Amorphous pure lithium / lithium alloy negative electrode material, preparation method and lithium battery
Amorphous pure metallic lithium/lithium alloy anode materials were prepared by equal channel corner extrusion and roll pressing, which solved the problems of uneven deposition and dendrite growth of lithium metal anodes during battery cycling, and realized lithium batteries with high energy density and long cycle life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2026-04-20
- Publication Date
- 2026-07-10
AI Technical Summary
Existing lithium metal anode materials suffer from problems such as spontaneous reaction, volume expansion, uneven deposition, and dendrite growth during battery cycling, leading to battery capacity decay and safety hazards, making it difficult to achieve high energy density and long cycle life.
Amorphous pure metallic lithium/lithium alloy anode materials were prepared by equal channel angular extrusion and roll pressing. The lithium-ion transport kinetics were controlled to avoid side reactions and uniformly deposit lithium. The stability of the materials was ensured by operating in an inert atmosphere and without chemical treatment.
It achieves uniform lithium deposition, reduces lithium dendrite growth, improves battery safety and long-term cycle stability, and has high energy density and fast charging performance.
Smart Images
Figure CN122370321A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery anode manufacturing technology, and particularly relates to an amorphous pure metallic lithium / lithium alloy anode material, its preparation method, and a lithium battery. Background Technology
[0002] Currently, most commercially available lithium-ion batteries rely on ion insertion / extraction energy storage mechanisms using graphite anodes, with a theoretical specific capacity of only 372 mAh·g. -1 The energy density of related battery systems has approached its theoretical limit, making it difficult to meet the development needs of high-energy-density energy storage scenarios. Lithium metal anodes, due to their 3860mAh / g capacity... -1 With its ultra-high theoretical specific capacity and the lowest electrochemical potential of -3.04V (relative to the standard hydrogen electrode), it has become a core candidate anode material for building the next generation of high energy density batteries, attracting much attention from the industry and scientific research fields.
[0003] However, the practical application of lithium metal anodes is still limited by their high reactivity and the instability of electrochemical deposition kinetics, which are manifested in three aspects: First, lithium metal is prone to spontaneous reaction with the electrolyte, forming a fragile and unevenly morphological solid electrolyte interphase (SEI) film. This film is easily damaged during battery cycling, continuously consuming electrolyte and increasing interfacial impedance, ultimately causing rapid capacity decay. Second, during the electrochemical cycling process of deposition / stripping, lithium metal undergoes significant volume expansion and contraction, damaging the structural integrity of the electrode and even causing delamination between the current collector and the active material, leading to electrode failure. Third, during cycling, lithium metal is prone to uneven deposition, forming lithium dendrites. These dendrites not only irreversibly consume electrolyte and active lithium, reducing battery coulombic efficiency, but may also puncture the battery separator, causing internal short circuits and potentially inducing serious safety accidents such as thermal runaway.
[0004] To address the aforementioned issues, researchers have conducted extensive studies on lithium interface engineering. Through techniques such as alloying modification, solid-state electrolyte adaptation, electrode substrate modification, and artificial SEI film construction, some progress has been made in regulating lithium deposition behavior and suppressing lithium dendrite growth. However, the stability of lithium metal anodes prepared using existing technologies during long-term battery cycling is still far inferior to that of commercial graphite anodes. Therefore, how to precisely control the transport behavior of lithium ions at the electrode / electrolyte interface and the deposition / stripping kinetics of lithium to achieve uniform and dense lithium deposition, while effectively isolating side reactions between lithium and the electrolyte, and ensuring that the electrode structure mechanically adapts to volume deformation during cycling, ultimately developing lithium metal batteries with high energy density, fast charging performance, and long cycle life, remains the core research goal and technical challenge in the field of lithium metal anodes. Summary of the Invention
[0005] To address the aforementioned technical problems, this invention proposes an amorphous pure metallic lithium / lithium alloy anode material, its preparation method, and a lithium battery.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing an amorphous pure metallic lithium / lithium alloy anode material includes the following steps: Pure metallic lithium or lithium alloys are processed to obtain bulk pure metallic lithium or bulk lithium alloys. In an inert atmosphere, the bulk pure metallic lithium or bulk lithium alloy is extruded using an equal channel corner method, and then rolled to obtain a foil, i.e., an amorphous pure metallic lithium / lithium alloy anode material.
[0007] Furthermore, the lithium alloy has the chemical formula LiM (M = one or more of Na, K, Mg, Zn, Ca, Sn, Si, Ag, Au, Al, In and Bi); and the purity of the pure metallic lithium is greater than 99.9%.
