Lithium-based negative electrode material and preparation method and application thereof

Abstract

The application discloses a lithium-based negative electrode material and a preparation method and application thereof, and relates to the technical field of lithium metal negative electrodes. The preparation method of the lithium-based negative electrode material comprises the following steps: after grinding different fluoride evaporation sources, the fluoride evaporation sources are placed below a lithium foil substrate; the process parameters of an evaporation process are adjusted; the fluoride evaporation sources are subjected to pre-dissolution treatment; the evaporation source baffle and the substrate baffle are opened, the lithium foil substrate is kept rotating, fluorinated SEI is evaporated on the surface of the lithium foil substrate, and the lithium-based negative electrode material is obtained. The application overcomes the SEI defects, takes into account high mechanical strength and high ionic conductivity, significantly improves the cycle life and electrochemical performance of the lithium metal negative electrode, and provides strong support for the research and development of the next generation of high-energy-density batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium metal anode technology, specifically to a lithium-based anode material, its preparation method, and its application. Background Technology

[0002] With the rapid development of new energy technologies, the research and application of high-energy-density batteries are receiving increasing attention. Lithium metal anodes, due to their high theoretical specific capacity and low lithium intercalation potential, are considered ideal anode materials for next-generation high-energy-density batteries. However, lithium metal anodes face a series of challenges in practical applications, especially in terms of cycle stability.

[0003] During battery cycling, the lithium metal anode readily reacts with the electrolyte to form an unstable solid-state electrolyte interface (SEI). This interface layer has a crucial impact on battery performance. However, existing SEIs typically suffer from several defects, such as low mechanical strength, which easily leads to the growth of lithium dendrites, potentially causing internal short circuits and safety hazards; low ionic conductivity, limiting the efficient diffusion and uniform deposition of lithium ions, affecting the battery's charge-discharge performance and cycle life; and poor interfacial contact, resulting in electrolyte penetration and increased interfacial impedance, further exacerbating battery performance degradation.

[0004] To overcome these shortcomings, researchers have attempted to optimize the performance of lithium metal anodes by constructing artificial SEIs. Among them, fluoride materials, represented by lithium fluoride (LiF), have attracted much attention due to their high mechanical strength and excellent ionic conductivity. However, commonly used fluoride artificial SEIs often have performance limitations, making it difficult to simultaneously meet the requirements of high mechanical strength and high ionic conductivity.

[0005] Currently, methods for preparing artificial SEIs mainly include liquid-phase chemical methods, chemical vapor deposition (CVD), and atomic layer deposition (ALD). While liquid-phase chemical methods are simple and easy to implement, they face difficulties in controlling interface uniformity, thickness, and composition distribution, are prone to generating impurity byproducts, and have high requirements for the reaction environment, leading to decreased protective layer stability. Although CVD and ALD methods can produce high-quality films, the equipment is expensive, the processes are complex, and the efficiency is low. Furthermore, the preparation of fluorinated SEIs requires gaseous precursors, and the processes face limitations in reactant gas selectivity and safety, making them unsuitable for large-area and large-scale industrial preparation.

[0006] Therefore, it is particularly important to develop an artificial SEI preparation technology that can overcome the defects of existing SEIs, while also taking into account high mechanical strength and high ionic conductivity, and is suitable for industrial preparation. Summary of the Invention

[0007] The technical problem to be solved by this invention is that existing lithium metal anodes are difficult to overcome SEI defects and meet the requirements of high mechanical strength and high ionic conductivity. The purpose is to provide a lithium-based anode material, its preparation method and application, which overcomes SEI defects, takes into account both high mechanical strength and high ionic conductivity, significantly improves the cycle life and electrochemical performance of lithium metal anodes, and provides strong support for the research and development of next-generation high-energy-density batteries.

[0008] This invention is achieved through the following technical solution:

[0009] A method for preparing a lithium-based anode material includes the following steps:

[0010] Different fluoride evaporation sources were ground and placed under the lithium foil substrate;

[0011] Open the evaporation source baffle and adjust the process parameters for the vapor deposition process;

[0012] Pre-dissolve each fluoride evaporation source;

[0013] The substrate baffle is opened, and the lithium foil substrate is kept rotating. Fluorinated SEI is deposited on the surface of the lithium foil substrate to obtain lithium-based anode material.

