A lithium-philic substrate material for a lithium metal negative electrode and its preparation method and application

Abstract

The present invention discloses a lithium metal negative electrode lithium-philic substrate material and its preparation method and application; the present invention obtains a metal salt aqueous solution 1 by dissolving nickel salt and zinc salt in deionized water; adds hexadecyltrimethylammonium bromide to the metal salt aqueous solution 1 and stirs to obtain a solution 2; adds urea to the solution 2 and stirs to obtain a solution 3; performs a hydrothermal reaction on the solution 3 to obtain a precursor mixture; filters, washes and dries the precursor mixture to obtain a precursor powder; and sinters the precursor powder in an ammonia atmosphere to obtain a lithium-philic material. The lithium-philic material described in the present invention has the advantages of simple preparation method, convenient control, large output, and easy industrialization. The lithium-philic material with high chemical stability, high conductivity and low cost prepared by the present invention shows good performance in the application of lithium metal batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium metal battery negative electrode preparation, and specifically relates to a lithium metal negative electrode lithium-philic base material and a preparation method and application thereof. Background Art

[0002] With the continuous development of green energy, human beings' demand for high energy density of energy storage devices is also growing. Efficient and stable green energy storage and conversion is the driving force for the sustainable development of future science and technology. The emergence of batteries can help us use energy more efficiently and conveniently. Since the last century, various forms of batteries have been commercially applied, such as lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries and lithium-ion batteries. The successful commercial application of lithium-ion batteries has changed people's lifestyles and promoted the rapid development of portable cameras, mobile phones, laptops and electric vehicles.

[0003] However, despite the rapid development of lithium-ion batteries, their energy density has increased slowly. In the past 150 years, the energy density of batteries has only increased from 40Wh·kg of lead-acid batteries to 1.5W·kg. -1 Increase to 200Wh·kg of current lithium-ion batteries -1 This growth rate is far from meeting people's demand for energy. As the actual energy density of graphite anode in lithium-ion batteries gradually approaches its theoretical limit, we urgently need more efficient electrode materials to meet the needs of the development of emerging high-end energy storage devices.

[0004] Lithium metal anode has a very high theoretical capacity (3860 mAh g -1 ) and the lowest (negative) potential (-3.04V vs standard hydrogen electrode) and is widely considered to be the most promising negative electrode material for the next generation of lithium-ion batteries, and has attracted great attention from researchers. At present, the batteries that can use metallic lithium as the negative electrode mainly include: lithium-sulfur batteries, lithium-air batteries, lithium-oxide batteries and lithium-ion batteries. These new batteries have shown high theoretical energy density (lithium-air battery: 3500Wh·kg -1 , Lithium-sulfur battery: 2600Wh·kg -1 , Lithium-oxide battery: 1000-1500Wh·kg -1. Therefore, lithium metal batteries with lithium metal as the negative electrode are likely to become the next generation of energy storage batteries. However, these lithium metal batteries have serious safety issues (lithium dendrite growth causes battery short circuit) and are difficult to cycle stably (low coulomb efficiency). Lithium dendrite growth can cause battery short circuit, which may cause thermal runaway, posing the risk of fire or even explosion. This problem directly leads to the inability of lithium metal secondary batteries to be commercially applied. Since the commercial application of lithium-ion batteries, most lithium metal battery products have been abandoned by the market. However, as a negative electrode material with extremely high energy density, researchers have never stopped exploring metallic lithium. In recent years, people have developed a variety of emerging strategies to inhibit the growth of lithium dendrites at lithium metal negative electrodes, thereby improving the safety and service life of batteries, in anticipation of their ultimate practical application.

[0005] Using lithiophilic materials as current collectors for lithium metal anodes is a very effective method that can effectively reduce the overpotential during lithium deposition and ensure uniform deposition of lithium metal, thereby greatly reducing the possibility of battery short circuit caused by the formation of lithium dendrites. (Huang, K.; Li, Z.; Xu, Q.; Liu, H.; Li, H.; Wang, Y., Lithiophilic CuO Nanoflowers on Ti-Mesh Inducing Lithium Lateral Plating Enabling Stable Lithium-Metal Anodes with Ultrahigh Rates and Ultralong Cycle Life. ADVANCEDENERGY MATERIALS 2019, 9 (29).) Currently reported lithiophilic materials mainly include pure metal lithiophilic materials, lithiophilic alloy materials, metal oxide lithiophilic materials, and metal nitride lithiophilic materials. Since most pure metal or metal alloy lithiophilic materials are mainly composed of gold and silver, their prices are relatively high, and large-scale commercial applications will increase the cost of battery production. However, metal oxide and nitride lithium-philic materials have low electronic conductivity and will undergo irreversible side reactions with metallic lithium. Therefore, the interface transport layer materials of metallic lithium negative electrodes need more in-depth research. Summary of the invention