[0008] Further, the specific steps for processing the lithium alloy are as follows: alloying lithium metal with at least one metal selected from Na, K, Mg, Zn, Ca, Sn, Si, Ag, Au, Al, In, and Bi using at least one of the following methods: melting, rolling, or electrodeposition. The specific steps for processing pure lithium metal are as follows: alloying pure lithium metal using at least one of the following methods: melting, rolling, or electrodeposition.
[0009] The specific steps for alloying using the aforementioned melting method are as follows: A thin stainless steel sheet is folded into a rectangular boat. A suitable amount of lithium alloy sheet is neatly arranged inside the stainless steel boat. The boat is then placed in a muffle furnace. The muffle furnace is heated to melt the alloy, and the molten lithium alloy is repeatedly handled with tweezers to remove the oxide film. After the oxide film is largely removed, the alloy is cooled to room temperature to obtain a block of lithium alloy. The oxide film is scraped off with a knife, and the block is cut in the center to obtain the desired size. The heating rate of the muffle furnace is between 2 and 10 °C / min, reaching a temperature of 200–700 °C. If the holding temperature is too low, the material may solidify during oxide film removal; if the holding temperature is too high, the alloy may vaporize and disappear.
[0010] Furthermore, the inert atmosphere includes an inert gas glove box (with water and oxygen content both less than 0.1 ppm), a sealed vacuum environment, or a drying room. In this invention, all operations involving pure metallic lithium or lithium alloys should be performed in an inert atmosphere.
[0011] Furthermore, the die used for extrusion processing via the equal-channel corner is a square-hole single-channel die with an outer angle Ψ between 45° and 135°, and an inner angle Φ between 45° and 135°. Generally, both the inner and outer angles can be 90° simultaneously to ensure maximum shear strain. For some harder lithium alloys (such as lithium-indium alloys), both the inner and outer angles can be 135°, with rounded corners at the die edges. The number of passes refers to the number of times the material passes through the equal-channel corner, generally between 4 and 8 passes. Fewer passes result in lower amorphization, while more passes do not significantly enhance amorphization. The extrusion rate is between 5 and 20 mm / min, because excessively slow extrusion leads to tight adhesion between the material and the die, while excessively fast extrusion results in insufficient recrystallization. For example, using a square-hole single-channel die with 90° inner and outer angles, and adopting method B... C The feeding method involves extruding the material at a rate of 8 mm / min for 8 passes to achieve a greater degree of amorphization.
[0012] Furthermore, the feeding method during extrusion processing via the equal channel angle is selected from A and B. A B C One of the four rotation methods, B, C, and D. C This method maximizes the amorphization of the material. Specifically: Method A involves non-rotating feeding and extrusion, which is repeated. Method B A After the nth discharge, the axial rotation is 90° counterclockwise for the (n+1)th feeding. After extrusion, the axial rotation is 90° clockwise for the (n+2)th feeding, and so on. Method B C After the nth extrusion, rotate the axis 90° counterclockwise and put it back into the mold. Repeat this process after the (n+1)th extrusion. Method C involves rotating the material axially by 180° after the nth extrusion and then placing it back into the mold, repeating this process.
[0013] Furthermore, the rolling process includes a preliminary thinning operation and a rolling operation. The specific steps are as follows: In the preliminary thinning operation, a hydraulic press is used to thin the sample to 2-4 mm to facilitate rolling; in the rolling operation, a rolling mill is used to perform multiple rolling operations, with each thinning operation reducing the thickness by 10-50%, thereby determining the roll spacing (e.g., for a 2 mm thick lithium foil, if a single thinning is 50%, the roll spacing for that operation is 1 mm), and finally rolling to the desired thickness and area. Excessive thinning in a single operation can lead to material cracking.
[0014] Furthermore, the rolling process employs direct rolling and / or folding rolling. The number of folding rolls is generally between 5 and 10. If the number of folds is too low, the specified thickness cannot be achieved; if the number of folds is too high, it will lead to material cracking.
[0015] The present invention also provides an amorphous pure metallic lithium / lithium alloy anode material, which is prepared by the above preparation method, and the average grain size of the anode material is 10 nm to 1 mm.
[0016] The amorphous pure lithium metal / lithium alloy anode material prepared by this invention contains a large number of ultrafine grains on its surface and in its bulk phase. This special crystal structure can enhance the mechanical stability of the lithium electrode and reduce volume fluctuations; on the other hand, it can lower the barrier for lithium ions to cross grain boundaries, accelerate the rapid transport of lithium atoms, make the lithium metal deposition uniform, and avoid dendrite formation.