[0014] As one possible design, the aforementioned fluorides include at least two of LiF, LaF3, and CeF3.

[0015] As one possible design, the aforementioned fluoride includes two raw materials: LiF and LaF3 or CeF3.

[0016] As one possible design, the vacuum level during the above-mentioned vapor deposition is less than 10. -5 Pa, the evaporation temperature of the fluoride evaporation source is 500-1450℃, and the evaporation rate is... The temperature of the lithium metal substrate is maintained at 25-50℃.

[0017] As one possible design, the pre-dissolution treatment of each fluoride evaporation source specifically includes the following steps:

[0018] Open the baffles of each fluoride evaporation source while keeping the base baffle closed. Simultaneously start heating each fluoride evaporation source, maintaining an evaporation flow rate of 0. Gradually adjust the crucible heating power to perform a pre-dissolution for a time of t1. At this point, the pre-dissolution temperature of each fluoride evaporation source reaches T. 1x Keep heating at t2;

[0019] Each fluoride evaporation source undergoes a second pre-dissolution process for a time of t3, at which point the pre-dissolution temperature of each fluoride evaporation source reaches T. 2x , keep heating t4, where X is each fluoride.

[0020] As one possible design, after the above-mentioned LiF pre-dissolution, the pre-dissolution temperature T 1LiF The temperature is 550-650℃; after CeF3 is pre-dissolved once, the pre-dissolution temperature T is... 1CeF3 The temperature is 1100-1150℃; after one pre-dissolution of LaF3, the pre-dissolution temperature T is... 1LaF3 The temperature is 1150-1250℃;

[0021] After the above-mentioned secondary pre-dissolution of LiF, the pre-dissolution temperature T 2LiF The temperature is 850-950℃; after secondary pre-dissolution of CeF3, the pre-dissolution temperature T 2CeF3 The temperature is 1200-1300℃; after secondary pre-dissolution of LaF3, the pre-dissolution temperature T is... 2LaF3 The temperature is 1300-1400℃.

[0022] As one possible design, the rotational speed of the aforementioned lithium foil substrate is maintained at 4-6 r / min.

[0023] As one possible design, the fluorinated SEI has a thickness of 200-300 nm and a lotus seedpod structure.

[0024] Secondly, the present invention provides a lithium-based anode material, which is prepared by the above-described preparation method.

[0025] Thirdly, the present invention provides the application of a lithium-based anode material prepared by the above-described preparation method in battery materials.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] Based on the uniformity advantage of vapor deposition, this invention extends vacuum thermal evaporation technology to the preparation of multi-source fluoride solid electrolyte interfaces for lithium metal anodes. By synergistically combining the structure and properties of the multi-source fluoride interface, multi-component synergistic composite of fluoride materials is achieved, thereby realizing the synergistic optimization of mechanical and ion dynamic properties. This constructs a lotus-pod structure fluoride hybrid solid electrolyte interface with both high mechanical strength and high ionic conductivity, significantly improving the cycle stability and electrochemical performance of lithium metal anodes. It solves problems such as uncontrolled lithium dendrite growth due to insufficient SEI mechanical properties, uneven deposition caused by limited lithium ion diffusion, interfacial side reactions caused by electrolyte corrosion, and interfacial layer failure caused by volume expansion.

[0028] The lithium-based anode material of this invention retains more than 75% of its capacity after 1000 cycles at 1C rate in lithium iron phosphate coin cells, and at 1 mA cm⁻¹... -2No significant dendrite formation was observed during lithium deposition at the specified current for 20 minutes. Furthermore, this technology is highly efficient, capable of preparing a 300nm thick fluoride layer within 8 minutes, with no harmful byproducts, making it suitable for large-scale industrial production. The SEI, through its structural and multifunctional design, provides comprehensive protection for the lithium metal anode, significantly improving its cycle stability and safety, and offering a reliable new solution for realizing high-performance lithium metal batteries. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0030] Figure 1 This is a schematic diagram illustrating the design principle of the lithium-based anode material of the present invention;

[0031] Figure 2 The graph shows the long-cycle performance of the LiF-CeF3@Li|LFP, LiF-LaF3@Li|LFP and bare Li|LFP batteries of the present invention at 1C rate.

