A method for preparing large-area single-crystal lithium metal and a metal lithium battery

Abstract

The present invention belongs to the technical field of inorganic material preparation and energy material, and specifically relates to a method for preparing large-area single-crystal lithium metal and a metal lithium battery. The method places lithium metal foil in a halooctane solution by chemical impregnation for surface modification, generates a uniformly dispersed lithium halide surface layer on the surface of the lithium metal, and guides the large-area single crystal growth of molten lithium metal in the subsequent heat treatment process, and finally puts it into an electrolyte to dissolve the lithium halide layer on the surface to obtain a large-area single-crystal metal lithium foil. The present invention improves the transmission dynamics of lithium ions on the electrode surface and in the bulk phase by regulating the crystal structure, thereby uniformly depositing lithium and improving the cycle stability of lithium metal batteries; large-area single-crystal lithium foil can not only be used for the assembly of button batteries, but can also be directly applied to the assembly of large-capacity soft-pack batteries, providing new possibilities for the design of high-energy-density energy storage devices.

Description

Technical Field

[0001] This invention belongs to the field of inorganic material preparation and energy material technology, specifically relating to a method for preparing large-area single-crystal lithium metal and a lithium metal battery. Background Technology

[0002] With the increasing severity of the energy crisis and environmental pollution, the global demand for clean energy and efficient energy storage technologies continues to grow. Among various energy storage technologies, batteries have become an important development direction. Although traditional lithium-ion batteries have achieved significant success in practical applications, the theoretical energy storage capacity of their anode materials has reached its limit, making it increasingly difficult to further increase their energy density. Therefore, under this technological bottleneck, lithium metal batteries, due to their high energy density (3860 mAh g / g), have become a leading technology. -1 It is highly favored and regarded as one of the important candidates for the next generation of breakthrough high-energy batteries.

[0003] However, as a crucial component of lithium metal batteries, lithium metal anodes face significant safety and stability challenges in practical applications due to their unique physicochemical properties (such as ultra-high theoretical specific capacity, low melting point, and high reactivity). Currently, researchers have attempted to address the issues of lithium metal in battery cycling through methods such as interface modification, three-dimensional composite anodes, electrolyte additives, and the development of solid-state electrolytes. However, most of these strategies focus on modifying the lithium metal anode or electrolyte, without addressing the fundamental and original preparation of the lithium metal anode itself.

[0004] In fact, traditional lithium metal usually contains a variety of impurities and crystal defects, typically containing multiple crystal planes such as (110), (200), and (211). The transport dynamics and other properties of each crystal plane are different, resulting in uneven lithium deposition in subsequent processes. This leads to tip deposition during charging and discharging, causing problems such as dendrite growth and internal short circuits. Moreover, existing lithium metal preparation methods, such as electrolysis and zone melting, have many limitations in achieving large-area, continuous, and single-crystallization. For example, it is difficult to control the crystal morphology and cannot guarantee consistency and crystal integrity over a large area. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing large-area single-crystal lithium metal, which can eliminate irregular grain boundaries of lithium metal anodes, reduce grain boundary resistance, and improve ion transport dynamics on the anode surface.

[0006] The specific technical solution adopted by this invention is as follows:

[0007] A method for preparing large-area single-crystal lithium metal, the method comprising the following steps:

[0008] S1: The lithium metal foil is placed in a halooctane solution for surface modification by chemical impregnation.

[0009] S2: A uniformly dispersed lithium halide surface layer is generated on the lithium metal surface, and the large-area single crystal growth of molten lithium metal is guided during the subsequent heat treatment process;

[0010] S3: Lithium metal is placed in an electrolyte to dissolve the lithium halide layer on the surface, resulting in a large-area single-crystal lithium foil.

[0011] In S1, the lithium metal foil has a purity of 98wt% or higher, a thickness of 50μm to 500μm, a width of 1cm to 10cm, and a length of 5cm to 25cm.

