An ultrathin lithium metal anode material with (110) crystal plane orientation, its continuous preparation method and application
By hot-pressing molten lithium onto an MXene base film, an ultrathin lithium foil with a preferred orientation of the (110) crystal plane was prepared, which solved the problems of cycle stability and energy density limitation of lithium metal anodes, and realized the preparation of high energy density lithium metal batteries and the pre-lithiation of traditional lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2026-03-09
- Publication Date
- 2026-06-02
AI Technical Summary
Existing lithium metal anodes suffer from dendrite formation and interface layer rupture due to volume changes and high reactivity during charge and discharge, resulting in poor cycle stability. Furthermore, traditional processes struggle to produce thin and uniform lithium foil, limiting the improvement of battery energy density.
By hot-pressing molten lithium onto an MXene-based film or a modified copper current collector, and using the (110) crystal plane for preferential orientation growth, an ultrathin MXene-based film-lithium metal composite foil was prepared, achieving uniform deposition and high stability.
The prepared ultrathin lithium foil material has excellent electrochemical performance and cycle stability, enabling the preparation of high-energy-density lithium metal batteries, and is suitable for the pre-lithiation treatment of traditional lithium-ion batteries.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery material technology, and particularly relates to lithium metal anode materials, preparation methods and lithium metal batteries or anode pre-lithiation technology containing them, specifically to an ultrathin lithium metal anode material with (110) crystal plane orientation and its continuous preparation method and electrochemical application. Background Technology
[0002] With the rapid development of new energy vehicles, the low-altitude economy, and other high-specific-energy storage technologies, higher demands are being placed on battery energy density. However, current commercial lithium-ion batteries are already approaching their energy density limits due to the specific capacity limitations of their positive and negative electrodes. Therefore, there is an urgent need to develop positive and negative electrode materials with higher specific capacities. Compared to positive electrode materials, negative electrode materials have greater potential for capacity improvement.
[0003] Lithium metal is considered an ideal anode material for realizing next-generation high-energy-density batteries due to its extremely high theoretical specific capacity of 3860 mAh / g and the lowest electrochemical potential (-3.04 V vs. SHE).
[0004] However, lithium metal anodes exhibit “infinite” volume changes during charge and discharge, and their high reactivity leads to the continuous decomposition of the electrolyte. As deposition / stripping proceeds, the interface layer continuously breaks down and rebuilds, resulting in the formation of dendrites and “dead lithium,” which in turn reduces the battery’s charge and discharge efficiency and may even cause battery short circuits and thermal runaway, severely hindering the practical application of lithium metal anodes.
[0005] To alleviate the aforementioned problems, existing technologies mainly improve the cycle stability of lithium metal anodes by constructing three-dimensional current collectors, introducing artificial interface layers, and optimizing electrolyte systems. In particular, controlling lithium deposition behavior through crystal orientation shows significant advantages. The (110) crystal plane is a close-packed facet of lithium metal with a bcc structure, possessing the lowest surface energy. The migration energy barrier of lithium ions on the (110) crystal plane is the lowest, which is conducive to the uniform deposition of lithium metal and suppresses dendrite formation. Although these strategies improve the cycle stability of lithium metal anodes to some extent, they generally rely on a large amount of excess lithium metal, typically using lithium foil with a thickness greater than 100 μm as the anode, resulting in low lithium metal utilization and limiting the actual energy density of the battery.
[0006] From a practical application perspective, to achieve energy densities exceeding 400 Wh / kg, there is an urgent need to develop ultrathin lithium metal anodes. For example, with an areal capacity of approximately 3 mAh / cm²... 2 Under the conditions of matching commercial cathode materials and a 1:1 capacity ratio between the cathode and anode, the required lithium metal thickness is only about 15 μm, far less than the thickness of existing commercial lithium foils. However, due to the low mechanical strength, high chemical activity, and poor processing performance of lithium metal, traditional rolling processes are difficult to use to produce such thin lithium foils.
[0007] As a new class of two-dimensional materials, transition metal carbides / nitrides (MXenes) were first discovered by Gogotsi's team in 2011. The formula for MXenes materials is M... n+1 X n T x (n=1, 2, or 3), where M represents a transition metal atom (such as Ti, V, Nb, and Mo), X represents carbon and / or nitrogen, and T represents a transition metal atom (such as Ti, V, Nb, and Mo). x Representing surface end groups (such as -O, -F, or -OH), MXenes materials are typically obtained by selectively etching the atom layer (usually Al) in the MAX phase. MXenes possess excellent electrical conductivity and abundant surface functional groups, thus exhibiting high commercial potential. Furthermore, MXenes also possess hydrophilicity, ease of processing, and high yield, offering broad application prospects in catalysis, electrochemical energy storage, and other fields.