[0017] The present invention also provides a lithium metal battery, comprising: a positive electrode material, a separator, an electrolyte, and the aforementioned amorphous pure lithium metal / lithium alloy negative electrode material.
[0018] Furthermore, the amorphous pure metallic lithium / lithium alloy anode material is circular with a diameter between 6 and 14 mm.
[0019] The diaphragm is a PP2500 diaphragm; The electrolyte is a commercially available electrolyte, formulated by dissolving 0.2M LiBF4, 0.8M LiDFOB, and 0.2M LiPF6 in a mixed solvent of diethyl carbonate (DEC) and ethylene carbonate (EC) in a volume ratio of 2:1. The lithium battery is a secondary lithium metal battery, and the coin cell battery is assembled using the Kejing LIR-2032 series mold.
[0020] Compared with the prior art, the present invention has the following advantages and technical effects: This invention employs a physical method of equal channel rotation, directly using amorphous pure metallic lithium / lithium alloy as the processing substrate, without introducing other chemical reagents or chemical treatment processes. The operation is green, environmentally friendly, and easily industrialized. This invention focuses on controlling the crystal structure to achieve an amorphous structure of metallic lithium (alloy), effectively reducing the lithium-ion deposition diffusion barrier, mitigating side reactions between lithium metal and electrolyte, and solving the dendrite growth problem. The amorphous pure metallic lithium / lithium alloy anode material prepared by this invention has an amorphous structure, long-range disorder, and relatively uniformity, thereby greatly improving the lithium-ion transport dynamics on the electrode surface, promoting uniform lithium deposition, and ensuring the safety and long-term cycle stability of the battery system. Attached Figure Description
[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 Scanning electron microscope images of the negative electrode material prepared in Example 1 (right) and the negative electrode material provided in Comparative Example 1 (left); Figure 2 XRD patterns of the negative electrode materials prepared in Examples 1 and 4 and the commercial lithium sheet provided in Comparative Example 1; Figure 3 Comparison of cycling tests of symmetric cells prepared with electrode materials for Comparative Example 1 and Comparative Example 2; Figure 4 Comparison of cycle tests of symmetrical batteries prepared with the negative electrode materials of Example 4 and Comparative Example 2. Detailed Implementation
[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0027] This invention requires operation entirely under an inert atmosphere, which can be water, an inert gas glove box with an oxygen content of less than 0.1 ppm, a sealed vacuum environment, or a drying room. The purity of the pure metallic lithium must be greater than 99.9%, and the lithium alloy must be LiM (M is one or more of Na, K, Mg, Zn, Ca, Sn, Si, Ag, Au, Al, In, and Bi). For example, in the following embodiments of this invention, the lithium alloy can be selected from lithium-magnesium alloy, lithium-indium alloy, lithium-zinc alloy, or lithium-sodium alloy.
[0028] I. Preparation of bulk pure metallic lithium / lithium alloy (I) Preparation of bulk pure metallic lithium Commercial lithium metal sheets with a purity greater than 99.9% are directly selected and processed into block-shaped pure lithium metal of the required size for later use.
[0029] (II) Preparation of bulk lithium alloys Alloying: alloying lithium metal with at least one metal M by at least one of the following methods: melting, rolling, or electrodeposition; or alloying pure lithium metal by at least one of the following methods: melting, rolling, or electrodeposition.
[0030] For example, the refined operation of the melting method (preferred): ① Take a thin stainless steel sheet and fold it into a rectangular boat, and neatly place an appropriate amount of lithium alloy sheet into the boat; ② Place the stainless steel boat in a muffle furnace and heat it to 200-700℃ (e.g., 200℃, 250℃, 300℃, 400℃ or 550℃) at a heating rate of 2-10℃ / min (e.g. 5℃ / min) to melt it. During the process, use tweezers to pick up the molten lithium alloy several times to remove the surface oxide film; ③ After the oxide film is basically removed, cool it with the furnace at room temperature to obtain a block lithium alloy; ④ Use a scalpel to scrape off the residual oxide film on the surface of the block lithium alloy, cut it along the middle, and obtain a block lithium alloy of the required size for later use.