[0032] Figure 3 The LiF-LaF3@Li, LiF-CeF3@Li and bare Li anodes of this invention are at 1 mA cm⁻¹ -2 In-situ optical images after deposition at constant current density for different times. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0034] Existing lithium metal anode materials suffer from problems such as uncontrolled lithium dendrite growth due to insufficient SEI mechanical properties, uneven deposition caused by restricted lithium ion diffusion, interfacial side reactions caused by electrolyte corrosion, and interfacial layer failure caused by volume expansion. Furthermore, existing liquid phase or single-source deposition methods are difficult to achieve uniform composite at the nanoscale, and the SEI layer often suffers from uneven thickness or unstable composition distribution.

[0035] This invention employs multi-source vacuum thermal evaporation technology to precisely construct a dense and uniform fluoride hybrid SEI layer with a lotus seedpod structure on the lithium metal surface by independently controlling the evaporation rate and deposition power of various fluorides (LiF, CeF3, LaF3). This achieves synergistic optimization of mechanical properties, ion diffusion, and chemical stability, enabling the SEI layer to possess mechanical support properties, ion diffusion channels, and chemical passivation barriers.

[0036] A method for preparing a lithium-based anode material includes the following steps:

[0037] S1. After grinding different fluoride evaporation sources, place them under the lithium foil substrate so that the evaporation current can cover the surface of the lithium foil substrate.

[0038] In some embodiments of the present invention, the fluoride includes at least two of LiF, LaF3 and CeF3.

[0039] Evaporation of LiF can improve the high mechanical strength and dendrite suppression ability of the anode material; evaporation of LaF3 and CeF3 can improve the ionic conductivity and chemical stability of the anode material.

[0040] Preferably, the fluoride comprises two raw materials: one is LiF, and the other is LaF3 or CeF3.

[0041] Preferably, the fluorides include LiF and LaF3.

[0042] Preferably, the fluorides include LiF and CeF3.

[0043] Preferably, the above-mentioned fluoride is ground to the micron level.

[0044] Preferably, the above-mentioned fluoride is ground and then placed in a high-purity tungsten crucible for vapor deposition to ensure that the material is pure and free of impurities.

[0045] Preferably, the lithium foil substrate is fixed 30-50 cm above the fluoride evaporation source so that the evaporation current can uniformly cover the substrate surface.

[0046] S2. Adjust the process parameters of the vapor deposition process.

[0047] In some embodiments of the present invention, the vacuum degree is less than 10 during the above-described vapor deposition. -5 Pa, the evaporation temperature of the fluoride evaporation source is 500-2200℃, and the evaporation rate is... The temperature of the lithium metal substrate is maintained at 25-50℃.

[0048] Vacuum degree less than 10 -5 Pa can prevent interference from oxygen or moisture, ensuring the high purity of the fluoride layer.

[0049] Preferably, during LiF deposition, the evaporation temperature is 850-950℃, and the evaporation rate is... When depositing LaF3 or CeF3 by vapor deposition, the evaporation temperature is 1200-1300℃, and the evaporation rate is... More preferably, the evaporation temperature is 1300-1400℃ when depositing LaF3.

[0050] High-performance fluorinated SEIs can be prepared by vapor deposition parameters within this range.

[0051] S3. Open the evaporation source baffle to pre-dissolve each fluoride evaporation source.

[0052] In some embodiments of the present invention, the pre-dissolution treatment of each fluoride evaporation source specifically includes the following steps:

[0053] S31. Open the evaporation source baffle, keep the base baffle closed, and simultaneously start heating each fluoride evaporation source. Monitor in real time and maintain the evaporation flow rate at 0. Gradually adjust the crucible heating power to perform a pre-dissolution. The pre-dissolution time is t1. At this time, the pre-dissolution temperature of each fluoride evaporation source reaches T. 1x (X = LiF, CeF3, LaF3), keep heating for t2, and the temperature of the evaporation source reaches the critical temperature close to evaporation.

[0054] After the first pre-dissolution at t1-t2, the temperature of the evaporation source reaches the near-evaporation temperature; after the second pre-dissolution at t3-t4, the temperature of the evaporation source reaches the temperature of the target evaporation rate. The two pre-dissolutions allow for thorough mixing of the fluoride before it is deposited on the lithium metal anode, and a stable target evaporation rate can be achieved. After the substrate baffle is opened, uniform deposition is facilitated.