[0008] The molten lithium wetting process, which has been developed in recent years, provides a direct and effective way to prepare ultrathin lithium metal with controllable thickness. However, molten lithium has insufficient wettability on most substrates, especially copper current collectors commonly used in anodes, making it impossible to achieve uniform, large-scale, and thickness-controllable lithium metal coating.
[0009] Therefore, the development of ultrathin lithium metal foil with preferred orientation of (110) crystal plane and controllable thickness, especially its continuous preparation technology, is of great significance for realizing high energy density batteries. Summary of the Invention
[0010] To address the above problems, this invention provides an ultrathin MXene-lithium metal composite foil with a (110) crystal plane preferred orientation and its preparation method. Molten liquid lithium metal is uniformly hot-pressed onto an MXene-based film or an MXene-modified copper current collector. During the solidification process of the lithium metal, it is epitaxially grown on the MXene surface through the (110) crystal plane, exhibiting a high (110) crystal plane preferred orientation and good electrochemical performance.
[0011] Furthermore, the present invention also provides the application of the ultrathin MXene-lithium metal composite foil with preferred orientation of (110) crystal plane in the preparation of high energy density lithium metal batteries.
[0012] Furthermore, the present invention also provides the application of the ultrathin MXene-lithium metal composite foil with preferred orientation of (110) crystal plane in the prelithiation of traditional lithium-ion battery anode materials (such as graphite, silicon carbide, silicon suboxide, etc.).
[0013] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: A method for preparing an ultrathin MXene-lithium metal composite foil with (110) crystal plane orientation includes the following steps: Step 1: Synthesize MXene dispersion; Step 2: Prepare a two-dimensional metal carbon / nitrogen compound (MXene) base film or MXene-modified copper current collector and use it as a substrate. The two-dimensional metal carbon / nitrogen compound (MXene) base film is obtained by preparing the MXene dispersion in Step 1 onto an aqueous filter membrane through methods such as vacuum filtration, spraying or scraping. Step 3: Under a protective atmosphere, heat the lithium source to a molten state to obtain liquid lithium metal; use a heat-resistant tool to scrape the surface of the liquid lithium metal until a fresh and bright surface is exposed; Step 4: Liquid lithium metal is adhered to the surface of a two-dimensional metal carbon / nitrogen compound (MXene) base film or MXene-modified copper current collector as a coating by hot stamping, and it is spread evenly. The thickness of the lithium metal coating is controlled by adjusting the lithium loading. Then it is cooled to room temperature to obtain an ultrathin MXene base film-lithium metal composite foil with (110) crystal orientation, which can be used as a negative electrode material.
[0014] Furthermore, in step 1, the MXene dispersion is synthesized using the MILD method, specifically as follows: Place the HCl aqueous solution, HF aqueous solution and LiF in a reaction vessel, and then slowly add MAX; Place the reactor in an oil bath at 30-60℃ and react with stirring for 18-30 h. After the reaction is complete, wash the product, centrifuge, remove the supernatant, and repeat the above steps until the pH of the supernatant reaches about 7 to obtain the washed mixture. Then, LiCl was added to the washed mixture, and the mixture was stirred at room temperature for 2-6 h. The product was then washed and centrifuged to obtain a dispersion. The dispersion was ultrasonically treated at -10 to -5℃ for 0.5-1.5 h, centrifuged, and the supernatant was retained as the MXene dispersion. The ultrasonic power was 50-300 W.
[0015] Specifically, the ratio of HCl aqueous solution, HF aqueous solution and LiF is (10~15) mL : (1~5) mL : (1~5) g.
[0016] Specifically, the mass ratio of LiF to MAX is (1~5):1.
[0017] Specifically, the concentration of the HCl aqueous solution is 5~10 M, and the mass fraction of the HF aqueous solution is 40~60 wt.%.
[0018] Specifically, the amount of LiCl added is 1~2g, or the mass ratio of LiCl to MAX is (1~3):1.
[0019] Specifically, MAX is any one of Ti3AlC2, Ti2AlC, TiNbAlC, V2AlC, Nb2AlC, Nb4AlC3, Ti3AlCN, Ti3SiC2, Ti2SiC, TiNbSiC, V2SiC, Nb2SiC, Nb4SiC3, and Ti3SiCN.
[0020] Furthermore, the two-dimensional metal carbon / nitrogen compound (MXene) mentioned in step 1 is Ti3C2T containing end groups such as -F, -O, and -OH. x (T represents the end base), or other MXenes (such as Nb2CT). x Nb4C3T x V2CT x V4C3T x Mo2CT x wait).