[0031] II. Equal Channel Corner Extrusion Processing 1. Mold selection: Use a square hole single-channel mold with an outer angle Ψ and an inner angle Φ of 45-135° (e.g., both inner and outer angles are 60°, 90°, or 135°). For conventional systems, select 90° inner and outer angles (to ensure maximum shear strain). For harder lithium alloys such as lithium-indium alloys, select 135° inner and outer angles, and make rounded corners at the mold corners. 2. Feeding method: Select A or B A B C One of the four rotation methods (B is preferred) C Method (highest degree of amorphization), the operation of each method is as follows: Method A: Feed without rotating and extrude, repeat the operation; Method B AAfter the nth discharge, the axial rotation is 90° counterclockwise for the (n+1)th feeding. After extrusion, the axial rotation is 90° clockwise for the (n+2)th feeding. This operation is repeated. Method B C After the nth extrusion, rotate the axis 90° counterclockwise and put it back into the mold. Repeat the operation after the (n+1)th extrusion. Method C: After the nth extrusion, rotate 180° axially and then put it back into the mold, repeating the operation; Extrusion parameters: Place the block of pure metallic lithium / lithium alloy into the die and extrude at a rate of 5–20 mm / min for 4–8 passes (too few passes result in low amorphization, too many passes do not significantly improve amorphization); Optimal parameters: Die with 90° inner and outer angles + B C Feed method + 8mm / min extrusion rate + 8 passes; 3. Post-processing: After extrusion, cut off the portion of the sample that did not pass through the corner and set it aside for later use.
[0032] III. Roll forming process for preparing amorphous pure lithium metal / lithium alloy anode foil 1. Preliminary thinning: Place the squeezed sample into a self-sealing bag and slowly thin it to 2-4mm (e.g., 3mm, 3mm or 4mm) using a hydraulic press. 2. Multiple rolling: Place the initially thinned sample in a rolling mill and roll it. The thickness reduction in a single roll should be controlled between 10% and 50% (the roll spacing should be determined according to the reduction ratio. For example, if a 2mm sample is reduced by 50% in a single roll, the roll spacing should be set to 1mm). Avoid excessive thinning in a single roll, which may cause the material to crack. 3. Rolling method: At least one of direct rolling or folding rolling can be used; if folding rolling is used, the number of folding rolling cycles should be controlled between 5 and 10 (too few cycles will not achieve the target thickness, and too many cycles will easily cause cracking). 4. Finished product preparation: After multiple rolling processes, foil of the required thickness and area is obtained, which is the amorphous pure metallic lithium / lithium alloy anode material (average grain size 10nm~1mm, with a large number of ultrafine grains on the surface and in the bulk phase).
[0033] IV. Negative Electrode Forming The prepared amorphous pure lithium metal / lithium alloy negative electrode foil is punched into a circular electrode with a diameter controlled between 6 and 14 mm, and then set aside for later use.
[0034] V. Lithium Metal Battery Assembly (Taking Kejing LIR-2032 Series Button Cell Battery as an Example) 1. Raw material selection: Cathode: A variety of cathode materials are available, including embedded, conversion, and embedded / conversion composite materials. Diaphragm: PP 2500 diaphragm; Electrolyte: 0.2M LiBF4 (lithium tetrafluoroborate), 0.8M LiDFOB (lithium difluorooxalate borate), and 0.2M LiPF6 (lithium hexafluorophosphate) were dissolved in a mixed solvent of diethyl carbonate (DEC) and ethylene carbonate (EC) in a volume ratio of 2:1 to prepare a commercial electrolyte. 2. Assembly Operation: Under an inert atmosphere, assemble the Kejing LIR-2032 series button battery in the following order: "positive electrode shell → positive electrode material → electrolyte → separator → electrolyte → amorphous pure lithium metal / lithium alloy circular negative electrode → gasket → spring sheet → negative electrode shell". After completion, seal the battery to obtain a lithium metal secondary battery.
[0035] In the following embodiments of the present invention, the test temperature is a constant 30°C and the current density is 1 mA·cm² during performance testing. -1 The deposition capacity is 1 mAh·cm³. -1 The cutoff voltage is -5 to 5V.
[0036] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.
[0037] All raw materials used in this invention were purchased from the market.
[0038] The technical solution of the present invention will be further illustrated by the following embodiments.
[0039] The following embodiments of the present invention require operation in an inert atmosphere throughout. Specifically, the inert atmosphere used is an inert gas glove box with a water and oxygen content of less than 0.1 ppm.