[0006] In order to overcome the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method for preparing a lithium-philic material with high chemical stability, high electrical conductivity and low cost, aiming to improve the lithium-philicity of the base material while ensuring high electrical conductivity and high chemical stability of metallic lithium, and effectively ensure uniform deposition of metallic lithium and inhibit the formation of metallic lithium dendrites.

[0007] The purpose of the present invention is achieved by at least one of the following technical solutions.

[0008] A method for preparing a lithium metal negative electrode lithium-philic substrate material comprises the following steps:

[0009] (1) dissolving nickel salt and zinc salt in deionized water to obtain a metal salt aqueous solution 1;

[0010] (2) adding hexadecyltrimethylammonium bromide to the metal salt aqueous solution 1 in step (1), stirring the mixture, and obtaining a solution 2;

[0011] (3) adding urea to the solution 2 described in step (2), stirring to obtain a solution 3;

[0012] (4) subjecting the solution 3 of step (3) to a hydrothermal reaction to obtain a precursor mixture;

[0013] (5) filtering, washing, and drying the precursor mixture of step (4) to obtain a precursor powder;

[0014] (6) Sintering the precursor powder described in step (5) in an ammonia atmosphere to obtain a lithium-philic material.

[0015] Preferably, the molar ratio of the nickel salt to the zinc salt in step (1) is (1:1)-(5:1);

[0016] Further preferably, the molar ratio of the nickel salt to the zinc salt in step (1) is 3:1;

[0017] Preferably, the nickel salt in step (1) is Ni(NO3)2·6H2O, and the zinc salt is Zn(NO3)2·6H2O.

[0018] Preferably, the total mass percentage concentration of nickel salt and zinc salt in the metal salt aqueous solution 1 in step (1) is 5-30%;

[0019] Further preferably, the total mass percentage concentration of nickel salt and zinc salt in the metal salt aqueous solution 1 in step (1) is 10%;

[0020] Preferably, the stirring time in step (1) is 10-30 min.

[0021] Further preferably, the stirring time in step (1) is 15 minutes.

[0022] Preferably, the molar ratio of the hexadecyltrimethylammonium bromide in step (2) to the total amount of the nickel salt and the zinc salt in step (1) is (1:5)-(1:10);

[0023] Further preferably, the molar ratio of the hexadecyltrimethylammonium bromide in step (2) to the total amount of the nickel salt and the zinc salt in step (1) is 1:7;

[0024] Preferably, the stirring time in step (2) is 60-180 min;

[0025] Further preferably, the stirring time in step (2) is 120 min;

[0026] Preferably, the stirring temperature in step (2) is 40-90°C.

[0027] More preferably, the stirring temperature in step (2) is 60°C.

[0028] Preferably, the molar ratio of urea to the total amount of nickel salt and zinc salt in step (3) is (5:1)-(10:1);

[0029] Further preferably, the molar ratio of the urea to the total amount of the nickel salt and the zinc salt in step (3) is 1:1;

[0030] Preferably, the stirring time in step (3) is 30-60 min.

[0031] Further preferably, the stirring time in step (3) is 30 minutes.

[0032] Preferably, the temperature of the hydrothermal reaction in step (4) is 80-140° C. and the time is 3-16 h.

[0033] Further preferably, the temperature of the hydrothermal reaction in step (4) is 120° C. and the time is 8 hours.

[0034] Preferably, the washing in step (5) is performed by alternating washing with ethanol and deionized water;

[0035] Preferably, the drying process in step (5) is vacuum drying at a temperature of 40-80°C for a time of 6-24 hours.

[0036] More preferably, the temperature is 60° C. and the time is 12 h.

[0037] Preferably, the sintering temperature in step (6) is 300-800°C;

[0038] Further preferably, the sintering temperature in step (6) is 450° C.

[0039] Preferably, the sintering time in step (6) is 2-8 hours;

[0040] Further preferably, the sintering time in step (6) is 4 hours;

[0041] Preferably, the ammonia flow rate of the ammonia atmosphere in step (6) is 0.1-1 L / h.