[0012] In step S1, the lithium metal foil is wound in multiple turns during the processing to increase the processing area of ​​the lithium metal foil.

[0013] In S1, the halooctane is C8H. 17 F, C8H 17 Cl, C8H 17 Br, C8H 17 I is any one or more of the following, wherein the solvent is tetrahydrofuran.

[0014] In the halooctane solution, the mass ratio of halooctane solute to organic solvent is 1:30 to 1:100.

[0015] The halooctane solution needs to be magnetically stirred for 1 to 10 hours beforehand to generate a uniform lithium halide surface layer on the lithium metal surface.

[0016] In S1, the surface modification treatment method is as follows: the lithium metal foil is fully immersed in a halooctane solution for 1h to 10h, and then taken out and dried at room temperature for 1h to 12h.

[0017] The specific method of heat treatment in S2 is as follows: starting from room temperature, the temperature is increased at a rate of 1℃ / min to 10℃ / min, and then held at 181℃ to 300℃ for 1 to 300 minutes, and finally naturally cooled to room temperature.

[0018] The electrolyte in S3 includes any one of the following: 1M LiTFSI in DOL / DME with 2% LiNO3, 0.2M LiPF6, 0.2M LiBF4, 0.8M LiDFOB in DEC:FEC = 2:1 Vol%, 1M LiTFSI in DME:DOL = 1:1 Vol%, and 1M LiPF6 in EC:DEC = 1:1 Vol%.

[0019] A lithium metal battery is obtained by the above-described preparation method.

[0020] The technical effects achieved by this invention are as follows:

[0021] The method for preparing large-area single-crystal lithium metal according to the present invention helps to eliminate irregular grain boundaries commonly found in polycrystalline structures. These boundaries are often a major cause of lithium dendrite growth, "dead lithium" formation, and internal short circuits in batteries. By realizing a single-crystal lithium metal structure, the safety hazards caused by dendrites can be significantly reduced.

[0022] The method for preparing large-area monocrystalline lithium metal according to the present invention provides a large-area monocrystalline lithium with lower grain boundary resistance compared to polycrystalline lithium. Therefore, it can effectively reduce the interfacial impedance between the electrolyte and the electrode, further optimize the battery charging and discharging efficiency, and extend the battery life.

[0023] The method for preparing large-area single-crystal lithium metal according to the present invention provides a method for preparing large-area single-crystal lithium metal. When the large-area single-crystal lithium metal is used as an electrode material, its uniform crystal structure greatly improves the transport dynamics of lithium ions on the electrode surface and in the bulk phase, thereby achieving uniform lithium deposition and improving the cycle stability of the battery. Attached Figure Description

[0024] Figure 1 These are the XRD patterns of metallic lithium prepared in Example 1 and Comparative Example 1 of this invention;

[0025] Figure 2 The symmetrical battery of Embodiment 1 and Comparative Example 1 of this invention is at 1 mA cm -2 -10mAh cm -2 SEM image of the deposition morphology on the electrode surface after conditional electrodeposition;

[0026] The electrolyte is 1M LiPF6 in EC:DEC = 1:1 Vol%.

[0027] Figure 3 The symmetrical cells of Embodiment 1 and Comparative Example 1 of this invention are at 1 mA cm -2 -1mAh cm -2 EIS impedance spectrum of the battery after 100 cycles under the specified conditions;

[0028] The electrolyte is 1M LiPF6 in EC:DEC = 1:1 Vol%.

[0029] Figure 4 The symmetrical battery of Embodiment 1 and Comparative Example 1 of this invention is at 1 mA cm -2 -1mAh cm -2 Comparison of cyclic voltage-time curves under the given conditions;

[0030] The electrolyte is 1M LiPF6 in EC:DEC = 1:1 Vol%. Detailed Implementation

[0031] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0032] Example 1:

[0033] like Figures 1-4 As shown, a method for preparing large-area single-crystal lithium metal includes the following steps:

[0034] S1: The lithium metal foil is placed in a halooctane solution for surface modification by chemical impregnation.