[0040] Example 1 A method for preparing an amorphous pure metallic lithium anode material, comprising the following steps: S1. Preparation of bulk pure lithium metal: Take a thin stainless steel sheet and fold it into a rectangular boat (8×8×50mm, opening upwards). Arrange 60 commercial lithium metal sheets with a purity >99.9% and a thickness of 450μm neatly in the boat. Place the stainless steel boat in a muffle furnace and heat it from 20℃ to 300℃ in 60min at a heating rate of 5℃ / min. Then, hold it at 300℃ for 40min (the first 60min is for melting, and the last 40min is for removing the oxide film). During the process, use tweezers to repeatedly pick up the molten pure lithium metal to remove the surface oxide film. After the oxide film is basically removed, cool it with the furnace at room temperature to obtain bulk pure lithium metal. Use a scalpel to scrape off the residual oxide film on the surface of the bulk pure lithium metal and cut it along the middle to obtain 8×8×25mm bulk pure lithium metal. S2. Equal Channel Corner Extrusion Processing: The obtained blocky pure lithium metal is placed into an equal channel corner die (square 8×8mm channel, outer angle Ψ is 90°, inner angle Φ is 90°), the extrusion speed is 20mm / min, and B is used.C Method (after the nth extrusion, rotate 90° counterclockwise along the axis and put it back into the mold; after the (n+1)th extrusion, rotate 90° clockwise along the axis and put it back into the mold, and repeat this process), extrude 4 times; cut off the part that did not pass through the corner with a scalpel; S3. Roll forming process for preparing amorphous pure metal lithium anode foil: The extruded sample after cornering is initially thinned by placing the sample in a self-sealing bag and slowly thinning it to about 2mm using a hydraulic press. Then, a roll forming operation is performed, rolling along the extrusion direction without folding, gradually thinning it to 2mm → 1.5mm → 1mm → 0.7mm → 0.4mm → 0.2mm (200μm). S4. Negative electrode forming: The prepared amorphous pure lithium metal negative electrode foil is punched into a circular electrode with a diameter of 10 mm.
[0041] The electrodes prepared in this embodiment are assembled into a symmetrical cell.
[0042] Example 2 A method for preparing a lithium-magnesium alloy anode material, comprising the following steps: S1. Preparation of bulk lithium alloy: Take a thin stainless steel sheet and fold it into a rectangular boat (8×8×50mm, opening upwards). Mix 9g of metallic lithium and 1g of metallic magnesium thoroughly to obtain a bulk lithium-magnesium alloy, and place it in the boat. Place the stainless steel boat in a muffle furnace and heat it from 20℃ to 500℃ in 60min at a heating rate of 5℃ / min. Then, hold it at 500℃ for 40min. During the process, use tweezers to repeatedly pick up the molten lithium-magnesium alloy to remove the surface oxide film. After the oxide film is basically removed, cool it with the furnace at room temperature to obtain a bulk lithium-magnesium alloy. Use a scalpel to scrape off the residual oxide film on the surface of the bulk lithium-magnesium alloy and cut it along the middle to obtain a bulk lithium-magnesium alloy of 8×8×25mm. S2. Equal channel corner extrusion processing: The obtained block lithium-magnesium alloy is placed into an equal channel corner mold (square 8×8mm channel, outer angle Ψ between 120°, inner angle Φ between 120°), the extrusion speed is 10mm / min, and method A is used (feeding without rotation and extruding, repeating this process), extruding 2 times; the part that has not passed through the corner is removed with a scalpel; S3. Roll forming process for preparing lithium-magnesium alloy negative electrode foil: The extruded sample after cornering is initially thinned by placing the sample in a self-sealing bag and slowly thinning it to about 2mm using a hydraulic press. Then, the sample is rolled without folding along the extrusion direction, gradually thinning it to 2mm → 1.5mm → 1mm → 0.7mm → 0.4mm → 0.2mm (200μm). S4. Negative electrode forming: The prepared lithium-magnesium alloy negative electrode foil is punched into a circular electrode with a diameter of 10mm.
[0043] The electrodes prepared in this embodiment are assembled into a symmetrical cell.
[0044] Example 3 A method for preparing a lithium-indium alloy anode material, comprising the following steps: S1. Preparation of bulk lithium alloy: Take a thin stainless steel sheet and fold it into a rectangular boat (8×8×50mm, opening upwards). Mix 9g of metallic lithium and 1g of metallic indium thoroughly and place them into the boat. Place the stainless steel boat in a muffle furnace and heat it from 20℃ to 200℃ in 60min at a heating rate of 5℃ / min. Then, hold it at 200℃ for 40min. During the process, use tweezers to repeatedly pick up the molten lithium-indium alloy to remove the surface oxide film. After the oxide film is basically removed, cool it with the furnace at room temperature to obtain a bulk lithium-indium alloy. Use a scalpel to scrape off the residual oxide film on the surface of the bulk lithium-indium alloy and cut it along the middle to obtain a bulk lithium-indium alloy of 8×8×25mm. S2. Equal Channel Corner Extrusion Processing: The obtained block-shaped lithium-indium alloy is placed into an equal channel corner mold (square 8×8mm channel, outer angle Ψ between 90°, inner angle Φ between 90°), the extrusion speed is 10mm / min, and the C method is used (after the nth extrusion, rotate axially 180° and put it back into the mold, and repeat this process), and the extrusion is performed 12 times; the part that has not passed through the corner is removed with a scalpel; S3. Roll forming process for preparing lithium indium alloy negative electrode foil: The extruded sample after cornering is initially thinned by placing the sample in a self-sealing bag and slowly thinning it to about 2mm using a hydraulic press. Then, a roll forming operation is performed, rolling along the extrusion direction without folding, gradually thinning it to 2mm → 1.5mm → 1mm → 0.7mm → 0.4mm → 0.2mm (200μm). S4. Negative electrode forming: The prepared lithium indium alloy negative electrode foil is punched into a circular electrode with a diameter of 12mm.
