetamide; Step 4, cleaning and drying of the metal-affinity and crystal growth orientation regulated co-modified carbon material: take out the reacted carbon material, wash it with deionized water until it is neutral, and dry it to obtain the in-situ metal-affinity and crystal growth orientation regulated co-modified carbon material, which is a multifunctional metal-free negative electrode.

[0011] Further, in step 1, the carbon material is at least one of carbon paper, carbon cloth, carbon nanotubes, carbon nanofibers, graphite, graphitized carbon, graphene, and carbon-based materials derived from carbon-containing substances; The carbon-based materials derived from carbon-containing substances include covalent organic frameworks, metal organic frameworks, two-dimensional transition metal carbides and biomass.

[0012] Furthermore, in step three, the nitrogen dopant is at least one of urea, ammonia water, hydrazine hydrate, ethylenediamine, ammonium fluoroborate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, melamine, and nitrogen-containing phenanthroline.

[0013] Further, in step three, the lanthanum dopant is at least one of lanthanum chloride, lanthanum basic carbonate, lanthanum fluoride and lanthanum nitrate.

[0014] The present invention also provides a multifunctional metal-free negative electrode prepared by the preparation method of the multifunctional metal-free negative electrode.

[0015] The present invention also provides a metal battery comprising the multifunctional metal-free negative electrode.

[0016] Furthermore, the metal battery is a lithium, sodium, potassium, magnesium, zinc or aluminum metal battery.

[0017] Furthermore, it includes a shell, a positive electrode, a negative electrode and a diaphragm installed in the shell; the diaphragm is arranged between the positive electrode and the negative electrode; the gap between the positive electrode and the diaphragm, and the gap between the negative electrode and the diaphragm are filled with electrolyte; the negative electrode adopts the above-mentioned multifunctional metal-free negative electrode.

[0018] Furthermore, the separator is a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene-polyethylene composite porous membrane, a cellulose porous membrane, a glass fiber porous membrane, a polyester membrane, a polyimide membrane, a polyamide membrane, ceramics, nylon or asbestos paper.

[0019] In step 3 of the present invention, the metal-philic dopant is a nitrogen dopant, and the amount used is 0.1 to 10 mol L -1 The crystal growth orientation regulator is lanthanum dopant, and the dosage is 0.05~10 mol L -1 The above dosage is calculated based on the volume of the reaction medium.

[0020] In step three of the present invention, there is no specific restriction on the ratio of the amount of the reaction medium to the amount of the carbon material, as long as the reaction can be achieved.

[0021] The present invention does not impose any particular limitation on the specific drying methods in steps 1, 2, and 4, and conventional drying methods may be used.

[0022] The present invention proposes a method for preparing a multifunctional metal-free negative electrode with high specific surface area, excellent electrical conductivity, excellent metal-affinity characteristics, and controllable crystal growth orientation by combining a carbon material with high specific surface area and high electrical conductivity with a metal-affinity site design and a metal deposition crystal surface control strategy through a one-pot hydrothermal synthesis. Specifically, the present invention proposes a method for in-situ metal-affinity and crystal growth orientation control co-modification of a carbon material with high specific surface area and high electrical conductivity by simultaneously introducing a metal-affinity dopant and a crystal growth orientation control agent during a one-pot hydrothermal reaction at high temperature and high pressure. The obtained in-situ metal-affinity and crystal growth orientation control co-modified carbon material has the multifunctionality of high specific surface area, excellent electrical conductivity, excellent metal-affinity characteristics, and controllable crystal growth orientation, and can be used to simultaneously solve the problems of dendrite generation, failed metal growth, and volume expansion of the negative electrode of metal batteries.

[0023] At the same time, the present invention also proposes a method for using the multifunctional metal-free negative electrode as the negative electrode of a metal battery (including lithium, sodium, potassium, magnesium, zinc, aluminum metal batteries, etc.) to significantly improve the electrochemical performance (including coulombic efficiency, cycle life and safety, etc.) of the resulting metal battery.

[0024] In order to overcome the shortcomings of the existing technical means of metal-free negative electrodes of metal batteries, such as single modification function, complex process, and difficulty in large-scale production and application, and thus solve the problems existing in metal batteries (such as capacity decay, low coulombic efficiency, volume expansion, short cycle life, poor safety, etc.), the present invention provides a metal-free negative electrode with simple process, low cost, high specific surface area, excellent conductive properties, excellent metal affinity, controllable crystal growth orientation and other multifunctionality, as well as its preparation method and application.

[0025] Compared with the prior art, the present invention has the following advantages: 1. The multifunctional metal-free negative electrode of the present invention is prepared by a one-pot hydrothermal synthesis method, which has a simple and mature process, readily available raw materials, low cost, good in-situ metal affinity and crystal growth orientation regulation co-modification effects, and is easy to industrialize.

[0026] 2. The multifunctional metal-free negative electrode of the present invention has a high specific surface area (> 10 m 2 g -1 ) and high conductivity (> 10S m -1 ) is based on carbon materials, which can effectively reduce the local current density on the electrode surface, inhibit the generation of metal dendrites, the growth of failed metals and volume expansion.

[0027] 3. The multifunctional metal-free negative electrode of the present invention introduces metal-philic dopants to modify the high specific surface area and high conductivity carbon material, which can provide nucleation sites for metal deposition on the electrode surface, reduce the nucleation overpotential, enhance metal-philicity, and further inhibit the generation of metal dendrites, the growth of failed metals, and volume expansion.

[0028] 4. The multifunctional metal-free negative electrode of the present invention introduces a crystal growth orientation regulator to modify the high specific surface area and high conductivity carbon material, and can generate a reduced state regulator in situ on the electrode surface through electrochemical reduction to reduce the surface energy of the metal high-index crystal plane (such as lithium metal (200) crystal plane), so that the preferred growth crystal plane of metal deposition is transformed from a low-high-index crystal plane (such as lithium metal (110) crystal plane) to a high-index crystal plane (such as lithium metal (200) crystal plane), promote the two-dimensional deposition of the metal, and further inhibit the generation of metal dendrites, the growth of failed metals and volume expansion.