[0055] S32. Each fluoride evaporation source undergoes a second pre-dissolution process for a time of t3, at which point the pre-dissolution temperature of each fluoride evaporation source reaches T. 2x (X = LiF, CeF3, LaF3), maintain heating for t4, until the temperature of the evaporation source reaches the critical temperature for the target evaporation rate.

[0056] Preferably, the sum of t1, t2, t3 and t4 of the above pre-dissolving treatment is 10-16 minutes.

[0057] Pre-dissolution treatment ensures that all evaporation sources operate stably with minimal power fluctuations, guaranteeing controllable component ratios during the next stage of vapor deposition.

[0058] Preferably, t1 is 2-4 min, t2 is 2-4 min, t3 is 2-4 min, and t4 is 2-4 min.

[0059] In some embodiments of the present invention, after the above-mentioned LiF is pre-dissolved once, the pre-dissolution temperature T1LiF 550-650℃; After CeF3 is pre-dissolved once, the pre-dissolution temperature T 1CeF3 The temperature is 1050-1150℃; after one pre-dissolution of LaF3, the pre-dissolution temperature T is... 1LaF3 The temperature is 1150-1250℃;

[0060] After the above-mentioned secondary pre-dissolution of LiF, the pre-dissolution temperature T 2LiF The temperature is 850-950℃; after secondary pre-dissolution of CeF3, the pre-dissolution temperature T 2CeF3 The temperature is 1200-1300℃; after secondary pre-dissolution of LaF3, the pre-dissolution temperature T is... 2LaF3 The temperature is 1300-1400℃.

[0061] S4. Open the evaporation source baffle and the substrate baffle to keep the lithium foil substrate rotating. At the same time, by adjusting the evaporation temperature of each fluoride evaporation source, fluorinated SEI is deposited on the surface of the lithium foil substrate to obtain the lithium-based anode material.

[0062] By evaporating a lithium foil substrate by rotation, a mixed fluoride SEI is deposited on the surface of the lithium foil substrate, which can achieve a multi-functional synergy of mechanical support, ionic conductivity and chemical protection.

[0063] In some embodiments of the present invention, the rotational speed of the lithium foil substrate is maintained at 4-6 r / min.

[0064] In some embodiments of the present invention, the thickness of the fluorinated SEI is 200-300 nm, and the fluorinated SEI has a lotus seedpod structure.

[0065] LiF provides high mechanical strength, while CeF3 / LaF3 enhances ionic conductivity and chemical stability, forming a robust and dense lotus-shaped multifunctional SEI that effectively suppresses dendrite growth and optimizes ion transport pathways.

[0066] Preferably, step S5 is also included: after the evaporation is completed, the lithium foil is cooled and stored in an anhydrous and oxygen-free environment.

[0067] Slowly cooling the lithium metal sheet to room temperature and storing it in an anhydrous and oxygen-free environment can prevent the fluoride layer from oxidizing or hydrolyzing.

[0068] Example 1

[0069] A method for preparing a lithium-based anode material includes the following steps:

[0070] S1. Grind LiF and CeF3 into micron-sized powders and place them into high-purity tungsten crucibles respectively. Fix the lithium foil substrate 40cm above the crucible.

[0071] S2. Use a high vacuum pump to adjust the vacuum level of the vapor deposition chamber to 10. -5Below Pa, the LiF crucible evaporation temperature was set to 950℃, and the evaporation rate was [missing information]. CeF3 crucible setup: 1300℃, evaporation rate... Maintain the temperature of the lithium metal substrate between 25-50℃;

[0072] S3. Open the evaporation source baffle while keeping the base baffle closed, and simultaneously start the heating of the LiF and CeF3 evaporation sources; perform a first pre-dissolution for 2 minutes, during which the LiF and CeF3 evaporation sources reach the pre-dissolution temperatures of 550℃ and 1100℃ respectively, and maintain heating for 2 minutes, monitoring in real time and keeping the evaporation flow rate at 0; after a second pre-dissolution for 2 minutes, the LiF and CeF3 evaporation sources reach the pre-dissolution temperatures of 950℃ and 1300℃ respectively, and maintain heating for 2 minutes, resulting in a fluoride layer thickness of 300 nm;