[0035] S2: A uniformly dispersed lithium halide surface layer is generated on the lithium metal surface, and the large-area single crystal growth of molten lithium metal is guided during the subsequent heat treatment process;

[0036] S3: Lithium metal is placed in an electrolyte to dissolve the lithium halide layer on the surface, resulting in a large-area single-crystal lithium foil.

[0037] In S1, the lithium metal foil has a purity of 98wt% or higher, a thickness of 50μm to 500μm, a width of 1cm to 10cm, and a length of 5cm to 25cm.

[0038] In S1, the lithium metal foil is wound in multiple turns during the processing to increase the processing area of ​​the lithium metal foil.

[0039] In S1, the halooctane is C8H. 17 F, C8H 17 Cl, C8H 17 Br, C8H 17 I can be any one or more of the following, with tetrahydrofuran as the solvent.

[0040] In a halooctane solution, the mass ratio of halooctane solute to organic solvent is 1:30 to 1:100.

[0041] The halooctane solution needs to be magnetically stirred for 1 to 10 hours beforehand to generate a uniform lithium halide surface layer on the lithium metal surface.

[0042] In S1, the surface modification treatment method is as follows: the lithium metal foil is fully immersed in halooctane solution for 1h to 10h, and then taken out and dried at room temperature for 1h to 12h.

[0043] The specific heat treatment method in S2 is as follows: starting from room temperature, the temperature is increased at a rate of 1℃ / min to 10℃ / min, and then held at 181℃ to 300℃ for 1 to 300 minutes, and finally naturally cooled to room temperature.

[0044] The electrolyte in S3 includes any one of the following: 1M LiTFSI in DOL / DME with 2% LiNO3, 0.2M LiPF6, 0.2M LiBF4, 0.8M LiDFOB in DEC:FEC = 2:1 Vol%, 1M LiTFSI in DME:DOL = 1:1 Vol%, and 1M LiPF6 in EC:DEC = 1:1 Vol%.

[0045] A lithium metal battery is obtained by the above-described preparation method.

[0046] Example 2:

[0047] This embodiment provides a method for preparing large-area single-crystal lithium metal, specifically including the following steps:

[0048] Step 1: In an argon-filled glove box, add 40 mg of C8H 17 Br was added to 2g of THF and magnetically stirred for 1h to obtain a homogeneous solution;

[0049] Step 2: After winding a lithium metal foil with a purity of 99wt%, a thickness of 50μm, and an area of ​​2cm×10cm, place it in the solution obtained in Step 1 and soak it for 1 hour.

[0050] Step 3: Take out and unfold the lithium metal foil from Step 2, and dry it at room temperature for 10 hours to obtain lithium metal modified with LiBr layer;

[0051] Step 4: The lithium metal modified with the LiBr layer prepared in Step 3 is wound and placed in a muffle furnace. The temperature is increased from room temperature to 200℃ at a rate of 2℃ / min, held for 60 min, and then naturally cooled to room temperature.

[0052] Step 5: Place the single-crystal lithium metal prepared in Step 4 into an electrolyte of 1M LiPF6 in EC:DEC = 1:1 Vol%, dissolve the LiBr layer on the surface, and then remove it to obtain a large-area single-crystal lithium metal foil.

[0053] Example 3:

[0054] This embodiment provides a method for preparing large-area single-crystal lithium metal, specifically including the following steps:

[0055] Step 1: In an argon-filled glove box, add 60 mg of C8H 17Br was added to 3g of THF and magnetically stirred for 1 hour to obtain a homogeneous solution;

[0056] Step 2: After winding a lithium metal foil with a purity of 99wt%, a thickness of 50μm, and an area of ​​3cm×10cm, place it in the solution obtained in Step 1 and soak it for 1 hour.