[0029] 5. When the multifunctional metal-free negative electrode of the present invention is used as the negative electrode of a metal battery (including lithium, sodium, potassium, magnesium, zinc, aluminum metal batteries, etc.), it can synergistically inhibit the formation of dendrites of metals such as lithium, sodium, and potassium, the growth of failed metals, and the volume expansion, thereby achieving a comprehensive improvement in electrochemical performance (including coulombic efficiency, cycle life, safety, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The SEM images of the negative electrode materials of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Example 1; wherein (a) is the SEM image of the copper foil of Comparative Example 1; (b) and (c) are both SEM images of the carbon cloth of Comparative Example 2; (d) and (e) are both SEM images of the nitrogen-doped modified carbon cloth of Comparative Example 3; (f) and (g) are both SEM images of the lanthanum-doped modified carbon cloth of Comparative Example 4; (h) and (i) are both SEM images of the nitrogen- and lanthanum-co-doped modified carbon cloth of Example 1; Figure 2XRD spectra of the negative electrode materials of Comparative Example 2, Comparative Example 3, Comparative Example 4 and Example 1; Figure 3 is the Raman spectra of the negative electrode materials of Comparative Example 2, Comparative Example 3, Comparative Example 4, and Example 1; Figure 4 This is the full XPS spectrum of the negative electrode materials of Comparative Example 2, Comparative Example 3, Comparative Example 4, and Example 1; Figure 5 The Li half-cells of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Example 1 were prepared at a current density of 0.5 mA cm -2 , the discharge surface capacity is 4 mAh cm -2 Discharge surface capacity-voltage curve under; Figure 6 The Li half-cells of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Example 1 were prepared at a current density of 3 mA cm -2 , the discharge surface capacity is 3 mAh cm -2 Cyclic test curve below; Figure 7 The Li half-cells of Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Example 1 were prepared at a current density of 3 mA cm -2 , the discharge surface capacity is 3 mAh cm -2 EIS test curves after different cycle times; (a) is the EIS graph of different Li-half cells at open circuit voltage; (b) is the EIS graph of different Li-half cells after 3 cycles of activation; (c) is the EIS graph of different Li-half cells after 50 cycles; (d) is the EIS graph of different Li-half cells after 100 cycles; Figure 8 1 is a cycle test curve of the LFP-full battery of Comparative Example 5, Comparative Example 6, Comparative Example 7, Comparative Example 8, Comparative Example 9 and Example 2 at a current of 0.5C; Fig. 9 These are the cycle test curves of the NCM811-full battery of Comparative Example 10, Comparative Example 11, Comparative Example 12, Comparative Example 13, Comparative Example 14, and Example 3 at a current of 0.5 C. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with embodiments.

[0032] Those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the art or the product specifications are used. If the manufacturer of the materials or equipment used is not specified, they are all conventional products that can be purchased.

[0033] The present invention provides a method for preparing a multifunctional metal-free negative electrode. Specifically, by simultaneously introducing a metal-loving dopant and a crystal growth orientation regulator into the reaction medium of a one-pot hydrothermal synthesis method, a carbon material with high specific surface area and high conductivity is subjected to in-situ metal-loving and crystal growth orientation regulation co-modification under high temperature and high pressure hydrothermal reaction conditions. The prepared in-situ metal-loving and crystal growth orientation regulation co-modified carbon material has the multifunctionality of high specific surface area, excellent electrical conductivity, excellent metal-loving characteristics, and controllable crystal growth orientation, and can be used as a metal-free negative electrode of a metal battery to solve the problems of dendrite generation, failed metal growth, and volume expansion.

[0034] The method for preparing the multifunctional metal-free negative electrode of the present invention is characterized by comprising the following specific steps: Step 1: Cleaning pretreatment of carbon materials: ultrasonically clean the carbon materials with dilute hydrochloric acid, acetone, and deionized water for 0.5 to 2 h and then dry them to remove stains on the surface of the carbon materials.

[0035] The carbon material is at least one of carbon paper, carbon cloth, carbon nanotubes, carbon nanofibers, graphite, graphitized carbon, graphene, and carbon-based materials derived from carbon-containing substances (covalent organic frameworks (COFs), metal organic frameworks (MOFs), two-dimensional transition metal carbides (MXenes), biomass, etc.) having high specific surface area and high conductivity.

[0036] Step 2, acidification of the carbon material: treat the carbon material with a mixed acid of concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1) at 30-80°C for 1-6 h, wash with deionized water until neutral and then dry to enhance the hydrophilicity of the carbon material.

[0037] Step three, co-modification of the metallophilicity and crystal growth orientation regulation of the carbon material: adding the acid-treated carbon material to a reaction medium containing both a metallophilic dopant and a crystal growth orientation regulator, and transferring the reactant system to a reactor, and reacting at 100-200 °C for 6-48 h.

[0038] The metal-philic dopant is a nitrogen dopant, and the amount used is 0.1 to 10 mol L -1 .

[0039] The nitrogen dopant is urea, ammonia (NH 3 H 2O), hydrazine hydrate (N 2 H 4 ·H 2 O), ethylenediamine (C 2 H 8 N 2 ), ammonium fluoroborate (NH 4 BF 4 ), ammonium phosphate (NH 4 ) 3 PO 4 )、ammonium hydrogen phosphate((NH 4 ) 2 HPO 4 ), diammonium phosphate (NH 4 H 2 PO 4 ), melamine (C 3 H 6 N 6 ), nitrogen-containing phenanthroline (PHN, C 12 H 8 N 2 ) etc.

[0040] The crystal growth orientation regulator is a lanthanum dopant, and the amount used is 0.05 to 10 mol L -1 .

[0041] The lanthanum dopant is lanthanum chloride (LaCl 3 · x H 2 O), lanthanum carbonate (LaCO 3 OH), lanthanum fluoride (LaF 3 )、Lanthanum nitrate(La(NO 3 ) 3 6H 2 O) etc.

[0042] Step 4, cleaning and drying of the metal-affinity and crystal growth orientation regulated co-modified carbon material: the carbon material after the hydrothermal reaction is washed with deionized water until it is neutral, and dried to obtain the final product, the in-situ metal-affinity and crystal growth orientation regulated co-modified carbon material (i.e., a multifunctional metal-free negative electrode).

[0043] The present invention also uses the in-situ metal-philic and crystal growth orientation-regulated co-modified carbon material as a multifunctional metal-free negative electrode of a metal battery to improve its electrochemical performance.

[0044] The metal battery includes at least one of lithium, sodium, potassium, magnesium, zinc, aluminum metal batteries, etc.; the structure of the metal battery includes a positive electrode, a negative electrode, a separator between the positive electrode and the negative electrode, an electrolyte filled in the gaps between the positive electrode, the negative electrode and the separator, and a shell. The specific steps are as follows: (i) Prepare the corresponding positive electrode according to different metal battery systems.

[0045] (ii) A multifunctional metal-free negative electrode of in-situ metal-philic and crystal growth orientation-regulated co-modified carbon material is prepared according to the preparation method of the present invention.

[0046] (iii) Under inert gas atmosphere conditions with controlled moisture and oxygen content < 1 ppm, the positive electrode, negative electrode, separator and electrolyte are encapsulated into a shell to assemble a metal battery.

[0047] The positive electrode is any one of the corresponding positive electrodes of a metal battery (lithium, sodium, potassium, magnesium, zinc, aluminum metal battery, etc.).

[0048] The negative electrode is a multifunctional metal-free negative electrode of in-situ metal-philic and crystal growth orientation-regulated co-modified carbon material prepared by the present invention.

[0049] The separator is at least one of polypropylene porous film (PP), polyethylene porous film (PE), polypropylene-polyethylene composite porous film (PP-PE), cellulose porous film, glass fiber porous film, polyester film (PET), polyimide film (PI), polyamide film (PA), ceramic, nylon, asbestos paper, etc.

[0050] The electrolyte is any one of the corresponding electrolytes of metal batteries (lithium, sodium, potassium, magnesium, zinc, aluminum and other metal batteries).

[0051] The metal battery is packaged in any of a button type, a cylindrical type, a square type, and a special shape.

[0052] The packaging shell of the metal battery is any one of a hard shell (steel shell, plastic shell, aluminum shell) and a soft shell (aluminum-plastic film).