[0045] The electrodes prepared in this embodiment were assembled into a secondary full cell.
[0046] Example 4 A method for preparing an amorphous pure metallic lithium anode material, comprising the following steps: S1. Preparation of bulk pure lithium metal: Take a thin stainless steel sheet and fold it into a rectangular boat (8×8×50mm, opening upwards). Arrange 60 commercial lithium metal sheets with a purity >99.9% and a thickness of 450μm neatly in the boat. Place the stainless steel boat in a muffle furnace and heat it from 20℃ to 300℃ in 60min at a heating rate of 5℃ / min. Then hold it at 300℃ for 40min (the first 60min is for melting, and the last 40min is for removing the oxide film). During the process, use tweezers to repeatedly pick up the molten pure lithium metal to remove the surface oxide film. After the oxide film is basically removed, cool it with the furnace at room temperature to obtain bulk pure lithium metal. Use a scalpel to scrape off the residual oxide film on the surface of the bulk pure lithium metal and cut it along the middle to obtain 8×8×25mm bulk pure lithium metal. S2. Equal Channel Corner Extrusion Processing: The obtained blocky pure lithium metal is placed into an equal channel corner die (square 8×8mm channel, outer angle Ψ between 90°, inner angle Φ between 90°), and the extrusion speed is 30mm / min, using B... C Method (after the nth extrusion, rotate 90° counterclockwise along the axis and put it back into the mold; after the (n+1)th extrusion, rotate 90° clockwise along the axis and put it back into the mold, and repeat this process), extrude 8 times; cut off the part that did not pass through the corner with a scalpel; S3. Roll forming process for preparing amorphous pure lithium metal anode foil: The extruded sample after cornering is initially thinned by placing it in a self-sealing bag and slowly thinning it to about 3mm using a hydraulic press. Then, a roll forming operation is performed, gradually rolling it to 200μm. Subsequently, the lithium metal is folded by winding and rolled repeatedly 10 times. The roll spacing is adjusted to 0.3mm, and the lithium metal is folded by winding and rolled repeatedly 10 times. The roll spacing is adjusted to 0.1mm, and the lithium metal is folded by winding and rolled repeatedly 10 times. After the above roll forming process, the lithium metal sample is processed into a lithium foil with a thickness of 50μm. S4. Negative electrode forming: The prepared amorphous pure lithium metal negative electrode foil is punched into a circular electrode with a diameter of 12mm.
[0047] The electrodes prepared in this embodiment were assembled into a full cell.
[0048] Example 5 A method for preparing a lithium-zinc alloy anode material, comprising the following steps: S1. Preparation of bulk lithium alloy: Take a thin stainless steel sheet and fold it into a rectangular boat (8×8×50mm, opening upwards). Mix 9g of metallic lithium and 1g of metallic zinc thoroughly and place them into the boat. Place the stainless steel boat in a muffle furnace and heat it from 20℃ to 250℃ in 60min at a heating rate of 5℃ / min. Then hold it at 250℃ for 40min. During the process, use tweezers to pick up the molten lithium alloy several times to remove the surface oxide film. After the oxide film is basically removed, cool it with the furnace at room temperature to obtain a bulk lithium-zinc alloy. Use a scalpel to scrape off the residual oxide film on the surface of the bulk lithium-zinc alloy and cut it along the middle to obtain a bulk lithium-zinc alloy of 8×8×25mm. S2. Equal Channel Corner Extrusion Processing: The obtained block-shaped lithium-zinc alloy is placed into an equal channel corner die (square 8×8mm channel, outer angle Ψ between 120°, inner angle Φ between 120°), and the extrusion speed is 8mm / min. First, extrusion is performed twice using method A, and then through method B. C The method involves squeezing four times; the portion that did not pass through the corner is removed with a scalpel; S3. Roll forming process for preparing lithium-zinc alloy negative electrode foil: The extruded sample after the corner is initially thinned. The sample is placed in a self-sealing bag and slowly thinned to about 2mm using a hydraulic press. Then, the rolling operation is performed. The sample is rolled along the extrusion direction without folding, and the thickness is reduced by 50% in one go, gradually thinning to 0.2mm. S4. Negative electrode forming: The prepared lithium-zinc alloy negative electrode foil is punched into a circular electrode with a diameter of 8mm.