[0057] Step 3: Take out and unfold the lithium metal foil from Step 2, and dry it at room temperature for 10 hours to obtain lithium metal modified with LiBr layer;

[0058] Step 4: The lithium metal modified with the LiBr layer prepared in Step 3 is wound and placed in a muffle furnace. The temperature is increased from room temperature to 200℃ at a rate of 2℃ / min, held for 60 min, and then naturally cooled to room temperature.

[0059] Step 5: Place the single-crystal lithium metal prepared in Step 4 into an electrolyte of 1M LiPF6 in EC:DEC = 1:1 Vol%, dissolve the LiBr layer on the surface, and then remove it to obtain a large-area single-crystal lithium metal foil.

[0060] Example 4:

[0061] This embodiment provides a method for preparing large-area single-crystal lithium metal, specifically including the following steps:

[0062] Step 1: In an argon-filled glove box, add 50 mg of C8H 17 Br was added to 5g of THF and magnetically stirred for 2 hours to obtain a homogeneous solution;

[0063] Step 2: After winding a lithium metal foil with a purity of 99wt%, a thickness of 50μm, and an area of ​​3cm×5cm, place it in the solution obtained in Step 1 and soak it for 2 hours.

[0064] Step 3: Take out and unfold the lithium metal foil from Step 2, and dry it at room temperature for 10 hours to obtain lithium metal modified with LiBr layer;

[0065] Step 4: The lithium metal modified with the LiBr layer prepared in Step 3 is wound and placed in a muffle furnace. The temperature is increased from room temperature to 200℃ at a rate of 5℃ / min, held for 100min, and then naturally cooled to room temperature.

[0066] Step 5: Place the single-crystal lithium metal prepared in Step 4 into an electrolyte of 1M LiPF6 in EC:DEC = 1:1 Vol%, dissolve the LiBr layer on the surface, and then remove it to obtain a large-area single-crystal lithium metal foil.

[0067] Example 5:

[0068] This embodiment provides a method for preparing large-area single-crystal lithium metal, specifically including the following steps:

[0069] Step 1: In an argon-filled glove box, add 60 mg of C8H 17 Br was added to 3g of THF and magnetically stirred for 1 hour to obtain a homogeneous solution;

[0070] Step 2: After winding a lithium metal foil with a purity of 99wt%, a thickness of 500μm, and an area of ​​5cm×20cm, place it in the solution obtained in Step 1 and soak it for 1 hour.

[0071] Step 3: Take out and unfold the lithium metal foil from Step 2, and dry it at room temperature for 10 hours to obtain lithium metal modified with LiBr layer;

[0072] Step 4: The lithium metal modified with the LiBr layer prepared in Step 3 is wound and placed in a muffle furnace. The temperature is increased from room temperature to 200℃ at a rate of 2℃ / min, held for 60 min, and then naturally cooled to room temperature.

[0073] Step 5: Place the single-crystal lithium metal prepared in Step 4 into an electrolyte of 1M LiPF6 in EC:DEC = 1:1 Vol%, dissolve the LiBr layer on the surface, and then remove it to obtain a large-area single-crystal lithium metal foil.

[0074] Example 6:

[0075] This embodiment provides a method for preparing large-area single-crystal lithium metal, specifically including the following steps:

[0076] Step 1: In an argon-filled glove box, add 60 mg of C8H 17 Br was added to 3g of THF and magnetically stirred for 1 hour to obtain a homogeneous solution;

[0077] Step 2: After winding a lithium metal foil with a purity of 99wt%, a thickness of 50μm, and an area of ​​3cm×10cm, place it in the solution obtained in Step 1 and soak it for 1 hour.

[0078] Step 3: Take out and unfold the lithium metal foil from Step 2, and dry it at room temperature for 10 hours to obtain lithium metal modified with LiBr layer;

[0079] Step 4: The lithium metal modified with the LiBr layer prepared in Step 3 is wound and placed in a muffle furnace. The temperature is increased from room temperature to 300℃ at a rate of 5℃ / min, held for 300min, and then naturally cooled to room temperature.