[0053] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention belong to the protection scope of the present invention.

[0054] Comparative Example 1: Commercial copper foil current collector negative electrode (Cu) and its physical and chemical properties (i) Using commercial Cu current collector as negative electrode, the surface morphology was tested by scanning electron microscopy (SEM). Under the condition of inert gas atmosphere with controlled moisture and oxygen content < 1 ppm, Cu negative electrode, polypropylene-polyethylene composite porous film (PP-PE), lithium sheet (Li), 1 mol L -1 Lithium hexafluorophosphate (LiPF 6) dissolved in ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / dimethyl carbonate (DMC) (volume ratio 1:1:1) electrolyte packaged into LIR2025 button-type Li / / Cu half-cell. The assembled half-cell was electrochemically tested (voltage range of -0.5 to 1.0 V, current density of 0.5 to 3.0 mA cm -2 , discharge surface capacity is 3.0~4.0 mAh cm -2 , electrochemical impedance spectroscopy (EIS) frequency range is 10 mHz to 100 kHz, amplitude is 10 mV).

[0055] (ii) Result analysis: Since the Cu surface is smooth (such as Figure 1 a) Low specific surface area and poor lithium affinity. The assembled Li / / Cu half-cell exhibited a large nucleation overpotential of 64 mV during the first discharge (µ NOP )(like Figure 5 ), indicating that lithium is deposited unevenly on the Cu current collector and lithium dendrites are easily generated. During the charge and discharge cycle, the Li / / Cu half-cell has low coulombic efficiency, rapid capacity decay, and extremely poor cycle stability (only maintained for 20 cycles) (e.g. Figure 6 ), EIS impedance increases rapidly (such as Figure 7 ), indicating the growth of a large number of lithium dendrites and the accumulation of failed lithium on the Cu current collector with cycling. The above results confirm the extremely poor electrochemical performance of commercial Cu current collectors when used directly as negative electrodes for metal batteries.

[0056] Comparative Example 2: Commercial carbon cloth anode (CC) and its physical and chemical properties (i) Commercial CC was ultrasonically cleaned with dilute hydrochloric acid, acetone, and deionized water for 1 h, then dried, and treated with acid (mixed acid treatment was used, the mixed acid was a mixture of concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of concentrated sulfuric acid to concentrated nitric acid was 3:1) at 50°C for 4 h. After washing and drying, it was used as the negative electrode and characterized by SEM, X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS). Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, CC negative electrode, polypropylene-polyethylene composite porous film (PP-PE), lithium sheet (Li), 1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type Li / / CC half-cells. The assembled half-cells were subjected to relevant electrochemical tests under the same conditions.

[0057] (ii) Result analysis: Commercial CC is a three-dimensional continuous structural fabric composed of a large number of carbon fibers with a diameter of about 10 μm, which are integrated into one through a special weaving process. Figure 1 b and Figure 1 c), with a larger specific surface area than the Cu current collector. In the XRD test, CC showed a larger 2θ diffraction angle value (25.88°), a stronger diffraction peak intensity and a narrower diffraction peak width (such as Figure 2 ), indicating a higher degree of graphitization and smaller interplanar spacing on the fiber surface. In the Raman test, CC showed a smaller I D / I G Value (1.05) (e.g. Figure 3 ), indicating that the fiber surface has a high degree of order and fewer defects. In the XPS test, CC showed strong C (85.03 at.%) and O (14.97 at.%) element signals (such as Figure 4 ), indicating that a large number of oxygen-containing functional groups were introduced on the fiber surface after mixed acid treatment. Thanks to the higher specific surface area of ​​CC than Cu, the local current density on the electrode surface is reduced, slowing down the generation of lithium dendrites. Therefore, the nucleation overpotential of the Li / / CC half-cell during the first discharge is reduced to 10 mV (e.g. Figure 5 ), showing higher coulombic efficiency and better cycle stability (120 stable cycles) during the charge and discharge cycle (such as Figure 6 ), lower EIS impedance (such as Figure 7 ), indicating the suppressed growth of lithium dendrites and the accumulation of failed lithium on CC. However, due to the lack of lithium affinity on the CC surface and the function of regulating crystal growth orientation, its electrochemical performance as anode of metal batteries needs to be improved.

[0058] Comparative Example 3: Nitrogen-doped modified carbon cloth anode (NCC) and its physical and chemical properties (i) Commercial CC was ultrasonically cleaned with dilute hydrochloric acid, acetone, and deionized water for 1 h, then dried, and treated with acid (using mixed acid treatment, the mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1) at 50 °C for 4 h, then washed and dried. The acid-treated CC was added to a 4 mol L -1 The urea solution was placed at room temperature for 12 h and then transferred to a reactor for hydrothermal reaction at 180 °C for 24 h. After cooling to room temperature, it was washed and dried with deionized water to obtain a nitrogen-doped modified carbon cloth anode (NCC), which was characterized by SEM, XRD, Raman, and XPS. Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, the NCC anode, polypropylene-polyethylene composite porous film (PP-PE), lithium sheet (Li), 1 mol L -1 LiPF 6The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type Li / / NCC half-cells. The assembled half-cells were subjected to relevant electrochemical tests under the same conditions.

[0059] (ii) Result analysis: Compared with CC, the surface morphology of the NCC negative electrode after nitrogen doping is similar to that of CC, with no obvious changes (e.g. Figure 1 d and Figure 1 e). In the XRD test, the 2θ diffraction angle of NCC shifted to the low value direction to 25.68°, and the diffraction peak intensity did not change significantly, but the diffraction peak width became wider, indicating that the degree of graphitization on the fiber surface decreased and the interplanar spacing increased (e.g. Figure 2 ). In the Raman test, the I D / I G The value rises to 1.10, indicating that the order of the fiber surface decreases and the defect increases (e.g. Figure 3 In the XPS test, NCC showed obvious N (5.79 at.%) element signals (such as Figure 4 ), indicating that after hydrothermal nitrogen doping, its fiber surface has abundant lithium-philic active sites. Compared with CC, due to the reduced graphitization degree, increased interplanar spacing, reduced order, increased defectivity, and lithium-philicity brought by nitrogen doping, the nucleation overpotential of Li / / NCC half-cell at the first discharge is further reduced to 7.2 mV (e.g. Figure 5 ), showing further improved coulombic efficiency and improved cycle stability (215 stable cycles) during the charge and discharge cycle (e.g. Figure 6 ), reduced EIS impedance (e.g. Figure 7 ), indicating that the growth of lithium dendrites and the accumulation of failed lithium on NCC are further suppressed. However, since the NCC surface still lacks the function of regulating crystal growth orientation, its electrochemical performance as anode of metal batteries still needs to be further improved.