[0021] Furthermore, the two-dimensional metal carbon / nitrogen compound (MXene) based film described in step 2 is prepared by the following steps: The MXene dispersion was pumped onto an aqueous filter membrane (e.g., a mixed cellulose filter membrane, Shanghai Xinya Purification Devices Factory, pore size 0.22 μm) and vacuum dried at 20-50℃ for 6-18 h to obtain the MXene base membrane.
[0022] Specifically, the volume of MXene dispersion used is 0.5~3 mL; the concentration of MXene dispersion is 2~10 mg / mL.
[0023] Furthermore, the thickness of the MXene base film mentioned in step 2 is 1 μm to 10 μm.
[0024] Furthermore, the MXene-modified copper current collector described in step 2 is prepared through the following steps: 0.05–2 mL of MXene dispersion was coated onto a commercial copper foil current collector (9 μm thick, single-sided polished, KELUDE) using a 10–100 μm doctor blade and then vacuum dried at 50–70 °C for 6–18 h to obtain MXene-modified copper foil current collector.
[0025] Specifically, the amount of MXene dispersion used is 0.05~2 mL; the concentration of MXene dispersion is 2~10 mg / mL.
[0026] Specifically, the thickness of the MXene coating is 0.1~2 μm.
[0027] Furthermore, the MXene-modified copper current collector mentioned in step 2 is obtained by coating the MXene dispersion onto the copper current collector by methods such as spraying or scraping.
[0028] Furthermore, the thickness of the MXene coating in the MXene-modified copper current collector described in step 2 is 0.1 μm to 2 μm.
[0029] Furthermore, the protective atmosphere described in step 3 is formed by one or more of nitrogen, argon, and helium.
[0030] Furthermore, the lithium source mentioned in step 3 is one or more of lithium ingots, lithium strips, lithium sheets, lithium powder, and lithium alloys.
[0031] Furthermore, the amount of lithium source used in step 3 is 2~50mg.
[0032] Furthermore, the heating temperature of the lithium source in step 3 is 200-400℃.
[0033] Furthermore, the heat-resistant tool mentioned in step 3 is any one of stainless steel scrapers, ceramic scrapers, ceramic tweezers, and ceramic long-handled tools.
[0034] Furthermore, in step 4, the amount of MXene base film used is 8~10mg.
[0035] Furthermore, in step 4, the amount of MXene-modified copper current collector used is 8~10 mg.
[0036] Furthermore, the present invention can achieve mass production of ultrathin MXene-based film-lithium metal composite foil through roll-to-roll continuous equipment.
[0037] Furthermore, the present invention also provides an ultrathin MXene-lithium metal composite foil obtained by the above preparation method, with a thickness between 2 and 50 micrometers, which can be used as a negative electrode material for lithium metal batteries.
[0038] Specifically, the ultrathin MXene-based film-lithium metal composite foil has a highly (110) crystal plane preferred orientation, a large grain size of 100 μm to 1 cm, internal compressive stress, and lithium ions have a rapid migration ability on its surface, which can induce the formation of a LiF-rich solid electrolyte interphase (SEI) phase, and has excellent deposition / stripping cycle stability.
[0039] Furthermore, the ultrathin MXene-lithium metal composite foil, as an electrode material (negative electrode material or positive electrode material) for lithium metal batteries, can achieve a specific negative / positive capacity ratio (N / P ratio) by controlling its thickness, and can realize the preparation of lithium metal batteries with an energy density of over 400 Wh / kg.
[0040] Furthermore, by precisely controlling the thickness and capacity, and using it as a current collector for the negative electrode of a conventional lithium-ion battery, precise pre-lithiation of the ultrathin MXene base film-lithium metal composite foil (used as a negative electrode material) can be achieved.
[0041] Furthermore, based on a general inventive concept, the present invention also provides the application of the ultrathin MXene-lithium metal composite foil as a negative electrode material in the preparation of lithium metal batteries.
[0042] Furthermore, based on a general inventive concept, the present invention also provides a lithium metal battery that uses the ultrathin MXene base film-lithium metal composite foil as the negative electrode.
[0043] Furthermore, based on a general inventive concept, the present invention also provides a pre-lithiated anode, wherein the lithium metal anode is pre-lithiated using the ultrathin MXene-based film-lithium metal composite foil, wherein the lithium metal anode is any one of graphite, silicon carbide, and silicon suboxide.