[0049] The electrodes prepared in this embodiment were assembled into a secondary full cell.
[0050] Example 6 A method for preparing a lithium-sodium alloy anode material, comprising the following steps: S1. Preparation of bulk lithium alloy: Fold a thin stainless steel sheet into a rectangular boat (8×8×50mm, opening upwards). Mix 9g of metallic lithium and 1g of metallic sodium thoroughly and place them into the boat. Place the stainless steel boat in a muffle furnace and heat it from 20℃ to 200℃ in 60min at a heating rate of 5℃ / min. Then hold it at 200℃ for 40min. During the process, use tweezers to repeatedly pick up the molten lithium alloy to remove the surface oxide film. After the oxide film is basically removed, cool it with the furnace at room temperature to obtain a bulk lithium-sodium alloy. Use a scalpel to scrape off the residual oxide film on the surface of the bulk lithium-sodium alloy and cut it along the middle to obtain a bulk lithium-sodium alloy of 8×8×25mm. S2. Equal Channel Corner Extrusion Processing: The obtained block-shaped lithium-sodium alloy is placed into an equal channel corner die (square 8×8mm channel, outer angle Ψ between 90°, inner angle Φ between 90°), and the extrusion speed is 15mm / min. First, B... AThe procedure involves two compressions, followed by four compressions using method C; the portion that did not pass through the corner is removed with a scalpel. S3. Roll forming process for preparing lithium-sodium alloy negative electrode foil: The extruded sample after the corner is initially thinned. The sample is placed in a self-sealing bag and slowly thinned to about 1 mm using a hydraulic press. Then, the rolling operation is performed. The sample is rolled along the extrusion direction without folding, and the thickness is reduced by 20% at a time, gradually thinning to 450 μm. S4. Negative electrode forming: The prepared lithium-sodium alloy negative electrode foil is punched into a circular electrode with a diameter of 10 mm.
[0051] The electrodes prepared in this embodiment were assembled into a secondary full cell.
[0052] Comparative Example 1 Commercial lithium sheets were used as the anode material (thickness 450μm, diameter 12mm).
[0053] The electrodes provided in the comparative preparation were assembled into a symmetrical cell.
[0054] Comparative Example 2 A thin stainless steel sheet was folded into a rectangular boat (8×8×50mm, opening upwards). A commercial lithium metal sheet with a purity >99.9% and a thickness of 450μm was placed inside the boat. The stainless steel boat was placed in a muffle furnace and heated from 20℃ to 300℃ in 60 minutes at a heating rate of 5℃ / min. It was then held at 300℃ for 40 minutes. During the process, the molten lithium metal was repeatedly picked up with tweezers to remove the surface oxide film. After the oxide film was basically removed, the furnace was cooled to room temperature to obtain a block of lithium metal. The remaining oxide film on the surface of the block of lithium metal was scraped off with a scalpel and cut along the middle to obtain a sheet of pure lithium metal measuring 8×8×25mm. This sheet was used as the negative electrode material to form a symmetrical battery.
[0055] Figure 1 Scanning electron microscope (SEM) images of the negative electrode material prepared in Example 1 (right) and the negative electrode material provided in Comparative Example 1 (left) show the grain size. Under a uniform scale (100 μm or other), each grain is assumed to be spherical with a diameter of ( ). The diameter is the grain size. The actual grain area can be determined using ImageJ software. The results show that the grain size of the negative electrode material prepared in Example 1 is between 10 nm and 10 μm, while the grain size of the commercial lithium sheet in Comparative Example 1 is between 30 and 50 μm.
[0056] Amorphous / quasi-amorphous XRD patterns have the following characteristics: the XRD peak diffraction intensity of the sample is significantly reduced compared to the control sample or standard card, appearing as multiple short peaks. The amorphous / quasi-amorphous standard considers the degree of amorphization (DA) = 1 / (half-width at half maximum ÷ average baseline height) to reflect the degree of amorphization; the higher this value, the higher the degree of amorphization. Figure 2 The XRD patterns of the negative electrode materials prepared in Examples 1 and 4 and the commercial lithium sheet provided in Comparative Example 1 are shown in the figures. It can be seen from the figures that using B... C Method 4: DA was significantly higher than B. C Method 8 extrusion and Comparative Example 1 provided commercial lithium sheet DA.