[0060] Comparative Example 4: Lanthanum-doped modified carbon cloth anode (LCC) and its physical and chemical properties (i) Commercial CC was ultrasonically cleaned with dilute hydrochloric acid, acetone, and deionized water for 1 h, then dried, and treated with acid (using mixed acid treatment, the mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1) at 50 °C for 4 h, then washed and dried. The acid-treated CC was added to a 0.1 mol L -1 LaCO 3OH aqueous solution, left to stand at room temperature for 12 h, then transferred to a reactor, hydrothermally reacted at 180 °C for 24 h, cooled naturally to room temperature, washed with deionized water and dried to obtain a lanthanum-doped modified carbon cloth anode (LCC), which was characterized by SEM, XRD, Raman, and XPS. Under an inert gas atmosphere with controlled moisture and oxygen content < 1 ppm, the LCC anode, polypropylene-polyethylene composite porous film (PP-PE), lithium sheet (Li), 1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type Li / / LCC half-cells. The assembled half-cells were subjected to relevant electrochemical tests under the same conditions.

[0061] (ii) Result analysis: Compared with CC, LaCO 3 OH particles are attached to its three-dimensional carbon fiber skeleton (e.g. Figure 1 f and Figure 1 g). In the XRD test, the 2θ diffraction angle of LCC shifted to the low value direction to 25.46°, and the diffraction peak intensity decreased and the diffraction peak width became wider, indicating that the degree of graphitization on the fiber surface decreased and the interplanar spacing increased (e.g. Figure 2 ). In addition, the XRD pattern of LCC shows that it can be attributed to LaCO 3 The diffraction peak of OH is similar to that of standard LaCO 3 The OH spectrum (JCPDS card number 26-0815) completely matches, indicating that LaCO has been successfully loaded on the fiber skeleton. 3 OH particles. In the Raman test, the I D / I G The value increased to 1.09, indicating that the order of the fiber surface decreased and the defect increased (e.g. Figure 3 In the XPS test, LCC showed obvious La (2.45 at.%) element signals, indicating that after hydrothermal lanthanum doping, its fiber surface has abundant crystal growth orientation regulation sites. Compared with CC, LCC has a reduced graphitization degree, increased interplanar spacing, reduced order, increased defectivity, and the crystal growth orientation regulation function brought by the doped lanthanum (lanthanum ions (La 3+ ) The elemental lanthanum generated by reduction during the first discharge can reduce the surface energy of the lithium metal (200) crystal plane, so that the preferred growth crystal plane orientation of lithium deposition changes from the (110) crystal plane to the (200) crystal plane, thereby promoting the two-dimensional deposition of lithium and inhibiting its dendrite growth). The nucleation overpotential of the Li / / LCC half-cell during the first discharge is further reduced to 8.5 mV (e.g. Figure 5), showing further improved Coulombic efficiency, improved cycling stability (220 stable cycles) during charge-discharge cycling (as Figure 6 ), and reduced EIS impedance (as Figure 7 ), indicating further inhibited growth of lithium dendrites and accumulation of failed lithium on LCC. However, due to the still lack of lithiophilicity on the LCC surface, its electrochemical performance as a metal battery anode still needs to be further improved.

[0062] Example 1: Nitrogen and lanthanum co-doped modified carbon cloth anode (NLCC) and its physical and chemical properties (i) The commercial CC was ultrasonically cleaned with dilute hydrochloric acid, acetone, and deionized water in sequence for 1 h and then dried, acid-treated at 50 °C (using a mixed acid treatment, the mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1) for 4 h and then washed and dried. The acid-treated CC was added to an aqueous solution containing 4 mol L -1 urea and 0.1 mol L -1 LaCl 3 · x H 2 O, left standing at room temperature for 12 h and then transferred to a reaction kettle, hydrothermally reacted at 180 °C for 24 h, naturally cooled to room temperature and then washed and dried with deionized water to obtain a nitrogen and lanthanum co-doped modified carbon cloth anode (NLCC), and its SEM, XRD, Raman, and XPS were characterized. Under the condition of an inert gas atmosphere with the moisture and oxygen content < 1 ppm controlled, the NLCC anode, polypropylene-polyethylene composite porous film (PP-PE), lithium sheet (Li), and an electrolyte in which 1 mol L -1 LiPF 6 is dissolved in EC / EMC / DMC (volume ratio 1:1:1) were encapsulated into a LIR2025 button-type Li / / NLCC half-cell. The assembled half-cell was subjected to relevant electrochemical tests under the same conditions.

[0063] (ii) Result analysis: Compared with CC, for the NLCC anode after nitrogen and lanthanum co-doping, it was observed that LaCO 3 OH particles grew uniformly on its three-dimensional carbon fiber skeleton (as Figure 1 h and Figure 1 i), and its surface morphology characteristics showed a more uniform LaCO Figure 1 f and Figure 1 g) than that of LCC (as 3OH particle distribution. In the XRD test, compared with NCC and LCC, the 2θ diffraction angle of NLCC shifts to a lower value, and the diffraction peak intensity is further reduced, and the diffraction peak width is further broadened, indicating that nitrogen-lanthanum co-doping can significantly reduce the graphitization degree of the carbon fiber surface and significantly increase the interplanar spacing compared with single nitrogen (or lanthanum) doping (e.g. Figure 2 ). At the same time, similar to LCC, NLCC shows a 3 The diffraction peak of OH indicates that LaCO has been successfully loaded on the fiber skeleton. 3 OH particles. In the Raman test, compared with NCC and LCC, NLCC has a higher I D / I G The value further increases, indicating that nitrogen-lanthanum co-doping can significantly reduce the order of the carbon fiber surface and increase the defectivity more significantly than single nitrogen (or lanthanum) doping (e.g. Figure 3 ). In the XPS test, NLCC showed obvious N (7.20 at.%) and La (1.06 at.%) element signals, proving that nitrogen-lanthanum co-doping has been successfully performed, and indicating that after hydrothermal nitrogen-lanthanum co-doping, its fiber surface has both abundant lithium-philic active sites and crystal growth orientation regulation sites. Compared with NCC and LCC, due to the further reduced graphitization degree, increased interplanar spacing, reduced order, increased defectivity, and the lithium-philicity brought by the simultaneous doping of nitrogen and the crystal growth orientation regulation function brought by the doping of lanthanum, the nucleation overpotential of the Li / / NLCC half-cell at the first discharge is further reduced to 6 mV (such as Figure 5 ), showing further improved coulombic efficiency and improved cycle stability (280 stable cycles) during the charge and discharge cycle (such as Figure 6 ), reduced EIS impedance (e.g. Figure 7 ), indicating that the growth of lithium dendrites and the accumulation of failed lithium on NLCC are further suppressed. So far, combined with the high specific surface area and high conductivity of carbon materials and the lithium affinity brought by nitrogen doping and the crystal growth orientation regulation function brought by lanthanum doping, nitrogen-lanthanum co-doped modified carbon cloth has been proved to be a multifunctional metal-free negative electrode to improve the electrochemical performance of metal batteries.

[0064] Comparative Example 5: LFP / / Li metal battery based on commercial lithium metal anode (Li) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, a Li negative electrode, a polypropylene-polyethylene composite porous film (PP-PE), and a LiFePO 4 (LFP) cathode sheet (material mass ratio: LFP / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 17.64 mg cm -2)、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type LFP / / Li metal batteries. The assembled batteries were electrochemically tested (voltage range 2.0-4.0 V, 0.1 C activation, 0.5 C cycling, 1 C current defined as 170 mA g -1 ).