[0044] Compared with the prior art, the advantages of the present invention are: The preparation method of this invention, through the control of MXene, can produce lithium metal foil with a thickness of 2-50 micrometers and a preferred orientation of the (110) crystal plane, and is suitable for roll-to-roll continuous production. The ultrathin MXene-based film-lithium metal composite foil of this invention can be used as a negative electrode for lithium metal batteries, and can also be used for precise pre-lithiation treatment of traditional lithium-ion battery negative electrode materials (such as graphite, silicon carbide, silicon suboxide, etc.). Attached Figure Description
[0045] Figure 1 This is an optical photograph of Example 1; Figure 2 Here is a cross-sectional SEM image of Example 1; Figure 3 This is a planar SEM image of Example 1; Figure 4 The XRD pattern of Example 1; Figure 5 This is an optical photograph of Example 3; Figure 6 Here is a cross-sectional SEM image of Example 3; Figure 7 The XRD pattern of Example 3; Figure 8 This is a SEM image of the surface after cryo-focused ion beam treatment in Example 3; Figure 9 The surface reverse polar pattern of Example 3; Figure 10 This is a planar average orientation difference distribution diagram for Example 3; Figure 11 This is a cross-sectional SEM image of Example 3 after cryo-focused ion beam treatment; Figure 12 The cross-sectional inverse pole figure of Example 3; Figure 13 This is a cross-sectional average orientation difference distribution diagram for Example 3; Figure 14 This is an optical photograph of Example 4; Figure 15 This is a schematic diagram of roll-to-roll continuous production. Figure 16 The average coulomb efficiency diagrams for Example 1 and Comparative Example 1 are shown. Figure 17 For Example 1 and Comparative Example 1, at a current density of 1 mA / cm 2 Surface capacity 2 mAh / cm 2 The deposition / stripping cycle curve is shown below; Figure 18 The deposition / stripping rate performance curves for Example 1 and Comparative Example 1 are shown. Figure 19 The average coulomb efficiency diagrams for Example 3 and Comparative Example 2 are shown. Figure 20 For Example 3 and Comparative Example 2, at a current density of 1 mA / cm² 2 Surface capacity 2 mAh / cm 2 The deposition / stripping cycle curve is shown below; Figure 21 The deposition / stripping rate performance curves for Example 3 and Comparative Example 2 are shown. Figure 22 The rate performance diagrams are for the LFP cells assembled in Example 1 and Comparative Example 1. Figure 23 The circuit performance diagrams show the LFP cells assembled in Example 1 and Comparative Example 1. Figure 24 The rate performance graphs show the NCM83 batteries assembled in Example 3 and Comparative Example 2. Figure 25 The cycling performance graphs are for the NCM83 batteries assembled in Example 3 and Comparative Example 2. Figure 26 This is an optical image of the soft-pack battery assembled with NCM92 in Example 4; Figure 27 The charge / discharge curves of the pouch battery assembled with NCM92 were obtained for Example 4; Figure 28 The circuit performance diagram of the pouch cell assembled with NCM92 in Example 4 is shown. Figure 29 This is a delithiation curve for Example 5; Figure 30 The first charge-discharge curves and first coulombic efficiency of the silicon suboxide anode before and after pre-lithiation are shown in Example 5. Detailed Implementation
[0046] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0047] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods; unless otherwise specified, the reagents, raw materials, etc. used in the following examples are all commercially available products.
[0048] The micron-sized silicon suboxide (SiO2) used in the following examples and comparative examples x All are in powder form and produced by Shanghai Xiangtian Nanomaterials Co., Ltd., including micron-sized SiO₂. x The product number XT-SIO-5U has a median particle size D50 of 5μm and a silicon-oxygen atomic ratio of 6:4.
[0049] The argon gas used in the following examples and comparative examples had a purity of 99.99%.
[0050] In the following examples or comparative examples, room temperature or normal temperature refers to 25±5℃. Example 1
[0051] Example 1 provides a continuous preparation method for an ultrathin MXene-lithium metal composite foil with (110) crystal plane orientation, the specific steps of which are as follows: Step 1: Use the MILD method (see the reference "minimally intensive layer delamination" for details); Nature (2014, 516, 78-81.) Synthesized MXene dispersion, specifically as follows: Place 12 mL of 9.0 M HCl aqueous solution, 2 mL of 49 wt.% HF aqueous solution and 2 g of LiF into a polytetrafluoroethylene reactor, and then slowly add 1 g of MAX (Ti3AlC2, powder, 200 mesh, Jilin Yiyi Technology Co., Ltd.). The polytetrafluoroethylene reactor was placed in a 40°C oil bath and stirred magnetically for 24 hours. After the reaction, the product was washed with deionized water and centrifuged at 3500 rpm for 5 minutes to remove the supernatant. The above steps were repeated until the pH of the supernatant reached approximately 7. Then, 1.5 g LiCl was added to 10 mL of the washed mixture, and the mixture was stirred at room temperature for 4 h. The product was then washed with deionized water and centrifuged at 3500 rpm for 5 min to obtain a dispersion. The dispersion was then sonicated at -5℃ for 1 h (ultrasonic power of 200 W) and centrifuged at 2000 rpm for 30 min. The supernatant was retained as the MXene dispersion.