[0080] Step 5: Place the single-crystal lithium metal prepared in Step 4 into an electrolyte of 1M LiPF6 in EC:DEC = 1:1 Vol%, dissolve the LiBr layer on the surface, and then remove it to obtain a large-area single-crystal lithium metal foil.

[0081] Example 7:

[0082] This embodiment provides a method for preparing large-area single-crystal lithium metal, specifically including the following steps:

[0083] Step 1: In an argon-filled glove box, add 60 mg of C8H 17 Br was added to 3g of THF and magnetically stirred for 1 hour to obtain a homogeneous solution;

[0084] Step 2: After winding a lithium metal foil with a purity of 99wt%, a thickness of 500μm, and an area of ​​5cm×20cm, place it in the solution obtained in Step 1 and soak it for 1 hour.

[0085] Step 3: Take out and unfold the lithium metal foil from Step 2, and dry it at room temperature for 10 hours to obtain lithium metal modified with LiBr layer;

[0086] Step 4: The lithium metal modified with the LiBr layer prepared in Step 3 is wound and placed in a muffle furnace. The temperature is increased from room temperature to 200℃ at a rate of 2℃ / min, held for 60 min, and then naturally cooled to room temperature.

[0087] Step 5: Place the single-crystal lithium metal prepared in Step 4 into an electrolyte of 0.2M LiPF6, 0.2M LiBF4, and 0.8M LiDFOB in DEC:FEC = 2:1 Vol% to dissolve the LiBr layer on the surface. After removal, a large-area single-crystal lithium metal foil is obtained.

[0088] Comparative Example 1:

[0089] This comparative example provides a method for preparing a lithium metal anode, specifically including the following steps:

[0090] Step 1: In an argon-filled glove box, add 40 mg of C8H 17 Br was added to 2g of THF and magnetically stirred for 1h to obtain a homogeneous solution;

[0091] Step 2: After winding a lithium metal foil with a purity of 99wt%, a thickness of 50μm, and an area of ​​2cm×10cm, immerse it in the solution obtained in Step 1 for 1 hour;

[0092] Step 3: Take out and unfold the lithium metal foil from Step 2, and dry it at room temperature for 10 hours to obtain lithium metal modified with LiBr layer;

[0093] Step 4: The lithium metal modified with the LiBr layer prepared in Step 3 is wound and placed in a muffle furnace. The temperature is increased from room temperature to 100℃ at a rate of 2℃ / min, held for 60min, and then naturally cooled to room temperature.

[0094] Step 5: Place the single-crystal lithium metal prepared in Step 4 into an electrolyte of 1M LiPF6 in EC:DEC = 1:1 Vol%, dissolve the LiBr layer on the surface, and then remove it to obtain a large-area single-crystal lithium metal foil.

[0095] Comparative Example 2:

[0096] This comparative example provides a method for preparing a lithium metal anode, specifically including the following steps:

[0097] Step 1: Take 2g of THF in a glove box filled with argon gas;

[0098] Step 2: After winding a lithium metal foil with a purity of 99wt%, a thickness of 50μm, and an area of ​​2cm×10cm, immerse it in the solution obtained in Step 1 for 1 hour;

[0099] Step 3: Take out the lithium metal foil from Step 2 and unfold it, then dry it at room temperature for 10 hours to obtain lithium metal modified with LiBr layer.

[0100] Step 4: The lithium metal modified with the LiBr layer prepared in Step 3 is wound and placed in a muffle furnace. The temperature is increased from room temperature to 200℃ at a rate of 2℃ / min, held for 60min, and then naturally cooled to room temperature.

[0101] Step 5: Place the single-crystal lithium metal prepared in Step 4 into an electrolyte of 1M LiPF6 in EC:DEC = 1:1 Vol%, dissolve the LiBr layer on the surface, and then remove it to obtain a large-area single-crystal lithium metal foil.

[0102] The single-crystal lithium metal anode prepared in Example 1 and the lithium metal anode prepared in Comparative Example 1 were characterized by XRD, as follows: Figure 1 The XRD patterns of lithium metal prepared according to the steps of Example 1 and Comparative Example 1 are shown.