[0073] S4. Set the stage to rotate at a rate of 5 r / min, and simultaneously adjust the evaporation power of LiF and CeF3 to maintain a stable evaporation rate. and By opening the substrate baffle, 200nm lotus seedpod-structured LiF-CeF3 artificial SEIs with different compositions were deposited on the substrate surface to obtain lithium-based anode materials;

[0074] S5. After the vapor deposition is completed, the lithium metal sheet is slowly cooled to room temperature and stored in an anhydrous and oxygen-free environment.

[0075] Example 2

[0076] A method for preparing a lithium-based anode material includes the following steps:

[0077] S1. Grind LiF and CeF3 into micron-sized powders and place them into high-purity tungsten crucibles respectively. Fix the lithium foil substrate 30cm above the crucible.

[0078] S2. Use a high vacuum pump to adjust the vacuum level of the vapor deposition chamber to 10. -5 Below Pa, the LiF crucible evaporation temperature was set to 900℃, and the evaporation rate was [missing information]. CeF3 crucible settings: 1250℃, evaporation rate... Maintain the temperature of the lithium metal substrate between 25-50℃;

[0079] S3. While keeping the base baffle closed, simultaneously start the heating LiF and CeF3 evaporation sources; perform a first pre-dissolution for 4 minutes, during which the LiF and CeF3 evaporation sources reach the pre-dissolution temperatures of 600℃ and 1100℃ respectively, and maintain heating for 4 minutes, while monitoring in real time and keeping the evaporation flow rate at 0; then perform a second pre-dissolution for 4 minutes, during which the LiF and CeF3 evaporation sources reach the pre-dissolution temperatures of 900℃ and 1250℃ respectively, and maintain heating for 4 minutes;

[0080] S4. Set the stage to rotate at a speed of 5 r / min, and simultaneously adjust the evaporation power of LiF and CeF3 to maintain the evaporation rate at a constant speed. and By opening the substrate baffle, 300nm lotus seedpod-structured LiF-CeF3 artificial SEIs with different compositions were deposited on the substrate surface to obtain lithium-based anode materials.

[0081] S5. After the vapor deposition is completed, the lithium metal sheet is slowly cooled to room temperature and stored in an anhydrous and oxygen-free environment.

[0082] Example 3

[0083] A method for preparing a lithium-based anode material includes the following steps:

[0084] S1. Grind LiF and CeF3 into micron-sized powders and place them into high-purity tungsten crucibles respectively. Fix the lithium foil substrate 50cm above the crucible.

[0085] S2. Use a high vacuum pump to adjust the vacuum level of the vapor deposition chamber to 10. -5 Below Pa, the LiF crucible evaporation temperature was set to 850℃, and the evaporation rate was [missing information]. CeF3 crucible setup: 1200℃, evaporation rate... Maintain the temperature of the lithium metal substrate between 25-50℃;

[0086] S3. Open the evaporation source baffle while keeping the base baffle closed, and simultaneously start the heating of the LiF and CeF3 evaporation sources; perform a first pre-dissolution for 3 minutes, during which the LiF and CeF3 evaporation sources reach the pre-dissolution temperatures of 550℃ and 1100℃ respectively, and maintain heating for 3 minutes, monitoring in real time and keeping the evaporation flow rate at 0; then perform a second pre-dissolution for 3 minutes, during which the LiF and CeF3 evaporation sources reach the pre-dissolution temperatures of 850℃ and 1200℃ respectively, and maintain heating for 3 minutes;

[0087] S4. Set the stage to rotate at a rate of 5 r / min, and simultaneously adjust the evaporation power of LiF and CeF3 to maintain a stable evaporation rate. and By opening the substrate baffle, 250nm lotus seedpod-structured LiF-CeF3 artificial SEIs with different compositions were deposited on the substrate surface to obtain lithium-based anode materials;

[0088] S5. After the vapor deposition is completed, the lithium metal sheet is slowly cooled to room temperature and stored in an anhydrous and oxygen-free environment.