[0042] The lithium metal negative electrode lithiophilic base material prepared by the above preparation method.

[0043] The above-mentioned lithium metal negative electrode lithiophilic base material is used in the preparation of lithium metal negative electrode current collector material and lithium metal negative electrode current collector interface material.

[0044] Based on the lithium-philic principle of lithium-philic materials and the chemical stability of materials with metallic lithium, the present invention utilizes antiperovskite nitrides containing nitrogen (N), nickel (Ni), and zinc (Zn) as lithium-philic materials for metallic lithium negative electrode current collectors for the first time, and prepares a series of lithium-philic metallic lithium negative electrode current collectors.

[0045] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0046] The present invention prepares a lithium-philic interface material / lithium-philic substrate material with high chemical stability and high conductivity, which can effectively ensure the uniform deposition of metal lithium and inhibit the formation of metal lithium dendrites. The method is easy to synthesize and has good repeatability. The obtained electrode material or modified electrode can be directly used as a metal lithium battery with no dendrites and high coulombic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is the X-ray powder diffraction characterization result curve of ZnNNi3 prepared in Example 1;

[0048] Figure 2 A schematic diagram of the chemical structure of ZnNNi3 prepared in Example 1;

[0049] Figure 3 The nucleation overpotential and polarization overpotential curves of ZnNNi3 prepared in Example 1 during the lithium deposition process;

[0050] Figure 4 This is the lithium-to-lithium long cycle test curve of ZnNNi3 prepared in Example 1, 1.0 mA / cm 2 ,1.0mA h / cm 2 ;

[0051] Figure 5 This is the X-ray powder diffraction characterization result curve of ZnNNi3 prepared in Example 2;

[0052] Figure 6 The cycle test curve of the metal lithium negative electrode prepared in Example 2 and lithium iron phosphate at a current density of 1C;

[0053] Figure 7 This is the lithium-to-lithium long cycle test curve of ZnNNi3 prepared in Example 3, 1.0 mA / cm 2 ,1.0mA h / cm 2 ;

[0054] Figure 8 The graph is a cycle test result of the metal lithium negative electrode prepared in Example 3 and matched with NMC (111) at a current density of 1C;

[0055] Fig. 9 This is the full-cell rate test curve of NCM (111) prepared in Example 3 (the current densities in the figure are 0.2C, 0.5C, 1.0C, 2.0C, 5.0C, 10.0C, 5.0C, 2.0C, 1.0C, 0.5C, 0.2C, and 1.0C, respectively);

[0056] Fig.10 This is a graph showing the CV stability test results of the pure ZnNNi3 electrode prepared in Example 4 for metallic lithium;

[0057] Fig.11 This is a graph showing the electronic conductivity test results of the ZnNNi3 lithium-philic material and Ketjen black prepared in Example 4. DETAILED DESCRIPTION

[0058] The specific implementation of the present invention is further described below in conjunction with examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that if there are processes that are not particularly described in detail below, they can be implemented or understood by those skilled in the art with reference to the prior art. If the manufacturer of the reagents or instruments used is not indicated, they are deemed to be conventional products that can be purchased commercially.

[0059] Example 1

[0060] Weigh 7.5mmol of Ni(NO3)2·6H2O powder and 2.5mmol of Zn(NO3)2·6H2O powder and dissolve them in 100mL of deionized water. Stir at room temperature for 15min until the two metal nitrates are completely dissolved, then add 1.4mmol of CTAB powder and continue stirring at 60℃ for 2h until the reaction is complete and a clear solution is formed. Then add 10mmol of urea to the above solution and continue stirring for 1h. After stirring evenly, transfer to a stainless steel reactor with a polytetrafluoroethylene substrate for hydrothermal treatment at 110℃ for 12h. After the treatment is completed, the obtained slurry is filtered, washed (anhydrous ethanol, deionized water), and dried (vacuum oven 60℃, 12h). Then the obtained precursor powder is placed in a tubular furnace containing an ammonia atmosphere (flow rate 25L / h) for sintering at 450℃ for 4h. Finally, the lithium-philic interface material / lithium-philic substrate material with high chemical stability and high conductivity is obtained. The above-mentioned lithium-philic material is evenly coated on the surface of the carbon cloth, and then loaded into a battery containing metal lithium for lithium deposition. Then two pieces of carbon cloth / ZnNNi3 pole pieces after lithium deposition are assembled again into a "lithium-to-lithium" symmetrical battery for stability testing (pure carbon cloth without lithium-philic material coating is used as a comparative example).