[0052] Step 2: Vacuum filtration to prepare MXene-based membrane, specifically: 1.5 mL of 6.4 mg / mL MXene dispersion was filtered through a water pump onto an aqueous filter membrane (mixed cellulose filter membrane, Shanghai Xinya Purification Device Factory, pore size 0.22 μm) with a diameter of 4 cm. The membrane was then vacuum dried at 30 °C for 12 h to obtain an MXene base membrane with a thickness of 8 μm.
[0053] Step 3: Surface treatment, specifically: In an argon-protected glove box, a stainless steel sheet containing 12 mg of lithium metal was placed on a 350°C heating table and heated until the lithium metal melted into a liquid state. The liquid lithium metal was then continuously scraped with a stainless steel cell rod until a fresh and shiny surface was exposed.
[0054] Step 4: Hot stamping of lithium metal, specifically: The MXene base film (4 cm in diameter, 8 μm in thickness, and 9.6 mg in weight, in disc shape) prepared in step 2 is placed on the surface of the molten liquid lithium in step 3 (350°C). This allows the liquid lithium metal to adhere to the surface of the MXene base film. After cooling to room temperature, an ultrathin MXene base film-lithium metal composite foil with a thickness of 15 μm is obtained and used as a negative electrode material for lithium batteries.
[0055] An optical image of the ultrathin MXene-based film-lithium metal composite foil prepared in Example 1 is shown below. Figure 1 As shown, it exhibits a uniform, flat, and glossy surface. The SEM cross-sectional image is as follows. Figure 2 As shown, a distinct bilayer structure is revealed, with an 8 μm MXene substrate film at the bottom and a 15 μm lithium metal film at the top. A clear and tight interface exists between the two, indicating good surface contact. The SEM image of its surface is shown below. Figure 3 As shown, a smooth lithium metal surface is revealed. Its XRD pattern is as follows. Figure 4As shown, it exhibits good BBC structure diffraction peaks of metallic lithium and has obvious (110) crystal plane preferred orientation with an orientation coefficient of 2.4. Example 2
[0056] Example 2 provides a continuous preparation method for an ultrathin MXene-lithium metal composite foil with (110) crystal plane orientation. The preparation method of Example 2 differs from that of Example 1 in that: In step 3, the heating temperature on the heating platform is 300°C, and the other steps and conditions are the same as in Example 1. Example 3
[0057] Example 3 provides a continuous preparation method for an ultrathin MXene-lithium metal composite foil with (110) crystal plane orientation. The preparation method of Example 3 differs from that of Example 1 in that: In step 3, the amount of lithium metal sheet used is 20 mg, and the other steps and conditions are the same as in Example 1; finally, an ultrathin MXene base film-lithium metal composite foil with a thickness of 25 μm is obtained.
[0058] An optical image of the ultrathin MXene-based film-lithium metal composite foil prepared in Example 3 is shown below. Figure 5 As shown, it exhibits a uniform, flat, and glossy surface. The SEM cross-sectional image is as follows. Figure 6 As shown, a distinct bilayer structure is observed, with an 8 μm MXene substrate film at the bottom and a 25 μm lithium metal film at the top. A clear and tight interface exists between the two, indicating good surface contact. Its XRD pattern is shown below. Figure 7 As shown, it exhibits good BBC structure diffraction peaks of metallic lithium and has obvious (110) crystal plane preferred orientation with an orientation coefficient of 2.69.
[0059] Treatment was performed using cryo-focused ion beam (FIB) with a Thermofisher Helios 5CX (with a cooling stage), and referenced in the literature. Nature Materials, The surface and cross-section of the planar sample (i.e., the ultrathin MXene-lithium metal composite foil described in Example 3) after processing (using the method in 2024, 23, 1678–1685) were analyzed by electron backscatter diffraction (EBSD). The SEM images, inverse pole figure (IPF) images, and mean orientation difference distribution (KAM) maps of the processed planar sample are shown below. Figure 8 , 9 As shown in Figure 10, large (110) oriented grains exceeding 300 μm are displayed. The surface sample has a highly (110) crystal plane preferred orientation, consistent with the XRD results, and is accompanied by a uniform orientation difference. The surface lithium metal has uniform stress inside.