[0089] Example 4

[0090] A method for preparing a lithium-based anode material includes the following steps:

[0091] S1. Grind LiF and LaF3 into micron-sized powders and place them into high-purity tungsten crucibles respectively. Fix the lithium foil substrate 40cm above the crucible.

[0092] S2. Use a high vacuum pump to adjust the vacuum level of the vapor deposition chamber to 10. -5 Below Pa. The LiF crucible evaporation temperature was set to 850℃, and the evaporation rate was [missing information]. Set the LaF3 crucible to 1200℃ and the evaporation rate to [missing information]. Maintain the temperature of the lithium metal substrate between 25-50℃;

[0093] S3. Open the evaporation source baffle while keeping the base baffle closed, and simultaneously start heating the LiF and LaF3 evaporation sources; perform a first pre-dissolution for 4 minutes, during which the LiF and LaF3 evaporation sources reach pre-dissolution temperatures of 200℃ and 1300℃ respectively, and maintain these temperatures for 4 minutes, while monitoring in real time and keeping the evaporation flow rate at 0; then perform a second pre-dissolution for 4 minutes, during which the LiF and LaF3 evaporation sources reach pre-dissolution temperatures of 850℃ and 1200℃ respectively, and maintain these temperatures for 4 minutes.

[0094] S4. Open the evaporation source baffle and the substrate baffle. Maintain the substrate stage at a rotation speed of 6 r / min. Simultaneously, adjust the evaporation power of LiF and CeF3 to stabilize the evaporation rate. and By opening the substrate baffle, 300nm lotus seedpod-structured LiF-LaF3 artificial SEIs with different compositions were deposited on the substrate surface to obtain lithium-based anode materials;

[0095] S5. After the vapor deposition is completed, the lithium metal sheet is slowly cooled to room temperature and stored in an anhydrous and oxygen-free environment.

[0096] Comparative Example 1

[0097] This comparative example is basically the same as Example 4, except that only LiF evaporation was used.

[0098] Comparative Example 2

[0099] This comparative example is basically the same as Example 4, except that only LaF3 vapor deposition is used.

[0100] Comparative Example 3

[0101] This comparative example is basically the same as Example 4, except that only NaF vapor deposition is used.

[0102] Experimental Example 1

[0103] The lithium-based anode material of Example 1 (named LiF-CeF3@Li) was assembled with a lithium iron phosphate cathode (named LFP) to form a coin cell (named LiF-CeF3@Li|LFP); the lithium-based anode material of Example 4 (named LiF-LaF3@Li) was assembled with a lithium iron phosphate cathode (named LFP) to form a coin cell (named LiF-LaF3@Li|LFP). Long-cycle performance data for both were measured at 1C and 2C rates, comparing the coin cells assembled with bare lithium foil substrates (named bare Li) and lithium iron phosphate cathodes (named bare Li|LFP). The results are shown in Table 1 and... Figure 2 As shown.

[0104] LiF-CeF3@Li, LiF-LaF3@Li|LFP and bare Li were subjected to 1 mA cm⁻¹ -2 After deposition at a constant current density for 10 min and 20 min, in-situ optical detection was performed, and the results are as follows. Figure 3 As shown.

[0105] Table 1. Long-cycle performance data of LiF-CeF3@Li|LFP and bare Li|LFP batteries at 1C and 2C rates.

[0106]

[0107]

[0108] As shown in Table 1, the capacity retention rate exceeds 75% after 800 cycles at a 2C rate. Compared to the capacity retention rate after 1000 cycles at a 1C rate, the battery assembled with the lithium-based anode material in Example 1 has a significantly higher capacity retention rate than the battery assembled with the bare lithium foil substrate. Furthermore, compared to the battery assembled with the lithium-based anode material in Example 1 at a high 2C rate, the cycle capacity is significantly higher than that of the battery assembled with the bare lithium foil substrate.

[0109] Reference Figure 2 The lithium-based anode material (named LiF-CeF3@Li) was assembled with a lithium iron phosphate cathode (named LFP) into a coin cell (named LiF-CeF3@Li|LFP). After 1000 cycles at 1C, the capacity exceeded 95 mA / cm². -2 A lithium-based anode material (named LiF-LaF3@Li) and a lithium iron phosphate cathode (named LFP) were assembled into a coin cell (named LiF-LaF3@Li|LFP) with a capacity exceeding 95 mA cm⁻¹. -2Both exhibited a capacity retention rate exceeding 75%. In contrast, a coin cell assembled with a bare lithium foil substrate (named bare Li) and a lithium iron phosphate cathode (named bare Li|LFP) showed a capacity retention of only 46.9 mA / cm² after 1000 cycles at 1C. -2 The capacity retention rate is only 38.4%.