[0061] like Figure 1 , XRD powder diffraction characterization shows that the material can completely correspond to the simulated diffraction peak position, and the ordered peak at a low angle can also indicate that the material has a structure with orderly atomic arrangement; Figure 2 is a schematic diagram of the chemical structure of the material; Figure 3 are the nucleation overpotential and polarization overpotential during lithium deposition; Figure 4 The results of the lithium-to-lithium long cycle test. Compared with the pure carbon cloth electrode, the electrode modified with ZnNNi3 showed obvious stability advantages in the lithium-to-lithium test. The uniform deposition of lithium metal can effectively reduce the side reactions of metallic lithium and improve the utilization efficiency of metallic lithium.

[0062] Example 2

[0063] Weigh 7.5mmol of Ni(NO3)2·6H2O powder and 2.5mmol of Zn(NO3)2·6H2O powder and dissolve them in 100mL of deionized water. Stir at room temperature for 15min until the two metal nitrates are completely dissolved, then add 1.4mmol of CTAB powder and continue stirring at 60℃ for 2h until the reaction is complete and a clear solution is formed. Then add 10mmol of urea to the above solution and continue stirring for 1h. After stirring evenly, transfer to a stainless steel reactor with a polytetrafluoroethylene substrate for hydrothermal treatment at 120℃ for 12h. After the treatment is completed, the obtained slurry is filtered, washed (anhydrous ethanol, deionized water), and dried (vacuum oven 60℃, 12h). Then the obtained precursor powder is placed in a tubular furnace containing an ammonia atmosphere (flow rate 25L / h) for sintering at 500℃ for 4h. Finally, the lithium-philic interface material / lithium-philic substrate material with high chemical stability and high conductivity is obtained. The above-mentioned lithium-philic material is evenly coated on the surface of the carbon cloth, and then loaded into a battery containing metallic lithium for lithium deposition. The carbon cloth / ZnNNi3 electrode after lithium deposition is then assembled with a lithium iron phosphate electrode to form a full battery for cycle life testing (pure carbon cloth without lithium-philic material coating is used as a comparative example).

[0064] like Figure 5 , X-ray powder diffraction test results of materials; Figure 6 The results of the full-battery cycle test of lithium iron phosphate. Compared with the pure carbon cloth electrode, the electrode modified with ZnNNi3 showed obvious stability advantages in the full-battery test of lithium iron phosphate. The uniform deposition of lithium metal can effectively reduce the side reactions of metal lithium and improve the utilization efficiency of metal lithium.

[0065] Example 3

[0066] Weigh 7.5mmol of Ni(NO3)2·6H2O powder and 2.5mmol of Zn(NO3)2·6H2O and dissolve them in 100mL of deionized water. Stir at room temperature for 15min until the two metal nitrates are completely dissolved, then add 1.2mmol of CTAB powder and continue stirring at 60℃ for 2h until the reaction is complete and a clear solution is formed. Then add 8mmol of urea to the above solution and continue stirring for 1h. After stirring evenly, transfer to a stainless steel reactor with a polytetrafluoroethylene substrate for hydrothermal treatment at 110℃ for 12h. After the treatment is completed, the obtained slurry is filtered, washed (anhydrous ethanol, deionized water), and dried (vacuum oven 60℃, 12h). Then the obtained precursor powder is placed in a tubular furnace containing an ammonia atmosphere (flow rate 25L / h) for sintering at 400℃ for 4h. Finally, the lithium-philic interface material / lithium-philic substrate material with high chemical stability and high conductivity is obtained. The above-mentioned lithium-philic material is evenly coated on the surface of the carbon cloth, and then loaded into a battery containing metallic lithium for lithium deposition. The carbon cloth / ZnNNi3 electrode after lithium deposition is then assembled with the ternary positive electrode NCM (111) electrode to form a full battery for cycle life testing (pure carbon cloth without lithium-philic material coating is used as a comparative example).

[0067] like Figure 7 , the lithium-to-lithium long cycle test results of the material; Figure 8 These are the NMC (111) full battery cycle test results. Fig. 9 The results of the NCM (111) full battery rate test. Compared with the pure carbon cloth electrode, the electrode modified with ZnNNi3 showed obvious stability advantages in the NMC (111) full battery test. The uniform deposition of lithium metal can effectively reduce the side reactions of metallic lithium and improve the utilization efficiency of metallic lithium.