[0060] The SEM images, inverse pole figure (IPF) images, and mean orientation difference distribution (KAM) of the cross-sectional sample after FIB processing are shown below. Figure 11 , 12 As shown in Figures 1 and 13, the (110) crystal plane shows a distinct preferred orientation and internal stress distribution. Example 4
[0061] Example 4 provides a method for preparing a large-area ultrathin MXene-based film-lithium metal composite foil. The difference between the preparation method of Example 4 and Example 1 is that: In step 2, instead of preparing the MXene dispersion by vacuum filtration, 10 mg / mL MXene dispersion (0.2 mL) was coated onto a commercial copper foil current collector (15×20 mm, 9 μm thick, single-sided polished, KELUDE) using a 10 μm scraper and dried under vacuum at 60 °C for 12 h to obtain the MXene-modified copper foil current collector.
[0062] In step 3, lithium metal particles (50 mg) are used.
[0063] In step 4, MXene-modified copper foil current collectors are used to replace the MXene base film for hot-pressing molten lithium.
[0064] In addition, after cooling in step 4, the large-area ultrathin MXene base film-lithium metal composite foil was prepared and cut into a suitable soft-pack battery using a die-cutting machine. The negative electrode size was 48×56mm. Other steps and conditions were the same as in Example 1.
[0065] Optical specimen of the obtained large-area ultrathin MXene-lithium metal composite foil as an electrode for pouch cells is shown below. Figure 14 As shown, Figure 14 The results show that it has a large area of uniform, flat, and bright metallic lithium surface. Example 5
[0066] Example 5 provides a continuous preparation method for an ultrathin MXene-lithium metal composite foil with (110) crystal plane orientation. The preparation method of Example 5 differs from that of Example 1 in that: In step 2, during filtration, the concentration of the MXene dispersion was 2.6 mg / mL and the volume was 0.5 mL, resulting in an MXene-based film with a thickness of 1 μm.
[0067] In step 3, the amount of lithium metal sheet used is 4 mg, and the other steps and conditions are the same as in Example 1, to obtain an ultrathin MXene base film-lithium metal composite foil with a thickness of 5 μm, which is used as a negative electrode material for lithium batteries.
[0068] The delithiation curve of the ultrathin MXene-based film-lithium metal composite foil prepared in Example 5 is as follows: Figure 29 As shown, the areal capacity of lithium metal is 1.06 mAh cm⁻¹. -2 .
[0069] The ultrathin MXene-based film-lithium metal composite foil prepared in Example 5 was used to treat silicon suboxide (produced by Shanghai Xiangtian Nanomaterials Co., Ltd., in which micron-sized SiO₂) x The product number XT-SIO-5U has a median particle size D50 of 5 μm and a silicon-oxygen atomic ratio of 6:4. Pre-lithiation of the negative electrode was performed by directly stacking the silicon suboxide negative electrode from Example 5 onto the substrate and conducting constant current charge-discharge tests (using a lithium metal sheet as the counter electrode and the silicon suboxide negative electrode from Example 5 as the working electrode to assemble a half-cell; constant current discharge at 100 mA / g to 0.01 V, followed by constant current charging at the same current density to 2.0 V). The initial charge-discharge curve is shown below. Figure 30 As shown.
[0070] from Figure 30 As can be seen, the open-circuit voltage of the un-pre-lithiated silicon suboxide anode half-cell is 1.82 V, and the initial discharge capacity is 2286 mAh g. -1 The initial charge capacity is 1782 mAh g. -1 The initial Coulomb efficiency was 78.03%.
[0071] The open-circuit voltage of the pre-lithiated silicon anode half-cell using Example 5 was 0.53 V, and the initial discharge capacity was 2126 mAh g. -1 The initial charge capacity is 2134 mAh g. -1 The initial coulombic efficiency was 100.04%. By controlling the lithium metal loading, precise pre-lithiation of silicon suboxide anodes or other traditional anodes (such as graphite and silicon carbide) can be achieved.
[0072] Comparative Example 1 Comparative Example 1 describes a half-cell assembled using an electrochemical deposition method (with a 12 mm diameter copper foil as the working electrode and a lithium metal sheet as the counter electrode), at a speed of 0.1 mA / cm². 2 At a current density of 30 h, the deposition capacity was 3 mAh / cm³. 2 A 15 μm thick layer of metallic lithium was deposited as the negative electrode on a copper foil current collector (9 μm thick, single-sided polished, KELU). (For specific methods, refer to the literature.) Nano-Micro Lett. 2025, 17, 111.).
[0073] Comparative Example 2 Comparative Example 2 shows the deposition of 25 μm thick lithium metal as a negative electrode on a copper foil current collector (9 μm thick, single-sided polished, KELU) by electrochemical deposition (same as Comparative Example 1).