[0103] The single-crystal lithium metal anode prepared in Example 1 and the lithium metal anode prepared in Comparative Example 1 were compared in a 1M LiPF6 in EC:DEC = 1:1 vol% electrolyte at 1 mA cm⁻¹ -2 -10mAh cm -2 Electrodeposition was performed under specific conditions, and the deposition morphology of lithium metal on the surfaces of monocrystalline and polycrystalline lithium anodes was characterized using SEM. For example... Figure 2As shown, lithium metal deposits on the surface of a single-crystal lithium anode exhibit a flat and dense blocky deposition, while on a polycrystalline lithium anode, it exhibits a dendritic lithium dendrite morphology, indicating that the single-crystal lithium metal anode has dendrite-free characteristics during battery operation.

[0104] The single-crystal lithium metal anode prepared in Example 1 and the lithium metal anode prepared in Comparative Example 1 were subjected to a 1 mA cm⁻¹ test in a 1 M LiPF₆ in EC:DEC = 1:1 vol% electrolyte. -2 -1mAh cm -2 Symmetrical cell cycle tests under certain conditions were performed and compared. For example... Figure 3 As shown, after 50 cycles, the impedance of the single-crystal lithium metal battery prepared in Example 1 is much smaller than that of Example 1. Figure 4 As shown, compared with the lithium metal anode prepared in Comparative Example 1, the symmetric cell assembled with the single-crystal lithium metal anode prepared in Example 1 can achieve stable cycling for a longer time with a lower overpotential.

[0105] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A method for preparing large-area single-crystal lithium metal, characterized in that: The preparation method comprises the following steps: S1: Li metal foil was placed in a halooctane solution for surface modification by chemical impregnation. In S1, the lithium metal foil is wound in multiple turns during the treatment process to increase the treatment area of ​​the lithium metal foil; the octane halides are C8H 17 F, C8H 17 Cl, C8H 17 Br, C8H 17 Any one or more of I, wherein the solvent is tetrahydrofuran; In the halogenated octane solution, the mass ratio of the halogenated octane solute to the organic solvent is 1:30 to 1:100; The surface modification treatment method is as follows: the lithium metal foil is immersed in a halooctane solution for 1 h to 10 h, and then taken out and dried at room temperature for 1 h to 12 h; S2: Generate a uniformly dispersed lithium halide surface layer on the lithium metal surface and guide the large-area single crystal growth of molten lithium metal during the subsequent heat treatment process; The specific method of the heat treatment in S2 is: starting from room temperature, heating at a rate of 1°C / min to 10°C / min, and then keeping the temperature at 181°C to 300°C for 1min to 300min, and finally cooling naturally to room temperature; S3: placing lithium metal into an electrolyte to dissolve the lithium halide layer on the surface to obtain a large-area single-crystalline metal lithium foil; The electrolyte in S3 includes any one of: 1 M LiTFSI in DOL / DME with 2%LiNO3, 0.2 M LiPF6, 0.2 MLiBF4, 0.8 M LiDFOB in DEC:FEC=2:1 Vol%, 1 M LiTFSI in DME:DOL=1:1 Vol%, and 1 MLiPF6 in EC:DEC=1:1 Vol%.

2. The method for preparing a large-area single-crystal lithium metal according to claim 1, characterized in that: In the S1, the lithium metal foil has a purity of 98 wt% or more, a thickness of 50 μm to 500 μm, a width of 1 cm to 10 cm, and a length of 5 cm to 25 cm.

3. The method for preparing a large-area single-crystal lithium metal according to claim 1, characterized in that: The octane halides solution needs to be stirred magnetically for 1 h to 10 h in advance to form a uniform lithium halide surface layer on the lithium metal surface.

4. A metal lithium battery, characterized in that: A metal lithium battery is obtained by adopting the preparation method described in any one of claims 1 to 3.

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