[0068] Example 4

[0069] Weigh 7.5mmol of Ni(NO3)2·6H2O powder and 2.5mmol of Zn(NO3)2·6H2O powder and dissolve them in 100mL of deionized water. Stir at room temperature for 15min until the two metal nitrates are completely dissolved, then add 1.2mmol of CTAB powder and continue stirring at 60℃ for 2h until the reaction is complete and a clear solution is formed. Then add 8mmol of urea to the above solution and continue stirring for 1h. After stirring evenly, transfer to a stainless steel reactor with a polytetrafluoroethylene substrate for hydrothermal treatment at 110℃ for 12h. After the treatment is completed, the obtained slurry is filtered, washed (anhydrous ethanol, deionized water), and dried (vacuum oven 60℃, 12h). Then the obtained precursor powder is placed in a tubular furnace containing an ammonia atmosphere (flow rate 25L / h) for sintering at 450℃ for 4h. Finally, the lithium-philic interface material / lithium-philic substrate material with high chemical stability and high conductivity is obtained. The above-mentioned lithium-philic material is uniformly coated on the surface of the copper foil, and then loaded into a battery containing metallic lithium for LSV testing to analyze the chemical stability of the lithium-philic material to metallic lithium or lithium ions.

[0070] Fig.10 The CV cycle test results show that the lithium-philic material does not have any irreversible side reactions during the conversion of lithium ions and metallic lithium, indicating that the material has good chemical stability to metallic lithium / lithium ions.

[0071] Fig.11 The electron conductivity test results are shown in Figure 2. The lithium-philic material has good electron conductivity.

[0072] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement modes and shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a lithium metal negative electrode lithiophilic substrate material, characterized in that: The steps include: (1) dissolving nickel salt and zinc salt in deionized water, and stirring to obtain a metal salt aqueous solution 1; (2) adding hexadecyltrimethylammonium bromide to the metal salt aqueous solution 1 in step (1), stirring the mixture, and obtaining a solution 2; (3) adding urea to the solution 2 described in step (2), stirring to obtain a solution 3; The molar ratio of the urea to the total amount of the nickel salt and the zinc salt is (5:1)-(10:1); (4) subjecting the solution 3 of step (3) to a hydrothermal reaction to obtain a precursor mixture; the temperature of the hydrothermal reaction is 110-140° C.; the time of the hydrothermal reaction is 3-16 h; (5) filtering, washing, and drying the precursor mixture in step (4) to obtain a precursor powder; (6) Sintering the precursor powder in step (5) in an ammonia atmosphere to obtain a lithium-philic substrate material ZnNNi3; the sintering temperature is 300-800°C; and the sintering time is 2-8h.

2. The method for preparing the lithium metal negative electrode lithiophilic substrate material according to claim 1, characterized in that: The molar ratio of the nickel salt to the zinc salt in step (1) is (1:1)-(5:1); The nickel salt is Ni(NO3)2·6H2O, and the zinc salt is Zn(NO3)2·6H2O.

3. The method for preparing the lithium metal negative electrode lithiophilic substrate material according to claim 1, characterized in that: The total mass percentage concentration of nickel salt and zinc salt in the metal salt aqueous solution 1 of step (1) is 5-30%; The stirring time in step (1) is 10-30 minutes.

4. The method for preparing the lithium metal negative electrode lithiophilic substrate material according to claim 1, characterized in that: The molar ratio of the hexadecyltrimethylammonium bromide in step (2) to the total amount of the nickel salt and the zinc salt in step (1) is (1:5)-(1:10); The stirring time in step (2) is 60-180 minutes; The stirring temperature in step (2) is 40-90°C.

5. The method for preparing the lithium metal negative electrode lithiophilic substrate material according to claim 1, characterized in that: The stirring time in step (3) is 30-60 minutes.

6. The method for preparing the lithium metal negative electrode lithiophilic substrate material according to claim 1, characterized in that: The washing in step (5) is performed by alternating washing with ethanol and deionized water; The drying process in step (5) is vacuum drying at a temperature of 40°C-80°C and a time of 6-24 hours.

7. The method for preparing the lithium metal negative electrode lithiophilic substrate material according to claim 1, characterized in that: The ammonia flow rate of the ammonia atmosphere in step (6) is 0.1-1 L / h.

8. A lithium-metal negative electrode lithiophilic substrate material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the lithium metal negative electrode lithiophilic substrate material according to claim 8 in the preparation of lithium metal negative electrode current collector materials and lithium metal negative electrode current collector interface materials.

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