[0074] Comparative Example 3 The method of Comparative Example 3 differs from that of Example 4 in that the commercial copper foil current collector is not modified in step 2, while in step 4, molten lithium is hot-pressed onto the unmodified copper current collector as an ultrathin lithium anode.
[0075] Performance testing Two identical ultrathin MXene-based film-lithium metal composite foils prepared using the above method (Examples 1, 2, 3, 4, 5) were used as lithium battery anode materials, or as the lithium metal anodes in Comparative Examples 1 and 2, to assemble lithium-||lithium symmetric batteries (using two identical lithium metal materials as the working electrode and counter electrode, respectively, with 20 μL of 1 M LiTFSI inDOL:DME=1:1 vol% with 1% LiNO3 (Suzhou Duoduo Chemical Technology Co., Ltd., LS-002) as the electrolyte, and Celgard 2500 as the separator; the specific preparation method of the battery is described in the reference). Nano-Micro Lett. 2025, 17, 111.), constant current deposition / stripping tests were performed at different current densities; Specifically, the ultrathin lithium metal foils prepared in Examples 1, 2, 3, 4, and 5, or the lithium metal in Comparative Examples 1 and 2, were used as negative electrodes and assembled with nickel-cobalt-manganese ternary positive electrodes (NCM83 or NCM92) and lithium iron phosphate positive electrodes (LFP) to form lithium metal full cells (with a negative / positive electrode capacity ratio (N / P ratio) of 1.2~2.5). Specifically, these were CR2032 coin cells or pouch cells. NCM83 and LFP were assembled into CR2032 coin cells, and NCM92 into pouch cells. Constant current charge-discharge tests were performed to characterize their cycle and rate performance (LFP||Li coin cells underwent rate performance testing at 0.1, 0.2, 0.5, 1, 2, and 3C rates, and 1000 cycles were performed at 0.5C, with a voltage range of 2.5-3.8). V; NCM83||Li button cell battery rate performance was tested at 0.1, 0.2, 0.5, 1, 2, and 5C rates, and 160 cycles were performed at 0.5C, with a voltage range of 2.8-4.3 V; NCM||92 pouch cell battery cycle test was performed at 0.1C, with a voltage range of 2.8-4.3 V).
[0076] References for NCM83 and NCM92 (Energy Environ. Sci. 2024, 17,The LFP positive electrode was obtained by the method described in 4283-4294., and was purchased from KELU, model MA-EN-CA-0015.
[0077] The test results are as follows: Figure 15 This is a schematic diagram of roll-to-roll continuous production in Example 4.
[0078] Figure 16 The figure shows a comparison of the average coulombic efficiency between Example 1 and Comparative Example 1. As can be seen from the figure, during 50 deposition / stripping cycles, the average coulombic efficiency of Example 1 reached 99.7%, which was significantly higher than that of Comparative Example 1 (98.2%).
[0079] Figure 17 Example 1 and Comparative Example 1 were compared at a current density of 1 mA / cm². 2 Surface capacity 2 mAh / cm 2 The deposition / stripping cycle voltage profiles were obtained under a depth of discharge (DOD) of 68.2%. Example 1 exhibited stable deposition / stripping for 450 h, demonstrating excellent deep discharge cycle stability.
[0080] Figure 18 The deposition / stripping rate performance curves for Example 1 and Comparative Example 1 are shown. Example 1 was performed at 0.5-4 mA / cm². 2 All exhibited stable voltage curves and lower overpotentials, indicating that Example 1 has faster interfacial ion transport and lower interfacial impedance, thus demonstrating excellent deposition / stripping kinetics.
[0081] Figure 19 The figure shows a comparison of the average coulombic efficiency between Example 3 and Comparative Example 2. As can be seen from the figure, during 50 deposition / stripping cycles, the average coulombic efficiency of Example 3 reached 99.8%, significantly higher than that of Comparative Example 2 (98.1%).
[0082] Figure 20 Example 3 and Comparative Example 2 were compared at a current density of 1 mA / cm². 2 Surface capacity 2 mAh / cm 2 The deposition / stripping cycle voltage profiles were obtained under a depth of discharge (DOD) of 44.2%. Example 3 exhibited stable deposition / stripping for over 800 h, demonstrating excellent deep discharge cycle stability.
[0083] Figure 21 The deposition / stripping rate performance curves for Example 3 and Comparative Example 2 are shown. Example 3 was performed at 0.5-4 mA / cm². 2 All exhibited stable voltage curves and lower overpotentials, indicating that Example 3 has faster interfacial ion transport and lower interfacial impedance, thus demonstrating excellent deposition / stripping kinetics.
[0084] Figure 22 The graph shows the rate performance of the LFP cells assembled in Example 1 and Comparative Example 1. Example 1 exhibits a higher specific capacity at high rates, indicating superior reaction kinetics.