[0057] Figure 3 The graph shows a comparison of the symmetrical battery cycling tests prepared with the electrode materials of Comparative Example 1 and Comparative Example 2. It can be seen from the graph that the impedance of Comparative Example 2 is close to that of Comparative Example 1, but its nucleation overpotential and overpotential are both higher than those of Comparative Example 1. However, as cycling progresses, the overpotential of Comparative Example 2 gradually approaches that of Comparative Example 1.
[0058] Figure 4 The graph shows a comparison of the cycle tests of symmetrical batteries prepared with the negative electrode materials of Example 4 and Comparative Example 2. As can be seen from the graph, after the interface stabilizes, the impedance of Comparative Example 2 is close to that of Comparative Example 4. However, as cycling continues, the impedance of Comparative Example 2 gradually increases, while the impedance of Comparative Example 4 remains relatively stable. The overpotentials of Comparative Example 2 and Comparative Example 4 are similar.
[0059] In summary, the electrode prepared by this invention can induce uniform and dense deposition of lithium metal, without lithium dendrite growth and with small volume fluctuations. Secondary full cells or symmetric cells assembled with it exhibit superior cycle performance and service life.
[0060] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for preparing an amorphous pure metallic lithium / lithium alloy anode material, characterized in that, Includes the following steps: Pure metallic lithium or lithium alloys are processed to obtain bulk pure metallic lithium or bulk lithium alloys. In an inert atmosphere, the bulk pure metallic lithium or bulk lithium alloy is extruded using an equal channel corner method, and then rolled to obtain a foil, i.e., an amorphous pure metallic lithium / lithium alloy anode material.
2. The method for preparing the amorphous pure metallic lithium / lithium alloy anode material according to claim 1, characterized in that, The alloying elements in the lithium alloy include one or more of Na, K, Mg, Zn, Ca, Sn, Si, Ag, Au, Al, In and Bi; the purity of the pure metallic lithium is greater than 99.9%.
3. The method for preparing the amorphous pure metallic lithium / lithium alloy anode material according to claim 1, characterized in that, The specific steps for processing pure lithium metal or lithium alloys are as follows: after mixing pure lithium metal or alloying elements with lithium metal, alloying is carried out by at least one of melting, rolling or electrodeposition.
4. The method for preparing the amorphous pure metallic lithium / lithium alloy anode material according to claim 1, characterized in that, The die used for extrusion processing through the equal channel corner is a square hole single channel with an outer angle Ψ between 45 and 135°, an inner angle Φ between 45 and 135°, an extrusion pass of 4 to 8 times, and an extrusion rate of 5 to 20 mm / min.
5. The method for preparing the amorphous pure metallic lithium / lithium alloy anode material according to claim 4, characterized in that, The feeding method for extrusion processing via the equal channel angle is selected from A and B. A B C At least one of the four rotation methods, specifically: Method A involves linear feeding and extrusion, which is repeated. Method B A After the nth discharge, the axial rotation is 90° counterclockwise for the (n+1)th feeding. After extrusion, the axial rotation is 90° clockwise for the (n+2)th feeding, and so on. Method B C After the nth extrusion, rotate the axis 90° counterclockwise and then put it back into the mold; after the (n+1)th extrusion, rotate the axis 90° clockwise and then put it back into the mold, and repeat this process. Method C involves rotating the material axially by 180° after the nth extrusion and then placing it back into the mold, repeating this process.
6. The method for preparing the amorphous pure metallic lithium / lithium alloy anode material according to claim 1, characterized in that, The rolling process includes a preliminary thinning operation and a rolling operation. The specific steps are as follows: the sample is thinned to 2-4 mm using a hydraulic press; then, the sample is rolled multiple times using a rolling press, with each thinning operation reducing the thickness by 10-50%.
7. The method for preparing the amorphous pure metallic lithium / lithium alloy anode material according to claim 1, characterized in that, The rolling process employs direct rolling and / or folding rolling methods.
8. An amorphous pure metallic lithium / lithium alloy anode material, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.
9. A lithium metal battery, characterized in that, include: Positive electrode material, separator, electrolyte, and the amorphous pure metallic lithium / lithium alloy negative electrode material as described in claim 8.
10. The lithium metal battery according to claim 9, characterized in that, The diaphragm is a PP2500 diaphragm; The electrolyte is prepared by dissolving 0.2M LiBF4, 0.8M LiDFOB, and 0.2M LiPF6 in a mixed solvent of diethyl carbonate and ethylene carbonate in a volume ratio of 2:
1. The lithium battery is a secondary lithium metal battery, and the coin cell battery is assembled using the Kejing LIR-2032 series mold.