[0065] (ii) Result analysis: The extremely strong reactivity of lithium metal (due to its lowest redox potential) and its host-free characteristics (due to its infinite volume change during oxidation-reduction) inevitably lead to continuous reactions between it and the electrolyte and uncontrollable growth of lithium dendrites, resulting in extremely poor cycle stability of LFP / / Li metal batteries. Therefore, when the assembled LFP / / Li metal battery is cycled at 0.5 C, the discharge specific capacity decays rapidly and is accompanied by a large fluctuation in coulombic efficiency. After about 170 cycles, the capacity decays rapidly to 0 (e.g. Figure 8 illustration).

[0066] Comparative Example 6: LFP / / Cu metal battery based on commercial copper foil current collector anode (Cu) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, a Cu negative electrode, a polypropylene-polyethylene composite porous film (PP-PE), and a LiFePO 4 (LFP) cathode sheet (material mass ratio: LFP / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 17.64 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type LFP / / Cu metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0067] (ii) Result analysis: Due to the smooth surface, low specific surface area and poor lithium affinity of the Cu negative electrode, it is impossible to effectively guide the uniform deposition and stripping of lithium, resulting in the generation of a large number of lithium dendrites and the accumulation of failed lithium during the cycle. Therefore, the coulombic efficiency of the assembled LFP / / Cu metal battery fluctuated greatly during the 0.5 C cycle, and the discharge specific capacity decayed rapidly to 0 (such as Figure 8 illustration).

[0068] Comparative Example 7: LFP / / CC metal battery based on commercial carbon cloth anode (CC) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, the CC anode, polypropylene-polyethylene composite porous film (PP-PE), LiFePO 4 (LFP) cathode sheet (material mass ratio: LFP / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 17.64 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type LFP / / CC metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0069] (ii) Result analysis: Compared with Li and Cu negative electrodes, CC negative electrodes have a higher specific surface area, which can reduce the local current density on the electrode surface to a certain extent, reduce the nucleation overpotential of lithium deposition, and thus slow down the growth of lithium dendrites and the accumulation of failed lithium. Therefore, the stability of the assembled LFP / / CC metal battery at 0.5 C cycle is improved, and the discharge specific capacity and capacity retention rate after 300 cycles are 77.74 mAh g -1 and 61.58% (e.g. Figure 8 ). However, due to the lack of lithium affinity on the CC surface and the function of regulating crystal growth orientation, its electrochemical performance as anode of metal batteries needs to be improved.

[0070] Comparative Example 8: LFP / / NCC metal battery based on nitrogen-doped modified carbon cloth anode (NCC) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, NCC anode, polypropylene-polyethylene composite porous film (PP-PE), LiFePO 4 (LFP) cathode sheet (material mass ratio: LFP / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 17.64 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type LFP / / NCC metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0071] (ii) Result analysis: Compared with CC, NCC further reduces the local current density on the electrode surface and the nucleation overpotential of lithium deposition due to its reduced graphitization degree, increased interplanar spacing, reduced order, increased defectivity, and lithium affinity brought by nitrogen doping, thereby further slowing down the growth of lithium dendrites and the accumulation of failed lithium. Therefore, the stability of the assembled LFP / / NCC metal battery at 0.5 C cycle is further improved, and the discharge specific capacity and capacity retention rate after 300 cycles are 101.34 mAh g -1 and 78.14% (e.g. Figure 8 ). However, since the NCC surface still lacks the function of regulating the crystal growth orientation, its electrochemical performance as anode of metal batteries still needs to be further improved.

[0072] Comparative Example 9: LFP / / LCC metal battery based on lanthanum-doped modified carbon cloth anode (LCC) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, the LCC anode, polypropylene-polyethylene composite porous film (PP-PE), LiFePO 4 (LFP) cathode sheet (material mass ratio: LFP / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 17.64 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type LFP / / LCC metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0073] (ii) Result analysis: Compared with CC, due to its reduced graphitization degree, increased interplanar spacing, reduced order, increased defectivity, and the crystal growth orientation regulation function brought by the doped lanthanum, LCC further reduces the local current density on the electrode surface and the nucleation overpotential of lithium deposition, thereby further slowing down the growth of lithium dendrites and the accumulation of failed lithium. Therefore, the stability of the assembled LFP / / LCC metal battery at 0.5 C cycle is further improved, and the discharge specific capacity and capacity retention rate after 300 cycles are 100.03 mAh g -1 and 77.33% (e.g. Figure 8 ). However, due to the lack of lithium affinity on the surface of LCC, its electrochemical performance as anode of metal batteries still needs to be further improved.

[0074] Example 2: LFP / / NLCC metal battery based on nitrogen and lanthanum co-doped modified carbon cloth anode (NLCC) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, the NLCC anode, polypropylene-polyethylene composite porous film (PP-PE), LiFePO 4 (LFP) positive electrode sheet (ingredient mass ratio: LFP / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 17.64 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type LFP / / NLCC metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0075] (ii) Result analysis: Compared with NCC and LCC, NLCC further reduces the local current density on the electrode surface and the nucleation overpotential of lithium deposition due to its further reduced graphitization degree, increased interplanar spacing, reduced order, increased defectivity, and the lithium affinity brought by the doped nitrogen and the crystal growth orientation regulation function brought by the doped lanthanum, thereby further slowing down the growth of lithium dendrites and the accumulation of failed lithium. Therefore, the stability of the assembled LFP / / NLCC metal battery at 0.5 C cycle is further improved, and the discharge specific capacity and capacity retention rate after 300 cycles are 108.32 mAh g -1 and 81.84% (e.g. Figure 8 ). Thus, combined with the high specific surface area and high conductivity of carbon materials and the lithium affinity brought by the nitrogen doping and the crystal growth orientation regulation function brought by the lanthanum doping, nitrogen and lanthanum co-doped modified carbon cloth has been proved to be a multifunctional metal-free negative electrode to improve the electrochemical performance of metal batteries.

[0076] Comparative Example 10: NCM811 / / Li metal battery based on commercial lithium metal anode (Li) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, a Li anode, a polypropylene-polyethylene composite porous film (PP-PE), and a polycrystalline 811 nickel cobalt manganese oxide (NCM811) cathode sheet (material mass ratio: NCM811 / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 13.53 mg cm -2 )、1 mol L -1 LiPF 6The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type NCM811 / / Li metal batteries. The assembled batteries were electrochemically tested (voltage range 2.0-4.3 V, 0.1 C activation 5 times, 0.5 C cycle, 1 C current defined as 200 mA g -1 ).

[0077] (ii) Analysis of results: The extremely strong reactivity of lithium metal (due to its lowest redox potential) and its host-free characteristics (due to its infinite volume change during oxidation-reduction) inevitably lead to continuous reactions between it and the electrolyte and uncontrollable growth of lithium dendrites, resulting in extremely poor cycle stability of NCM811 / / Li metal batteries. Therefore, when the assembled NCM811 / / Li metal battery is cycled at 0.5 C, the discharge specific capacity decays rapidly and is accompanied by a large fluctuation in coulombic efficiency. After about 220 cycles, the capacity decays rapidly to 0 (e.g. Fig. 9 illustration).