[0085] Figure 23 The diagram shows the cycle performance of the LFP cells assembled in Example 1 and Comparative Example 1. Example 1 was able to maintain stable cycling for 1000 cycles, while Comparative Example 1 failed after 100 cycles.
[0086] Figure 24 The graph shows the rate performance of the NCM83 batteries assembled in Example 3 and Comparative Example 2. Example 3 exhibits a higher specific capacity at high rates, indicating superior reaction kinetics.
[0087] Figure 25 The graph shows the cycle performance of the NCM83 batteries assembled in Example 3 and Comparative Example 2. Example 3 was able to maintain stable cycling for 160 cycles, while Comparative Example 2 failed after 40 cycles.
[0088] Figure 26 This is an optical image of the lithium metal pouch cell assembled with an NCM92 cathode according to Example 4.
[0089] Figure 27 The charge-discharge curves of the lithium metal pouch battery assembled with NCM92 cathode in Example 4 show a discharge capacity of 5Ah and an average voltage of 3.85 V, with an energy density of 430 Wh / kg.
[0090] Figure 28 The graph shows the cycle performance of the lithium metal pouch cell assembled with NCM92 cathode in Example 4. After 112 cycles at 0.5C, the capacity retention rate is as high as 84.5%, showing excellent practical potential.
[0091] Figure 29 The delithiation curve for Example 5 shows that the areal capacity of the loaded lithium metal is 1.06 mAh cm⁻¹. -2 .
[0092] Figure 30 The first charge-discharge curves of the silicon suboxide anode before and after pre-lithiation are shown in Example 5. After pre-lithiation, the first coulombic efficiency of the silicon suboxide anode increased from 78.03% to 100.04%.
[0093] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing an ultrathin MXene-based film-lithium metal composite foil with (110) crystal plane orientation, characterized in that, Includes the following steps: Step 1: Synthesize MXene dispersion; Step 2: Prepare an MXene-based membrane or an MXene-modified copper current collector and use it as a substrate. The MXene-based membrane is obtained by preparing the MXene dispersion in Step 1 onto an aqueous filter membrane through methods such as vacuum filtration, spraying, or scraping. Step 3: Under a protective atmosphere, heat the lithium source to a molten state to obtain liquid lithium metal; use a heat-resistant tool to scrape the surface of the liquid lithium metal until a fresh and bright surface is exposed; Step 4: Liquid lithium metal is adhered to the surface of MXene base film or MXene modified copper current collector as a coating by hot stamping. The thickness of the lithium metal coating is controlled by adjusting the lithium loading. Then, it is cooled to room temperature to obtain an ultrathin MXene base film-lithium metal composite foil with (110) crystal orientation, which can be used as a negative electrode material.
2. The preparation method according to claim 1, characterized in that, The MXene mentioned in step 1 is Ti3C2T containing end groups such as -F, -O, and -OH. x Or Nb2CT x Nb4C3T x V2CT x V4C3T x Mo2CT x .
3. The preparation method according to claim 1, characterized in that, The thickness of the MXene base film mentioned in step 2 is 1 μm to 10 μm.
4. The preparation method according to claim 1, characterized in that, The MXene-modified copper current collector mentioned in step 2 is obtained by coating the MXene dispersion onto the copper current collector by spraying or scraping. The thickness of the MXene coating in the MXene-modified copper current collector described in step 2 is 0.1 μm to 2 μm.
5. The preparation method according to claim 1, characterized in that, The lithium source mentioned in step 3 is one or more of lithium ingots, lithium strips, lithium sheets, lithium granules, lithium powder, and lithium alloys.
6. The preparation method according to claim 1, characterized in that, The heating temperature of the lithium source in step 3 is 200-400℃; the heat-resistant tool in step 3 is any one of stainless steel scraper, ceramic scraper, ceramic tweezers, and ceramic long-handled tool.
7. An ultrathin MXene-lithium metal composite foil prepared by the method according to any one of claims 1 to 6, characterized in that, With a thickness between 2 and 50 micrometers, it can be used as a negative electrode material for lithium metal batteries.
8. The application of the ultrathin MXene-based film-lithium metal composite foil as a lithium metal anode material in the preparation of lithium metal batteries according to claim 7.
9. A lithium metal battery, characterized in that, The ultrathin MXene-lithium metal composite foil of claim 7 is used as the negative electrode.
10. A pre-lithiated anode, characterized in that, The lithium metal anode is pre-lithiated using the ultrathin MXene-based film-lithium metal composite foil as described in claim 7, wherein the lithium metal anode is any one of graphite, silicon carbide, and silicon suboxide.