[0110] Reference Figure 3 LiF-CeF3@Li at 1 mA cm -2 Lithium deposition at 1 mA cm⁻¹ showed no significant dendrite formation after 10 min; LiF-LaF₃@Li|LFP deposition at 1 mA cm⁻¹ -2 Lithium deposition under a current of 1 mA for 20 min showed no obvious dendrite formation; while lithium foil substrates at 1 mA cm⁻¹ showed no significant dendrite formation. -2 Under a given current, lithium deposition for 10 minutes resulted in significant dendrite formation. This indicates that deposition of LiF-LaF3 or LiF-CeF3 can suppress lithium dendrite growth in lithium anode materials and improve the mechanical properties of the SEI.

[0111] Experiment Example 2

[0112] The thickness, mechanical strength and chemical stability of the samples from Comparative Examples 1-3, Example 1 and Example 4 were tested, and the results are shown in Table 2.

[0113] Table 2

[0114]

[0115] As can be seen from Table 2, Example 4 has the best overall performance, which indicates that only when LiF, LaF3 and CeF3 are used in combination for vapor deposition can the optimal number of cycles be achieved.

[0116] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a lithium-based anode material, characterized in that, Includes the following steps: Different fluoride evaporation sources are ground and placed under a lithium foil substrate. The fluorides include two raw materials: one is LiF, and the other is LaF3 or CeF3. Adjust the process parameters of the vapor deposition process; Open the evaporation source baffle and pre-dissolve each fluoride evaporation source, specifically including the following steps: Open the baffles of each fluoride evaporation source, keep the base baffle closed, and simultaneously start heating each fluoride evaporation source, maintaining an evaporation flow rate of 0, to perform a pre-dissolution for a time of t1. At this time, the pre-dissolution temperature of each fluoride evaporation source reaches T. 1x Keep heating at t2; Each fluoride evaporation source undergoes a second pre-dissolution process for a time of t3, at which point the pre-dissolution temperature of each fluoride evaporation source reaches T. 2x , keep heating t4, where X is each fluoride; After the LiF is pre-dissolved once, the pre-dissolution temperature T 1LiF The temperature is 550-600℃; after CeF3 is pre-dissolved once, the pre-dissolution temperature T is... 1CeF3 The temperature is 1100-1150℃; after one pre-dissolution of LaF3, the pre-dissolution temperature T is... 1LaF3 The temperature is 1150-1250℃; After the LiF is pre-dissolved twice, the pre-dissolution temperature T 2LiF The temperature is 850-950℃; after secondary pre-dissolution of CeF3, the pre-dissolution temperature T 2CeF3 The temperature is 1200-1300℃; after secondary pre-dissolution of LaF3, the pre-dissolution temperature T is... 2LaF3 The temperature is 1300-1400℃; The substrate baffle is opened, and the lithium foil substrate is kept rotating. Fluorinated SEI is deposited on the surface of the lithium foil substrate. The fluorinated SEI has a thickness of 200-300 nm and has a lotus seedpod structure. LaF3 or CeF3 is filled in the LiF host structure in the form of particles to form the lotus seedpod structure, thus obtaining a lithium-based anode material.

2. The method for preparing a lithium-based anode material according to claim 1, characterized in that, During the vapor deposition process, the vacuum level is less than 10. -5 Pa, the fluoride evaporation source has an evaporation temperature of 500-1450℃ and an evaporation rate of 0.5-3 Å / s, while the lithium metal substrate temperature is maintained at 25-50℃.

3. The method for preparing a lithium-based anode material according to claim 1, characterized in that, The rotational speed of the lithium foil substrate is maintained at 4-6 r / min.

4. A lithium-based anode material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 3.

5. The application of a lithium-based anode material prepared by the preparation method according to any one of claims 1 to 3 in the preparation of battery materials.

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