[0078] Comparative Example 11: NCM811 / / Cu metal battery based on commercial copper foil current collector negative electrode (Cu) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, a Cu negative electrode, a polypropylene-polyethylene composite porous film (PP-PE), and a polycrystalline 811 nickel cobalt manganese oxide (NCM811) positive electrode sheet (material mass ratio: NCM811 / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 13.53 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type NCM811 / / Cu metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0079] (ii) Analysis of results: Due to the smooth surface, low specific surface area and poor lithium affinity of the Cu negative electrode, it is impossible to effectively guide the uniform deposition and stripping of lithium, resulting in the generation of a large number of lithium dendrites and the accumulation of failed lithium during the cycle. Therefore, the coulombic efficiency of the assembled NCM811 / / Cu metal battery fluctuated greatly during the 0.5 C cycle, and the discharge specific capacity decayed rapidly to 0 (e.g. Fig. 9 illustration).

[0080] Comparative Example 12: NCM811 / / CC metal battery based on commercial carbon cloth anode (CC) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, a CC anode, a polypropylene-polyethylene composite porous film (PP-PE), and a polycrystalline 811 nickel cobalt manganese oxide (NCM811) cathode sheet (material mass ratio: NCM811 / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 13.53 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type NCM811 / / CC metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0081] (ii) Result analysis: Compared with Li and Cu negative electrodes, CC negative electrodes have a higher specific surface area, which can reduce the local current density on the electrode surface to a certain extent, reduce the nucleation overpotential of lithium deposition, and thus slow down the growth of lithium dendrites and the accumulation of failed lithium. Therefore, the stability of the assembled NCM811 / / CC metal battery at 0.5 C cycle is improved, and the discharge specific capacity and capacity retention rate after 300 cycles are 140.70 mAh g -1 and 73.58% (e.g. Fig. 9 ). However, due to the lack of lithium affinity on the CC surface and the function of regulating crystal growth orientation, its electrochemical performance as anode of metal batteries needs to be improved.

[0082] Comparative Example 13: NCM811 / / NCC metal battery based on nitrogen-doped modified carbon cloth anode (NCC) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, NCC anode, polypropylene-polyethylene composite porous film (PP-PE), and polycrystalline 811 nickel cobalt manganese oxide (NCM811) cathode (material mass ratio: NCM811 / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 13.53 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type NCM811 / / NCC metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0083] (ii) Result analysis: Compared with CC, NCC further reduces the local current density on the electrode surface and the nucleation overpotential of lithium deposition due to its reduced graphitization degree, increased interplanar spacing, reduced order, increased defectivity, and lithium affinity brought by nitrogen doping, thereby further slowing down the growth of lithium dendrites and the accumulation of failed lithium. Therefore, the stability of the assembled NCM811 / / NCC metal battery at 0.5 C cycling is further improved, and the discharge specific capacity and capacity retention rate after 300 cycles are 153.61 mAh g -1 and 78.86% (e.g. Fig. 9 ). However, since the NCC surface still lacks the function of regulating the crystal growth orientation, its electrochemical performance as anode of metal batteries still needs to be further improved.

[0084] Comparative Example 14: NCM811 / / LCC metal battery based on lanthanum-doped modified carbon cloth anode (LCC) (i) Under an inert gas atmosphere with a controlled moisture and oxygen content of < 1 ppm, an LCC anode, a polypropylene-polyethylene composite porous film (PP-PE), and a polycrystalline 811 nickel cobalt manganese oxide (NCM811) cathode sheet (material mass ratio: NCM811 / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 13.53 mg cm -2 )、1 mol L -1 LiPF 6 The electrolyte dissolved in EC / EMC / DMC (volume ratio 1:1:1) was packaged into LIR2025 button-type NCM811 / / LCC metal batteries. The assembled batteries were electrochemically tested under the same conditions.

[0085] (ii) Result analysis: Compared with CC, due to its reduced graphitization degree, increased interplanar spacing, reduced order, increased defectivity, and the crystal growth orientation regulation function brought by the doped lanthanum, LCC further reduces the local current density on the electrode surface and the nucleation overpotential of lithium deposition, thereby further slowing down the growth of lithium dendrites and the accumulation of failed lithium. Therefore, the stability of the assembled NCM811 / / LCC metal battery at 0.5 C cycling is further improved, and the discharge specific capacity and capacity retention rate after 300 cycles are 156.39 mAh g -1 and 81.66% (e.g. Fig. 9 ). However, due to the lack of lithium affinity on the surface of LCC, its electrochemical performance as anode of metal batteries still needs to be further improved.

[0086] Example 3: NCM811 / / NLCC metal battery based on nitrogen and lanthanum co-doped modified carbon cloth anode (NLCC) (i)Under the condition of an inert gas atmosphere with controlled moisture content and oxygen content < 1 ppm, an NLCC negative electrode, a polypropylene-polyethylene composite porous film (PP-PE), a polycrystalline nickel cobalt manganese oxide (NCM811) positive electrode sheet (mixing mass ratio: NCM811 / SP / KS6 / PVDF = 90 / 3 / 2 / 5, mass loading: 13.53 mg·cm -2 ), and an electrolyte in which 1 mol L -1 LiPF 6 is dissolved in EC / EMC / DMC (volume ratio 1:1:1) are encapsulated into an LIR2025 button-type NCM811 / / NLCC metal battery. The assembled battery is subjected to electrochemical tests under the same conditions.

[0087] (ii)Result analysis: Compared with NCC and LCC, due to its further reduced graphitization degree, increased crystal plane spacing, reduced order degree, increased defect degree, as well as the lithiophilicity brought by the co-doped nitrogen and the crystal growth orientation regulation function brought by the doped lanthanum, NLCC further reduces the local current density on the electrode surface and the nucleation overpotential of lithium deposition, thereby further slowing down the growth of lithium dendrites and the accumulation of dead lithium. Therefore, the stability of the assembled NCM811 / / NLCC metal battery during cycling at 0.5 C is further improved, and the discharge specific capacity and capacity retention rate after 300 cycles are 164.85 mAh g -1 and 85.26% (as shown in Fig. 9 ). Thus, combining the high specific surface area and high conductivity of the carbon material, the lithiophilicity brought by its doped nitrogen, and the crystal growth orientation regulation function brought by the doped lanthanum, nitrogen and lanthanum co-doped modified carbon cloth is proven to be usable as a multifunctional metal-free negative electrode to improve the electrochemical performance of metal batteries.

[0088] Example 4

[0089] A preparation method of a multifunctional metal-free negative electrode, comprising the following steps: Step 1, cleaning pretreatment of the carbon material: The carbon material is ultrasonically cleaned with dilute hydrochloric acid, acetone, and deionized water in sequence for 0.5 h and then dried; Step 2, acidification of the carbon material: The carbon material treated in Step 1 is treated with a mixed acid at 30 °C for 8 h, washed with deionized water until neutral, and then dried; The mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; Step 3, co-modification of the carbon material for metal affinity and crystal growth orientation regulation: The carbon material treated in Step 2 is added to a reaction medium containing both a metal affinity dopant and a crystal growth orientation regulator, and reacted at 100 °C for 48 h; The metal-philic dopant is a nitrogen dopant, and the amount used is 0.1 mol L -1 ; The crystal growth orientation regulator is lanthanum dopant, with an amount of 0.05 mol L -1 ; The reaction medium is a mixture of methanol and ethanol (volume ratio is 1:1); Step 4, cleaning and drying of the metal-affinity and crystal growth orientation regulated co-modified carbon material: take out the reacted carbon material, wash it with deionized water until it is neutral, and dry it to obtain the in-situ metal-affinity and crystal growth orientation regulated co-modified carbon material, which is a multifunctional metal-free negative electrode.

[0090] In step 1, the carbon material is carbon paper; In step 3, the nitrogen doping agent is a mixture of ammonia water and hydrazine hydrate (mass ratio is 1:1).

[0091] In step 3, the lanthanum dopant is lanthanum basic carbonate.

[0092] Example 5

[0093] A method for preparing a multifunctional metal-free negative electrode comprises the following steps: Step 1: Cleaning and pretreatment of carbon materials: ultrasonically clean the carbon materials with dilute hydrochloric acid, acetone, and deionized water for 2 hours and then dry them; Step 2, acidification of the carbon material: the carbon material treated in step 1 is treated with mixed acid at 80° C. for 1 h, washed with deionized water until neutral, and then dried; The mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; Step 3, co-modification of the metal-philic and crystal growth orientation-regulating carbon materials: adding the carbon material treated in step 2 to a reaction medium containing both a metal-philic dopant and a crystal growth orientation-regulating agent, and reacting at 200° C. for 6 hours; The metal-philic dopant is a nitrogen dopant, and the amount used is 10 mol L -1 ; The crystal growth orientation regulator is lanthanum dopant, with an amount of 10 mol L -1 ; The reaction medium is a mixture of ethylene glycol, N,N-dimethylformamide and N,N-dimethylacetamide (volume ratio is 1:1:1); Step 4, cleaning and drying of the metal-affinity and crystal growth orientation regulated co-modified carbon material: take out the reacted carbon material, wash it with deionized water until it is neutral, and dry it to obtain the in-situ metal-affinity and crystal growth orientation regulated co-modified carbon material, which is a multifunctional metal-free negative electrode.

[0094] In step 1, the carbon material is a mixture of carbon nanotubes, carbon nanofibers and graphite.

[0095] In step 3, the nitrogen dopant is a mixture of ethylenediamine, ammonium fluoroborate and ammonium phosphate (mass ratio is 1:1:1).

[0096] In step 3, the lanthanum dopant is a mixture of lanthanum fluoride and lanthanum nitrate (mass ratio is 1:1).

[0097] Example 6

[0098] A method for preparing a multifunctional metal-free negative electrode comprises the following steps: Step 1: Cleaning and pretreatment of carbon materials: ultrasonically clean the carbon materials with dilute hydrochloric acid, acetone, and deionized water for 1 hour and then dry them; Step 2, acidification of the carbon material: the carbon material treated in step 1 is treated with mixed acid at 50° C. for 4 h, washed with deionized water until neutral, and then dried; The mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; Step 3, co-modification of the metal-philic and crystal growth orientation regulation of the carbon material: adding the carbon material treated in step 2 to a reaction medium containing both a metal-philic dopant and a crystal growth orientation regulator, and reacting at 150° C. for 30 hours; The metal-philic dopant is a nitrogen dopant, and the amount used is 1 mol L -1 ; The crystal growth orientation regulator is lanthanum dopant, with an amount of 2 mol L -1 ; The reaction medium is ethanol; Step 4, cleaning and drying of the metal-affinity and crystal growth orientation regulated co-modified carbon material: take out the reacted carbon material, wash it with deionized water until it is neutral, and dry it to obtain the in-situ metal-affinity and crystal growth orientation regulated co-modified carbon material, which is a multifunctional metal-free negative electrode.

[0099] In step 1, the carbon material is a mixture of graphitized carbon and graphene (mass ratio is 1:1); In step 3, the nitrogen dopant is a mixture of ammonium hydrogen phosphate and ammonium dihydrogen phosphate (mass ratio is 1:1).

[0100] In step three, the lanthanum dopant is lanthanum chloride.

[0101] Example 7

[0102] A method for preparing a multifunctional metal-free negative electrode comprises the following steps: Step 1: Cleaning and pretreatment of carbon materials: ultrasonically clean the carbon materials with dilute hydrochloric acid, acetone, and deionized water for 1.2 h, 1.8 h, and 1.5 h, respectively, and then dry them; Step 2, acidification of the carbon material: the carbon material treated in step 1 is treated with mixed acid at 60° C. for 3 h, washed with deionized water until neutral, and then dried; The mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; Step 3: co-modification of the carbon material with metal affinity and crystal growth orientation regulation: adding the carbon material treated in step 2 to a reaction medium containing both a metal affinity dopant and a crystal growth orientation regulator, and reacting at 180° C. for 24 hours; The metal-philic dopant is a nitrogen dopant, and the amount used is 5 mol L -1 ; The crystal growth orientation regulator is lanthanum dopant, with an amount of 6 mol L -1 ; The reaction medium is N,N-dimethylformamide; Step 4, cleaning and drying of the metal-affinity and crystal growth orientation regulated co-modified carbon material: take out the reacted carbon material, wash it with deionized water until it is neutral, and dry it to obtain the in-situ metal-affinity and crystal growth orientation regulated co-modified carbon material, which is a multifunctional metal-free negative electrode.

[0103] In step 1, the carbon material is a mixture of carbon-based materials derived from carbon-containing substances (mass ratio is 1:1); The carbon-based material derived from the carbon-containing substance is a mixture of a covalent organic framework and a metal organic framework (mass ratio is 1:1); In step 3, the nitrogen doping agent is a mixture of urea, melamine and nitrogen-containing phenanthroline (mass ratio is 1:1:1).

[0104] In step 3, the lanthanum dopant is a mixture of lanthanum basic carbonate, lanthanum fluoride and lanthanum nitrate (mass ratio is 1:1:1).

[0105] Example 8

[0106] A method for preparing a multifunctional metal-free negative electrode comprises the following steps: Step 1: Cleaning and pretreatment of carbon materials: ultrasonically clean the carbon materials with dilute hydrochloric acid, acetone, and deionized water for 1.2 hours and then dry them; Step 2, acidification of the carbon material: the carbon material treated in step 1 is treated with mixed acid at 45° C. for 6 h, washed with deionized water until neutral, and then dried; The mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; Step 3: co-modification of the carbon material with metal affinity and crystal growth orientation regulation: adding the carbon material treated in step 2 to a reaction medium containing both a metal affinity dopant and a crystal growth orientation regulator, and reacting at 120° C. for 42 hours; The metal-philic dopant is a nitrogen dopant, and the amount used is 8 mol L -1 ; The crystal growth orientation regulator is lanthanum dopant, with an amount of 3 mol L -1 ; The reaction medium is N,N-dimethylacetamide; Step 4, cleaning and drying of the metal-affinity and crystal growth orientation regulated co-modified carbon material: take out the reacted carbon material, wash it with deionized water until it is neutral, and dry it to obtain the in-situ metal-affinity and crystal growth orientation regulated co-modified carbon material, which is a multifunctional metal-free negative electrode.

[0107] In step 1, the carbon material is a mixture of two-dimensional transition metal carbide and biomass (mass ratio is 1:1).

[0108] In step three, the nitrogen doping agent is ammonia water.

[0109] In step 3, the lanthanum dopant is lanthanum basic carbonate.

[0110] Example 9

[0111] A metal battery comprising the multifunctional metal-free negative electrode described in the fourth embodiment.

[0112] The metal battery is a sodium metal battery.

[0113] It includes a shell, a positive electrode, a negative electrode and a diaphragm installed in the shell; the diaphragm is arranged between the positive electrode and the negative electrode; the gap between the positive electrode and the diaphragm, and the gap between the negative electrode and the diaphragm are filled with electrolyte; the negative electrode adopts the multifunctional metal-free negative electrode described in the above embodiment 4.

[0114] The separator is a polypropylene porous membrane.

[0115] Example 10

[0116] A metal battery comprising the multifunctional metal-free negative electrode described in the above embodiment 5.

[0117] The metal battery is a potassium metal battery.

[0118] It includes a shell, a positive electrode, a negative electrode and a diaphragm installed in the shell; the diaphragm is arranged between the positive electrode and the negative electrode; the gap between the positive electrode and the diaphragm, and the gap between the negative electrode and the diaphragm are filled with electrolyte; the negative electrode adopts the multifunctional metal-free negative electrode described in the above embodiment 5.

[0119] The separator is a cellulose porous membrane.

[0120] Embodiment 11

[0121] A metal battery comprising the multifunctional metal-free negative electrode described in Example 6 above.

[0122] The metal battery is a magnesium metal battery.

[0123] It includes a shell, a positive electrode, a negative electrode and a diaphragm installed in the shell; the diaphragm is arranged between the positive electrode and the negative electrode; the gap between the positive electrode and the diaphragm, and the gap between the negative electrode and the diaphragm are filled with electrolyte; the negative electrode adopts the multifunctional metal-free negative electrode described in the above embodiment 6.

[0124] The diaphragm is ceramic.

[0125] Example 12

[0126] A metal battery comprising the multifunctional metal-free negative electrode described in the above-mentioned embodiment 7.

[0127] The metal battery is a zinc metal battery.

[0128] It includes a shell, a positive electrode, a negative electrode and a diaphragm installed in the shell; the diaphragm is arranged between the positive electrode and the negative electrode; the gap between the positive electrode and the diaphragm, and the gap between the negative electrode and the diaphragm are filled with electrolyte; the negative electrode adopts the multifunctional metal-free negative electrode described in the above embodiment 7.

[0129] The diaphragm is nylon.

[0130] Example 13

[0131] A metal battery comprising the multifunctional metal-free negative electrode described in Example 8 above.

[0132] The metal battery is an aluminum metal battery.

[0133] It includes a shell, a positive electrode, a negative electrode and a diaphragm installed in the shell; the diaphragm is arranged between the positive electrode and the negative electrode; the gap between the positive electrode and the diaphragm, and the gap between the negative electrode and the diaphragm are filled with electrolyte; the negative electrode adopts the multifunctional metal-free negative electrode described in the above embodiment 8.

[0134] The diaphragm is asbestos paper.

[0135] Embodiment 14

[0136] A metal battery comprises the multifunctional metal-free negative electrode described in the above embodiment 1.

[0137] The metal battery is a lithium metal battery.

[0138] It includes a shell, a positive electrode, a negative electrode and a diaphragm installed in the shell; the diaphragm is arranged between the positive electrode and the negative electrode; the gap between the positive electrode and the diaphragm, and the gap between the negative electrode and the diaphragm are filled with electrolyte; the negative electrode adopts the multifunctional metal-free negative electrode described in the above embodiment 1.

[0139] The separator is a polyimide membrane.

[0140] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a multifunctional metal-free negative electrode, characterized in that: The steps include: Step 1: Cleaning and pretreatment of carbon materials: ultrasonically clean the carbon materials with dilute hydrochloric acid, acetone, and deionized water for 0.5 to 2 hours and then dry them; Step 2, acidification of the carbon material: the carbon material treated in step 1 is treated with mixed acid at 30-80° C. for 1-6 hours, washed with deionized water until neutral, and then dried; The mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, wherein the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; Step 3, co-modification of the metal-philic and crystal growth orientation regulation of the carbon material: adding the carbon material treated in step 2 to a reaction medium containing both a metal-philic dopant and a crystal growth orientation regulator, and reacting at 100 to 200° C. for 6 to 48 hours; The metal-philic dopant is a nitrogen dopant, and the amount used is 0.1 to 10 mol L -1 ; The crystal growth orientation regulator is lanthanum dopant, and the dosage is 0.05~10 mol L -1 ; The reaction medium is at least one of deionized water, methanol, ethanol, ethylene glycol, N,N-dimethylformamide, and N,N-dimethylacetamide; Step 4, cleaning and drying of the metal-affinity and crystal growth orientation regulated co-modified carbon material: take out the reacted carbon material, wash it with deionized water until it is neutral, and dry it to obtain the in-situ metal-affinity and crystal growth orientation regulated co-modified carbon material, which is a multifunctional metal-free negative electrode.

2. The method for preparing a multifunctional metal-free negative electrode according to claim 1, characterized in that: In step 1, the carbon material is at least one of carbon paper, carbon cloth, carbon nanotubes, carbon nanofibers, graphite, graphitized carbon, graphene, and carbon-based materials derived from carbon-containing substances; The carbon-based materials derived from carbon-containing substances include covalent organic frameworks, metal organic frameworks, two-dimensional transition metal carbides and biomass.

3. The method for preparing a multifunctional metal-free negative electrode according to claim 1, characterized in that: In step three, the nitrogen doping agent is at least one of urea, ammonia water, hydrazine hydrate, ethylenediamine, ammonium fluoroborate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, melamine, and nitrogen-containing phenanthroline.

4. The method for preparing a multifunctional metal-free negative electrode according to claim 1, characterized in that: In step three, the lanthanum dopant is at least one of lanthanum chloride, lanthanum basic carbonate, lanthanum fluoride and lanthanum nitrate.

5. A multifunctional metal-free negative electrode prepared by the method for preparing a multifunctional metal-free negative electrode according to any one of claims 1 to 4.

6. A metal battery, characterized in that: Contains the multifunctional metal-free negative electrode according to any one of claims 1 to 4.

7. The metal battery according to claim 6, characterized in that: The metal battery is a lithium, sodium, potassium, magnesium, zinc or aluminum metal battery.

8. The metal battery according to claim 6, characterized in that: It comprises a shell, a positive electrode, a negative electrode and a diaphragm installed in the shell; the diaphragm is arranged between the positive electrode and the negative electrode; the gap between the positive electrode and the diaphragm, and the gap between the negative electrode and the diaphragm are filled with electrolyte; the negative electrode adopts the multifunctional metal-free negative electrode described in any one of claims 1 to 4.

9. The metal battery according to claim 8, characterized in that: The separator is a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene-polyethylene composite porous membrane, a cellulose porous membrane, a glass fiber porous membrane, a polyester membrane, a polyimide membrane, a polyamide membrane, ceramics, nylon or asbestos paper.

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